Chemical compounds

NEIL SCHLAGER, JAYNE WEISBLATT, ANDDAVID E. NEWTON, EDITORS

Charles B. Montney, Project Editor

Chemical Compounds

Neil Schlager, Jayne Weisblatt, and David E. Newton, Editors

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Weisblatt, Jayne.Chemical compounds / Jayne Weisblatt ; Charles B. Montney, project editor.

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con entscontentsvolume 1 Reader ’s Guide . . . . . . . . . . . . . . . . . . . . xiii

Timeline of the Development of

Chemical Compounds . . . . . . . . . . . . . . .xxi

Words to Know . . . . . . . . . . . . . . . . . .xxxvii

1,3-Butadiene . . . . . . . . . . . . . . . . . . . . . . . . 1

2,20-Dichlorodiethyl Sulfide . . . . . . . . . . . . . . 5

2-(4-Isobutylphenyl)propionic Acid . . . . . . . . . . 9

2,4,6-Trinitrotoluene . . . . . . . . . . . . . . . . . . 15

Acetaminophen . . . . . . . . . . . . . . . . . . . . . 19

Acetic acid . . . . . . . . . . . . . . . . . . . . . . . . 23

Acetylene . . . . . . . . . . . . . . . . . . . . . . . . . 27

Acetylsalicylic acid . . . . . . . . . . . . . . . . . . 31

Alpha-Tocopherol . . . . . . . . . . . . . . . . . . . . 37

Aluminum Fluoride . . . . . . . . . . . . . . . . . . . 41

Aluminum Hydroxide . . . . . . . . . . . . . . . . . 45

Aluminum Oxide . . . . . . . . . . . . . . . . . . . . 49

Aluminum Potassium Sulfate . . . . . . . . . . . . 53

Ammonia . . . . . . . . . . . . . . . . . . . . . . . . . 57

Ammonium Chloride . . . . . . . . . . . . . . . . . . 63

Ammonium Hydroxide . . . . . . . . . . . . . . . . 69

Ammonium Nitrate . . . . . . . . . . . . . . . . . . . 73

CHEMICAL COMPOUNDS

v

Ammonium Sulfate . . . . . . . . . . . . . . . . . . . 77

Amoxicillin . . . . . . . . . . . . . . . . . . . . . . . . 81

Amyl Acetate. . . . . . . . . . . . . . . . . . . . . . . 85

Amyl Nitrite . . . . . . . . . . . . . . . . . . . . . . . 89

Ascorbic Acid . . . . . . . . . . . . . . . . . . . . . . 93

Benzene . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Benzoic Acid . . . . . . . . . . . . . . . . . . . . . . 105

Beta-Carotene . . . . . . . . . . . . . . . . . . . . . 109

Boric Acid. . . . . . . . . . . . . . . . . . . . . . . . . 115

Butane . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Butyl Acetate . . . . . . . . . . . . . . . . . . . . . . 125

Butyl Mercaptan . . . . . . . . . . . . . . . . . . . . 129

Butylated Hydroxyanisole and Butylated

Hydroxytoluene . . . . . . . . . . . . . . . . . . . . 133

Caffeine . . . . . . . . . . . . . . . . . . . . . . . . . . 137

Calcium Carbonate . . . . . . . . . . . . . . . . . . . 143

Calcium Hydroxide . . . . . . . . . . . . . . . . . . . 147

Calcium Oxide . . . . . . . . . . . . . . . . . . . . . . 151

Calcium Phosphate . . . . . . . . . . . . . . . . . . . 155

Calcium Silicate . . . . . . . . . . . . . . . . . . . . . 161

Calcium Sulfate . . . . . . . . . . . . . . . . . . . . .165

Camphor . . . . . . . . . . . . . . . . . . . . . . . . . . 171

Carbon Dioxide . . . . . . . . . . . . . . . . . . . . . 177

Carbon Monoxide . . . . . . . . . . . . . . . . . . . .183

Carbon Tetrachloride. . . . . . . . . . . . . . . . . .189

Cellulose . . . . . . . . . . . . . . . . . . . . . . . . . .195

Cellulose Nitrate . . . . . . . . . . . . . . . . . . . .201

Cellulose Xanthate . . . . . . . . . . . . . . . . . . 207

Chloroform . . . . . . . . . . . . . . . . . . . . . . . . 211

Chlorophyll . . . . . . . . . . . . . . . . . . . . . . . . 217

Cholesterol . . . . . . . . . . . . . . . . . . . . . . . 223

Cinnamaldehyde . . . . . . . . . . . . . . . . . . . . 229

Citric Acid . . . . . . . . . . . . . . . . . . . . . . . 233

Collagen . . . . . . . . . . . . . . . . . . . . . . . . . 239

Contents

vi CHEMICAL COMPOUNDS

Copper(I) Oxide . . . . . . . . . . . . . . . . . . . . 243

Copper(II) Oxide . . . . . . . . . . . . . . . . . . . . 247

Copper(II) Sulfate . . . . . . . . . . . . . . . . . . . . 251

Cumene . . . . . . . . . . . . . . . . . . . . . . . . . 255

Cyanoacrylate . . . . . . . . . . . . . . . . . . . . . 259

Cyanocobalamin . . . . . . . . . . . . . . . . . . . . 265

Denatonium Benzoate . . . . . . . . . . . . . . . . . 271

Dichlorodifluoromethane . . . . . . . . . . . . . . 277

Dichlorodiphenyltrichloroethane . . . . . . . . . 283

Dimethyl Ketone . . . . . . . . . . . . . . . . . . . 289

Ethyl Acetate . . . . . . . . . . . . . . . . . . . . . 293

Compounds by Formula . . . . . . . . . . . . . . . liii

Compounds by Element . . . . . . . . . . . . . . . lix

Compounds by Type . . . . . . . . . . . . . . . . . lxv

For Further Information . . . . . . . . . . . . . lxix

Index . . . . . . . . . . . . . . . . . . . . . . . . . lxxix

volume 2 Reader ’s Guide . . . . . . . . . . . . . . . . . . . . xiii




Ethyl Alcohol . . . . . . . . . . . . . . . . . . . . . 297

Ethylbenzene. . . . . . . . . . . . . . . . . . . . . . 303

Ethylene . . . . . . . . . . . . . . . . . . . . . . . . . 307

Ethylene Glycol . . . . . . . . . . . . . . . . . . . . . 313

Ethylene Oxide . . . . . . . . . . . . . . . . . . . . . 317

Folic Acid . . . . . . . . . . . . . . . . . . . . . . . . . 321

Formaldehyde . . . . . . . . . . . . . . . . . . . . . 325

Fructose . . . . . . . . . . . . . . . . . . . . . . . . . 329

Gamma-1,2,3,4,5,6-Hexachlorocyclohexane . . . 333

Gelatin . . . . . . . . . . . . . . . . . . . . . . . . . . 337

Glucose. . . . . . . . . . . . . . . . . . . . . . . . . . 343

CHEMICAL COMPOUNDS vii

Contents

Glycerol . . . . . . . . . . . . . . . . . . . . . . . . . 349

Hexane. . . . . . . . . . . . . . . . . . . . . . . . . . 353

Hydrogen Chloride . . . . . . . . . . . . . . . . . . 357

Hydrogen Peroxide . . . . . . . . . . . . . . . . . . 363

Iron(II) Oxide. . . . . . . . . . . . . . . . . . . . . . 367

Iron(III) Oxide . . . . . . . . . . . . . . . . . . . . . . 371

Isoamyl Acetate . . . . . . . . . . . . . . . . . . . . 377

Isoprene . . . . . . . . . . . . . . . . . . . . . . . . . .381

Isopropyl Alcohol . . . . . . . . . . . . . . . . . . . 387

Lactic Acid . . . . . . . . . . . . . . . . . . . . . . . .391

Lactose. . . . . . . . . . . . . . . . . . . . . . . . . . 397

L-Aspartyl-L-Phenylalanine Methyl Ester . . . . 401

Luminol . . . . . . . . . . . . . . . . . . . . . . . . . 407

Magnesium Chloride . . . . . . . . . . . . . . . . . . 411

Magnesium Hydroxide. . . . . . . . . . . . . . . . .415

Magnesium Oxide . . . . . . . . . . . . . . . . . . . .419

Magnesium Silicate Hydroxide . . . . . . . . . . 423

Magnesium Sulfate . . . . . . . . . . . . . . . . . . 429

Menthol . . . . . . . . . . . . . . . . . . . . . . . . . 435

Mercury(II) Sulfide . . . . . . . . . . . . . . . . . . 439

Methane . . . . . . . . . . . . . . . . . . . . . . . . . 443

Methyl Alcohol . . . . . . . . . . . . . . . . . . . . 449

Methyl Mercaptan . . . . . . . . . . . . . . . . . . 455

Methyl-t-butyl Ether . . . . . . . . . . . . . . . . . 459

Monosodium Glutamate . . . . . . . . . . . . . . . 465

N,N-Diethyl-3-Methylbenzamide . . . . . . . . . . 469

Naphthalene . . . . . . . . . . . . . . . . . . . . . . 473

Naproxen . . . . . . . . . . . . . . . . . . . . . . . . 477

Niacin . . . . . . . . . . . . . . . . . . . . . . . . . . 483

Nicotine . . . . . . . . . . . . . . . . . . . . . . . . . 487

Nitric Acid . . . . . . . . . . . . . . . . . . . . . . . 493

Nitric Oxide . . . . . . . . . . . . . . . . . . . . . . 497

Nitrogen Dioxide . . . . . . . . . . . . . . . . . . . 503

Nitroglycerin . . . . . . . . . . . . . . . . . . . . . . 507

viii CHEMICAL COMPOUNDS

Contents

Nitrous Oxide . . . . . . . . . . . . . . . . . . . . . . 513

Nylon 6 and Nylon 66 . . . . . . . . . . . . . . . . .519

Oxalic Acid . . . . . . . . . . . . . . . . . . . . . . . 525

Pectin . . . . . . . . . . . . . . . . . . . . . . . . . . . 531

Penicillin . . . . . . . . . . . . . . . . . . . . . . . . 535

Perchlorates . . . . . . . . . . . . . . . . . . . . . . .541

Petrolatum . . . . . . . . . . . . . . . . . . . . . . . 547

Petroleum . . . . . . . . . . . . . . . . . . . . . . . . 553

Phenol . . . . . . . . . . . . . . . . . . . . . . . . . . 559

Phosphoric Acid . . . . . . . . . . . . . . . . . . . . 565

Poly(Styrene-Butadiene-Styrene) . . . . . . . . . . 571

Polycarbonates. . . . . . . . . . . . . . . . . . . . . 575

Polyethylene . . . . . . . . . . . . . . . . . . . . . . 579

Polymethyl Methacrylate . . . . . . . . . . . . . . 583

Polypropylene . . . . . . . . . . . . . . . . . . . . . 587

Polysiloxane . . . . . . . . . . . . . . . . . . . . . . .591





Index . . . . . . . . . . . . . . . . . . . . . . . . . lxxix

volume 3 Reader ’s Guide . . . . . . . . . . . . . . . . . . . . xiii




Polystyrene . . . . . . . . . . . . . . . . . . . . . . . 597

Polytetrafluoroethylene . . . . . . . . . . . . . . . 603

Polyurethane . . . . . . . . . . . . . . . . . . . . . . 609

Polyvinyl Chloride . . . . . . . . . . . . . . . . . . .615

Potassium Bicarbonate . . . . . . . . . . . . . . . .621

Potassium Bisulfate . . . . . . . . . . . . . . . . . 625

CHEMICAL COMPOUNDS ix

Contents

Potassium Bitartrate . . . . . . . . . . . . . . . . . 629

Potassium Carbonate . . . . . . . . . . . . . . . . . 633

Potassium Chloride . . . . . . . . . . . . . . . . . . 639

Potassium Fluoride . . . . . . . . . . . . . . . . . . 643

Potassium Hydroxide . . . . . . . . . . . . . . . . 647

Potassium Iodide . . . . . . . . . . . . . . . . . . . .651

Potassium Nitrate. . . . . . . . . . . . . . . . . . . 655

Potassium Sulfate. . . . . . . . . . . . . . . . . . . 659

Propane . . . . . . . . . . . . . . . . . . . . . . . . . 663

Propylene . . . . . . . . . . . . . . . . . . . . . . . . 669

Pyridoxine . . . . . . . . . . . . . . . . . . . . . . . 673

Retinol . . . . . . . . . . . . . . . . . . . . . . . . . . 677

Riboflavin. . . . . . . . . . . . . . . . . . . . . . . . 683

Saccharin . . . . . . . . . . . . . . . . . . . . . . . . 689

Silicon Dioxide . . . . . . . . . . . . . . . . . . . . 695

Silver Iodide . . . . . . . . . . . . . . . . . . . . . . .701

Silver Nitrate . . . . . . . . . . . . . . . . . . . . . 705

Silver(I) Oxide . . . . . . . . . . . . . . . . . . . . . . 711

Silver(I) Sulfide . . . . . . . . . . . . . . . . . . . . . 715

Sodium Acetate . . . . . . . . . . . . . . . . . . . . .719

Sodium Bicarbonate . . . . . . . . . . . . . . . . . 723

Sodium Carbonate . . . . . . . . . . . . . . . . . . 729

Sodium Chloride. . . . . . . . . . . . . . . . . . . . 735

Sodium Cyclamate . . . . . . . . . . . . . . . . . . . 741

Sodium Fluoride . . . . . . . . . . . . . . . . . . . . 747

Sodium Hydroxide . . . . . . . . . . . . . . . . . . 753

Sodium Hypochlorite . . . . . . . . . . . . . . . . 759

Sodium Perborate . . . . . . . . . . . . . . . . . . . 765

Sodium Phosphate . . . . . . . . . . . . . . . . . . 769

Sodium Polyacrylate . . . . . . . . . . . . . . . . . 773

Sodium Silicate . . . . . . . . . . . . . . . . . . . . 779

Sodium Sulfite . . . . . . . . . . . . . . . . . . . . . 785

Sodium Tetraborate . . . . . . . . . . . . . . . . . 789

Sodium Thiosulfate . . . . . . . . . . . . . . . . . . 795

x CHEMICAL COMPOUNDS

Contents

Stannous Fluoride . . . . . . . . . . . . . . . . . . 799

Styrene . . . . . . . . . . . . . . . . . . . . . . . . . 803

Sucrose . . . . . . . . . . . . . . . . . . . . . . . . . 807

Sucrose Polyester . . . . . . . . . . . . . . . . . . . .813

Sulfur Dioxide . . . . . . . . . . . . . . . . . . . . . .819

Sulfuric Acid . . . . . . . . . . . . . . . . . . . . . . 825

Tannic Acid . . . . . . . . . . . . . . . . . . . . . . . .831

Testosterone . . . . . . . . . . . . . . . . . . . . . . 837

Theobromine . . . . . . . . . . . . . . . . . . . . . . 843

Thiamine . . . . . . . . . . . . . . . . . . . . . . . . 847

Toluene . . . . . . . . . . . . . . . . . . . . . . . . . 853

Triclocarban . . . . . . . . . . . . . . . . . . . . . . 859

Triclosan . . . . . . . . . . . . . . . . . . . . . . . . 863

Urea . . . . . . . . . . . . . . . . . . . . . . . . . . . 867

Vanillin . . . . . . . . . . . . . . . . . . . . . . . . . 873

Water. . . . . . . . . . . . . . . . . . . . . . . . . . . 879

Zinc Oxide . . . . . . . . . . . . . . . . . . . . . . . 885





Index . . . . . . . . . . . . . . . . . . . . . . . . . lxxix

CHEMICAL COMPOUNDS xi

Contents

reader’ guidereader’s guide

W ater; sugar; nylon; vitamin C. These substances are allvery different from each other. But they all share one

property in common: They are all chemical compounds. A che-mical compound consists of two or more chemical elements,joined to each other by a force known as a chemical bond.

This book describes 180 chemical compounds, somefamiliar to almost everyone, and some less commonly known.Each description includes some basic chemical and physicalinformation about the compound, such as its chemical for-mula, other names by which the compound is known, and themolecular weight, melting point, freezing point, and solubi-lity of the compound. Here are some things to know abouteach of these properties:

Other Names: Many chemical compounds have more thanone name. Compounds that have been known for many cen-turies often have common names that may still be used inindustry, the arts, or some other field. For example, muriaticacid is a very old name for the compound now called hydro-chloric acid. The name remains in common use today. Marineacid and spirit of salt are other ancient names for hydrochlo-ric acid, but they are seldom used in the modern world. Allcompounds have systematic names, names based on a set ofrules devised by the International Union of Pure and AppliedChemistry (IUPAC). For example, the systematic name for thepoisonous gas whose common name is mustard gas is 2,20-dichlorodiethyl sulfide. When chemists talk about chemical

CHEMICAL COMPOUNDS

xiii

compounds, they usually use only the official IUPAC namefor a compound since that name leaves no doubt as to thesubstance about which they are talking. In some cases, acompound may have more than one official name, dependingon the set of rules used in the naming process. For example,1,10-thiobis[2-chloroethane] is also an acceptable name formustard gas. The ‘‘Other Names’’ section of each entrylists both the systematic (IUPAC) and common names for acompound.

Many compounds also have another kind of name, abrand name or trade name given to them by their manufac-turers. For example, some trade names for the pain killeracetaminophen are PanadolTM, TylenolTM, AcetaTM, Gena-papTM, TempraTM, and DepacinTM. The symbol next to eachname means that the name is registered to the company thatmakes the compound. Trades names may be mentioned in theOverview or Uses sections of the entry for each compound.

Chemical Formula: A chemical formula is a set of sym-bols that tells the elements present in a compound and therelative numbers of each element. For example, the chemicalformula for the compound carbon dioxide is CO2. That for-mula tells that for every one carbon atom (C) in carbondioxide there are two atoms of oxygen (O).

Chemists use different kinds of formulas to describe acompound. The simplest formula is a molecular formula.A molecular formula like CO2 tells the kind and relativenumber of elements present in the compound. Another kindof formula is a structural formula. A structural formulaprovides one additional piece of information: The arrange-ment of elements in a compound. The structural formula formethanol (wood alcohol), for example, is CH3OH. That for-mula shows that methanol consists of a carbon atom (C) towhich are attached three hydrogen (H) atoms (CH3). Thecarbon atom is also joined to an oxygen atom (O) which, inturn, is attached to a hydrogen atom (H).

Structural formulas can be written in a variety of ways.Another way to draw the structural formula for methanol, forexample, is to show where individual bonds between atomsbranch off other atoms in different directions. These struc-tural formulas can be seen on the first page of nearlyall entries in Chemical Compounds. In a third type of struc-tural formula, the ball-and-stick formula, each element is

Reader ’s Guide

xiv CHEMICAL COMPOUNDS

represented by a ball of some size, shape, and/or color. Thechemical bond that holds them together is represented bysticks. This can be represented on paper in a drawing thatsimulates a three-dimensional model, by computer software,or actually in three dimensions from a kit with balls andsticks.

All three kinds of structural formulas are given for eachcompound described in this book. The only exception issome very large compounds known as polymers that containmany hundreds or thousands of atoms. In such cases, theformulas given shown only one small segment of thecompound.

Compound Type: Millions of chemical compounds exist.To make the study of these compounds easier, chemistsdivide them into a number of categories. Nearly all com-pounds can be classified as either organic or inorganic.Organic compounds contain the element carbon; inorganiccompounds do not. A few important exceptions to that ruleexist, as indicated in the description of such compounds.

Both organic and inorganic compounds can be furtherdivided into more limited categories, sometimes calledfamilies of compounds. Some families of organic compoundsare the hydrocarbons (made of carbon and hydrogen only),alcohols (containing the -OH group), and carboxylic acids(containing the -COOH groups). Many interesting and impor-tant organic compounds belong to the polymer family. Poly-mers consist of very large molecules in which a single smallunit (called the monomer) is repeated hundreds or thousandsof times over. Some polymers are made from two or, rarely,three monomers joined to each other in long chains.

Most inorganic compounds can be classified into one offour major groups. Those groups are the acids (all of whichcontain at least one hydrogen (H) atom), bases (which allhave a hydroxide (OH) group), oxides (which all have anoxygen (O)), and salts (which include almost everything else).A few organic and inorganic compounds described in thisbook do not easily fit into any of these families. They areclassified simply as organic or inorganic.

Molecular Weight: The molecular weight of a compoundis equal to the weight of all the elements of which it is made.The molecular weight of carbon dioxide (CO2), for example,is equal to the atomic weight of carbon (12) plus two times

CHEMICAL COMPOUNDS xv

Reader ’s Guide

the atomic weight of oxygen (2 x 16 = 32), or 44. Chemistshave been studying atomic weights and molecular weightsfor a long time, and the molecular weights of most com-pounds are now known with a high degree of certainty.The molecular weights expressed in this book are takenfrom the Handbook of Chemistry and Physics, 86th edition,published in 2005. The Handbook is one of the oldest, mostwidely used, and most highly regarded reference books inchemistry.

Melting Point and Boiling Point: The melting point of acompound is the temperature at which it changes from asolid to a liquid. Its boiling point is the temperature at whichit changes from a liquid to a gas. Most organic compoundshave precise melting points and/or, sometimes, precise boil-ing points. This fact is used to identify organic compounds.Suppose a chemist finds that a certain unknown compoundmelts at exactly 16.5�C. Reference books show that only asmall number of compounds melt at exactly that temperature(one of which is capryllic acid, responsible for the distinctiveodor of some goats). This information helps the chemistidentify the unknown compound.

Inorganic compounds usually do not have such precisemelting points. In fact, they may melt over a range of tem-peratures (from 50�C to 55�C, for example) or sublime with-out melting. Sublimation is the process by which a substancechanges from a solid to gas without going through the liquidphase. Other inorganic compounds decompose, or breakapart, when heated and do not have a true melting point.

Researchers often find different melting points and boil-ing points for the same compound, depending on the refer-ence book they use. The reason for this discrepancy is thatmany scientists have measured the melting points and boil-ing points of compounds. Those scientists do not always getthe same result. So, it is difficult to know what the ‘‘true’’ or‘‘most correct’’ value is for these properties. In this book, themelting points and boiling points stated are taken from theHandbook of Chemistry and Physics.

Some compounds, for a variety of reasons, have no spe-cific melting or boiling point. The term ‘‘not applicable’’ isused to indicate this fact.

Solubility: The solubility of a compound is its tendencyto dissolve in some (usually) liquid, such as water, alcohol, or

xvi CHEMICAL COMPOUNDS

Reader ’s Guide

acetone. Solubility is an important property because mostchemical reactions occur only when the reactants (the sub-stances reacting with each other) are dissolved. The mostcommon solvent for inorganic compounds is water. The mostcommon solvents for organic compounds are the so-calledorganic solvents, which include alcohol, ether, acetone, andbenzene. The solubility section in the entry for each com-pound lists the solvents in which it will dissolve well (listedas ‘‘soluble’’), to a slight extent (‘‘slightly soluble’’), or not atall (‘‘insoluble’’).

Overview: The overview provides a general introduc-tion to the compound, with a pronunciation of its name, abrief history of its discovery and/or use, and other generalinformation.

How It Is Made: This section explains how the compoundis extracted from the earth or from natural materials and/orhow it is made synthetically (artificially). Some productionmethods are difficult to describe because they include reac-tants (beginning compounds) with difficult chemical namesnot familiar to most people with little or no background inchemistry. Readers with a special interest in the synthesis(artificial production) of these compounds should consulttheir local librarian or a chemistry teacher at a local highschool or college for references that contain more informa-tion on the process in question. The For Further Informationsection may also contain this information.

Interesting Facts This section contains facts and tidbitsof information about compounds that may not be essential toa chemist, an inventor, or some other scientific specialist,but may be of interest to the general reader.

Common Uses and Potential Hazzards Chemical com-pounds are often of greatest interest because of the way theycan be used in medicine, industry, or some other practicalapplication. This section lists the most important uses ofeach compound described in the book.

All chemical compounds pose some risk to humans. Onemight think that water, sugar, and salt are the safest com-pounds in the world. But, of course, one can drown in water,become seriously overweight by eating too much sugar, anddevelop heart problems by using too much salt. The riskposed by a chemical compound really depends on a numberof factors, one of the most important of which is the amount

CHEMICAL COMPOUNDS xvii

Reader ’s Guide

of the compound to which one is exposed. The safest rule tofollow in dealing with chemical compounds is that they areALL dangerous under some circumstances. One should alwaysavoid spilling any chemical compound on the skin, inhalingits fumes, or swallowing any of the compound. If an accidentof this kind occurs, one should seek professional medicaladvice immediately. This book is not a substitute for promptfirst aid properly applied.

Having said all that, some compounds do pose moreserious health threats than others, and some individuals areat greater risks than others. Those special health risks arementioned toward the end of the ‘‘Common Uses and Poten-tial Hazards’’ section of each entry.

For Further Information As the name suggests, thissection provides ideas for books, articles, and Internetsources that provide additional information on the chemicalcompound listed.

ADDED FEATURES

Chemical Compounds contains several features to helpanswer questions related to compounds, their properties,and their uses.

• The book contains three appendixes: a list by formula,list by element contained in compounds, and list by typeof compound.

• Each entry contains up to two illustrations to show therelationship of the atoms in a compound to each other,one a black and white structural formula, and one acolor ball-and-stick model of a molecule or portion of amolecule of the compound.

• A chronology and timeline in each volume locates sig-nificant dates in the development of chemical com-pounds with other historical events.

• ‘‘For Further Information,’’ a list of useful books, periodi-cals, and websites, provides links to further learningopportunities.

• The comprehensive index, which appears in eachvolume, quickly points readers to compounds, people,and events mentioned throughout Chemical Com-pounds.

Reader ’s Guide

xviii CHEMICAL COMPOUNDS

ACKNOWLEDGMENTS

In compiling this reference, the editors have been fortunatein being able to rely upon the expertise and contributions ofthe following educators who served as advisors:

Ruth Mormon, Media Specialist, The Meadows School,Las Vegas, Nevada

Cathy Chauvette, Sherwood Regional Library, Alexan-dria, Virginia

Jan Sarratt, John E. Ewing Middle School, Gaffney, SouthCarolina

Rachel Badanowski, Southfield High School, Southfield,Michigan

The editors would also like to thank the artists of Pub-lishers Resource Group, under the lead of Farley Pedini, fortheir fast and accurate work and grace under pressure.

COMMENTS AND SUGGESTIONS

We welcome your comments on Chemical Compounds. Pleasewrite: Editors, Chemical Compounds, U•X•L, 27500 Drake Rd.,Farmington Hills, MI 48331; call toll-free 1-800-877-4253; fax,248-699-8097; or send e-mail via http://www.gale.com.

Reader ’s Guide

CHEMICAL COMPOUNDS xix

tim l of thetimeline of theveldevelopment

e icalof chemicalpoundscompounds

c. 3000 BCE • Egyptians develop a method for convertinggypsum to plaster of Paris, which is then used as mortarto join blocks in buildings.

c. 2700 BCE • Chinese documents mention sodium chlorideand the consumption of tea.

c. 1550 BCE • The analgesic properties of willow tree bark,from which salicylic acid comes, are described in Egyp-tian scrolls.

c. 1000 BCE • Ancient Egyptians use dried peppermint leaves.

800 BCE • Chinese and Arabic civilizations use borax for mak-ing glass and in jewelry work.

CHEMICAL COMPOUNDS

xxi

510 BCE • Persian emperor Darius makes the first recordedreference to sugar when he refers to the sugar canegrowing on the banks of the Indus River.

184 BCE • Roman writer Cato the Elder describes a method ofproducing calcium oxide.

c. 1st century CE • Roman philosopher Pliny the Elder writesabout a substance he calls hammoniacus sal, whichappears to have been ammonium chloride.

1st century CE • The first recipes calling for the use of pectinto make jams and jellies are recorded.

c. 575 CE • The cultivation of the coffee tree begins in Africa.

659 • Cinnamaldehyde is described in the famous Chinesemedical text, the Tang Materia Medica.

8th century • Arabian chemist Abu Musa Jabir ibn Hayyan,also known as Geber, writes about his work with severalcompounds, such as sodium chloride, sulfuric acid, nitricacid, citric acid, and acetic acid.

1242 • English natural philosopher Roger Bacon describes amethod for making gunpowder.

Late 1200s • First mention of camphor by a Westerner occursin the writings of Marco Polo.

4000 BCE 3000 BCE 2000 BCE 1000 BCE 1 CE 500

4000 BCE

Iron Age beginsin Egypt..

8TH CENTURYBCE

First recordedOlympic Games.

.

C. 6 BCE

Jesus ofNazarethis born..

622Mohammed’sflight from

Mecca to Medina..

Timeline of the Development of Chemical Compounds

xxii CHEMICAL COMPOUNDS

1300s • Potassium sulfate becomes known to alchemists.

1500s • Spanish explorers bring vanilla to Europe from Southand Central America, where it had already been used toflavor food.

1603 • Flemish chemist Jan Baptista van Helmont isolates anew gas produced during the combustion of wood, whichis eventually called carbon dioxide.

1608 • Potash is one of the first chemicals to be exported byAmerican colonists, with shipments leaving Jamestown,Virginia.

1610 • French alchemist Jean Beguin prepares acetone.

1620 • Flemish physician and alchemist Jan Baptista van Hel-mont first discovers nitric oxide.

1625 • German chemist Johann Rudolf Glauber is believed tohave been the first to produce hydrogen chloride in areasonably pure form. Later he is first to make ammo-nium nitrate artificially.

1695 • The term Epsom salts is introduced by British natura-list Nehemiah Grew, who names the compound after thespring waters near Epsom, England, from which it wasoften extracted.

1000 1200 1400 1500 1600 1700

1096 1099First Crusade

.

1215Magna Carta

accepted by KingJohn of England.

.

1492Christopher

Columbus sailsto the Americas.

.

1620Pilgrims land atPlymouth, Mass.

.

CHEMICAL COMPOUNDS xxiii


1700 • German chemist Georg Ernst Stahl extracts acetic acidfrom vinegar by distillation.

1702 • German chemist Wilhelm Homberg is believed to bethe first person to prepare boric acid in Europe.

1720s • German chemist Johann Schulze makes discoveries thatlead to using silver nitrate in printing and photography.

1746 • The first commercially successful method for makingsulfuric acid is developed.

1747 • German chemist Andreas Sigismund Marggraf isolatesa sweet substance from raisins that comes to be known asglucose.

1753 • James Lind reports that citrus fruits are the mosteffective means of preventing scurvy.

1769 • Oxalic acid is first isolated by German chemist JohannChristian Wiegleb.

1770s • British chemist Joseph Priestly does pioneering workwith the compounds carbon dioxide, carbon monoxide,hydrogen chloride, and nitrous oxide, among others.

1770s • Swedish chemist Karl Wilhelm Scheele discovers andworks with phosphoric acid, glycerol, lactic acid, andpotassium bitartrate.

1700 1710 1720 1730 1740 1750

1726Czar Peter the Great

of Russia dies..

1754French and Indian

War begins inNorth America.

.

xxiv CHEMICAL COMPOUNDS


1773 • French chemist Hilaire Marin Rouelle identifies ureaas a component of urine.

Late 1700s • Commercial production of sodium bicarbonateas baking soda begins.

1776 • Carbon monoxide is first prepared synthetically byFrench chemist Joseph Marie Francois de Lassone,although he mistakenly identifies it as hydrogen.

1790 • The first patent ever issued in the United States isawarded to Samuel Hopkins for a new and better way ofmaking pearl ash.

1794 • Ethylene is first prepared by a group of Dutchchemists.

Early 1800s • Silver iodide is first used in photography byFrench experimenter Louis Daguerre.

1817–1821 • French chemists Joseph Bienaime Caventou andPierre Joseph Pelletier successfully extract caffeine, qui-nine, strychnine, brucine, chinchonine, and chlorophyllfrom a variety of plants.

1817 • Irish pharmacist Sir James Murray uses magnesiumhydroxide in water to treat stomach and other ailments.The compound is eventually called milk of magnesia.

1760 1770 1780 1790 1800 1810

1776The U.S. Declarationof Independence is

signed..

1789French Revolution

.

1793Cotton gin isinvented byEli Whitney.

.

1811 1812Three severeearthquakes

occur near NewMadrid, Missouri.

.

1812.War of 1812

begins..

CHEMICAL COMPOUNDS xxv


1818 • Hydrogen peroxide is discovered by French chemistLouis Jacques Thenard.

1819 • French naturalist Henri Braconnot discovers cellulose.

1825 • British chemist and physicist Michael Faraday dis-covers ‘‘bicarburet of hydrogen,’’ which is later calledbenzene.

1830 • Peregrine Phillips, a British vinegar merchant fromEngland, develops the contact process for making sulfu-ric acid. In the early 21st century it is still the mostcommon way to make sulfuric acid.

1831 • Chloroform is discovered almost simultaneously byAmerican, French, and German chemists. Its use as ananesthetic is discovered in 1847.

1831 • Beta-carotene is first isolated by German chemist Hein-rich Wilhelm Ferdinand Wackenroder.

1834 • Cellulose is first isolated and analyzed by French bota-nist Anselme Payen.

1835 • Polyvinyl chloride is first discovered accidentally byFrench physicist and chemist Henry Victor Regnault.PVC is rediscovered (again accidentally) in 1926.

1810 1820 1830

1823U.S. presidentJames Monroeproclaims the

Monroe Doctrine..

1819U.S. acquiresFlorida from

Spain..

1831Cyrus McCormick’s

reaper is introduced..

1820The MissouriCompromiseis enacted..


xxvi CHEMICAL COMPOUNDS

1836 • British chemist Edmund Davy discovers acetylene.

1838 • French chemist Pierre Joseph Pelletier discoverstoluene.

1839 • German-born French chemist Henri Victor Regnaultfirst prepares carbon tetrachloride.

1839 • German druggist Eduard Simon discovers styrene inpetroleum.

1845 • Swiss-German chemist Christian Friedrich Schonbeindiscovers cellulose nitrate.

1846 • Americans Austin Church and John Dwight form acompany to make and sell sodium bicarbonate. The pro-duct will become known as Arm & Hammer� baking soda.

Mid 1800s • Hydrogen peroxide is first used commercially—primarily to bleach hats.

1850s • Oil is first discovered in the United States in westernPennsylvania.

1840 1850 1860

1850Levi Strauss

manufactureshis first pair

of jeans..

1846MexicanAmerican

War begins..

1858Lincoln debates

Douglas in Illinoissenate campaign.

.

1847Gold

discoveredin California..

CHEMICAL COMPOUNDS xxvii


1853 • French chemist Charles Frederick Gerhardt develops amethod for reacting salicylic acid (the active ingredientin salicin) with acetic acid to make the first primitiveform of aspirin.

1859 • Ethylene glycol and ethylene oxide are first preparedby French chemist Charles Adolphe Wurtz.

1860s • Swedish chemist Alfred Nobel develops a process formanufacturing nitroglycerin on a large scale.

1863 • TNT is discovered by German chemist Joseph Wil-brand, although the compound is not recognized as anexplosive until nearly 30 years later.

1865 • The use of carbolic acid as an antiseptic is first sug-gested by Sir Joseph Lister.

1865 • German botanist Julius von Sachs demonstrates thatchlorophyll is responsible for photosynthetic reactionsthat take place within the cells of leaves.

1870 • American chemist Robert Augustus Chesebroughextracts and purifies petrolatum from petroleum andbegins manufacturing it, eventually using the nameVaselineTM.

1873 • German chemist Harmon Northrop Morse rediscoversand synthesizes acetaminophen. It had been discoveredoriginally in 1852, but at the time it was ignored.

1860 1870 1880

1869Dmitri Mendeleev

formulates theperiodic law.

.

1876Alexander Graham

Bell patents thetelephone..

1861AmericanCivil War

starts..

1866Mendel

discovers lawsof heredity.

.

1884Worldwide systemof standard time

is adopted..

xxviii CHEMICAL COMPOUNDS


1879 • Saccharin, the first artificial sweetener discovered, issynthesized accidentally by Johns Hopkins researchersConstantine Fahlberg and Ira Remsen.

1879 • Riboflavin is first observed by British chemist Alex-ander Wynter Blyth.

1883 • Copper(I) oxide is the first substance found to havesemiconducting properties.

1886 • American chemist Charles Martin Hall invents amethod for making aluminum metal from aluminumoxide, which drastically cuts the price of aluminum.

1889 • French physiologist Charles E. Brown-Sequard per-forms early experiments on the effects of testosterone.

1890s • Commercial production of perchlorates begins.

1890s–early 1900s • British chemists Charles Frederick Cross,Edward John Bevan, and Clayton Beadle identify thecompound now known as cellulose. They also developrayon.

Late 1890s • Artificial methods of the production of purevanillin are developed.

1901 • The effects of fluorides in preventing tooth decay arefirst observed.

1890 1900 1910

1901The first Nobel

prizes are awarded..

1896Henry Ford

assembles thefirst motor car.

.

1888George Eastmanintroduces theKodak camera..

CHEMICAL COMPOUNDS xxix


1904 • German physicist Wilhelm Hallwachs discovers that acombination of copper metal and copper(I) oxide displaysthe photoelectric effect.

1910 • The first plant for the manufacture of rayon in theUnited States is built. By 1925 rayon becomes morepopular than silk.

1910 • Japanese scientist Suzuki Umetaro discovers thiamine.

1912 • Nicotinic acid is first isolated by Polish-American bio-chemist Casimir Funk.

1914–1917 • Ethylene glycol is manufactured for use in WorldWar I in explosives and as a solvent.

1914–1918 • A shortage of sugar during World War I leadsto the reintroduction of saccharin to sweeten food.Saccharin production would boom again during WorldWar II.

Late 1910s • Mustard gas is first used in war. Later it isfound to be effective in treating cancer in experimentalanimals.

1922 • Vitamin E is discovered by two scientists at the Uni-versity of California at Berkeley.

1910 1915 1920

1914 1918World War I

.

1919First man madenuclear reaction

occurs..

1905Einstein

formulatesthe theory of

relativity..

1912The Titanic

sinks on hermaiden voyage.

.

1922Soviet Union

comes intoexistance..

xxx CHEMICAL COMPOUNDS


1928 • Polymethylmethacrylate (PMMA) is first synthesizedin the laboratories of the German chemical firm Rohmand Haas.

1928 • Scottish bacteriologist Alexander Fleming accidentallydiscovers penicillin.

1930 • DuPont begins manufacturing dichlorodifluoro-methane under the name Freon�.

1930 • A polymer based on styrene is produced by researchersat the German chemical firm I. G. Farben. Polystyrenecomes to the United States in 1937.

1930s • Properties and methods of synthesizing many vita-mins, such as riboflavin, thiamine, niacin, ascorbic acid,pyridoxine, alpha-tocopherol, and retinol, are developed.

Early 1930s • SBS is first developed by German chemistsWalter Bock and Eduard Tschunkur.

1933 • British chemists Reginald Gibson and Eric Fawcettaccidentally re-discover polyethylene, which was firstdiscovered in 1889.

1935 • Nylon is invented by Wallace Carothers. It is used inconsumer products within three years.

1935 • German chemist Adolf Friedrich Johann Butenandtsynthesizes testosterone.

1925 1930 1935

1929The Great

Depressionbegins.

1927Charles Lindbergh

flies solo across theAtlantic Ocean.

.

CHEMICAL COMPOUNDS xxxi


1937 • German forensic scientist Walter Specht discovers thatblood can act as the catalyst needed to produce chemilu-minescence with luminol, a compound discovered in thelate 1800s.

1937 • Plexiglas� (made from polymethylmethacrylate) isexhibited at the World’s Trade Fair in Paris.

1937 • The basic process for making polyurethanes is firstdeveloped by German chemist Otto Bayer.

1937 • The cyclamate family of compounds is discovered byMichael Sveda, a graduate student at the University ofIllinois.

1938 • Polytetrafluoroethylene is invented by Roy J. Plunkettby accident at DuPont’s Jackson Laboratory.

1939 • Swiss chemist Paul Hermann Muller finds that DDT isvery effective as an insecticide, which makes it useful inpreventing infectious diseases such as malaria.

1939–1945 • During World War II, the U.S. military finds anumber of uses for nylon, polyurethanes, polystyrene,percholorates, and silica gel.

Early 1940s • Penicillin is first produced for human use andis valuable in saving the lives of soldiers wounded inWorld War II.

1935 1940 1945

1939World War II

begins..

1941First regular

televisionbroadcasts

begin..

1942Irving Berlinwrites song

‘‘WhiteChristmas.’’

.

1945U.S. dropstwo atomic

bombson Japan..

1946First

‘‘baby boomers’’are born..

xxxii CHEMICAL COMPOUNDS


1940s • A research chemist at the General Electric Company,E. G. Rochow, finds an efficient way of making organosi-loxanes in large quantities.

1941 • Folic acid is isolated and identified by Americanresearcher Henry K. Mitchell.

1941 • The first polyurethane adhesive, for the joining ofrubber and glass, is made.

1942 • American researchers Harry Coover and Fred Joinerdiscover cyanoacrylate.

1946 • DEET is patented by the U.S. Army for use on militarypersonnel working in insect-infested areas. It is madeavailable to the public in 1957.

1947 • On April 16, an ammonium nitrate explosion in TexasCity, Texas, becomes the worst industrial accident in U.S.

1950s • Earliest reports surface about athletes using testo-sterone to enhance their sports performance.

1950s • A stretchable material made of polyurethane, calledspandex, is introduced.

1951 • Phillips Petroleum Company begins selling polypropy-lene under the trade name of Marlex�.

1953 • Polycarbonate, polyethylene, and synthetic rubber aredeveloped.

1950 1955 1960

1953Molecular

structure of DNAis discovered.

.

1950Korean War

begins..

1955Jonas Salkinvents the

polio vaccine..

1958First satellite

broadcastsoccur..

CHEMICAL COMPOUNDS xxxiii


1955 • Proctor & Gamble releases the first toothpaste contain-ing stannous fluoride, Crest�.

Mid 1950s • Wham-O creates the hula-hoop—a ring of plasticthat is made with low-grade polyethylene.

1956 • British chemist Dorothy Hodgkin determines the che-mical structure of cyanocobalamin.

1958 • Scientist W. Barnes of the chemical firm T. & H. Smithin Edinburgh, Scotland, discovers denatonium benzoate.

Early 1960s • Ibuprofen is developed by researchers at theBoots Company, a British drug manufacturer.

1960s • Triclosan becomes a common ingredient in soaps andother cleaning projects.

1960s • MTBE is first synthesized by researchers at theAtlantic Richfield Corporation as an additive designedto increase the fuel efficiency of gasoline.

1962 • Amoxicillin is discovered by researchers at the Beechampharmaceutical laboratories.

1965 • Aspartame is discovered accidentally by James M.Schlatter.

1950 1960 1970

1975Vietnam War

ends..

1963U.S. President

John F. Kennedyis assassinated.

.

xxxiv CHEMICAL COMPOUNDS


1980s • A ceramic form of copper(I) oxide is found to havesuperconducting properties at temperatures higher thanpreviously known superconductors.

1980s • Polycarbonate bottles begin to replace the more cum-bersome and breakable glass bottles.

1987 • Procter & Gamble seeks FDA approval of sucrose polye-ster. Ten years pass before the FDA grants that approval.

1994 • The U.S. Food and Drug Administration approves thesale of naproxen as an over-the-counter medication.

1995 • On April 19, American citizens Timothy McVeigh andTerry Nichols use a truckload of ammonium nitrate andother materials to blow up the Alfred P. Murrah FederalBuilding in Oklahoma City, Oklahoma.

Early 2000s • Some 350,000 propane-powered vehicles existin the United States and about 4 million are used world-wide.

2004 • The leading chemical compound manufactured in theUnited States is sulfuric acid, with 37,515,000 metrictons (41,266,000 short tons) produced. Next is ethylene,with about 26.7 million metric tons (29.4 million shorttons) produced.

1980 1990 2000 2006

1991Soviet Unionis dissolved.

.

1989The oil tankerExxon Valdez

sinks offAlaska..

2001World Trade Center

in New York Cityis destroyed.

.

1981First personal

computersbecome

available..

CHEMICAL COMPOUNDS xxxv


or to owwords to know

•AACETYL The organic group of acetic acid.

ADHESIVE A substance used to bond two surfaces together.

ALCHEMY An ancient field of study from which the modernscience of chemistry evolved.

ALKALI A chemical base that can combine with an acid toproduce a salt.

ALKALINE A substance that has a pH higher than 7.

ALKALOID An organic base that contains the element nitrogen.

ALKANE A type of hydrocarbon that has no double bonds becauseit contains the maximum possible number of hydrogen

ALKENE A kind of hydrocarbon with at least one double bondbetween carbons.

ALKYL GROUP A chemical group containing hydrogen andcarbon atoms.

CHEMICAL COMPOUNDS

xxxvii

ALLOTROPE A form of an element that is different from itstypical form, with a different chemical bond structurebetween atoms.

AMIDE An organic compound that includes the CON groupbound to hydrogen.

AMINO ACID An organic compound that contains at least onecarboxyl group (-COOH) and one amino group (-NH2).They are the building blocks of which proteins are made.

ANALGESIC A substance the relieves pain.

ANHYDROUS Free from water and especially water that ischemically combined in a crystalline substance.

ANION A negatively charged ion.

ANODE The electrode in a battery in which electrons are lost(oxidized).

AROMATIC COMPOUND A compound whose chemical struc-ture is based on that of benzene (C6H6).

•BBIODEGRADABLE Something that can be easily broken down

by the action of bacteria.

BLOCK COPOLYMER A polymer composed of two or moredifferent polymers, each of which clumps in blocks ofidentical molecules.

BORATE A salt that contains boron.

BRINE Salt water; water with a large amount of salt dissolvedin it, such as seawater or water used to pickle vegetables.

BYPRODUCT A product that is made while making somethingelse.

Words to Know

xxxviii CHEMICAL COMPOUNDS

•CCARBOHYDRATES Organic compounds composed of carbon,

oxygen, and hydrogen, which are used by the body asfood.

CARBOXYL GROUPS Groups of atoms consisting of a carbonatom double bonded to an oxygen atom and singlebonded to a hydroxyl (-OH) group (–COOH).

CARCINOGEN A substance that causes cancer in humans orother animals.

CATALYST A material that increases the rate of a chemicalreaction without undergoing any change in its own che-mical structure.

CATHODE The electrode in a battery through which electronsenter the fuel cell.

CATION A positively charged ion.

CAUSTIC Capable of burning or eating away, usually by theaction of chemical reactions.

CENTRIFUGE A device that separates substances that havedifferent densities by using centrifugal force.

CHELATE A chemical compound that is in the form of a ring.It usually contains one metal ion attached to a minimumof two nonmetal ions by coordinate bonds.

CHEMILUMINESCENCE Light produced by a chemical reac-tion.

CHIRAL A molecule with different left-handed and right-handed forms; not mirror symmetric.

CHLOROFLUOROCARBONS (CFCS) A family of chemicalsmade up of carbon, chlorine, and fluorine. CFCs were usedas a refrigerant and propellant before they were bannedfor fear that they were destroying the ozone layer.

CHEMICAL COMPOUNDS xxxix

Words to Know

CHROMATOGRAPHY A process by which a mixture of sub-stances passes through a column consisting of somematerial that causes the individual components in themixture to separate from each other.

COAGULATE To make a liquid become a semisolid.

COENZYME A chemical compound that works along with anenzyme to increase the rate at which chemical reactionstake place.

COMPOUND A substance formed of two or more elementsthat are chemically combined.

COPOLYMER A polymer made from more than one type ofmonomer.

COVALENT COMPOUND A compound in which the atoms arebonded to each other by sharing electrons.

CROSS-LINKED Polymer chains that are linked together tocreate a chemical bond.

CRYOGENICS The study of substances at very low tempera-tures, using substances such as liquefied hydrogen orliquefied helium.

•DDECOMPOSE To break a substance down into its most basic

elements.

DENATURED To be made not fit for drinking.

DERIVATIVE Something gotten or received from anothersource.

DESICCANT Chemical agent that absorbs or adsorbs moisture.

DIATOMIC Composed of two atoms.

DISACCHARIDE A compound formed by the joining of twosugar molecules.

xl CHEMICAL COMPOUNDS

Words to Know

DISPERSANT A substance that keeps another substance fromclumping together or becoming lumpy.

DISTILLATION A process of separating liquid by heating itand then condensing its vapor.

•EELASTOMER A polymer known for its flexibility and elastic

qualities; a type of rubber.

ELECTRODE A conductor through which an electric currentflows.

ELECTROLYSIS A process in which an electric current is usedto bring about chemical changes.

ELECTROLYTE A substance which, when dissolved in water,will conduct an electric current.

EMULSIFIER A substance that combines two other substancestogether that do not usually mix together and ensuresthey are spread evenly.

ESTER A compound formed by the reaction between an acidand an alcohol.

EXOTHERMIC Accompanied by the freeing of heat.

•FFAT An ester formed in the reaction between glycerol

(C3H5(OH)3) and a fatty acid, an organic acid with morethan eight carbon atoms.

FERROUS Containing or made from iron.

FLOCCULANT A type of polymer, or large man-made particle,that is created by a repetitive chain of atoms.

FLUOROCARBON A chemical compound that contains carbonand fluorine, such as chlorofluorocarbon.

CHEMICAL COMPOUNDS xli

Words to Know

FOSSIL FUEL A fuel, such as petroleum, natural gas, or coal,formed from the compression of plant and animal matterunderground millions of years ago.

FREE RADICAL An atom or group of atoms with a singleunpaired electron that can damage healthy cells in thebody.

•GG/MOL Grams per mole: a measure of molar mass that indi-

cates the amount of the compound that is found in amole of the compound. The molecular weight (also knownas relative molecular mass) is the same number as themolar mass, but the g/mol unit is not used.

GLOBAL WARMING The increase in the average global tem-perature.

GLUCONEOGENESIS The production of glucose from non-carbohydrate sources, such as proteins and fats.

GLYCOGEN A carbohydrate that is stored in the liver andmuscles, which breaks down into glucose.

GREENHOUSE EFFECT The increase of the average globaltemperature due to the trapping of heat in the atmo-sphere.

•HHARD WATER Water with a high mineral content that does

not lather easily.

HELIX A spiral; a common shape for protein molecules.

HORMONE A chemical that delivers messages from one cellor organ to another.

HYDRATE A chemical compound formed when one or moremolecules of water is added physically to the molecule ofsome other substance.

xlii CHEMICAL COMPOUNDS

Words to Know

HYDROCARBON A chemical compound consisting of onlycarbon and hydrogen, such as fossil fuels.

HYDROGENATION A chemical reaction of a substance withmolecular hydrogen, usually in the presence of a catalyst.

HYDROLYSIS The process by which a compound reacts withwater to form two new compounds.

•I

INCOMPLETE COMBUSTION Combustion that occurs in such away that fuel is not completely oxidized.

INERT A substance that is chemically inactive.

INORGANIC Relating to or obtained from nonliving things.

ION An atom or molecule with an electrical charge, eitherpositive or negative.

IONIC BOND A force that attracts and holds positive andnegative ions together.

IONIC COMPOUND A compound that is composed of positiveand negative ions, so that the total charge of the positiveions is balanced by the total charge of the negative ions.

ISOMER Two or more forms of a chemical compound with thesame molecular formula, but different structural formu-las and different chemical and physical properties.

ISOTOPE A form of an element with the usual number ofprotons in the nucleus but more or less than the usualnumber of electrons.

•KKREBS CYCLE A series of chemical reactions in the body that

form part of the pathway by which cells break downcarbohydrates, fats, and proteins for energy. Also calledthe citric acid cycle.

CHEMICAL COMPOUNDS xliii

Words to Know

•LLATENT Lying hidden or undeveloped.

LEACH Passing a liquid through something else in order todissolve minerals from it.

LEWIS ACID An acid that can accept two electrons and form acoordinate covalent bond.

LIPID An organic compound that is insoluble in water, butsoluble in most organic solvents, such as alcohol, ether,and acetone.

•MMEGATON A unit of explosive force equal to one million

metric tons of TNT.

METABOLISM All of the chemical reactions that occur in cellsby which fats, carbohydrates, and other compounds arebroken down to produce energy and the compoundsneeded to build new cells and tissues.

METALLURGY The science of working with metals and ores.

METHYLXANTHINE A family of chemicals including caffeine,theobromine, and theophylline, many of which are sti-mulants.

MINERALOGIST A scientist who studies minerals.

MISCIBLE Able to be mixed; especially applies to the mixingof one liquid with another.

MIXTURE A collection of two or more elements or compoundswith no definite composition.

MONOMER A single molecule that can be strung togetherwith like molecules to form a polymer.

xliv CHEMICAL COMPOUNDS

Words to Know

MONOSACCHARIDE A simple sugar, made up of three to ninecarbon atoms.

MORDANT A substance used in dyeing and printing thatreacts chemically with both a dye and the material beingdyed to help hold the dye permanently to the material.

•NNARCOTIC An addictive drug that relieves pain and causes

drowsiness.

NEUROTRANSMITTER A chemical that relays signals alongneurons.

NEUTRALIZE To make a substance neutral that is neitheracidic or alkaline.

NITRATING AGENT A substance that turns other substancesinto nitrates, which are compounds containing NO3.

NSAID Non-steroidal anti-inflammatory drug, a drug that canstop pain and prevent inflammation and fever but that isnot a steroid and does not have the same side effects assteroids.

•OORGANIC Relating to or obtained from living things. In

chemistry, refers to compounds made of carbon com-bined with other elements.

OXIDANT A substance that causes oxidation of a compoundby removing electrodes from the compound. Also knownas oxidizing agent.

OXIDATION STATE The sum of negative and positive charges,which indirectly indicates the number of electronsaccepted or donated in the bond between elements.

CHEMICAL COMPOUNDS xlv

Words to Know

OXIDIZE To combine a substance with oxygen, or to removehydrogen from a molecule using oxygen, or to removeelectrons from a molecule.

•PPARTICULATE MATTER Tiny particles of pollutants sus-

pended in the air.

PETROCHEMICALS Chemical compounds that form in rocks,such as petroleum and coal.

PH (POTENTIAL HYDROGEN) The acidity or alkalinity of asubstance based on its concentration of hydrogen ions.

PHOSPHATE A compound that is a salt of phosphoric acid,which consists of phosphorus, oxygen, sometimes hydro-gen, and another element or ion.

PHOTOELECTRIC EFFECT The emission of electrons by a sub-stance, especially metal, when light falls on its surface.

PHOTOSYNTHESIS The process by which green plants andsome other organisms using the energy in sunlight toconvert carbon dioxide and water into carbohydrates andoxygen.

PHOTOVOLTAIC EFFECT A type of photoelectric effect wherelight is converted to electrical voltage by a substance.

PLASTICIZER A substance added to plastics to make themstronger and more flexible.

POLYAMIDE A polymer, such as nylon, containing recurrentamide groups linking segments of the polymer chain.

POLYMER A substance composed of very large moleculesbuilt up by linking small molecules over and over again.

POLYSACCHARIDE A very large molecule made of many thou-sands of simple sugar molecules joined to each other inlong, complex chains.

xlvi CHEMICAL COMPOUNDS

Words to Know

PRECIPITATE A solid material that settles out of a solution,often as the result of a chemical reaction.

PRECURSOR A compound that gives rise to some other com-pound in a series of reactions.

PROPRIETARY Manufactured, sold, or known only by theowner of the item’s patent.

PROSTAGLANDINS A group of potent hormone-like sub-stances that are produced in various tissues of thebody. Prostaglandins help with a wide range of physiolo-gical functions, such as control of blood pressure,contraction of smooth muscles, and modulation of inflam-mation.

PROTEIN A large, complex compound made of long chains ofamino acids. Proteins have a number of essential func-tions in living organisms.

•QQUARRY An open pit, often big, that is used to obtain stone.

•RREAGENT A substance that is employed to react, measure, or

detect with another substance.

REDUCTION A chemical reaction in which oxygen is removedfrom a substance or electrons are added to a substance.

REFRACTORY A material with a high melting point, resistantto melting, often used to line the interior of industrialfurnaces.

RESIN A solid or semi-solid organic material that is used tomake lacquers, adhesives, plastics, and many other clearsubstances.

CHEMICAL COMPOUNDS xlvii

Words to Know

•SSALT An ionic compound where the anion is derived from an acid.

SEMICONDUCTOR A material that has an electrical conduc-tance between that of an insulator and a conductor.When charged with electricity or light, semiconductorschange their state from nonconductive to conductive orvice versa.

SEQUESTERING AGENT A substance that binds to metals inwater to prevent them from combining with other com-ponents in the water and forming compounds that couldstain (sequestering agents are sometimes used in clean-ing products). Also called a ‘‘chelating agent.’’

SILICATE A salt in which the anion contains both oxygen andsilicon.

SOLUBLE Capable of being dissolved in a liquid such as water.

SOLUTION A mixture whose properties and uniform through-out the mixture sample.

SOLVENT A substance that is able to dissolve one or moreother substances.

SUBLIME To go from solid to gaseous form without passingthrough a liquid phase.

SUPERCONDUCTIVITY A state in which a material loses allelectrical resistance: once established, an electrical cur-rent will flow forever.

SUPERCOOLED WATER Water that remains in liquid form,even though its temperature is below 0�C.

SUSPENSION A mixture of two substances that do not dis-solve in each other.

SYNTHESIZE To produce a chemical by combining simplerchemicals.

xlviii CHEMICAL COMPOUNDS

Words to Know

•TTERATOGENIC Causing birth defects; comes from the Greek

word ‘‘teratogenesis,’’ meaning ‘‘monster-making.’’

THERMAL Involving the use of heat.

TOXIC Poisonous or acting like a poison.

TOXIN A poison, usually produced by microorganisms or byplants or animals.

TRAP A reservoir or area within Earth’s crust made of non-porous rock that can contain liquids or gases, such aswater, petroleum, and natural gas.

•UULTRAVIOLET LIGHT Light that is shorter in wavelength than

visible light and can fade paint finishes, fabrics, andother exposed surfaces.

•VVASODILATOR A chemical that makes blood vessels widen,

reducing blood pressure.

VISCOUS Having a syrupy quality causing a material to flowslowly.

VITRIFICATION The process by which something is changedinto glass or a glassy substance, usually by heat.

VOLATILE Able to turn to vapor easily at a relatively lowtemperature.

•WWATER OF HYDRATION Water that has combined with a

compound by some physical means.

CHEMICAL COMPOUNDS xlix

Words to Know

OTHER NAMES:Biethylene; bivinyl;divinyl; erythrene;

vinylethylene

FORMULA:CH2=CHCH=CH2

ELEMENTS:Carbon, hydrogen

COMPOUND TYPE:Alkene (unsaturated

hydrocarbon)

STATE:Gas

MOLECULAR WEIGHT:54.09 g/mol

MELTING POINT:�108.91�C

(�164.04�F)

BOILING POINT:�4.41�C (�24.1�F)

SOLUBILITY:Insoluble in water;soluble in alcohol,

ether, and benzene

1,3-Butadiene

KE

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OVERVIEW

1,3-butadiene (one-three-byoo-tah-DYE-een) is a colorlessgas with a mild, slightly sweet odor. It occurs naturally inpetroleum, from which it is extracted at refineries. The com-pound was first discovered in petroleum in 1886 by theEnglish chemist Henry E. Armstrong (1848–1937) and hiscolleague A. K. Miller (no dates available). This discoveryapparently had no practical application until 1910 when theRussian chemist Sergei Lebedev (1874–1934) developed amethod for polymerizing butadiene to make a rubber-likesubstance. Even then, Lebedev’s invention, called polybuta-diene, was primarily a laboratory curiosity. There was rela-tively little demand for rubber products that could not bemet by the vast supplies of natural rubber from SoutheastAsia.

That situation began to change in the 1920s and 1930s.The demand for rubber products in automobiles and othermotor vehicles, especially tires, grew rapidly as car and truckproduction increased rapidly year after year. At the same

H H

C C

CC

HH

H H

CHEMICAL COMPOUNDS 1

time, manufacturers began to worry about losing their sup-ply of natural rubber from traditional suppliers in Java,Malaysia, Sumatra, and other parts of Asia. As a result,chemists in Europe and the United States began to look forsynthetic substitutes for natural rubber. Lebedev’s discoveryprovided one solution to this problem, and butadiene-basedsynthetic rubber products were soon flowing from manufac-turing plants.

HOW IT IS MADE

Butadiene is made by three processes in the UnitedStates. The first two of those processes begin with four-carbon compounds called butane (CH3CH2CH2CH3) andbutene (CH2=CHCH2CH3 and CH3CH=CHCH3). These com-pounds are treated in one of two ways so as to add one moredouble bond to the molecules, resulting in the formation of1,3-butadiene (CH2=CHCH=CH2). The third and most commonprocess is known as steam cracking. Steam cracking is aprocess by which large petroleum molecules are exposed tovery hot steam, causing them to break apart into smallermolecules. Steam cracking is the method by which ethylene,the most important organic chemical produced in the UnitedStates, is made. 1,3-butadiene is a by-product of this process,and is separated from the major product, ethylene, aftercracking is complete.

1,3 Butadiene. White atoms arehydrogen and black atoms arecarbon. Gray sticks indicatedouble bonds. P U B L I S H E R S

R E S O U R C E G R O U P

2 CHEMICAL COMPOUNDS

1,3 BUTADIENE

COMMON USES AND POTENTIAL HAZARDS

Virtually all of the 1,3-butadiene produced is used in themanufacture of polymers. Polybutadiene itself is too soft formost industrial rubber uses. So it is sometimes mixed withother polymers to make products with a variety of desirablequalities. Or it is polymerized with other monomers to makespecialized copolymers. One of the most popular of the mixedpolymers is polystyrene-polybutadiene. The second polymerin this mixture, polystyrene, is a polymer of the compoundstyrene (C6H5CH=CH2). Some other uses of 1,3-butadieneinclude:

• Raw material in the manufacture of fungicides such asCaptan and Captofol;

• Manufacture of latex adhesives;

• Production of domestic products, such as the backingon nylon carpet, appliance and electrical equipment,and luggage;

• Manufacture of industrial products, such as piping andconduits.

1,3-butadiene has a variety of harmful effects on humans,including irritation of the respiratory system, fatigue, drow-siness, headache, vertigo, loss of consciousness, respiratoryparalysis, and death. The compound is also thought to be acarcinogen. Only people who work directly with the com-pound, however, are likely to experience such effects, andonly then in unusual situations. The average person is likelyto have no contact with the compound.

Interesting Facts

• In 2004, U.S. manufac-turers produced 2.2 millionmetric tons (2.4 millionshort tons) of 1,3-buta-diene, ranking it number

22 among all chemicalsproduced in the UnitedStates.


1,3 BUTADIENE

FOR FURTHER IN FORMAT ION

‘‘1,3 Butadiene.’’ National Safety Council.http://www.nsc.org/library/chemical/13 Butad.htm (accessedSeptember 14, 2005).

‘‘1,3 Butadiene Health Effects.’’ Occupational Safety & HealthAdministration.http://www.osha.gov/SLTC/butadiene/healtheffects.html(accessed September 14, 2005).

Johnson, Peter S. Rubber Processing: An Introduction. Cincinatti,OH: Hanser Gardner Publications, 2001.

‘‘ToxFAQs for 1,3 Butadiene.’’ Agency for Toxic Substances andDisease Registry.http://www.atsdr.cdc.gov/tfacts28.html (accessed September14, 2005).

See Also Styrene

Words to Know

CARCINOGEN A substance that causescancer in humans or other animals.

COPOLYMER A polymer made with twodifferent monomers.

POLYMER A compound consisting of verylarge molecules made of one or two smallrepeated units called monomers.

POLYMERIZING The process by whichpolymers are made.


1,3 BUTADIENE

OTHER NAMES:Mustard gas; see

Overview for morenames

FORMULA:(CH2CH2Cl)2S

ELEMENTS:Carbon, hydrogen,

chlorine, sulfur

COMPOUND TYPE:Organic sulfide

STATE:Liquid


MELTING POINT:13 to 14�C (55 to 57�F)

BOILING POINT:217�C (423�F)


ether, acetone,benzene, and other

organic solvents;soluble in fats

2,20-DichlorodiethylSulfide

KE

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AC

TS

OVERVIEW

2,20-dichlorodiethyl sulfide (two-two-prime-di-KLO-ro-di-ETH-el sul-fyd) is more commonly known as mustard gas. Itis also known as bis-(2-chloroethyl) sulfide; sulfur mustard;yprite; and 1,10-thiobis[2-chloroethane]. The compound occursas a yellowish liquid that, in a pure form, has no odor. Smallamounts of impurities give it the distinctive odor of mus-tard, from which it gets its common name. It may also smelllike garlic or horseradish because of impurities.

Mustard gas was discovered by the English physicistFrederick Guthrie (1833–1886) in 1860. While working withthe compound, Guthrie spilled mustard gas on his skin andfound that it produced a painful red blister. That propertyhas led to the primary use of mustard gas, as a chemicalagent used in warfare. When sprayed on a person, the com-pound can blister the skin, burn the eyes, and irritate thelungs. In large doses, it can kill a person. Mustard gas wasfirst used as a chemical weapon on July 12, 1917 by theGerman army in an attack on Canadian soldiers at Ypres,

C CSC CCl Cl

H HH H

H HH H


Belgium. An estimated 20,000 troops were killed in theattack. By the end of World War I, an estimated 120,000British troops had died as a result of mustard gas attacks.

The damage caused by mustard gas was due at least inpart because troops had no means of protecting themselvesagainst the compound. It was able to penetrate virtually anytype of protective clothing then available. The damagecaused by mustard gas is so horrible that most nationshave agreed not to use it in wars. One exception may haveoccurred during the Iraq-Iran war of 1980–1988, whenthe Iraqis sprayed Iranian troops with a gas very much likemustard gas in 1984. Later, in 1987 and 1988, Iraq’s rulerSaddam Hussein also used mustard gas against Kurdish peo-ple living in northern Iraq.

HOW IT IS MADE

The usual method for making mustard gas in the UnitedStates is called the Levenstein process. In this process, ethy-lene gas (CH2=CH2) is bubbled through sulfur chloride (S2Cl2),a yellowish-red oil with a very strong odor. In Germany andother nations, the compound is made by treating the organiccompound 2,20-dihydroxyethyl sulfide with hydrochloric acid.


Virtually the only use for mustard gas is as a chemicalagent in warfare. But, interestingly enough, the compound

2,20

Dichlorodiethyl Sulfide.

White atoms are hydrogen;black atoms are carbon; greenatoms are chlorine; and yellow

atom is sulfur. P U B L I S H E R S



2,20 DICHLORODIETHYL SULFIDE

has been used in one other very different way: in the treat-ment of cancer. The husband and wife medical team of E.B.and H.D. Krumbhaar discovered in 1919 that mustard gas waseffective in treating cancer in experimental animals. (Theycalled the compound by its then-popular name, yellow crossgas.) The compound was one of the first chemicals to be usedin the treatment of cancer. Researchers continued to studythe cancer-fighting properties of mustard gas for more thantwenty years, but the compound has never been widely usedfor that purpose.

The effects of exposure to mustard gas vary over time. Atfirst, a person who has inhaled the gas may become nau-seated, experience itchy and sore eyes, and begin vomiting.His or her skin turns red and blisters may develop. Exposureto large amounts of the gas may result in permanent damageto the eyes and respiratory system resulting, in the worstcases, in coma and death. People exposed to mustard gas whosurvive may later develop mouth, lung, or stomach cancer.

Interesting Facts

• Another name for mustardgas, yprite, comes fromthe Belgian city Ypres(pronounced ‘‘EE-pr’’’),where the compound wasfirst use as a militaryweapon.

• The use of mustard gaswas outlawed by theChemical WeaponsConvention, adopted in1993. The United Statesstarting destroying itsstockpile of mustard gaseven earlier, in 1985, and isnow thought to have noneof the chemical agent left.

• Mustard gas was not usedduring World War II. Thecompound was, nonethe-less, responsible for thedeaths of more than 100U.S. men. On December 2,1943, a German attack onthe harbor of Bari, Italy,resulted in the sinking ofabout two dozen ships.Some of those ships werecarrying mustard gas.When they sank, theyreleased the gas into thesurrounding water, wheresurvivors inhaled andswallowed the poisonouscompound.




‘‘Molecule of the Month: Mustard Gas.’’ Bristol University.http://www.chm.bris.ac.uk/motm/mustard/mustard.htm (accessedon September 13, 2005).

‘‘Mustard Gas.’’ International Progamme on Chemical Safety.http://www.inchem.org/documents/pims/chemical/mustardg.htm (accessed on September 13, 2005).

Strobel, Warren P. ‘‘Saddam’s Lingering Atrocity.’’ U.S. News &World Report (November 27, 2000): 52.

‘‘ToxFAQs for Sulfur Mustard.’’ Agency for Toxic Substances andDisease Registry.http://www.atsdr.cdc.gov/tfacts49.html (accessed on September13, 2005).



OTHER NAMES:Ibuprofen; see Over-

view for more names

FORMULA:C13H18O2


oxygen

COMPOUND TYPE:Organic acid

STATE:Solid


MELTING POINT:76�C (169�F)

BOILING POINT:Not applicable;

decomposes abovemelting point

SOLUBILITY:Slightly soluble in

water; soluble in mostorganic solvents

2-(4-Isobutylphenyl)-propionic Acid

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OVERVIEW

2-(4-Isobutylphenyl)propionic acid (two four eye-so-BYOO-tuhl-PHEEN-uhl PRO-pi-on-ik AS-id) is a colorless crystallinesolid widely used as an analgesic and anti-inflammatory medi-cation. It is most commonly known as ibuprofen, but is alsoknown as a-methyl-4-(2-methylpropyl)benzeneacetic acid and4-isobutyl-@alpha;-methylphenylacetic acid. It is also soldunder a variety of trade names, including Aches-n-Pain�,Advil�, Andran�, Antagil�, Antarene�, Excedrin IB�, Gen-pril�, Ibuprin�, Medipren�, Midol�, Motrin�, Nuprin�,PediaProfen�, Rufen�, and Vicoprofen�.

Ibuprofen was developed by researchers at the BootsCompany, a British drug manufacturer, in the early 1960s.Those researchers had found that the anti-inflammatoryproperty of aspirin was due to the presence of a carboxylicacid (-COOH) group in the compound. They searched for othercarboxylic acids that might have similar properties and,after testing more than 600 compounds, discovered thatibuprofen met that criterion. It was twice as effective as

C

C

OH

H

H

H

H H

H H

CCC

C CC

CC OH

CH3H3C

H3C


acetylsalicylic acid (aspirin), the standard against which theywere testing their products. They initially called their dis-covery ‘‘Brufen.’’

In 1974, Boots licensed the Upjohn Company in theUnited States to begin making a commercial version ofBrufen. Upjohn called its product Motrin and marketed thecompound primarily to people with arthritis. It soon becamea popular drug with both doctors and patients, who foundthey were able to control the pain of arthritis with a non-addictive product that was easier on the stomach thanaspirin.

Boots also entered the U.S. market several years later,selling ibuprofen under the trade name of Rufen. A numberof other drug companies were eager to begin marketing theirversion of ibuprofen, and when the U.S. Food and DrugAdministration approved ibuprofen for over-the-counter

2 (4 isobutylphenyl)

propionic acid. Red atoms areoxygen; white atoms are

hydrogen; and black atomsare carbon. Gray sticks indicate

double bonds. Striped sticksindicate a benzene ring.

P U B L I S H E R S R E S O U R C E G R O U P


2 (4 ISOBUTYLPHENYL)PROPIONIC ACID

sales, they were ready. Whitehall Laboratories introducedAdvil and Upjohn and Bristol-Meyers jointly released Nuprin.After Boots’ patent ran out in 1985, several other drug manu-facturers began producing their own versions of the popularpain-killing and anti-inflammatory product.

HOW IT IS MADE

The original method for making ibuprofen developed byBoots researchers begins with 2-methylpropylbenzene, acompound with a four-carbon methylpropyl group attachedto a benzene ring. 2-methylpropybenzene is a readily avail-able product with a molecular structure quite similar to thatof ibuprofen. Then, in a series of six steps, various groupsof atoms are added, removed, or transposed to produce the2-(4-isobutylphenyl)propionic acid molecule.

Other methods for preparing ibuprofen have also beendeveloped. One of the most recent procedures has beeninvented by green chemists. Green chemists are chemistswho look for methods of making chemical compounds thatare less wasteful of raw materials, more sensitive to environ-mental concerns, and less hazardous to human health. Thegreen chemistry method of making ibuprofen also beginswith 2-methylpropylbenzene, but uses different catalystsand fewer steps to produce ibuprofen. Overall, the greenmethod of making ibuprofen is twice as efficient (half asmuch waste products) as the original Boots method.


Ibuprofen is a nonsteroidal anti-inflammatory drug,or NSAID. The term nonsteroidal indicates that ibuprofenis not a steroid, a common class of drugs used to reduce

Interesting Facts

Some evidence suggests thattaking ibuprofen for twoyears or more may reduce

the risk of developingAlzheimer’s disease.



inflammation and swelling. Scientists believe that ibuprofenworks by inhibiting the enzyme cyclooxygenase (COX),which converts arachidonic acid to prostaglandins. Arachido-nic acid is a naturally occurring fatty acid that is used tobuild a number of important biochemical compounds, includ-ing the prostaglandins. The prostaglandins are involved inthe transmission of pain impulses throughout the nervoussystem. If the COX enzyme is prevented from functioning,arachidonic acid can not be converted into prostaglandins,and pain messages will not be transmitted.

Ibuprofen is especially effective in treating certain kindsof pain and inflammation, including those associated withmenstrual cramps, various kinds of arthritis, headaches andmigraines, pain from injuries and surgery, and discomfortassociated with influenza and gout.

The major risk associated with use of ibuprofen is sto-mach irritation. The inventors of ibuprofen had hoped tofind a substance that causes less stomach irritation thanaspirin. Ibuprofen does seem to cause fewer gastrointestinalproblems than does aspirin. Nevertheless, it can still causesevere problems in some patients, especially those who takelarge doses. Common complaints from the use of ibuprofeninclude nausea, stomach pain, and diarrhea. Patients whoare especially sensitive or who take high doses of ibuprofenfor long periods may experience damage to the stomachlining.

As with any drug, some patients should avoid takingibuprofen entirely. These include individuals with heartor kidney problems, people who are taking so-called ‘‘bloodthinners,’’ pregnant women during the last three months of

Words to Know

ANALGESIC a substance the relieves pain.

CATALYST a material that increases therate of a chemical reaction withoutundergoing any change in its ownchemical structure.

GREEN CHEMISTRY the practice of makingchemical compounds that are less wastefulof raw materials, more sensitive toenvironmental concerns, and lesshazardous to human health.



pregnancy, people with asthma, and people who are allergicto aspirin.


‘‘Ibuprofen.’’ Chemical Land 21.http://www.chemicalland21.com/arokorhi/lifescience/phar/IBUPROFEN.htm (accessed on November 3, 2005).

‘‘Ibuprofen Oral.’’ MedicineNet.com.http://www.medicinenet.com/ibuprofen oral/article.htm(accessed on November 3, 2005).

Rainsford, K. D., ed. Ibuprofen: A Critical Bibliographic Review.

Bethesda, MD: CCR Press, 1999.

See Also Acetylsalicylic Acid



OTHER NAMES:Methyltrinitroben-

zene; TNT

FORMULA:C6H2(CH3)(NO2)3


nitrogen, oxygen

COMPOUND TYPE:Substituted aromatic

hydrocarbon(organic)

STATE:Solid



BOILING POINT:Decomposes

explosively at 240�C(460�F)


ether, acetone, andbenzene

2,4,6-Trinitrotoluene

KE

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TS

OVERVIEW

2,4,6-trinitrotoluene (two four six try-nye-troh-TOL-yoo-een), or TNT, is a yellow odorless solid that occurs in the formof crystalline needles. Its major use is in the manufactureof explosives. It may be used alone or in combination withother explosive chemicals. Although not as powerful as someother explosives, it has the advantage of being relativelyinsensitive to shock. Workers can handle the explosive with-out fear that it will suddenly explode if dropped or jarred. Infact, a blasting cap or detonator is needed to cause TNT toexplode. Blasting caps and detonators are very sensitiveexplosives that can be attached to less sensitive explosiveslike TNT. Any small shock to the blasting cap or detonatorwill cause it to explode. That explosion, in turn, causes theless sensitive explosive, such as TNT, to blow up.

TNT was discovered by the German chemist Joseph Wil-brand (1811–1894) in 1863, although the compound was notrecognized as an explosive until almost thirty years later.The compound was first produced commercially in Germany

CC

C

C

CC

H3C

NO2

NO2

NO2


in 1901 and first used by Germany and its enemies duringWorld War I. The explosive became so popular during the warthat production of TNT could not keep up with demand byarmies on both sides of the conflict.

HOW IT IS MADE

The method developed by Wilbrand for manufacturingTNT is simple, efficient, and inexpensive, and remains the

2,4,6 Trinitrotoluene. Redatoms are oxygen; white atomsare hydrogen; black atoms are

carbon; and blue atoms arenitrogen. Gray sticks indicatedouble bonds. Striped sticks

indicate a benzene ring.P U B L I S H E R S R E S O U R C E G R O U P


2,4,6 TRINITROTOLUENE

primary process by which TNT is produced today. Wilbrandmade TNT by adding nitric acid (HNO3) and sulfuric acid(H2SO4) to toluene (C6H5CH3).


By far the most common use of TNT is in the manufac-ture of explosives. Until the discovery of nuclear energy inthe 1940s, TNT was the most powerful explosive known tohumans. Today, TNT is often combined with other explosivesto make even more powerful bombs. Some examples includethe following:

• Torpex, a mixture of TNT, wax and aluminum used inunderwater explosives, such as those found in torpe-does. Torpex is about 50 percent more powerful thanpure TNT;

• Pentolite, a combination of TNT and pentaerythritoltetranitrate (PETN) used primarily in blasting capsand detonators;

• Military dynamite, which contains the explosive RDX,TNT, motor oil, and cornstarch, is less powerful thanpure dynamite, but much safer to handle;

Interesting Facts

• During World War I (1914–1918), people who madeexplosives for the military(usually women and girls)were sometimes called‘‘canary girls.’’ Their namecame from the fact thattheir skin turned yellowwhen exposed to solidTNT. Women with red hairalso found their hair turn-ing an orangish or gingercolor because of exposureto TNT.

• TNT has become the stan-dard for explosive powerin the world today. Whensomeone talks about a‘‘15 kiloton bomb’’ they arereferring to a bomb withthe explosive equivalent of15 thousand (‘‘kilo’’) tons ofTNT. Nuclear weaponscommonly have explosivepowers rated in the kilotonor megaton (million tonsof TNT) range.



• Amatol, a combination of TNT and ammonium nitrate,is often substituted for TNT in ordnance (weapons);

• Minol, a variation of amatol that includes 20 percentaluminum to increase its explosive power; and

• Baratol, a mixture of TNT and barium nitrate thatexplodes more slowly than pure TNT.

In addition to its primary use in explosives, 2,4,6-tri-nitrotoluene is also used to produce a very attractive yellowtint in the manufacture of dyes and photographic chemicals.

2,4,6-trinitrotoluene is a hazardous chemical that can pro-duce both short- and long-term health effects, such as respira-tory problems, skin irritation, anemia, and lung damage. Someresearch shows the compound may be carcinogenic in labora-tory animals, but not in humans. Since most people are neverexposed to TNT, these hazards are primarily of concern to menand women engaged in the manufacture or use of TNT.


Cooper, P. W., and S. R. Kurowski. Introduction to the Technology

of Explosives. New York: Wiley VCH, 1997.

‘‘Public Health Statement for 2,4,6 Trinitrotoluene.’’ Agency forToxic Substances and Disease Registry.http://www.atsdr.cdc.gov/toxprofiles/phs81.html (accessedSeptember 15, 2005).

Words to Know

CARCINOGEN A chemical that causes cancerin humans or other animals.



OTHER NAMES:See Overview.

FORMULA:CH3CONHC6H4OH


oxygen, nitrogen

COMPOUND TYPE:Aromatic amide

(organic)

STATE:Solid


MELTING POINT:169�C–172�C

(336�F–342�F)

BOILING POINT:Not applicable(decomposes)

SOLUBILITY:Insoluble in cold

water; more solublein warm water;

soluble in alcohol,acetone, and other

organic solvents

Acetaminophen

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OVERVIEW

Acetaminophen (uh-SEE-toe-Min-oh-fen) is one of themost commonly used analgesics in the world. It is also knownas p-Acetylaminophenol; p-acetamidophenol; N-acetyl-p-ami-nophenol; p-hydroxyacetanilide; and paracetamol. It is aningredient in more than 100 commercial products includingAbensanil�, Acamol�, Acetagesic�, Alpinyl�, Alvedon�,Anaflon�, Anelix�, Anhiba�, Calpol�, Datril�, Dirox�,Doliprane�, Dymadon�, Enelfa�, Eneril�, Exdol�, Febrilix�,Febrolin�, Fendon�, Finimal�, Hedex�, Homoolan�,Lonarid�, Multin�, Panadol�, Phendon�, Tylenol�, Valdol�,and Valgesic�. Acetaminophen is often combined with otheringredients in medications such as cold and flu products,cough suppressants, and allergy medications in order to treatmore than one symptom at a time.

Acetaminophen was first discovered in 1852 by theFrench chemist Charles Frederic Gerhardt, who also discov-ered aspirin a year later. His results were largely ignored,however, until a German chemist, Harmon Northrop Morse

H

CH3

C

CC C

CC

C

O

OH

N

H

HH

H


(1848–1920) re-discovered and synthesized the compound in1873. Even then, the medicinal qualities of the compoundwere not appreciated for another twenty years, and the com-pound was not even prescribed or used by doctors until 1949.Since that time, however, it has become extremely popular,exceeded only by aspirin as the most popular analgesic soldin the world.

HOW IT IS MADE

Acetaminophen is made in a straight-forward reactionbetween p-aminophenol [C6H4(OH)(NH2)] and acetic anhy-dride [(CH3CO)2O]. As its formula shows, the p-aminophenolprovides the basic structure from which acetaminophen isformed, with the acetic anhydride adding the -CH3CO groupof atoms needed to complete the compound.


In addition to its use as a pain reliever, acetaminophenhas a number of industrial uses, including:

Acetaminophen. Red atomsare oxygen; white atoms arehydrogen; black atoms arecarbon; and blue atom is

nitrogen. Gray sticks indicatedouble bonds. P U B L I S H E R S



ACETAMINOPHEN

• Stabilizer for hydrogen peroxide solutions, to preventthe peroxide from breaking down too quickly;

• Raw material in the production of other pharmaceuticalcompounds;

• Raw material in the manufacture of photographic che-micals; and

• Raw material in the production of azo dyes, dyes thatcontain nitrogen atoms at the core of their molecules

Acetaminophen is generally regarded as so safe that any-one can purchase it without a prescription. The drug is notentirely without its hazards, however. People who take largequantities of acetaminophen are at some risk for liverdamage. That risk is especially great for anyone who drinksexcessive amounts of alcohol. Alcohol by itself damages theliver and, in conjunction with acetaminophen, that damagecan be serious. Some manufacturers now include a message

Interesting Facts

In September 1982, sevenindividuals in the Chicagoarea died after taking a formof Tylenol� called ExtraStrength Tylenol�. Officialslater found that someone hadadded cyanide to theTylenol� bottles. It was the

poison and not the pain killerthat had caused the deaths.The crime was never solved,but it led to the introductionof so called tamper proofpackaging for virtually allmedicines.

Words to Know

ANALGESIC A substance that relieves pain.

SYNTHESIS A chemical reaction in whichsome desired chemical product is made

from simple beginning chemicals, orreactants.


ACETAMINOPHEN

on the labels of their acetaminophen bottles about the risk ofexcessive ingestion of alcohol and acetaminophen.


Kaplan, Tamara. ‘‘The Tylenol Crisis: How Effective Public RelationsSaved Johnson & Johnson.’’http://www.personal.psu.edu/users/w/x/wxk116/tylenol/crisis.html (accessed on September 14, 2005).

Keenan, Faith. ‘‘Blocking Liver Damage.’’ Business Week (October21, 2002): 147.

MedlinePlus Drug Information, Acetaminophen.http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a681004.html (accessed on September 15, 2005).

Paracetamol Information Center.http://www.pharmweb.net/pwmirror/pwy/paracetamol/pharmwebpic.html (accessed on September 15, 2005).


ACETAMINOPHEN

OTHER NAMES:Ethanoic acid;

methanecarboxylicacid; vinegar acid

FORMULA:CH3COOH


oxygen

COMPOUND TYPE:Carboxylic acid

(organic)

STATE:Liquid


MELTING POINT:16.6�C (61.9�F)

BOILING POINT:117.9�C (244.2�F)

SOLUBILITY:Soluble in water,

alcohol, ether,acetone, benzene,and other organic

solvents

Acetic Acid

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OVERVIEW

Acetic acid (uh-SEE-tik AS-id) is a clear, colorless liquidwith a sharp odor. In its pure form, the compound is alsoknown as glacial acetic acid. Acetic acid is the primary activeingredient of vinegar, which typically consists of about fiveparts of acetic acid mixed with 95 parts of water. The com-pound’s name comes from the Latin word for vinegar, acetum.

Acetic acid, in the form of vinegar, has been known tohumans for centuries. When fruit juices are allowed to standfor too long, or when they are fermented to make wine,vinegar forms. The use of vinegar as a condiment is men-tioned a number of times in the Bible, and was described bythe Greek natural philosopher Theophrastus (c. 372–c. 287 BCE).The first person to extract acetic acid from vinegar wasthe Muslim alchemist Jabir ibn Hayyan Geber (c. 721–815).The pure compound was not produced, however, for anotherten centuries when the German chemist Georg Ernst Stahl(1660–1734) extracted acetic acid from vinegar in 1700 bydistillation.

COHO

CH3


More than 1.4 million metric tons (1.5 million short tons)of acetic acid are produced in the United States annually. Thelargest fraction of that amount is used as a raw material inthe manufacture of plastics.

HOW IT IS MADE

The most common method of making acetic acid is onedeveloped by the Monsanto chemical corporation. In thisprocess, synthesis gas (a mixture of carbon monoxide [CO]and hydrogen [H2]) is heated over a catalyst of copper metalmixed with zinc oxide to make methanol (methyl alcohol;CH3OH). The methanol is then treated with carbon monoxide(CO) to make acetic acid. Acetic acid can also be made by thefermentation of any material that contains sugar or someother carbohydrate. Although this method is of interest froma historical standpoint, it is not sufficiently efficient to useindustrially.

Acetic acid. Red atoms areoxygen; black atoms are carbon;and white atoms are hydrogen.

The oxygen atom at top leftshares a double bond withthe nearby carbon atom.



ACETIC ACID

Researchers are constantly looking for new, more efficient,more environmentally-friendly methods for making acetic acid.In 2003, for example, chemists at the University of SouthernCalifornia reported on a new method for making acetic aciddirectly from methane gas (CH4) using a catalyst of palladiumand sulfuric acid. Other researchers are looking for ways to oxidizethe waste gases produced from industrial processes to acetic acid.


Acetic acid is probably best known to most people as vine-gar. In this form, it is used as a condiment and a food preserva-tive. The greatest volume of acetic acid is used, however, in avariety of chemical processes, especially the manufacture ofplastic materials such as polyvinyl acetate (PVA), polyethyleneterephthalate (PET), and cellulose acetate. A more recent use ofacetic acid is in the manufacture of calcium magnesium acetate(CMA), a deicer. Traditionally, roads, highways, and airportrunways have been treated with calcium chloride (CaCl2) orsome other salt to remove snow and ice. These compounds haveserious environmental effects, however, and researchers havelong been looking for alternatives that are as effective inremoving snow and ice, but less harmful to the environment.CMA has been the most promising of these alternatives, and itsproduction has produced a growing demand for acetic acid.Some other applications of acetic acid include:

• As a cleaning agent;

• In the manufacture of photographic materials;

Interesting Facts

Ancient Romans boiledfermented wine (vinegar) inlead pots to make a sweetsyrup called sapa. The aceticacid in the vinegar dissolved asmall amount of lead fromwhich the pots were made,producing lead acetate

(Pb[C2H3O2]). When they usedsapa as a sweetening agentin their foods, the Romansingested the lead acetatewhich, over long periods oftime, caused the lead poisoning from which so many ofthem died.


ACETIC ACID

• For the production of a variety of organic compounds,such as those used in the manufacture of packagingmaterials, paints, adhesives and artificial fibers;

• As a fumigant (pesticide) to preserve fruits and grains;

• In the printing of textiles; and

• As an acidifier to improve the flow of oil from wells.

Dilute acetic acid in the form of vinegar is harmless andhas been consumed by humans for centuries. Prolonged con-tact with the skin or eyes may, however, produce irritation oftissues and should be avoided. Concentrated forms of aceticacid pose more serious health risks, such as irritation of thegastrointestinal system, respiratory system, and eyes. Mostpeople do not come into contact with the concentrated acid,and safety precautions are of importance only to individualswho handle the material in their work.


‘‘Acetic Acid.’’ Chemical of the Week.http://scifun.chem.wisc.edu/chemweek/AceticAcid/AceticAcid.html (accessed on September 16, 2005).

‘‘Acetic Acid and CMA.’’ https://netfiles.uiuc.edu/mcheryan/www/cma.htm (accessed on September 16, 2005).

‘‘Acetic Acid and Derivatives.’’ Kirk Othmer Encyclopedia of Che

mical Technology, 4th ed. Vol. 1. New York: John Wiley & Sons,1991, pp. 121 175.

See Also Amyl acetate; butyl acetate; ethyl acetate; isoamylacetate

Words to Know

ALCHEMY An ancient field of study fromwhich the modern science of chemistryevolved.

CATALYST A material that increases the rateof a chemical reaction without undergoingany change in its own chemical structure.

DISTILLATION A process of separatingtwo or more substances by boiling themixture of which they are composedand condensing the vapors producedat different temperatures.


ACETIC ACID

OTHER NAMES:Ethyne; ethine

FORMULA:CH=CH


COMPOUND TYPE:Alkyne (unsaturated

hydrocarbon;organic)

STATE:Gas


MELTING POINT:�80.8�C (�113�F)

BOILING POINT:�84�C (�120�F)

SOLUBILITY:Slightly soluble inwater and alcohol;soluble in acetone

and benzene

Acetylene

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OVERVIEW

Acetylene (uh-SET-ill-ene) is the simplest hydrocarbon,consisting of two carbon atoms joined to each other by atriple bond with their associated hydrogen atoms. It occursas a colorless gas with a sweet odor when pure, but anunpleasant odor due to the presence of phosphine (PH3)and/or arsine (AsH3), with which it is often contaminated.Acetylene is a highly flammable gas that is also somewhatexplosive. This property accounts for one of its most impor-tant uses, in torches that burn at very high temperatures.

Acetylene was discovered by the British chemistEdmund Davy (1785–1857) in 1836. Davy obtained the gasaccidentally when he combined water with potassium carbide(KCH2) while attempting to make potassium metal. He notedthat the gas burned with a bright flame and thought itmight be used as a source of illumination. That applicationwas impractical, however, because of the high cost of potas-sium carbide. When the German chemist Frederich Wohler(1800–1882) discovered the far less expensive calcium carbide

H HC C


(CaC2) in 1862, however, that problem was solved, and thedemand for acetylene in lamps and other applications grewrapidly.

HOW IT IS MADE

The original method of making acetylene by the action ofwater on calcium carbide was abandoned when more efficientmethods of synthesis became available. One of those methods,known as the Wulff process, involves the cracking of hydro-carbons from petroleum. In this process, liquid petroleum,which consists of many different kinds of hydrocarbons,is heated with very hot steam, causing the hydrocarbons tobreak apart (‘‘crack’’) into smaller compounds. Acetylene isone of these compounds.

A later improvement on this procedure was developed bythe German chemist Walter Reppe (1892–1969), sometimescalled the Father of Acetylene Chemistry. Since Reppeworked at that time for the BASF chemical corporation, theprocess is also known as the BASF process of making acet-ylene. In this procedure, hydrocarbons from petroleum aretreated with an oxidizing agent that causes them to breakapart to form smaller compounds, one of which, again, isacetylene.


By far the most important use of acetylene is in themanufacture of other chemicals, such as vinyl chloride, viny-lidene chloride, vinyl acetate, acrylonitrile, trichloroethylene

Acetyline. White atoms arehydrogen and black atoms arecarbon. Gray sticks indicatedouble bonds. P U B L I S H E R S



ACETYLENE

and perchloroethylene, and the family of plastics known asthe acrylates. (The name vinyl refers to the remnant of anacetylene molecule after one hydrogen atom has beenremoved: -CH2=CH-.) About 20 percent of all the acetyleneproduced is used for torches that produce very hot flames.In one such torch, the oxyacetylene torch, acetylene gasand oxygen are mixed and ignited at the tip of the torch.The combination of gases burns at a temperature of 3,000�Cto 3,500�C (5,500�F to 6,300�F). Oxyacetylene torches areused to cut through metal and to weld two metals to eachother. They can be used in very cold climates and even underwater.

Acetylene is both very flammable and explosive. Any-one who works with the compound or uses it in any formshould know how to use the device that contains the gas.Acetylene also has the somewhat unusual chemical propertyof reacting with certain metals, such as copper and silver, toform highly explosive compounds known as acetylides.Lamps, torches, and other devices built to hold and dispenseacetylene can not contain any of these metals. High concen-trations of the gas also pose a health hazard to humans. Itis classified as an asphyxiant, a gas that can produce dis-orientation, unconsciousness, and death when inhaled toexcess.

Interesting Facts

Acetylene was used asa source of illuminationbeginning in the early1900s. In one type ofacetylene lamp, water wasallowed to drop on a solidchunk of calcium carbide at acontrolled rate. The acetyleneproduced then passed into anignition chamber, where itburned with a brilliant whitelight. Acetylene lamps were

used in a variety of settings,such as the source of lightfor bicycles and early motorcars and as a source ofillumination for miners.Some small towns even usedacetylene lamps as theirmajor source of town lighting.Acetylene lamps continue tobe a popular collectors itemamong antique dealers today.


ACETYLENE


‘‘Acetylene Properties, Purity and Packaging.’’http://www.c f c.com/specgas_products/acetylene.htm(accessed on September 16, 2005).

‘‘The Environmental Impact of Acetylene Compared to Impact ofPropane Chemtane 2.’’ Chemtane.http://www.chemtane2.com/environmental/cva_env_impact.html (accessed on September 16, 2005).

O’Hara, Kelly. ‘‘Chemistry Hall of Fame 1997 Acetylene.’’ YorkUniversity.http://www.chem.yorku.ca/hall_of_fame/essays97/acetylene/acetylen.htm (accessed on September 16, 2005).

‘‘Oxy acetylene Welding and Cutting.’’ ESAB.http://www.esabna.com/EUWeb/OXY_handbook/589oxy2_1.htm (accessed on September 16, 2005).

See Also Polyvinyl chloride

Words to Know

OXIDATION A chemical reaction in whichoxygen reacts with some other substanceor, alternatively, in which some substancesloses electrons to another substance, theoxidizing agent.

SYNTHESIS A chemical reaction in whichsome desired chemical product is madefrom simple beginning chemicals, orreactants.


ACETYLENE

OTHER NAMES:Aspirin; see Overview

for more names

FORMULA:CH3COOC6H4COOH


oxygen


(organic)

STATE:Solid


MELTING POINT:135�C (275�F;decomposes)

BOILING POINT:Not applicable


alcohol, ether,chloroform

Acetylsalicylic Acid

KE

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OVERVIEW

Acetylsalicylic acid (uh-SEE-till-sal-in-SILL-ik As-id, or uh-se-TEEL-sal-ih-SEEL-ik AS-id), more commonly known asaspirin, is the world’s most commonly used therapeutic drug.By one estimate, about 137 million aspirin tablets are takenevery day throughout the world. The drug is also known byother names including: o-acetoxybenzoic acid; 2-(acetyloxy)-benzoic acid; 2-carboxyphenyl acetate; and benzoic acid,2-hydroxyacetate, in addition to about ten other systematicnames and many common names.

The analgesic properties of willow tree bark, from whichsalicylic acid comes, have been known for well over 3,500years. They were first described in Egyptian scrolls dating toabout 1550 BCE and were later recommended by a number ofancient authorities, including the famous Greek physicianHippocrates (c. 460–370 BCE), the Roman encyclopedist AulusCornelius Celsus (c. 10 BCE–date of death unknown), theRoman philosopher Pliny the Elder (23 CE–CE), and the Greekphysician Pedanius Dioscorides (40–90 CE).

C O

C

C

OH

H

H

H

C C

O

C C OH

CH3

C


In the period from 1828 to 1829, the active ingredient inwillow bark was first isolated by three individuals, the Ger-man pharmacist Johann Buchner (dates not available), theFrench chemist Henri Leroux (dates not available), and thethe Italian chemist, Raffaele Piria (1815–1865). Buchner gavethe name salicin to the bitter-tasting yellow crystalsextracted from willow bark after the Latin name for thewillow tree, Salix. In 1853, the French chemist Charles Fre-derick Gerhardt (1816–1857) developed a method for reactingsalicylic acid (the active ingredient in salicin) with aceticacid to make the first primitive form of aspirin.

Acetylsalicylic acid. Red atomsare oxygen; white atoms are

hydrogen; and black atoms arecarbon. Striped sticks indicate a

benzene ring. P U B L I S H E R S


ACETYLSALICYLIC ACID


For many years the way aspirin works in the body was notunderstood. Scientists now know that the compound’s helpfuleffects come from its action on prostaglandins. Prostaglandinsare hormone-like substances released by cells that are injured.They cause the body to release other substances that sensitizenerve endings to pain and start the healing process. Aspirinblocks prostaglandin production, thus relieving the sensationof pain and the inflammation that are the body’s response toinjury. Aspirin reduces fever by acting on the region of thebrain that regulates body temperature and heart rate. Prosta-glandins block the body’s natural system for producing heatso that by blocking the release of prostaglandins, aspirinallows the regulation of body temperature to continue asusual. Aspirin’s protection against heart attack and strokeoccur because of its effect on one special type of prostaglan-din, known as thromboxane A2. Thromboxane A2 promotesthe accumulation of cells that takes place when a blood clotforms. By blocking or slowing down the production of throm-boxane A2, aspirin prevents the formation of blood clots and,hence, the probability of heart attack and stroke.

HOW IT IS MADE

The modern method for making aspirin was developed in1897 by the German chemist Felix Hoffman (1868–1946), anemployee of the German chemical manufacturer Bayer AGChemical Works. In this procedure, phenol (C6H5OH) is treatedwith sodium hydroxide and carbon dioxide to make salicylic

Interesting Facts

• The name aspirin comesfrom a very old name forsalicylic acid, spiraeic acid.

• After Hofmann’s discov-ery, Bayer received aregistered trademark forthe name aspirin, meaningthat no other companycould use the name for

acetylsalicylic acid. WhenGermany was defeated inWorld War I (1914–1918),Allied forces seized theBayer company’s propertyand possessions and madethe name available to alldrug manufacturers.



acid. The salicylic acid is then reacted with acetic acid(CH3COOH) to make acetylsalicylic acid, or aspirin. The prepara-tion of aspirin by this procedure is quite simple and is oftenassigned to students in beginning high school and college chem-istry classes. Aspirin tablets themselves include only acetylsa-licylic acid, to which is added a small amount of water, starchand lubricant that act as a binder to hold the tablet together.


The exclusive use of aspirin is as a medicine. It has threeimportant properties as a drug. It relieves pain, reducesinflammation, and reduces fever. In addition to its effective-ness in treating these medical symptoms, it is inexpensiveand available in a variety of forms, including chewabletablets, extended-release formulations, effervescent tablets,and even in chewing gums. Aspirin is often prescribed in low,daily doses as a preventative measure for individuals at riskfor heart attack and stroke.

While aspirin has many medical benefits, it is not with-out risk for some individuals. Some people are allergic to thecompound and can not tolerate even a low dose. Such indivi-duals experience a number of symptoms if they ingest highdoses of aspirin, symptoms that include ringing in the ears,nausea, vomiting, dizziness, confusion, hallucinations, coma,seizures, rapid breathing, fever, and, in the most severecases, death. Aspirin use is not recommended in childrenunder the age of twelve who show symptoms of viral infec-tions because it can lead to an extremely rare but deadlycomplication known as Reye’s syndrome.


Arnst, Catherine. ‘‘A Preemptive Strike against Cancer.’’ Business

Week (June 7, 2004): 48.

Words to Know

ANALGESIC A substance that relieves pain. THERAPEUTIC Having healing properties.



‘‘Aspirin.’’ Plant Derived Drugs.http://phytomedical.com/Plant/Aspirin.asp (accessed on September 17, 2005).

Jeffreys, Diarmuid. Aspirin: The Remarkable Story of a Wonder

Drug. New York: Bloomsbury, 2004.

‘‘Molecule of the Month: Aspirin.’’http://www.bris.ac.uk/Depts/Chemistry/MOTM/aspirin/aspirin.htm (accessed on September 17, 2005).

See Also Acetaminophen




FORMULA:C29H50O


oxygen

COMPOUND TYPE:Organic

STATE:Liquid


MELTING POINT:2.5�C to 3.5�C (36�F to

38�F)

BOILING POINT:350�C (660�F;

decomposes)


ether, acetone, oils,and most organic

solvents

Alpha-Tocopherol

KE

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OVERVIEW

Alpha-tocopherol (AL-fa toe-KOF-er-ol) is also knownas 2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)chroman-6-ol and 3,4-Dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyl-tridecyl)-2H-1-benzopyran-6-ol, as well as by many othersystematic names. It is one of a family of compounds, thetocopherols, that makes up vitamin E. Other members of thefamily include the beta (b), gamma (g), delta (d), and epsilon(E) tocopherols. All tocopherols share the same basic molecu-lar structure, differing only in slightly different arrange-ments of methyl (CH3-) and hydroxyl (OH-) groups. In termsof biological activity, a-tocopherol is the most importantmember of the tocopherol family. The tocopherols are all paleyellow, viscous oils found in a variety of plants, includingalmonds, mustard greens, green and red peppers, spinach,and sunflower seeds. The most important source for thevitamin is wheat germ.

Vitamin E was discovered in 1922 by two scientists at theUniversity of California at Berkeley, Herbert McLean Evans

C C

C OC C

C

C C

C CCCHO

CH3

CH3

CH3

C

C C

CH3

C

C

C C

CH3

CH3

CH3H3C

C

C

H

H

H

H

H

H H

HH

HH

H H

H H

H

H

H H

H

H

H

H

HH


(1882–1971) and Katherine Scott Bishop (1889–1976). Evansand Bishop found that rats whose diet was deficient ina-tocopherol did not reproduce normally. Scientists are nowaware that the primary function of vitamin D in the humanbody is as an antioxidant. An antioxidant is a substance thatreacts with and prevents the harmful effects of chemicalstrictures known as free radicals. A free radical is an atomor group of atoms with a single unpaired electron, makingthe atom or atoms unusually reactive. Free radicals arethought to be a primary cause of cell damage leading tocardiovascular disease, cancer, and aging.

Vitamin E was first produced synthetically (artificially)in 1938 by Swiss chemist Paul Karrer (1889–1971), who hadbeen awarded the Nobel Prize in chemistry a year earlier forhis studies of vitamin A, vitamin B2, and other importantbiological compounds.

HOW IT IS MADE

A variety of methods is now available for the synthesis(artificial production) of the tocopherols. In the most com-monly used procedure, 2,3,5-trimethylhydroquinone is reactedwith isophytol over one of many possible catalysts. A smallamount of the vitamin is still obtained from natural sources,usually as the by-product in the treatment of one of itsnatural sources.

Alpha tocopheryl. Red atomsare oxygen; white atoms are

hydrogen; and black atoms arecarbon. P U B L I S H E R S



ALPHA TOCOPHEROL


Vitamin E deficiency disorders are rare in humans. Thevast majority of people get all the vitamin E they need intheir daily diets. Three groups of people may, however,require vitamin E supplements. The first group consists ofindividuals who are unable to absorb fat in their diets, sothat the vitamin E they ingest is immediately eliminatedfrom their bodies. The second group consists of a smallfraction of people who have genetic disorders that make itimpossible for them to utilize a-tocopherol. The third groupof individuals consist of premature and very young babies.All babies are born deficient in vitamin E, but they normallyovercome that deficiency in the first few weeks of their lives.Premature babies and some babies born at term may experi-ence a variety of health problems as a result of vitamin Edeficiency. Lack of normal reflexes, inability to orient itself,muscle weekness, and loss of balance are typical symptomsof vitamin E deficiency in babies. Deficiency problems forindividuals in all three groups can be overcome by takingsupplementary vitamin E.

Interesting Facts

As a general rule, vitaminsand minerals are equallypotent (effective) whether theycome from natural sources orsynthetic procedures. VitaminE is an exception to thatgeneral rule. Synthetic formsof the vitamin are generallyless potent than naturalforms. The reason for thisfact is that natural vitamin Eexists in only one stereoisomeric form. Stereoisomers are two or moreforms of a compound withthe same kind and numberof atoms. But the atoms instereoisomers have some

what different orientationsin space. These slight differences in geometric shapeare responsible for slightdifferences in biologicalactivity. Natural vitamin Econsists of only one stereoisomer, which is very activebiologically. Synthetic vitamin E consists of twostereoisomers, only one ofwhich (the one that occursin natural vitamin E) is biologically active. So syntheticvitamin E tends to be abouthalf as active biologically asnatural vitamin E.


ALPHA TOCOPHEROL

In addition to its use as a vitamin supplement for normalindividuals and those at risk for vitamin E deficiency, thetocopherols have a few other uses:

• In the curing of meat to block the action of nitrosa-mines, a group of compound that occurs naturally inmeats and may be carcinogenic;

• As an additive to animal feed to replace vitamins lostduring feed processing; and

• As a food additive in vegetable oils and shortening toprevent oxidation (spoilage).


Challem, Jack, and Melissa Diane Smith. Basic Health Publica

tions User’s Guide to Vitamin E: Don’t Be a Dummy: Become

an Expert on What Vitamin E Can Do for Your Health. NorthBergen, NJ: Basic Health Publications, 2002.

Packer, Lester, and Carol Colman. The Antioxidant Miracle: Put

Lipoic Acid, Pycogenol, and Vitamins E and C to Work for You.

New York: Wiley, 1999.

‘‘Vitamin E.’’ National Institutes of Health, Office of DietarySupplements.http://ods.od.nih.gov/factsheets/vitamine.asp (accessed onSeptember 17, 2005).

‘‘Vitamin E (tocopherol).’’ Vitamin and Health Supplements Guide.http://www.vitamins supplements.org/vitamin E.php(accessed on September 17, 2005).

Words to Know


VISCOUS Describes a syrupy liquid thatflows slowly.


ALPHA TOCOPHEROL

OTHER NAMES:Aluminum trifluoride

FORMULA:AlF3

ELEMENTS:Aluminum, fluorine

COMPOUND TYPE:Inorganic salt

STATE:Solid


MELTING POINT:1291�C (2356�F; begins

to sublime above1250�C [2280�F])



cold water, soluble inhot water; insolublein alcohol, acetone,

and most organicsolvents

Aluminum Fluoride

KE

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AC

TS

OVERVIEW

Aluminum fluoride (uh-LOO-min-um FLOR-ide) is a highlystable compound that occurs as a white crystalline solid. Itresists the action of even strong solvents, such as hot con-centrated sulfuric acid. The compound often occurs as ahydrate containing one or more molecules of water of hydra-tion. The most common of these hydrates has the chemicalformula AlF3�3.5H2O, meaning that for every two moleculesof aluminum fluoride in a crystal, there are seven moleculesof water. The major uses of aluminum fluoride are in avariety of applications in the chemical industry.

HOW IT IS MADE

Three methods are available for the preparation of alu-minum fluoride commercially. In the first method, aluminatrihydrate (aluminum hydroxide; Al(OH)3) is treated withhydrofluoric acid (HF). A second method of preparation isalmost identical except that it takes place in the dry state

F F

F

Al


between dry alumina trihydrate and gaseous hydrogen fluor-ide. The third method involves the addition of fluorosilicicacid (H2SiF6) to alumina trihdrate. The last of these methodsis commercially attractive because fluorosilicic acid isobtained inexpensively as a by-product in the production offertilizers and phosphoric acid.


The primary use of aluminum fluoride is in the produc-tion of aluminum metal. In that process, aluminum isextracted from one of its compounds (usually aluminumoxide) by passing an electric current through the molten(melted) compound. The addition of aluminum fluoride tothe raw materials used in the process reduces the temperatureat which the reaction occurs and improves the conductivity ofthe molten compound.

Some other uses of aluminum fluoride include:

• As a catalyst in the synthesis of organic compounds;

• To suppress the process of fermentation in the wine-and beer-making industries;

Aluminum fluoride. Red atomis aluminum and green atoms

are fluorine. P U B L I S H E R S



ALUMINUM FLUORIDE

• In the manufacture of ceramics and glass; and

• As a flux in the preparation of glazes, enamels and inmetallurgical processes.

Most authorities agree that aluminum fluoride does notpose a health hazard when ingested in moderate amountsbecause of its low solubility. The compound may pose athreat if inhaled or deposited on the skin, however. In mod-est amounts, it may produce skin and eye irritations thatrange from moderate to severe; irritation of the nose, throat,and lungs, that may include nosebleeds; and asthma-like

Interesting Facts

Controversy exists about thehealth hazards of aluminumfluoride. On the one hand,the compound would appearto pose a relatively minorrisk when ingested becauseit is so insoluble in waterand other solvents. If it doesnot dissolve in the body, itcan not get into the blood

stream. On the other hand,it can cause health problemsif inhaled or deposited onthe skin. Opponents ofwater fluoridation arguethat aluminum fluoride issufficiently toxic to humansthat it should not be addedto public water supplies.

Words to Know

FLUX A material that lowers the melting pointof another substance or mixture ofsubstances or that is used in cleaninga metal.

HYDRATE A chemical compound formedwhen one or more molecules of water isadded physically to the molecule of someother substance.


WATER OF HYDRATION Water that hascombined with a compound by somephysical means.


ALUMINUM FLUORIDE

symptoms with coughing, shortness of breath, and tightnessin the chest. Long-term exposure may result in weakness ofthe bones and stiffening of the joints.


‘‘Aluminum Fluoride.’’ ChemExper Chemical Directory.http://www.chemexper.com/chemicals/supplier/cas/7784 18 1.html (accessed on September 18, 2005).

‘‘Aluminum Fluoride.’’ Chemical Land 21.http://www.chemicalland21.com/industrialchem/inorganic/ALUMINUM%20FLUORIDE.htm (accessed on September 18,2005).

‘‘Aluminum Fluoride.’’ Solvay Chemicals.http://www.solvaychemicals.us/pdf/Inorganic_Fluorides/ALF.pdf (accessed on September 18, 2005).


ALUMINUM FLUORIDE


FORMULA:Al(OH)3

ELEMENTS:Aluminum, oxygen

COMPOUND TYPE:Inorganic base

STATE:Solid


MELTING POINT:Not applicable; loseswater on heating to

become aluminumoxide (Al2O3)


SOLUBILITY:Insoluble in water;

soluble in strongacids and bases

Aluminum Hydroxide

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OVERVIEW

Aluminum hydroxide (uh-LOO-min-um hi-DROK-side) isalso known as alumina hydrate, aluminum hydrate, aluminumtrihydrate, hydrated alumina, hydrated aluminum oxide, andaluminum white. It is a white crystalline powder that occursin nature as the mineral gibbsite, one of the three minerals(along with boehmite, diaspore) that makes up bauxite. Baux-ite is a rocky material from which the metal aluminum isextracted commercially. Aluminum hydroxide is perhaps bestknown to the average person as an ingredient in antacids,compounds for the treatment of upset stomach, acid indiges-tion, and related symptoms. It is found in products such asMaalox�, Mylanta�, and Gelusil�. A closely related chemicalcompound, aluminum hydroxychloride (Al2Cl(OH)5) is theactive ingredient in most deodorants and anti-perspirants.

HOW IT IS MADE

Most aluminum hydroxide is produced by treating baux-ite with a hot, concentrated solution of sodium hydroxide

OH OH

OH

Al


(NaOH). As the solution cools, aluminum hydroxide settlesout of the reaction mixture as a gelatinous (jelly-like) precipi-tate, which can then be dried and saved as a white powder. Thealuminum hydroxide can also be precipitated by passingcarbon dioxide gas through the solution.


Aluminum hydroxide is an effective antacid because it is,chemically, a base. As such, it reacts with stomach acid(hydrochloric acid; HCl), to reduce the symptoms of heart-burn, upset stomach, acid indigestion, and gastritis, aninflammation of the stomach lining. The compound can alsobe used to treat peptic ulcers on a long-term basis. A pepticulcer is an open sore in the lining of the stomach or the firstpart of the small intestine.

Aluminum hydroxide also has a number of industrialapplications, such as:

• A raw material for the preparation of other aluminumcompounds;

• An additive for cosmetics, paper, plastics, and rubber togive the final product more bulk;

Aluminum hydroxide. Redatoms are oxygen; white atoms

are hydrogen; and turquoiseatom is aluminum. P U B L I S H E R S



ALUMINUM HYDROXIDE

• In abrasives designed for use with plastics and brass;

• An additive for glass products that adds strength andresistance to attack by chemicals and weathering and toheat shock;

• As the world’s most popular flame retardant.

Studies have not shown that aluminum hydroxide poseshealth risks of any kind to human beings.


‘‘Aluminum Hydroxide.’’ Chemical Land 21.http://www.chemicalland21.com/industrialchem/inorganic/aloh3.htm (accessed on September 18, 2005).

‘‘Aluminum Hydroxide.’’ Drugs.com.http://www.drugs.com/MTM/aluminum_hydroxide.html(accessed on September 18, 2005).

Interesting Facts

Aluminum hydroxide is one ofthe most common adjuvantsused in vaccines today. Anadjuvant is a substance addedto a vaccine to increase theefficiency with which it

prevents disease. The mechanisms by which adjuvants suchas aluminum hydroxide achievethis objective are not alwaysknown.

Words to Know

ADJUVANT A substance added to a vaccineto increase the efficiency with which itprevents disease.

ANTACID A medicine used for the treatmentof upset stomach, acid indigestion, andrelated symptoms.

PRECIPITATE A solid material that settlesout of a solution, often as the result of achemical reaction.


ALUMINUM HYDROXIDE

‘‘Aluminum Hydroxide Resources.’’ [email protected]://names.mongabay.com/drugs/ingredients/ALUMINUM_HYDROXIDE.html (accessed on September 18,2005).

Malakoff, David. ‘‘Public Health: Aluminum Is Put on Trial as aVaccine Booster.’’ Science (May 26, 2000): 1323.

See Also Aluminum oxide


ALUMINUM HYDROXIDE

OTHER NAMES:Alumina

FORMULA:Al2O3

ELEMENTS:Aluminum, oxygen

COMPOUND TYPE:Metallic oxide

STATE:Solid




SOLUBILITY:Insoluble in water and

most organic sol-vents; slowly soluble

in basic solutions.

Aluminum Oxide

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OVERVIEW

Aluminum oxide (uh-LOO-min-um OK-side) is white crystal-line powder that occurs in nature in a variety of minerals,including boehmite, bayerite, corundum, diaspore, and gibb-site. Corundum is second hardest naturally occurring mineral.Only diamond is harder. Aluminum oxide occurs in a variety ofchemical forms in a variety of gemstones, including chryso-beryl, ruby, sapphire, and spinel. The color of these gemstonesis a result of impurities, such as chromium (in the case of ruby)and iron and titanium (in the case of sapphire). The colors mayalso vary depending on the kind and amount of each impurity.

Aluminum oxide’s commercial uses depend not only on itshardness, but also on its high melting point and its low elec-trical conductivity. The compound is also non-combustible andresistant to attack by most solvents and other chemical agents.

HOW IT IS MADE

Aluminum oxide is produced by washing the rocky mate-rial bauxite with a hot solution of sodium hydroxide (NaOH).

Al AlO O O


The aluminum hydroxide (Al(OH3)) that is produced in thisreaction is then heated to drive off water, producing alumi-num oxide. Wastes from coal mining operation are also treatedto extract the aluminum sulfate (Al2(SO4)3) they contain. Thealuminum sulfate is converted to aluminum hydroxidewhich, again, is heated to produce aluminum oxide.


The primary use of aluminum oxide is the manufactureof aluminum metal. When an electric current is passedthrough molten (melted) aluminum oxide, the compoundbreaks down to form aluminum metal and oxygen gas. Themethod is called the Hall process after the American chemistCharles Martin Hall who invented it.

Aluminum oxide is also widely used as an abrasive. Anabrasive is a very hard material used to grind, polish, sand,scour, scrub, smooth or polish some other material. Amongthe products that include aluminum oxide as an abrasive areemery boards, sandpaper, grinding and polishing wheels andbelts, lens grinding devices, and gem polishing wheels.

The high melting point of aluminum oxide also makes ita good refractory product. A refractory material is one thatdoes not melt easily, making it suitable for lining the inside

Aluminum oxide. Turquoiseatoms are aluminum and

orange atoms are oxygen. Graysticks indicate double bonds.



ALUMINUM OXIDE

of furnaces or the manufacture of glass and ceramic materi-als that will not melt when exposed to very high tempera-tures. Some other uses of aluminum oxide include:

• In finely-divided form, as the packing material in chro-matographic columns. Chromatography is a process bywhich individual components of a mixture are sepa-rated from each other by passing them through a tubefilled with some absorbent material (such as aluminumoxide).

• As a catalyst in many industrial chemical reactions;

• In the paper-making process, as a filler that adds bodyto the final product;

• For the production of artificial gemstones;

• As a food additives, where it acts as a dispersant, asubstance that keeps a product from clumping togetherin a package; and

• As the internal coating on frosted light bulbs.

The U.S. Occupational Safety and Health Administration(OSHA) classifies aluminum oxide as a nuisance dust in theworkplace. A nuisance dust is one for which no seriousharmful effects have been identified as long as its releaseis kept under control. It may, however, cause unpleasant

Interesting Facts

• The hardness of materialsis measured on the Mohsscale, named after theGerman mineralogistFrederick Mohs (1773–1839),who suggested the system.The scale runs from 1 (thesoftest known naturalmaterial, talc) to 10 (thehardest known naturalmaterial, diamond).Corundum has a hardnessof 8.8 on the Mohs scale.

• The invention of a methodfor making aluminummetal from aluminumoxide by the 23-year-oldAmerican chemist CharlesMartin Hall (1863–1914)in 1886 resulted in areduction in the priceof aluminum metal fromabout twelve dollars apound to less than a dollara pound.


ALUMINUM OXIDE

symptoms, such as irritation of the skin, eyes, and lungs ifpresent in unusually large amounts. The simplest treatmentfor problems related to nuisance dusts is to move away fromthe contaminated area where an adequate supply of fresh airis available.


‘‘Aluminum Oxide, Al2O3.’’ Accuratus.http://www.accuratus.com/alumox.html (accessed on September19, 2005).

Frost, Randall. ‘‘Abrasives.’’ Gale Encyclopedia of Science. Editedby K. Lee Lerner and Brenda Wilmoth Lerner. 3rd ed. Vol. 1.Detroit, Mich.: Gale, 2004.

‘‘The Mineral Corundum.’’ Amethyst Galleries.http://mineral.galleries.com/minerals/oxides/corundum/corundum.htm (accessed on September 19, 2005).

Misra, Chanakya. Industrial Alumina Chemicals. Washington,D.C.: American Chemical Society, 1986.

See Also Aluminum hydroxide

Words to Know

CATALYST A material that increases the rateof a chemical reaction without undergoingany change in its own chemical structure

CHROMATOGRAPHY A process by whicha mixture of substances passes througha column consisting of some material thatcauses the individual components in themixture to separate from each other.

DISPERSANT A substance that keepsanother substance from clumpingtogether or becoming lumpy.

REFRACTORY Does not melt easily; able towithstand high temperatures.

SOLVENT A substance that is able to dissolveone or more other substances.


ALUMINUM OXIDE


FORMULA:KAl(SO4)2

ELEMENTS:Potassium, aluminum,

sulfur, oxygen


STATE:Solid


MELTING POINT:92.5�C (198�F; loseswater of hydration

beginning at 64.5�C(148�F)

BOILING POINT:200�C (392�F; loses all

water of hydration)

SOLUBILITY:Soluble in cold water;

very soluble in hotwater; insoluble in

alcohol, ether,acetone, and other

organic solvents

AluminumPotassiumSulfate

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OVERVIEW

Aluminum potassium sulfate (uh-LOO-min-um po-TASS-see-um sul-fate) is also known as aluminum potassium sulfatedodecahydrate, potash alum, potassium alum, and kalinite. Itnormally occurs in the form of the dodecahydrate, meaningthat each molecule of the compound is associated withtwelve molecules of water. The formula of the hydrate isKAl(SO4)2�12H2O. In this form, it occurs as white odorlesscrystals. The compound gradually loses its water of hydrationwhen heated, giving up the first nine molecules of water at64.5�C (148�F), and the remaining three molecules of water atabout 200�C (392�F).

Aluminum potassium sulfate belongs to a family of com-pounds known collectively as the alums. The term alum

refers to a double salt that consists of aluminum, the sulfategroup (SO4), and one other metal. The presence of two metals,aluminum plus one other metal, accounts for the name dou-ble salt. Other common alums are aluminum ammoniumsulfate and aluminum sodium sulfate.

S

OO

OO-

S

O

O O

-O

K+ Al3+

O-


The alums were known as far back as ancient Egyptand China, where they were used as deodorants. Alums areeffective for this purpose because they are astringents, sub-stances that cause tissues to shrink or contract, thus redu-cing the tendency of sweat glands to produce perspiration.As astringents, alums were also used in the field of medicineto treat wounds and prevent bleeding. Until the nineteenthcentury, however, chemists did not recognize that the sub-stance they knew as alum was actually a variety of differentcompounds.

HOW IT IS MADE

Aluminum potassium sulfate occurs naturally in the formof the minerals alunite and kalinite. Where these mineralsare available, the compound can be mined and purified toobtain potash alum. Where the minerals are not available,the compound can be produced synthetically by combiningaqueous aluminum sulfate with aqueous potassium sulfate.The two compounds react with each other in solution to formthe double salt, aluminum potassium sulfate, which can thenbe extracted by allowing the solutions to evaporate, duringwhich the desired compound crystallizes out.

Aluminum potassium sulfate.

Red atoms are oxygen; yellowatoms are sulfur; turquoise

atom is potassium; and orangeatom is aluminum. Gray sticks

indicate double bonds.P U B L I S H E R S R E S O U R C E G R O U P


ALUMINUM POTASSIUM SULFATE


One of aluminum potassium sulfate’s major uses is inthe dyeing of fibers and fabrics, where it is employed as amordant. A mordant is a substance that reacts with a dye,helping it attach more permanently to a fiber or fabric.Aluminum potassium sulfate has also been used in thepaper-making industry for many centuries, where it has avariety of applications. For example, it can be used to givepaper a tough, shiny surface or to increase the intensity ofinks, paints, and dyes used on the paper. Some water treat-ment plants also use aluminum potassium sulfate in theirpurification systems. The compound is added to water, whereit combines with colloidal particles suspended in water toform larger clumps, which then settle out of the water. Otheruses of aluminum potassium sulfate include:

• As a food additive, used to control the acidity of theproduct;

• In the manufacture of matches;

• For the waterproofing of fabrics;

• In the tanning of leather;

• In the manufacture of deodorants;

• To add hardness and toughness to cement;

• In the production of fireworks;

Interesting Facts

• During the fifteenthcentury, the Vaticanachieved control of thealum industry in Europe.When King Henry VIII ofEngland quarreled withPope Clemens VII acentury later over hisdesire to marry a

second time, the pope cutoff supplies of alum toGreat Britain. Since alumwas an essential product inthe dyeing of clothes, theEnglish clothing industryrapidly fell into direcircumstances.



• As an astringent in medical treatments; and

• In the preparation of other compounds of aluminum inthe chemical industry.


‘‘Aluminum Potassium Sulfate Resources.’’http://names.mongabay.com/drugs/ingredients/ALUMINUM_POTASSIUM_SULFATE.html (accessed on September 18, 2005).

Hart Davis, Adam. ‘‘Thomas Challoner and His Astonishing AlumIndustry.’’ ExNet.http://www2.exnet.com/1995/12/18/science/science.html#LINKS BACK(accessed on September 18, 2005).

‘‘Material Safety Data Sheet: Aluminum Potassium Sulfate Dodecahydrate.’’ Department of Chemistry, Iowa State University.http://avogadro.chem.iastate.edu/MSDS/AlKSO4.htm(accessed on September 18, 2005).

‘‘Potassium Aluminum Sulfate.’’ Gale Encyclopedia of Science.Edited by K. Lee Lerner and Brenda Wilmoth Lerner. 3rd ed.Vol. 5. Detroit, Mich.: Gale, 2004.

See Also Potassium Sulfate

Words to Know

AQUEOUS SOLUTION A solution that consistsof some material dissolved in water.

ASTRINGENT A material triggers a loss ofwater from tissue, thereby causing thetissues to shrink and contract.

COLLOID A mixture consisting of tiny particlessuspended, but not dissolved, in water.

DOUBLE SALT A salt that includes aluminumand one other metal, such as potassium.

MORDANT A substance that reacts with adye so that it attaches to a fiber or fabricmore easily.



OTHER NAMES:None

FORMULA:NH3

ELEMENTS:Nitrogen, hydrogen


STATE:Gas




SOLUBILITY:Very soluble in cold

water; soluble inalcohol, ether, and

many organic solvents

Ammonia

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OVERVIEW

Ammonia (uh-MOH-nyah) is a colorless gas with a strong,suffocating odor. It was present in the primordial (original)atmosphere of the Earth. Scientists believe that it may havebeen the source of nitrogen for the earliest forms of life.Ammonia was the first chemical compound to be foundin interstellar space, the space between stars. It is a majorcomponent of the atmosphere of many planets in our solarsystem.

Early chemists learned to produce ammonia from animalparts, such as the horns of deer. But it was the Englishchemist and physicist Joseph Priestley (1733–1804) who firstcollected and studied the pure gas. In 1785, the French che-mist Claude-Louis Berthollet (1748–1822) determined the cor-rect chemical formula for the gas, NH3.

In 2004, American companies produced 10,762,000metric tons (11,863,000 short tons) of ammonia, making itthe tenth highest-volume chemical made in the UnitedStates. Only ten years earlier, it had ranked number 5 on

N

H

HH


the list of all chemicals produced by volume. About 90 percentof all the ammonia used in the United States goes to theproduction of fertilizers.

HOW IT IS MADE

Ammonia is produced naturally by the action of certaintypes of bacteria on nitrogen found in the atmosphere. It isalso formed during the decay of dead organisms.

Until the end of the nineteenth century, ammonia wasproduced commercially by the cyanamide process. Calciumcarbide (CaC2), nitrogen gas (N2), and steam were reactedwith each other to produce ammonia.

In the early 1900s, the German chemist Fritz Haber(1868–1934) developed a method for making ammoniadirectly from its elements, nitrogen and hydrogen. The twogases are combined with each other at high temperature(400�C to 650�C; 750�F to 1200�F) and pressure (200 to 400atmospheres; 3,000 to 6,000 pounds per square inch) over acatalyst made of finely-divided iron. Haber’s process was laterrefined and improved by German chemical engineer CarlBosch (1874–1940). Haber and Bosch both won Nobel Prizesin chemistry for their work on the production of ammonia.The Haber-Bosch process remains the most common form ofammonia production in many countries, including the United

Ammonia. Blue atom isnitrogen and white atoms are

hydrogen. P U B L I S H E R S


AMMONIA


States. Small amounts of ammonia are also produced duringthe process by which soft coal is converted to coke.

Ammonia is a natural product of metabolism in all ani-mals. When proteins break down, the nitrogen they containis converted, in part, to ammonia. The ammonia is thenconverted to urea, which is excreted in the urine.


Ammonia is used in a variety of forms as a fertilizer. Itcan be liquified or dissolved in water and sprayed on land, or itcan be converted into any one of a number of compounds, suchas ammonium nitrate, ammonium phosphate, or ammoniumsulfate. In these forms, it is spread as dry granules on the land.Urea, made from ammonia and carbon dioxide, is also used asa feed supplement for cattle. Plants and animals use the

Interesting Facts

• Ammonia’s name comesfrom an ancient Egyptianpractice conducted atthe temple of the sungod Amon (or Ammon)near Karnak. Cameldung burned at thetemple gave off a strongodor (ammonia) and leftbehind a whitecrystalline substanceon the ground. Thewhite substance wasgiven the name ofsal ammoniac, or saltof Amon, and thegas itself laterbecame known asammonia.

• The Haber-Boschprocess was developedlargely because ofGermany’s need forexplosives in World War I.Ammonia gas isconverted to nitric acid,which, in turn, is used inmaking sodium andpotassium nitrate, majorcomponents of explosives.Fritz Haber believed that itwas his patriotic duty tocontribute to the Germanwar effort in whatever wayhe could, which led to hisdevelopment of a newmethod for makingammonia.


AMMONIA

nitrogen in ammonia and its compounds to synthesize newproteins that contribute to their growth and development.

The next largest use of ammonia is in the synthesis ofnitric acid (HNO3). In a process developed by the Germanchemist Wilhelm Ostwald (1853–1932), ammonia, oxygen, andwater are reacted together in a series of steps that resultsin the formation of nitric acid. Nitric acid, the thirteenth mostimportant chemical in the United States in terms of produc-tions, has a number of important uses, including the manu-facture of explosives. Like the Haber-Bosch process, the Ost-wald process contributed to the success experienced byGermany during World War I.

In addition to its use in the manufacture of fertilizersand explosives, smaller amounts of ammonia are used:

• As a refrigerant;

• In the manufacture of plastics;

• As a raw material in the manufacture of other nitrogen-containing chemicals;

• In the production of dyes;

• As a rocket fuel;

• For the neutralization of acids during the refining ofpetroleum;

• In order to produce specialized types of steel; and

• As a nutrient in yeast cultures in food processing opera-tions.

Both gaseous and liquid ammonia pose moderatehealth hazards to those who come into contact withthem. For example, farmers who handle liquid ammoniarisk the possibility of painful blistering of the skin ordamage to the mucous membranes if they come intocontact with the ferilizer. Ammonia fumes can irritatethe mouth, nose, and throat, causing coughing and gag-ging responses. Higher levels of exposure may irritatethe lungs, resulting in shortness of breath and producingheadaches, nausea, and vomiting. Very high exposurescan cause a buildup of fluid in the lungs that can resultin death. Since ammonia is a common ingredient of manyhousehold products, everyone should be aware of itshealth risks, although the threat posed by such productsis, in fact, very small.

AMMONIA



‘‘Ammonia.’’ Masterliness.http://www.masterliness.com/a/Ammonia.htm(accessed on September 19, 2005).

Buechel, K. H., et al. Industrial Inorganic Chemistry. New York:VCH, 2000, pp. 29 43.

‘‘The Facts about Ammonia.’’ New York State Department of Health.http://www.health.state.ny.us/nysdoh/bt/chemical_terrorism/docs/ammonia_general.pdf(accessed on September 19, 2005).

‘‘Toxicological Profile for Ammonia.’’ Agency for Toxic Substancesand Disease Registry.http://www.atsdr.cdc.gov/toxprofiles/tp126.html(accessed on September 19, 2005).

‘‘Uses and Production of Ammonia (Haber Process).’’ Ausetute.http://www.ausetute.com.au/haberpro.html(accessed on September 19, 2005).

See Also Ammonium Chloride; Ammonium Hydroxide;Ammonium Nitrate; Ammonium Sulfate; Nitric Acid;Potassium Nitrate; Urea

Words to Know


METABOLISM The process including all ofthe chemical reactions that occur in cellsby which fats, carbohydrates, and othercompounds are broken down to produceenergy and the compounds needed tobuild new cells and tissues.

MUCOUS MEMBRANES Tissues that linethe moist inner lining of the digestive,respiratory, urinary and reproductivesystems.



AMMONIA

OTHER NAMES:Ammonium muriate;

sal ammoniac;salmiac

FORMULA:NH4Cl

ELEMENTS:Nitrogen, hydrogen,

chlorine


STATE:Solid


MELTING POINT:340�C (640�F;

sublimes at meltingpoint)


SOLUBILITY:Soluble in water;

slightly soluble inalcohol; insoluble in

most organic solvents

Ammonium Chloride

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OVERVIEW

Ammonium chloride (uh-MOH-ni-um KLOR-ide) occursas odorless white crystals with a cool, salt-like taste.The compound is of interest to historians of chemistryas being one of the first chemicals mentioned by ancientscholars and the first compound of ammonia to have beendiscovered. For example, the Roman philosopher Plinythe Elder (23–79 CE) wrote about a substance he calledhammoniacus sal that appears to have been ammoniumchloride. The problem is that various authorities used theterm sal ammoniac for a variety of materials that wereclearly different from each other. No one really knew thecompound’s actual chemical composition until 1700, whenit was discovered by the French botanist Joseph Tournefort(1656-1708). In any case, sal ammoniac was an important rawmaterial in early industrial operations, including primarilydyeing and metallurgical operations.

Sal ammoniac is also the name of the mineral form ofammonium chloride. The mineral occurs only rarely in

HCl-

H

HH

N

+


nature, and only then in arid (dry) regions. Since ammoniumchloride is quite soluble in water, it remains on the groundonly in places where there is little rain. One such location isaround the vents of active volcanoes. The compound isformed in these regions when hydrogen chloride (HCl) involcanic gases and ammonia (NH3) produced by the decayof plants and animals react with each other to form ammo-nium chloride, which then settles out onto the ground.

HOW IT IS MADE

One straightforward method of making ammoniumchloride is by combining an aqueous solution of somecompound of ammonia, usually ammonium sulfate([NH4]2SO4), with hydrochloric acid (HCl) and collectingthe ammonium chloride that forms by evaporation. Com-mercially, the compound is obtained as a by-product of theso-called ammonia-soda process for making sodium carbo-nate (Na2SO4). In this process, invented by the Belgianchemist Ernest Solvay (1838–1922) in 1861, ammonia,sodium chloride (NaCl), and carbon dioxide (CO2) are com-bined with each other in a series of reactions to make

Ammonium chloride. Whiteatoms are hydrogen; blue atomis nitrogen; and yellow atom is

chlorine. P U B L I S H E R S


AMMONIUM CHLORIDE


sodium carbonate, a very important commercial product.Ammonium chloride is also formed during the reactionsand is removed as a by-product.


Ammonium chloride has a wide variety of commercialuses. One of the best known uses is in dry cell batteries. Drycell batteries consist of three parts: the anode (the metalbottom of the battery), the cathode (the metal knob at thetop of the battery), and the electrolyte (a moist solid materialthat makes up the body of the battery). Electrons produced ina chemical reaction within the battery flow out of the cath-ode, through an external circuit (the device to which thebattery is attached), back into the battery through the anode,and back to the cathode through the electrolyte. The electro-lyte in a dry cell battery consists of a pasty mixture ofammonium chloride with water.

Some other uses of ammonium chloride include:

• As a mordant in dyeing and printing operations;

• As a flux for soldering;

• For the production of other ammonium compounds,especially those used as fertilizers;

• In the manufacture of certain types of polymers, espe-cially the family known as the urea-formaldehyde resins;

Interesting Facts

• Sal ammoniac was animportant substance in thestudy of alchemy. The goalsand methods of alchemychanged considerably overthe period from about thetwelfth century to aboutthe sixteenth century andwere somewhat different

from culture to culture. Forexample, one Islamic alche-mist, Abu Bakr Mohammedar-Razi (865–925) classifiedsal ammoniac as one of thefundamental spirits ofmatter, along with mercury,sulfur, and arsenic.


AMMONIUM CHLORIDE

• For the electroplating of metals; and

• As an additive to a licorice-type candy popular in someparts of the world, to which it gives a characteristicsalty taste.

Exposure to ammonium chloride may carry certainhealth risks. When inhaled or deposited on the skin, it maycause irritation of the tissues that may require treatment.The compound is potentially toxic if swallowed. These poten-tial problems are generally of concern primarily to peoplewho work with the compound directly, as in the industriesmentioned above. Anyone who is exposed to ammoniumchloride should see medical attention immediately.


‘‘Ammonium Chloride: Helping to Provide Portable Electricity.’’The Science Center.http://www.science education.org/classroom_activities/chlorine_compound/ammonium_chloride.html(accessed on September 19, 2005).

‘‘Ammonium Chloride, Technical.’’ Zaclon Incorporated.http://www.zaclon.com/pdf/amchltec_datasheet.pdf(accessed on September 19, 2005).

Words to Know


AQUEOUS SOLUTION A solution thatconsists of some material dissolved inwater.

ELECTROPLATING Process by which a thinlayer of one metal is deposited on top ofa second metal by passing an electriccurrent through a solution of the firstmetal.

FLUX A material that lowers the meltingpoint of another substance or mixture ofsubstances or that is used in cleaninga metal.

MORDANT A substance used in dyeing andprinting that reacts chemically with botha dye and the material being dyed to helphold the dye permanently to the material.


AMMONIUM CHLORIDE


‘‘Material Safety Data Sheet: Ammonium Chloride.’’ Department ofChemistry, Iowa State University.http://avogadro.chem.iastate.edu/MSDS/NH4Cl.htm(accessed on September 19, 2005).

Patnaik, Praydot. Handbook of Inorganic Chemicals. New York:McGraw Hill, 2003.

See Also Ammonia; Ammonium Hydroxide; SodiumCarbonate; Urea


AMMONIUM CHLORIDE

OTHER NAMES:Ammonia solution,

aqua ammonia,ammonium hydrate,spirits of hartshorn

FORMULA:NH4OH


oxygen


STATE:Aqueous solution

(exists only insolution)


MELTING POINT:Not applicable


SOLUBILITY:Not applicable

Ammonium Hydroxide

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OVERVIEW

Ammonium hydroxide (uh-MOH-ni-um hye-DROK-side)is a clear, colorless aqueous solution consisting of ammoniagas dissolved in water. The compound does not exist in anyother state. Ammonium hydroxide has a strong pungent,suffocating odor caused by the release of ammonia gas fromthe solution. Most solutions of ammonium hydroxide rangein concentration from less than one percent to about 35 percentammonia. For most commercial purposes the lowest concen-tration is about 10 percent ammonia in water.

HOW IT IS MADE

Ammonium hydroxide is prepared by passing ammoniagas (NH3) into water. Once prepared, ammonium hydroxidesolutions tend to be very stable.


The uses of ammonium hydroxide are closely related tothose of ammonia gas from which it is made. The advantage

H

H

OH–

H HN

+


of using ammonium hydroxide over ammonia is that thereactant (the ammonia) may be more easily controlled whendissolved in water than when available as a gas.

Some uses of ammonium hydroxide include:

• As a cleaning agent in a variety of industrial and com-mercial products, such as household ammonia, wherethe concentration of the solution is generally in therange of 3 to 10 percent;

• In the manufacture of rayon and other textiles;


• As a food additive to maintain the proper level of acid-ity in the food;

• In the production of soaps and detergents, pharmaceu-ticals, ceramics, explosives, and inks; and

• In the fireproofing of wood.

Health hazards posed by ammonium hydroxide are aconsequence of the ammonia present in the solution. Whenexposed to the air, such solutions tend to release someammonia gas, which users may breathe in. The gas may then

Ammonium hydroxide. Whiteatoms are hydrogen; red atom

is oxygen; and blue atom isnitrogen. P U B L I S H E R S



AMMONIUM HYDROXIDE

cause irritation of the eyes, nose, and throat that, for weaksolutions, is generally unpleasant but not dangerous. Expo-sure to higher concentrations of ammonia released fromammonium hydroxide may result in more serious healthproblems, such as severe burning of the eyes, nose, and throatand permanent damage to these parts of the body, includingblindness, lung disease, and death. One of the most danger-ous hazards posed by ammonium hydroxide occurs when it ismixed with substances containing chlorine, such as bleach-ing products. That combination may result in large amountsof heat and toxic gases that can cause serious injuries andeven death.


‘‘Ammonia: Public Health Statement.’’ Agency for Toxic Substancesand Disease Registry.http://www.atsdr.cdc.gov/toxprofiles/tp126 c1.pdf (accessed onSeptember 19, 2005).

‘‘Ammonium Hydroxide.’’ Industrial Resources Group, Ltd.http://www.indresgroup.com/aqua.htm (accessed on September19, 2005).

‘‘Ammonium Hydroxide.’’ Medline Plus Medical Encyclopedia.http://www.nlm.nih.gov/medlineplus/ency/article/002491.htm (accessed on September 19, 2005).

See Also Ammonia

Words to Know

AQUEOUS SOLUTION A solution thatconsists of some material dissolvedin water.

PUNGENT Intensely sharp or biting.


AMMONIUM HYDROXIDE

OTHER NAMES:German saltpeter;Norway saltpeter;

nitric acid,ammonium salt

FORMULA:NH4NO3


oxygen


STATE:Solid



BOILING POINT:211�C (412�F);

decomposes at itsboiling point

SOLUBILITY:Very soluble in water,soluble in alcohol and

acetone

Ammonium Nitrate

KE

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OVERVIEW

Ammonium nitrate (uh-MOH-ni-um NYE-trate) is a whitecrystalline substance first made artificially in 1659 by theGerman chemist Johann Rudolf Glauber (1604–1670). Thecompound does not occur in nature because it is so solublethat it is washed out of the soil by rain and surface water.Ammonium nitrate is stable at lower temperatures, but tendsto decompose explosively when heated to temperatures above200�C (390�F). Its two most important uses today arein fertilizers and explosives. In 2004, it ranked fourteenthamong all chemicals manufactured in the United States. Justover six million metric tons (6.6 million short tons) of thecompound were produced in 2004.

HOW IT IS MADE

Ammonium nitrate is made commercially by passingammonia gas (NH3) and a water solution of nitric acid(HNO3) through a pipe. The ammonia combines with the

HHH

N N

O

O O

H

+ -


nitric acid to form ammonium nitrate. The formula for thisreaction can be written as NH3 + HNO3 ! NH4NO3.

Large amounts of heat are released during the reaction, sothe pipe and supporting equipment must be very strong. Thesolution of ammonium nitrate in water is allowed to evapo-rate, leaving behind pure white crystals of the compound.


The primary use of ammonium nitrate is the manufac-ture of fertilizers. In 2005, about 2 million metric tons(2.2 million short tons) of ammonium nitrate fertilizer wasused in the United States. The compound is added to soil toprovide the nitrogen that plants need to grow. It may be usedby itself or in combination with another nitrogen-rich com-pound, urea, in a mixture known as UAN.

Ammonium nitrate is also an important component ofsome explosives. It provides the oxygen needed to causesome other material to catch fire and burn very rapidly,

Ammonium nitrate. Redatoms are oxygen; white atomsare hydrogen; and blue atoms

are nitrogen. P U B L I S H E R S



AMMONIUM NITRATE

producing an explosion. One common type of explosive ismade of ammonium nitrate mixed with fuel oil and calledANFO (Ammonium Nitrate Fuel Oil). When the mixtureis heated, ammonium nitrate breaks down to release oxy-gen, which causes the rapid combustion (explosion) of thefuel oil.

Some other uses of ammonium nitrate include the following:

• In fireworks, where it provides the oxygen needed toignite other chemicals;

• In the manufacture of nitrous oxide (N2O), commonlyknown as laughing gas;

• In rocket engines, where it provides oxygen needed toburn the rocket fuel;

Interesting Facts

• Glauber named thecompound he discoveredin 1659 nitrum flammans,

Latin for ‘‘flaming nitre.’’He chose the namebecause of the compound’stendency to explode whenexposed to heat.

• An ammonium nitrateexplosion in Texas City,Texas, on April 16, 1947,was responsible for theworst industrial accidentin U.S. history. While beingloaded into two ships atthe Texas City harbor,more than 7.5 millionkilograms (17 millionpounds) of the ammoniumnitrate was exposed toflames and exploded. The

force of the explosionwas so great that it couldbe felt more than 400kilometers (250 miles) awayin Louisiana. Officialsestimate the death tollat 581 people, with morethan 5,000 more injured.

• Two American men,Timothy McVeigh andTerry Nichols, used atruckload of ammoniumnitrate and other materialsto blow up the Alfred P.Murrah Federal Building inOklahoma City, Oklahoma,on April 19, 1995. The eventwas one of the worstterrorist incidents everon American soil.


AMMONIUM NITRATE

• In the manufacture of safety matches, where the com-pound supplies oxygen to substances that catch firewhen the match is struck; and

• As a nutrient in commercial processing for growingyeasts and antibiotics.


‘‘Chemical Profile for Ammonium Nitrate.’’ Scorecard: The Pollution Information Site.http://www.scorecard.org/chemical profiles/summary.tcl?edf_substance_id=6484 52 2. (accessed on September 13, 2005).

Gorman, Christine. ‘‘The Bomb Lurking in the Garden Shed.’’ Time

(May 1, 1995): 54.

Olafson, Steve. ‘‘The Explosion: 50 Years Later Texas City Remembers.’’ The Houston Chronicle (April 14, 1997): A1. Also availableonline athttp://www.chron.com/content/chronicle/metropolitan/txcity/main.html. (accessed on September 13, 2005).

See Also Ammonia, Nitric Acid, Nitrous Oxide


AMMONIUM NITRATE

OTHER NAMES:Diammonium sulfate;

sulfuric acid,diammonium salt

FORMULA:(NH4)2SO4


sulfur, oxygen


STATE:Solid


MELTING POINT:Not applicable;

decomposes above235�C (455�F)



insoluble in alcohol,acetone, and other

common organicsolvents

Ammonium Sulfate

KE

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OVERVIEW

Ammonium sulfate (uh-MOH-ni-um SUL-fate) is an odor-less, colorless to white crystalline solid that occurs in natureas the mineral mascagnite. In 2004, 2.6 million metric tons(2.9 million short tons) of the compound were produced inthe United States, placing it in 21st place among chemicalsmade in that year. More than 95 percent of the ammoniumsulfate produced is used in the production of fertilizers.

HOW IT IS MADE

The primary method of preparation for ammonium sul-fate is the direction reaction between ammonia gas (NH3) andsulfuric acid (H2SO4). The ammonium sulfate produced in thereaction is recovered as white crystals after evaporation ofthe water present in the reaction mixture. Other methods ofpreparation are also used. For example, gypsum (CaSO4�2H2O)can be treated with ammonia (NH3) and carbon dioxide (CO2)to generate ammonium sulfate.

N

H H+

H H

N

H H

H H

S

O O

O O

+2–



Ammonium sulfate is used as a fertilizer because it sup-plies nitrogen and sulfur, two nutrients that plants need to

grow properly. Lesser quantities of the compound are utilizedin water treatment plants where it is used to control the

acidity of the water being processed. Among other uses ofammonium sulfate are:

Ammonium sulfate. Red atomsare oxygen; white atoms are

hydrogen; blue atoms arenitrogen; yellow atom is sulfur.

Gray stick indicates doublebond. P U B L I S H E R S R E S O U R C E

G R O U P


AMMONIUM SULFATE

• In the tanning of leather;

• As a fireproofing agent for fabrics and paper;

• In the manufacture of viscose rayon;

• As an additive to cattle feed

• As a nutrient in bacterial cultures;

• In the processing of certain metals, such as chromiumand gold; and

• In the manufacture of polymers used in the productionof chipboard.


‘‘Ammonium Sulfate.’’ Hazardous Substances Data Bank.http://toxnet.nlm.nih.gov/cgi bin/sis/search/r?dbs+hsdb:@term+@na+Ammonium+Sulfate (accessed on September 20, 2005).

Interesting Facts

The German alchemistAndreas Libau (c.1540 1616),better known by hisLatinized name of Libavius,wrote what is widelyregarded as the firsttextbook on chemistry in

1597. In that book, Alchemia,he described a method formaking ammonium sulfate,probably the first mentionof the compound in modernsources.

Words to Know

ALCHEMY Ancient field of study fromwhich the modern science of chemistryevolved.



AMMONIUM SULFATE

‘‘Ammonium Sulfate Advantage: FAQs.’’ Honeywell.http://www.sulfn.com/main/pages/faqs.asp (accessed on July22, 2005).

‘‘Ammonium Sulfate Industrial Grade.’’ BASF.http://www.basf.de/en/produkte/chemikalien/anorganika/ammonium/ammoniumsulfat_industrial.htm?id=V00 YYuHV7Ro7bsf1Gb (accessed on September 20, 2005).

Bariyanga, Joseph. ‘‘Fertilizer.’’ Chemistry: Foundations and Appli

cations. Edited by J. J. Lagowski. Vol. 2. New York: MacmillanReference USA, 2004.

See Also Ammonia; Sulfuric Acid

AMMONIUM SULFATE



FORMULA:C16H19N3O5S

ELEMENTS:Carbon, hydrogen,nitrogen, oxygen,

sulfur


(pharmaceutical)

STATE:Solid


MELTING POINT:No data available

BOILING POINT:No data available

SOLUBILITY:Soluble in water andalcohol; insoluble in


Amoxicillin

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OVERVIEW

Amoxicillin (uh-MOX-uh-sill-in) is also known asD-(-)-alpha-amino-p-hydroxybenzyl penicillin and (2S,5R,6R)-6-[(R)-(-)-2-amino-2-(phydroxyphenyl)acetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid. Itis an off-white crystalline antibiotic, a substance that inhi-bits the growth of microorganisms. It is generally availablein the form of the trihydrate (having three molecules ofwater for each molecule of amoxicillin) with the formulaC16H19N3O5S�3H2O. Amoxicillin is effective against a numberof disease-causing bacteria, including streptococci, the bac-terium that cause strep throat, and most strains of pneumo

cocci, the bacterium that cause pneumonia, gonococci, thebacterium that cause gonorrhea, and meningococci, the bac-terium that cause meningitis. Amoxicillin works by block-ing the formation of bacteria cell walls. Without cell walls,the bacteria die.

Amoxicillin belongs to a group of semisyntheticallyproduced antibiotics called the aminopenicillins. The term

HH

HH

H

HH

O

O

O

OHO

H

H

H

H

N

N

N

H

SC

C

C CC C

C

CC

C

C

CC

CCH3

CH3


semisynthetic means that some stages in the preparation ofthe compound make use of naturally-occurring organisms,such as bacteria or yeast, and some stages involve chemicalsynthesis. Preparation of the aminopenicillins begins withthe antibiotic penicillin itself, usually made by one of themolds in the Penicillium family, such as Penicillium chryso-genum or Penicillium notatum. The penicillin molecule isthen modified by the addition of a hydroxyl, methyl, or someother group. Other semisynthetic antibiotics related to amox-icillin and penicillin are ampicillin, benzylpenicillin (penicil-lin G), and phenoxymethylpenicillin (penicillin V).

Scottish bacteriologist Alexander Fleming (1881–1955)discovered penicillin in 1928. The antibiotic was first producedfor human use in the early 1940s. Over time, researchers

Amoxicillin. Red atoms areoxygen; white atoms

are hydrogen; black atoms arecarbon; blue atoms are

nitrogen; and green atomis sulfur. Gray sticks are double

bonds; striped sticks show abenzene ring. P U B L I S H E R S



AMOXICILLIN

discovered ways of changing the chemical structure of peni-cillin to create semisynthetic versions. The new antibioticsthey created were more effective than penicillin against awider range of bacteria, often with fewer side-effects. Amox-icillin was discovered by researchers at the Beecham pharma-ceutical laboratories in 1962 and marketed about a decadelater under the trade name of Amoxil�. The drug is nowavailable under a number of trade names, includingLarotid�, Trimox�, Wymox�, Polymox�, and Augmentin�.

HOW IT IS MADE

The preparation of amoxicillin involves a complex seriesof reactions that begins with penicillin produced by molds orother microorganisms. A variety of chemical reagents is thenused to replace one hydrogen atom in the penicillin moleculeby the CH(NH2)C6H4OH group that converts penicillin intoamoxicillin.


Amoxicillin is available only by prescription and is usedagainst a variety of disease-causing bacteria, such as thecocci bacteria listed above, as well as Bordetella pertussis,the bacterium that causes whooping cough, Salmonella typhi,the bacterium that causes typhoid, and Vibrio cholerae, thebacterium that causes cholera.

The safety of amoxicillin has been extensively tested intrials with both experimental animals and humans. It posesno risk to the vast majority of people. As with all drugs,

Interesting Facts

• The original U.S. patent onamoxicillin granted toBeecham Laboratories in1965 has expired, allowingother pharmaceuticalmanufacturers to make the

drug. This fact accountsfor the more than threedozen trade names underwhich it is sold.


AMOXICILLIN

however, some individuals may experience adverse reactionsto the use of amoxicillin. These reactions include fever, skinrash, joint pain, or swollen glands. More serious reactions caninclude nausea, diarrhea, or anaphylaxis, a potentially fatalallergic reaction. Adverse reactions are most likely to occuramong people who have asthma, kidney disease, leukemia,intestinal problems, chronic illness, or a known allergy toother penicillin drugs.


‘‘Amoxicillin.’’ Drugs.com.http://www.drugs.com/amoxicillin.html (accessed on September 20, 2005).

‘‘Amoxicilin.’’ Medline Plus.http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a685001.html (accessed on December 6, 2005).

‘‘Amoxicillin.’’ University of Maryland Medical Center.http://www.umm.edu/altmed/ConsDrugs/Amoxicillincd.html(accessed on September 20, 2005).

‘‘Amoxil� Prescribing Information.’’ GlaxoSmithKline.http://us.gsk.com/products/assets/us_amoxil.pdf (accessed onSeptember 20, 2005).

See Also Penicillin

Words to Know

ANAPHYLAXIS A serious allegic reaction to asubstance that may include respiratorysymptoms, fainting, swelling and itching.

REAGENT A substance used in a chemicalreaction.

SEMISYNTHETIC A compound that isprepared in such a way that some stages in

the preparation use naturally-occurringorganisms, such as bacteria or yeast, andsome stages involve chemical synthesis.



AMOXICILLIN

OTHER NAMES:Pentyl acetate; acetic

acid, amyl ester

FORMULA:CH3COOC5H11


oxygen

COMPOUND TYPE:Ester (organic)

STATE:Liquid


MELTING POINT:�70.8�C (�95.4�F)





Amyl Acetate

KE

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OVERVIEW

Amyl acetate (A-mil AS-uh-tate) is a colorless liquid witha distinctive banana-like flavor and odor. Three major iso-mers of amyl acetate exist: normal (n-amyl), secondary (sec-amyl), and isoamyl (3-methyl-1-butyl) acetate. Isomers are twoor more forms of a chemical compound with the same mole-cular formula, but different structural formulas and differentchemical and physical properties. As an example, the boilingpoints of the three isomers of amyl acetate are 149.2�C(300.6�F), 142.0�C (287.6�F), and 140.0�C (284.0�F), respec-tively. Although the amyl acetates are probably best knownas flavoring agents because of their distinctive banana-likeflavor, they all have a number of interesting industrial appli-cations also.

HOW IT IS MADE

The amyl acetates are made industrially in essentially thesame way they are made in a high school or college chemistry

H3C CH2

CH2 CH3CH2

C

O

OCH2


laboratory. Acetic acid (HC2H3O2) is added to amyl alcohol(C5H11OH) with a small amount of concentrated sulfuric acid(H2SO4) as a catalyst. The specific amyl acetate produceddepends on the specific amyl alcohol used in the reaction.The product is separated from the reaction mixture by boil-ing the liquid mixture.


Amyl acetate is used as a flavoring agent in the UnitedStates and several other countries. It is often blended withother esters to produce flavors that are more fruity androunded. The compound is also used to flavor products suchas chewing gum.

Some applications of amyl acetate depend on its distinc-tive banana-like odor. The compound may be used, for example,to cover up the unpleasant odors present in certain products,

Amyl acetate. Red atoms areoxygen; black atoms are carbon;and white atoms are hydrogen.Gray stick indicates a double

bond. P U B L I S H E R S R E S O U R C E

G R O U P


AMYL ACETATE

such as shoe polish. Amyl acetate is also used as a warningodor in devices through which gases flow, such as respira-tors. A warning odor is a distinctive smell that allows usersto be aware that a leak exists in a product carrying a gas thathas no odor of its own.

Among the many industrial applications of amyl acetateare the following:

• As a solvent for paints and lacquers;

• As an ingredient in fingernail polishes;

• In the production of penicillin; and

• In the manufacture of photographic film, printed anddyed fabrics, and phosphors used in fluorescent lamps.

Amyl acetate is thought to pose a moderate to low healthrisk. It may cause respiratory problems if inhaled or damageto the skin and eyes if spilled on the body. The most serioussafety risk it poses is its flammability. It catches fire easilyand burns rapidly, with a moderate risk of exploding undercertain circumstances.


‘‘Amyl Acetate.’’ CAMEO: Conservation and Art Material Encyclopedia Online.http://www.mfa.org/_cameo/frontend/material_description.asp?name=amyl+acetate&language;=1 (accessed on September21, 2005).

‘‘n amyl acetate.’’ CHEMINFO.http://intox.org/databank/documents/chemical/amylacet/cie455.htm (accessed on September 20, 2005).

‘‘n amyl acetate.’’ New Jersey Department of Health and SeniorServices.http://www.state.nj.us/health/eoh/rtkweb/1321.pdf (accessedon September 21, 2005).

Interesting Facts

Amyl acetate is the primarycomponent of banana oil andpear oil.


AMYL ACETATE

‘‘sec amyl acetate.’’ CHEMINFO.http://intox.org/databank/documents/chemical/amylacet/cie468.htm (accessed on September 20, 2005).

‘‘sec amyl acetate.’’ New Jersey Department of Health and SeniorServices.http://www.state.nj.us/health/eoh/rtkweb/1643.pdf (accessedon September 21, 2005).

See Also Acetic Acid; Cellulose Nitrate; Penicillin

Words to Know

CATALYST A material that increases therate of a chemical reaction withoutundergoing any change in its ownchemical structure

ESTER An organic compound formed in thereaction between an organic acid and analcohol.

ISOMER Two or more forms of a chemicalcompounds with the same molecularformula, but different structural formulasand different chemical and physicalproperties

PHOSPHOR A chemical that gives off lightwhen exposed to an electrical current.


AMYL ACETATE

OTHER NAMES:Pentyl nitrite

FORMULA:C5H11NO2 or

(CH3)2CHCH2CH2NO2


nitrogen, oxygen


STATE:Liquid


MELTING POINT:Not available

BOILING POINT:n-amyl nitrite: 104.5�C

(220�F); isoamylnitrite: 99.2�C (210�F)

SOLUBILITY:Almost insoluble in

water; soluble inalcohol

Amyl Nitrite

KE

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AC

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OVERVIEW

Amyl nitrite (A-mil NYE-trite) commonly occurs in twoisomeric forms: n-amyl nitrite and isoamyl nitrite (3-methy-lamyl nitrite or 3-methylpentyl nitrite). In common usage,the term amyl nitrite most commonly refers to the isoamylform. Both isomers occur as yellowish liquids with a distinc-tive sweet odor and a pungent taste. They are unstable andbreak down when exposed to air, light, or water. Both iso-mers are probably best known as vasodilators, substancesthat cause blood vessels to relax and expand, allowing anincreased flow of blood through the body. Because of itswidespread use as a hazardous recreational drug, isoamylnitrite has been banned, except for specified medical uses.

HOW IT IS MADE

Isoamyl nitrite is prepared in a straightforward synthesisin the reaction between isoamyl alcohol (CH3)2CHCH2CH2OH)and nitrous acid (HNO2). The usual method of preparation is

H3C C

H

H

C

H

H

H

H

H

H

C C N OO


to combine starch with concentrated nitric acid (HNO3) toform gaseous nitrous acid. The nitrous acid is then passedthrough warm isoamyl alcohol. The compound can also beproduced by distilling a mixture of potassium nitrite (KNO2),isoamyl alcohol, and sulfuric acid (H2SO4).


The amyl nitrites are used in medicine for the treatmentof pain due to angina, chest pain that occurs because of theconstriction of blood vessels. The compounds cause the bloodvessels to relax, expand, and ease the flow of blood, with aresulting decrease in chest pain. They are also used by emer-gency medical providers to treat poisoning by hydrogencyanide and hydrogen sulfide gas. The amyl nitrites areconverted in the body to a compound called methemoglobin,which binds to hydrogen cyanide and hydrogen sulfide, redu-cing their toxic effects.

U.S. law permits the sale of amyl nitrites as additives toperfumes and for other odorizing purposes. For example,they may be sold as room deodorizers, to eliminate the

Amyl nitrite. Red atomsare oxygen; black atoms are

carbon; white atoms arehydrogen; and the blueatom is nitrogen. Graysticks indicate double

bonds. P U B L I S H E R S



AMYL NITRITE

unpleasant smells that may accumulate in a space. Somepeople who purchase these room deodorizers or perfumesactually use them as recreational drugs.

An important industrial application of the amyl nitritesis in the production of diazonium compounds. Diazoniumcompounds contain a characteristic -N=N- grouping and con-stitute an important family of dyes.

The health risks associated with the use of the amylnitrites arise because they act as vasodilators. As blood ves-sels expand and blood flow increases after inhalation of amylnitrites, blood rushes to the head, and a person may becomedizzy and light-headed. These symptoms may provide a ‘‘rush’’

Interesting Facts

• Although isoamyl nitritehas legitimate industrialand medical uses, it isprobably best known as arecreational drug called‘‘poppers.’’ The name comesfrom a popping sound thatoccurs when a bottle ofthe liquid is opened. Thehealth consequences ofusing poppers are such

that the U.S. governmentpassed a ban on the sale ofpoppers in 1991, except forcertain specific purposes.The ban has not eliminatedthe use of isoamyl nitriteas a recreational drug,since people can still buythe compound for one ofits permitted uses.

Words to Know

DISTILLATION A process of separating two ormore substances by boiling the mixture ofwhich they are composed and condensing thevapors produced at different temperatures.

ISOMERS Two or more forms of a chemicalcompound with the same molecular formula,

but different structural formulas anddifferent chemical and physical properties.

VASODILATOR Drug that causes bloodvessels to relax and expand.


AMYL NITRITE

of excitement that makes them desirable to some people asstimulants. But prolonged use may result in more serioushealth problems, including headache, nausea, loss of balance,shortness of breath, and rapid heartbeat. For individualswith heart problems, such conditions can lead to heart fail-ure and death.


‘‘Amyl Nitrite.’’ WholeHealthMD.com.http://www.wholehealthmd.com/refshelf/drugs_view/1,1524,35,00.html (accessed on December 7, 2005).

‘‘Amyl Nitrite (Systemic).’’ Medline Plus.http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202034.html (accessed on December 7, 2005).

Gahlinger, Paul M. Illegal Drugs: A Complete Guide to Their His

tory. Salt Lake City, UT: Sagebrush Press, 2001.

‘‘Isoamyl nitrite.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/icsc/icsc/eics1012.htm(accessed on December 7, 2005).


AMYL NITRITE

OTHER NAMES:L-ascorbic acid;

vitamin C

FORMULA:C6H8O6


oxygen


STATE:Solid


MELTING POINT:191�C (376�F);

decomposes


SOLUBILITY:Soluble in water andalcohol; insoluble inether, benzene, and

chloroform

Ascorbic Acid

KE

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AC

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OVERVIEW

Ascorbic acid (as-KOR-bik AS-id), or vitamin C, is one ofthe most important dietary vitamins for humans because itplays a crucial role in building collagen, the protein thatserves as a support structure for the body. It is a water-soluble vitamin, which means that the body excretes anyexcess vitamin C in the urine and cannot store a surplus.For that reason, humans must consume vitamin C in theirdaily diets. Vitamin C is found in many fruits and vegetablesand most kinds of fresh meat. Citrus fruits, such as orangesand lemons, are especially rich in the compound.

Humans have known about the consequences of vitamin Cdeficiency for centuries. People traveling long distanceson land or by sea often came down with an illness calledscurvy. The same illness struck people living in their ownhomes during long winters. The disease was characterized bypain and weakness in the joints, fatigue, bleeding gums,tooth loss, slow healing of wounds, and bruising. These symp-toms were caused as the body’s connective tissue broke down

HOOH

OH

OH

C

C

C

C

C C

H

H

H H

OO


and small blood vessels ruptured. These symptoms began todisappear as fresh foods became more available. If they didnot get enough fresh food in their diets, people could die ofscurvy.

Scurvy was common enough that many people searchedfor its cause and cure. Sailors were especially vulnerable to

Ascorbic acid. Red atomsare oxygen; white atoms arehydrogen; and black atomsare carbon. Gray sticks aredouble bonds. P U B L I S H E R S



ASCORBIC ACID

the disease, and the first recorded investigations involvingvitamin C were done by seafaring men. In 1536, Frenchexplorer Jacques Cartier (1491–1557) cured his sailors ofscurvy by following the advice of Indians in Newfoundland,feeding them extract of pine needles. Scottish physicianJames Lind (1716–1794) began investigating the disease in1747. He read many historical accounts of the diseases andcombined that information with his own observations todeduce that scurvy occurred only among people with verylimited diets. He went on a ten-week sea voyage and fed thesolders various foods to see which ones were best at curingscurvy. Citrus fruits proved to be most effective in prevent-ing the disease, a result that Lind reported in 1753. CaptainJames Cook (1728–1779) led expeditions to the South Seas inthe late 1700s and kept his crew healthy by feeding themsauerkraut. In 1795 the British navy began serving its sailorsa daily portion of lime juice, and two things happened: Britishsailors stopped getting scurvy, and people began callingsailors ‘‘limeys.’’

Many people refused to believe that scurvy was caused bya dietary deficiency, suggesting that it was instead the resultof eating bad food or lack of exercise. In 1907, Norwegianbiochemists Alex Holst (1861–1931) and Theodore Frohlichconducted a study in which guinea pigs were fed an experi-mental diet that caused them to develop scurvy. The linkbetween the vitamin and the disease was firmly establishedby this research. Ascorbic acid was first isolated indepen-dently by the Hungarian-American biochemist Albert Szent-Gyorgi (1893–1986) and the American biochemist CharlesGlen King (1896–1988) in 1932. It was synthesized a yearlater by the English chemist Sir Walter Norman Haworth(1883–1950) and the Polish-Swiss chemist Tadeusz Reichstein(1897–1996), again working independently of each other.

HOW IT IS MADE

Plants and most animals (humans and guinea pigs beingtwo exceptions) synthesize vitamin C in their cells through aseries of reactions in which the sugar galactose is eventuallyconverted to ascorbic acid. For many years, the compound hasbeen made commercially by a process known as the Reichsteinprocess, named after its inventor Tadeusz Reichstein. Thisprocess begins with ordinary glucose, which is converted toanother sugar, sorbitol, which is then fermented to obtain


ASCORBIC ACID

yet another sugar, sorbose. The sorbose is then convertedstep-by-step into a series of other products, the last of whichis ascorbic acid.

Chemists have long been searching for an alternative tothe Reichstein process because it uses so much energy andproduces by-products that are hazardous to the environ-ment. In the 1960s, Chinese scientists developed a methodthat involves only two steps in the synthesis of ascorbicacid, and in the early 2000s, Scottish scientists wereattempting to develop a method that involved only a singlestep using fermentation. Currently, however, the Reichsteinprocess remains the most popular method for making thecompound.


The best known use of vitamin C is as a nutritionalsupplement, taken to ensure that one receives his or herdaily minimum requirement of the vitamin. The recom-mended daily allowance (RDA) of vitamin C for adults is 60milligrams per day. Anyone who eats a well-balanced dietthat includes citrus fruits, tomatoes, and green leafy vegeta-bles probably does not need to take a vitamin supplement.However, the amount of vitamin C one normally receivesfrom a supplement is unlikely to cause any harm.

Interesting Facts

• The vitamin C produced byplants and by syntheticmethods are chemicallyidentical and have identi-cal effects in the humanbody.

• American chemist LinusPauling (1901–1994) believedthat very large doses ofvitamin C could prevent andcure the common cold and

other flu-like diseases.Because of his reputation(he won two Nobel Prizes,one in chemistry, as well asthe Peace Prize), his view-point was highly respected.He was not, however, ableto prove his theory tothe satisfaction of hisscientific colleagues.


ASCORBIC ACID

In addition to its nutritional uses, ascorbic acid has anumber of other industrial applications, including:

• As a food preservative;

• As a reducing agent in chemical processes;

• As a preservative in foods;

• As a color fixing agent in meats, helping meats keeptheir bright red appearance;

• As an additive to bread dough, where it helps increasethe activity of yeast used in the dough; and

• As a treatment for abscission in citrus plants, the ten-dency for a plant to lose its leaves, flowers, and fruits.


‘‘Ascorbic Acid.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/icsc/icsc/eics0379.htm(accessed on September 21, 2005).

Carpenter, Kenneth J. The History of Scurvy and Vitamin C.

Cambridge, UK: Cambridge University Press, 1986.

‘‘L Ascorbic Acid.’’ University of Texas at Austin College of Engineering Department of Biomedical Engineering.http://www.engr.utexas.edu/bme/ugrad/UGLab/resources/MSDS/ascorbic%20acid.pdf (accessed on September 21, 2005).

Mead, Clifford, and Thomas Hager, eds. Linus Pauling: Scientist

and Peacemaker. Portland, OR: Oregon State University Press,2001.

See Also Collagen; Glucose

Words to Know

REDUCTION Chemical reaction in whichoxygen is removed from a substance orelectrons are added to a substance.

SYNTHESIS Chemical reaction in which somedesired chemical product is made fromsimple beginning chemicals, or reactants.


ASCORBIC ACID

OTHER NAMES:Benzol;

cyclohexatriene

FORMULA:C6H6


COMPOUND TYPE:Aromatic hydro-carbon (organic)

STATE:Liquid






acetone

Benzene

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OVERVIEW

Benzene (BEN-zeen) is a clear, colorless liquid with anaromatic (fragrant) odor. It occurs in coal and petroleum,from which it is extracted for commercial use. Benzene isvery flammable, burning with a smoking flame. The com-pound was discovered in 1825 by the English chemist andphysicist Michael Faraday (1791–1867), who gave the com-pound the name of bicarburet of hydrogen. It was given itsmodern name of benzene (benzin, at the time) by the Germanchemist Eilhardt Mitscherlich (1794–1863).

The chemical structure of benzene remained one of thegreat mysteries in chemistry for nearly half a century. Thecompound’s formula, C6H6, suggests that it contains threedouble bonds. A double bond consists of four electrons thathold two atoms in close proximity to each other in a mole-cule. Yet benzene has none of the chemical properties com-mon to double-bonded substances. The solution to this pro-blem was suggested in 1865 by the German chemist FriedrichAugust Kekule (1829–1896). Kekule suggested that the six

H

H H

H H

H

CC

CC C

C


carbon atoms in the benzene molecule are arranged in aring, with one hydrogen atom attached to each carbon. Thering itself consists of three double bonds and three single

bonds, alternating with each other in the ring. The fact that

Benzene. White atoms arehydrogen and black atoms arecarbon. Striped sticks indicatea benzene ring. P U B L I S H E R S



BENZZENE

the double bonds in benzene do not act like double bonds

in other compounds was explained by the German chemistJohannes Thiele (1860–1935), who suggested that the bonds

in benzene shift back and forth between single and doublebonds so rapidly that they are not able to behave like typicaldouble bonds. Chemists now use a variety of chemical for-

mulas for representing the character of chemical bonds inbenzene.

Benzene is a very popular raw material for a variety ofindustrial chemical reactions. In 2004, U.S. manufacturers

produced 8.8 million metric tons (9.7 million short tons) ofbenzene, placing it in twelfth place among all chemicalsmade in the United States that year.

HOW IT IS MADE

At one time, benzene was obtained from coal tar, the

thick gooey liquid left over after soft coal is converted tocoke. This method has now been largely replaced by a varietyof methods that use crude oil or refined petroleum as a raw

material. In the most popular of these methods, toluene(C6H5CH3) from petroleum is heated over a catalyst of plati-

num metal and aluminum oxide (Al2O3). The toluene loses itsmethyl group (-CH3), leaving benzene as the primary product.

Other methods are available for changing the molecularstructure of hydrocarbons found in petroleum and convert-

ing them to benzene.


By far the most important use of benzene is as a raw

material in the synthesis of other organic compounds.More than 90 percent of the benzene produced in the

United States is used to make ethylbenzene (55 percent),cumene (24 percent), and cyclohexane (12 percent). Thefirst two compounds rank fifteenth and twentieth, respec-

tively, among all chemicals produced in the United Stateseach year. Another five percent of benzene production goes

to the synthesis of a large variety of other organic com-pounds, including nitrobenzene, chlorobenzene, and maleic

anhydride, a raw material for the manufacture of plastics.Smaller amounts of benzene are used as a solvent for


BENZZENE

cleaning purposes, in chemical reactions, and as a gasoline

additive.

As with most chemicals, benzene can enter the bodyin one of three ways: through the skin, the nose, or thethroat. People who handle or work with benzene in theirworkplaces are at greatest risk of exposure to benzeneand should take precautions in working with the mate-rial. Because of its serious health hazards, benzene is nolonger included in most materials with which the averageperson comes into contact. On those occasions when aperson does come into contact with benzene, first aidand medical attention should be sought for treatment ofthe exposure.

The health effects of exposure to liquid benzene orbenzene fumes depends on the amount of benzene takeninto the body. The most common symptoms of benzeneexposure include irritation of the mucous membranes, con-vulsions, depression, and restlessness. At greater doses, aperson may experience respiratory failure, followed bydeath. Even at low concentrations, benzene can cause long-term effects for people who are regularly in contact withthe compound. The most important of these effects arecarcinogenic. Benzene is known to cause damage to bonemarrow, resulting in a form of cancer of the blood known asleukemia.

Interesting Facts

• Kekule’s discovery of theformula for benzene is oneof the most interesting inthe history of chemistry.The story is told that heworked so hard on theproblem that he oftendreamed about thecompound at night.One evening, he dreamed

of a snake with a tail in itsmouth. Kekule immediatelyawoke, went to his worktable, and drew a structurefor the benzene moleculeinspired by the snake: amolecule in the shape ofa ring made of carbonatoms.


BENZZENE


‘‘Chronic Toxicity Summary: Benzene.’’ California Office of HealthHazard Assessment.http://www.oehha.org/air/chronic_rels/pdf/71432.pdf(accessed on September 21, 2005).

Newton, David E. ‘‘Benzene.’’ In Gale Encyclopedia of Science.

Edited by K. Lee Lerner and Brenda Wilmoth Lerner. 3rd ed.,vol. 1. Detroit: Gale, 2004.

‘‘Spectrum Chemical Fact Sheet: Benzene.’’ Spectrum Laboratories.http://www.speclab.com/compound/c71432.htm (accessed onSeptember 21, 2005).

‘‘Toxicity Summary for Benzene.’’ The Risk Assessment Information System.http://risk.lsd.ornl.gov/tox/profiles/benzene.shtml (accessedon September 21, 2005).

‘‘Toxicological Profile for Benzene.’’ Agency for Toxic Substancesand Disease Registry.http://www.atsdr.cdc.gov/toxprofiles/tp3.html (accessed onSeptember 21, 2005).

See Also Benzoic Acid; Styrene

Words to Know



MUCOUS MEMBRANES Tissues that line themoist inner lining of the digestive,

respiratory, urinary, and reproductivesystems.



BENZZENE

OTHER NAMES:Carboxybenzene,

benzenecarboxylicacid, phenylformic

acid

FORMULA:C6H5COOH


oxygen


STATE:Solid






acetone

Benzoic Acid

KE

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OVERVIEW

Benzoic acid (ben-ZO-ik AS-id) is the simplest of thearomatic carboxylic acids, a family of organic compoundscontaining the carboxyl (-COOH) group. It occurs in the formof white crystalline needles or thin plates. Many naturallyoccurring plants contain benzoic acid, including most typesof berries and the natural product called gum benzoin, aplant common to the islands of Java, Sumatra, and Borneo.Gum benzoin may contain up to 20 percent benzoic acid.Benzoic acid is also excreted by most animals (except fowl)in the form of a related compound called hippuric acid(C6H5CONHCH2COOH).

HOW IT IS MADE

Some benzoic acid is prepared from gum benzoin andother natural compounds containing high concentrations ofthe compound. Three methods are available for making ben-zoic acid commercially. In one method, toluene (C6H5CH3) is

C

CC C

C C

CHO O

H

H

H

H

H


oxidized at high temperature and pressure over a cobaltcatalyst. In a second procedure, phthalic anhydride(C6H4(CO)2O) is heated to remove carbon dioxide, with theformation of benzoic acid. In the third method, toluene is

Benzoic acid. Red atoms areoxygen; white atoms are hydrogen;

and black atoms are carbon.P U B L I S H E R S R E S O U R C E G R O U P


BENZZOIC ACID

first converted to benzotrichloride (C6H5Cl3), which is thenhydrolyzed to obtain benzoic acid.


More than half of all the benzoic acid produced in theUnited States is used in the manufacture of various poly-

meric products, primarily the family of plastics known as thepolyvinyl acetates (PVAs). The PVAs, in turn, are used asadhesives, caulks, sealants, and coatings for paper, film,

and plastic foil. About a quarter of all benzoic acid is con-verted to its sodium and potassium salts, sodium benzoate

(C6H5COONa) and potassium benzoate (C6H5COOK), for use asfood preservatives. Sodium benzoate and potassium benzoate

are now the most widely used food preservatives in the world.They are added to a host of products, such as soft drinks and

fruit juices, jams and jellies, baked goods, and salad dres-sings. They are also added to a number of non-food productssuch as mouthwashes, toothpastes, cosmetic creams, and

deodorants.

Other uses of benzoic acid include:

• As an additive to antifreezes, where is acts to preventcorrosion of engine parts;

• As a seasoning agent in the processing of tobacco pro-

ducts;

• As a stabilizing agent in the processing of photographs;and

• For the treatment of fungal infections.

Benzoic acid and its sodium and potassium salts pose

moderate health hazards to people who work directly withthem. They may cause skin, nose, and eye problems ifinhaled or deposited on the body. In the form of finely

divided dust, they may also pose a fire or explosive risk.Most people do not encounter any of these compounds in a

form in which they pose a health risk. All three compoundsare considered safe by the U.S. Food and Drug Administra-

tion as food additives provided their concentration in foodsdoes not exceed 0.1 percent. Other nations have set a safe

level for the three compounds as food additives as high as1.25 percent.


BENZZOIC ACID


‘‘Benzoic Acid.’’ Chemical Land 21.http://www.chemicalland21.com/arokorhi/industrialchem/organic/BENZOIC%20ACID.htm (accessed on September 22,2005).

‘‘Benzoic Acid and Sodium Benzoate.’’ International Programme onChemical Safety.http://www.inchem.org/documents/cicads/cicads/cicad26.htm(accessed on September 22, 2005).

‘‘Benzoic Acid (CASRN 65 85 0).’’ U.S. Environmental ProtectionAgency.http://www.epa.gov/iris/subst/0355.htm (accessed on September 22, 2005).

See Also Denatonium Benzoate

Words to Know


HYDROLYSIS The process by which acompound reacts with water to formtwo new compounds.



BENZZOIC ACID

OTHER NAMES:b,b-Carotene;

carotaben

FORMULA:C40H56


COMPOUND TYPE:Hydrocarbon

(organic)

STATE:Solid




SOLUBILITY:Insoluble in water;slightly soluble inalcohol; soluble in

ether, acetone,benzene, and fats

Beta-Carotene

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OVERVIEW

Beta-carotene (b-carotene; BAY-tuh KARE-oh-teen) belongsto a family of organic compounds called the carotenoids. Thecarotenoids are all brightly pigmented (colored) compoundsfound in a number of plants, bacteria, algae, and fungi. Beta-carotene is responsible for the yellowish to orange color ofpumpkins, apricots, sweet potatoes, nectarines, and, most nota-bly, carrots. The compound also occurs in spinach and broccoli,but in such small concentrations that the green chlorophylpresent masks the orange color of beta-carotene. In its pure form,beta-carotene occurs as purple crystals shaped like thin leaflets.

In plants, algae, and photosynthetic bacteria, beta-caro-tene plays an important role in photosynthesis, the processby which plants convert water and carbon dioxide into car-bohydrates and oxygen. In nonphotosynthetic bacteria andfungi, beta-carotene protects the organism against the harm-ful effects of light and oxygen.

Animals require beta-carotene for normal growth anddevelopment, but are unable to manufacture the compound

C

C

C C C C CC

C

C

C

C

CH

H H

H H H H H

H H H H

H

H

HH

H

CH3

CH3 CH3

CH3CH3CH3

C

CH3

CH3 C

CH3CH3

CC

C C CC C C C C CC C C C

H

H


themselves. As a result, they must ingest some beta-carotenefrom plant sources in order to stay healthy. The compound is

a provitamin, a substance that is converted in the body to avitamin. Beta-carotene is converted into vitamin A, whoserole in the body is the maintenance of strong bones and teeth

and healthy skin and hair.

Beta-carotene also acts as an antioxidant, a substance

that attacks free radicals in the body that may cause cancer.It may also protect against heart disease and strengthen the

body’s immune system.

Beta-carotene was first isolated by the German chemistHeinrich Wilhelm Ferdinand Wackenroder (1789–1854), who

extracted the compound from carrot roots in 1831. The com-pound was first synthesized in 1950 by the Swiss chemist

Paul Karrer (1889–1971).

Beta carotene. White atomsare hydrogen and black atoms

are carbon. P U B L I S H E R S



BETA CAROTENE

HOW IT IS MADE

Beta-carotene can be obtained from natural sources bycrushing or pulverizing the source (such as carrots) andadding a solvent that will dissolve the organic componentsof the plant. These components can then be separated fromeach other by chromatographic techniques. A major com-mercial source of beta-carotene obtained by this method isthe algae Dunaliella salina, which grows in large salt lakesin Australia. The compound can also be prepared syntheti-cally by one of two methods, the BASF and the Rochemethods, both named after the pharmaceutical firmswhere they were developed. Both methods of preparationbegin with long-chain hydrocarbons containing abouttwenty carbon atoms each. These hydrocarbons are thenjoined to each other to form the 40-carbon beta-carotenecompound.


Beta-carotene has two uses: in vitamin supplements andas a food additive. Anyone who eats a healthy diet thatincludes foods rich in vitamin A, such as fish oil, liver,eggs, butter, and orange or yellow vegetables and fruits,will get adequate amounts of beta-carotene. However, many

Interesting Facts

• The name carotene comesfrom the Latin word for‘‘carrot.’’

• Scientists have found away to change the geneticstructure of rice so that itcontains beta-carotene.The modified rice isdesigned to help people incountries where vitamin Adeficiency is a seriousproblem.

• At least eight othercarotenoids are known.They include a-carotene,b,c-carotene, andc, c-carotene.


BETA CAROTENE

people take vitamin supplements to ensure that they haveenough beta-carotene (as well as other vitamins) in theirdaily diet. Although some warnings have been issued abouttaking too much vitamin A, there is no clinical evidencethat an overdose of the vitamin does any long-term harm toa person.

Beta-carotene is used as a food additive to increase thecolor intensity of a product. It is used primarily with yellowand orange foods, such as butter and margarine, although itis sometimes added to ice cream and fruit juices as well.Beta-carotene is used in only very small amounts as a foodadditive. In these amounts, it poses no health hazard tohumans or other animals. The compound has also beenused in experiments to test its effectiveness against certaindiseases, such as lung cancer. In such cases, it has beenfound to be more harmful than beneficial, increasing therisk of cancer and death among people participating in thestudies.


‘‘Beta carotene.’’ University of Bristol School of Chemistry.http://www.chm.bris.ac.uk/motm/carotene/beta carotene_home.html (accessed on September 22, 2005).

Words to Know

ANTIOXIDANT A chemical that attacks freeradicals, chemical structures that attackcells and may be responsible for thedevelopment of cancer.

CHROMATOGRAPHY A process by which amixture of substances passes through acolumn consisting of some material thatcauses the individual components in themixture to separate from each other.

FREE RADICAL An atom or group of atomswith a single unpaired electron. Free

radicals are very active chemicallyand tend to attack and destroy othercompounds. They are responsible fordamage in cells that may lead to a numberof health problems, including cancer andageing.



BETA CAROTENE

‘‘Beta carotene.’’ University of Maryland Medical Center.http://www.umm.edu/altmed/ConsSupplements/BetaCarotenecs.html (accessed on September 22, 2005).

Palvetz, Barry A. ‘‘A Bowl of Hope, Bucket of Hype?’’ The Scientist

(April 2, 2001): 15.

‘‘Taking Supplements of the Antioxidant.’’ Consumer Reports (September 2003): 49.

See Also Chlorophyll


BETA CAROTENE

OTHER NAMES:Orthoboric acid;

hydrogenorthoborate;boracic acid

FORMULA:H3BO3

ELEMENTS:Hydrogen, boron,

oxygen

COMPOUND TYPE:Inorganic acid

STATE:Solid



BOILING POINT:Decomposes above

its melting point

SOLUBILITY:Somewhat soluble inwater, ethyl alcohol,

and glycerol

Boric Acid

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OVERVIEW

Boric acid (BORE-ik ASS-id) is a colorless, odorless, whiteor colorless powder or crystalline material with a slightly oilyfeeling that slowly decomposes with heat, changing first tometaboric acid (HBO2), then to pyroboric acid (H2B4O7), andeventually to boric oxide (B2O3). The compound’s solubilityis very much a factor of temperature. In cold water, about5 grams (0.2 ounce) of boric acid dissolve in 100 mL(3.4 ounces) of water, while at 100�C (212�F), its solubilityincreases to 25 grams (0.9 ounce) in 100 mL (3.4 ounces) ofwater.

Boric acid occurs naturally in a number of locationswhere it has precipitated out of hot springs. It may occurthen in the form of the mineral sassolite. Given its abun-dance in nature, it is not surprising that the compound hasbeen known to and used by humans for many centuries. Forexample, the Greeks are known to have used boric acid as anantiseptic, to preserve foods, and as a cleaning agent. Thefirst person to prepare boric acid in Europe is thought to be

BHO OH

OH


the German chemist Wilhelm Homberg (1652–1715), who in1702 treated natural borax (Na2B4O7�10H2O) with acid toobtain a product he called sedative salt, probably a form ofboric acid. The chemical structure of the compound wasdetermined in 1808 by the French researchers Louis-JosephGay-Lussac (1778-1850) and Louis-Jacques Thenard (1777–1857).

HOW IT IS MADE

The most common method of producing boric acid isby treating the relatively abundant borax with hydrochlo-ric or sulfuric acid and crystallizing out the boric acidthat forms in the reaction. A less common method ofpreparation involves the treatment of borax brine solu-tions with a chelating agent that binds to the boratespresent in the brine, which can then be converted toboric acid.

Hydrogen orthoborate. Redatoms are oxygen; white atomsare hydrogen; and yellow atom

is boron. P U B L I S H E R S



BORIC ACID


By far the greatest amount of boric acid is used in theproduction of heat-resistant (borosilicate) glass, glass fibers,porcelain enamels, crockery, laboratory glassware, and otherspecialized types of glass and ceramic materials. In 2004,about 80 percent of all the boric acid used in the UnitedStates was applied to these purposes. Although accountingfor a much smaller amount of boric acid, another well-knownuse of the compound is as an antiseptic in eyewashes, oint-ments, and mouthwashes. It is also used as a preservative infoods and as a fungicide on citrus fruit crops. In the UnitedStates, a residue of no more than 8 parts per million ispermitted on fruits treated with boric acid.

Some other important applications of boric acid includethe following:

• In the production of flame retardant materials;

• As a pesticide for the treatment of cockroaches, blackcarpet beatles, termites, fleas, fire ants, centipedes,grasshoppers, and slugs;

• As a flux in welding and brazing;

• In the synthesis of many boron compounds;

Interesting Facts

• The most common sourcesof boric acid are hotsprings and volcanic sitessuch as the mineralsprings at Vichy andAix-la-Chapelle in Franceand Wiesbaden inGermany, around thevolcanic regions ofTuscany in Italy, and indry lakes of Californiaand Nevada, such asCalifornia’s Borax Lake.

• Boric acid was once usedas an ingredient in talcumand diaper powders and insalves for diaper rashesbecause of its antisepticproperties. The compoundwas eventually banned forsuch uses, however, whenregulators decided that itwas too toxic if it acci-dentally entered the bodythrough an open wound orby being swallowed.


BORIC ACID

• To provide the finishing touches on the production ofleather and fur products;

• In the manufacture of latex paints; and

• In the nickel plating of metallic products.

Boric acid is toxic if swallowed. It causes nausea, vomit-ing, diarrhea, and stomach cramps. In extreme cases, it cancause the collapse of the circulatory system, delirium, con-vulsions, coma, and death. Ingestion of no more than 5 grams(0.2 ounce) of boric acid can cause death in an infant. Inges-tion of 15 to 20 grams (0.5 to 0.7 ounce) by an adult can alsobe fatal. Boric acid can also cause irritation of the skin,which, in extreme cases, can result in a condition known asborism. Borism is characterized by dry skin, eruptions of theskin and mucous membranes, and gastric disturbances.


‘‘Borax; Boric Acid, and Borates.’’ IPM of Alaska.http://www.ipmofalaska.com/files/Borates.html (accessed onOctober 12, 2005).

‘‘Boric Acid: Technical Description.’’ Manufacturas Los Andes.http://www.mandes.com.ar/technic boric acid.php (accessedon October 12, 2005).

Potter, Mike. ‘‘Cockroach Elimination.’’ University of KentuckyEntomology.http://www.uky.edu/Agriculture/Entomology/entfacts/struct/ef614.htm (accessed on October 12, 2005).

Words to Know

BRINE SOLUTION A solution that issaturated with or nearly saturated withsodium chloride or other inorganicsalts.

CHELATING AGENT An organic compoundthat binds (‘‘grabs on to’’) some specific

compound or compounds present in amixture.

FLUX A material that lowers the meltingpoint of another substance or mixture ofsubstances or that is used in cleaning ametal.


BORIC ACID

OTHER NAMES:n-Butane

FORMULA:C4H10


COMPOUND TYPE:Alkane; saturated


STATE:Gas



BOILING POINT:�0.5�C (31�F)


water; soluble inethyl alcohol, ether,

and chloroform

Butane

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OVERVIEW

Butane (BYOO-tane) is a colorless gas with the odor ofnatural gas that is highly flammable and explosive. It existsin two isomeric forms. Isomers are forms of a chemical com-pound with the same molecular formula (in this case, C4H10),but different structural arrangements. In one isomer (‘‘normal’’or ‘‘n- ’ butane), the four carbon atoms are arranged in a con-tinuous chain, while in the other (‘‘iso-butane’’), three carbonatoms are arranged in a continuous chain and the fourthcarbon atom is attached to the middle atom in that chain.

Butane occurs naturally in natural gas, where it is pre-sent to the extent of about 1 percent, and in petroleum,where it exists only in very small amounts. Butane is usedprimarily as a fuel and as a chemical intermediary, a com-pound used to produce other chemical substances.

HOW IT IS MADE

Butane is obtained during the separation of natural gasinto its components. Natural gas consists primarily (70 to

H C

H

H

C

H

H

H

H

H

H

C C H


90 percent) of methane. Other components include ethane(about 9 percent), propane (about 3 percent), and butane(about 1 percent). The remaining 1 to 2 percent of naturalgas is impurities, including nitrogen, carbon dioxide, com-pounds of sulfur, and water. The process of separating naturalgas into its components begins with the removal of water.The natural gas is forced through some drying agent, such asdiethylene glycol (HO(CH2)2O(CH2)2OH), which efficientlyremoves water from the gas. The dry gas is then treated withan agent to remove carbon dioxide, compounds of sulfur, andother impurities. Diethanolamine (HO(CH2)2NH(CH2)2OH) isan efficient ‘‘scavenger’’ of many of these impurities.

After dehydration and removal of impurities, the remaininggas consists almost entirely of simple hydrocarbons, primarilymethane, ethane, propane, and butane. These hydrocarbons canbe separated from each other by cooling them until they reachthe point at which they become liquid. As each componentliquefies, it can be removed from the gas and further purified.For example, butane changes from a gas to a liquid at �0.5�C(31�F) and propane liquefies at about �42�C (�44�F). So as the

Butane. Black atoms arecarbon; white atoms are

hydrogen. All sticks are singlebonds. P U B L I S H E R S R E S O U R C E

G R O U P


BUTANE

hydrocarbon mixture cools, liquid butane can be removed beforeany other components liquefy. In actual practice, liquid butaneand propane are removed together, leaving behind only ethaneand methane. The mixture of liquid butane and propane is knownas liquid petroleum gas (LPG). Since propane and butane havemany similar properties, there is often no commercial reason togo to the expense of separating them from each other. LPG istypically stored above or below ground in large, insulated con-tainers and shipped in insulated trucks or rail cars.


Butane, in both gaseous and liquid form, is widely usedas a fuel. Because it is easily stored and transported in smallcontainers, it is used as a fuel for backpacking stoves, smallspace heaters, and portable torches. Butane is also the fuelmost commonly used in cigarette lighters. It may be used inits pure form or in combination with propane as liquefiedpetroleum gas (LPG). Butane is also used as a fuel for largerhousehold and industrial operations.

In terms of volume, one of the major uses of butane is inthe synthesis of other organic compounds, especially syntheticrubber and high-octane liquid fuels used in aviation. The gas

Interesting Facts

• Some people have usedbutane as a recreationaldrug, inhaling it to get‘‘high.’’ The practice isextremely dangerous,however, and has led someusers to die of asphyxiation(suffocation).

• Researchers at SurreySatellite Technology, Ltd.in the United Kingdomhave built a small satellitethe size of a soccer ball

that is propelled bypressurized butane gas.The butane thruster wasbuilt for $15,000 and waslaunched aboard a RussianCosmos spacecraft in June2000.

• Contact with liquid butaneor LPG can cause frostbite,for which first aid involveswashing with cold water.


BUTANE

is sometimes added to gasoline in cold climates to improvethe rate at which the fuel evaporates and burns. A relativelynew application for butane is as a propellant for sprayproducts, such as hair spray and spray paints, and as arefrigerant. Butane is being used for these purposes as asubstitute for chlorofluorocarbons (CFCs), which have beenshown to have damaging effects on the Earth’s ozone layer.Small amounts of butane are also used as food additives,usually in foods that are dispensed as sprays.

The primary health hazard posed by butane is its narco-tic effects. When inhaled, either accidentally or intention-ally, it produces a sequence of bodily changes that include, atfirst, a sense of euphoria and excitement. Increased dosesmay then produce harmful results, such as nausea, vomiting,sneezing, coughing, blurred vision, slurred speech, andincreased salivation. Even higher doses result in confusion,perceptual distortion, hallucinations, and delusions. Even-tually, a sequence of life-threatening conditions may develop,including depression of the central nervous system, irregularheartbeat, drowsiness, coma, and death.


‘‘Acute Exposure Guideline Levels (AEGLs) for n butane.’’ NationalAdvisory Council, U.S. Environmental Protection Agency.Washington, DC: U.S. Environmental Protection Agency, April2004. Also available online athttp://www.epa.gov/oppt/aegl/pubs/tsd102.pdf (accessed onDecember 29, 2005).

‘‘Butane.’’ International Labour Organization.http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc02/icsc0232.htm (accessed on December 29, 2005).

Words to Know

EUPHORIA A state of extreme happiness andenhanced well-being.

HALLUCINATIONS Visions or otherperceptions of things that are not reallypresent.


BUTANE

‘‘Butane.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/pims/chemical/pim945.htm#SectionTitle:2.1%20%20Main%20risks%20and%20target%20organs (accessed on December 29, 2005).

Russell, Justin. ‘‘Fuel of the Forgotten Deaths.’’ New Scientist

(February 6, 1993): 21 23.

See Also Methane; Propane


BUTANE

OTHER NAMES:Three forms exist;

see Overview

FORMULA:C6H12O2; see Overview

for expandedformulas


oxygen

COMPOUND TYPE:Carboxylic acids

(organic)

STATE:Liquid


MELTING POINT:�98.9�C (�146�F) to�78�C (�108�F)

BOILING POINT:95.1�C (203�F) to126.1�C (259.0�F)

SOLUBILITY:Insoluble or slightly

soluble in water;soluble in alcohol and

ether

Butyl Acetate

KE

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OVERVIEW

Butyl acetate (BYOO-til AS-uh-tate) exists in threeisomeric forms. Isomers are two or more forms of a chemicalcompound with the same molecular formula, but differentstructural formulas and different chemical and physicalproperties. Their names and synonyms are as follows:n-butyl acetate is known as butyl ester, or butyl ethanoate;sec-butyl acetate is called 1-methylpropyl ester and aceticacid sec-butyl ester; and tert-butyl acetate is known by1,1,-dimethylethyl ester or acetic acid, tert-butyl ester. Theexpanded chemical formulas for the forms are slightlydifferent: n-butyl acetate, CH3COOCH2CH2CH2CH3; sec-butyl acetate, CH3COOCH(CH3)(C2H5); and tert-butyl acetate,CH3COOC(CH3)3.

About 100,000 kilograms (250,000 pounds) of then-butyl isomer, the most popular, is produced each year inthe United States. By far the most common use of the com-pound (and the isomers) is as an industrial solvent, withabout 90 percent of total output going for this use.

CH3CO H

H

H

H

H

HOC CH3C C


HOW IT IS MADE

All three isomers of butyl acetate are made by reactingacetic acid (CH3COOH) with the appropriate butyl alcohol(n-butyl alcohol, sec-butyl alcohol, or tert-butyl alcohol,respectively).


The primary use of all three isomers of butyl acetate is asa solvent in the production of lacquers and paints; photo-graphic film; resins; and coatings for furniture, fixtures,containers, and automobiles. Since the 1990s, these com-pounds have been substituted for other solvents that areconsidered hazardous environmental pollutants.

Other uses of the isomers are as follows:

• n-butyl acetate: as an odor enhancer in perfumes; in thesynthesis of synthetics flavors, pharmaceuticals, andother organic compounds;

Butyl acetate. Red atomsare oxygen; white atoms arehydrogen; and black atoms

are carbon. Gray sticks indicatedouble bonds. P U B L I S H E R S



BUTYL ACETATE

• sec-butyl acetate: as a thinner for nail enamels and asolvent for leather finishes;

• tert-butyl acetate: as a gasoline additive.

Relatively little data are available on the health effectsof exposure to the isomers of butyl acetate. The chemical isknown to cause skin rash, respiratory problems, and burningof the eyes upon contact. And by comparing it with othersimilar organic compounds, the assumption is made thatlong-term exposure to high concentrations would result indamage to the nervous system. Since most people do notencounter butyl acetate in the pure form, these risks areminimal. Only workers in one of the fields in which thechemical is used need take special precautions to use carein working with the amyl acetates.

Interesting Facts

• Scientists have discoveredthat the butyl acetates arepresent in the so-calledalarm pheromonessecreted by animals,particularly insects. Analarm pheromone is achemical secreted when

an animal is under attack.It alerts other animals inthe neighborhood to theattack and ‘‘tells’’ them torespond to the attack thathas been detected.

Words to Know

ISOMER One of two or more forms ofa chemical compound with the samemolecular formula, but different structuralformulas and different chemical andphysical properties.

SOLVENT A substance that is able to dissolveone or more other substances


BUTYL ACETATE


‘‘Global Ethyl, Butyl Acetate Demand Expected to Rebound.’’ The

Oil and Gas Journal (April 24, 2000): 27.

‘‘n butyl acetate.’’ New Jersey Department of Health and SeniorServices.http://www.state.nj.us/health/eoh/rtkweb/1329.pdf (accessedon September 22, 2005).

‘‘Occupational Safety and Health Guideline for tert butyl Acetate.’’Occupational Health and Safety Administration.http://www.osha.gov/SLTC/healthguidelines/tertbutylacetate/recognition.html (accessed on September 22, 2005).

‘‘sec butyl acetate.’’ Scorecard: The Pollution Information Site.http://www.scorecard.org/chemical profiles/summary.tcl?edf_substance_id=105%2d46%2d4 (accessed on September 22,2005).


BUTYL ACETATE

OTHER NAMES:Three forms of butylmercaptan exist; see

Overview

FORMULA:C4H10S


sulfur

COMPOUND TYPE:Mercaptan (organic)

STATE:Liquid


MELTING POINT:Forms vary greatly;

see Overview

BOILING POINT:Forms vary; see

Overview

SOLUBILITY:Insoluble or slightly

soluble in water(depending on form);soluble in alcohol and

ether

Butyl Mercaptan

KE

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OVERVIEW

Three isomers of butyl mercaptan (BYOO-til mer-KAP-tan) exist. Isomers are two or more forms of a chemicalcompound with the same molecular formula, but differentstructural formulas and different chemical and physicalproperties. The names and synonyms of the isomers are:n-butyl mercaptan, known as 1-butanethiol, 1-mercapto-butane, or n-butyl thioalcohol; sec-butyl mercaptan, called2-butanethiol or 1-methyl-1-propanethiol; and tert-butyl mer-captan, also known as 2-methyl-2-propanethiol. The isomershave slightly different expanded chemical formulas:n-butyl mercaptan, CH3CH2CH2CH2SH; sec-butyl mercaptan,CH3CH2CH(SH)CH3; and tert-butyl mercaptan, CH3C(CH3)(SH)CH3.The isomers have vastly differing melting points: n-butylmercaptan, �115.67�C (�176.21�F); sec-butyl mercaptan,�165�C (�265�F); and tert-butyl mercaptan, �0.5�C (31�F). Boil-ing points differ, but not as greatly: n-butyl mercaptan,98.46�C (209.2�F); sec-butyl mercaptan, 85�C (180�F); and tert-butyl mercaptan, 64�C (150�F).

CS

H

HC

H

H

C

H

H HH3C


All three isomers of butyl mercaptan are mobile liquids(liquids that flow easily) with very strong skunk-like odors.At one time, chemists thought that the butyl mercaptanswere responsible for the distinctive odor of skunk spray.Research has now shown that some mercaptans are foundin skunk spray, but the butyl mercaptans are not amongthem.

HOW IT IS MADE

A number of methods are available for the productionof the butyl mercaptans. The most common methodinvolves the reaction between an iodobutane (a butanemolecule with one iodine atom, such as CH3CH2CH2CH2I)and a sulfhydryl compound, such as KSH. In this reaction,

Butyl mercaptan. White atomsare hydrogen; black atoms are

carbon; and the turquoise atomis selenium. P U B L I S H E R S



BUTYL MERCAPTAN

the sulfhydryl group (-SH) replaces the iodine to form thebutyl mercaptan.


More than 500,000 kilograms (1 million pounds) of thebutyl mercaptans are produced each year in the United

States. Their primary uses are as solvents and in the prepara-tion of other organic compounds, especially insecticides and

herbicides. Among their other uses are:

• Additives for natural gas, which normally has no odor,so that leaks can be easily detected;

• As an additive to enhance the flavor and aroma ofcertain foods;

• Nutrient in the maintenance of bacterial cultures.

All three isomers of butyl mercaptan are highly toxic.

Anyone exposed to their vapors should seek medical atten-tion immediately. The compounds are also very flammableand must be handled with care to prevent their catching fire.

Since most individuals never come into contact with thebutyl mercaptans, their health and safety risks are of con-

cern primarily to workers who handle them in their everydayjobs.

Interesting Facts

• The Israeli army reportedlydeveloped a ‘‘skunk bomb’’containing mercaptans touse as a crowd-controldevice against Palestinians.

• The Guinness WorldRecords book classifies thebutyl mercaptans as beingamong the two smelliest

compounds in the world.The other chemical is ethylmercaptan.

• The odor of the butylmercaptans is said to bedetectable at a distance ofnearly a kilometer (about ahalf mile) from its source.


BUTYL MERCAPTAN


Bauman, Richard. ‘‘Getting Skunked: Understanding the Anticsbehind the Smell.’’ Backpacker (May 1993): 30 31.

‘‘n Butyl Mercaptan.’’ International Chemical Safety Cards.http://www.cdc.gov/niosh/ipcsneng/neng0018.html (accessedon September 14, 2005).

‘‘The Stink that Stays.’’ Popular Mechanics (December 2004): 26.

Wood, William F. ‘‘Chemistry of Skunk Spray.’’ Humboldt StateUniversity.http://www.humboldt.edu/~wfw2/chemofskunkspray.html(accessed on September 14, 2005).

Words to Know

ISOMER One of two or more forms of achemical compound with the samemolecular formula, but different structuralformulas and different chemical andphysical properties.

MERCAPTAN Organic compound thatcontains a sulfhydryl group (-SH)attached to a carbon.


BUTYL MERCAPTAN

OTHER NAMES:BHA and BHT

FORMULA:BHA: C11H16O2; BHT:

C15H24O


oxygen


STATE:Solid

MOLECULAR WEIGHT:BHA: 180.24 g/mol;BHT: 220.35 g/mol

MELTING POINT:BHA: 51�C (124�F);BHT: 71�C (160�F)

BOILING POINT:BHA: 268�C (514�F);BHT: 265�C (509�F)

SOLUBILITY:Both are insoluble inwater and soluble inethyl alcohol; BHT is

also soluble in acetoneand benzene

Butylated Hydroxy-anisole and ButylatedHydroxytoluene

KE

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OVERVIEW

Butylated hydroxyanisole (BYOO-til-ay-ted hi-DROK-see-ANN-i-sole) and butylated hydroxytoluene (BYOO-til-ay-ted hi-DROK-see-TOL-yoo-een) are very popular food additives used topreserve fats and oils. They both are antioxidants, which arecompounds that prevent oxygen from reacting with sub-stances and changing them into other materials. BHA andBHT prevent the oxidation of fats and oils that would convertthem into rancid, foul-smelling, harmful products.

BHA is a white or pale yellow waxy solid with a faintpleasant odor. BHT is a white crystalline solid. Both compoundsare members of the phenol family of organic compounds. Thephenols are compounds containing a benzene ring of six carbonatoms to which is attached at least one hydroxyl (-OH) group.

HOW IT IS MADE

A variety of methods are available for the preparation ofBHA. The most common method involves the reaction


between p-methoxyphenol (CH3CH2OC6H4OH) and isobutene((CH3)2C=CH2) or tert,-butyl alcohol ((CH3)3COH) over a cata-lyst of silica (silicon dioxide; SiO2) or alumina (aluminumoxide; Al2O3) at temperatures of about 150�C (302�F). BHTis usually made by reacting p-cresol (CH3C6H4OH) with iso-butene.


The most important use of both BHA and BHT is as foodpreservatives. When these compounds are added to productscontaining fats or oils, oxygen reacts with the additive (BHAor BHT) rather than the food itself, protecting the food fromspoiling. Among the vast array of food products containingeither BHA or BHT or both are cereals, seasonings, frostings,dessert mixes, instant potatoes, packaged popcorn, baked goods,pie crusts, meat products, potato chips, candy, sausage, freeze-dried meats, butter, cheese, crackers, bread, vegetable oils,margarine, nuts, beer, and chewing gum.

Both compounds are also added to animal feed as preserva-tives. BHA and BHT are added to a number of non-food products

BHA (left) and BHT (right).

Red atoms are oxygen; whiteatoms are hydrogen; and blackatoms are carbon. Gray sticksindicate double bonds. Stripedsticks indicate a benzene ring.



BUTYLATED HYDROXYANISOLE AND BUTYLATED HYDROXYTOLUENE

as well. These products include paraffin wax, lipstick, eye shadow,lip-gloss, mascara, body and face lotions, diaper rash ointment,deodorant soaps, moisturizers, and shaving gels and creams.

The antioxidant properties of BHA and BHT make themsuitable for other applications also. For example, they aresometimes added to paints and inks to prevent a ‘‘skin’’ fromforming on top of these liquids. The skin is formed when thepaint or ink reacts with oxygen in air to form a solid com-pound. The compounds are also used as additives for thepreservation of drugs, rubber products, petroleum products,the plastics used in food wraps, and the petroleum wax coat-ings used on food boxes.

Questions have been raised about the possible healthbenefits and risks posed by BHA and BHT. On the one hand,these compounds may contribute to good health by destroy-ing substances in the body that can lead to cancer. They mayalso destroy the herpes virus and the human immunodefi-ciency virus (HIV). Most nutritionists agree that antioxi-dants can be helpful in protecting cells and tissues fromaging and damage by oxygen.

On the other hand, BHA and BHT may also be responsiblefor certain health problems. For example, some people appearto be allergic to these compounds, causing skin rashes, hives,or tightness in the chest, although such reactions arethought to be rare. Other people may have problems metabo-lizing BHA and BHT properly, resulting in a build-up of thecompounds in their bodies.

Scientists are uncertain about the possible long-termhealth effects of BHA and BHT. Some studies suggest thatthese compounds may affect liver or kidney function or maybe carcinogenic. Studies on this subject are inconclusive,however, and the U.S. Food and Drug Administration hasdecided that the two compounds can be used as food addi-tives if the amount added is less than 0.02 percent by weight.

As with all chemicals, direct exposure to large dosesof BHA or BHT can cause serious health problems. In oneexperiment, for example, adults who ingested four grams(0.14 ounce) of BHA experienced stomach pain, vomiting,dizziness, confusion, and temporary loss of consciousness.That amount of BHA is tens or hundreds of thousands of timesthe amount one would consume in foods or other products,however. Only people who work directly with the compoundwould ever worry about an effect such as this one.




‘‘Butylated Hydroxyanisole.’’ CHEC’s HealtheHouse.http://www.checnet.org/healthehouse/chemicals/chemicalsdetail2.asp?Main_ID=330 (accessed on January 9, 2006).

‘‘Butylated Hydroxyanisole.’’ Gale Encyclopedia of Science. Editedby K. Lee Lerner and Brenda Wilmoth Lerner. 3rd ed., vol. 1.Detroit: Gale, 2004.

‘‘Butylated Hydroxyanisole.’’ Hazardous Substances Data Bank.http://toxnet.nlm.nih.gov/ (accessed on Jnauary 9, 2006).

‘‘Butylated Hydroxyanisole (BHA; tert butyl 4 hydroxyanisole) andButylated Hydroxytoluene (BHT; 2,6 di tert butyl p cresol).’’ InFood Antioxidants: Technological, Toxicological, and Health

Perspectives, edited by D. L. Madhavi, S. S. Deshpande, andD. K. Salunkhe. New York: Dekker, 1996.

‘‘Butylated Hydroxytoluene.’’ Gale Encyclopedia of Science. Editedby K. Lee Lerner and Brenda Wilmoth Lerner. 3rd ed., vol. 1.Detroit: Gale, 2004.

‘‘Butylated Hydroxytoluene.’’ International Chemical Safety Cards.http://www.cdc.gov/niosh/ipcsneng/neng0841.html (accessedon January 9, 2006).

Words to Know

CARCINOGEN A chemical that causescancer in humans or other animals.



OTHER NAMES:Methyltheobromine;

theine

FORMULA:C8H10N4O2


nitrogen, oxygen

COMPOUND TYPE:Organic base

(alkaloid)

STATE:Solid




begins to sublime atabout 90�C (190�F)

SOLUBILITY:Slightly soluble inwater and alcohol;

soluble in chloroform

Caffeine

KE

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OVERVIEW

Caffeine (kaf-EEN) is an organic base that occurs natu-rally in a number of plant products, including coffee beans,tea leaves, and kola nuts. It occurs as a fleecy white crystal-line material, often in the form of long, silky needles. Itusually exists as the monohydrate, C8H10N4O2�H2O, althoughit gives up its water of hydration readily when exposedto air.

Scientists believe that humans have been drinking bev-erages that contain caffeine for thousands of years. The firstrecorded reference to a caffeine drink can be found in aChinese reference to the consumption of tea by the emperorShen Nung in about 2700 BCE. Coffee is apparently a muchmore recent drink, with the earliest cultivation of the coffeetree dated at about 575 CE in Africa.

Caffeine was first studied scientifically by two Frenchchemists, Joseph Bienaime Caventou (1795–1877) and PierreJoseph Pelletier (1788–1842), who were very interested inthe chemical properties of the alkaloids. Between 1817

H3C

N O

O

N

CC

CH3

CH3

C

N

NH

CC


and 1821, Caventou and Pelletier successfully extractedcaffeine, quinine, strychnine, brucine, chinchonine, andchlorophyll (not an alkaloid) from a variety of plants. Thefirst synthesis of caffeine was accomplished in 1895 by theGerman chemist Emil Hermann Fischer (1852–1919), who wasawarded the 1902 Nobel Prize in chemistry for his work onthe alkaloids.

Caffeine belongs to a class of alkaloids called the methyl-xanthines. Chocolate, from the cocoa tree Theobroma cacao

contains another member of the class, theobromine. Bothcaffeine and theobromine are stimulants, that is, compounds

Caffeine. Red atomsare oxygen; white atoms are

hydrogen; black atomsare carbon; and blue atoms are

nitrogen. Gray sticks aredouble bonds. P U B L I S H E R S


CAFFEINE


that act on the nervous system to produce alertness, excite-ment, and increased physical and mental activity.

HOW IT IS MADE

Caffeine can be extracted from coffee, tea, and kolaplants by one of three methods. These methods are usedprimarily to produce the decaffeinated counterparts of theproducts: decaffeinated coffee, decaffeinated tea, or decaffei-nated soft drinks. A commercial variation of these proceduresis to treat the waste products of tea or coffee processing, suchas the dust and sweepings collected from factories, for theextraction of caffeine.

In the first of the three extraction methods, the naturalproduct (coffee beans, tea leaves, or kola beans) are treatedwith an organic solvent that dissolves the caffeine from theplant material. The solvent is then evaporated leaving behindthe pure caffeine. A second method follows essentially thesame procedure, except that hot water is used as the solventfor the caffeine. A more recent procedure involves the use ofsupercritical carbon dioxide for the extraction process.Supercritical carbon dioxide is a form of the familiar gasthat exists at high temperature and high pressure. It behavesas both a liquid and a gas. Not only is the supercritical carbondioxide procedure an efficient method of extracting caffeine,but it has virtually none of the harmful environmental andhealth problems associated with each of the other two meth-ods of extraction.

Caffeine is also made synthetically by heating a combi-nation of the silver salt of theobromine (C7H8N4O2Ag) withmethyl iodide (CH2I), resulting in the addition of one carbon

Interesting Facts

• Americans drank 6.3billion gallons of coffee,2.4 billion gallons of tea,and 15.3 billion gallons of

caffeinated soft drinks in2003.


CAFFEINE

and two hydrogens to the theobromine molecule and convert-ing it to caffeine.


Caffeine is used in foods and drinks and for medicalpurposes. Its primary action is to stimulate the central ner-vous system. People drink coffee, tea, or cola drinks to stayawake and alert because caffeine creates a feeling of addedenergy. It does this by increasing heart rate, improving bloodflow to the muscles, opening airways to aid breathing, andreleasing stored energy from the liver to provided added fuelfor the body. In large quantities, caffeine can also causenervousness, insomnia, and heart problems. The effects ofcaffeine can linger in the body for more than six hours. Inmedical applications, caffeine is sometimes used as a heartstimulant for patients in shock, to treat apnea (loss of breath-ing) in newborn babies, to counteract depressed breathinglevels as a result of drug overdoses, and as a diuretic.

Caffeine stimulates the brain in two ways. First, becauseit has a chemical structure similar to that of adenosine, itattaches to adenosine receptors in the brain. Adenosine is asubstance that normally attaches to those receptors, slowingbrain activity and causing drowsiness. By blocking thosereceptors, caffeine increases electrical activity in the brain,creating a feeling of alertness. Caffeine also works in thebrain like drugs such as heroin and cocaine, although in amuch milder way. Like those drugs, caffeine increases dopa-mine levels. Dopamine is a chemical present in the brain thatincreases the body’s feeling of pleasure.

Studies have shown that caffeine can become addictive.People who use the compound eventually need to take more

Words to Know

ALKALOIDS Organic bases that contain theelement nitrogen.

DIURETIC A substance that increases theflow of urine.


CAFFEINE


and more of it to get the same effect. When some people try tostop using caffeine, they may suffer from headache, fatigue,and depression, though these symptoms can be controlledby gradually reducing the amount of caffeine consumed.Either way, withdrawal symptoms end after about a week.


‘‘Caffeine.’’ Neuroscience for Kids.http://faculty.washington.edu/chudler/caff.html (accessed onSeptember 23, 2004).

‘‘Caffeine Chemistry.’’ Erowid Vault.http://www.erowid.org/chemicals/caffeine/caffeine_chemistry.shtml (accessed on September 23, 2005).

Cherniske, Stephen. Caffeine Blues: Wake Up to the Hidden Dangers

of America’s #1 Drug. New York: Warner Books, 1998.

Kluger, Jeffrey. ‘‘The Buzz on Caffeine.’’ Time (December 20,2004): 52.

Weinberg, Alan Bennet, and Bonnie K. Bealer. The World of

Caffeine: The Science and Culture of the World’s Most Popular

Drug. New York: Routledge, 2002.

See Also Carbon Dioxide; Theobromine


CAFFEINE

OTHER NAMES:Limestone; chalk;aragonite; calcite

FORMULA:CaCO3

ELEMENTS:Calcium, carbon,

oxygen


STATE:Solid


MELTING POINT:Calcite: 1330�C

(2430�F); aragonite:decomposes at about

825�C (1520�F)


SOLUBILITY:Very slightly soluble

in water; soluble indilute acids; insoluble

in organic solvents

Calcium Carbonate

KE

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AC

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OVERVIEW

Calcium carbonate (KAL-see-um CAR-bun-ate) is one ofthe most common compounds on Earth, making up about7 percent of Earth’s crust. It occurs in a number of mineralsand other natural materials, including aragonite, calcite,chalk, limestone, marble, marl, oyster shells, pearls, and tra-vertine. Stalactites and stalagmites found in caves are madeprimarily of calcium carbonate. As indicated by the meltingpoints of aragonite and calcite, the compound’s physicalproperties may differ somewhat depending on its crystalform. It typically occurs as an odorless, tasteless white pow-der or colorless crystals.

HOW IT IS MADE

Calcium carbonate is so abundant in nature that demandfor the compound can be met by mining natural sources,such as chalk, limestone, and marble quarries. The com-pound can also be produced in the laboratory by reacting

O

O O

Ca

C


calcium chloride (CaCl2) with sodium carbonate (Na2CO3). Thecalcium carbonate formed in this reaction precipitates out of(separates from) the solution and can be recovered by filtration.


One well known use of calcium carbonate is as an antacid,a substance that neutralizes excess stomach acid (hydrochlo-ric acid; HCl) and relieves the symptoms of acid indigestion,heartburn, upset stomach, and sour stomach. Large amountsof the chemical are also used for a variety of industrial uses,including:

• In agriculture, where it is used to maintain properacidity of soil and supply calcium needed by growingplants;

Calcium carbonate. Red atomsare oxygen; black atom is

carbon; white atom is calcium.Gray stick is a double bond.



CALCIUM CARBONATE

• In the paper-making industry, where it is used to make

strong products with a very white color, glossy finish,and firm texture for printing and dyeing;

• As a filler in the manufacture of plastics to reduce thecost of production;

• In the construction industry, where it is used in theproduction of concrete structures, such as paving-stones, tubes, and sewage tanks, in ready-mixed con-crete, and in prefabricated elements;

• In the production of paints and other types of coatingmaterials because of its ability to provide weather resis-tance, protect the coating against corrosion, reducedrying time, and maintain the proper acidity of thecoating material;

• In a variety of environmental applications, such as coun-teracting the increased acidity of lakes and other bodiesof water caused by acid precipitation, treating wastegases to remove sulfur and nitrogen oxides that pollutethe air; and purifying water and waste water; and

• In the manufacture of lime (calcium oxide; CaO) which,itself, has a host of industrial applications.

Interesting Facts

• It is said that Cleopatrashowed her extravagance bydissolving pearls (which aremade of calcium carbonate)in vinegar and drinking theresulting solution.

• Stalagmites and stalactitesform in caves when calciumbicarbonate (CaHCO3)dissolved in groundwaterreaches the top of a caveand gives up carbon dioxide(CO2) to the air. Whencalcium bicarbonate loses

carbon dioxide, it isconverted to calciumcarbonate, which precipi-tates out on the roof ofthe cave as a stalactite.If the calcium bicarbonatedoes not lose carbondioxide until it drips offthe roof and falls on thefloor of the cave, thecalcium carbonate thatis formed builds up astalagmite on the floorof the cave.


CALCIUM CARBONATE


‘‘Calcium Carbonate.’’ National Institute for Occupational Safetyand Health.http://www.cdc.gov/niosh/npg/npgd0090.html (accessed onSeptember 24, 2005).

‘‘Calcium Carbonate Powder.’’ Reade.http://www.reade.com/Products/Minerals_and_Ores/calcium_carbonate.html (accessed on September 24, 2005).

Tegethoff, F. Wolfgana, with Johannes Rohleder and EvelynKroker, eds. Calcium carbonate: From the Cretaceous period

into the 21st century. Boston: Birkhauser Verlag, 2001.

See Also Calcium Oxide

Words to Know

PRECIPITATE A solid material that settlesout of a solution, often as the result of achemical reaction.


CALCIUM CARBONATE

OTHER NAMES:Calcium hydrate;

caustic lime; hydatedlime; slaked lime

FORMULA:Ca(OH)2

ELEMENTS:Calcium, oxygen,

hydrogen


STATE:Solid


MELTING POINT:Not applicable; loses

water when heated tobecome calcium oxide

(CaO)



water; soluble inglycerol

Calcium Hydroxide

KE

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OVERVIEW

Calcium hydroxide (KAL-see-um hye-DROK-side) is a soft,white odorless solid that occurs as granules or a powder. It has aslightly bitter, alkaline taste. Calcium hydroxide absorbs car-bon dioxide readily from the air, changing to calcium carbonate(CaCO3). For this reason, the compound often is contaminatedwith the carbonate unless it is kept in tightly sealed containers.Calcium hydroxide is a relatively inexpensive chemical and, forthat reason, is used in production processes where a base isneeded. Although calcium hydroxide is not very soluble inwater, a suspension of the finely divided powder in water canbe made, a suspension known as limewater or milk of lime.

HOW IT IS MADE

Calcium hydroxide is produced by adding water to cal-cium oxide (CaO). This reaction is highly exothermic andmust be carried out with some care to avoid loss of theproduct through spattering.

Ca++ –O

O–

H

H–



Calcium hydroxide has a number of uses in building andpaving materials. It is found in mortar, plasters, and cements.When used in mortar, calcium hydroxide is mixed with sandand water to make a paste. The paste is put between bricks tohold them together. When water in the paste evaporates, theremaining sand-calcium hydroxide mixture becomes a hard,strong adhesive holding the bricks together.

Calcium hydroxide is also used extensively as a neutraliz-ing agent. As a base, it reacts with acids formed in industrialoperations, in the environment, and in other situations. Forexample, soil that is too acidic for plants to grow properly canbe treated with calcium hydroxide. The hydroxide ion (OH�) inthe calcium hydroxide reacts with the hydrogen ion (H+) inthe acidic soil to form water, resulting in a more neutral soil.

Calcium hydroxide. Red atomsare oxygen; white atoms arehydrogen; and the turquoiseatom is calcium. P U B L I S H E R S



CALCIUM HYDROXIDE

A similar application involves the treatment of exhaust gasesfrom factories with calcium hydroxide. Nitrogen and sulfuroxides in the gases, which are the primary cause of acid rain,are neutralized when passed through ‘‘scrubbers’ containingcalcium hydroxide.

Among the many other uses of calcium hydroxide are:

• In the leather and hide tanning industry, where calciumhydroxide is used to remove hair from hides and then toneutralize tanning solutions;

• For the purification of sugar solutions, such as thoseused in making fruit juices;

• As a component of certain types of pesticides;

• As an additive to lubricants and oil drilling fluids, toimprove the viscosity of the fluids;

• In the manufacture of paints and waterproof coatings;

• As a food additive, used for the purpose of preventingfoods from becoming too acidic;

• As an accelerant (a compound that increases the rate ofa chemical reaction) in processes for the production ofsynthetic rubber and plastics; and

• As a food additive in poultry feed, to improve thestrength of egg shells.

Exposure to calcium hydroxide can cause irritation ofthe skin, eyes, and respiratory system. These conditions aretreated satisfactorily by flushing the contaminated area withample amounts of water. People who work directly withcalcium hydroxide in the workplace are more likely to be atrisk for health problems because of their exposure to larger

Interesting Facts

• One of the oldest methodsof coating a surface is withwhitewash, a mixture madeof calcium hydroxide,water, and chalk (calcium

carbonate). Whitewash isused to whiten the walls ofa building, a fence, orsome other structure.


CALCIUM HYDROXIDE

amounts of the chemical for longer periods of time. In suchcases, more serious health problems, such as burns and blis-tering of the skin, damage to the retina of the eye, and injuryto the gastrointestinal system may develop.


‘‘Calcium Hydroxide or Hydrated Lime.’’ Peters Chemical Company.http://www.peterschemical.com/calcium_hydroxide_or_hydrated_li.htm (accessed on September 26, 2005).

‘‘Material Safety Data Sheet: Calcium Hydroxide Products.’’ Pulpdent Corporation.http://www.pulpdent.com/c_hydro/CHMSDS.pdf (accessed onSeptember 26, 2005).

See Also Calcium Oxide

Words to Know

EXOTHERMIC REACTION A reaction inwhich heat is produced.


CALCIUM HYDROXIDE

OTHER NAMES:Lime; quicklime;burnt lime; calx;

unslaked lime;fluxing lime

FORMULA:CaO

ELEMENTS:Calcium, oxygen


STATE:Solid


MELTING POINT:2,898�C (5,248�F)

BOILING POINT:Not available

SOLUBILITY:Reacts with water

to form calciumhydroxide; soluble in

acids; insoluble inalcohol and mostorganic solvents

Calcium Oxide

KE

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OVERVIEW

Calcium oxide (KAL-see-um OK-side) is an odorless crystal-line or powdery solid that, in a pure form, is white to off-gray. Itoften appears with a yellowish or brownish tint to the presenceof impurities, especially iron. Calcium oxide reacts with waterto form calcium hydroxide (Ca(OH)2) with the evolution ofsignificant amounts of heat. The compound is strongly caustic.

Calcium oxide has been known since ancient times. TheRoman writer Cato the Elder (234–149 BCE) described onemethod of producing the compound in 184 BCE. Another earlyRoman scholar, Pliny the Elder (23–79 CE) discussed the com-pound at length in his book Historia Naturalis (Natural

History), published in 70 CE. By the early fifteenth century,most of Europe was using calcium oxide (widely referred toas lime) in the construction of buildings. The Scottish che-mist Joseph Black (1728–1799) carried out some of the ear-liest scientific studies of calcium oxide. He found that whenthe compound is exposed to air, it combines with carbondioxide to form calcium carbonate.

Ca O


HOW IT IS MADE

The process for making calcium oxide is believed to beone of the first chemical reactions known to humans, datingback to prehistoric times. When limestone (calcium carbo-nate; CaCO3) is heated, carbon dioxide (CO2) is driven off,leaving calcium oxide behind. The reaction was probablydiscovered very early in human history because limestoneis a common, readily available material in the form of chalkand sea shells, and the amount of heat needed to produce thereaction can easily be produced in a simple wood fire. A moreefficient method for carrying out the reaction is to heat thelimestone in a kiln (oven) at temperatures of 500�C to 900�C(900�F to 1,600�F), resulting in a more complete conversionof calcium carbonate to calcium oxide. This method is stillused today for the commercial preparation of calcium oxide.


The most important single use of calcium oxide is in metal-lurgy, particularly in the production of steel. When calciumoxide is added to the furnace in which steel is made, it reactswith sulfur, phosphorus, silica, and other impurities present inthe mixture from which steel is produced. The complex mixturethat results can be poured off the top of the molten steel in theform of a slag, a nonmetallic waste formed during the produc-tion of metals. Calcium oxide plays a comparable role in themanufacture of other metals, such as aluminum and magne-sium. About 40 percent of all the calcium oxide produced in theUnited States goes to metallurgical applications.

The next most important use of calcium oxide is inpollution control devices. Smoke that leaves a factory’s

Calcium oxide. Red atom isoxygen and green atom is

calcium. Gray stick shows adouble bond. P U B L I S H E R S



CALCIUM OXIDE

smokestack, for example, contains oxides of sulfur and nitro-gen that, in the atmosphere, combine with water to formsulfuric acid and nitric acid. To prevent the formation ofthese pollutants, ‘‘scrubbers’’ can be installed in smokestacks.The scrubbers contain some chemical that reacts with andneutralizes the oxides of sulfur and nitrogen. One of themost common compounds used for this purpose is calciumoxide. About 15 percent of all calcium oxide used in theUnited States goes to this application.

Some other uses of calcium oxide include:

• In water treatment plants, to control acidity of thewater being treated and to remove impurities presentin the water;

• In the construction industry, where it is used to makeplaster, mortar, stucco, bricks, and other building materials;

• As a filler to strengthen paper products;

Interesting Facts

• Calcium oxide is oftenused to ‘‘lime’’ lake watersthat have been acidified byacid rain. It reacts with andneutralizes acids in thelake formed when nitricand sulfuric acid in acidrain are carried to earth byrain, snow, sleet, and otherforms of precipitation.

• When calcium oxide isheated near its meltingpoint, it gives off a brilliantwhite light. In the yearsbefore electricity wasavailable for lighting,particularly during thesecond half of thenineteenth century, heatedlime was used to produce

the bright lights neededto illuminate stageproductions. From thispractice came theexpression ‘‘being in thelimelight’’ to refer to anyonewho was in public view oflarge groups of people.

• Because it was thoughtto accelerate the decom-position of soft tissue,quicklime has historicallybeen used in the burial ofdiseased animals andhumans. For example,bodies of plague victimsin London in 1666 weredirected to be buried inquicklime.


CALCIUM OXIDE

• As a refractory, a heat-resistant material used to linethe insides of furnaces;

• In the production of other chemical materials;

• As an additive for poultry feed;

• In insecticides and fungicides;

• In the removal of hair from hides before tanning; and

• As a food additive to maintain proper acidity and givebulk to a food product.

Exposure to calcium oxide can cause damage to the skin,eyes, nose, and respiratory system. People who use the pro-duct in their line of work or at home (for garden purposes,for example) must exercise extreme caution to avoid swallow-ing, breathing in, or otherwise coming into contact with thechemical. If such contact occurs, it should be washed offcompletely and medical assistance requested.


‘‘Calcium Oxide or Quicklime.’’ Peters Chemical Company.http://www.peterschemical.com/calcium_oxide_or_quicklime.htm (accessed on September 27, 2005).

‘‘Chemical of the Week Lime.’’http://scifun.chem.wisc.edu/chemweek/Lime/lime.html(accessed on September 27, 2005).

‘‘Cheminfo.’’ Canadian Centre for Occupational Health and Safety.http://intox.org/databank/documents/chemical/calcoxid/cie11. htm (accessed on September 27, 2005).

‘‘Metallurgy Information Area.’’ National Lime Association.http://www.lime.org/ENV02/Metal802.htm#IS (accessed onSeptember 27, 2005).

See Also Calcium Carbonate; Calcium Hydroxide

Words to Know

CAUSTIC Strongly basic or alkaline materialthat irritates or corrodes living tissue.

METALLURGY The science of working withmetals.


CALCIUM OXIDE

OTHER NAMES:see Overview

FORMULA:see Overview

ELEMENTS:calcium, hydrogen,

phosphorus, oxygen

COMPOUND TYPE:Inorganic salts

STATE:Solid

MOLECULAR WEIGHT:136.06 to 310.20 g/mol

MELTING POINT:see Overview; tribasic

form: 1670�C(3040�F)


SOLUBILITY:See Overview

Calcium Phosphate

KE

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AC

TS

OVERVIEW

The three forms of calcium phosphate (KAL-see-um FOSS-fate) all occur as tasteless, odorless, colorless to white crystallineor powdery solids.

Dibasic calcium phosphate, CaHPO4, is also called cal-cium monohydrogen phosphate, dicalcium orthophosphate,or secondary calcium phosphate. It is usually found in theform of hydrate, such as CaHPO4�2H2O. It does not melt,instead decomposing when heated to 109�C (228�F).

Monobasic calcium phosphate, Ca(H2PO4)2, is also knownas calcium hypophosphite, calcium biphosphate, acid calciumphosphate, monocalcium orthophosphate, and primary cal-cium phosphate. It usually exists in the form of the hydrateCa(H2PO4)2�H2O. It decomposes when heated to 200�C (400�F)

Tribasic calcium phosphate, Ca3(PO4)2, may be called cal-cium orthophosphate, tricalcium orthophosphate, tertiarycalcium orthophosphate, or tricalcium phosphate. Unlike theother two forms, the tribasic form contains no hydrogen atoms.

O O

Ca2+

Ca2+

Ca2+

O

O

P

3–

O O

O

O

P

3–


The dibasic and tribasic forms of calcium phosphate areinsoluble in water and alcohol, but soluble in most acids. Mono-basic calcium phosphate is soluble in water and acids, andinsoluble in alcohol. All three compounds are non-flammable.

HOW IT IS MADE

Tribasic calcium phosphate can be obtained directly fromrock and minerals such as apatite, a complex and impureform of calcium phosphate, or phosphorite, a mineral that

Calcium phosphate . Redatoms are oxygen; yellow atoms

are phosphorus; and theturquoise atoms are calcium.Gray sticks are double bonds.



CALCIUM PHOSPHATE

contains calcium phosphate mixed with other compounds.The compound can also be produced synthetically by reactingphosphoric acid (H3PO4) with solid calcium hydroxide(Ca(OH)2), or in the reaction between calcium chloride (CaCl2)and sodium triphosphate (Na5P3O10). Dibasic calcium phosphatecan also be produced in the former of these synthetic reac-tions by using an aqueous solution of calcium hydroxiderather than the solid compound. Monobasic calcium phos-phate is produced synthetically by adding excess phosphoricacid to a solution of either dibasic or tribasic calcium phos-phate and allowing the solution to evaporate.


Each form of calcium phosphate has its own uses. Thedibasic form is used as a nutrient and mineral supplementin animal foods and in certain processed foods, especiallycereals. In addition to its nutritional value, dibasic calciumphosphate acts as a dough conditioner, stabilizer, and thick-ener in foods. The compound is also used in dental productsto provide replacement for hydroxyapatite lost to decay orother factors.

The most common application of monocalcium phosphateis in fertilizers, where its function is to provide the phos-phorus that plants need to remain healthy and grow properly.

Interesting Facts

• The forms of calciumphosphate discussed hereare only three of manyways in which calcium,phosphorus, and oxygencombine to form calciumphosphate-type com-pounds. Another suchcompound is known ashydroxyapatite

(Ca5(PO4)3(OH)), whichmakes up about 70 percentof an adult tooth.

• Calcium phosphate is oneof the two most commoncompounds found in kidneystones. The second of thesecompounds is calciumoxalate (CaC2O4).


CALCIUM PHOSPHATE

It is also used as a food additive in baking powders and wheatflours where it serves to retain the proper acidity of the foodproduct to which it is added. It is also used, like the dibasicform, as a nutritional supplement in processed foods.

Tricalcium phosphate has the largest range of uses of thethree forms of the compound, the most important of whichare in the manufacture of fertilizers, the production of ceramicmaterials, and the preparation of other compounds of phos-phorus. The compound is also used:

• As a clarifying agent in the purification of sugar solutions;

• As a mordant in the dyeing of cloth;

• In the preparation of dental products;

• As a stabilizer for plastics;

• As a food additive to prevent a powdery product fromcaking (becoming compacted);

• As a nutritional supplement; and

• As a means of removing radioactive strontium (stron-tium-90) from milk that has been contaminated by theelement.

While none of the forms of calcium phosphate is flam-mable, they can all irritate the skin, eyes, and respiratorysystem. Tricalcium phosphate is the most hazardous of thefamily of compounds. Direct contact with the eyes may causesevere symptoms, including irritation and burning, resultingin damage to the cornea. The compound is also poisonousif taken internally. It can cause stomach pain, vomiting, andlow blood pressure. These problems occur when one is exposed

Words to Know

AQUEOUS Consisting of some materialdissolved in water.

MORDANT A substance used in dyeing andprinting that reacts chemically with both adye and the material being dyed to helphold the dye permanently to the material.

SYNTHESIS a chemical reaction in which somedesired chemical product is made fromsimple beginning chemicals, or reactants.



CALCIUM PHOSPHATE

to relatively large amounts of the compound. In the quantitiespresent in foods and other products with which consumerscome into contact, the compound poses little risk to users.


‘‘Calcium Phosphate.’’ Medline Plus.http://www.nlm.nih.gov/medlineplus/ency/article/002889.htm(accessed on September 28, 2005).

‘‘Dicalcium Phosphate.’’ Univar USAhttp://www.msdsvault.org//UNIVARUSA/33222770621C2A2E204EBB8825668F0061E8ED OPENDOCUMENT.PDF(accessed on September 28, 2005).

‘‘Tricalcium Phosphate.’’http://www.luminet.net/~wenonah/hydro/3capo.htm (accessedon September 28, 2005)


CALCIUM PHOSPHATE

OTHER NAMES:Calcium metasilicate

FORMULA:CaSiO3

ELEMENTS:Calcium, silicon,

oxygen


STATE:Solid





most other commonsolvents

Calcium Silicate

KE

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OVERVIEW

The term calcium silicate (KAL-see-um SILL-i-kate) appliesto a number of related compounds consisting of calcium,silicon, and oxygen, all of which tend to occur in a hydratedform. The most common of these forms is calcium metasili-cate, for which data are given above. Calcium silicates withthe formulas Ca2SiO4 and Ca3SiO5 are also well known.

Calcium silicate is a component of many minerals, includ-ing afwillite, akermanite, andradite, calcite, centrallasite, crest-moreite, diopside, eaklite, grammite, gyrolite, hillebrandite,larnite, and wollastonite. In its pure form, calcium metasilicateis a white to off-white color capable of absorbing up to two and ahalf times its weight of water. In this form, the hydrated powderretains its ability to flow freely. Addition of a mineral acid, suchas hydrochloric acid (HCl) results in the formation of a gel.

HOW IT IS MADE

Given its abundance in rocks and minerals, calcium meta-silicate and its cousins can be extracted from a variety of

Ca2+ Si O

O2+

O


natural sources. Nonetheless, the compound is usually pre-pared synthetically in order to ensure that is has the purityrequired for most commercial applications. The usual methodof preparation involves the addition of lime (calcium oxide;CaO) to diatomaceous earth, a material consisting of thefossil remains of single-celled algae known as diatoms. Thelime provides the calcium and the diatomaceous earth pro-vides the silicon dioxide (SiO2) required to make calciumsilicate.


The calcium silicates have a number of uses in industry.Among the most important applications are their uses inbuilding materials, such as some types of glass and cement(especially Portland cement), bricks and tiles for roofs, fire-proof ceilings, and building boards. The compound is also

Calcium silicate. Red atomsare oxygen; turquoise atom is

calcium; orange atom is silicon.Gray stick is a double bond.



CALCIUM SILICATE

used as a filler in the manufacture of paper and some typesof plastics, where it gives body to the final product.

Other applications of the calcium silicates include thefollowing:

• As an absorbent for liquids and gases in industrialprocesses;

• As a food additive, where it absorbs moisture and pre-vents a product from ‘‘caking’’ (becoming compacted);

• In road construction;

• As a refractory material in industrial furnaces;

• For the insulation of pipes and conduits;

• In the manufacture of paints and other types of coatingmaterials;

• In the preparation of certain types of cosmetics;

• In some fertilizers and insecticides; and

• In some pharmaceutical products, such as antacids.

There have been no reports of calcium silicate’s beinghazardous or harmful to humans or experimental animals. Aswith all chemicals, overexposure to large amounts of thecompound could result in irritation of the skin, eyes, andrespiratory system.

Interesting Facts

• One of the most commonbuilding materials in usetoday is Portland cement,made from a mixture ofoxides, including lime(calcium oxide), sand (silicondioxide), and aluminum,iron, and magnesiumoxides. When thesecomponents are mixed andwater is added, a complex

set of chemical reactionsoccur in which calciumsilicates are among themajor products formed.These calcium silicatesare responsible for thegreat strength for whichPortland cement productsare known.


CALCIUM SILICATE


‘‘Occupational Safety and Health Guideline for Calcium Silicate,Synthetic.’’ Occupational Health and Safety Administration.http://www.osha.gov/SLTC/healthguidelines/calciumsilicate/recognition.html#healthhazard (accessed on September 29,2005).

‘‘Scientific Principles.’’ Materials Science and Technology Teacher’sWorkshop.http://matse1.mse.uiuc.edu/~tw/concrete/prin.html (accessedon September 29, 2005).

‘‘Wollastonite.’’ CeramicMaterials.Info.http://ceramic materials.com/cermat/material/1705.html (accessedon September 29, 2005).

Words to Know

HYDRATE Chemical compound formed whenone or more molecules of water is addedphysically to the molecule of some othersubstance.

REFRACTORY Having a high melting point,resistant to melting. Refractory materials

are often used to line the interior ofindustrial furnaces.



CALCIUM SILICATE

OTHER NAMES:Anhydrous gypsum;

also see Overview forsynonyms of

hydrates

FORMULA:CaSO4

ELEMENTS:Calcium, sulfur,

oxygen

COMPOUND TYPE:Salt (inorganic)

STATE:Solid





most organicsolvents

Calcium Sulfate

KE

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OVERVIEW

Calcium sulfate (KAL-see-um SUL-fate) occurs in threeforms:

• anhydrous calcium sulfate (CaSO4); the anhydrous formof calcium sulfate is available in two forms, known asinsoluble anhydrite and soluble anhydrite;

• calcium sulfate dihydrate (CaSO4�2H2O), also known asmineral white, terra alba, light spar, precipitated cal-cium sulfate, native calcium sulfate, and by othernames;

• calcium sulfate hemihydrate (CaSO4�1/2H2O), also knownas plaster of Paris and dried gypsum;

The physical properties of the three forms of calciumsulfate differ somewhat from each other, but their chemicalproperties are essentially the same. Anhydrous calcium sul-fate and calcium hemihydrate are fine white odorless pow-ders or crystalline solids, while the dihydrate may occureither as a powder or as white lumps. Both hydrates are

Ca2+

2-

S

O

O

O O


converted to the anhydrous form upon heating as, for exam-ple: CaSO4�2H2O ! CaSO4 + 2H2O.

Anhydrous calcium sulfate is essentially insoluble inwater. As their names suggest, the soluble form of the com-pound (soluble anhydrite) is somewhat more soluble in waterthan is the insoluble form (insoluble anhydrite). The dihy-drate and hemihydrate are only slightly soluble in water.When water is added to the hemihydrate, a reaction occursthat results in the formation of a hard, solid mass (plaster ofParis) used in making casts, such as those used to holdbroken bones in place. Neither the anhydrous form of cal-cium sulfate or the dihydrate reacts with water in this way.

Both the anhydrous and dihydrate forms of calcium sul-fate occur naturally in the form of the minerals anhydrite,angelite, muriacite, and karstenite (CaSO4); and gypsum(CaSO4�2H2O). These minerals have been known to humansand used by them for thousands of years. The method forconverting natural gypsum to the hemihydrate (plaster of

Calcium sulfate. Red atomsare oxygen; turquoise atom is

calcium; and yellow atom issulfur. Gray sticks show doublebonds. P U B L I S H E R S R E S O U R C E

G R O U P

CALCIUM SULFATE


Paris) has also been known and used for a very long period oftime. Archaeologists have learned that the Egyptians devel-oped a method for converting gypsum to plaster of Paris,which was then used as mortars to join blocks in buildings,more than 5,000 years ago.

HOW IT IS MADE

Gypsum is an abundant mineral providing a ready nat-ural supply of calcium sulfate. The mineral usually consistsof a mixture of the anhydrous and dihydrate forms of cal-cium sulfate, which can be separated into its componentparts. Clay, sand, limestone, and other impurities are alsopresent in most gypsum deposits. The process of separationand purification begins by crushing natural gypsum andheating it in an open kettle to temperatures of 100�C to125�C (212�F to 257�F) for a few hours. Heating convertsthe gypsum to the hemihydrate or anhydrous calcium sulfatedepending on the temperature of the reaction. The solubilityof the final product can also be controlled by the temperatureused in the heating container and the time during which thematerial is heated.

Large amounts of calcium sulfate are also produced asthe by-product of other reactions or by synthetic processes.The production of phosphoric acid (H3PO4) from sulfuric acid(H2SO4) and phosphate rock, for example, results in the for-mation of calcium sulfate, which can be recovered and pur-ified. Calcium sulfate can also be produced in the reactionbetween other calcium compounds, such as calcium hydro-xide (Ca(OH)2) and sulfuric acid.


The most widely used form of calcium sulfate is thedihydrate, gypsum, which is an important raw material inthe construction industry. It is used in the manufacture ofPortland cement, in specialized plasters (known as gypsumplasters) for walls, in the production of wallboard, and incement blocks and mortars. Gypsum is also used extensivelyin agriculture as a conditioning agent that adds both cal-cium ions (Ca2+) and sulfate ions (SO42-) to the soil. Thecompound is also used as a raw material in the synthesis ofother calcium compounds and in the production of plasterof Paris.


CALCIUM SULFATE

The anhydrous form of calcium sulfate also has a numberof practical applications, the most important of which are inthe manufacture of cement and as a filler in the productionof paper. A filler adds body to paper, making it firmer,brighter, and easier to write, draw, and print on. Solubleanhydrite is used as a desiccant, which is a material thatremoves water from other substances. It is usually sold underthe trade name of Drierite�.

The primary use of calcium hemihydrate is, of course, inthe production of plaster of Paris. Plaster of Paris has anumber of important applications, such as:

• In the construction of arts and crafts projects, such asmasks, ceramics, and pottery;

• For the production of plaster casts used to immobilizebroken bones;

• As a building material in the manufacture of stucco,drywall, division panels, ceiling tablets, plaster board,and wall plaster.

Some other important applications of calcium sulfateinclude:

• As a firming agent in foods such as canned vegetables,soft-serve ice cream, regular ice cream, frostings, andgelatins;

• As an additive to animal feeds to provide the calciumand sulfate that animals need in their diets;

Interesting Facts

• Calcium sulfate has beenused in China for morethan 2,000 years tothicken soy milk in theproduction of tofu.

• One reason that calciumsulfate hemihydrate iscalled plaster of Paris isthat large deposits ofgypsum (from which plaster

of Paris is made) existnear the city of Paris,France. These depositswere long mined to obtainthe hemihydrate form ofcalcium sulfate.

• Ancient Romans usedplaster of Paris to castcopies of Greek statues.

CALCIUM SULFATE


• In the production of polishing powders;

• As a paint pigment (white); and

• In a variety of metallurgical processes, such as theconversion of zinc minerals to zinc metal.

Although nontoxic, calcium sulfate can irritate therespiratory tract if inhaled. It may cause symptoms such ascoughing, shortness of breath, and nosebleeds. The compoundcan also irritate the skin and eyes, causing redness and pain.Ingestion of the compound can cause stomach pains, nausea,and vomiting.


‘‘A Brief History of Plaster and Gypsum.’’ Association of Lifecasters International.http://www.artmolds.com/ali/history_plaster.html (accessed onDecember 10, 2005).

‘‘Calcium Sulfate.’’ National Organic Program. Agricultural Marketing Service.http://www.ams.usda.gov/nop/NationalList/TAPReviews/CaSO4.pdf (accessed on December 10, 2005).

‘‘Calcium Sulfate, Anhydrous, Powder.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/c0497.htm (accessedon December 10, 2005).

Dontsova, Katerina, et al. ‘‘Gypsum for Agricultural Use in OhioSources and Quality of Available Products.’’ Ohio State University Extension Fact Sheet.http://ohioline.osu.edu/anr fact/0020.html(accessedonDecember10,2005).

‘‘Gypsum Statistics and Information.’’ U.S. Geological Survey.http://minerals.usgs.gov/minerals/pubs/commodity/gypsum/(accessed on December 10, 2005).

Words to Know

DESICCANT A material that removes waterfrom other substances.




CALCIUM SULFATE

OTHER NAMES:Gum camphor; also

see Overview.

FORMULA:C10H16O


oxygen

COMPOUND TYPE:Cyclic ketone

(organic)

STATE:Solid


MELTING POINT:178.3�C to 178.8�C

(352.9�F to 353.4�F);varies depending on

isomer

BOILING POINT:207.4�C (405.3�F;

depends on isomer);some forms sublime

before boiling


ether, acetone,benzene, and other

organic solvents

Camphor

KE

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AC

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OVERVIEW

Camphor (KAM-for) is also known as gum camphor;2-camphanone; 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one; and1,7,7-trimethylbicyclo[2.2.1]-2-heptanone, among others. It isa volatile white waxy substance with a strong, characteristicodor and a bitter, cooling taste. Its odor has been described asfragrant, aromatic, pungent, or penetrating, similar to thatof mothballs. The compound is obtained from the camphortree, Cinnamomum camphora, which is native to many partsof the world, including the Indonesian islands of Java andSumatra, as well as China, Taiwan, Japan, and Brazil.

The first mention of camphor by a Westerner occurs inthe writings of the Venetian explorer Marco Polo (1254–1324)in the late thirteenth century. The Chinese had apparentlybeen using camphor for many centuries in the embalming oftheir dead and the manufacture of soap, among other applica-tions. The Japanese also had a long history of using thecompound in the preparation of varnish and ink, to dilutepaint, to burn for light, and to protect clothing from moths.

C

CH

HH

H

H

O

H

H

C

CH3

CH3H3C

C

C

C

C


Camphor was also used throughout Asia as a medicine totreat a wide variety of ailments, from upset stomach torheumatism.

HOW IT IS MADE

Camphor can be obtained from every part of the Cinna-momum camphora tree, including the trunk, branches, roots,and leaves. The compound is extracted from tree parts by

Camphor. Red atomsare oxygen; white atoms arehydrogen; black atoms are

carbon. P U B L I S H E R S



CAMPHOR

steam distillation and crystallization of the camphor. Thecamphor thus obtained is one of two possible isomers, thedextrorotary (or ‘‘+’’) form of the compound. (The other isomeris the levorotatory or ‘‘-’’ form.) Since the natural sources ofcamphor are inadequate to meet commercial demand, camphoris also made synthetically. The process begins by convertingthe straight-chain hydrocarbons in turpentine oil (C10H16)to a cyclic isomer, a-pinene (c-C10H16), which is then oxidizedto make camphor. Synthetic camphor differs from naturalcamphor in that it consists of both isomers of the compound,the dextrorotary (+) and levorotatory (-) forms. This differencehas no effect on the chemical properties of camphor, althoughit has some modest effect on its biological properties.


Camphor has a long history of medicinal use. Peoplehave used it as a liniment to treat muscle aches and arthri-tis; as a topical anesthetic; as a treatment for nervousnessand hysteria; to treat diarrhea, bronchitis, and infectiousfevers; and even as an injection to cure heart failure. Verylittle medical evidence exists for most of these treatments.As a result, its primary medicinal use today is in lotions andointments for the relief of mild pain and discomfort due toarthritis, rheumatism, and sore muscles. Some common pro-ducts that contain camphor are Absorbine Arthritic PainLotion�, Ben-Gay�, Campho-phenique�, Panalgesic�, Sloan’sLiniment�, and Vicks VapoRub�. In these preparations, thecompound acts as both a mild analgesic (pain-reliever) andantiseptic (an agent to prevent the growth of disease-causingmicroorganisms). Its pronounced odor may also help opennasal passages. Camphor is also an important ingredient in

Interesting Facts

Despite its name, thecamphor tree, Cinnamomum

camphora, does not producecinnamon. That compound

comes from a related member of the family, Cinnamo

mum zeylanicum.


CAMPHOR

some antipruritic agents, substances used to relieve thediscomfort of itching.

Although camphor is probably best known to most peo-ple because of its medicinal uses, the compound also has anumber of important industrial applications. For example, itis added to cellulose nitrate as a plasticizer, a substanceadded to plastic to make it softer and more flexible. Otheruses for camphor include:

• As a moth and mildew repellent in mothballs and mothflakes;

• In the embalming of dead bodies;

• In the manufacture of fireworks and explosives;

• As a preservative in pharmaceuticals and cosmetics;

• In the production of lacquers and varnishes; and

• As a chemical intermediary in the production of a num-ber of organic compounds.

One of camphor’s most serious disadvantages as a medi-cinal product is that it is poisonous. Drinking straight cam-phorated oil can kill a person. In smaller doses, it can causemental confusion, irritability, jerky movements of the armsand legs, neuromuscular hyperactivity, and seizures. Symp-toms can appear between five and ninety minutes after swal-lowing the camphor. In 1980, the United States Food andDrug Administration limited the amount of camphor allowedin consumer products to 11 percent. It also banned productsthat contain concentrated camphor, such as camphorated oiland camphorated liniment.

Words to Know

ANALGESIC A substance the relieves pain.

DISTILLATION A process of separating twoor more substances by boiling the mixtureof which they are composed and conden-sing the vapors produced at differenttemperatures.

ISOMERS Two or more forms of a chemicalcompound with the same molecularformula, but different structural formulasand different chemical and physicalproperties.


CAMPHOR


‘‘Camphor.’’http://www.innvista.com/health/herbs/camphor.htm (accessedon September 29, 2005).

‘‘Camphor.’’ Botanical.com.http://www.botanical.com/botanical/mgmh/c/campho13.html(accessed on September 29, 2005).

‘‘Camphor; Gum Camphor; Laurel Camphor. Camphora Officinarum.’’ Drugstore Museum.http://www.drugstoremuseum.com/sections/level_info2.php?level_id=71&level=2 (accessed on September 29, 2005).

See Also Cellulose Nitrate


CAMPHOR

OTHER NAMES:Carbonic anhydride;

carbonic acid gas

FORMULA:CO2

ELEMENTS:Carbon, oxygen

COMPOUND TYPE:Nonmetallic oxide

STATE:Gas


MELTING POINT:Not applicable;liquefies under

pressure at �56.56�C(�69.81�F)

BOILING POINT:Sublimes at �78.4�C

(�109�F)


slightly soluble inalcohol and some

other organicsolvents

Carbon Dioxide

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OVERVIEW

Carbon dioxide (KAR-bun dye-OK-side) is a colorless,odorless, tasteless, non-combustible gas that can also existunder pressure as a clear, colorless, odorless, tasteless liquidand as a white, snow-like solid commonly known as dry ice.When dry ice is warmed it sublimes (passes directly fromthe solid to the gaseous state without first melting) at�78.4�C (-109�F).

The true nature of carbon dioxide was discovered over anextended period of time beginning with the research of theFlemish physician and chemist Jan Baptista van Helmont(1580–1635?). In about 1603, van Helmont isolated a gasproduced during the combustion of wood and proved that itwas distinct from air. At the time, air was generally regardedas an element that could not be divided into separate compo-nents. Van Helmont called the gas gas sylvestre (‘‘wood gas’’),a substance we now know to be carbon dioxide. Credit forunderstanding the true nature of carbon dioxide also goes tothe Scottish chemist Joseph Black (1728–1799) who produced

C OO


carbon dioxide by heating calcium carbonate (CaCO3). Blackcalled the gas fixed air and conducted the first extensivestudies of its properties.

The first practical use for carbon dioxide was discoveredin the mid-eighteenth century by the English chemist JosephPriestley (1733–1804). Priestley found that passing carbondioxide into water produced a sparkling, refreshing drinkthat he predicted would one day become a great commercialsuccess. He was, of course, correct, since water containingcarbon dioxide is the basic component of which all sodadrinks are made.

HOW IT IS MADE

Carbon dioxide is produced in nature by a number ofreactions. Among the most common is the combustion(burning) of the fossil fuels (coal, oil, and natural gas). Thegas is also produced during the decay of organic material,the fermentation of carbohydrates by yeast, and the respira-tion of animals. In the laboratory, the simplest and mostdirect method of preparation is to treat a carbonate, suchas calcium carbonate, with an acid, such as hydrochloricacid (HCl).

Carbon dioxide is obtained commercially as the by-product of a number of industrial reactions. For example,when calcium carbonate is heated to produce lime (CaO),carbon dioxide is released and captured as a by-product. Thesteam reforming (refining) of petroleum results in the pro-duction of a mixture of gases known as synthesis gas, con-sisting of carbon dioxide, carbon monoxide, hydrogen, andnitrogen. Carbon dioxide can be separated from the othercomponents of synthesis gas for commercial uses. Carbondioxide also produces as a by-product of the manufacture ofammonia (NH3) by the Haber-Bosch process.

Carbon dioxide. Red atoms areoxygen and black atom iscarbon. Gray sticks show

double bonds. P U B L I S H E R S


CARBON DIOXIDE



Carbon dioxide plays an essential role in most biologicalprocesses that take place on Earth’s surface. Plants use car-bon dioxide as a raw material to make the carbohydrates onwhich their structures are based. When animals eat plants,those carbohydrates are then used to build and maintaintheir body structures.

In addition to its role in natural processes, carbon dioxidehas many commercial and industrial applications. One of themost important uses is in the carbonation of beverages.Although beers and sparkling wines contain carbon dioxidefrom natural sources (the fermentation of sugars byyeasts), nearly all carbonated beverages have their carbondioxide added artificially. The carbon dioxide adds a zestytaste to the beverage and helps to preserve it.

Interesting Facts

• Carbon dioxide is thefourth most abundant gasin the atmosphere (afternitrogen, oxygen, andargon) with a concentra-tion of about 0.036percent. Researchers havefound that the concentra-tion of carbon dioxide inthe atmosphere has beenincreasing at a regular ratefor at least the last fortyyears. They believe that thereason for this increase isthe escalating use of fossilfuels by humans to heathomes and offices; drivecars, trucks, trains, andairplanes; and to powerindustrial operations. Theyfurther suspect that anincrease in the amount of

carbon dioxide in theatmosphere may have sig-nificant long-term effectson the planet’s climate.

• Scientists have becomevery interested in a formof carbon dioxide knownas supercritical carbondioxide (SCCO2 or SC-CO2).Under the proper condi-tions of temperature andpressure, carbon dioxide(as SCCO2) behaves asboth a liquid and a gas atthe same time. This prop-erty has proved to be veryvaluable in using SCCO2 asa highly efficient solventthat has no environmentaldisadvantages.


CARBON DIOXIDE

Carbon dioxide is also used as a fire extinguishing agent.Its use for this purpose is based on the facts that it does notburn itself and is heavier than air. Thus, when sprayed on afire, carbon dioxide settles down on top of the flames andprevents oxygen from reaching the burning material. Thecarbon dioxide can be supplied in a variety of ways in a fireextinguisher. In some devices, carbon dioxide gas is pro-duced as the result of a chemical reaction that occurs withinthe fire extinguisher. In other devices, liquid carbon dioxideis released from the extinguisher.

Carbon dioxide is also used in gaseous, liquid, or solidform as a refrigerant. As a gas, it is used as the ‘‘workingfluid’’ in refrigerators, the fluid that circulates through therefrigerator changing back and forth from gas to liquid,absorbing heat in the process. In the form of dry ice, carbondioxide is a very efficient and convenient method for coolingobjects to very low temperatures (close to the sublimationpoint of carbon dioxide, about �78.4�C (�109�F).

Some other uses of carbon dioxide include the following:

• As an aerosol propellant;

• To provide an oxygen-free atmosphere in which to con-duct welding and other operations with flammablematerials;

• In the industrial manufacture of carbonates;

• For cloud seeding to promote modifications in theweather (increases or decreases in rain fall);

• In the fumigation of rice to preserve the product forextended periods of time;

• As an artificial smoke in theater productions;

Words to Know

SUBLIME Changing of states from solid togas without becoming liquid first.

SYNTHESIS GAS A mixture of several gases,such as carbon dioxide and hydrogen, used

to produce compounds such as methanoland ammonia that can be separated outfrom the synthesis gas.

CARBON DIOXIDE


• As a moderator to slow down the speed of neutronstraveling in a nuclear power plant;

• In the frozen food industry;

• To enrich the air in a greenhouse, providing additionalcarbon dioxide to promote plant growth; and

• For the hardening of foundry molds and cores.

In general, carbon dioxide poses little or not threat tohumans in concentrations to which one is normally exposed.Dry ice may pose a hazard if not handled carefully as its verylow temperature can cause damage to the skin.


‘‘Carbon Dioxide (CO2) Applications and Uses.’’ Universal Industrial Gases, Inc.http://www.uigi.com/carbondioxide.html (accessed on September29, 2005).

‘‘Carbon Dioxide, Oxygen, and the Air.’’ Skool.ie.http://www.skoool.ie/skoool/examcentre_jc.asp?id=1980(accessed on September 29, 2005).

‘‘Chemical of the Week: Carbon Dioxide.’’http://scifun.chem.wisc.edu/chemweek/CO2/CO2.html(accessed on September 29, 2005).

See Also Calcium Carbonate; Calcium Oxide


CARBON DIOXIDE

OTHER NAMES:None

FORMULA:CO

ELEMENTS:Carbon, oxygen


STATE:Gas



(�337.04�F)



water; soluble inalcohol andchloroform

Carbon Monoxide

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OVERVIEW

Carbon monoxide is a colorless, odorless, tasteless, toxicgas. It is one of the most common poisons in the environmentand is responsible for thousands of deaths and hospital emer-gency room visits each year in the United States. Carbonmonoxide is produced from fuel-burning appliances, such asspace heaters, furnaces, stoves, and vehicles. It is also a com-ponent of cigarette smoke. Carbon monoxide is flammable andcapable of forming an explosive mixture with air.

Under ideal circumstances, a carbon-containing fuel suchas charcoal, natural gas, or wood burns in air to form carbondioxide and water. Lacking an adequate supply of oxygen, atlow temperatures, or under certain other conditions, incom-plete combustion occurs. Incomplete combustion is a processin which a fuel is not completed oxidized. In such instances,carbon monoxide is produced along with carbon dioxide andwater. An inadequate supply of oxygen can occur in enclosed,poorly vented spaces, such as the interior of houses, garages,and cars.

C O


The discovery of carbon monoxide is usually credited tothe English chemist Joseph Priestley (1733–1804). Between1772 and 1799, Priestley investigated the properties of car-bon monoxide and recognized the difference between carbonmonoxide and carbon dioxide. The gas was first preparedsynthetically by the French chemist Joseph Marie Francoisde Lassone (1717–1788) in 1776, although he mistakenly iden-tified it as hydrogen. The correct chemical formula for car-bon monoxide was first identified by the English chemistWilliam Cruikshank (1745–1800) in 1800.

HOW IT IS MADE

A number of methods are available for the commercialproduction of carbon monoxide. In one procedure, air ispassed over hot coke, graphite, or anthracite coal to makeproducer gas, a mixture of carbon dioxide, carbon monox-ide, hydrogen, and water vapor. In a similar procedure,steam is passed over hot coke or graphite to make watergas, a mixture of carbon monoxide, carbon dioxide, hydro-gen, and nitrogen. In a third procedure, steam is mixed withnatural gas to form synthesis gas, consisting of carbondioxide, carbon monoxide, and hydrogen. In all three proce-dures, the carbon monoxide component of the gas mixtureproduced in the reaction can be separated out from theother gases.

Yet a fourth method for making carbon monoxideinvolves the partial oxidation of hydrocarbon gases obtainedfrom natural gas or petroleum. These gases consist of carbon-hydrogen compounds which, when oxidized, are converted tocarbon monoxide, carbon dioxide, and water. By controlling

Carbon monoxide. Red atom isoxygen and black atom is

carbon. Stick is a double bond.P U B L I S H E R S R E S O U R C E G R O U P

CARBON MONOXIDE


the amount of reactants used and the conditions of the reac-tion (temperature and pressure), the portion of carbon mon-oxide produced can be increased.


Carbon monoxide has three major industrial uses. Thefirst is in the synthesis of a large variety of organic com-pounds. For example, it takes part in a group of reactionsknown as the Fischer-Tropsch reactions in which carbonmonoxide is first reduced with hydrogen gas and then con-verted to any number of organic compounds that containoxygen. The gas is also used to make acetic acid, a majorindustrial chemical used in the synthesis of polymers andother organic products.

A second application of carbon monoxide, either by itselfor in conjunction with other gases, is as an industrial fuel.The gas burns very efficiently with the release of largeamounts of heat and relatively few undesirable by-products(the most important being carbon dioxide).

Interesting Facts

• Some authorities believethat the American writerEdgar Allan Poe (1809–1849)owed his wild imaginationand early death to chroniccarbon monoxide poison-ing, caused by the gaslighting used in his home.

• Public health authoritiesestimate that the numberof suicides resulting fromthe inhalation of carbonmonoxide fumes fromautomobiles has decreasedby about 80 percent sincethe introduction of catalytic

converters in cars. Catalyticconverters reduce theamount of carbonmonoxide released in acar’s exhaust.

• Carbon monoxide bonds tohemoglobin in the bloodstream 200 times asefficiently as does oxygen.This ability to excludeoxygen from the blood isresponsible for the toxiceffects caused by carbonmonoxide in the body.


CARBON MONOXIDE

A third industrial use for carbon monoxide is in therefining of metals. Most metal ores exist in the form ofoxides or sulfides when extracted from the earth. For exam-ple, the two most important ores of iron are magnetite(Fe3O4) and hematite (Fe2O3). After an ore has been mined,it is treated to remove the oxygen or sulfur in the ore toobtain a pure metal. Carbon monoxide is often used for thispurpose with oxide ores because it combines with oxygenfrom the ore to form carbon dioxide, leaving the metalbehind: Metal oxide + CO ! Metal + CO2.

Carbon monoxide is a highly toxic gas that has notice-able health effects even in relatively small concentrations.When the concentration of carbon monoxide reaches levelsof about 100 ppm (parts per million), an individual is likelyto experience mild headaches, fatigue, shortness of breath,and errors in judgment. As the concentration of carbon mon-oxide increases, these symptoms become more pronounced.Exposure to a concentration of more than 400 ppm for morethan three hours is likely to put a person at serious healthrisk. He or she may begin to lose consciousness and experi-ence serious disorientation. At concentrations of more than1,500 ppm, death is likely in less than an hour. These symp-toms vary somewhat depending on a person’s age and overallhealth.

Most governmental agencies have set a recommendedlimit of 35 ppm for periods of up to eight hours. For purposes

Words to Know


REDUCTION Chemical reaction in whichoxygen is removed from a substance orelectrons are added to a substance.



SYNTHESIS GAS A mixture of several gases,such as carbon dioxide and hydrogen, usedto produce compounds such as methanoland ammonia that can be separated outfrom the synthesis gas.

CARBON MONOXIDE


of comparison, the normal concentration of carbon monoxidein the atmosphere in an open area tends to be less than 1ppm. But in urban areas or other locations with many vehi-cles, gas heaters, wood burning stoves, or other sources ofcarbon monoxide, carbon monoxide levels can be muchhigher. Someone traveling inside a car on a busy freeway,for example, may be exposed to carbon monoxide levels of upto 25 ppm. Concentrations of up to 100 ppm have beenmeasured in the center of busy downtown urban areas.


‘‘Carbon Monoxide.’’ Chemical Fact Sheet. Plastics and ChemicalsIndustries Association.http://www.pacia.org.au/_uploaditems/docs/3.carbon_monoxide.pdf (accessed on October 2, 2005).

‘‘Carbon Monoxide Questions and Answers.’’ Consumer ProductSafety Commission. CPSC Document #466.http://www.cpsc.gov/cpscpub/pubs/466.html (accessed on October3, 2005).

Dwyer, Bob, et al. Carbon Monoxide: A Clear and Present Danger.

Mount Prospect, Ill.: ESCO Press, 2004.

Patnaik, Pradyot. Handbook of Inorganic Chemicals. New York:McGraw Hill, 2003, 1887 191.

See Also Acetic Acid; Carbon Dioxide


CARBON MONOXIDE

OTHER NAMES:Tetrachloromethane;

perchloromethane

FORMULA:CCl4

ELEMENTS:Carbon, chlorine

COMPOUND TYPE:Halogenated

hydrocarbon; alkylchloride (organic)

STATE:Liquid



BOILING POINT:76.8�C (170�F)


miscible with ethylalcohol, ether,

benzene, chloroform,and most other

organic solvents

Carbon Tetrachloride

KE

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OVERVIEW

Carbon tetrachloride (CAR-bun tet-ra-KLOR-ide) is a color-less, nonflammable liquid with a sweetish odor and a density1.5 times that of water. The compound is classified as ahalogenated hydrocarbon because all of the hydrogens inmethane (CH4), a hydrocarbon, have been replaced by halo-gen atoms (chlorine, in this case). Carbon tetrachloride wasfirst prepared in 1839 by German-born French chemist HenriVictor Regnault (1810–1878). Regnault made carbon tetra-chloride by reacting chloroform (trichloromethane; CHCl3)with chlorine: CHCl3 + Cl2 ! CCl4 + HCl.

Until the mid-twentieth century, carbon tetrachloride hada number of important applications, including use as a drycleaning fluid, a refrigerant, and an industrial and chemicalsolvent. It was also used in fire extinguishers. By the 1950s,however, evidence of the serious health hazards posed bycarbon tetrachloride began to accumulate, and its use wasdramatically cut. In 1970, the U.S. Food and Drug Administra-tion banned its use in consumer products in the United States.

Cl

ClCl Cl

C


Production of carbon tetrachloride was not seriouslyaffected in the long run by this ban, however, as a new usewas found for the chemical: the manufacture of chlorofluoro-carbons (CFCs). Between the 1930s and the 1970s, the chloro-fluorocarbons were among the most successful and widelyused of all synthetic organic compounds. They were used in anumber of applications, including as refrigerants, blowingagents, solvents, and cleaning agents. They were also used inthe production of a variety of organic compounds. In the1950s and the 1960s, demand for carbon tetrachloride wasincreasing at a rate of about 10 percent a year in response tothe demand for CFCs.

Eventually, that use of carbon tetrachloride was alsolessened. Studies conducted by American chemists MarioMolina (1943–) and F. Sherwood Rowland (1927–) showed thatCFCs were responsible for the destruction of the Earth’sozone layer, posing potentially serious health hazards toplants and animals living on the planet. In response to thisdiscovery, the world’s nations agreed to cut back on the

Carbon Tetrachloride. Blackatom is carbon; green atoms

are chlorine. All sticks aresingle bonds. P U B L I S H E R S


CARBON TETRACHLORIDE


production of CFCs and the compounds from which they aremade. According to the Montreal Protocol on SubstancesThat Deplete the Ozone Layer, adopted in 1987, the produc-tion of carbon tetrachloride for use as a raw material in themanufacture of CFCs was to be first reduced, and thenbanned entirely by the year 2000. As a result, the productionof carbon tetrachloride and its use in modern society hasdiminished considerably.

HOW IT IS MADE

Carbon tetrachloride is now made by a method inventedmore than a century ago. Carbon disulfide (CS2) is treatedwith chlorine gas, producing sulfur monochloride (S2Cl2) andcarbon tetrachloride: CS2 + 3Cl2 ! CCl4 + S2Cl2.

This process is very efficient because the sulfurmonochloride can then be treated with additional carbon

Interesting Facts

• Before the ban imposed bythe Montreal Protocol,more than 90 percentof the chloroform pro-duced was used in themanufacture of chloro-fluorocarbons.

• Although carbon tetra-chloride was once used asa fire extinguisher, thisuse had its potential risks.When used on electricalfires, carbon tetrachloridecan react with oxygen inthe air to produce phos-gene (CCl2O), a poisonousgas used by Germanyarmies during World War I(1914–1918).

• The carcinogenic effectsof carbon tetrachloride arenow thought to resultfrom the fact that thecompound is convertedby enzymes in the bodyto phosgene, which thenattack cells and genes,initiating the processes bywhich cancer develops.

• Researchers have discov-ered that the bacteriumShewanella oneidensis iscapable of degradingcarbon tetrachloride, sug-gesting a possible simpleand safe way to clean upareas contaminated withthe compound.



disulfide to produce more carbon tetrachloride: CS2 + 2S2Cl2

! CCl4 + 6S.

A relatively small amount of carbon tetrachloride is alsomade in the reaction between methane gas (CH4) and chlorinegas at temperatures of 250�C to 400�C (500�F to 750�F):CH4 + 4Cl2 ! CCl4 + 4HCl.


The effect of bans on the production of carbon tetra-chloride in recent decades has been dramatic. Productionof the compound in the United States dropped from morethan 50,000 metric tons (55,000 short tons) in 1989 to lessthan 2 metric (2.2 short tons) in 1998. The compoundcannot be used in any consumer or household productsand has only a limited number of industrial applications.In general, its use is restricted to those situations in whichno satisfactory substitute has been found. Some of theseuses include:

• Certain specific and limited types of refrigeration sys-tems;

• Degreasing metals;

• The manufacture of certain electronic products;

• Additives for some kinds of gasoline;

• The recovery of tin from tin plating operations;

• The fumigation of limited types of grains;

• Solvents for a number of industrial operations.

The average person is likely to come into contact withcarbon tetrachloride in one of three ways: by inhalingvapors of the compound, by ingesting (swallowing) the com-pound or any product in which it is an ingredient, and (to alesser extent), through the skin. The primary health risksfrom exposure to carbon tetrachloride involve damage tothe liver and kidneys and, at high doses, the central nervoussystem. Some symptoms associated with exposure to carbontetrachloride include soreness of the liver or kidneys, nau-sea, headaches, drowsiness, and disorientation. Althoughstrong evidence is lacking, the U.S. Environmental Protec-tion Agency has labeled carbon tetrachloride as a probablecarcinogen.




‘‘Carbon Tetrachloride.’’ 11th Report on Carcinogens. NationalToxicology Program.http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s029carb.pdf (accessed on December 29, 2005).

‘‘Carbon Tetrachloride.’’ International Programme on ChemicalSafety.http://www.inchem.org/documents/ehc/ehc/ehc208.htm#SubSectionNumber:3.2.1 (accessed on December 29, 2005).

‘‘Carbon Tetrachloride.’’ Matheson Tri Gas.http://www.matheson trigas.com/msds/MAT04310.pdf (accessedon December 29, 2005).

‘‘Carbon Tetrachloride.’’ National Safety Council.http://www.nsc.org/library/chemical/carbonte.htm (accessed onDecember 29, 2005).

‘‘Chemical Fact Sheet: Carbon Tetrachloride.’’ Spectrum Laboratories.http://www.speclab.com/compound/c56235.htm (accessed onDecember 29, 2005).

See Also Chloroform

Words to Know


MISCIBLE Able to be mixed; especiallyapplies to the mixing of one liquid withanother.

OZONE LAYER A region of Earth’s atmo-sphere that contains a large quantity ofozone, which absorbs some of the sun’sradiation.



OTHER NAMES:None

FORMULA:(C6H10O5)n


oxygen

COMPOUND TYPE:Polysaccharide

(carbohydratepolymer; organic)

STATE:Solid

MOLECULAR WEIGHT:Very large, in excess

of 100,000 g/mol

MELTING POINT:Decomposes at

temperatures above260�C (500�F)



all common organicsolvents

Cellulose

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OVERVIEW

Cellulose (SELL-you-lohs) is a colorless to white, tasteless,odorless, polysaccharide fiber found in the cell walls of allland plants and some bacteria, seaweeds, algae, and fungi.Polysaccharides (the term means ‘‘many sugars’’) are poly-mers consisting of monosaccharide (simple sugar) monomersjoined together in very large molecules. The monomer ofwhich cellulose is made is glucose, also known as blood sugar,dextrose, or grape sugar. The subscript ‘‘n’’ at the end of thechemical formula indicates that a large number of thesemonomers combine to make the polymer. Cellulose providesthe structural support for plants and other organisms inwhich it occurs. It is generally regarded as the most commonorganic compound found in nature.

Cellulose never occurs in nature in a pure form. Cotton isthe purest natural form, consisting of about 90 percentcellulose. Flax (linen fiber) consists of about 70 to 75 percentcellulose, wood of about 40 to 50 percent cellulose, andseaweeds and algae of about 25 to 30 percent cellulose.

O HO

HO

HO

HO

OC

C

CC

OO

OHCC CC

C

HH

HH

CC

OH

OHO

C

n


Cellulose was first discovered in 1819 by the Frenchnaturalist Henri Braconnot (1781–1855). The compound wasfirst isolated and analyzed fifteen years later by the Frenchbotanist Anselme Payen (1795–1871), who gave it its modernname of cellulose based on its origin (‘‘cell’’) plus the suffix -ose.The earliest chemical studies of cellulose were conductedby a team of English chemists, Charles Frederick Cross(1855–1935), Edward John Bevan (1856–1921), and ClaytonBeadle (1868–1917), who identified the compound we nowknow as cellulose and reported on its structure and proper-ties in the 1890s and early 1900s.

Cellulose, in its natural forms such as wood, cotton, andlinen, has countless numbers of uses as food, clothing, con-struction materials, and other applications. It also serves as

Cellulose. Red atoms areoxygen; white atoms

are hydrogen; and black atomsare carbon. P U B L I S H E R S


CELLULOSE


the raw material in making derivatives such as celluloseacetate, cellulose nitrate, and cellulose xanthate with manyother uses and applications.

HOW IT IS MADE

Cellulose is synthesized in plants and some microorgan-isms through the process known as photosynthesis. In thatprocess, carbon dioxide (CO2) and water (H2O) are combinedin a complex series of reactions to produce glucose (C6H10O5)and oxygen (O2). Glucose molecules are then linked to eachother to from successively larger and more complex mole-cules, eventually resulting in the formation of cellulose.

Commercially, most cellulose is extracted from woodby one of two methods, the kraft (sulfate) process or the

steam explosion process. The product of these reactions iswood pulp, which consists primarily of cellulose. In the kraft

process, wood chips are treated with a solution of sodiumhydroxide (NaOH) and sodium sulfide (Na2S) at temperatures

of about 175�C (350�F) for two to six hours. This processusually results in a yield of about 40 to 45 percent wood

pulp. The pulp is then treated with a bleaching agent, suchas calcium or sodium hypochlorite (Ca(OCl)2 or NaClO) orchlorine dioxide (ClO2) to remove the color of lignin and

other impurities.

In the steam explosion process, wood chips are satu-rated with moisture and then exposed to temperatures of200�C to 250�C (400�F to 500�F) at pressures of one to fiveatmospheres. In this process, cellulose fibers are physicallyseparated from lignin fibers, which are the other majorconstituent of wood. In either process, yields of up to99 percent pure cellulose can be obtained.

Interesting Facts

• Scientists estimate thatplants worldwide synthe-size up to one trillion

metric tons of celluloseannually.


CELLULOSE


The number of products made from pure cellulose isalmost endless. The largest volume of such productsinclude paper and paper products, including (with 2001

production numbers): newsprint (5.8 million metric tons;6.4 million short tons), printing and writing paper (22.1

million metric tons; 24.4 million short tons), packagingand related uses (3.9 million metric tons; 4.3 million short

tons), tissue paper (6.4 million metric tons; 7.0 millionshort tons), containerboard (26.6 million metric tons;

29.3 million short tons), and boxboard (7.7 million metrictons; 8.5 million short tons). Other uses of celluloseinclude:

• Manufacture of cotton products, such as items of cloth-

ing, sheeting, and industrial fabrics;

• Production of other organic products, especially ethanol(ethyl alcohol; grain alcohol) and methanol (methyl

alcohol; wood alcohol);

• As insulation and soundproofing;

• As a food additive, where it is used to thicken and addbulk to food products;

• In equipment used in analytical chemistry, such aschromatographic devices used to separate the compo-nents of a mixture.

A major industrial use of cellulose is in the preparation

of various cellulose derivatives, primarily cellulose acetate,cellulose nitrate, and cellulose xanthate, each of which has anumber of applications.

Words to Know


SYNTHESIS A chemical reaction in which somedesired chemical product is made fromsimple beginning chemicals, or reactants.

CELLULOSE



‘‘Cellulose.’’ Fibersource.http://www.fibersource.com/f tutor/cellulose.htm (accessed onSeptember 30, 2005).

‘‘Cellulose.’’ London South Bank University.http://www.lsbu.ac.uk/water/hycel.html (accessed on September 30, 2005).

‘‘Cellulose Processing.’’ Organic Materials Review Institute.http://www.omri.org/cellulose_final.pdf (accessed on September30, 2005).

Cross, Charles, Clayton Beadle, Edward Bevan. Cellulose. An Out

line of the Chemistry of the Structural Elements of Plants,

with Reference to Their Natural History and Industrial Uses.

Elibron. Replica of 1895 edition by Longmans, Green, and Co.,London.http://www.elibron.com/english/other/item_detail.phtml?msg_id=10006054 (accessed on September 30, 2005).

See Also Cellulose Acetate; Cellulose Nitrate; CelluloseXanthate


CELLULOSE

OTHER NAMES:Nitrocellulose;

nitrocotton;guncotton; pyroxylin

FORMULA:C12H16N4O18


nitrogen, oxygen

COMPOUND TYPE:Carbohydrate poly-

mer (organic)

STATE:Solid

MOLECULAR WEIGHT:Varies, but very large


ignites at about170�C (340�F)


SOLUBILITY:Insoluble in water,alcohol, ether, and

most organicsolvents; also see

Overview

Cellulose Nitrate

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OVERVIEW

Cellulose nitrate (SELL-you-lohs NYE-trate) is a derivativeof cellulose made by adding nitric acid (HNO3) to cellulose.Its physical properties tend to differ somewhat depending onthe relative amount of nitrogen present in the compound.For example, the so-called ‘‘high nitrogen’’ form is soluble inboth acetone but insoluble in an alcohol/ether mixture. The‘‘low-nitrogen’’ form is soluble in both solvents. Cellulosenitrate is available in a variety of forms, ranging from color-less to white flakes or powder to a liquid or semi-solid gel-likematerial.

Cellulose nitrate was first discovered in 1845 by theSwiss-German chemist Christian Friedrich Schonbein (1799–1868). The story is told that Schonbein used his wife’s cottonapron to clean up some nitric acid that he had spilled on hislaboratory floor. He was amazed to discover that the cottonand nitric acid reacted to form a new compound thatexploded when heated, releasing a puff of black smoke. Heimmediately recognized the potential application for the new

n

O

C

H

H O

C

H

H

H

C

C

H2C

NO2

OH

NO2

C

O

O


material as an explosive and suggested the name guncottonfor it. He developed a more efficient method for making theproduct and, within a short period of time, guncotton hadbecome very popular as an explosive for both constructionand military purposes.

Researchers soon found that modifying the way in whichcellulose nitrate is prepared could significantly change itschemical and physical properties, and, therefore, its uses. Forexample, the British inventor Alexander Parkes (1813–1890)experimented with using a variety of solutions to dissolvecellulose nitrate, after which the material could be precipitatedin one or another form. At first he called the reformulatedcellulose nitrate ‘‘synthetic ivory,’’ because of its similarity tonatural ivory, but later referred to the product as parkesine,named after himself. He was unable to obtain financingneeded for the commercial manufacture of his invention,however, and it fell to an American inventor, John WesleyHyatt (1837–1920) to reinvent a similar product less than adecade later. Hyatt and his brother Isaiah developed a mix-ture of cellulose nitrate and camphor that was an even more

Cellulose nitrate. Red atomsare oxygen; white atoms

are hydrogen; black atoms arecarbon; and blue atoms

are nitrogen. P U B L I S H E R S


CELLULOSE NITRATE


satisfactory substitute for ivory than was Parke’s parkesine.The Hyatts obtained a patent for their new product, towhich they gave the name celluloid. Originally developedto meet a growing demand for an ivory-like material thatcould be use to make billiard balls, celluloid eventually hada number of other applications, including false teeth andphotographic film.

HOW IT IS MADE

Cellulose nitrate is produced in essentially the same wayas it was (albeit accidentally) by Christian Schonbein in 1845.A mixture of nitric acid and sulfuric acid are added to cellulosein one of various forms (as wood pulp, powder, flakes, or acolloidal mixture with water, for example). The properties ofthe product formed depend on the relative quantities of eachreagent used and the conditions under which the reaction iscarried out. One of the most important variables is the amount

Interesting Facts

• Cellulose nitrate was firstused for the manufactureof photographic film in1889 by the EastmanKodak company. Filmsmade in that era are highlyunstable, with a tendencyto catch fire sponta-neously. Efforts are nowunder way to protect andpreserve some classicmotion pictures originallycaptured on cellulosenitrate film that areunlikely to survive formany more years withoutsuch treatment.

• Although the Hyatt billiardballs made out of celluloid

were very popular at first,they had one seriousdisadvantage: They had atendency to explode uponcontact with each other.

• Items of clothing madefrom cellulose nitratein the late nineteenthcentury were sometimesknown as ‘‘mother-in-law’’clothing. They were soflammable that somepeople thought that theitem of clothing alongwith a cigarette lighterwas the perfect giftfor an unappreciatedmother-in-law.


CELLULOSE NITRATE

of nitrogen present in the cellulose nitrate formed. The morenitrogen present, the less stable the compound is and themore appropriate it is for use as an explosive. The less nitro-gen present, the more stable the compound, and the moresuitable it is for household and commercial applications.


Cellulose nitrate continues to be used as an explosive,most commonly in a product known as smokeless gunpow-der. The name comes from the fact that, when ignited, thecompound produces less smoke than is the case with mostother explosives. Smokeless gunpowder is used primarilyfor smaller weapons, such as artillery rockets and projec-tiles. A solution of cellulose nitrate dissolved in ether,known as collodion, has been used for a number of applica-tions since its discovery independently in 1846 by theFrench chemist Louis-Philippe Menard (dates not available)and the American physician Dr. J. P. Maynard (dates notavailable). These uses include the coating of wounds; pre-paration of bandages, surgical dressings, and other medicalparaphernalia; the production of photographic film; and themanufacture of laboratory equipment and devices. Cellulosenitrate is also used as a coating material in fast-dryingautomobile lacquers, on the cloth used to cover hardboundbooks, and as a leather covering.

Cellulose nitrate poses two major health risks. First, oldfilm made of cellulose nitrate has a tendency to deteriorateand decompose. That process results in the release of oxides ofnitrogen, which may be toxic to a greater or lesser degree.This problem is of special concern to people who have occasionto work with old films, but not usually to the general public.Second, cellulose nitrate is a very flammable material thatignites when exposed to even minimal flames or sparks. Mostproducts that contain cellulose nitrate today have been treatedto minimize that risk. However, products that were mademany years ago do not have the same protection and may posesafety risks to people who come into contact with them.


‘‘Caring for Cellulose Nitrate Film.’’ Conserve O Gram.http://www.cr.nps.gov/museum/publications/conserveogram/14 08.pdf (accessed on September 30, 2005).

CELLULOSE NITRATE


‘‘Cellulose Nitrate.’’ Conservation and Art Material EncyclopediaOnline.http://www.mfa.org/_cameo/frontend/material_description.asp?name=cellulose+nitrate&language=1 (accessed on September 30,2005).

‘‘DiscoverLightTM Membrane.’’ Pierce Biotechnology.http://www.piercenet.com/files/5186.pdf (accessed on September30, 2005).

Fox, Berry. ‘‘Not Fade Away.’’ New Scientist (March 1, 2003); 40.

‘‘Nitrocellulose Applications, Characterisation, Production andStorage.’’ Bayer Material Science.http://www.azom.com/details.asp?ArticleID=2785 (accessed onSeptember 30, 2005).

See Also Cellulose; Cellulose Acetate; Cellulose Xanthate


CELLULOSE NITRATE

OTHER NAMES:Viscose rayon;

xanthate rayon

FORMULA:[C6H7O2(OH)2

OCS2Na]n


oxygen, sulfur,sodium

COMPOUND TYPE:Polymer

STATE:Solid

MOLECULAR WEIGHT:Very large (50,000 to

100,000 g/mol)



SOLUBILITY:Soluble in aqueous

caustic solutions

Cellulose Xanthate

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OVERVIEW

Cellulose xanthate (SELL-you-lohs ZAN-thate) is a com-pound produced from cellulose in the viscose process formaking rayon. The subscript ‘‘n’’ in the chemical formulaindicates that many molecules chain together to makeup the polymer. In this case, between 200 and 400 C6H7O2

(OH)2OCS2Na molecules combine to make a molecule of cellu-lose xanthate.

Although rayon is made from a naturally-occurringmaterial, cellulose, it is regarded as a synthetic product. Itwas the first synthetic fiber made by humans. The methodfor making rayon was discovered in about 1891 by threeEnglish chemists, Charles Frederick Cross (1855–1935),Edward John Bevan (1856–1921), and Clayton Beadle (1868–1917). The discovery occurred while the three chemists werelooking for a way of making artificial silk. Although silk isan excellent fiber for making clothes and other materials, ithad to be exported from Japan and was, therefore, veryexpensive.


The first plant for the manufacture of rayon in the Uni-ted States was built in 1910 by the newly-formed ViscoseCorporation of America. Sales of the new product were slowat first, but by 1925, rayon had become more popular thansilk. Today, the Cross-Bevan-Beadle method of making rayonis only one of four processes used by the industry to makethe fiber.

HOW IT IS MADE

The process to make rayon begins with wood pulp orwood chips, usually from spruce or pine trees. The wood istreated with carbon disulfide (CS2), which converts cellulosein the wood to cellulose xanthate. The purpose of this step isto change an insoluble material (cellulose) into a solublematerial (cellulose xanthate). The cellulose xanthate is thendissolved in sodium hydroxide (NaOH), a strong alkali, form-ing a thick, viscous solution. The viscosity of the solution isresponsible for the name given to this method of makingrayon, the viscose process.

The cellulose xanthate solution is then allowed to standfor eight to ten hours in a ‘‘ripening room.’’ During this period,the cellulose xanthate slowly gives up its carbon disulfideand reverts to cellulose. The end result of these steps is therecovery of cellulose in a form that is easier to work with andfrom which long fibers can be made. The fibers are producedby forcing cellulose from the viscous solution through platescalled spinnerettes with many small holes in them.

Interesting Facts

Rayon was first sold in theUnited States as ‘‘artificialsilk.’’ But manufacturersthought the word ‘‘artificial’’would not appeal to consumers. So they held a contestwith a $1,000 prize to choosea better name for the fabric.

More than 10,000 nameswere suggested, but thecommittee appointed tochoose a winner rejected allof the names. Finally, amember of the committeesuggested the word rayon,French for ‘‘a ray of light.’’


CELLULOSE XANTHATE


Rayon has many properties that make it a desirablefabric. It has a soft, silky feel that is comfortable to the skin.Its fibers are strong, abrasion resistant, easy to dye, andresistant to bleaches and most chemicals. Electric chargesdo not collect on the fiber, allowing it to remain static-freeand to hang smoothly from the body. Rayon does have somedisadvantages. It tends to wrinkle easily, shrinks when itgets wet, and is very flammable. Among the many productsmade from rayon are the following:

• Clothing, such as suits, dresses, sports shirts, ties, lin-gerie, and work clothes;

• Domestic textiles, such as upholstery, curtains, drapes,bedspreads, sheets, and blankets; and

• Industrial textiles, such as reinforcing threads in rub-ber products, such as tires, hoses, and conveyor belts;braided cords; and tapes.

Rayon is very flammable, probably its greatest disadvan-tage in commercial products. During the late 1940s and early1950s, a number of accidents were reported in which rayonclothing caught fire, resulting in injury or death to wearers.In response to this problem, the U.S. Congress passed theFlammable Fabrics Act of 1953 (FFA), banning the sale of anyfabric (such as rayons) likely to catch fire. Since passage ofthe FFA, manufacturers who use rayon in their productsmust treat the fiber in some way to prevent it from catchingfire.

Words to Know

ALKALI A strong base.

AQUEOUS SOLUTION A solustion that con-sists of some material dissolved in water.

CAUSTIC Strongly basic or alkaline, capableof irritating or corroding living tissue.


VISCOUS Syrupy material that flows slowly.


CELLULOSE XANTHATE


‘‘Rayon Fiber (Viscose).’’ Fibersource.http://www.fibersource.com/f tutor/rayon.htm (accessed onSeptember 14, 2005).

‘‘Rayon Fibers.’’ Raghavendra R. Hegde, Atul Dahiya, andM. G. Kamath.http://www.engr.utk.edu/mse/pages/Textiles/Rayon%20fibers.htm (accessed on September 14, 2005).

‘‘Rayon Viscose.’’http://www.swicofil.com/viscose.html (accessed on September14, 2005).

See Also Cellulose, Cellulose Nitrate


CELLULOSE XANTHATE

OTHER NAMES:Trichloromethane,

trichloroform,methane trichloride,

methenyl trichloride,methyl trichloride

FORMULA:CHCl3


chlorine


hydrocarbon, alkylhalide (organic)

STATE:Liquid






acetone, benzene, andother organic

solvents

Chloroform

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OVERVIEW

Chloroform (KLOR-oh-form) is a clear, colorless, flam-mable, volatile liquid with a characteristic odor and a sweettaste. It was discovered almost simultaneously in 1831 byAmerican chemist Samuel Guthrie (1782–1848), French che-mist Eugene Soubeiran (1797–1858), and German chemistJustus von Liebig (1803–1873). The chemical structure of thecompound was determined by French chemist Jean-Baptiste-Andre Dumas (1800–1884), who suggested its modern nameof chloroform in 1834 or 1835. The compound’s anestheticeffects on animals were first observed by French physio-logist Marie Jean-Pierre Flourens (1794–1867) in 1847.

The potential value of chloroform as an anesthetic forhumans was immediately evident. In Great Britain, Liverpoolchemist David Waldie (1813–1889) suggested to a surgeonfriend of his, Sir James Young Simpson (1811–1870), that hemight try using chloroform instead of ether to ease the painof childbirth with his patients. On the evening of November4, 1847, Simpson and two physician friends experimented

Cl

ClCl

H

C


with chloroform to test its effects and all three passed out.Simpson was convinced of chloroform’s value as an anes-thetic and began using it in his medical practice. He did thisover the objections of many clergymen of the era whobelieved that women should suffer the pain of childbirthbecause of Eve’s actions in the Garden of Eden, as describedin the Bible. The use of chloroform as a painkiller soonspread widely throughout Great Britain and other countriesof the world.

In the twenty-first century, chloroform has been almostentirely replaced as an anesthetic by other compounds that aremore effective and have fewer undesirable side effects. Thecompound is now used almost exclusively for the productionof hydrochlorofluorocarbons (HCFCs), compounds developed toreplace chlorofluorocarbons (CFCs) that have been bannedbecause of their harmful effects on Earth’s ozone layer.

HOW IT IS MADE

Chloroform is produced commercially by the reactionbetween chlorine gas and methane gas. In this reaction, each

Chloroform. White atom ishydrogen; black atom is carbon;and green atoms are chlorine.


CHLOROFORM


of the four hydrogens in methane is replaced, one at a time,by chlorine atoms. The reaction must be carefully controlled,therefore, to ensure that maximum amounts of the desiredproduct (chloroform, in this case) are obtained.

Chloroform can also be produced in the reaction betweenacetone and bleaching powder (CaOCl2) in the presence ofsulfuric acid (H2SO4): 2CH3COCH3 + 6CaOCl2 ! 2CHCl3 +(CH3COO)2Ca + 3CaCl2 + 2Ca(OH)2.


In the early twenty-first century, more than 90 percentof the chloroform produced in the United States is used inthe preparation of hydrochlorofluorocarbons (HCFCs). HCFCsare compounds consisting of carbon, hydrogen, chlorine, andfluorine. They were developed in the 1980s to replace thechlorofluorocarbons (CFCs) that, at the time, were widelyused for a number of industrial applications. Replacing CFCshad become necessary because they were also destroying the

Interesting Facts

• The debate over the use ofchloroform as an anes-thetic during childbirthwas largely resolved in1853 when Queen Victoria(1819–1901) chose to havethe procedure during thebirth of her son PrinceLeopold (1853–1884).

• Chloroform is recom-mended for the removal oflipstick stains.

• At one time, chloroformwas used internally(usually in small doses) totreat a variety of medicalproblems, including

cholera, gonorrhea, colic,cramps, spasms, andconvulsions. Improperdoses led to problems thatwere more serious thatthose being treated,including coma and death.

• Chloroform was once usedin a number of consumerand household products,including toothpastes,cough syrups, and skinointments. Its use forthese purposes wasbanned in the UnitedStates in 1976.


CHLOROFORM

ozone layer in the stratosphere that protects plants andanimals on Earth’s surface from harmful ultraviolet radiation.

Chloroform is used to make one specific HCFC known asHCFC-22. HCFC-22 is also known as Freon 22, halocarbon 22,fluorocarbon 22, or R22. By 2003, an estimated 600 millionmetric tons (660 million short tons) of chloroform werebeing used in the United States for all commercial purposes.Of the HCFC-22 produced, about 70 percent was being used asa refrigerant, while the remaining 30 percent went for thesynthesis of polymers.

In addition to its use in the production of HCFC-22,chloroform has a number of other minor uses, including:

• As a solvent for fats, oils, waxes, rubber, and a numberof pharmaceuticals;

• In the manufacture of certain dyes and pesticides;

• As a cleansing agent in various industrial operations;

• In fire extinguishing systems;

• As a glue for methyl methacrylate products; and

• As a laboratory reagent.

Long-term prospects for chloroform are not very promis-ing since the production of HCFCs is scheduled to be phasedout over time. Although they have less serious effects onozone than do the CFCs, they are still regarded as a threatand their use has been restricted under provisions of theMontreal Protocol on Substances that Deplete the OzoneLayer. The U.S. Environmental Protection Agency plans toban the use of HCFC-22 under the Protocol by 2010.

Words to Know

ANESTHETIC A substance that is used totemporarily deaden the feeling in a part ofthe body or to make a person unconscious.



VOLATILE Able to turn to vapor easily at arelatively low temperature.

CHLOROFORM


Chloroform is an irritant to the skin, eyes, and respira-tory system. Moderate, short-term exposure may cause red-ness, pain, and dryness of the skin; redness and pain in theeyes; and coughing, nausea, headache, dizziness, drowsiness,vomiting, abdominal pain, and unconsciousness. At higherdoses and longer exposure, chloroform is believed to causeserious damage to the liver and kidneys. It is also thought tobe a carcinogen.


‘‘Chloroform.’’ 11th Report on Carcinogens. National ToxicologyProgram.http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s038chlo.pdf (accessed on December 29, 2005).

‘‘Chloroform.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/ehc/ehc/ehc163.htm(accessed on December 29, 2005).

‘‘Occupational Safety and Health Guideline for Chloroform.’’ Occupational Safety & Health Administration.http://www.osha.gov/SLTC/healthguidelines/chloroform/recognition.html (accessed on December 29, 2005).

Stratmann, Linda. Chloroform: The Quest for Oblivion. PhoenixMill, UK: Sutton Publishing Co., 2003.

‘‘ToxFAQsTM for Chloroform.’’ Agency for Toxic Substances andDisease Registry.http://www.atsdr.cdc.gov/tfacts6.html (accessed on December29, 2005).

See Also Carbon Tetrachloride


CHLOROFORM

FORMULA:Varies; see Overview.

ELEMENTS:Carbon, hydrogen,oxygen, nitrogen,

magnesium


STATE:Solid

MOLECULAR WEIGHT:608.96–907.47 g/mol

MELTING POINT:Chlorophyll a: 152.3�C(306.1�F); Chlorophyll

b: 125�C (257�F)


SOLUBILITY:Chlorophyll a and b

are insoluble in water,soluble in alcohol,

ether, and oils

Chlorophyll

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OVERVIEW

Chlorophyll (KLOR-uh-fill) is the pigment that givesplants, algae, and cyanobacteria their green color. The namecomes from a combination of two Greek words, chloros,meaning ‘‘green’’ and phyllon, meaning ‘‘leaf.’’ Chlorophyll isthe substance that enables plants to create their own foodthrough photosynthesis.

At least five forms of chlorophyll exist. They are:

• chlorophyll a (also known as a-chlorophyll), with a for-mula of C55H72O5N4Mg

• chlorophyll b (also known as b-chlorophyll), with a for-mula of C55H70O6N4Mg

• Chlorophyll c1, with a formula of C35H30O5N4Mg

• Chlorophyll c2, with a formula of C35H28O5N4Mg

• Chlorophyll d, with a formula of C54H70O6N4Mg

Chlorophyll a occurs in all types of plants and in algae.Chlorophyll b is found primarily in land plants. Chlorophyll


c1 and chlorophyll c2 are present in various types of algae.Chlorophyll d is found in red algae.

All forms of chlorophyll have a similar chemical struc-ture. They have a complex system of rings made of carbonand nitrogen known as a chlorin ring. The five forms of

Chlorophyll. Red atoms are oxygen;white atoms are hydrogen; carbonatoms are black; blue atoms are

nitrogen; and green atom ismagnesium. P U B L I S H E R S R E S O U R C E

G R O U P


CHLOROPHYLL

chlorophyll differ in the chemical groups attached to thechlorin ring. These differences result in slightly differentcolors of the five chlorophylls.

French chemists Pierre-Joseph Pelletier (1788–1842) andJoseph-Bienaime Caventou (1795–1877) first isolated chloro-phyll in 1817. In 1865, German botanist Julius von Sachs(1832–1897) demonstrated that chlorophyll is responsiblefor photosynthetic reactions that take place within the cellsof leaves. In the early 1900s, Russian chemist Mikhail Tsvett(1872–1920) developed a technique known as chromatogra-phy to separate different forms of chlorophyll from eachother. In 1929, the German chemist Hans Fischer (1881–1945) determined the complete molecular structure, makingpossible the first synthesis of the molecule in 1960 by theAmerican chemist Robert Burns Woodward (1917–1979).

HOW IT IS MADE

Plants make chlorophyll in their leaves using materialsthey have absorbed through their roots and leaves. Thesynthesis of chlorophyll requires several steps involving

Interesting Facts

• The chemical structure ofchlorophyll is very similarto that of hemoglobin, themolecule that transportsoxygen in the red bloodcells of mammals. The majordifference between the twois that hemoglobin containsan atom or iron at thecenter of a large ring com-pound, while chlorophyllhas an atom of magnesiumin the same location.

• Leaves contain compoundscalled carotenoids that are

red, orange, and yellow incolor. These colors aremasked by the green colorof chlorophyll. In fall,plants stop producingchlorophyll, and the red,orange, and yellow ofcarotenoids becomevisible. Carotenoids do notperform photosynthesis,although they do transmitlight energy to chlorophyll,where photosynthesistakes place.


CHLOROPHYLL

complex organic compounds. First, the plant converts a com-mon amino acid, glutamic acid (COOH(CH2)2CH(NH2)COOH)into an alternative form known as 5-aminolevulinic acid(ALA). Two molecules of ALA are then joined to form a ringcompound called porphobilinogen. Next, four molecules ofporphobilinogen are joined to form an even larger ring struc-ture with side chains. Oxidation of the larger ring structureintroduces double bonds in the molecule, giving it the abilityto absorb line energy. Finally, a magnesium atom is intro-duced into the center of the ring and side chains are added tothe ring to give it its final chlorophyll configuration.


Plants store chlorophyll in their chloroplasts, organelles(small structures) that carry out the steps involved in photo-synthesis. Each chloroplast contains many clusters of severalhundred chlorophyll molecules called photosynthetic units.When a photosynthetic unit absorbs light energy, chloro-phyll molecules move to a higher energy state, initiatingthe process of photosynthesis. The overall equation for theprocess of photosynthesis is 6CO2 + 6H2O ! C6H12O6 + 6O2.

That simple equation does not begin to suggest the com-plex nature of what happens during photosynthesis. Botanistsdivide that process into two major series of reactions: the lightreactions and the dark reactions. In the light reactions, plants

Words to Know

CHLORIN RING A ring of carbon and nitro-gen atoms bonded to each other.

CHROMATOGRAPHY Process by which amixture of substances passes through acolumn consisting of some material thatcauses the individual components in themixture to separate from each other.

PHOTOSYNTHESIS The process by whichgreen plants and some other organisms

using the energy in sunlight to convertcarbon dioxide and water into carbohy-drates and oxygen.



CHLOROPHYLL

use the energy obtained from sunlight to make two com-pounds, adenosine triphosphate (ATP) and nicotinamide ade-nine dinucleotide phosphate (NADPH). ATP and NADPH arenot themselves components of carbohydrates, the final pro-ducts of photosynthesis. Instead, they store energy that isused to make possible a series of thirteen different chemicalreactions that occur during the dark stage of photosynthesisthat result in the conversion of carbon dioxide and waterto the simple carbohydrate glucose (C6H12O6).


Attenborough, David. The Private Life of Plants. Princeton, NJ:Princeton University Press, 1995.

Buchanan, B. B., W. Gruissem, and R. L. Jones. Biochemistry andMolecular Biology of Plants. Rockville, MD: American Societyof Plant Physiologists, 2000.

‘‘Chlorophyll and Chlorophyllin.’’ The Linus Pauling InstituteMicronutrient Information Center.http://lpi.oregonstate.edu/infocenter/phytochemicals/chlorophylls/ (accessed on October 3, 2005).

May, Paul. ‘‘Chlorophyll.’’ School of Chemistry, University of Bristol.http://www.chm.bris.ac.uk/motm/chlorophyll/chlorophyll_h.htm (accessed on October 3, 2005).

Steer, James. ‘‘Structure and Reactions of Chlorophyll.’’http://www.ch.ic.ac.uk/local/projects/steer/chloro.htm (accessedon October 3, 2005).

See Also Carbon Dioxide; Water


CHLOROPHYLL


FORMULA:C27H45OH


oxygen

COMPOUND TYPE:Sterol

STATE:Solid




decomposes at about360�C (680�F)


in water; soluble inacetone, alcohol,

ether, benzene, andother organic

solvents.

Cholesterol

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OVERVIEW

Cholesterol (koh-LESS-ter-ol) is also known as cholesterin;cholest-5-3n-3b-ol; 5-cholestin-3-b-ol; 3b-hydroxy-5-cholestene;and 10,13-dimethyl-17-(6-methylheptan-2-yl)-2,3,4,7,8,9,11,12,14,15,16,17-dodecahydro-1H-cyclopenta[a]phenanthren-3-ol. It isa waxy white or pale yellow solid with virtually no taste orodor. It is present in the bodies of all higher animals,especially in the brain and spinal cord. Chemically, choles-terol is classified as a fat, a member of the lipid family.Fats are the product of the trihydric alcohol (alcohol withthree -OH groups) glycerol and a fatty acid. Fatty acids areorganic acids with many carbon atoms, usually eight ormore.

The first description of cholesterol was written by aFrench scientist by the name of Poulletier de la Salle (datesnot available), who isolated the compound from gallstones, arich source of the substance. In 1816, de la Salle’s compatriotMichel Eugene Chevreul (1786–1889) suggested the name ofcholesterine for cholesterol, combining the French words for

CH

H H

HH H

H

H HC

C CC C

CH

HH H

H

H

H

H

H HHH

H

H

C

HO

C

CH3C

C

C

CC

C

C

C

C

C

H3C

CH3

CH3

CH3

C

H

H

CC

H


bile (chole) and stone (stereos). More than a century passedbefore an accurate understanding of the chemical structureand behavior of cholesterol was attained. Finally, during the1910s, research by the German chemists Heinrich OttoWieland (1877–1957) and Adolf Winhaus (1876–1959) solvedmost of the fundamental problems about cholesterol, anaccomplishment for which the two men were awarded the

Cholesterol. Red atom isoxygen; white atoms are



CHOLESTEROL


1927 (Wieland) and the 1928 (Windhaus) Nobel Prizes inchemistry. All that remained was the determination of thestructural formula for cholesterol and the first synthesis ofthe compound, both achieved by the American chemistRobert Burns Woodward (1917–1979) in 1955.

HOW IT IS MADE

The primary source of cholesterol is the liver. Aftercholesterol is produced, the liver packages cholesterol mole-cules with proteins in units known as lipoproteins, which arethen distributed throughout the body by way of the blood-stream. Some cholesterol is deposited in cells, where it isused as the raw material in the synthesis of a number ofbiologically essential compounds, such as vitamin D3, ster-oids (such as estrogen and testosterone), and the bile acids,used by the body to digest foods. Excess cholesterol notneeded by cells remains in the bloodstream until it isreturned to the liver.

Commonly, the body produces more cholesterol than cellsneed. Or a person takes in cholesterol in his or her diet inexcess of that needed by the body. In such cases, cholesterolmay accumulate in the bloodstream and, at some point, bedeposited on the walls of blood vessels. As these depositsgrow larger, they may impeded the flow of blood, eventuallyleading to heart problems or stroke.

Interesting Facts

• The amount of cholesterolin a person’s body dependsessentially on two factors:genetics and diet. Theability of a person’s bodyto produce cholesterol isdetermined by his or hergenetic component. Somepeople simply make highlevels of cholesterol, and

other produce lower levels.Those levels can beaffected to some extentby the kinds and amountsof cholesterol-containingfoods (such as dairyproducts and organ meats)one includes in his or herdaily diet.


CHOLESTEROL

Lipoproteins produced in the liver take one of two forms.Low-density lipoproteins (LDL) carry cholesterol directly tocells. Because this cholesterol serves a useful biological func-tion, it is sometimes called ‘‘good’’ cholesterol. High-densitylipoproteins (HDL), by contrast, bypass cells and remain inthe blood stream. The cholesterol in HDL lipoproteins servesno useful function in the body and is often referred to as‘‘bad’’ cholesterol. The role of cholesterol in the human bodyand dietary methods of maintaining the correct HDL:LDLratio in the blood has been the subject of some controversyand considerable educational programs in recent decades.

A relatively small amount of cholesterol is used in mak-ing some drugs and cosmetics. The cholesterol required forthese commercial purposes is obtained from natural sources,primarily spinal fluid taken from cattle who have beendestroyed for meat products.


Cholesterol plays three primary roles in the human body.First, it helps the body digest fatty foods. During digestion,the liver converts cholesterol into a yellowish-green liquidcalled bile. Bile helps break down fatty foods into a form thatcan be absorbed by the body. Second, cholesterol is a precur-sor to a number of important hormones, including androgen,estrogen, progesterone, and testosterone. Third, cholesterolis also a precursor to vitamin D, which has a number ofessential functions, including the maintenance of healthy

Words to Know

FAT An ester formed in the reaction betweenglycerol (C3H5(OH)3) and a fatty acid, anorganic acid with more than eight carbonatoms.

LIPIDS Organic compounds that are insolublein water, but soluble in most organicsolvents, such as alcohol, ether, and acetone.

PRECURSOR A compound that gives rise tosome other compound in a series ofreactions.

STEROL Organic compound containing oneor more ring systems and a hydroxy(-OH) group

CHOLESTEROL


bones and nervous system, proper growth, muscle tone, pro-duction of insulin, normal reproductive functions, and properimmune system function.


‘‘Cholesterol.’’ Chemical Land 21.http://www.chemicalland21.com/arokorhi/lifescience/phar/CHOLESTEROL.htm (accessed on October 3, 2005).

‘‘Cholesterol.’’ Medline Plus.http://www.nlm.nih.gov/medlineplus/cholesterol.html (accessedon October 3, 2005).

‘‘Cholesterol, Other Lipids, and Lipoproteins.’’ In In Depth Report.Edited by Julia Goldrosen. Atlanta: A.D.A.M., 2004.

Goldstein, Joseph P., and Michael S. Brown. ‘‘Cholesterol: A Centuryof Research.’’ HHMI Bulletin, 2003.http://www.hhmi.org/bulletin/sept2003/cholesterol/century.html(accessed on October 3, 2005).

‘‘The Nobel Prize in Physiology or Medicine 1985.’’ Nobelprize.org.http://nobelprize.org/medicine/laureates/1985/press.html(accessed on October 3, 2005).

‘‘The Overall Synthesis of Cholesterol.’’ Synthesis of Cholesterolhttp://www.chm.bris.ac.uk/webprojects2000/ahester/synthchol.html (accessed on October 3, 2005).


CHOLESTEROL


FORMULA:C6H5CH=CHCHO


oxygen

COMPOUND TYPE:Aromatic aldehyde

(organic)

STATE:Liquid


MELTING POINT:�7.5�C (18�F)



in water; soluble inalcohol, ether, and

chloroform

Cinnamaldehyde

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OVERVIEW

Cinnamaldehyde (sin-uh-MAL-duh-hide) is also known ascinnamic aldehyde; 3-phenyl-2-propenal; cinnamyl aldehyde;phenylalacrolein; cinnamal; and trans-cinnamaldehyde. It is ayellowish oily, liquid with a sweet taste and a cinnamish odorresponsible for the characteristic taste and odor of cinnamonspice. It occurs naturally in the bark of the cinnamon tree,Cinnamomum zeylanicum, which is native to Sri Lanka andIndia, and has been cultivated in other parts of the world,such as Brazil, Jamaica, and Mauritius. Cinnamaldehyde isalso found in other members of the the Cinnamomum spe-cies, including cassia and camphor.

The molecular formula for cinnamaldehyde was deter-mined in 1834 by the French chemists Jean Baptiste AndreDumas (1800–1884) and Eugene Melchior Peligot (1811–1890),although its structural formula was deciphered only in 1866by the German chemist Emil Erlenmeyer (1825–1909).

Primary uses for Cinnamaldehyde are as a food flavoringand a medical herb. It has been used for many centuries to

C C NC

CC

O

H H

H

H

H

H

C C

C C

CH3

CH3

H


treat a wide variety of disorders, ranging from the commoncold and the flu to diarrhea to cancer. It was mentioned inChinese medical texts as early as 2700 BCE and was describedin a famous Chinese medical text, the Tang Materia Medica,written in 659 CE It has also been used for centuries inAyurvedic medicine, the ancient healing art of India.

HOW IT IS MADE

Cinnamaldehyde is prepared commercially by treatingthe bark of the Cinnamomum zeylanicum tree with steam.The aldehyde dissolves in the steam and can then be

Cinnamaldehyde. Red atom isoxygen; white atoms are

hydrogen; black atoms arecarbon; and blue atom is

nitrogen. Gray sticks showdouble bonds; Striped sticks

show a benzene ring.P U B L I S H E R S R E S O U R C E

G R O U P


CINNAMALDEHYDE

extracted as the steam cools and condenses to form cold water,in which the compound is much less soluble. Cinnamaldehydecan also be synthesized by reacting benzaldehyde (C6H5CHO)with acetaldehyde (CH3CHO). The two compounds condensewith the elimination of water to form cinnamaldhyde.


In addition to its uses as a herbal remedy, the primary useof cinnamaldehyde is as a food additive to enhance the flavorand/or odor of food products. It is used most commonly in cakemixes, chewing gums, chocolate products, synthetic cinnamonoils, cola drinks, ice creams, soft drinks, and vermouth. Thecompound is also added to a number of cosmetics and homecare products to improve their odor. Such products includedeodorants, detergents, mouthwashes, perfumes, sanitary nap-kins, soaps, and toothpastes. Finally, cinnamaldehyde is usedto some extent in agriculture as an insecticide and fungicide.

No safety concerns about the use of cinnamaldehyde asan herbal remedy, food additive, or pesticide has beenexpressed. The U.S. Food and Drug Administration (FDA)has classified the compound as a generally-recognized as safe(GRAS) food additive, permitting its continued use as a foodadditive in the United States.

Interesting Facts

• Cinnamaldehyde is acomponent of sprays

used as cat and dog repel-lents.

Words to Know

AROMATIC COMPOUND A compound whosechemical structure is based on that ofbenzene (C6H6).



CINNAMALDEHYDE


‘‘Cinnamaldehyde.’’ Chemical Land 21.http://www.chemicalland21.com/arokorhi/specialtychem/perchem/CINNAMALDEHYDE.htm (accessed on October 3,2005).

‘‘Cinnamaldehyde (040506) Fact Sheet.’’ U.S. Environmental Protection Agency.http://www.epa.gov/pesticides/biopesticides/ingredients/factsheets/factsheet_040506.htm (accessed on October 3, 2005).

‘‘Oleum Cinnamomi (U. S. P.) Oil of Cinnamon.’’ King’s AmericanDispensatory (1898).http://www.ibiblio.org/herbmed/eclectic/kings/cinnamomum_oleu.html (accessed on October 3, 2005).


CINNAMALDEHYDE


FORMULA:HOOCCH2C(OH)

(COOH)CH2COOH


oxygen


(organic)

STATE:Solid






alcohol, ether, andother organic

solvents

Citric Acid

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OVERVIEW

Citric acid (SIT-rik AS-id) is also known as 2-hydroxy-1,2,3-propanetricarboxylic acid and b-hydroxytricarballylicacid. It is a common constituent of plant and animal tissues.Its presence is especially noticeable in citrus fruits, such aslemons, limes, oranges, tangerines, grapefruits, and kum-quat, which get their name from the acid. In pure form, citricacid is a colorless, translucent, odorless crystalline or pow-dery material with a pleasantly acidic taste. It frequentlyoccurs as the monohydrate, with a single molecule of waterassociated with each citric acid molecule. The formula for themonohydrate is HOOCCH2C(OH)(COOH)CH2COOH�H2O. Themonohydrate is efflorescent, meaning that it tends to loseits water of hydration when exposed to the air.

Citric acid plays an important role in metabolism, theset of chemical reactions that occur when cells break downfats, carbohydrates, and other compounds to produce energyand compounds needed to build new cells and tissues. Infact, the series of reactions by which carbohydrates are

O

COH

OHO

HC

OH

C

HO

O H

H

C

CH

C


converted to energy is generally known as the citric acidcycle because of the fundamental role played by the com-pound in those reactions. The citric acid cycle is also knownas the Krebs cycle, after the German-British biochemist SirHans Adolf Krebs (1900–1981), who discovered the series ofreactions in 1937. Citric acid also acts as an antioxidant, asubstance that rid the body of molecules called free radicalsthat can damage healthy cells, promote cancer, and bringabout ageing.

The discovery of citric acid is often credited to the Arabalchemist Jabir Ibn Hayyan (721–815), also known by his

Citric acid. Red atomsare oxygen; white atoms arehydrogen; and black atoms



CITRIC ACID


Latin name of Geber. Geber described a substance with all theproperties that we equate with citric acid today, but he knewnothing about its chemical structure. The first person toisolate the compound as a pure substance was the Swedishchemist Karl Wilhelm Scheele (1742–1786), who obtainedcitric acid from the juice of lemons. By the mid-nineteenthcentury, citric acid was being produced commercially in Italyfrom lemons and other citrus fruits.

An important step in the commercial manufacture ofcitric acid occurred in 1892 when the German microbiolo-gist Carl Wehmer (dates not available) found that citric acidcould be produced by the penicillin mold. Wehmer’s discov-ery paved the way for large-scale industrial production ofcitric acid. In 1917, the American chemist James Currie(dates not available) made another important breakthroughin the synthesis of citric acid. While studying the processof fermentation in cheese making, he discovered that themold Aspergillus niger is able to convert sugar to citricacid. After Currie joined the pharmaceutical companyPfizerin 1917, he developed a process called SUCIAC—sugarunder conversion into citric acid—by which the compoundcould be made in mass quantities. That process eventuallybecame the primary method by which citric acid is pro-duced today.

HOW IT IS MADE

At one time, citric acid was obtained primarily fromcitrus fruits, such as lemons and limes. Today, it is producedsynthetically using the Aspergillus niger mold, as describedabove. The citric acid produced in this reaction is purified bycrystallization. The anhydrous form crystallizes from hotwater, and the monohydrate form from cold water.

Interesting Facts

• The addition of citric acidto candy gives the

product a ‘‘super sour’’taste.


CITRIC ACID


Citric acid is added to foods, drinks, and medicinesto make them more acidic. Increasing the acidity of theseproducts not only gives them a tart taste, but also preventsthe growth of bacteria. Citric acid is also used to preserve theflavors of canned fruits and vegetables and to maintain theproper acidic level of jams and jellies that will help them gel.

In addition to its use as a food additive, citric acid has anumber of other commercial and industrial applications,including the following:

• As a sequestering agent to remove small amounts ofmetals in a solution. A sequestering agent is a substancethat surrounds and captures some other substance (suchas metals) and removes them from a solution;

• In the cleaning and polishing of stainless steel andother metals;


• In the production of certain kinds of polymers;

• For the removal of sulfur dioxide from the waste gasesproduced at smelters; and

• As a builder in detergents, a substance that increasesthe detergent’s cleaning efficiency, usually by maintaining

Words to Know


FERMENTATION Chemical process by whichyeasts or molds break down sugar intoalcohol and carbon dioxide.

METABOLISM Process including all of thechemical reactions that occur in cells bywhich fats, carbohydrates, and other com-pounds are broken down to produce

energy and the compounds needed tobuild new cells and tissues.

MORDANT Substance used in dyeing andprinting that reacts chemically with both adye and the material being dyed to helphold the dye permanently to the material.

POLYMER Compound consisting of verylarge molecules made of one or two smallrepeated units called monomers.

CITRIC ACID


the proper acidity or softening the water in which thedetergent acts.


‘‘Citric Acid.’’ Jungbunzlauer.http://www.jungbunzlauer.com/products/product_1.html(accessed on October 3, 2005).

‘‘Citric Acid, Anhydrous.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/c4735.htm(accessed on October 3, 2005).

Kuntz, Lynn A. ‘‘Acid Basics.’’ Food Product Design (May 1993).Also available online athttp://www.foodproductdesign.com/toolbar_library.html(accessed on October 3, 2005).


CITRIC ACID

OTHER NAMES:Not applicable

FORMULA:Not applicable


oxygen, nitrogen


STATE:Solid

MOLECULAR WEIGHT:100,000 to 150,000

g/mol



SOLUBILITY:Not applicable

Collagen

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OVERVIEW

Collagen (KO-lah-jen) is the most abundant protein in theanimal kingdom. Approximately one third of the protein in amammal’s body is collagen. It makes up a major portion of theconnective tissue found in skin, joints, ligaments, muscles, ten-dons, and bones. Different types of collagen occur in differentspecies. That is, the collagen found in humans is somewhat dif-ferent from that found in cows, and both human and cow collagendiffer from the collagen found in other animals, such as dogs andats. Nonetheless, all forms of collagen have a common molecularstructure that consists of three rope-like strands intertwinedwith each other. Each strand (called tropocollagen) is a polymerconsisting of amino acids, the most common of which are glycine,proline, and hydroxyproline. Collagens differ from each other inregard to the relative amounts of each amino acid present.

HOW IT IS MADE

Collagen is synthesized in the bodies of all higher verte-brates in a complex series of reactions that begin with the


linking of amino acids with each other. Amino acids areorganic compounds that contain both the carboxyl group(-COOH) and the amino group (-NH2). The amino acids arejoined to each other in very long chains known as polypep-tides (a word meaning ‘‘many amino acids’’). After assembly,polypeptide chains intertwine with each other in groupsof three to make large molecules called procollagen (‘‘earlycollagen’’), which is then cut into smaller pieces by enzymesdesigned especially for that purpose. The three strands thatmake up each collagen group are held together by the actionof vitamin C molecules.


All of the connective tissue in the body contains col-lagen. This collagen is flexible but not stretchy and will tearif pulled to strongly. Collagen is also a primary component ofcartilage, the material that fills the gaps between bones andfills out structures that are firm but somewhat soft, such asthe end of the nose and ears. There are at least a dozen typesof collagen in the body, each one with a slightly differentphysical and chemical structure.

Type I is the most abundant kind of collagen. It formslong strands that criss-cross the spaces between cells and isfound throughout the body, particularly in tendons, bones,and scars. Type II collagen is found in cartilage, and Type IIIcollagen in granulation tissue that forms when woundsheal. Type IV collagen comprises the basal lumina, the mem-brane that supports skin and internal surfaces. The eightother types of collagen all have their specific functions inthe body.

Plastic surgeons use collagen to fill wrinkles and lines intheir patients’ faces and bodies. As people age, the tissue thatfills out their faces and makes the skin look smooth andtight breaks down, leaving lines and wrinkles. Injecting col-lagen into wrinkles fills the area under the skin with tissuethat puffs out the skin, making it firm and smooth again.Doctors also use collagen to fill in scars. In most cases,collagen treatments are not permanent. The collagen breaksdown or is absorbed and additional treatments are necessaryto remove wrinkles.


COLLAGEN

Several health disorders result from inadequate or abnor-mal collagen in the body. Scurvy, caused by a deficiency ofvitamin C, is the best known of these. When adequateamounts of vitamin C are not present in the body, collagenmolecules break apart and muscles and joints are damaged.Ehlers-Danlos syndrome is a disorder that occurs when col-lagen molecules are weakened, causing bruising of the skin,rupture of arteries or intestines, overly flexible joints, skinand bone deformities, and hip dislocations. Osteogenesisimperfecta results in poorly formed bones and causes thesclera (the white part of the eye) to turn blue.

Interesting Facts

• When collagen is treatedwith boiling water, it isconverted to gelatin, awidely used householdproduct. Popular dessertssuch as Jell-O� are madefrom collagen taken fromthe hooves, bones, andconnective tissue of cowsand pigs.

• In the cooking methodknown as ‘‘braising’’, meats

are heated for a long timeover low heat. Duringbraising, collagen mole-cules ‘‘melt’’ (break apart)producing a tender meatyproduct in a rich broththat turns to gelatin as itcools. By contrast, cookingmeat over high heatcauses proteins to shrinkand become tougher.

Words to Know


POLYPEPTIDE A molecule composed ofmany amino acids in a chain.


COLLAGEN


‘‘Collagenase and Collagen: What Is Collagen?’’ BioSpecifics Technologies Corporation.http://www.biospecifics.com/collagendefined.html (accessedon December 6, 2005).

‘‘Collagens.’’ Kimball’s Biology Pages.http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Collagens.html (accessed on December 6, 2005).

Goodsell, David S. ‘‘Collagen: Your Most Plentiful Protein.’’ ProteinData Bank.http://www.rcsb.org/pdb/molecules/pdb4_1.html (accessed onDecember 6, 2005).


COLLAGEN


FORMULA:Cu2O

ELEMENTS:Copper, oxygen


STATE:Solid



BOILING POINT:Decomposes at

1800�C (3300�F)


soluble in inorganicacids, such as hydro-chloric, sulfuric, and

nitric acids

Copper(I) Oxide

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OVERVIEW

Copper(I) oxide (KOPP-er one OK-side) is also known ascuprous oxide, red copper oxide, copper protoxide, copper hemi-oxide, and copper suboxide. It is a yellowish, red, or brown crystal-line substance, depending on its method of preparation. It doesnot burn and is stable in dry air. In moist air, it slowly changes tocopper(II) oxide (CuO). The compound has been used by humansfor thousands of years, first as a pigment in glazes, and later infungicides, electronic components, and industrial reactions.

In 1883, copper(I) oxide was the first substance found tohave semiconducting properties. A semiconductor conductsan electric current, although not nearly as efficiently as aconductor like copper, gold, or silver. Semiconductor compo-nents are now widely used in computer chips, although theyare now made from silicon rather than copper(I) oxide.

HOW IT IS MADE

Copper(I) oxide occurs naturally as the mineral cuprite. Itforms when native copper (copper as an element) is exposed

Cu

Cu

O


to the air, although the process occurs very slowly. Copper(I)oxide can also be made synthetically by exposing coppermetal to a high concentration of oxygen at an elevatedtemperature. Care must be taken, however to prevent thecopper from oxidizing completely to form copper(II) oxide.A number of other industrial methods are also available forthe synthesis of copper(I) oxide. For example, electrolysis ofa solution of sodium chloride using copper electrodes resultsin the formation of copper(I) oxide.


Copper(I) oxide is used as a pigment in porcelain glazesand stained glass. In opaque glass, it provides a bright brick-red color if large enough crystals are used. Smaller crystalsgive a yellowish color. The use of copper(I) oxide as a pig-ment in glazes dates back to the time of ancient Egypt.

Many antifouling marine paints contain copper(I) oxide.Antifouling paints are paints that prevent the formation ofbarnacles and other organisms on the bottom of a boat. Thecompound is also used as an antifungal agent, a substancethat kills mildew, rust, and other types of fungus. Fungi-cides based on copper(I) oxide are commonly used on avariety of crops susceptible to attack by such organisms.Copper(I) oxide acts by inhibiting the growth of fungalspores (from which new plants develop) rather than killingmature fungi.

Copper(I) oxide is used in photoelectric cells, which arecells that generate an electric current when exposed to light.

Copper(I) oxide. Red atom isoxygen and turquoise atoms

are copper. P U B L I S H E R S



COPPER(I) OXIDE

Photoelectric materials are usually semiconductors. Copper(I)oxide photoelectric cells do not generate much power, butthey react rapidly to changes in light levels. This propertymakes them useful as light detectors, which have manyapplications from cameras with automatic adjustment set-tings to automatic door openers and burglar alarms.

In the 1980s, a ceramic form of copper(I) oxide was foundto have superconducting properties at temperatures higherthan previously known superconductors. Superconductorshave the ability to carry an electric current virtually withoutresistance. Once a current is initiated in a superconductor, itcontinues to travel through the material essentially forever.Superconductor research may lead to new technologies, fromcheaper electrical power to magnetically levitated high-speedtrains.

Exposure to moderate amounts of copper(I) oxide can beirritating to the skin, eyes, and respiratory system. If heated,it gives off copper fumes that can cause symptoms similar tothe common cold and may discolor the skin and hair. Ifswallowed, copper(I) oxide has a metallic taste and mayinduce vomiting, nausea, and stomach pain. In the mostsevere cases, copper(I) oxide may cause black or tarry stools,jaundice, and bloody vomiting, with long-term damage to theliver. In the environment, copper(I) oxide is very toxic to fishand crustaceans.

Interesting Facts

• Copper metal is sometimesused for roofing onnotable buildings, suchas art museums or statecapitols. Over time, thecopper metal develops apatina, a thin layer of colorthat adds to the eleganceof the roof. The patinaconsists primarily ofcopper(I) oxide.

• In 1904, the Germanphysicist WilhelmHallwachs (1859–1922)discovered that acombination of coppermetal and copper(I) oxidedisplays the photoelectriceffect, in which a beam oflight causes electricity toflow through a material.


COPPER(I) OXIDE


‘‘Cuprite.’’ Dale Minerals International.http://www.webmineral.com/data/Cuprite.shtml (accessed onOctober 3, 2005).

‘‘Cuprous oxide.’’ Hummel Croton, Inc.http://www.hummelcroton.com/msds/cu2o_m.html (accessedon October 3, 2005).

Patnaik, Pradyot. Handbook of Inorganic Chemicals. New York:McGraw Hil, 2003, 271 273.

Richardson, H. W., ed. Handbook of Copper Compounds and Appli

cations. New York: Marcel Dekker, 1997.

See Also Copper(II) Oxide

Words to know

ELECTROLYSIS Process in which an electriccurrent is used to bring about chemicalchanges.

OXIDIZE To combine with oxygen.

PHOTOELECTRIC CELL A device that gener-ates electricity when exposed to light.

SEMICONDUCTOR A substance that allowselectricity to flow through it at a lesser

rate than a conductor, though more thana non-conductive substance.

SUPERCONDUCTOR A substance thatallows electricity to flow through it withvery little resistance.



COPPER(I) OXIDE

OTHER NAMES:Cupric oxide; coppermonoxide; black cop-

per oxide

FORMULA:CuO

ELEMENTS:Copper, oxygen


STATE:Solid




decomposes


organic solvents;soluble in dilute acids

and ammoniumhydroxide

Copper(II) Oxide

KE

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OVERVIEW

Copper(II) oxide (KOPP-er two OK-side) occurs in nature inthe minerals tenorite, melaconite, and paramelaconite. In pureform, it is a black to brownish powder or crystalline material.Like copper(I) oxide, copper(II) oxide is a semiconductor, amaterial that conducts an electric current, although not nearlyas well as conductors such as gold, silver, and aluminum.

HOW IT IS MADE

Copper(II) oxide forms naturally in the Earth as a result ofthe weathering of copper sulfides (Cu2S and CuS). It is pre-pared synthetically by heating copper metal in air to about800�C (1,500�F) or, more commonly, by heating copper(II)carbonate (CuCO3) or copper(II) nitrate [Cu(NO3)2] to red heat.


Throughout recorded history, copper(II) oxide has beenused as a pigment to color ceramics, enamels, porcelain

Cu

O


glazes, and artificial gems, applications that continue to thepresent day. The oxide adds a bluish to greenish tint to suchmaterials. Copper(II) oxide also finds use as an insecticideand fumigant. It is used primarily in the treatment of potatoplants and as an antifouling agent on boat hulls. An antifoul-ing agent is a material that prevents the formation of bar-nacles and other organisms on the bottom of a boat. Whensuch organisms grow on a boat’s hull, they increase thefriction produced when the boat rides through the water,thus reducing its speed. The compound is also used as a woodpreservative, to protect fence posts, pilings, decking, roofing,shingles, sea walls, and other freshwater and marine struc-tures from insects and fungi.

Other uses to which copper(II) oxide is put including thefollowing:

• In the preparation of superconducting materials, mate-rials that have essentially no resistance to the flow ofan electric current;

• In the manufacture of batteries and electrodes;

• As a welding flux for use with bronze objects and mate-rials;

• For polishing of optical glass, glass used in telescopes,microscopes, and similar instruments;

• In the preparation of phosphors, materials that glow inthe dark after being exposed to light;

Copper(II) oxide. Red atom isoxygen and turquoise atom is

copper. P U B L I S H E R S R E S O U R C E

G R O U P


COPPER(II) OXIDE

• For the removal of sulfur and sulfur compounds forpetroleum;

• In the manufacture of rayon; and

• As a catalyst in many industrial and commercial chemi-cal reactions.

Inhaling copper(II) oxide fumes may result in a conditionknown as metal fume fever, with irritation of the throat,coughing, shortness of breath, nausea, and fever. Excessiveexposure may result in chronic lung disease. Ingesting largeamounts of copper(II) oxide may cause vomiting, diarrhea,nausea, excessive salivation, and intense abdominal pain.The compound is also an eye irritant.

Interesting Facts

• The ancient Greeks used amixture of copper(II) oxideand copper(II) sulfate totreat wounds.

• U.S. pennies sometimesdevelop a black coatingthat is caused by copper(II)oxide. The coating can beremoved by cleaning thepenny in a solution of

vinegar, lemon juice, andsalt. Coca ColaTM can also beused because it containsphosphoric acid (H3PO4),which dissolves copper(II)oxide.

• Some fingerprinting pow-ders contain copper(II)oxide.

Words to Know

CATALYST A material that increases therate of a chemical reaction withoutundergoing any change in its own chemicalstructure.

FLUX A material that lowers the meltingpoint of another substance or mixtureof substances or that is used in cleaninga metal.


COPPER(II) OXIDE


‘‘Copper Oxide 99.99+%.’’ Louisiana State University.http://www.camd.lsu.edu/msds/c/copperII_oxide.htm#Synonyms(accessed on October 5, 2005).

‘‘Cupric Oxide.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/c5885.htm(accessed on October 5, 2005).

Richardson, H. W., ed. Handbook of Copper Compounds and Appli

cations. New York: Marcel Dekker, 1997.


COPPER(II) OXIDE

OTHER NAMES:Cupric sulfate; blue

vitriol; blue stone;blue copperas

FORMULA:CuSO4

ELEMENTS:Copper, sulfur,

oxygen


STATE:Solid



decomposes above560�C (1,040�F)


SOLUBILITY:Very soluble in water;moderately soluble in

methyl alcohol;slightly soluble in

ethyl alcohol

Copper(II) Sulfate

KE

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TS

OVERVIEW

Copper(II) sulfate (KOPP-er two SUL-fate) is a white crys-talline powder in its anhydrous state, although it occurs mostcommonly as the pentahydrate, CuSO4�5H2O, which is a bluegranular crystalline solid. When the pentahydrate is heated,it loses its water of hydration and returns to its white,powdery anhydrous state. The transition between its whiteanhydrous form and its blue hydrated form is sometimesused in devices and toys that indicate the presence orabsence of moisture in the air.

Copper(II) sulfate is probably the most important andmost widely used of all copper compounds. It is used inagriculture, the paints and covering industry, in electricalapplications, in the production of other chemicals, and inother industrial and commercial applications.

HOW IT IS MADE

Copper(II) sulfate occurs in nature as the mineral cal-canthite. Calcanthite is somewhat rare since copper(II)

SO

OO-

O-

Cu++


sulfate dissolves readily in water, and therefore the mineralcan leach out of rock by groundwater. The compound is madein the laboratory and commercially by treating copper metalor one of the copper oxides (CuO or Cu2O) with sulfuric acid(H2SO4).


Copper(II) sulfate is used extensively in agriculture as asoil additive, a fumigant for trees, a feed additive to preventmineral deficiencies, and as a wood preservative. It is acomponent, along with calcium oxide (CaO; quicklime), ofone of the oldest and most popular plant fumigants, a mate-rial called Bordeaux mixture. Many of copper(II) sulfate’suses depend on his highly toxic character. It is used toprevent the growth of mold and mildew; to sanitize surfacesin hospitals; to kill algae in swimming pools, reservoirs, andother bodies of water; as an herbicide to kill weeds; and as agermicide, to prevent the growth of unwanted seeds.Although very effective in such applications, copper(II) isoften not the first choice because it may have toxic effectson other plants and animals in the environment and onhumans.

Copper(II) sulfate

pentahydrate. Red atoms areoxygen; yellow atom is sulfur;and turquoise atom is copper.Gray sticks are double bonds.



COPPER(II) SULFATE

Some additional uses of copper(II) sulfate include thefollowing:

• As a mordant in the textile industry;

• In the production of blue pigments for paints, varnishes,glazes, dyes, inks, and other coloring materials;

• In electroplating, where it supplies the copper withwhich other metals are plated;

• In making lithographic prints and engravings;

• In the preservation and tanning of animal hides;

• As a catalyst in the refining of petroleum;

• As a nutritional supplement to treat copper deficiencydisorders;

• In the manufacture of fireworks, where it imparts ablue color to the display; and

• In the production of water-resistant adhesives for wood.

Copper(II) sulfate is known to be toxic to humans andother animals if ingested. It may cause burning in the mouthand stomach, nausea, vomiting, abdominal pain, diarrhea,and a metallic taste in the mouth. It can cause gastrointest-inal bleeding and, if not eliminated from the body, can resultin kidney and liver damage, depression of the nervous sys-tem, paralysis, coma, and death from shock or kidney failure.Prolonged exposure to copper(II) sulfate dust can cause dis-coloration of the skin, damage to the blood and liver, andirritation of the eyes and nose. Copper(II) sulfate poses somerisk to the environment, both because of its toxic nature andbecause it does not break down readily.

Interesting Facts

• Copper(II) sulfate gets thename blue vitriol from thecolor of the pentahydrate(blue) plus the fact that it

is made from sulfuric acid,which is also called oil ofvitriol.


COPPER(II) SULFATE


‘‘Cupric Sulfate.’’ New Jersey Department of Health and SeniorServices.http://www.state.nj.us/health/eoh/rtkweb/0549.pdf(accessed on October 5, 2005).

‘‘Cupric Sulfate Anhydrous.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/c5920.htm(accessed on October 5, 2005).

Ware, George W. The Pesticide Book. Batavia, Ill.: Mesiter, 1999.

Young, Jay A. ‘‘Copper (II) Sulfate Pentahydrate.’’ Journal of

Chemical Education (February 2002): 158.

See Also Copper(II) Oxide

Words to Know

ANHYDROUS Form of a compound that lackswater.


FUMIGANT A pesticide that is applied as a gas.



COPPER(II) SULFATE

OTHER NAMES:Isopropylbenzene;

1-(methylethyl)benzene

FORMULA:C6H5CH(CH3)2


COMPOUND TYPE:Aromatic


STATE:Liquid





miscible with ethylalcohol, benzene,

ether, acetone, andmost organic

solvents

Cumene

KE

YF

AC

TS

OVERVIEW

Cumene (KYOO-meen) is a colorless, flammable liquidwith a penetrating gasoline-like odor. Chemically, it is classi-fied as an aromatic hydrocarbon. Aromatic hydrocarbons arecompounds of carbon and hydrogen with a molecular struc-ture based on that of benzene. Although cumene is probablynot well known to the average person, it is a very importantindustrial chemical. In 2004, some 3.74 million metric tons(4.12 million short tons) of cumene were produced in theUnited States, making it the twentieth most important che-mical made in that year by weight. Cumene is used primarilyas a raw material in the synthesis of other organic com-pounds, such as phenol, acetone, acetophenone, and methylstyrene, and as a thinner for paints and lacquers.

HOW IT IS MADE

Cumene is made in a straight-forward chemical reactionbetween benzene (C6H6) and propene (propylene; CH3CH=CH2).

C CH H

CC C

CCH H

H H

H

C

N

H

H

H

H

H


It can also be extracted from petroleum or from coal tar,the thick black material left after soft coal is convertedto coke.


Small amounts of cumene are used as thinners for paints,lacquers, and enamels, and as solvents in paints and othertypes of coatings. By far the greatest amount of cumene,however, is used as a raw material in the manufacture ofphenol, acetone, and methyl styrene. These compounds, inturn, have a great many chemical and industrial uses. Someof the most important uses are the production of plastics,such as polystyrene, phenol-formaldehyde resins, and poly-carbonates.

Cumene is a skin, eye, and respiratory system irritant.If inhaled, it can cause coughing, dizziness, drowsiness,

Cumene. Black atoms arecarbon; white atoms

are hydrogen. Bonds in thebenzene ring are representedby the double striped sticks.

White sticks show singlebonds. P U B L I S H E R S



CUMENE

sore throat, headache, and loss of muscular coordination.In large doses, it has a narcotic effect, resulting in drowsi-ness and insensitivity to pain and other stimuli, and maylead to unconsciousness. There is no evidence that cumeneis carcinogenic or that it causes hereditary damage to aperson or to offspring of individuals exposed to the com-pound.

Interesting Facts

• Traditionally, thesynthesis of cumenehas involved the use ofphosphoric acid (H3PO4)as a catalyst. That processresults in the release ofharmful by-products intothe environment, and anew process that uses

zeolites as a catalyst hasnow become more popular.Zeolites are a naturallyoccurring, earthy materialthat can be as effectiveas phosphoric acid inpromoting the synthesisof cumene.

Words to Know

AROMATIC HYDROCARBON A compound ofcarbon and hydrogen with a molecularstructure based on that of benzene.



SOLVENT A substance that is able todissolve one or more other substances.



CUMENE


‘‘Cumene.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/cicads/cicads/cicad18.htm#PartNumber:1 (accessed on December 22, 2005).

‘‘Cumene.’’ Technology Transfer Network, Air Toxics Websitehttp://www.epa.gov/ttn/atw/hlthef/cumene.html (accessed onDecember 22, 2005).

‘‘Cumene (1 methylethylbenzene).’’ Australian Government. Department of the Environment and Heritage.http://www.npi.gov.au/database/substance info/profiles/28.html(accessed on December 22, 2005).

See Also Acetone; Phenol; Styrene


CUMENE

OTHER NAMES:See Overview; data

below are for themethyl ester.

FORMULA:CH2=C(CN)COOCH3


oxygen, nitrogen

COMPOUND TTYPE:Ester (organic)

STATE:Liquid


MELTING POINT:�22�C (�7.6�F)


SOLUBILITY:Reacts with water;soluble in acetone,toluene, methylenechloride, and some

other organicsolvents

Cyanoacrylate

KE

YF

AC

TS

OVERVIEW

Cyanoacrylate (sye-AN-oh-ACL-ri-late) is a general termused to describe a family of esters derived in the reactionbetween cyanoacrylic acid and various alcohols, such asmethanol (methyl-2-cyanoacrylate) and ethanol (ethyl-2-cyanoacrylate). Cyanoacrylates are all esters of cyanoacrylicacid, CH2=C(CN)COOH, and include methyl-2-cyanoacrylate,ethyl-2-cyanoacrylate, and 2-octyl cyanoacrylate. The mate-rial is the primary ingredient in Super GlueTM, Krazy GlueTM,DuroTM, Quick GelTM, and a number of other products usedto glue two surfaces together with a very strong bond in amatter of seconds. The bonding activity of the cyanoacrylatesoccurs when the esters react with water to form polymersthat bond to materials with which they come into contact.The polymerization reaction occurs very quickly, resultingin strong bonds that form almost instantaneously.

Cyanoacrylate was discovered in 1942 by Americanresearchers Harry Coover (1919– ) and Fred Joiner, employeesof the Eastman Kodak Laboratories, in Rochester, New York.

C C

O

C

H N

H

CH3

C O


Coover and Joiner were attempting to synthesize a clearplastic material that could be used for gun sights. Instead,they obtained a liquid with a tendency to stick tightly toanything with which it came into contact. They decided thatthe product—then known as Eastman 910—was more of aproblem than an asset and set it aside for six years beforedeciding to explore its adhesive properties.

At that point, Eastman Kodak began studying the possi-bilities of using cyanoacrylate for military applications, spe-cifically for sealing wounds. It applied to the U.S. Food andDrug Administration (FDA) for permission to market theproduct for this use, an application that was approved in1964. Shortly thereafter, military physicians tested cyanoa-crylate glues in Vietnam and found them highly effective insealing the wounds of soldiers. In a spray form, the gluestopped bleeding from chest wounds long enough to allow

Cyanoacrylate. Red atomsare oxygen; white atoms arehydrogen; black atoms arecarbon; and blue atom is

nitrogen. Gray sticks indicatedouble bonds. P U B L I S H E R S



CYANOACRYLATE

wounded soldiers to reach a hospital. Although the use ofcyanoacrylates by the military proved to be a success, theFDA declined to approve the product for civilian use. Theproduct had a tendency to irritate the skin when it reactedwith moisture on the skin, releasing formaldehyde andcyanoacetate, both toxic substances. Eventually, researchshowed that the octyl ester, 2-octyl-cyanoacrylate, proved toform stronger bonds, was more flexible, and was less irritatingthan the methyl and ethyl esters used in the original Eastman610 formulation. With this change, the FDA approved theuse of 2-octyl-cyanoacrylate for use in closing wounds andincisions. In 2001, the FDA extended this approval to includeuse of the compound as an antibacterial agent.

HOW IT IS MADE

Cyanoacrylates are made by reacting cyanoacrylic acidwith an alcohol, such as methanol, ethanol, or 2-octanol, toform the corresponding ester.


Cyanoacrylates are still used in a variety of medicalapplications to close wounds and to protect wounds frominfection. The 2-octyl ester is used for this purpose becauseit has fewer hazardous side effects than do the methyl andethyl esters. Cyanoacrylate is preferred to stitches for clos-ing wounds because it is less likely to become infected andtends to leave fewer scars. For this reason, the compound isoften used for cuts on the face, although it cannot be used inthe nose or mouth. Consumers can buy cyanoacrylate productssuch as BandAid brand Liquid BandageTM for home use.

Cyanoacrylates are sometimes used in dental procedures.Their ability to bond tightly and quickly, to seal wounds, andto prevent the development of infections make them usefulfor a number of surgical procedures involving teeth andgums. The primary concern is the selection of esters (suchas the 2-octyl ester) that will not cause irritation or infec-tions of the areas being treated.

Cyanoacrylates are also used widely in a number of indus-trial and household adhesives, perhaps the best known ofwhich is Super GlueTM. Manufacturers use cyanoacrylatesin the assembly of many products, including trophies, golf


CYANOACRYLATE

clubs and other sports equipment, tools, digital watches,optical lenses, electronic components, lampshades, plastics,scientific instruments, loudspeakers, shoes, jewelry, andvideocassettes. Automobile makers use the product to attachtrim to cars and trucks. The cyanoacrylates come in a greatvariety of formulations that make them suitable for bondingwith special types of materials (such as ceramics, metals,wood, plastics, and glasses) and under a variety of specializedconditions (such as high or low temperature or very dry ordamp conditions).

Cyanoacrylates are also used by forensic scientists tocollect fingerprints at crime scenes. The object to be testedis suspended inside a container with at least one transparentside. A few drops of Super Glue or similar cyanoacrylateproduct is added to the container and the container is sealedand heated to about 100�C (212�F). That heat causes vapor-ization and polymerization of the cyanoacrylate, resulting inthe formation of distinctive white print patterns, a processthat make take two hours or more. This cyanoacrylatefuming test has now become the procedure of choice forthe detection of latent prints deposited on non-porousobjects, such as glass, plastic, rubber, and leather.

Cyanoacrylates bond to skin as quickly and tightly asthey do to other materials, so care is required in their use.

Interesting Facts

• The commercial success ofcyanoacrylates as glueswas assured in 1959 whenHarry Coover appeared onthe television show I’ve

Got a Secret and used theproduct to lift host GaryMoore off the floor with asingle drop of EastmanKodak’s Super GlueTM.

• The polymerization ofcyanoacrylates with water

begins as soon as the glueis spread on a material, anda strong bond is formedalmost immediately.However, polymerizationcontinues for a number ofhours and is not completefor 24 to 48 hours, at whichpoint the bonding is con-siderably stronger than inthe first few minutes ofapplication.


CYANOACRYLATE

They are skin and eye irritants, and so should always be usedin an area with good ventilation. Exposure to high levels ofcyanoacrylate gas can cause severe respiratory problems, andin the most extreme cases can result in death.


‘‘Cyanoacrylates.’’ Impact Adhesives.http://www.impact adhesives.com/pages/cyano.html (accessedon October 6, 2005).

Davidson, Elaine. ‘‘Cyanoacrylates.’’http://www.repairantiques.com/cyanoacrylates.html (accessedon October 6, 2005).

Fernandez, Tania, and Val Bliskovsky. ‘‘Cyanoacrylate Technology:Stay Glued.’’ Pharmabiz.com.http://www.pharmabiz.com/article/detnews.asp?articleid=13609&sectionid=46 (accessed on October 6, 2005).

‘‘Methyl 2 Cyanoacrylate (MCA); Ethyl 2 Cyanoacrylate (ECA).’’Occupational Safety and Health Administration.http://www.osha slc.gov/dts/sltc/methods/organic/org055/org055.html (accessed on October 6, 2005).

‘‘Methyl Cyanoacrylate and Ethyl Cyanoacrylate.’’ InternationalProgramme on Chemical Safety.http://www.inchem.org/documents/cicads/cicads/cicad36.htm#9.0 (accessed on October 6, 2005).

Schwade, Nathan D. ‘‘Wound Adhesives: 2 Octyl Cyanoacrylate.’’eMedicine: Instant Access to Medicine.http://www.emedicine.com/ent/topic375.htm (accessed onOctober 6, 2005).

See Also Formaldehyde

Words to Know



POLYMERIZATION The process of creating apolymer; a reaction that causes a polymerto form.



CYANOACRYLATE

OTHER NAMES:Cobalamin;vitamin B12

FORMULA:C63H88CoN14O14P


cobalt, nitrogen,oxygen, phosphorus

COMPOUND TYPE:Heterocyclic ring

(organic)

STATE:Solid


MELTING POINT:Undetermined;

greater than 300�C(575�F)


SOLUBILITY:Soluble in water in

alcohol; insoluble inacetone, ether, and

chloroform

Cyanocobalamin

KE

YF

AC

TS

OVERVIEW

Cyanocobalamin (sye-AN-oh-koh-BAL-uh-min) is morecommonly known as vitamin B12. At least three activeforms of the vitamin are known. They include hydroxoco-balamin and nitrocobalamin, in addition to cyanocobala-min, all with slightly different molecular structures. Cyano-cobalamin occurs as dark red crystals or a red powder thatis odorless and tasteless. When heated, the compound dar-kens above 200�C (392�F), but does not melt when heatedfurther.

Cyanocobalamin is required for the synthesis of DNAin cells and for the proper functioning of red blood cellsand nerves. A deficiency of vitamin B12 in the diet resultsin a condition known as pernicious anemia, a condition inwhich red blood cells are smaller in size, number, andhemoglobin content than normal red blood cells. Thesedefects result in general weakness, nervous disorders, gas-trointestinal disturbances, and, eventually and inevitably,death.

H3CC

CC

C

CCC

C

C

C

N N

N N

CH3

CH3

NH2

CH3C C

CO C

O

C CC

ONH2C

CC

H2N

CCCC

C

C

NH

O

OOHO

OH

P

C

CO

C

C CC

CCC

CH3H3C C

C

C

CC

O

H3C

H3CCH3

H2N

C

CC

C OH2N

C

O NH2

HOCC

N

C

Co

NH CN


The earliest research on pernicious anemia dates to

the 1920s when American physician George Hoyt Whipple(1878–1976) found that anemia in dogs could be cured by

feeding them beef liver. Inspired by this work, Americanphysicians William Murphy (1892–1987) and George Minot

(1885–1950) discovered that feeding pernicious anemiapatients beef liver cured the disease. These discoveries led

to the suspicion that one of the B vitamins present in liverwas responsible for the cure of pernicious anemia. Scientistseven invented a name for the missing vitamin, vitamin B12,

long before it was actually discovered. The problem,unknown to researchers at the time, was that vitamin B12

was such a complex molecule that its isolation and identifi-cation was a significant challenge.

In 1948, American chemist Karl Folkers (1906–1997) andhis research team discovered that they could measure

Cyanocobalamin. Blue atomsare nitrogen; yellow atomis cobalt; green atom is

phosphorous; black atoms arecarbon, white atoms are

hydrogen; red atomsare oxygen. Gray sticks aredouble bonds; striped sticks

show benzene ring.P U B L I S H E R S R E S O U R C E G R O U P


CYANOCOBALAMIN

amounts of the vitamin by measuring the growth rate ofbacteria that grew on vitamin B12. Soon the team learnedhow to purify the vitamin, which formed small red crystalsthat many scientists consider quite beautiful. It still tookmany years for scientists to determine exactly how the enor-mous molecule was structured. In 1956, however, the Britishchemist Dorothy Hodgkin (1910–1994) determined its chemi-cal structure, allowing her American colleague Robert BurnsWoodward (1917–1979) to actually synthesize the compound,an accomplishment of enormous complexity that took fifteenyears to complete.

HOW IT IS MADE

Vitamin B12 is made naturally by bacteria that live in theintestines of all animals, including humans, as well as in soil.It binds to protein in food. Plants do not synthesize vitaminB12. Manufacturers who make vitamin B12 supplements usebacteria to grow the vitamin by a process similar to thatwhich occurs naturally. Good food sources of vitamin B12

include animal foods, such as fish, meat, poultry, eggs, milk,cheese, and yogurt; as well as fortified cereals. People who donot eat animal products should be sure to select foods for-tified with artificially produced vitamin B12, because thesynthetic vitamin is produced by a natural process that doesnot involve the destruction of animals or the consumption ofanimal products.

Interesting Facts

• Cyanocobalamin gets itsname because it containsthe metal cobalt.

• For a period of time, theonly cure available forpernicious anemia was forpatients to eat about a

pound of liver every day.Since many patients dis-liked that diet, they werevery happy when syntheticvitamin B12 supplementsbecame available.


CYANOCOBALAMIN


Cyanocobalamin is essential to human health. The body

cannot make properly functioning red blood cells, whiteblood cells, or platelets without it. It is also essential for

the production of DNA and nerve cells. People whose dietis deficient in cyanocobalamin are likely to develop per-nicious anemia. The symptoms of this disorder include

fatigue, weakness, numbness, blurred vision, poor memory,confusion, hallucinations, personality changes, a smooth

shiny tongue, stiffness, diarrhea, poor appetite, slowgrowth in children, and reduced sensitivity to pain and

pressure.


Brody, Tom. Nutritional Biochemistry. San Diego: Academic Press,1998.

‘‘Dietary Supplement Fact Sheet: Vitamin B12.’’ National Institutesof Health, Office of Dietary Supplements.http://ods.od.nih.gov/factsheets/vitaminb12.asp (accessed onOctober 6, 2005).

‘‘Nascobal Gel.’’ Nastech Pharmaceutical Company.http://www.tzamal medical.co.il/tzamal pharma productsnascobal.htm (accessed on October 6, 2005).

Words to Know

DNA Deoxyribonucleic acid, a material witha cell that carries its genetic informa-tion and is capable of reproducingitself.

HETEROCYCLIC RING A compound whosemolecules contain at least one ring in

which some element other than carbon isalso present.



CYANOCOBALAMIN

Opt, Robert C., and David J. Brown. ‘‘Vitamin B12 Deficiency.’’American Academy of Family Physicians. March 1, 2003. Alsoavailable online athttp://www.aafp.org/afp/20030301/979.html (accessed onOctober 6, 2005).


CYANOCOBALAMIN

OTHER NAMES:Benzenemethanamium;

other names arepossible

FORMULA:C28H34N2O3


nitrogen, oxygen


STATE:Solid


MELTING POINT:166�C to 170�C (331�F

to 338�F)


SOLUBILITY:Soluble in water andalcohol; insoluble in

ether

Denatonium Benzoate

KE

YF

AC

TS

OVERVIEW

Denatonium benzoate (de-an-TOE-nee-um BEN-zoh-ate) isgenerally regarded as having the most bitter taste of anycompound known to science. It is sold under the trade nameof Bitrex�. Although denatonium benzoate has a powerfultaste, it is colorless and odorless. The taste is so strong,however, that most people cannot tolerate a concentrationof more than 30 parts per million of denatonium benzoate.Solutions of denatonium benzoate in alcohol or water arevery stable and retain their bitter taste for many years.Exposure to light does not lessen the compound’s bitter taste.

Denatonium benzoate compound was discovered in 1958by a scientist named W. Barnes, who was working for thechemical firm of T. & H. Smith, in Edinburgh, Scotland.Barnes was interested in developing a new anesthetic, morepowerful than those already available to physicians. Hedecided to focus his research on lidocaine, a very popularanesthetic, and compounds chemically related to it. In oneline of his experiments, Barnes added a single benzoyl group

H

HH

H

H

C

C

C

CC

CC

CC

C

C

C

C

CC

C

NN+

H3CCH3

H3CH3C

O

CO O-

C

H

H

H

H

H

H

H

H

H

H

H

HHH

H

HC

C

CH

C

C

C


(benzoic acid with a hydrogen removed: C6H5COO�) to anitrogen atom in lidocaine. The resulting compound wasdenatonium benzoate. Although the compound had littleeffectiveness as an anesthetic, Barnes noted that it had apeculiar odor and taste. The Smith company decided toexploit this unusual property of denatonium benzoate, andobtained a patent for it under the name of Bitrex�. Today,the primary manufacturer of Britex� in the world is theMacfarlan Smith corporation of Edinburgh.

HOW IT IS MADE

The process by which denatonium benzoate is made isa proprietary secret of the Macfarlan Smith corporation.A proprietary secret is a method of making a product for which

Denatonium Benzoate. Redatoms are oxygen; white atomsare hydrogen; black atoms are

carbon; and blue atoms arenitrogen. Gray sticks indicatedouble bonds; striped sticks

show benzene rings.P U B L I S H E R S R E S O U R C E

G R O U P

DENATONIUM BENZZOATE


a company holds a patent and the details of which it doesnot disclose to the general public.


One of the first and most important uses of denatoniumbenzoate was as an additive to methanol (methyl alcohol;wood alcohol). Although ethanol (ethyl alcohol; grain alcohol)has some harmful effects on humans, especially if taken inexcess, it is relatively safe to drink in beer, wine, and otheralcoholic drinks. By contrast, methanol is highly toxic. Any-one who accidentally or intentionally consumes methanol islikely to experience serious health effects, including death.By adding a small amount of denatonium benzoate to metha-nol, consumers are discouraged—and usually prevented—fromdrinking the substance.

Denatonium benzoate has many other applications. Forexample, it can be used in a dilute solution to brush on thefingernails of people who are compulsive fingernail-biters.Some parents use a similar solution on the thumbs of childrenwho suck their thumbs more than they should. Denatoniumbenzoate is also used as an animal repellent. Products contain-ing denatonium benzoate can be sprayed on trees, brushes,crops, and other material to prevent deer from grazing onthose products. One of the product’s first applications wasas a treatment on pig’s tails to prevent pigs from biting

Interesting Facts

• The claim that denatoniumbenzoate is the mostbitter tasting chemicalknown is based not onscientific tests but onhuman taste tests alone.No automated test existsfor determining thebitterness of asubstance.

• Oregon was the first state inthe United States to requirethe addition of Bitrex�

to antifreeze and carwindshield washer fluid. Therequirement was institutedto prevent people fromdrinking such productsaccidentally or, in the caseof alcoholics, intentionally.



each other. The coatings on electric cables are sometimesimpregnated with a denatonium benzoate solution to discou-rage rats from chewing on them.

Some of the other applications in which denatoniumbenzoate has been used include the following:

• In liquid laundry detergents;

• In fabric conditioners;

• In toilet cleaners;

• In disinfectants;

• In household antiseptics;

• In kitchen, bathroom, and floor cleaners;

• In paint products and paint brush cleaners;

• In personal care products, including bath foam, soaps,perfume and after shave lotions, nail polish remover,shampoo, and shower gel;

• In pesticides, such as insecticides, rodenticides, slugbait, and ant bait;

• In herbicides; and

• In a wide variety of automotive care products, such asantifreezes, coolants, and car cleaning materials.

In all of these cases, the purpose of adding denatoniumbenzoate is to change the taste of the product just enough toprevent someone, especially children, from eating a sub-stance that could cause them harm.

Despite its bitter taste, denatonium benzoate appears topose little or no hazard to human health. Exposure to thepure compound may cause respiratory discomfort, but onlypeople working with the substance directly are likely toencounter this problem.


‘‘About Bitrex�.’’ Market Actives.http://www.marketactives.com/home.html (accessed on October7, 2005).

‘‘Contains Bitrex.’’ Macfarlan Smith.http://www.bitrex.com/home.htm (accessed on October 7,2005).



‘‘Denatonium Benzoate.’’ C Tech Corporation.http://www.ctechcorporation.com/benzoate.htm (accessed onOctober 7, 2005).

‘‘The Most Bitter Substance.’’ Center for the Science & Engineeringof Materials.http://www.csem.caltech.edu/material_of_month/bitrex.html(accessed on October 7, 2005).



OTHER NAMES:Difluorodichloro-

methane; Freon 12�

FORMULA:CCl2F2

ELEMENTS:Carbon, chlorine,

fluorine


hydrocarbon; alkylhalide (organic)

STATE:Gas


MELTING POINT:�158�C (�252�F)



in water; soluble inalcohol and ether

Dichlorodifluoro-methane

KE

YF

AC

TS

OVERVIEW

Dichlorodifluoromethane (DIE-klor-oh-DIE-floor-oh-METH-ane) belongs to a family of compounds called the chlorofluoro-carbons (CFCs) that consist of carbon, chlorine, and fluorine atomsin varying arrangements. They can be considered as derivativesof alkanes, organic compounds consisting of carbon and hydro-gen only, in which all of the hydrogen atoms have been replacedby chlorine and/or fluorine atoms. Chlorofluorocarbons are alsoreferred to by their trade names, assigned to them by the DuPontcorporation, which holds patents for their production. Dichloro-difluoromethane, for example, is also known as Freon12�. Thenumbers in each compound’s Freon name specify the carbonatoms on which the chlorine and/or fluorine atoms are located.Freon12� is also known as refrigerant 12, propellant 12, and halon122. The term halon refers to a related family of compoundsconsisting of carbon, chlorine, fluorine, bromine, and/or iodine.

Dichlorodifluoromethane is the most widely used of allFreons�. It is a colorless, nonflammable gas that smells likeether in high concentrations.

Cl F

FCl

C C


During the late 1800s and early 1900s, ammonia (NH3)and sulfur dioxide (SO2) were the gases most commonly usedin refrigeration systems. These substances were toxic andflammable, however, and their use resulted in many deathsand injuries. Three U.S. companies, DuPont, General Motors,and Frigidaire, began searching for a nonflammable, non-toxic alternative to ammonia and sulfur dioxide in theirrefrigeration products. In the late 1920s, Thomas Midgley(1889–1944), a researcher at General Motors, discovered sucha compound, dichlorodifluoromethane. It enabled cooling sys-tems to operate more efficiently and more safely. DuPont,which had joined forces with General Motors in the searchfor a new coolant, began manufacturing Freon in 1930.

For several decades, Freon� was widely used in refrigera-tion and for a number of other industrial applications. Inthe 1970s, two scientists at the University of California,F. Sherwood Rowland (1927– ) and Mario Molina (1943– )discovered that CFCs escaping from appliances on the Earth’ssurface drifted upward into the stratosphere, where theywere exposed to intense ultraviolet radiation from the Sun.

Dichlorodifluoromethane.

Black atoms are carbon;turquoise atoms are flourine;and green atoms are chlorine.

Gray stick shows a double bond.P U B L I S H E R S R E S O U R C E G R O U P

DICHLORODIFLUOROMETHANE


That radiation caused the decomposition of CFCs into a num-ber of products, one of which was chlorine. The chlorineproduced in this breakdown, in turn, attacked ozone molecules(O3) in the stratosphere and converted them into normaloxygen molecules (O2).

Once recognized, this series of reactions became a matterof serious concern to scientists. The ozone layer absorbsultraviolet radiation from the Sun, reducing the risk of skincancer and other health problems produced by ultravioletradiation. In 1987, twenty-seven nations had signed the Mon-treal Protocol on Substances that Deplete the Ozone Layer,which called for a 50-percent reduction in CFC production bythe year 2000. An amendment to the protocol adopted in1990 went even further, banning production of CFCs alto-gether in developed countries. Eventually, 148 countries wereto sign the Montreal Protocol. By 1996, CFC production hadcome essentially to a halt except for a few developing nationsand for use in certain specific applications, such as asthmainhalers. A decade later, scientists reported evidence that theozone layer had begun to show signs of recovery.

Since the ban on CFC production has been adopted, manu-facturers are replacing Freon� products with two relatedgroups of compounds, the hydrochlorofluorocarbons (HCFCs)and hydrofluorocarbons (HFCs). These hydrogen-containingcompounds are less energy efficient than the CFCs, but theyare considered safer (although not entirely safe) for theenvironment.

HOW IT IS MADE

Dichlorodifluoromethane is made by reacting carbon tet-rachloride (CCl4) with hydrogen fluoride gas (H2F2) in thepresence of a catalyst, usually antimony pentafluoride(SbF5). In this reaction, two of the chlorines present in car-bon tetrachloride are replaced by two fluorines from hydro-gen fluoride, producing dichlorodifluoromethane.


Dichlorodifluoromethane and other Freons� were onceused for many commercial applications: as refrigerants forair conditioners and refrigerators; as an aerosol propellantfor hair sprays, insecticides, paints, adhesives, and cleaners;



and as a foaming agent in the manufacture of shippingplastics. Its relative nontoxicity made these materials usefulfor food preservation and even for chilling cocktail glasses.Some other former uses of the Freons� include the following:

• As a rocket propellant;

• In solvents used in the manufacture of paints andvarnishes;

• In the preparation of frozen sections of tissue;

• For the freezing of foods as a method of preservation;

• In water purification systems;

• As an agent for detecting leaks.

Companies favored Freons� for so many uses becausethey are both nontoxic and nonreactive in the troposphere.

This property turned out to be a disadvantage also since itmeans that Freons� remain in the atmosphere for such longperiods of time that they can eventually reach the strato-

sphere, where they pose a serious threat to the ozone layer.

Freons� may pose a health hazard if inhaled in largeamounts. They displace oxygen in the air, causing dizziness,drowsiness, irregular heartbeat, cardiac arrest, unconscious-

Interesting Facts

• In 1930, Thomas Midgleydemonstrated the safety ofFreon� at a meeting of theAmerican Chemical Societyby breathing in the gas andthen breathing it out toextinguish a candle flame.

• The production ofdichlorodifluoromethaneworldwide rose from about150 million kilogramsannually in 1960 to morethan 750 million kilograms(1.65 billion pounds)

annually in 1990. By 1996,because of the MontrealProtocol, it had droppedto less than 50 millionkilograms (110 millionpounds) annually.

• One chlorine atomproduced in thestratosphere by thedecomposition of a CFCmolecule can destroy100,000 molecules ofozone.



ness, and death by suffocation. Sprayed on the skin, Freons�

can cause frostbite, damage produced by exposure to freez-ing temperatures. The ignition of Freons� also poses hazardsto human health because of the release of toxic gases suchas hydrogen chloride (HCl), hydrogen fluoride (H2F2), andphosgene (COCl2).


Baker, Linda. ‘‘The Hole in the Sky (Ozone Layer).’’ E (November2000): 34.

Cagin, Seth, and Philip Dray. Between Earth and Sky: How CFCs

Changed Our World and Endangered the Ozone Layer. NewYork: Pantheon Books, 1993.

‘‘Dichlorodifluoromethane.’’ NIOSH Pocket Guide to ChemicalHazards.http://www.cdc.gov/niosh/npg/npgd0192.html (accessed onOctober 7, 2005).

Elkins, James W. ‘‘Chlorofluorocarbons (CFCs).’’ National Oceanicand Atmospheric Administration (NOAA).http://www.cmdl.noaa.gov/noah/publictn/elkins/cfcs.html (accessed on October 7, 2005).

‘‘Gas Data.’’ Air Liquide.http://www.airliquide.com/en/business/products/gases/gasdata/index.asp?GasID=22 (accessed on October 7, 2005).

See Also Ammonia; Hydrogen Chloride; Sulfur Dioxide

Words to Know

CATALYST A material that increases therate of a chemical reaction withoutundergoing any change in its ownchemical structure.

STRATOSPHERE The layer of the Earth’satmosphere extending from about 15kilometers (8 miles) to about 50

kilometers (30 miles) above the Earth’ssurface.

TROPOSPHERE The lowest layer of theEarth’s atmosphere, reaching to about8 miles (15 kilometers) above the Earth’ssurface.



OTHER NAMES:DDT; see Overview

for additional names

FORMULA:(ClC6H4)2CHCCl3


chlorine

COMPOUND TYPE:Halogenatedhydrocarbon

(organic)

STATE:Solid




SOLUBILITY:Insoluble in water;slightly soluble in

ethyl alcohol; solublein ether, acetone, and

benzene

Dichlorodiphenyl-trichloroethane

KE

YF

AC

TS

OVERVIEW

Dichlorodiphenyltrichloroethane (DI-klor-oh-DI-fee-nul-TRI-klor-oh-eth-ane) is a colorless crystalline or white powderymaterial with a slight aromatic odor. It is far better knownby its acronym, DDT. DDT was first synthesized in 1873 byGerman chemist Othmar Zeidler (1859–1911) as a project forhis doctoral thesis. However, the compound was essentiallyignored by other chemists and remained a laboratory curi-osity for more than sixty years.

Then, in 1939, Swiss chemist Paul Hermann Muller(1899–1965) discovered that DDT is very effective in killinga wide variety of insects including the common housefly,the mosquito, the louse, and the Colorado beetle. Muller’sdiscovery gave medical workers a powerful tool in preventinga host of infectious diseases carried by these insects, includ-ing bubonic plague, dengue fever, elephantitis, encephalitis,leishmaniasis, malaria, sleeping sickness, typhus, yaws, andyellow fever. The compound was used widely during WorldWar II (1939–1945) to control insects in both military and

Cl Cl

H

CC

H HC

C

Cl

C

C

CC

CCl Cl

H H

H

H

C

CC

CC

H

H


civilian facilities. It was credited for reducing the spread ofwhat is probably the world’s most common infectious disease,malaria. Once common throughout the world, malaria wasessentially eliminated in Europe and North America as aresult of the use of DDT.

In addition to its public health applications, DDT haslong been a popular agricultural pesticide. The compoundkills many of the insects and other pests that attack cropsand reduce the productivity that can be achieved by farmers.

The fate of DDT took a dramatic turn in the 1960s,however, largely as the result of a single book, Silent Spring,

written by American biologist and environmentalist RachelCarson (1907-1964). The book described a situation in whichthe use of pesticides such as DDT might become so commonthat the chemical begins to kill off other organisms, such asbirds, as well as insects. Carson’s book came at a time whenscientific evidence of the environmental harm done by pes-

Dichlorodiphenyltrichloroethane

(DDT). Black atoms are carbon; greenatoms are chlorine; white atoms are

hydrogen. Bonds in the benzene ringsare represented by the double stripedsticks. White sticks show single bonds.



DICHLORODIPHENYLTRICHLOROETHANE

ticides was just becoming available. The work was soonadopted by the growing environmental movement as a well-documented warning of what might happen if the uncon-trolled use of pesticides did not end. People began to worryabout the ill effects of DDT and other pesticides not only onthe environment, but also on human health.

In 1972, the U.S. Environmental Protection Agencyannounced that DDT could no longer be used in the UnitedStates because of the risk it posed for human health and theenvironment. A number of other developed nations soonfollowed the EPA’s action. In 2001, a conference sponsoredby the United Nations, called the Stockholm Convention onPersistent Organic Pollutants, adopted a statement callingfor the eventual elimination of a dozen pesticides, knownas ‘‘the dirty dozen,’’ including DDT. Because of its effective-ness against malaria and other infectious diseases, DDT wasgiven a waiver for use by public health officials in nationswhere the compound had not been banned.

DDT is also known by the following names: 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane; 1,10-(2,2,2-trichloroethylidene)-bis (4-chlorobenzene); 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane; 1,1,1-trichloro-2,2-di(p-chlorophenyl) ethane; 1,1-bis(4-chlorophenyl)-2,2,2-trichlorethane; 1,1-bis(p-chlorophenyl)-2,2,2-trichlorethane; 2,2,2-trichloro-1,1-bis (4-chlorophenyl)ethane; and 4,40-dichlorodiphenyltrichloroethane.

HOW IT IS MADE

DDT is prepared commercially in the reaction betweenchloral (CCl3CHO) and chlorobenzene (C6H5Cl): CCl3CHO +2C6H5Cl ! (ClC6H4)2CHCCl3.


DDT is no longer used in the United States and othernations where it has been banned. It is still used in a numberof developing nations for the control of infectious diseasesspread by insects that can be killed by DDT. Malaria is themost important of these diseases.

The health hazards posed by DDT are still the subject ofintense debate among agricultural scientists, public healthexperts, and other authorities. Abundant evidence exists toshow that DDT can have a variety of harmful effects on



animals, ranging from marine algae to bald eagles. The com-pound may also have serious health effects on humans,including mild to serious damage to the liver, kidneys, andcentral nervous system. DDT has also been classified as aprobable carcinogen by the U.S. Environmental ProtectionAgency although no definite evidence for that classificationis yet available.

On the other hand, critics have pointed out that littlescientific evidence exists for the belief that DDT is a serioushealth threat to humans. In one experiment, humans tookcapsules containing small amounts of DDT every day for18 months and experienced no measurable health effects asa result. Some observers argue that the benefits gained from

Interesting Facts

• Peak use of DDT in theUnited States occurred in1958 when about 35 millionkilograms (80 millionpounds) of the compoundwere sprayed on U.S.farmlands.

• Extensive data exists tosupport the advantages ofusing DDT against malaria.For example, there weremore than 2.8 million casesof malaria in Sir Lankain 1948, before theintroduction of DDT.Six years later, after thecompound had been putinto use in the country, thenumber of malaria casesdropped to 17. Five yearslater, after the use of DDThad been discontinued, thenumber of malaria casesrose to 2.5 million.

• Countries that havebanned the use of DDTinclude Australia (1967),Sweden (1970), Cuba (1970),Germany (1974), Poland(1976), the United Kingdom(1984), Chile (1985), SouthKorea (1986), Switzerland(1986), and Canada (1989).

• DDT is still manufacturedlegally in only threecountries: China, India,and Indonesia. It may alsobe produced, althoughillegally, in Mexico.

• DDT often occurs incombination with twoother related compounds,dichlorodiphenyldichloro-ethane (DDD) anddichlorodiphenyldichloro-ethylene (DDE).



using DDT as an agricultural and public health pesticide—benefits such as the elimination of diseases like malaria—farexceed the risks posed by the chemical to human health andthe environment.


Carson, Rachel. Silent Spring. Boston: Houghton Mifflin, 1962.

‘‘DDT.’’ National Safety Council.http://www.nsc.org/library/chemical/ddt.htm (accessed onDecember 29, 2005).

‘‘DDT (dichlorodiphenyltrichloroethane).’’ Extoxnet.http://ace.orst.edu/cgi bin/mfs/01/pips/ddt.htm (accessed onDecember 29, 2005).

Dunlap, Thomas. DDT: Scientists, Citizens, and Public Policy.

Princeton, NJ: Princeton University Press, 1983.

Edwards, J. Gordon, and Steven Milloy. ‘‘100 Things You ShouldKnow about DDT.’’ JunkScience.com.http://www.junkscience.com/ddtfaq.htm (accessed on December29, 2005).

Karaim, Reed. ‘‘Not So Fast with the DDT: Rachel Carson’s Warnings Still Apply.’’ American Scholar (June 2005): 53 60.

McGinn, Anne Platt. ‘‘Malaria, Mosquitoes, and DDT: The ToxicWar against a Global Disease.’’ World Watch (May 1, 2002):10 17.

‘‘ToxFAQsTM for DDT, DDE, and DDD.’’ Agency for Toxic Substances and Disease Registry.http://www.atsdr.cdc.gov/tfacts35.html (accessed on December29, 2005).



OTHER NAMES:2-propanone; acetone

FORMULA:CH3COCH3


oxygen

COMPOUND TYPE:Ketone (organic)

STATE:Liquid




SOLUBILITY:Miscible with water,

alcohol, ether,benzene, and

chloroform

Dimethyl Ketone

KE

YF

AC

TS

OVERVIEW

Dimethyl ketone (DYE-meth-el KEY-tone) is a clear, color-less, highly volatile and highly flammable liquid with acharacteristic sweet odor and taste. The compound is almostuniversally known in chemistry laboratories and industrialapplications by its common name of acetone.

Acetone was apparently first prepared in 1610 by theFrench alchemist Jean Beguin (c. 1550–c. 1650). Beguinobtained acetone by heating lead acetate (also known asSaturn’s salt) to a high temperature. He obtained a sweet-smelling, very flammable liquid that he named ‘‘burningspirit of Saturn.’’ One of the first uses to which the substancewas put was as a solvent in the extraction of the activeconstituents of opium. In 1833, the French chemist AntoineBussy (1794–1882) gave the compound its modern name ofacetone. The correct chemical formula for acetone was deter-mined independently in 1832 by the French chemist JeanBaptiste Andre Dumas (1800–1884) and the German chemistJustus von Liebig (1803–1873).

CH3H3CC

O


HOW IT IS MADE

Most of the acetone produced today is made by one offour methods:

• In the Hock process, cumene [C6H5CH(CH3)2] is firstoxidized to produce cumene hydroperoxide[C6H5C(CH3)2COOH], which is then reduced to produceacetone and phenol (C6H5OH); or

• Isopropyl alcohol (2-propanol; CH3CHOHCH3) is oxidizedover a catalyst to obtained acetone; or

• Butane (C4H10) is oxidized to obtain acetone; or

• Acetone is obtained as a by-product of the manufactureof glycerol [C3H5 (OH)3].


Acetone’s primary applications are based on its ability todissolve such a wide array of organic substances. It is used asa solvent for paints, varnishes, lacquers, inks, glues, rubbercements, fats, oils, waxes, and various types of rubber andplastics. It is perhaps best known to the average person asthe primary ingredient in nail polish remover. The largestsingle use of the compound is as a raw material in themanufacture of other organic chemicals, such as chloroform,

Dimethyl ketone. Red atom isoxygen; white atoms are

hydrogen; and black atoms arecarbon. Gray sticks indicatedouble bonds. P U B L I S H E R S


DIMETHYL KETONE


acetic acid, iodoform, bromoform, isoprene, rayon, and photo-graphic film. It also finds application in storing acetylenegas (because it absorbs up to 24 times its own weight of thegas), to clean and dry chemical equipment and electronicparts, and for the extraction of components of plant andanimal tissues.

The primary safety concern about acetone is its extremeflammability. Workers who handle the compound must usegreat care to prevent its coming into contact or even being inthe vicinity of open flames. Under the proper conditions,acetone is also explosive. Exposure of the skin, eyes, andrespiratory system to acetone may produce mild symptoms,such as dizziness, headaches, and disorientation and irrita-tion of the eyes and skin. Such conditions are rare, however,and no long-term health effects of the compound have as yetbeen discovered.


‘‘Acetone.’’ International Labour Organization.http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc00/icsc0087.htm (accessed onOctober 7, 2005).

‘‘Safety (MSDS) data for propanone.’’ Physical and TheoreticalChemistry Lab Safety.http://ptcl.chem.ox.ac.uk/MSDS/PR/propanone.html (accessedon October 7, 2005).

‘‘Toxicological Review of Acetone.’’ Environmental ProtectionAgency.http://www.epa.gov/iris/toxreviews/0128 tr.pdf (accessed onOctober 7, 2005).

Words to Know

MISCIBLE able to be mixed; especiallyapplies to the mixing of one liquid withanother.

VOLATILE A term describing a liquid thatcan be easily changed to gas.


DIMETHYL KETONE

OTHER NAMES:Acetic acid; ethyl

ester; acetic ether

FORMULA:CH3COOC2H5


oxygen


STATE:Liquid





water; miscible withalcohol, ether, and

benzene

Ethyl Acetate

KE

YF

AC

TS

OVERVIEW

Ethyl acetate (ETH-uhl ASS-uh-tate) is a clear, colorless,volatile, flammable liquid with a pleasant fruity odor. Itsappealing odor and fruity taste (in dilute solutions) explainsone of its primary uses: as an additive in foods and drugs toimprove their flavor.

HOW IT IS MADE

Ethyl acetate occurs naturally in fruits, where it isresponsible for the pleasant odor and taste of the fruit. It isalso found in yeasts and sugar cane. The compound is madesynthetically by reacting acetic acid (CH3COOH) with ethanol(ethyl alcohol; CH3CH2OH) in the presence of a sulfuric acidcatalyst.


Ethyl acetate’s primary use is as a solvent in a varietyof commercial and industrial applications. About 65 percent

CH3H3CCC

HH

O

O


of all ethyl acetate produced is used as a solvent in lac-

quers, varnishes, shellacs, inks, coatings for airplanes, andother types of coatings. Another 12 percent of the ethylacetate produced is used as a solvent for various types of

plastics. The remaining amount of ethyl acetate is used in

Ethyl acetate. Red atoms areoxygen; white atoms are

hydrogen; and black atomsare carbon. Gray sticks indicate



Interesting Facts

• Ethyl acetate is a byproductof the fermentation ofgrapes in the wine-makingprocess. The compound isalso produced as wine agesin barrels and bottles. Amoderate amount of ethyl

acetate contributes to thepleasant fruity taste andodor of some wines. But inexcess, it can give wine aslightly ‘‘off’’ taste andodor.


ETHYL ACETATE

the preparation of other organic compounds; as a flavor-enhancing additive for foods and pharmaceuticals; in themanufacture of smokeless power, leather products, and

photographic films and plates; and for the cleaning oftextiles.

The primary safety concern with regard to ethyl acet-

ate is its flammability. Both the liquid and its vaporsignite at temperatures above 200�C (392�F). Exposure to

ethyl acetate vapors can also irritate the eyes, nose, andrespiratory system. There is no evidence that normal

amounts of ethyl acetate are carcinogenic or toxic tohumans.


‘‘Ethyl Acetate.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/e2850.htm (accessedon October 7, 2005).

‘‘Ethyl Acetate.’’ National Institute of Standards and Technology.http://webbook.nist.gov/cgi/cbook.cgi?Name=ethyl+acetate&Units=SI (accessed on October 7, 2005).

‘‘Ethyl Acetate.’’ Spectrum Laboratories.http://www.speclab.com/compound/c141786.htm (accessed onOctober 7, 2005).

See Also Acetic Acid; Ethyl Alcohol

Words to Know






ETHYL ACETATE

OTHER NAMES:Ethanol; grain

alcohol; alcohol; ethylhydrate

FORMULA:CH3CH2OH


oxygen

COMPOUND TYPE:Alcohol (organic)

STATE:Liquid




SOLUBILITY:Miscible with water,ether, acetone, and

most commonorganic solvents

Ethyl Alcohol

KE

YF

AC

TS

OVERVIEW

Ethyl alcohol (ETH-uhl AL-ko-hol) is a clear, colorless,flammable liquid with a sharp, burning taste and a pleasant,wine-like odor. It is one of the first chemical substancesdiscovered and used by humans. Ceramic jugs apparentlydesigned to hold beer have been dated to the Neolithic Per-iod, about 10,000 BCE. Some scholars suggest that humansmay have learned how to make beer and incorporated it intotheir daily diets even before they made and used bread. Themaking and use of wine is a clear theme in Egyptian picto-graphs dating to the fourth millennium BCE. There probablydoes not exist a human culture today in which alcohol con-sumption does not occur. Today, beverages with alcohol con-tent ranging as low as two to five percent (‘‘near beer’’ andbeer) to as high as 50 percent (some forms of vodka) areknown and consumed by humans. In spite of its widespreaduse as a beverage, ethyl alcohol has a number of commercialand industrial uses that account for more than 90 percent ofall the compound produced in the United States.

OH

C H

H

H3C


HOW IT IS MADE

Ethyl alcohol is made in one of two ways: naturally,through the process of fermentation, or synthetically, begin-ning with compounds found in petroleum. Until the begin-ning of World War II, more than 90 percent of all ethylalcohol produced in the United States and other developednations was made by fermentation. Waste syrup left overfrom the production of sugar from sugar cane was treatedwith enzymes at temperature of 20�C to 38�C (68�F to 100�F)for 28 to 72 hours. Under these conditions, about 90 percentof the syrup is converted to ethyl alcohol.

Over time, synthetic methods for the production of ethylalcohol were developed. In one such method, ethylene(ethene; CH2=CH2) is treated with sulfuric acid and waterto= obtain ethyl alcohol. That method was popular duringthe 1950s and 1960s. Then, a new method for making thecompound was invented. In that process, ethylene and waterare heated together at high temperatures [300�C to 400�C(570�F to 750�F)] and high pressures [1,000 pounds persquare inch (6.9 megaPascals)] over a catalyst of phosphoricacid (H3PO4). The efficiency of this method is greater than

Ethyl alcohol. Red atom isoxygen; white atoms are




ETHYL ALCOHOL

the older method, and there are fewer environmental conse-

quences from making ethyl alcohol by this process.

As of 2003, about 94 percent of all ethyl alcohol wasproduced by fermentation. The remainder was produced by

the phosphoric acid method.


In 2005, 10,500 million liters (2,790 million gallons) ofethyl alcohol were produced by fermentation methods. Of

that amount, 92 percent was used as a fuel or an additive infuels. Many experts suggest that consumers use a mixture of

gasoline (90 percent) and ethyl alcohol (10 percent) calledgasohol as a vehicle fuel because it burns more completelyand releases fewer harmful byproducts to the environment.

Although gasohol has not yet become very popular in theUnited States, it is widely used in some other parts of the

world, most notably, in Brazil.

Of the remaining 8 percent of ethyl alcohol produced byfermentation, half was used in industrial operations, as a

solvent or intermediary in the preparation of other chemical

Interesting Facts

• All members of the alcoholfamily of organiccompounds (such asmethyl alcohol, ethylalcohol, and isopropylalcohol) are toxic to someextent. Only ethyl alcoholis safe to drink inrelatively small quantities.Even then, a blood alcoholconcentration of less than5 percent can result indeath.

• The concentration ofalcohol in a beverage isoften expressed as a‘‘proof’’ number. The proofnumber of a beverage istwice that of its alcoholconcentration. Thus, abeverage that is 80proof has an alcoholconcentration of 40percent.


ETHYL ALCOHOL

compounds; and half was used in the production of alcoholic

beverages.

In 2005, about 650 million liters (170 million gallons) ofethyl alcohol were produced by the phosphoric acid method.Of that amount, 60 percent was used for industrial solventsin the manufacture of toiletries and cosmetics, coatings andinks, detergents and household cleaners, pharmaceuticals,and other products. The remaining 40 percent was used inthe preparation of other chemical compounds, includingethyl acrylate, vinegar, ethylamines, ethyl acetate, glycolethers, and miscellaneous materials.

Ethyl alcohol commonly occurs in one of three generalforms. Absolute alcohol is ethyl alcohol that contains less than1 percent impurities, such as water. Absolute alcohol is verydifficult to make because ethyl alcohol will absorb water fromthe atmosphere or any other source that is available. The ethylalcohol used in fuels and almost all industrial operations is amixture of 95 percent ethyl alcohol and 5 percent water. Bothabsolute and 95 percent ethyl alcohol are extremely toxic.Ingestion of even very small amounts of either liquid hasserious health effects that may include death.

The alcohol with which most people commonly come intocontact is ethyl alcohol mixed with water in alcoholic bev-erages, such as beer, wine, gin, vodka, rum, or bourbon. In suchbeverages, the concentration of ethyl alcohol ranges from afew percent to 50 percent.

The effects produced by ethyl alcohol on the human bodydepend on the type of beverage consumed and the timetaken for consumption. Drinking a 5-percent beer over anhour has a very different effect on the body than drinking a50-percent vodka in five minutes.

Ethyl alcohol is a central nervous system depressant.After ingestion, it passes through a person’s stomach andthe small intestine, where it is absorbed rapidly into thebloodstream. It then travels throughout the body, interferingwith the normal functioning of the nervous system andproducing symptoms such as drowsiness, slurred speech,blurred vision, unsteady gait, impaired judgment, andreduced reaction time. With greater concentrations of alcoholin the blood, these symptoms may become more severe,resulting in coma and death.


ETHYL ALCOHOL


‘‘Alcohol.’’ Erowid.http://www.erowid.org/chemicals/alcohol/alcohol.shtml (accessedon October 7, 2005).

‘‘Alcohol: What You Don’t Know Can Harm You.’’ National Instituteon Alcohol Abuse and Alcoholism.http://pubs.niaaa.nih.gov/publications/WhatUDontKnow_HTML/dontknow.htm (accessed on October 7, 2005).

Boggan, William. ‘‘Alcohol and You.’’http://chemcases.com/alcohol/ (accessed on October 7, 2005).

‘‘Chemical of the Week: Ethanol.’’http://scifun.chem.wisc.edu/chemweek/ethanol/ethanol.html(accessed on October 7, 2005).

‘‘Ethanol.’’http://www.ucc.ie/ucc/depts/chem/dolchem/html/comp/ethanol.html (accessed on October 7, 2005).

‘‘How Alcohol Works.’’ How Stuff Works.http://science.howstuffworks.com/alcohol.htm (accessed onOctober 7, 2005).

Words to Know





ETHYL ALCOHOL

OTHER NAMES:Phenylethane;

ethylbenzol

FORMULA:C6H5C2H5


COMPOUND TYPE:Aromatic


STATE:Liquid




SOLUBILITY:Immiscible with

water; miscible withethyl alcohol and

methyl alcohol

Ethylbenzene

KE

YF

AC

TS

OVERVIEW

Ethylbenzene (eth-il-BEN-zeen) is a colorless flammable

liquid with a pleasant aromatic odor. It is an aromatic hydro-carbon, that is, a compound consisting of carbon and hydro-

gen only with a molecular structure similar to that ofbenzene (C6H6). In 2004 it ranked fifteenth among chemicals

produced in the United States. Its primary use is in themanufacture of another aromatic hydrocarbon, styrene

(C6H5CH=CH2), widely used to make a number of polymers,such as polystyrene, styrene-butadiene latex, SBR rubber,and ABS rubber.

HOW IT IS MADE

Ethylbenzene occurs to some extent as a component ofpetroleum. It can be extracted from petroleum by fractionaldistillation, the process by which individual components ofpetroleum are separated from each other by heating in adistilling tower. Ethylbenzene can also be made synthetically

C CC

C

C C

C C

HH

HH

H

HH

H

HH


by reacting benzene with ethene (ethylene; CH2=CH2) over acatalyst of aluminum chloride (AlCl3): C6H6 + CH2=CH2 !C6H5C2H5.


More than 99 percent of the ethylbenzene made is usedfor a single purpose—the production of styrene. Styrene is a

very important industrial chemical, ranking seventeenthamong all chemicals produced in the United States in 2004.

It is used to make a number of important and popular poly-mers, the best known of which may be polystyrene. Much

smaller amounts of ethylbenzene are used in solvents or asadditives to a variety of products. Some products that con-

tain ethylbenzene include synthetic rubber, gasoline andother fuels, paints and varnishes, inks, carpet glues, tobacco

products, and insecticides.

Ethylbenzene. Black atoms arecarbon; white atoms are

hydrogen. Bonds in the benzenering are represented by thedouble striped sticks. White

sticks show single bonds.P U B L I S H E R S R E S O U R C E G R O U P


ETHYLBENZZENE

The concentration of ethylbenzene in consumer productsis so low that it probably poses no threat to human health orto the environment. It may be a problem, however, when itleaks from industrial or chemical plants into the soil andbecomes part of the groundwater. In such cases, it may beconsumed by humans and other animals, or it may evaporateinto the air, where it may be breathed by humans and otheranimals. Ethylbenzene has been found in about half (731 of1467) of all the sites surveyed for pollutants by the U.S.Environmental Protection Agency, although concentrationsare so low in most cases as to pose no threat to human healthor the environment.

Ethylbenzene is an irritant to the skin, eyes, and respira-tory system. In small quantities, it may cause dizziness,tightness in the chest, and burning of the eyes. In largerdoses, it may cause narcotic effects, producing drowsinessand disorientation. The greatest safety concerns about ethyl-benzene relate to its combustibility. Since it is more densethan air, it tends to settle to the ground and travel to anysource of fire that may be near by.


‘‘Consumer Factsheet on: Ethylbenzene.’’ U.S. Environmental Protection Agency.http://www.epa.gov/safewater/contaminants/dw_contamfs/ethylben.html (accessed on December 22, 2005).

‘‘Ethylbenzene.’’ Australian Government. Department of the Environment and Heritage.http://www.npi.gov.au/database/substance info/profiles/40.html (accessed on December 22, 2005).

Words to Know


IMMISCIBLE Does not mix with anotherliquid.


POLYMER A compound consisting of verylarge molecules made of one or twosmall repeated units called monomers.


ETHYLBENZZENE

‘‘ToxFAQsTM for Ethylbenzene.’’ Agency for Toxic Substances andDisease Registry.http://www.atsdr.cdc.gov/tfacts110.html (accessed on December22, 2005).

See Also Polystyrene; Poly(Styrene-Butadiene-Styrene);Styrene


ETHYLBENZZENE

OTHER NAMES:Ethene; bicarburetted

hydrogen; olefiantgas

FORMULA:CH2=CH2


COMPOUND TYPE:Alkene; unsaturated


STATE:Gas



BOILING POINT:�103.77�C

(�154.79�F)

SOLUBILITY:Insoluble in water;slightly soluble in

ethyl alcohol,benzene, and acetone;

soluble in ether

Ethylene

KE

YF

AC

TS

OVERVIEW

Ethylene (ETH-ih-leen) is a colorless, flammable gas witha sweet odor and taste. It is the simplest alkene. Alkenes arehydrocarbons that contain one or more double bonds. Ethy-lene was first prepared in 1794 by a group of Dutch chemistsincluding J. R. Deiman, A. Paets van Troostwyk, N. Bondt,and A. Lauwerenburgh. They treated ethanol (ethyl alcohol;C2H5OH) with concentrated sulfuric acid (H2SO4) and obtainedethylene, although they were incorrect in believing that thecompound also contained oxygen.

Ethylene occurs naturally in petroleum and natural gas,but only to a very small percentage. It also occurs naturallyin plants where it functions as a hormone and has a numberof important effects on the growth and development ofplants. These effects have been used for thousands of years,although the chemical mechanism involved was not under-stood. For example, the ancient Chinese are said to haveburned incense in closed containers in order to facilitatethe ripening of pears. Although they were certainly not

H H

C C

HH


aware of the fact, the ripening effect was probably a result ofethylene gas released during combustion of the incense.

The hormonal effects of ethylene were first identified in1901 by Russian chemist Dmitri N. Neljubow. For some time,scientists had observed that leaks from the gas lamps used tolight city streets caused plants to grow old more rapidly thannormal, often with strange changes in the structure of theirleaves and stems. Neljubow was able to show that this effectwas caused by ethylene in the lamp gas. Scientists have sincelearned a great deal about the production of ethylene inplants and the effects produced by the gas on the growthand development of those plants. For example, scientistsdiscovered that ethylene is synthesized in germinatingseeds, nodes of stems, and the tissue of ripening fruits. Itsproduction is increased by flooding of the plant’s roots; bydrying of the soil; in response to environmental stress, suchas attack by pests; by aging of the plant; and by inadequateamounts of minerals in the soil. They have also learned thatethylene increases the rate at which leaves and flowers age;promotes germination of seeds and the growth of root hairs;stimulates the ripening of fruit and flowers; and increases aplant’s resistance to disease and physical damage.

Ethylene. Black atoms arecarbon; white atoms arehydrogen. The gray stick

between the two carbon atomsis a double bond. White sticks

show single bonds. P U B L I S H E R S



ETHYLENE

HOW IT IS MADE

One reference on hydrocarbons lists more than 500 meth-ods for making ethylene. From a practical standpoint, only ahandful of those methods are important. The most commonmethod of preparation involves the thermal or catalyticcracking of hydrocarbons. The term cracking refers to theprocess by which hydrocarbons from petroleum are brokendown into simpler molecules. That process is usually accom-plished by heating the petroleum for short periods of timeat high temperatures (thermal cracking) or over a catalyst(catalytic cracking). In the cracking process, hydrocarbonswith 10, 15, 20, or more carbon atoms are broken down toproduce hydrocarbons with two, three, four, or some othersmall number of carbons. Ethylene is one of the usual pro-ducts of cracking. It can be separated from the other productsof cracking because it escapes from the reaction mixtureas a gas.

Ethylene can also be produced from synthesis gas. Synth-esis gas is the term used for various mixtures of gasesproduced when steam (with or without additional oxygen) ispassed over hot coal. The steam and coal react to produce arich mixture of hydrocarbons, a mixture that usuallyincludes ethylene. Finally, ethylene can be produced in smallquantities in the laboratory by the method first used by theDutch chemists in 1794, namely by reacting ethanol withconcentrated sulfuric acid.


In 2004, U.S. chemical manufacturers produced about26.7 million metric tons (29.4 million short tons) of ethylene,making it the third most important chemical produced in thecountry in terms of volume. Over 90 percent of that ethylenewas used for the production of other chemical compounds,the most important of which were polymers and relatedcompounds, such as three major kinds of polyethylene (highdensity (HDP), low density (LDP), and linear low densitypolyethylene (LLDP)), polypropylene, ethylene dichloride,ethylene oxide, styrene, ethylbenzene, vinyl acetate, vinylchloride, ethylene glycol, polystyrene, polyvinyl chloride(PVC), trichloroethylene, styrene-butadiene rubber (SBR),and ethyl alcohol.


ETHYLENE

Smaller amounts of ethylene were used in a numberof other chemical and industrial applications. Theseincluded:

• As a spray to accelerate the ripening of fruit;


• In oxygen-ethylene torches used in welding and metal-cutting operations;

• As a specialized anesthetic.

Ethylene poses a health hazard primarily because it ishighly flammable and a serious explosive risk. It also acts asa narcotic at low concentrations, causing nausea, dizziness,headaches, and loss of muscular coordination. At higherconcentrations, it acts as an anesthetic, causing loss ofconsciousness and insensitivity to pain and other stimuli.These effects tend to be of concern primarily to people whowork directly with the gas. The amount of ethylene to whichmost people are exposed in their daily lives tends to berelatively low.

Interesting Facts

• The highest rate ofethylene production yetmeasured in plants is thatproduced by the fadingblossoms of the Vandaorchid, at 3.4 microlitersper gram of flower perhour. The Vanda orchidis extensively used in themanufacture of Hawaiianleis.

• Air in rural areas typicallycontains about 5 parts perbillion (ppb) of ethylene,while urban air generallycontains about twentytimes that amount.

• Ethylene is produced inplants in a complex seriesof reactions known asthe Yang cycle (after itsdiscoverer, S. F. Yang) thatstarts with the amino acidmethionine.

• Production of ethylenein plants is significantlyaffected by a numberof factors, such astemperature and presenceof other gases (especiallyoxygen and carbondioxide).


ETHYLENE


‘‘Ethene (ethylene): Properties, Production & Uses.’’ Aus e tute.http://www.ausetute.com.au/ethene.html (accessed on December27, 2005).

‘‘Ethylene.’’ Laboratory of Postharvest Physiology and Technology,Seoul National University.http://plaza.snu.ac.kr/~postharv/p3ethylene.pdf (accessed onDecember 27, 2005).

‘‘Ethylene.’’ National Safety Council.http://www.nsc.org/library/chemical/Ethylene.htm (accessed onDecember 27, 2005).

See Also Ethyl Alcohol; Ethylene Glycol; Ethylene Oxide;Ethylbenzene; Polyethylene; Polypropylene; Polystyrene;Polyvinyl Chloride

Words to Know


CRACKING The process by whichlarger hydrocarbons from petroleum

are broken down into simplermolecules.

POLYMER : A compound consisting ofvery large molecules made of one ortwo small repeated units calledmonomers.


ETHYLENE

OTHER NAMES:Ethylene alcohol;

monoethylene glycol

FORMULA:CH2OHCH2OH


oxygen

COMPOUND TYPE:Dihydric alcohol

(organic)

STATE:Liquid


MELTING POINT:�12.69�C (9.16�F)


SOLUBILITY:Miscible with

water, alcohol,acetone, and ether

Ethylene Glycol

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OVERVIEW

Ethylene glycol (ETH-uh-leen GLYE-kol) is clear, color-less, syrupy liquid with a sweet taste. One should not attemptto confirm the compound’s taste, however, as it is toxic. Inrecent years, more than 4 billion kilograms (9 billion pounds)of ethylene glycol has been produced in the United Statesannually. The compound is used primarily as an antifreezeand in the manufacture of a number of important chemicalcompounds, including polyester fibers, films, bottles, resins,and other materials.

Ethylene glycol was first prepared in 1859 by theFrench chemist Charles Adolphe Wurtz (1817–1884).Wurtz’s discovery did not find an application, however,until the early twentieth century, when the compound wasmanufactured for use in World War I (1914–1918) in themanufacture of explosives and as a coolant. By the 1930s,a number of uses for the compound had been found, and thechemical industry began producing ethylene glycol in largequantities.

C

H

HO

H

OH

H HC


HOW IT IS MADE

The primary method of producing ethylene glycolinvolves the hydration of ethylene oxide, a ring compoundconsisting of two methylene (-CH2) groups and one oxygenatom. Hydration is the process by which water is added to acompound. The hydration of ethylene oxide is conducted at atemperature of about 383�F (195�C) without a catalyst, or atabout 50�C to 70�C (122�F to 158�F) with a catalyst, usually astrong acid, either process resulting in a yield of at least 90percent of ethylene glycol.

Other methods of preparation are also available. Forexample, the compound can be produced directly from synth-esis gas, a mixture of carbon monoxide and hydrogen; or bytreating ethylene (CH2=CH2) with oxygen in an acetic acidsolution using a catalyst of tellurium oxide or bromide ion.

Ethylene glycol. Red atoms areoxygen; white atoms are




ETHYLENE GLYCOL


One of the first major uses of ethylene glycol was as aradiator coolant in airplanes. The compound actually madepossible a change in the design of airplanes. At one time,plain water was used as the coolant in airplane radiators. Thefaster the airplane flew, the greater the risk that its radiatorwould boil over. Adding ethylene glycol to the water raisedthe boiling point of the coolant and allowed airplanes to flyfaster with smaller radiators. This change was especiallyuseful in the construction of military airplanes used incombat.

Ethylene glycol is still used extensively as a coolant andantifreeze in cooling systems. It is also used as a deicingfluid for airport runways, cars, and boats. Brake fluids andshock-absorber fluids often contain ethylene glycol as protec-tion against freezing. About 26 percent of all the ethyleneglycol made in the United States is used for some kind ofcooling or antifreeze application.

The largest single use of ethylene glycol today is in themanufacture of a plastic called polyethylene terephthalate(PET). PET’s primary application is in the manufacture ofplastic bottles, an application that accounts for about a thirdof all the ethylene glycol made in the United States. Largeamounts of PET are also used in the manufacture of polyesterfibers and films. Some additional uses of the compoundinclude:

• As a humectant (a substance that attracts moisture) inkeeping some food, tobacco, and industrial productsdry;

• As a solvent in some paints and plastics;

Interesting Facts

• In 1996, 60 children diedin Haiti of ethylene glycolpoisoning after drinkingcough syrup made in

China that hadaccidentallybeen contaminatedwith the compound.


ETHYLENE GLYCOL

• In the dyeing of leathers and textiles;

• In the manufacture of printing inks, wood stains, inkfor ball-point pens, and adhesives;

• In the production of artificial smoke and fog for thea-trical productions;

• As a stabilizer in the soybean-based foam sometimesused to extinguish industrial fires; and

• In the manufacture of specialized types of explosives.

Ethylene glycol poses a number of potential health andsafety hazards. It is very flammable and highly toxic. Inges-tion of the compound may cause nausea, vomiting, abdom-inal pain, weakness, convulsions, and cardiac problems.Higher doses can result in severe kidney damage that leadsto death.


‘‘Ethylene Glycol.’’ Environmental Protection Agency.http://www.epa.gov/ttn/atw/hlthef/ethy gly.html (accessed onOctober 7, 2005).

‘‘Ethylene Glycol.’’ National Safety Council.http://www.nsc.org/library/chemical/Ethylen1.htm (accessedon October 7, 2005).

‘‘Medical Management Guidelines (MMGs) for Ethylene Glycol.’’Agency for Toxic Substances and Disease Registry.http://www.atsdr.cdc.gov/MHMI/mmg96.html (accessed onOctober 7, 2005).

Words to Know

CATALYST A material that increasesthe rate of a chemical reactionwithout undergoing any changein its own chemical structure.

HUMECTANT A substance that attractsmoisture more easily than other substances.

MISCIBLE able to be mixed; especially appliesto the mixing of one liquid with another.


ETHYLENE GLYCOL

OTHER NAMES:Epoxyethane; oxirane

FORMULA:(CH2)2O


oxygen

COMPOUND TYPE:Cyclic ether (organic)

STATE:Gas





ethyl alcohol,acetone, benzene,

and ether

Ethylene Oxide

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OVERVIEW

Ethylene oxide (ETH-ih-leen OK-side) is a flammable, color-less gas with the odor of ether. The gas is a cyclic compound,consisting of a ring of two carbon atoms and one oxygen atom.Each carbon atom also has two hydrogen atoms attached to it.Ethylene oxide was first prepared in 1859 by French chemistCharles Adolphe Wurtz (1817–1884). Wurtz produced the com-pound by reacting ethylene chlorhydrin (2-chloroethanol;ClCH2CH2OH) with an inorganic base (such as sodium hydroxide;NaOH), a process that remained the principle method for prepar-ing the gas for more than a century. After World War II (1939–1945), a method was discovered for the direct oxidation ofethylene gas that is more efficient than the chlorhydrin process.

Ethylene oxide is a very unstable compound that catchesfire or explodes readily and must be handled with the great-est care. Nonetheless, it is an important industrial chemicaland ranks nineteenth by volume among chemicals producedin the United States. Its primary use is in the manufacture ofother organic compounds.

H H

C

O

C

HH


HOW IT IS MADE

The chlorhydrin process for making ethylene oxide hasbeen replaced commercially by the direct oxidation of ethy-lene gas. Oxidation takes place at temperatures of 200�C to300�C (392�F to 572�F) over a silver catalyst. The formula forthis reaction is 2CH2=CH2 + O2 ! 2CH2CH2O.The yield pro-duced by direct oxidation is slightly less than that producedby the chlohydrin process, but the amount of chlorine wastedby the latter method outweighs the slight difference inefficiency of production.


The largest single use of ethylene oxide is in the manu-facture of ethylene glycol (CH2OHCH2OH), which itself isused as an antifreeze and raw material for the productionof plastics. About 60 percent of all the ethylene oxide pro-duced is used for this purpose. The compound is also used tomake higher glycols, such as diethylene and triethyleneglycol (CH2OHCH2OCH2CH2OH and CH2OHCH2OCH2CH2OCH2-

CH2OH). The second most important application of ethyleneoxide is in the synthesis of ethyoxylates and ethanolamines,substances used in the production of synthetic detergents.These substances act as surfactants in detergents—substances

Ethylene Oxide. Black atomsare carbon; white atoms are

hydrogen; red atom is oxygen.White sticks show single bonds.P U B L I S H E R S R E S O U R C E G R O U P


ETHYLENE OXIDE

that reduce the surface tension between two materials andimprove the lathering ability of a cleaner.

Ethylene oxide also has a number of other importantindustrial uses, although the quantity used for such purposesis small compared to the uses mentioned above. For example,it is used as a rocket propellant because of its tendency todecompose easily with the release of large amounts ofenergy. It is also used as a sterilizing medium, particularlyfor the sterilization of surgical instruments and consumerproducts, such as spices and cosmetics. The compound is alsoused as a demulsifier in the petroleum industry. A demulsi-fier is a material that aids in the separation of the compo-nents of complex mixtures, like those handled in the proces-sing of petroleum. Ethylene oxide is also used as a fumigant,which is a gas used to kill insects and other pests.

A number of health hazards are associated with exposureto ethylene oxide. It is a skin, eye, and respiratory systemirritant, causing symptoms such as dizziness, nausea, head-ache, convulsions, blistering of the skin, coughing, tightnessof the chest, difficulty in breathing, and blurred vision. Long-term exposure to the gas may produce more serious healthconsequences, such as damage to the nervous system, muscu-lar weakness, paralysis of the peripheral nerves, impairedthinking, loss of memory, and severe skin irritation. Ethylene

Interesting Facts

• Ethylene oxide’s instabilityis caused by its unusualthree-atom ring structure.A ring with three atoms isa stressed arrangementthat breaks apart witheven moderate amounts ofstress.

• A number of industrialaccidents have beencaused during thepreparation, transportation,

storage, and use ofethylene oxide. It is one ofthe most hazardous of thetop twenty-five chemicalsproduced in the UnitedStates.

• In 2004, some 3.77 millionmetric tons (4.15 millionshort tons) of ethyleneoxide were produced inthe United States.


ETHYLENE OXIDE

oxide is believed to be responsible for spontaneous abortions,genetic damage, and the development of some types of cancer,primarily cancer of the blood (leukemia).


Buckles, Carey, et al. Ethyleneoxide. 2nd ed. Celanese Ltd., TheDow Chemical Company, Shell Chemical Company, Sunoco,Inc., and Equistar Chemicals, LP. Also available online athttp://www.ethyleneoxide.com/html/introduction.html(accessed January 3, 2006).

Environment Canada, Health Canada. Ethylene Oxide. Ottawa:Environment Canada, 2001.

‘‘Ethylene Oxide.’’ OSHA Fact Sheet.http://www.osha.gov/OshDoc/data_General_Facts/ethyleneoxide factsheet.pdf (accessed on December 27, 2005).

‘‘Ethylene Oxide Health and Safety Guide.’’ IPCS InternationalProgramme on Chemical Safety.http://www.inchem.org/documents/hsg/hsg/hsg016.htm(accessed on December 27, 2005).

‘‘ToxFAQsTM for Ethylene Oxide.’’ Agency for Toxic Substancesand Disease Registry.http://www.atsdr.cdc.gov/tfacts137.html (accessed on December27, 2005).

See Also Ethylene; Ethylene Glycol

Words to Know


ETHER An organic compound in which oneoxygen atom is bonded to two carbonatoms: - C - O - C. Ethylene oxide is thesimplest cyclic ether.


ETHYLENE OXIDE

OTHER NAMES:L-glutamic acid;

vitamin Bc; vitaminB9; vitamin M

FORMULA:C19H19N7O6


nitrogen, oxygen


STATE:Solid


MELTING POINT:Decomposes at 250�C

(480�F)


SOLUBILITY:Very slightly solublein water and methylalcohol; insoluble in

ethyl alcohol andacetone

Folic Acid

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OVERVIEW

Folic acid (FOH-lik AS-id) is a member of the B vitamingroup, which is essential for the production of proteins andnucleic acids. In pure form, it is a tasteless, odorless, orange-to-yellow crystalline substance that is destroyed by heat orexposure to light. The compound occurs in three similarforms with comparable biological activity. Only one of itsforms, l-pteroylglutamic acid, is made synthetically (in alaboratory). Folic acid is sometimes referred to in its ionicform as folate, which differs from folic acid only in theabsence of a single hydrogen atom in its structure. The termfolate is also used for a group of compounds structurallysimilar to folic acid.

Credit for the discovery of the nutritional significance offolic acid is often given to English medical researcher LucyWills (1888–1964). In the early 1920s, Wills discovered thatanemia in pregnant women could be prevented if theyincluded yeast in their diets. Anemia is a condition in whichthe blood contains too few red blood cells. Wills located

N N

NH H

C

C

C C N

HH

C CC

C C

CH2

H2N

O

C N

H OHOH

C

HCC

C

CH2

CO

H

HO

C OC

N


a specific compound in yeast that produced this effect andcalled it the ‘‘Wills Factor.’’ At about the same time, otherresearch teams were discovering a similar compound thatprevented anemia in monkeys, chicks, and other animals.One team, led by American researcher William J. Darby(1913–2001) called their anti-anemia factor ‘‘vitamin M,’’(for monkeys) and a third research team discovered a similarfactor that prevented anemia in chicks and called it vitaminBc (for chicks). Folic acid was finally isolated and identifiedin 1941 by American researcher Henry K. Mitchell (1917– ),who suggested the modern name of folic acid for the com-pound. He chose the name because the compound was abun-dant in leafy vegetables and the Latin word for leaf isfolium.

By the 1980s, scientists had produced evidence that theaddition of folic acid in the diets of pregnant women canprevent birth defects such as spina bifida, a condition inwhich a baby’s spinal column fails to close properly whiledeveloping inside the mother’s womb. Researchers hadlearned how to fortify foods with folic acid in the 1970s,but manufacturers did not actually begin to do so until thelate 1990s, when the U.S. government began requiring com-panies to supplement cereals, breads, and other grain-basedproducts with the vitamin.

Folic Acid. Red atoms areoxygen; white atoms arehydrogen; black atoms

are carbon; and blue atomsare nitrogen. Striped sticks

indicate a benzene ring.P U B L I S H E R S R E S O U R C E G R O U P


FOLIC ACID

HOW IT IS MADE

The body produces some folic acid and obtains theremainder through food and dietary supplements. In thebody, folic acid is produced by bacteria in the large intestine,absorbed in the small intestine, and stored in the liver. Thel-pteroylglutamic acid form of folic acid is also producedsynthetically.


The sole use of folic acid is as a nutrient in animal bodies.It is used in the synthesis of methionine, an amino acid usedin the formation of proteins and nucleic acids. A deficiencyof folic acid can produce various symptoms, including ulcersin the stomach and mouth, slowed growth, and diarrhea. Italso results in a medical condition known as megaloblasticanemia, in which a person’s body produces red blood cellsthat are larger than normal.

Adequate amounts of folic acid are especially importantin fetal development, during the first eight weeks of lifefollowing fertilization. The compound is essential to promotenormal development of the fetal nervous system. Folic aciddeficiencies in the mother during this period may result inneural tube defects such as spina bifida or anencephaly, acondition in which the fetus’ brain and skull fail to developnormally. The U.S. Centers for Disease Control and Preven-tion recommend that pregnant women take 600 microgramsof folic acid daily to avoid such problems.

Some evidence suggests that folic acid supplements mayalso reduce the risk of heart disease; strokes; and cervicaland colon cancers. Folic acid is generally nontoxic, and side

Interesting Facts

• The recommended dailydose of folic acid foradults is 400 microgramsper day. The best sourcesof the vitamin are fortified

cereals and grain products,beef liver, black-eyed peas,spinach, avocado (raw), andeggs.


FOLIC ACID

effects associated with its use are very rare. In unusual cases,allergic reactions to the compound have been reported.


‘‘Folate.’’ PDRhealth.http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/fol_0110.shtml (accessed on October 10, 2005).

Folate (Folacin, Folic Acid). Ohio State University Extension FactSheet.http://ohioline.osu.edu/hyg fact/5000/5553.html (accessed onOctober 10, 2005).

‘‘Folic Acid.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/pims/pharm/folicaci.htm(accessed on October 10, 2005).

‘‘Folic Acid Fortification.’’ U.S. Food and Drug Administration.http://vm.cfsan.fda.gov/~dms/wh folic.html (accessed on October10, 2005).

‘‘Vitamins: The Quest for Just the Right Amount.’’ Harvard Health

Letter. (June 2004): 1.

Words to Know




FOLIC ACID

OTHER NAMES:Methanal;

oxomethylene;oxomethane;

methylene oxide;formic aldehyde

FORMULA:HCHO


oxygen

COMPOUND TYPE:Aldehyde (organic)

STATE:Gas




SOLUBILITY:Very soluble in water,

alcohol, ether, andbenzene

Formaldehyde

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OVERVIEW

Formaldehyde (for-MAL-duh-hide) is a colorless, flam-mable gas with a strong, pungent odor that tends to poly-merize readily. Polymerization occurs when individualmolecules of formaldehyde combine with each other tomake very large molecules called polymers. Over 4 billionkilograms (10 billion pounds) of formaldehyde were pro-duced in the United States in 2004, the vast majority ofwhich was used in the production of plastics and otherpolymers. To make handling and shipping easier and safer,the compound is usually provided as a 37 percent solution offormaldehyde in water to which has been added an addi-tional 15 percent of methanol (methyl alcohol) to preventpolymerization.

Formaldehyde was first produced accidentally in 1859by the Russian-French chemist Alexander MikhailovichButlerov (1828–1886). It was first synthesized in 1867 by theGerman chemist August Wilhelm von Hofmann (1818–1892)who was not, however, able to collect the compound in

C

O

HH


pure form. That step was accomplished by German chemistFriedrich August Kekule (1829–1896) in 1892.

HOW IT IS MADE

Formaldehyde occurs naturally in the atmosphere at aconcentration of about 10 parts per billion (0.000 001%)partly as a by-product of plant and animal metabolism, andpartly as a product of the reaction of sunlight with methane(CH4), a much more abundant component of the air. At suchlow concentrations, it is not a natural source of the compoundfor commercial or industrial uses and is produced insteadby the oxidation of methanol (methyl alcohol; CH3OH) orgases extracted from petroleum (such as methane) over acatalyst of silver, copper, or iron with molybdenum oxide.


By far the most important application of formaldehyde isin the production of polymers and other organic chemicals.

Formaldehyde. Red atom isoxygen; white atoms are

hydrogen; and black atom iscarbon. Gray sticks indicatedouble bonds. P U B L I S H E R S



FORMALDEHYDE

About one-quarter of commercial-use formaldehyde is usedeach year to make a family of polymers known as urea-formaldehyde resins, which are used to make dinnerware,particle board, fiber board, plywood, flexible foams, andinsulation. Another 16 percent goes to the production ofphenol-formaldehyde resins, with applications in moldedand cast plastics, adhesives and bonding materials, laminat-ing materials, brake linings, chemical equipment, machinehousing, and a host of other applications. Smaller amountsof formaldehyde are used to make a variety of importantchemicals including 1,4-butanediol, methylene diisocyanate,pentaerythritol, and hexamethylenetetramine. Other applica-tions include use in controlled release fertilizers, in theproduction of nitroparaffin derivatives, in the treatment oftextiles, and in the preservation of biological specimens. Thelast of these uses is probably well known to biology students;its use depends on the fact that formaldehyde kills mosttypes of bacteria and can be used, therefore, to keep biologi-cal materials from decaying.

Formaldehyde poses a number of health hazards tohumans and other animals. It may cause difficulty in breath-ing, headaches, fatigue, and lowered body temperature. Athigh levels of concentration or over long periods of exposure,formaldehyde can induce coma and death. Chronic exposureto formaldehyde is thought to be carcinogenic, producingtumors in the nose, throat, and respiratory system. Peoplewho work in factories where formaldehyde is used are atgreatest risk for formaldehyde poisoning.

Formaldehyde is now known to be a potentially seriousindoor air pollutant. So many products in a home contain

Interesting Facts

• Formaldehyde was oneof the first organiccompounds to have beendiscovered in outerspace.

• When some vegetables,such as cabbage andbrussel sprouts arecooked, they emit smallamounts of formaldehyde.


FORMALDEHYDE

formaldehyde that significant levels of the compound mayaccumulate in a house. The primary sources of the formalde-hyde are pressed wood products such as plywood and particle-board; furnishings; wallpaper; and durable press fabrics.


‘‘About Formaldehyde.’’ Formaldehyde Council.http://www.formaldehyde.org/about_what.html (accessed onOctober 10, 2005).

‘‘Formaldehyde (Methyl Aldehyde) Fact Sheet.’’ Australian Government; Department of the Environment and Heritage.http://www.npi.gov.au/database/substance info/profiles/45.html (accessed on October 10, 2005).

Gullickson, Richard. ‘‘Reference Data Sheet on Formaldehyde.’’Meridian Engineering & Technology.http://www.meridianeng.com/formalde.html (accessed onOctober 10, 2005).

‘‘An Update on Formaldehyde 1997 Revision.’’ U.S. Consumer Product Safety Commission.http://www.epa.gov/iaq/pubs/formald2.html (accessed onOctober 10, 2005).

See Also Urea

Words to Know



METABOLISM A process that includes all ofthe chemical reactions that occur in cells

by which fats, carbohydrates, and othercompounds are broken down to produceenergy and the compounds needed tobuild new cells and tissues.

POLYMER A compound consisting of verylarge molecules made of one or twosmall repeated units called monomers.


FORMALDEHYDE

OTHER NAMES:D-Fructose; fruit

sugar

FORMULA:C6H12O6


oxygen

COMPOUND TYPE:Carbohydrate

(organic)

STATE:Solid



decomposes


SOLUBILITY:Very soluble in waterand acetone; solublein ethyl alcohol and

methyl alcohol

Fructose

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OVERVIEW

Fructose (FROOK-tose) is a white crystalline solid foundin honey and certain fruits and vegetables. It is the sweetestof the common sugars. Fructose is a carbohydrate, an organiccompound in which five of the six carbon atoms are arrangedin a ring to which are attached the hydrogen atoms andhydroxy (-OH) groups that make up the molecule. It is classi-fied as a monosaccharide (‘‘one sweet substance’’), in contrastto sucrose, common table sugar, which is classified as a dis-accharide (‘‘two sweet substances’’). Molecules of sucrose con-sist of two rings rather than the one ring found in fructose.

HOW IT IS MADE

Fructose is produced commercially by the hydrolysis ofbeet sugar or inulin, a polysaccharide found in the roots of anumber of plants, including dahlias, Jerusalem artichokes,and chicory. Hydrolysis is the process by which a materialis broken down into simpler elements by reacting it with

C

C

HO

HOH

O

H

H

H

H

OH

OHC C

CH

COH

H


water. A polysaccharide is a carbohydrate with many simplesugar groups attached to each other. After hydrolysis of thebeet sugar, or inulin, the resulting mixture is treated withlime (calcium oxide; CaO) to extract the fructose. It is thenrefined by removing impurities left from the preparationprocess.


Virtually the only important use of fructose is as a sweet-ener and preservative in a number of food products. In mostcases, it is now used in the form of a substance known ashigh-fructose corn syrup (HFCS). HFCS was first introducedin the 1970s after scientists at the Clinton Corn ProcessingCompany in Clinton, Iowa, developed a method of convertingthe sugar in corn into glucose and fructose. The Clinton

Fructose. Red atoms areoxygen; white atoms are

hydrogen; and black atomsare carbon. P U B L I S H E R S



FRUCTOSE

process is relatively complicated. The polysaccharides in cornare first converted to glucose, and the glucose is then treatedwith enzymes that convert it to a thick syrup consisting ofroughly half glucose and half fructose. From a nutritionalstandpoint, HFCS is very similar to sucrose, common tablesugar, but it is less expensive to produce than sucrose and ismore convenient to use in many instances.

High-fructose corn syrup has become one of the greatsuccess stories in the recent history of food processing in theUnited States. It has replaced sucrose in many applications,including nearly all soft drinks and fruit beverages, and inmany jams and jellies, cookies, gum, baked goods, and otherprocessed foods. Consumption of HFCS in the United Stateshas increased from about 2 million metric tons (2.2 millionshort tons) in 1980 to just over 8 million metric tons(8.8 million short tons) in 2000.

When high-fructose corn syrup was first introduced,experts in nutrition did not anticipate that any health pro-blems would be associated with the new product. After all,both fructose and glucose are naturally occurring substancesthat humans have been consuming for millennia. They arenot so sure any more. Some evidence suggests that fructoseis metabolized differently in the body than is glucose. It isnot converted to energy as efficiently and may actually actmore like a fat than like a sugar. Since few studies have beenconducted on the ultimate chemical fat of fructose in thebody, the nutritional value of HFCS is still the subject ofsome controversy among experts.

Interesting Facts

• Sucrose is a disaccharidethat consists of one mole-cule of glucose joined toone molecule of fructose.The first step in the diges-tion of sucrose is thehydrolysis of the molecule,resulting in the formation

of one molecule of glucoseand one molecule of fruc-tose. These compounds arethe primary materials usedby the human body in pro-ducing the energy neededto stay alive and grow.


FRUCTOSE

The dangers of consuming HFCS are apparent for at leastone group of people, those who lack the enzyme needed tometabolize fructose properly. Individuals with this geneticdisorder may develop serious reactions if exposed to even avery small amount of fructose, reactions that include sweat-ing, nausea, vomiting, confusion, abdominal pain, and, inextreme cases, convulsion and coma. Fortunately, this dis-order is quite rare, affecting one person in about every twentythousand individuals. For those with the disorder, however,care must be used in the kinds of sweeteners included inthe diet.


Basciano, Heather, Lisa Federico, and Khosrow Adeli. ‘‘Fructose,Insulin Resistance, and Metabolic Dyslipidemia.’’ Nutrition

and Metabolism. (Electronic journal)http://www.nutritionandmetabolism.com/content/2/1/5 (accessedon October 10, 2005).

Ophardt, Charles E. ‘‘Fructose.’’ Elmhurst College.http://www.elmhurst.edu/~chm/vchembook/543fructose.html(accessed on October 10, 2005).

Squires, Sally. ‘‘Sweet but Not So Innocent?’’ Washington Post.

(March 11, 2003): HE01. Available online athttp://www.washingtonpost.com/ac2/wp dyn/A8003 2003Mar10?language=printer (accessed on October 10, 2005).

‘‘What Do We Know about Fructose and Obesity?’’ The International Food Information Council.http://www.ific.org/foodinsight/2004/ja/fructosefi404.cfm(accessed on October 10, 2005).

See Also Glucose; Sucrose

Words to Know

HYDROLYSIS The process by which acompound reacts with water to formtwo new compounds


FRUCTOSE

OTHER NAMES:Benzene

hexachloride; BHC;HCCH; HCH; TBH

FORMULA:C6H6Cl6


chlorine

COMPOUND TYPE:Chlorinated aromatic


STATE:Solid




SOLUBILITY:Insoluble in water;soluble in absolute

alcohol, chloroform,and ether

Gamma-1,2,3,4,5,6-Hexachlorocyclo-hexane

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OVERVIEW

Gamma-1,2,3,4,5,6-hexachlorocyclohexane (GAM-uh onetwo three four five six HEK-sa-KLOR-oh-SYE-kloh-HEK-sane)exists in four isomeric forms. Isomers are two or more formsof a chemical compound with the same molecular formula,but different structural formulas and different chemical andphysical properties. The isomer of greatest commercial inter-est is called the gamma (g) isomer and is also known aslindane. It is sold commercially in more than a hundredcommercial products under trade names such as 666, Afri-cide, Agrocide, Aparasin, Arbitex, Ben-Hex, Bentox, Devoran,Entomoxan, Exagamma, Forlin, Gamaphex, Gammalin, Gam-mex, Gexane, Hexachloran, Isotox, Jacutin, Kwell, Lindafor,Lindatox, Lin-O-Sol, Lintox, Streunex, Tri-6, and Vitron.

Gamma-1,2,3,4,5,6-hexachlorocyclohexane is normallyavailable as a white to yellowish powder or crystalline solidwith a musty odor. Its color, odor, melting point, and othercharacteristics differ depending on the relative amount of thefour isomers present in the final product. Gamma-1,2,3,4,5,

ClH

Cl

H

ClH

ClH

H

Cl

ClH

CC C

C CC


6-hexachlorocyclohexane is non-flammable and stable in thepresence of heat, light, strong acids, and carbon dioxide. Thecompound has two primary commercial uses: as a pesticide inagriculture and as a treatment for head lice, scabies, and otherexternal parasites.

HOW IT IS MADE

Gamma-1,2,3,4,5,6-hexachlorocyclohexane is made bytreating benzene (C6H6) with chlorine gas. In the process,each of the six hydrogen atoms in the benzene ring isreplaced by a chlorine atom, resulting in the formation of afully chlorinated benzene ring. That is, all of the original sixhydrogen atoms have been replaced by chlorine atoms.

Gamma 1,2,3,4,5,6

Hexachlorocyclohexane.

White atoms are hydrogen;black atoms are carbon; and

green atoms are chlorine.P U B L I S H E R S R E S O U R C E G R O U P


GAMMA 1,2,3,4,5,6 HEXACHLOROCYCLOHEXANE


About 80 percent of all g-1,2,3,4,5,6-hexachlorocyclohex-ane produced worldwide is used in agriculture, especially fortreating soil and seeds. The wood and timber industries alsouse the product to protect trees from insects that attackthem. In some places, g-1,2,3,4,5,6-hexachlorocyclohexaneis used as a spray to control the spread of mosquitoes. Veter-inarians sometimes use the compound to treat or preventfleas and other external parasites on animals. Gamma-1,2,3,4,5,6-hexachlorocyclohexane is also a major ingredientof products used to treat head lice, scabies, and similar peststhat infest body hair.

Gamma-1,2,3,4,5,6-hexachlorocyclohexane is a member ofthe family of compounds known as the organochlorides,organic compounds that include one or more atom of chlor-ine in their molecular structure. The family also includes anumber of other well-known products, such as DDT, dieldrin,aldrin, endrin, dinoseb, and chlordane. These compounds killpests by attacking and incapacitating their nervous systems.Unfortunately, they have somewhat similar effects on thenervous systems of higher animals, including humans. Manyof these organochlorides have been banned in commercialapplications and many nations around the world.

The status of g-1,2,3,4,5,6-hexachlorocyclohexane is stilla matter of some controversy. It is banned for medicinal usesin many countries of the world, including Bangladesh, Belize,Bolivia, Brazil, Bulgaria, Chad, Denmark, Ecuador, Egypt,Finland, Guatemala, Honduras, Hong Kong, Hungary, Indonesia,Japan, Kuwait, Mozambique, New Zealand, The Netherlands,Nicaragua, Paraguay, the Republic of Korea, Singapore,Sweden, Taiwan, and Yemen. Its use is still permitted in theUnited States, although it has been banned as a known carcino-gen in the state of California. The product has also been bannedfor some or all agriculture applications in more than 50 nations.

Gamma-1,2,3,4,5,6-hexachlorocyclohexane poses a healthhazard to humans if ingested, inhaled, or deposited on theskin. It may cause skin irritation or rashes, nausea andvomiting, nervousness or irritability, accelerated heartbeat,convulsions or seizures, and dizziness or clumsiness. In rarecases, the ingestion of the compound has resulted in aperson’s death. It has also been classed as a likely carcinogenby the U.S. Environmental Protection Agency. The compound



has been ranked in the top 10 percent among the mosthazardous chemicals in ten out of eleven systems for makingsuch rankings. It is ranked number thirty-two on the U.S.Agency for Toxic Substances and Disease Registry’s list of275 ‘‘priority’’ hazardous chemicals.

In spite of the apparent risk that g-1,2,3,4,5,6-hexachlo-rocyclohexane poses to human health and the environment,its use is still permitted for many applications in the UnitedStates. A number of consumers’ groups are currently work-ing, however, to have the compound’s use totally or partiallybanned.


‘‘Drug Information for Gamma Benzene Hexachloride.’’ Drugs.com.http://www.drugs.com/cons/Gamma_benzene_hexachloride.html(accessed on October 10, 2005).

‘‘Hexachlorocyclohexane (Mixed Isomers).’’ International LabourOrganization.http://www.oit.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc04/icsc0487.htm (accessed onOctober 10, 2005).

‘‘Lindane.’’ IPCS International Programme on Chemical Safety.http://www.inchem.org/documents/hsg/hsg/hsg054.htm(accessed on October 10, 2005).

‘‘Lindane Education and Research Network.’’ National PediculosisAssociation.http://www.headlice.org/lindane/ (accessed on October 10,2005).



OTHER NAMES:Gelatine



oxygen, nitrogen, andothers

COMPOUND TYPE:Not applicable

STATE:Solid

MOLECULAR WEIGHT:Not applicable



SOLUBILITY:Soluble in hot water

and glycerol;insoluble in mostorganic solvents

Gelatin

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OVERVIEW

Gelatin (JELL-ah-tin) is a mixture, not a compound. Mix-tures differ from compounds in a number of important ways.The parts that make up a mixture are not chemically com-bined with each other, as they are in a compound. Also,mixtures have no definite composition, but consist of vary-ing amounts of the substances from which they are formed.Gelatin is a mixture of water-soluble proteins with highmolecular weights. It typically occurs as a brittle solid inthe form of colorless or slightly yellow flakes or sheets, orin powder form, with virtually no taste or odor. It absorbs upto ten times its own weight when mixed with cold water anddissolves in hot water. When a solution of gelatin in hotwater is cooled, it takes the form of a gel, a jelly-like materialperhaps most commonly seen as the popular dessert calledJELL-OTM. Gelatin is also available in a number of othercommercial forms, such as Knox GelatinTM, Puragel�, andGelfoam�. Gelatin has been known to humans for manycenturies, but it was not widely marketed until the late


1890s. Its name comes from the Latin word gelatus, whichmeans ‘‘frozen.’’

HOW IT IS MADE

Gelatin is made by boiling animal parts with high pro-tein content, such as skin, ligaments, tendons, cartilage, andbones. The boiling process breaks down molecular bondsbetween individual collagen strands in the animal tissue.Collagen is a structural protein found in bone, cartilage,and connective tissue. The collagen formed by this processcan be further disintegrated through additional boiling witheither acid or alkali. Type A gelatin is produced when col-lagen is boiled in an acidic solution, and type B gelatin isproduced by boiling collagen in an alkaline solution.

Most of the animal parts used to make gelatin come fromcattle and pigs and are left over from meat and leatherprocessing. Gelatin can also be made from fish. One of theoldest forms of gelatin is isinglass, made from the swimbladders of fish. Jewish and Muslim dietary laws prohibitbelievers from eating pork, so some gelatin is made withoutpig parts. Vegetarians and vegans do not eat any animalproducts, so gelatin manufacturers also make similar pro-ducts using vegetable carbohydrates, such as agar and pectin.These vegetarian gelatins are not true gelatin, which isalways made from animal proteins.


People discovered gelatin centuries ago and experimen-ted with various uses for it. In the early 1800s, for example,gelatin was included in the food served to French soldiers asa source of dietary proteins. In the 1890s, Knox GelatinTM

was sold as a cure for dry fingernails. Manufacturers claimedthat dry fingernails were caused by a lack of protein and thateating gelatin would cure the condition. No scientific evi-dence exists for that claim, but Knox GelatinTM becamepopular among consumers nonetheless.

In 1900, the Genesee Pure Food Company began sellingflavored gelatin under the name JELL-OTM. In the early 1900s,the company began distributing booklets containing recipesusing JELL-OTM, eventually giving out more than 15 millionsuch booklets. JELL-OTM eventually became one of the most


GELATIN

popular desserts in the United States and other countries. It hasbeen used to make a variety of pleasant tasting, attractivelooking desserts molded into many different shapes. Cooks havecombined gelatin with water, milk, soft drinks, other liquids,whipped toppings, or mayonnaise to change its taste andtexture. The product is often served with fruits or vegetablesas a salad. Gelatin is also combined with marshmallows, jelly-beans, jelly, yogurt, gummy candies, ice cream, and margarineto produce desserts of many textures and flavors. The product issometimes recommended as a fat substitute because it providesvolume in a diet without adding many calories. Some peopleinclude gelatin products in their diets as a way of increasingprotein intake. Although plain gelatin is almost entirelyprotein, it actually has relatively little nutritional value.

Gelatin has many other uses, including:

• As a raw material for the manufacture of capsules andgels in the production of drugs;

• As a way of holding silver halide (silver bromide andsilver iodide) crystals in place on photographic filmsand plates;

• In the manufacture of blocks used to determine thepossible effects of various types of ammunition onhuman flesh;

Interesting Facts

• Before refrigeratorsbecame common, gelatinwas used to keep foodsfresh and attractive. Packinga food in gelatin preventsoxygen from reacting withthe food and causingspoilage.

• Synchronized swimmerssometimes use gelatin tohold their hair in placeduring performances.

• Aspic is a clear jelly oftenmade with gelatin. It is acomponent of manyelegant dishes, one ofwhich, ‘‘Oeufs de caile enaspic et caviar’’ (Quail eggsin aspic with caviar), wasserved in first class on thedoomed steam ship Titanic

in 1912.


GELATIN

• As a binder that holds sand on sandpaper or to makecertain types of paper products (such as playing cards)bright and shiny;

• As an additive in various types of cosmetics and skintreatments;

• In the manufacture of meshes used in the repair ofwounds and in the production of artificial heart valves;

• In the production of certain types of cement;

• For the manufacture of light filters used in theatricalproductions and for other specialized purposes;

• As a culturing medium for bacteria;

• As a stabilizer and thickener for certain types of foods,especially ice cream and some other dairy products;

• In the manufacture of printing inks;

• As an additive in the production of plastics and rubberproducts.


‘‘Gelatin.’’ WholeHealthMC.com.http://www.wholehealthmd.com/refshelf/substances_view/1,1525,10151,00.html (accessed on December 22, 2005).

‘‘A History of JELL OTM Brand.’’ Kraftfoods.com.http://www.kraftfoods.com/jello/main.aspx?s=&m=jlo_history(accessed January 4, 2006).

‘‘The Jell O Museum.’’ The Genesee Pure Food Co.http://www.jellomuseum.com/#Page1. (accessed on December22, 2005).

Words to Know


MIXTURE A collection of two or moreelements and/or compounds with nodefinite composition.

PROTEIN A large, complex compoundmade of long chains of amino acids.Proteins have a number of essentialfunctions in living organisms.


GELATIN

‘‘What Exactly Is Jell O Made From?’’ How Stuff Works.http://home.howstuffworks.com/question557.htm (accessedon December 22, 2005).

‘‘What Is Gelatin.’’ PB Leiner.http://www.gelatin.com/ (accessed on December 22, 2005).

Wyman, Carolyn. JELL O: A Biography. Fort Washington, PA:Harvest Books, 2001.

See Also Collagen


GELATIN

OTHER NAMES:Dextrose; grape

sugar; corn sugar;blood sugar

FORMULA:C6H12O6


oxygen

COMPOUND TYPE:Carbohydrate

(organic)

STATE:Solid



decomposes


SOLUBILITY:Very soluble in water;

slightly soluble inalcohol; insoluble in


Glucose

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OVERVIEW

Glucose (GLOO-kose) is a simple sugar used by plants andanimals to obtain the energy they need to stay alive and togrow. It is classified chemically as a monosaccharide, a com-pound whose molecules consist of five- or six-memberedcarbon rings with a sweet flavor. Other common examplesof monosaccharides are fructose and galactose. Glucoseusually occurs as a colorless to white powder or crystallinesubstance with a sweet flavor. It consists in two isomericforms known as the D configuration and the L configuration.Dextrose is the common name given to the D conformation ofglucose.

Credit for the discovery of glucose is often given to theGerman chemist Andreas Sigismund Marggraf (1709–1782).In 1747, Marggraf isolated a sweet substance from raisinsthat he referred to as einer Art Z�cker (a kind of sugar) thatwe now recognize as glucose. More than 60 years later, theGerman chemist Gottlieb Sigismund Constantine Kirchhof(1764–1833) showed that glucose could also be obtained from

O

HO OH

OH

OH

HO

CC C

C CH

H

H

H

H

H

H

C


the hydrolysis of starch and that starch itself was nothing

other than a very large molecule (polysaccharide) composed

of many repeating glucose units. The molecular structure

for glucose was finally determined in the 1880s by German

Glucose. Red atoms areoxygen; whjte atoms are




GLUCOSE

chemist Emil Fischer (1852–1919), part of the reason for

which he was awarded the 1902 Nobel Prize in chemistry.

HOW IT IS MADE

Glucose is synthesized naturally in plants and some sin-gle-celled organisms through the process known as photo-synthesis. In this process, sunlight catalyzes the reactionbetween carbon dioxide and water that results in the forma-tion of a simple carbohydrate (glucose) and oxygen. The over-all reaction can be summarized by a rather simple chemicalequation:

6CO2 + 6H2O ! C6H12O6 + 6O2

However, photosynthesis actually involves a number ofcomplex reactions that occur in two general phases, the lightreactions and the dark reactions.

Glucose is produced commercially through the steamhydrolysis of cornstarch or waste products containing cellu-lose (a large molecule composed of glucose units) using adilute acid catalyst. The product thus obtained is typicallynot very pure, but is contaminated with maltose (a disacchar-ide consisting of two molecules of glucose joined to eachother) and dextrins (larger molecules consisting of a numberof glucose units joined to each other).


Glucose is the primary chemical from which plants andanimals derive energy. In cells, glucose is broken down in acomplex series of reactions to produce energy with carbondioxide and water as byproducts.

Interesting Facts

• The name glucose comesfrom the Greek wordgleucos for ‘‘sweet wine.’’


GLUCOSE

Glucose also has a number of commercial uses, nearly allof them related to the food processing business. It is used inthe production of confectionary products; chewing gum; softdrinks; ice creams; jams, jellies, and fruit preparations; babyfoods; baked products; and beers and ciders. A relatively smallamount is used for non-food purposes, primarily in the produc-tion of other organic chemicals, such as citric acid, the aminoacid lysine, insulin, and a variety of antibiotics.

The most important health problem associated withglucose is diabetes. Diabetes is a medical condition thatdevelops when the body either does not produce adequateamounts of insulin or cannot use that compound properly.Insulin is a hormone that controls the metabolism of glu-cose in the body. If glucose is not metabolized properly, aperson’s body acts as if it is ‘‘starving.’’ Symptoms of dia-betes include excessive hunger, weight loss, and exhaus-tion. If left untreated, the condition can result in comaand death. Diabetics must have an artificial source of insu-lin (usually from injections) and watch their diets to keepthese symptoms under control.


‘‘All about Diabetes.’’ American Diabetes Association.http://www.diabetes.org/about diabetes.jsp (accessed on October 10, 2005).

Words to Know


HYDROLYSIS The process by which a com-pound reacts with water to form two newcompounds.

ISOMERS Two or more forms of a chemicalcompound with the same molecularformula, but different structural formulas

and different chemical and physicalproperties.

METABOLISM A process that includes allof the chemical reactions that occur incells by which fats, carbohydrates, andother compounds are broken down toproduce energy and the compoundsneeded to build new cells and tissues.


GLUCOSE

‘‘Carbohydrates.’’ Kimball’s Biology Pages.http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Carbohydrates.html (accessed on October 10, 2005).

‘‘Dextrose, Anhydrous.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/D0835.htm(accessed on October 10, 2005).

‘‘Glucose.’’ Department of Chemistry, Imperial College London.http://www.ch.ic.ac.uk/vchemlib/mim/bristol/glucose/glucose_text.htm (accessed on October 10, 2005).

See Also Fructose; Sucrose


GLUCOSE

OTHER NAMES:Glycerin; glycerine;

glycyl alcohol

FORMULA:CH2OHCHOHCH2OH


oxygen

COMPOUND TYPE:Trihydric alcohol

(organic)

STATE:Liquid




SOLUBILITY:Miscible with water

and alcohol; insolublein ether, benzene, and

chloroform

Glycerol

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OVERVIEW

Glycerol (GLIH-ser-ol) is a clear, colorless, odorless, sweet-tasting syrupy liquid. It is a trihydric alcohol, meaning thatits molecules contain three hydroxyl (-OH) groups. Glyceroloccurs naturally in all animal and plant cells. Glycerol wasdiscovered in 1779 by the German chemist Karl WilhelmScheele (1742–1786) and named by the French chemist MichelEugene Chevreul (1786–1889) because of its sweet taste(glycos means ‘‘sweet’’ in Greek). In 1836 the French chemistTheophile-Jules Pelouze (1807–1867) determined the molecu-lar formula for glycerol, and three decades later, in 1872, thecompound was first synthesized (created in a laboratory) bythe French chemist Charles Friedel (1832–1899). About 250million kilograms (500 million pounds) of glycerol are pro-duced in the United States each year, the majority of whichgoes to the production of food and personal care products.

HOW IT IS MADE

The traditional method of making glycerol is by thesaponification of fats. Fats are the esters of glycerol and

H H

OH OH OH

H H H

C CC


one or more alcohols. When a fat is hydrolyzed in the pre-sence of a catalyst, it is converted into the glycerol andalcohols from which it was originally made. This type ofhydrolysis is called saponification because it is the usualmethod by which soaps (the Latin word for ‘‘soap’’ is sapon).Glycerol can be obtained, then, as a byproduct in the manu-facture of soaps.

A number of synthetic methods for making glycerol arealso available. Most of these procedures begin with propylene(propene; CH2=CHCH3) and chlorine and involve a series ofsteps that convert the three-carbon propylene to the three-carbon glycerol. Glycerol can also be obtained by treatingsimple sugars with hydrogen over a nickel catalyst. In theUnited States, about 80 percent of all glycerol producedis obtained by saponification methods, and the remaining20 percent is made by synthetic methods.


The most common use for glycerol in the United States isin food products, where it acts as a sweetener and as athickener in many foods. For example, it is added to icecream to improve texture and to candy products and baked

Glycerol. Red atoms areoxygen; white atoms are




GLYCEROL

goods to increase the sweetness of the product. It is also usedto make the flexible coatings on cheeses, sausages, and othermeat products. About one-quarter of all glycerol made in theUnited States is used in the food products industry.

Nearly the same amount of glycerol is used in the pre-paration of personal care products, such as skin, hair, andsoap products (23 percent) and in oral hygiene products, suchas toothpastes and mouthwashes (17 percent). Some of theproducts that include glycerol are moisturizers, detergents,soaps, hair coloring agents, mascara, nail polish, nail polishremovers, perfumes, body lotions, hair sprays, shavingcreams, lipsticks, cough medicines, shampoos, and hair con-ditioners. Glycerol is also used as a humectant in tobaccos.A humectant is a material that helps a product conservemoisture and prevent it from drying out.

Other uses for glycerol include:

• In the manufacturer of explosives;

• In the production of a variety of plastics and polymers,such as polyether polyols, urethanes, and alkyd resins;

• As a lubricant in pumps, bearings, gaskets, and othermechanical systems;

• In the manufacture of ink rolls, inks, and rubberstamps;

• As an emulsifying agent, a material that helps twoliquids that are not soluble in each other to stay mixed;

• As an antifreeze; and

• In a number of medical applications, such as the treat-ment of glaucoma and stroke.

Interesting Facts

• As winter approaches,many insects begin toproduce glycerol to replacethe water in their bodytissues. Glycerol acts as an

antifreeze to prevent theinsects from freezingduring the coldest part ofthe year.


GLYCEROL

Glycerol poses some safety problems because it is com-bustible and explosive under certain conditions. It presentsno health hazards under normal circumstances of use, how-ever.


‘‘Glycerol.’’ International Chemical Safety Cards.http://www.healthy communications.com/msdsglycerin1.html(accessed on October 10, 2005).

‘‘Glycerol.’’ PDRhealth.http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/gly_0304.shtml (accessed on October 10, 2005).

Legwold, Gary. ‘‘Hydration Breakthrough.’’ Bicycling (July 1994):72 73.

‘‘Material Safety Data Sheet: Glycerine. ’ Department of Chemistry,Iowa State University.http://avogadro.chem.iastate.edu/MSDS/glycerine.htm(accessed on October 10, 2005).

Words to Know






GLYCEROL

OTHER NAMES:n-hexane

FORMULA:C6H14




STATE:Liquid





very soluble in ethylalcohol; soluble in

ether and chloroform

Hexane

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OVERVIEW

Hexane (HEX-ane) is a colorless flammable liquid with afaint petroleum-like odor. Chemically it is classified as asaturated hydrocarbon, which means that its molecules con-tain only carbon and hydrogen atoms joined only by singlebonds. Saturated hydrocarbons are also known as alkanes. Byfar its most important use is as a solvent in a variety ofindustrial operations.

HOW IT IS MADE

Hexane is extracted from petroleum. Petroleum is a com-plex mixture of solid, liquid, and gaseous hydrocarbons thathas virtually no use itself. However, the fractional distilla-tion of petroleum produces hundreds of individual com-pounds, each of which has its own important commercialand industrial applications. Fractional distillation is the pro-cess by which petroleum is heated in tall towers. The compo-nents of petroleum boil off at different temperatures, rise to

CH3

H3CCC

C C

H

H H H H

HH H


different heights in the tower, and are condensed at differentlevels above the base of the tower. As a liquid with a lowboiling point, hexane boils off and rises to upper levels ofthe tower, where it condenses and is removed in a portion ofthe petroleum known as petroleum ether or ligroin. Hexanecan then be separated from other constituents of petroleumether by a second distillation, in which each componentboils off and is condensed at its own distinctive boilingpoint.


By far the most important use of hexane is in solventsused for a variety of purposes, such as the extraction of oilsfrom seeds and vegetables; as a degreaser and cleaning agentfor printing equipment; as a solvent in glues such as rubbercement; as an ingredient in inks and varnishes; in the shoeand leather manufacturing industry; and in the roofingindustry.

Hexane poses both safety and health risks for humansand other animals. The liquid vaporizes easily and the vaporsformed ignite easily and may even explode under the properconditions. The primary health hazard related to hexaneoccurs by breathing in the compound. When inhaled, it cancause numbness in the hands and feet, weakness in the feetand lower legs, paralysis of the arms and legs, muscle wasting,

Hexane. White atoms arehydrogen and black atoms are




HEXANE

damage to nerves, nausea and vomiting, jaundice, skinrashes, irritation of the eyes and throat, blurred vision,mental confusion, and coma. There is no evidence, however,that hexane is carcinogenic.

The health hazards posed by hexane are of concern inonly two circumstances: among workers who handle theliquid on a regular basis; and among people who deliberatelyinhale the compound as part of a solvent for the purpose ofgetting ‘‘high.’’ In both cases, a person is exposed to muchhigher concentrations of hexane that one would encounter incommercial or industrial products. The practice of glue-sniff-ing, which has become popular among some teenagers, canresult in serious health problems, including dizziness,increased heart rate, high blood pressure, disorientation,confusion, and occasionally violent impulses or suicideattempts.

Interesting Facts

• Hexane to which a red orblue dye has been addedis sometimes used to

make thermometers usedfor measuring lowtemperatures.

Words to Know


DISTILLATION A process of separating twoor more substances by boiling the mixtureof which they are composed and conden-

sing the vapors produced at differenttemperatures.

SOLVENT A liquid in which anothersubstance is dissolved, to form asolution.


HEXANE


‘‘Hexane.’’ U.S. Environmental Protection Agency TechnologyTransfer Network, Air Toxics Website.http://www.epa.gov/ttn/atw/hlthef/hexane.html (accessed onOctober 12, 2005).

Menhard, Francha Roffe. The Facts about Inhalants. New York:Benchmark Books, 2004.

‘‘ToxFAQs for n hexane.’’ Agency for Toxic Substances and DiseaseRegistry.http://www.atsdr.cdc.gov/tfacts113.html (accessed on October12, 2005).


HEXANE

OTHER NAMES:Anhydrous

hydrochloric acid

FORMULA:HCl

ELEMENTS:Hydrogen; chlorine


STATE:Gas



BOILING POINT:�85�C (�121�F)

SOLUBILITY:Very soluble in

water; soluble inalcohol and ether

Hydrogen Chloride

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OVERVIEW

Hydrogen chloride (HY-druh-jin KLOR-ide) is a colorlessgas with a strong, suffocating odor. The gas is not flammable,but is corrosive, that is, capable of attacking and reactingwith a large variety of other compounds and elements.Hydrogen chloride is most commonly available as an aqueoussolution known as hydrochloric acid. It is one of the mostimportant industrial chemicals in the world. In 2004, justover 5 million metric tons (5.5 million short tons) of hydro-gen chloride were produced in the United States, making itthe eighteenth most important chemical in the nation forthat year.

Hydrogen chloride has probably been known as far backas the eighth century, when the Arabian chemist Jabir ibnHayyan (c. 721–c. 815; also known by his Latinized name ofGeber) described the production of a gas from common tablesalt (sodium chloride; NaCl) and sulfuric acid (H2SO4). Thecompound was mentioned in the writings of a number ofalchemists during the Middle Ages and was probably first

H

Cl


produced in a reasonably pure form by the German chemistJohann Rudolf Glauber (1604–1670) in about 1625. The firstmodern chemist to prepare hydrogen chloride and describeits properties was the English chemist Joseph Priestley(1733–1804) in 1772. Forty years later, in 1818, the Englishchemistry and physicist Humphry Davy (1778–1829) showedthat the compound consisted of hydrogen and chlorine, giv-ing it the correct formula of HCl.

Commercial production of hydrogen chloride had itsbeginning in Great Britain in 1823. The method of produc-tion most popular there and, later, throughout Europe wasone originally developed by the French chemist NicholasLeblanc (1742–1806) in 1783. Leblanc had invented the pro-cess as a method for producing sodium hydroxide and sodiumcarbonate, two very important industrial chemicals. Hydro-gen chloride was produced as a byproduct of the Leblancprocess, a byproduct for which there was at first no use.The gas was simply allowed to escape into the air. The suffo-cating and hazardous release of hydrogen chloride promptedgovernments to pass legislation requiring some other meansof disposal for the gas. In England, that law was called theAlkali Act and was adopted by the parliament in 1863. Unableto release hydrogen chloride into the air, manufacturersbegan dissolving it in water and producing hydrochloric acid.Before long, a number of important commercial and indus-trial uses for the acid itself were discovered. The ‘‘useless’’byproduct of the Leblanc process soon became as importantas the primary products of the process, sodium hydroxideand sodium carbonate.

Hydrogen chloride. Whiteatom is hydrogen and green

atom is chlorine. P U B L I S H E R S



HYDROGEN CHLORIDE

HOW IT IS MADE

Hydrogen chloride is still sometimes made today by thetraditional process of reacting sodium chloride (NaCl) with asulfate, such as sulfuric acid or iron(II) sulfate (FeSO4). How-ever, more than 90 percent of the hydrogen chloride pro-duced throughout the world today comes as the byproduct ofthe chlorination of organic compounds. Chlorination is theprocess by which chlorine gas reacts with an organic com-pound, usually replacing some of the hydrogen present in thecompound. Since a large number of important chlorinatedorganic compounds are produced each year, large amounts ofhydrogen chloride gas are produced as a byproduct. That gasis simply removed from the reaction and stored in cylindersfor future use. Other methods of producing hydrogen chlor-ide include the direct synthesis of hydrogen gas and chlorinegas (producing a very pure product) and the reaction ofsodium chloride, sulfur dioxide, oxygen, and water with eachother at high temperatures (the Hargreaves process).


Hydrogen chloride and hydrochloric acid have some usesin common, and some that are different from each other. Inboth dry and liquid form, the largest single use of hydrogenchloride is in the synthesis of organic and inorganic chlor-ides. A large number of compounds important in commerceand industry contain chlorine, including most pesticides,many pharmaceuticals, and a number of polymeric products.

Interesting Facts

• Hydrogen chloride wasstudied by the famousalchemist Basil Valentine(c. 1394–?), who gave itthe name spiritus salis

(‘‘the spirit of salt’’) bywhich it was known tomost alchemists.

• Hydrochloric acid has tra-ditionally been known asmuriatic acid, a name thatis still sometimes used byworkers in fields in whichit is used.


HYDROGEN CHLORIDE

Hydrochloric acid is also used widely in the processing ofmetallic ores and the pickling of metals. Pickling is theprocess by which a metal is cleaned, usually with an acid,to remove rust and other impurities that have collected onthe metal. Some additional uses of hydrogen chloride andhydrochloric acid include the following:

• In the brining of foods and other materials. Brining isthe process by which a material is soaked in a saltsolution, usually in order to preserve the material;

• In the treatment of swimming pool water;

• As a catalyst in industrial chemical reactions;

• In the manufacture of semiconductors and other elec-tronic components;

• To maintain the proper acidity in oil wells (to keep oilflowing smoothly);

• For the etching of concrete surfaces;

• In the production of aluminum, titanium, and a numberof other important metals.

Both hydrogen chloride and hydrochloric acid pose serioushealth risks to humans and other animals. The gas is anirritant to the eyes and respiratory system, causing coughing,choking, and tearing, as well as more serious damage to tis-sues. Hydrochloric acid can burn the skin and mucous mem-branes. Exposure of only five parts per million of the gas canproduce noticeable symptoms of distress, and exposure ofmore than 2,000 parts per million can be fatal. If hydrochloric

Words to Know


ANHYDROUS Without water or moisture.

AQUEOUS A solution is one that consists ofsome material dissolved in water.

CATALYST A material that increases therate of a chemical reaction without under-going any change in its own chemicalstructure.



HYDROGEN CHLORIDE

acid gets into the eyes, blindness may result. Since hydrochlo-ric acid is present in many household products, users shouldexercise great care when working with such materials.


‘‘Hydrochloric Acid.’’ National Safety Council.http://www.nsc.org/library/chemical/Hydrochl.htm (accessedon October 12, 2005).

‘‘Hydrogen Chloride.’’ Agency for Toxic Substances and DiseaseRegistry.http://www.atsdr.cdc.gov/tfacts173.pdf (accessed on October12, 2005).

‘‘Hydrogen Chloride.’’http://www.ucc.ie/ucc/depts/chem/dolchem/html/comp/hcl.html(accessed on October 12, 2005).

‘‘Hydrogen Chloride, HCl.’’ Defense Service Center.http://www.c f c.com/gaslink/pure/hydrogen chloride.htm(accessed on October 12, 2005).

See Also Sodium Chloride


HYDROGEN CHLORIDE

OTHER NAMES:Hydrogen dioxide;

hydroperoxide;peroxide

FORMULA:H2O2

ELEMENTS:Hydrogen; oxygen

COMPOUND TYPE:Oxide (inorganic)

STATE:Liquid





soluble in ether

Hydrogen Peroxide

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OVERVIEW

Hydrogen peroxide (HY-druh-jin per-OK-side) is a clear,colorless, somewhat unstable liquid with a bitter taste.

When absolutely pure, the compound is quite stable. Evensmall amounts of impurities (such as iron or copper),

however, act as catalysts that increase its tendency todecompose, sometimes violently, into water and nascentoxygen (O). To prevent decomposition, small amounts of

inhibitors, such as acetanilide or sodium stannate areadded to pure hydrogen peroxide and hydrogen peroxide

solutions.

Hydrogen peroxide was discovered in 1818 by French

chemist Louis Jacques Thenard (1777–1857). It was first usedcommercially in the 1800s, primarily to bleach hats. Today,industrial processes make about 500 million kilograms

(1 billion pounds) of hydrogen peroxide annually for use in awide variety of applications ranging from whitening of teeth

to propelling rockets.

H O O H


HOW IT IS MADE

Hydrogen peroxide occurs in very small amounts in nat-ure. It is formed when atmospheric oxygen reacts with waterto form H2O2. Hydrogen peroxide is also present in plant andanimal cells as the byproduct of metabolic reactions thatoccur in those cells.

The large amounts of hydrogen peroxide used in industryare prepared in a complex series of reactions that beginswith any one of a family of compounds known as the alkylanthrahydroquinones, such as ethyl anthrahydroquinone.The anthrahydroquinones are three-ring compounds thatcan be converted back and forth between two or more similarstructures. During the conversion from one structure toanother, hydrogen peroxide is produced as a byproduct. Theanthraquinone is continuously regenerated during the pro-duction of hydrogen peroxide, making the process very effi-cient.

Other methods for the preparation of hydrogen peroxideare also available. For example, the electrolysis of sulfuricacid results in the formation of a related compound, peroxy-sulfuric acid (H2SO5), which then reacts with water to formhydrogen peroxide. A third method of preparation involvesthe heating of isopropyl alcohol [2-propanol; (CH3)2CHOH] athigh temperature and pressure, resulting in the formation ofhydrogen peroxide as one product of the reaction.

Hydrogen peroxide. Red atomsare oxygen and white atoms are




HYDROGEN PEROXIDE


Most of hydrogen peroxide’s applications depend on thefact that it tends to break down, releasing a single atom ofnascent oxygen (O):

H2O2 ! H2O + (O)

The term nascent oxygen refers to a single atom ofoxygen, a structure that is chemically very active. Nascentoxygen tends to be a very strong oxidizing agent. For exam-ple, the use of hydrogen peroxide with which most people areprobably familiar is as an antiseptic, a substance used to killgerms. Hydrogen peroxide achieves this result because thenascent oxygen it releases destroys bacteria, fungi, and othermicroorganisms that cause disease.

The most important industrial application of hydrogenperoxide—its use in the pulp and paper industry—alsodepends on its oxidizing properties. In this case, it is usedto bleach the materials of which paper is made, convertingcolored compounds to colorless compounds. About 55 percentof all hydrogen peroxide made in the United States is usedfor this purpose. Another nine percent is used in the bleach-ing of other materials, such as textiles, furs, feathers, andhair. Another important application of hydrogen peroxide isin water and sewage treatment plants, where its antibacterialaction destroys disease-causing organisms in the water. Someadditional uses of hydrogen peroxide include:

• In bakeries to condition dough and make it easier towork with;

• For cleaning metals;

• As a rocket propellant;

Interesting Facts

• Hydrogen peroxide is soldin concentrations rangingfrom 3 percent (for homeuse) to 90 percent (forindustrial applications).

• Scientists have discoveredhydrogen peroxide in theatmosphere of Mars.


HYDROGEN PEROXIDE

• In the preparation of other organic and inorganic com-pounds;

• As a neutralizing agent in the production of wines; and

• As a disinfectant in the treatment of seeds for agricul-tural purposes.

The hydrogen peroxide solutions with which people comeinto contact at home pose little or no health hazard becausethe concentration of the compound is very low, usually about3 percent. Prolonged use of hydrogen peroxide may causeburns on the skin, however, and the more concentrated solu-tions used in industry present more serious hazards. They canbe toxic if ingested and are explosive if not stored properly.


‘‘Hydrogen Peroxide (>60% Solution in Water).’’ InternationalLabour Organization.http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc01/icsc0164.htm(accessed on October 12, 2005).

‘‘Introduction to Hydrogen Peroxide.’’ U.S. Peroxide.http://www.h2o2.com/intro/overview.html(accessed on October 12, 2005).

‘‘A Prescription for Death?’’ CBSNews.comhttp://www.cbsnews.com/stories/2005/01/12/60II/main666489.shtml (accessed on October 12, 2005).

Words to Know

CATALYST A material that increases therate of a chemical reaction without under-going any change in its own chemicalstructure.

INHIBITOR A substance added to anothersubstance to prevent or slow down anunwanted reaction.

METABOLISM A process that includes all ofthe chemical reactions that occur in cells


OXIDATION A chemical reaction in whichoxygen reacts with some other substanceor, alternatively, in which some substancesloses electrons to another substance, theoxidizing agent.


HYDROGEN PEROXIDE

OTHER NAMES:Ferrous oxide; iron

monoxide

FORMULA:FeO

ELEMENTS:Iron, oxygen

COMPOUND TYPE:Metal oxide

STATE:Solid





all ordinary organicsolvents; soluble in

acids

Iron(II) Oxide

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OVERVIEW

Iron(II) oxide (EYE-urn two OK-side) is a black, densepowder that occurs in nature as the mineral wustite. It reactsreadily with oxygen in the air to form iron(III) oxide andwith carbon dioxide to form iron(II) carbonate (FeCO3).

HOW IT IS MADE

Iron(II) oxide occurs in nature as the result of the incom-plete oxidation of iron metal. It can be prepared syntheticallyby heating iron(II) oxalate (FeC2O4), although the product ofthis reaction is contaminated with another oxide of iron,triiron tetroxide (Fe3O4).


Iron(II) oxide has three primary uses. First, it has longbeen used as a dye or pigment in pottery, glazes, and glasses,especially in the green, heat-absorbing glass used in build-ings, automobiles, and other applications. The compound is

Fe = O


also used as a raw material in the production of steel. Finally,iron(II) oxide is used as a catalyst in a number of industrialand chemical operations.

Inhalation of iron(II) oxide fumes or dust is considered ahazard and can cause throat and nasal irritation. High levelsof exposure may lead to a condition known as metal fumefever, a workplace exposure illness that causes flu-like symp-toms. Continued exposure at high levels can have more ser-ious effects, including a disease known as siderosis, an inflam-mation of the lungs that is accompanied by pneumonia-likesymptoms.

Iron(II) oxide. Red atom isoxygen and orange atom isiron. Gray stick is a double


G R O U P

Interesting Facts

• Both iron(II) oxide and itscousin, iron(III) oxide areabundant in rocks on thesurface of Mars. The for-mer accounts for the dark,nearly jet black, color

of some rocks, whilethe latter is responsiblefor the predominantred color of the planet’ssurface.


IRON(II) OXIDE


Cornell, Rochelle M., and Udo Schwertmann. The Iron Oxides;

Structure, Properties, Reactions, and Uses. Second edition.New York: Wiley VCH, 2003.

‘‘Ferrous Oxide.’’ International Programme for Chemical Safety.http://www.inchem.org/documents/icsc/icsc/eics0793.htm(accessed on October 12, 2005).

‘‘Material Safety Data Sheet.’’ ESPI Metals.http://www.espimetals.com/msds’s/ironoxidefeo.pdf(accessed on October 12, 2005).

See Also Iron(III) Oxide

Words to Know

OXIDATION A chemical reaction in whichoxygen reacts with some other substanceor, alternatively, in which some substances

loses electrons to another substance, theoxidizing agent.


IRON(II) OXIDE

OTHER NAMES:Ferric oxide; red iron

oxide; red irontrioxide

FORMULA:Fe2O3

ELEMENTS:Iron; oxygen


STATE:Solid





all conventionalorganic solvents;

soluble in acids

Iron(III) Oxide

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OVERVIEW

Iron(III) oxide (EYE-urn three OK-side) is a dense, red-dish-brown, crystalline compound that usually occurs as

lumps or a powder. It occurs in nature as the mineral hema-tite and is a component of the rust that forms on objects

made out of iron that are exposed to the air. Rust itself isactually a complex mixture of iron oxides and hydroxides,

including Fe2O3, FeO, Fe3O4 and FeO(OH). Hematite mayrange in color from black and silver gray to reddish brownand red depending on the type and amount of impurities

present with iron(III) oxide. Iron(III) is also ferromagnetic.Ferromagnetism refers to the ability of a substance to

become highly magnetic and then retain its magnetism.

HOW IT IS MADE

Hematitite forms naturally when iron-containing rocksand minerals react with oxygen in the air to form iron(III)

oxide. The oxide can be made synthetically by a variety of

O OFe Fe

O


procedures. In the most popular method, iron(II) sulfate is

reacted with sodium hydroxide (NaOH) to produce iron(II)hydroxide [Fe(OH)2]. The iron(II) hydroxide is then allowed

to react with oxygen in the air, forming iron(III) oxide.The compound can also be produced by heating iron(II) sul-

fate, hydrated iron(II) oxide (FeO(OH)), or iron(III) oxalate[Fe2(C2O3)3].


Iron(III) oxides has been associated with the manufac-ture of iron and steel for much of human history. The IronAge, which began in Egypt around 4000 BCE was the periodin human history when iron was used for tools and weap-ons. The general approach to refining iron metal from ironores, such as hematite, was to heat the ore in the presenceof carbon. Carbon removes oxygen from the ore, leavingthe free metal behind. By the first century BCE in China,the first known blast furnaces were in use. In a blastfurnace, iron(III) oxide is reduced with carbon by using ablast of air and heat. The oxygen from the air reacts withcarbon to give carbon monoxide, which then reacts withiron(III) oxide to produce liquid iron metal and carbondioxide.

In the eighteenth century, the blast furnace processwas further developed so that iron could be made commer-cially. This process can be traced to the region around

Iron(III) oxide. Red atomsare oxygen and orange atoms

are iron. P U B L I S H E R S



IRON(III) OXIDE

Coalbrookdale in Shropshire, England, around the year 1773and is said to have been a factor in initiating the IndustrialRevolution. The blast furnace method is still one of the

primary methods by which iron metal is refined fromiron ores.

Iron(III) oxide is also one of the oldest known pigmentsand has been used for that purpose in every major civiliza-

tion. Some of the best known pigments made from iron(III)oxide have been Indian red, terra Pozzuoli, and Venetian redand have been used to color ceramic glazes and paints.

Depending on the exact formulation used, iron(III) oxideproduces colors ranging from yellow to orange to red. For

example, the hydrated oxide produces a pigment rangingfrom yellow to brown. Iron(III) oxide pigments have been

used as pigment for rubber, paper, linoleum, glass, and manytypes of paints, including specialty paints used on metalwork

and ship hulls.

Some of the other commercial and industrial applicationsof iron(III) oxide include:

Interesting Facts

• The name hematite isderived from the Greekword for blood.

• When hematite is madeinto an ornament, it issometimes called blackdiamond.

• NASA’s Mars rover Oppor-tunity found small parti-cles thought to be mostlyhematite on the planet’ssurface. Scientists thinkthey formed billions of

years ago when Mars hadwater on its surface.

• Paleolithic humans inSwaziland, who lived morethan 40,000 years ago,mined hematite in theoldest known mine in thearchaeological recordcalled the Lion Cave. It isthought that they minedthe hematite to producethe red pigment known asochre.


IRON(III) OXIDE

• As a catalyst for many industrial and chemical operations;

• As a component of thermite, a mixture of iron(III) oxideand aluminum powder which, when ignited, producesvery hot temperatures. Thermite bombs are used inwelding;

• In computer hard disks, audio cassette tapes, videocassette tapes, and computer floppy disks for magneticstorage of data;

• As an abrasive and polish for use with brass, steel,gems, and other hard objects;


• As a feed additive for domestic animals to ensureproper levels of iron in their systems; and

• In the manufacture of magnets and magnetic materials.

Exposure to iron(III) oxide dust can cause irritation ofthe eyes and throat. Long-term exposure to dust particles cancause chronic inflammation of the lungs.


Crutchfield, Charlie. ‘‘Re: What Do the Different Colors of RustMean, Chemically.’’ MadSci Network.http://www.madsci.org/posts/archives/2002 03/1015309769.Ch.r.html (accessed on October 12, 2005).

‘‘Ferric Oxide.’’ International Labour Organization.http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc15/icsc1577.htm (accessed on October12, 2005).

Words to Know




IRON(III) OXIDE

Ricketts, John A. ‘‘How a Blast Furnace Works.’’ American Iron andSteel Institute.http://www.steel.org/AM/Template.cfm?Section=Home&template=/CM/HTMLDisplay.cfm&ContentID=5433(accessed on October 12, 2005).

See Also Carbon Monoxide; Iron(II) Oxide


IRON(III) OXIDE

OTHER NAMES:Isopentyl acetate;

isoamyl ethanoate;amylacetic ester

FORMULA:CH3COOCH2CH2CH

(CH3)2


oxygen


STATE:Liquid





water; soluble in mostorganic solvents

Isoamyl Acetate

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OVERVIEW

Isoamyl acetate (EYE-so-A-mil AS-uh-tate) is a clear, color-less liquid with a pleasant fruity odor and taste reminiscentof pears or bananas. When prepared for industrial or com-mercial use, it is often known as pear oil or banana oil.

HOW IT IS MADE

Isoamyl acetate is made commercially by reacting aceticacid (CH3COOH) with amyl alcohol (C4H9CH2OH) to produceamyl acetate, of which there are eight isomers. The isomersare then separated from each other by fractional distillationto obtain the one desired form, isoamyl acetate.


Isoamyl acetate is a very popular additive for imparting apleasant odor or taste to commercial products. Since 1976,the U.S. Patent Office has issued 1,174 patents for inventions

H3C

CH3

CH3

C

C C C

H H H

H

H

O

O


that contain the compound. Some of the products to which itis added include:

• Foods and drinks, such as gum, candy, mineral water,beer, and syrups used to make soft drinks;

• Personal care products, such as perfume, nail polish,leather polish, and shoe polish;

• Furniture polish, varnishes, and lacquers; and

• Dry cleaning preparation.

In addition to these applications, isoamyl acetate has anumber of other uses, including

• The fermentation of grain to produce whiskey;

• To mask unpleasant odors;

• In the manufacture of a number of industrial and house-hold products, including bath sponges, artificial

Isoamyl acetate. Red atomsare oxygen; white atomsare hydrogen; and black

atoms are carbon. Gray sticksindicate double bonds.

P U B L I S H E R S R E S O U R C E

G R O U P


ISOAMYL ACETATE

leather, artificial silk, rayon, artificial pearls, artificialglass, bronzing fluid, metallic paint, fluorescent lamps,and photographic film;

• In the dyeing and finishing of textiles; and

• As a solvent for old oil paints.

Isoamyl acetate is flammable and is rated as a severe firehazard. It is also explosive. The chemical should not be usedaround open flames or sparks. People should not smokearound isoamyl acetate.

Isoamyl acetate is also an irritant to the skin, eyes, andrespiratory and digestive systems. If swallowed it may causesore throat, nausea, and abdominal pain. People who work

Interesting Facts

• When a bee stings, itleaves behind traces ofisoamyl acetate at the siteof the sting. The isoamylacetate then attracts otherbees to the same site,accounting for thetendency for an individualto receive multiple stingsat the same point on his orher body.

• One species of Japanesehoneybees defends itselffrom attacks by hornetpredators by surroundingthe hornet with a ball thatconsists primarily ofisoamyl acetate. The ballbecomes so hot that thehornet dies.

Words to Know


ISOMER One of two or more forms ofa chemical compound with the samemolecular formula, but differentstructural formulas and differentchemical and physical properties.


ISOAMYL ACETATE

with the pure compound are at greater risk for harm fromthe compound than are those who use it in commercialproducts.


‘‘Isoamyl Acetate.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/icsc/icsc/eics0356.htm(accessed on October 12, 2005).

‘‘Occupational Safety and Health Guideline for Isoamyl Acetate.’’Occupational Safety & Health Administration.http://www.osha.gov/SLTC/healthguidelines/isoamylacetate/recognition.html (accessed on October 12, 2005).

Shukla, Nutan. ‘‘Honeybees Come to Know of Queen’s Deaththrough Smell.’’ The Tribune Spectrum.

http://www.tribuneindia.com/2003/20030601/spectrum/nature.htm (accessed on October 12, 2005).

‘‘Unusual Thermal Defence by a Honeybee against Mass Attack byHornets.’’ Nature (September 28, 1995): 334 336.


ISOAMYL ACETATE

OTHER NAMES:2-methyl-

1,3-butadiene

FORMULA:CH2=CH(CH3)CH=CH2


COMPOUND TYPE:Alkadiene;

unsaturatedhydrocarbon

(organic)

STATE:Liquid





miscible with ethylalcohol, acetone,

ether, and benzene

Isoprene

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OVERVIEW

Isoprene (EYE-so-preen) is a clear, colorless, volatileliquid that is both very flammable and quite explosive. It isclassified as a diene compound because its molecules containtwo (‘‘di-’’) double bonds (‘‘-ene’’). It is also a member of theterpene family. The terpenes are a large family of organiccompounds that contain two or more isoprene units. Anexample of a terpene is vitamin A, whose molecular formulais C20H30O. Vitamin A contains four isoprene units. Theterpenes occur abundantly in nature in both plants andanimals.

Some common terpenes include geraniol, found in gera-niums; limonene, oil of orange; a-pinene, or oil of turpentine;a-farnesene, oil of cintronella; zingiberene, oil of ginger;farnesol, found in lily of the valley; b-selinene, oil of celery;and caryophyllene, oil of cloves. Isoprene is also produced inanimal bodies and is said to be the most common hydrocar-bon present in the human body. By one estimate, a 70-kilo-gram (150-pound) person produces about 17 milligrams of

CH H

H

C CC C

HH

HH

H


isoprene per day. Probably the best-known source of isopreneis natural rubber, which is a polymer consisting of longchains of isoprene units joined to each other.

HOW IT IS MADE

A number of methods are available for preparing iso-prene from petroleum. Perhaps the most common process isthe cracking of hydrocarbons present in the naphtha portionof refined petroleum. Cracking is the process by which largehydrocarbons are broken down into smaller hydrocarbonseither with heat or over a catalyst, or by some combinationof heat and catalyst. The naphtha portion of petroleum con-sists of hydrocarbons with boiling points between about50�C and 200�C (120�F and 400�F). Other methods for the

Isoprene. Black atoms arecarbon; white atoms are

hydrogen. Gray sticks showdouble bonds; white sticks

show single bonds. P U B L I S H E R S



ISOPRENE

preparation of isoprene include the dehydrogenation(removal of hydrogen) of isopentene (CH3CH(CH3)CH=CH2),the pyrolysis (decomposition by high heat) of methylpentene(CH2=C(CH3)CH2CH2CH3), or the dehydration (removal ofwater) of methylbutenol (CH3C(CH3)(OH)CH2CH3).


Natural rubber has been known to humans for hundredsof years. Archaeologists have found that the Indians ofSouth and Central America were making rubber productsas early as the eleventh century. Until the end of the nine-teenth century, natural supplies of rubber obtained fromthe rubber tree, Hevea brasiliensis, were sufficient to meetconsumer demand for the product. However, with the devel-opment of modern technology—especially the invention ofthe automobile—natural supplies of the product proved to

Interesting Facts

• Isoprene and otherterpenes are now knownto undergo reactions thatcontribute to the develop-ment of pollutants,such as ozone and oxidesof nitrogen in theatmosphere.

• Isoprene is a key inter-mediary in the synthesisof cholesterol in thehuman body.

• The production of isopreneby plants seems to beassociated with theprocess of photosynthesisand is affected bytemperature, sunlight,

other gases, and otherfactors.

• The polymer of isoprene iscalled polyisoprene. Itexists in two forms, cis- andtrans-polyisoprene. The twoforms are called geometric

isomers. They have thesame kind and numberof atoms, but the atomsare arranged differentlyin the two forms. Naturalrubber consists of trans-polyisoprene, whileanother product foundin rubber plants, guttapercha, is made ofcis-polyisoprene.


ISOPRENE

be insufficient to meet growing demand. Chemical researchersbegan to look for ways of producing synthetic forms ofrubber.

One approach was to attempt making synthetic rubberwith exactly the same chemical composition as that of nat-ural rubber, that is, a polymer of trans-polyisoprene. As earlyas the 1880s, British chemist Sir William Augustus Tilden(1842–1926) was successful in achieving this objective. Tildenfound that he could make isoprene by heating turpentine(C10H16 ). The isoprene then polymerized easily when exposedto light. After more than twenty years of research, however,Tilden decided that synthetic trans-polyisoprene could neverbe made economically, and he encouraged his friends toforget about the process.

Over the years, chemists did find ways of making othertypes of synthetic rubber, and some never abandoned theeffort to make synthetic trans-polyisoprene. The criticalbreakthrough needed in this research occurred in about1953 when Swiss chemist Karl Ziegler (1898–1973) and Ita-lian chemist Giulio Natta (1903–1979) each found a way ofpolymerizing isoprene in such a way that its geometricstructure matched that of natural rubber exactly. A yearlater, chemists at two of the largest rubber companies inthe world, B. F. Goodrich and Firestone, announced that theyhad developed methods for making synthetic trans-polyiso-prene using essentially the methods developed earlier byZiegler and Natta.

In the early twenty-first century, more than 95 percentof the isoprene produced is used to make trans-polyisoprenesynthetic rubber. The remaining 5 percent is used to makeother types of synthetic rubber and other kinds of polymers.A small amount of the compound is used as a chemicalintermediary, a substance from which other organic chemi-cals is made.

Isoprene is a dangerous fire hazard. It also poses a risk tohuman health and that of other animals. It is an irritant toskin, eyes, and the respiratory system. Upon exposure, itproduces symptoms such as redness, watering, and itchingof the eyes and itching, reddening, and blistering of the skin.If inhaled, it can irritate the lungs and respiratory system.Isoprene is a known carcinogen.


ISOPRENE


‘‘Hazardous Substance Fact Sheet: Isoprene.’’ New Jersey Department of Health and Senior Services.http://www.state.nj.us/health/eoh/rtkweb/1069.pdf (accessedon December 29, 2005).

‘‘Isoprene.’’ Shell Chemicals.http://www.shellchemicals.com/isoprene/1,1098,1116,00.html(accessed on December 29, 2005).

‘‘Material Safety Data Sheet: Isoprene MSDS.’’ ScienceLab.com.http://www.sciencelab.com/xMSDS Isoprene 9924409(accessed on December 29, 2005).

‘‘United States Synthetic Rubber Program, 1939 1945.’’ NationalHistoric Chemical Landmarks, American Chemical Society.http://acswebcontent.acs.org/landmarks/landmarks/rbb/rbb_begin.html (accessed on December 29, 2005).

Weissermel, Klaus, and Hans Jurgen Arpe. Industrial Organic

Chemistry. Weinheim, Germany: Wiley VCH, 2003, 117 122.

See Also Poly(Styrene-Butadiene-Styrene)

Words to Know



PHOTOSYNTHESIS The process by whichgreen plants and some other organismsuse the energy in sunlight to convert

carbon dioxide and water intocarbohydrates and oxygen.


VOLATILE Able to turn to vapor easily at arelatively low temperature.


ISOPRENE

OTHER NAMES:2-propanol;

isopropanol; rubbingalcohol

FORMULA:CH3CHOHCH3


oxygen


STATE:Liquid




SOLUBILITY:Miscible with water

and most commonorganic solvents

Isopropyl Alcohol

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OVERVIEW

Isopropyl alcohol (EYE-so-PRO-pil AL-ko-hol) is a colorlessflammable liquid with a sweet odor. In 2004, about 600million kilograms (about 1.3 billion pounds) of isopropylalcohol were produced in the United States, with about halfof that used as an industrial solvent and about a third used inthe preparation of other chemical compounds. It is perhapsbest known to many people as rubbing alcohol, usually a 70percent solution of isopropyl alcohol in water. The compoundis commonly used to clean a person’s skin before an injectionis given. It kills bacteria on the skin and prevents infection.

HOW IT IS MADE

The most popular industrial method for preparing iso-propyl alcohol was invented in 1920 by researchers at theStandard Oil Company (now Exxon). In that process, propene(propylene; CH2CH=CH2) is treated with hydrolyzed with sul-furic acid as a catalyst.

CCH3

CH3

HHO



Isopropyl alcohol dissolves many other organic com-pounds easily, so it finds wide use as a solvent for gums;essential and other kinds of oils; alkaloids; certain types ofplastics; derivatives of cellulose; paints, varnishes, shellacs,and other types of coatings; and quick-drying inks. Essentialoils are oils extracted from plants that have therapeuticvalue. Alkaloids are organic bases that contain the elementnitrogen.

The synthesis of many important organic compoundsbegins with isopropyl alcohol as a raw material. Among thesecompounds are acetone, glycerol, and isopropyl acetate, itselfwidely used as a solvent for organic substances. Among theother uses to which isopropyl alcohol is put are:

Isopropyl alcohol. Red atom isoxygen; white atoms are




ISOPROPYL ALCOHOL

• In household and personal care products, such as per-fumes, hair dye rinses, nail polishes, shampoos, andafter-shave lotions;

• In cleaning products, such as disinfectant soaps andhand and body lotions;

• In antifreezes and as a deicing agent;

• As a coolant in the manufacture of beers; and

• As a preservative for biological specimens.


‘‘Isopropanol.’’ Spectrum Laboratories.http://www.speclab.com/compound/c67630.htm (accessed onOctober 12, 2005).

‘‘Isopropyl Alcohol.’’ New Jersey Department of Health and SeniorServices.http://www.state.nj.us/health/eoh/rtkweb/1076.pdf (accessedon October 12, 2005).

‘‘2 Propanol.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/sids/sids/67630.pdf(accessed on October 12, 2005).

See Also Propylene

Words to Know


MISCIBLE Able to be mixed; especiallyapplies to the mixing of one liquidwith another.


ISOPROPYL ALCOHOL

OTHER NAMES:2-hydroxypropanoicacid; a-hydroxypro-

panoic acid; milk acid

FORMULA:CH3CHOHCOOH


oxygen


(organic)

STATE:Liquid




decomposes uponheating

SOLUBILITY:Very soluble in waterand ethanol; slightly

soluble in ether

Lactic Acid

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OVERVIEW

Lactic acid (LAK-tik AS-id) is a colorless, odorless, syrupyliquid that occurs in two isomeric forms, D-lactic acid andL-lactic acid. Isomers are two or more forms of a chemicalcompound with the same molecular formula, but differentstructural formulas and different chemical and physicalproperties. The D form is produced during metabolic reac-tions that take place in muscle tissue, while the L form isproduced by yeast cells. The synthetic production of lacticacid results in a product consisting of equal amounts of the Dand L forms, a mixture known as a racemic mixture.

Lactic acid was first discovered in 1780 by the Swedishchemist Karl Wilhelm Scheele (1742–1786), who called his dis-covery ‘‘acid of milk.’’ The two isomeric forms of the acid werefirst identified in 1863 by the German chemist Johannes Wisli-cenus (1835–1902), and the compound was first produced com-mercially in 1881 by American chemist Charles E. Avery. Averypatented his invention in 1885 and constructed a factory forthe production of lactic acid in Littleton, Massachusetts.

CH3C

OH

HOH

HC


About 30 million kilograms (72 million pounds) of lacticacid are produced annually in the United States. The mostcommon method of production is the fermentation of glucoseby yeast.

HOW IT IS MADE

In muscle cells, lactic acid is the product of anaerobicrespiration, the process by which glucose is oxidized in theabsence of oxygen to produce energy required by cells.Although some lactic acid is always produced in muscle cellsin very low concentrations, it tends to accumulate duringexercise, when cells do not receive adequate amounts ofoxygen to metabolize oxygen by normal pathways. Lacticacid produced during exercise remains in the body for onlyshort periods of time, sometimes in less than thirty minutes.It is metabolized in the muscle cells where it was produced,resulting in the production of energy, carbon dioxide, water,and other products.

Lactic acid. Red atoms areoxygen; white atoms

are hydrogen; and black atomsare carbon. Gray sticks indicate




LACTIC ACID

Lactic acid is also produced by yeast during the processof fermentation. Fermentation is the process by which yeastcells convert glucose to an alcohol and carbon dioxide. Yeastcells use almost precisely the same enzyme in fermentationthat muscle cells use in anaerobic respiration. The musclecell enzyme and the yeast enzyme differ only in the orienta-tion of one group of atoms, resulting in the production of theD isomer in one case and the L isomer in the other.

A synthetic process for the production of lactic acidwas first introduced in 1963. That process begins with theaddition of hydrogen cyanide (HCN) to acetaldehyde (ethanal;CH3CHO), resulting in the formation of lactonitrile (CH3

CH2OCN). The lactonitrile is then hydrolyzed, using a strongacid, such as sulfuric acid, as a catalyst, to make lactic acid.


The primary use for lactic acid in the United States is asa food additive, where it acts as an acidulant and a flavoradditive. An acidulant is a compound that provides an acidicenvironment for foods, as is the case with yogurt, butter-milk, sauerkraut, green olives, pickles, and other acidicfoods. As a flavor additive, it adds a tart or tangy flavor tofoods and beverages, as well as acting as a preservative tokeep them from spoiling. Lactic acid also has a number ofimportant industrial uses, the most important of which is the

Interesting Facts

• For the better part of acentury, athletes and phy-siologists have consideredlactic acid a primary causeof fatigue during high-intensity exercise. How-ever, scientists havelearned that lactic acidactually helps to preventmuscle fatigue. Musclesoreness once thought to

be caused by lactic acid is,instead, more likely to be aresult of damaged musclecells caused by excess use.

• Lactic acid present on theskin attracts mosquitoes.

• Lactic acid in the bodyexists in its ionic form,known as lactate.


LACTIC ACID

production of other organic chemicals, especially ethyl lac-tate, acrylic acid, propylene glycol, and the polymer known aspolyactide. Polyactide is used in the manufacture of plasticfilm, fiber, packaging material, and filling materials. Othercommercial and industrial applications of lactic acid include:

• As a mordant in dyeing;

• As a solvent for dyes that are not soluble in water;

• For the treatment of animal hides in the preparation ofleather products;

• As a catalyst in the production of certain types ofplastics; and

• As an additive in electroplating baths.

Lactic acid in normal concentrations poses no safety orhealth hazards to humans or other animals. One health con-sequence related to lactic acid, however, is a condition knownas gout, a type of arthritis that causes severe pain in thejoints. Gout is caused by an accumulation of uric acid in the

Words to Know

CATALYST A material that increases the rateof a chemical reaction without under-going any change in its own chemicalstructure.

ELECTROPLATING Adding a layer of nickel,silver, or gold, on another type of metalusing an electric current.

FERMENTATION The process by which yeastconvert glucose to an alcohol and carbondioxide.


ISOMER One of two or more forms of achemical compound with the same mole-cular formula, but different structural

formulas and different chemical andphysical properties.

METABOLISM A process that includes all ofthe chemical reactions that occur in cellsby which fats, carbohydrates, and othercompounds are broken down to produceenergy and the compounds needed tobuild new cells and tissues.




LACTIC ACID

blood. Since lactic acid blocks the elimination of uric acidfrom the body, individuals with excess lactic acid buildup,usually caused by high alcohol consumption, may develop anexcess of uric acid crystals in the blood and joints, leading togout.


‘‘Cell Respiration.’’ SparkNotes.http://www.sparknotes.com/testprep/books/sat2/biology/chapter6section1.rhtml (accessed on October 14, 2005).

Drake, Geoff. ‘‘The Lactate Shuttle Contrary to What You’veHeard, Lactic Acid Is Your Friend.’’ Bicycling (August 1992):36.

Friel, Joel. ‘‘All Athletes: Lactic Acid’s Bad Rap.’’ Ultrafit’s e TipsFor Endurance Athletes. October 2004, Vol. 7, No. 10.http://www.ultrafit.com/newsletter/october04.html#Joe(accessed on October 14, 2005).

‘‘Lactic Acid.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/l0522.htm(accessed on October 14, 2005).

Rogers, Palmer, Jiann Shin Chen, and Mary Jo Zidwick. Organic

Acid and Solvent Production, Part I: Acetic, Lactic, Gluconic,

Succinic, and Polyhydroxyalkanoic Acids. Section 2: LacticAcid. Available online athttp://141.150.157.117:8080/prokPUB/chaphtm/306/04_00.htm (accessed on October 14, 2005).


LACTIC ACID

OTHER NAMES:D-lactose; milk sugar;

many others

FORMULA:C12H22O11


oxygen

COMPOUND TYPE:Disaccharide;carbohydrate

(organic)

STATE:Solid




decomposes


slightly solublein ethyl alcohol;

insoluble in organicsolvents

Lactose

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OVERVIEW

Lactose (LAK-tose) is a white, odorless, sweet-tastingsolid commonly known as milk sugar because it occurs inthe milk of many animals, primarily the mammals. The lac-tose content of milk ranges from about 2 to 8 percent in cowsand 5 to 8 percent in human milk. Lactose occurs in twoisomeric forms, a-lactose and b-lactose, with the latter some-what sweeter than the former. The alpha form tends to occuras the monohydrate, C12H22O11�H2O.

HOW IT IS MADE

Lactose is synthesized in the mammary (milk-producing)glands of mammals. The milk of such animals contains anenzyme called lactose synthetase, which acts on the com-pound uridine diphosphate D-galactose to produce lactose.The compound is obtained commercially from whey, a bypro-duct of the cheese-making process. The solids in whey con-tain about 70 percent lactose by weight. These solids are

HO

HO

HO

H

H

H

H

H

HH

HO

OH

H

H

H

H

OH

OH

OHH

H

C

CO

O

CC

C

C

C

C

C

O

C

C C


filtered to remove the proteins they contain. After removalof minerals in the whey, the resulting solution consists ofabout 50 to 65 percent by weight, which is allowed to crystal-lize out of the resulting solutions. The lactose produced bythis process is a racemic mixture of the D and L isomers. Toobtain the alpha isomer, the lactose is dissolved with waterand treated with activated carbon to remove any color. Whenthe water evaporates from the solution, a-lactose monohy-drate remains. The product is most commonly made availablein this form. To obtain the beta isomer, a-lactose is heatedwith water in the presence of a base, which converts thealpha isomer to its beta form.


Both forms of lactose are used in the preparation of babyfoods and food for infants and for convalescents. It is alsoused in the dairy industry to feed foals that have been

Lactose. Red atoms areoxygen; white atoms are




LACTOSE

orphaned. Lactose is also used as a food additive, primarily asa humectant and to increase the sweet flavor of a food. Ahumectant helps foods retain their moisture. It is used inproducts such as ice creams, baked goods, confectionaryitems, whipped toppings, and breakfast foods. Lactose mayalso be added to a number of foods with limited naturalsweetness, such as margarine, butter, frozen vegetables,and processed meats. It is also used as a filler for manypharmaceutical products. A filler acts bulk to the productwithout significantly changing its nutritional or medicalproperties.

Many people are lactose intolerant. Lactose intoleranceis a condition that develops when a person lacks enough (orany) of the enzyme lactase that is responsible for digestionof lactose in the body. People who are lactose intolerant andconsume lactose experience a range of unpleasant symp-toms, including fluid retention, gas, cramps, and diarrhea.By some estimates, up to 75 percent of the world’s popula-tion may experience lactose intolerance to a greater or lesserdegree.

One method for dealing with lactose intolerance is for aperson to avoid consumption of any food or food product thatcontains lactose. The option has been made somewhat easierby the introduction of lactose-free products by a number offood companies. Another method to avoid the problems asso-ciated with lactose intolerance is to use a dietary supplementthat contains lactase, restoring to the body the enzyme thatit lacks naturally.

Interesting Facts

• Only one group of mam-mals does not producelactose in their milk, thePinnipedia, a group thatincludes seals, sea lions,and walruses.

• Alpha lactose is found incow’s milk and beta lactosein human milk. Duringpasteurization of cow’smilk, the alpha isomer isconverted into the betaisomer.


LACTOSE


‘‘Lactose.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/l1044.htm(accessed on October 14, 2005).

‘‘Lactose Intolerance.’’ Medline Plus.http://www.nlm.nih.gov/medlineplus/lactoseintolerance.html(accessed on October 14, 2005).

‘‘Lactose Intolerance.’’ National Digestive Diseases InformationClearinghouse.http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/ (accessed on October 14, 2005).

See Also Sucrose

Words to Know


MAMMALS A group of warm-blood animalswhose females produce milk for their

young. This group includes humans, cows,bears, and dogs, among others.

RACEMIC MIXTURE A mixture of equalamounts of two opposite isomers (the‘‘right-handed,’’ or ‘‘D’’ form and the‘‘left-handed,’’ or ‘‘L’’ form).


LACTOSE

OTHER NAMES:Aspartame

FORMULA:C14H18N2O5


nitrogen, oxygen


STATE:Solid




SOLUBILITY:Slightly soluble inwater; insoluble in

alcohol, benzene,ether, and most other

organic solvents

L-Aspartyl-L-Phenyl-alanine Methyl Ester

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OVERVIEW

L-aspartyl-L-phenylalanine methyl ester (ell-ass-par-TEELell-fee-no-AL-uh-neen METH-el ESS-ter) is an artificial sweet-ener more widely known as aspartame. It is sold under anumber of brand names, including NutraSweet�, Equal�,Spoonful�, Benevia�, Indulge�, NatraTaste�, and Equal-Measure�. Unlike sugar, which is a carbohydrate, aspartameis a dipeptide, a compound made of two amino acids joined toeach other. It is 180 to 200 times as sweet as sucrose (tablesugar), but provides no calories to a person’s diet. It is asatisfactory substitute for sugar, therefore, for people whomust or wish to reduce their caloric intake.

Aspartame was discovered accidentally in 1965 by JamesM. Schlatter, an employee of the G. D. Searle pharmaceuticalcompany. Schlatter was searching for a chemical compoundthat could be used to treat ulcers. L-aspartyl-L-phenylalaninemethyl ester was one of the compounds he made during hisinvestigations. He accidentally got some of the compound onhis fingers, a fact that he did not notice until later in the day.

C C

O

C C

C CC

C C C O

OH

C C

HC N N

H

H

H

H

H

H

H

H

H

H

H

H

H

O O

H3C


Then, when he licked his fingers to pick up a piece of paper,he noticed the intensely sweet taste of the compound. Toconfirm his suspicions about the compound, he added someof it to his coffee—a practice that violates all laboratorysafety rules!—and found that it was more than satisfactoryas a substitute for sugar. Searle began the testing and appli-cation procedure needed to gain approval from the U.S. Foodand Drug Administration, a long and drawn-out procedurethat ended only in 1981, 25 years after its discovery.

L Aspartyl L phenylalanine

methyl ester. Red atomsare oxygen; white atoms arehydrogen; black atoms are

carbon; and blue atomsare nitrogen. Gray sticks show



L ASPARTYL L PHENYLALANINE METHYL ESTER


HOW IT IS MADE

Aspartame is made by a relatively simple procedure inwhich two amino acids, aspartic acid and phenylalanine,are reacted with each other to form a two-amino-acid pro-duct, called a dipeptide. The carboxylic acid group in thedipeptide is then reacted with methanol (methyl alcohol;CH3OH) to obtain the methyl ester of the compound. Oneproblem that makes the preparation somewhat more diffi-cult is that both aspartic acid and phenylalanine havestereoisomers. The term stereoisomer refers to two formsof a compound that contain the same kind and number ofatoms, but differ in the orientation in space (‘‘stereo-’’) ofsome of the atoms. Because of these stereoisomers, fourdifferent kinds of aspartame are formed during the pre-paration described above — D & D; L & L; D & L; L & D (thelatter two are different from each other). Only one is thedesired product, the one that contains only ‘‘L’’ stereo-isomers.


Aspartame’s primary commercial use is as an artificialsweetener. Some of the products that contain aspartame arebreath mints, carbonated soft drinks, cereals, chewing gum,sugar-free gelatin, hard candies, ice cream toppings, sugar-free ice cream, ready-to-drink iced tea, instant cocoa mix, jamsand jellies, juice drinks, nutritional bars, protein nutritionaldrinks, diet puddings, sugar-free chocolate syrup, sugar-freecookies, table top sweeteners, and fat- and sugar-free yogurt.The compound is also used to a lesser extent as a flavorenhancer, a substance that intensifies an already-existingflavor.

Interesting Facts

• The Aspartame InformationCenter claims that thecompound is now used inmore than 6,000 commer-

cial products and con-sumed by more than 100million people worldwide.



The use of aspartame as a food additive in the UnitedStates has a long and complex history. As required for FDAapproval, Searle conducted a number of studies to show thataspartame is safe for human consumption. Based on theresults of those studies, the FDA first granted approval forthe use of aspartame in certain types of foods on July 26,1974. Less than a month later, two concerned citizens, JamesTurner and Dr. John Olney, filed a petition objecting to theFDA’s decision, citing possible errors in Searle’s testingprocedures on aspartame. After continued studies extend-ing over a seven-year period, the FDA once again approvedaspartame for use in dry foods. A year later, the agencyextended its approval for aspartame to dry beverage mixesand add-in sweeteners and, in 1983, to beverages and otherfoods.

The campaign against aspartame has not lessened overthe years. Today, a number of individuals and groups main-tain organizations and websites whose purpose it is to haveaspartame banned as a food additive. Continued studies bythe manufacturer and independent researchers seem to con-firm the safety of aspartame, but have found that two groupsof people do face some level of risk by ingesting the com-pound. The first group consists of people who seem to havesome natural allergy to the compound and experience symp-toms such as anxiety attacks, breathing difficulties, dizzi-ness, unusual fatigue, headaches, heart palpitations, skinrashes, muscle spasms, nausea, numbness, respiratory aller-gies, weight gain, and memory loss. Individuals who experi-ence such problems are encouraged to avoid eating or drink-ing products that contain aspartame.

A second group for whom aspartame is a far more ser-ious problem consists of individuals with phenylketonuria.Phenylketonuria is a genetic disorder in which a person’sbody is unable to metabolize the amino acid phenylalanine,a component of aspartame. If phenylalanine is ingested bysomeone with phenylketonuria, the amino acid builds up inthe body and causes a number of organic problems, includ-ing mental retardation, damage to the organs, and musculardisorders. Any product that contains aspartame is nowrequired by law to have a warning label aimed at phenylk-etonuriacs so that they will not accidentally ingest thecompound.




‘‘Aspartame.’’ Chemical Land 21.http://www.chemicalland21.com/lifescience/foco/ASPARTAME.htm (accessed on September 21, 2005).

‘‘Aspartame Information Center.’’http://www.aspartame.org/ (accessed on September 21, 2005).

‘‘Low Calorie Sweeteners: Aspartame.’’ Calorie Control Council.http://www.caloriecontrol.org/aspartame.html (accessed onSeptember 21, 2005).

Metcalfe, Ed., et al. ‘‘Sweet Talking.’’ The Ecologist (June 2000): 16.

Words to Know

DIPEPTIDE A compound made of two aminoacids joined to each other.

METHYL ESTER A compound formed whenmethyl alcohol (methanol) reacts with anorganic acid.

PHENYLKETONURIA A genetic disorderin which a person’s body is unable tometabolize the amino acid phenylalanine.

STEREOISOMER One of a pair of molecules,both of which have the same kinds andnumber of atoms, but which differ in howsome of the atoms are oriented in relationto each other.



OTHER NAMES:5-amino-2,3-dihydro-

1,4-phthalazinedione;3-aminophthalhydra-

zide

FORMULA:C8H7N3O2


nitrogen, oxygen

COMPOUND TYPE:Heterocyclic ring

(organic)

STATE:Solid


MELTING POINT:319�C to 320�C (606�F

to 608�F)


decomposes


water; soluble inalcohol

Luminol

KE

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OVERVIEW

Luminol (LOO-min-ol) is a substance that glows when itcome in contact with blood. It was discovered in the latenineteenth century, but chemists found little use for thecompound for half a century. Then, in 1928, the Germanchemist H. O. Albrecht found that the addition of hydrogenperoxide to luminol produces a bluish-green glow, an exam-ple of the phenomenon known as chemiluminescence. Che-miluminescence is the process by which light is emitted asthe result of a chemical reaction. Albrecht found that thereaction between hydrogen peroxide and luminol required acatalyst, a small amount of a metal such as copper or iron.

The most important application for luminol was discov-ered in 1937 by the German forensic scientist Walter Specht(1907–1977), at the University Institute for Legal Medicineand Scientific Criminalistics in Jena, Germany. Spechtfound that blood itself could act as the catalyst needed toproduce chemiluminescence with luminol. He simplysprayed a mixture of luminol and hydrogen peroxide on a

C C

O

O

CC

C

C

C

C

N

N

N

H

H

HH


drop of blood, and the blood emitted a bluish-green glow.Specht later determined the explanation for this reaction.Blood contains a protein called hemoglobin that carriesoxygen from the lungs to cells. Hemoglobin is a complexmolecule with a single iron atom at its center. The smallamount of iron in hemoglobin is sufficient to initiate thechemiluminescent reaction between luminol and hydrogenperoxide.

Luminol. Red atomsare oxygen; white atoms are

hydrogen; black atomsare carbon; and blue atoms arenitrogen. Gray sticks indicate




LUMINOL

HOW IT IS MADE

Luminol is prepared commercially by treating 3-nitrophthalicacid (C8H5NO6) with hydrazine (NH2NH2), resulting in theformation of nitrophthalhydrazide. Nitrophthalhydrazideis then treated with sodium bisulfite (NaHSO3) to obtainluminol.


The most common application of luminol is to find tracesof blood at crime scenes. When a violent crime is committed,a certain amount of blood is often spilled on the floor, walls,furniture, and other objects at the crime scene. The perpe-trator of the crime may attempt to clean up after the crime,but it is virtually impossible to remove all traces of blood.Forensic scientists who investigate a crime scene oftenassume that blood is present, even if it is not obvious. Theycheck for the blood by spraying a mixture of luminol andhydrogen peroxide around the crime scene. If blood is pre-sent, it glows with a bluish-green color. The distribution ofthe blood can provide information as to where the crime wascommitted, whether the injured or murdered person wasmoved, and, if so, in what direction. Investigators typicallytake photographs of the illuminated crime scene for study ata later date.

False positive results are possible with a luminol test. Afalse positive test is a test in which the results seem toindicate the presence of blood even if it is not actually there.Some metals, plants, paints, cleaning materials, and other

Interesting Facts

• Luminol can be used todetect bloodstains that aremany years old.

• One disadvantage ofusing luminol in testingfor blood is that it

destroys the samplebeing investigated,making further tests onthe same sampleimpossible.


LUMINOL

substances may act as catalysts for the reaction betweenluminol and hydrogen peroxide and give a false positive test.For this reason, positive tests obtained by the luminolreagent are always subjected to further tests to confirm theresults.

Luminol does have applications beyond criminal investi-gations. It is the active ingredient in glow sticks, the plasticsticks that glow green when broken. Chemists use the com-pound in chromatography, a process by which the compo-nents of a mixture are separated from each other, as well asin studies of DNA patterns and other biochemical tests.


Genge, Ngaire E. The Forensic Casebook: The Science of Crime

Scene Investigation. New York: Ballantine, 2002.

‘‘Material Safety Data Sheet for Luminol = 3 Aminophthalhydrazide, 98%.’’ Department of Chemistry, Iowa State University.http://avogadro.chem.iastate.edu/MSDS/luminol.htm(accessed on October 14, 2005).

‘‘Nitric Oxide/NOS Detection (incl. Kits/Sets).’’ Axxora.http://www.axxora.com/nitric_oxide nos_detection_(incl._kitssets) ALX 610 002/opfa.1.1.ALX 610 002.169.4.1.html(accessed on October 14, 2005).

‘‘Technical Note: HemaglowTM.’’ Lightning Powder Company.http://www.redwop.com/technotes.asp?ID=118 (accessed onOctober 14, 2005).

Words to Know

CATALYST A material that increases therate of a chemical reaction without

undergoing any change in its ownchemical structure.


LUMINOL

OTHER NAMES:Magnesium

dichloride

FORMULA:MgCl2

ELEMENTS:Magnesium, chlorine

COMPOUND TYPE:Inorganic salt; binary

salt

STATE:Solid


MELTING POINT:714�C (1,320�F)

BOILING POINT:1,412�C (2,574�F)


moderately soluble inethyl alcohol

Magnesium Chloride

KE

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OVERVIEW

Magnesium chloride (mag-NEE-zee-um KLOR-ide) is awhite crystalline solid that is strongly deliquescent. Itabsorbs moisture from the air to become the hydrated form,magnesium chloride hexahydrate (MgCl2�6H2O). A deliques-cent substance is one that takes on moisture from the air,often to the extent of dissolving in its own water of hydra-tion. Magnesium chloride is an important industrial chemi-cal, used in the production of magnesium, textile and papermanufacture, and cements; in refrigeration and fireproofing;and as a deicing agent.

HOW IT IS MADE

Magnesium chloride is extracted from seawater or brine,of which it is a component, and from minerals, such as carnal-lite (KCl�MgCl2�H2O) and bischofite (MgCl2�6H2O). The usualprocedure is to treat seawater, brine, or the mineral with lime(CaO), calcined dolomite (CaO�MgO), or caustic soda (sodium

Mg++Cl– Cl–


hydroxide; NaOH) to make magnesium hydroxide [Mg(OH)2],which is then treated with hydrochloric acid (HCl) to recovermagnesium chloride, which is usually obtained as the crystal-line hexahydrate. The pure compound is also produced byheating the double salt, magnesium ammonium chloride(MgCl2�NH4Cl�6H2O), which first loses its water of hydrationto form the anhydous double salt (MgCl2�NH4Cl). With furtherheating, the ammonium chloride sublimes, leaving behindpure anhydrous magnesium chloride.


The largest single use of magnesium chloride is in theproduction of magnesium metal. The metal is obtainedthrough the electrolysis of molten magnesium chloride in aprocess developed by the American chemist and inventorHerbert Henry Dow (1866–1930) in 1916. The Dow process isstill the primary method used for the production of magne-sium metal. Other commercial and industrial uses of magne-sium chloride include:

• In the manufacture of disinfectants;

• In the fireproofing of steel beams, wooden panels, andother materials;

• As a component of fire extinguishers;

• In the manufacture of so-called Sorel cement, a mixtureof magnesium chloride and magnesium oxide, alsoknown as oxychloride cement;

• As a binder to control dust on dirt roads;

• As a deicing compound;

Magnesium chloride

hexahydrate. Green atoms arechlorine; and turquoise atom is

magnesium. P U B L I S H E R S



MAGNESIUM CHLORIDE

• To remove suspended particles in water and sewagetreatment plants;

• For the treatment of cotton and wool fabrics;

• In the processing of sugar beets;

• To keep drilling tools cool; and

• In the manufacture of paper and ceramic materials.

Magnesium chloride is a skin, nose, and eye irritant,although that hazard is usually a matter of concern only tothose who work with the pure compound. It is also toxic byingestion. Swallowing the compound can produce nausea,vomiting, and diarrhea. Inhalation of magnesium chloridefumes can irritate the lungs and respiratory tract, produ-cing a condition known as metal fume fever that resemblesthe flu.

Interesting Facts

• Tofu is traditionallyprepared by treating soy

milk with magnesiumchloride or calcium sulfate.

Words to Know

ANHYDROUS A compound that lacks anywater of hydration.

DELIQUESCENT Describing a substance thattakes on moisture from the air, often tothe extent of dissolving in its own waterof hydration.

HYDRATE A chemical compound formedwhen one or more molecules of water is

added physically to the molecule ofsome other substance.

SUBLIMATION The process by which asolid changes directly into a gaswithout first melting.



MAGNESIUM CHLORIDE


‘‘Magnesium Chloride.’’ ChemicalLand21.com.http://www.chemicalland21.com/arokorhi/industrialchem/inorganic/MAGNESIUM%20CHLORIDE.htm (accessed onOctober 14, 2005).

‘‘Magnesium Chloride.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/m0156.htm(accessed on October 14, 2005).

See Also Magnesium Hydroxide


MAGNESIUM CHLORIDE

OTHER NAMES:Magnesium hydrate;

milk of magnesia;magnesia magma

FORMULA:Mg(OH)2

ELEMENTS:Magnesium,

hydrogen, oxygen


STATE:Solid


MELTING POINT:Decomposes at

350�C (660�F)


SOLUBILITY:Virtually insoluble in

water and alcohol,soluble in dilute acids

and solutions ofammonium salts

Magnesium Hydroxide

KE

YF

AC

TS

OVERVIEW

Magnesium hydroxide (mag-NEE-zee-um hye-DROK-side)is a white powder with no odor, found in nature as themineral brucite. Perhaps the best known form of the com-pound is a milky liquid known as milk of magnesia, a productused to treat upset stomach and constipation. Milk of mag-nesia was invented in 1817 by the Irish pharmacist Sir JamesMurray (1788–1871). Murray built a plant to produce a mix-ture of magnesium hydroxide in water that he sold for thetreatment of a variety of ailments, including heartburn,stomach acidity, bladder and bowel problems, and ‘‘femaleproblems.’’ He said that the liquid mixture was much moreeffective than powdery magnesium hydroxide which hadpreviously been used for the same purposes.

In 1880, New York chemist Charles Henry Phillips(1820–1882) invented the name ‘‘milk of magnesia’’ andopened his own factory for producing the product. The namePhillips Milk of Magnesia is one of the oldest and best knownover-the-counter medicines ever made in the United States.

H HO- O-

Mg2+


HOW IT IS MADE

Magnesium hydroxide is prepared by reacting a magne-sium salt, such as magnesium chloride (MgCl2), with sodiumhydroxide (NaOH). In a similar procedure, seawater (whichcontains small amounts of magnesium chloride) is treatedwith lime (calcium oxide; CaO). The water, lime, and magne-sium chloride react to produce magnesium hydroxide, whichsettles out of solution as a precipitate.


The best known use for magnesium hydroxide is as anantacid in the form of milk of magnesia. Since magnesiumhydroxide is a base, it reacts with excess stomach acid, whichreduces heartburn and the discomfort of upset stomach.

Magnesium hydroxide. Redatoms are oxygen; white atoms

are hydrogen; and turquoiseatom is magnesium.


Interesting Facts

• The element magnesiumis named after a regionin Greece called Magnesiain ancient times. Todaythe same region is calledManisa. Compounds of

magnesium, includingmagnesium hydroxide,were abundant in theregion and were given thename of magnesia lithos,or ‘‘stones of Magnesia.’’


MAGNESIUM HYDROXIDE

Milk of magnesia also acts as a laxative because it increasesthe flow of water into the intestines, stimulating a bowelmovement. Milk of magnesia consists of an 8 percent suspen-sion of solid magnesium hydroxide in water. Other chemi-cals, such as calcium carbonate and aluminum hydroxide, aresometimes added to the mixture to increase its effectiveness.

Magnesium hydroxide also has a number of importantindustrial uses, such as:

• A clarifier (a substance that removes impurities) in therefining of sugar;

• An additive in the treatment of wastewater to neutra-lize acids present in the wastes;

• A flame retardant coating on fabrics and other materi-als used by consumers and industries;

• An additive to fuel oils;

• An additive in toothpastes; and

• A drying agent in some food products.


Dean, Carolyn. The Miracle of Magnesium. New York: BallantineBooks, 2003.

‘‘Magnesium Hydroxide.’’ Chemical Land 21.http://www.chemicalland21.com/arokorhi/industrialchem/inorganic/MAGNESIUM%20HYDROXIDE.htm (accessed onSeptember 14, 2005).

See Also Magnesium Oxide

Words to Know

ANTACID A medicine used for the treatmentof upset stomach, acid indigestion, andrelated symptoms.

CLARIFIER A substance that removes impu-rities from another substance.

PRECIPITATE A solid material that settlesout of a solution, often as the result ofa chemical reaction.

SUSPENSION A mixture of two substancesthat do not dissolve in each other.


MAGNESIUM HYDROXIDE

OTHER NAMES:Magnesia;

calcined magnesia;magnesia ulba

FORMULA:MgO

ELEMENTS:Magnesium, oxygen


(inorganic)

STATE:Solid



BOILING POINT:3,600�C (6,500�F)


water; soluble in mostacids; insoluble in

alcohol

Magnesium Oxide

KE

YF

AC

TS

OVERVIEW

Magnesium oxide (mag-NEE-see-um OK-side) is availablecommercially in several forms, depending on the way it isprepared and the use for which it is intended. Most forms canbe classified as either ‘‘light’’ or ‘‘heavy’’ depending on particlesize, purity, and method of production. It occurs in nature inthe form of the mineral periclase. In its purest form, magne-sium oxide is a colorless or white crystalline material or veryfine powder, with no odor and a bitter taste.

HOW IT IS MADE

A number of methods are available for the preparation ofmagnesium oxide. Most methods begin with either magnesiumhydroxide [Mg(OH)2] or magnesium carbonate (MgCO3), eitherof which is heated under controlled conditions to produce thedesired product. The primary methods of preparation are:

• Dead-burning, in which the hydroxide or carbonate isheated to temperatures ranging from 1,500�C to

OMg


2,000�C (3,000� to 4,000�F), so-called because the finalproduct is largely chemically unreactive;

• Hard-burning (also known as caustic-burned), in whichthe hydroxide or carbonate is heated to somewhat lowertemperatures, between 1,000�C and 1,500�C (2,000�Fand 3,000�F), allowing the compound to retain some ofits chemical reactivity;

• Light-burning, in which the temperature is keptbetween 700�C and 1,000�C (1,500�F and 2,000�F),resulting in a product with even more reactivity; and

• Fusion, in which the hydroxide or carbonate is heatedto temperatures in excess of 2,650�C (4,800�F), produ-cing a very dense, inert product.

An especially pure form of magnesium oxide can be madeby taking the product from any of the above reactions andmaking a slurry with water. A slurry is a mud-like mixture ofa solid and liquid that normally do not form a solution.Various chemicals can then be added to the magnesium oxideslurry to remove any contaminants, and the purified slurry isallowed to dry.


Each form of magnesium oxide has its specialized uses:

• Dead-burned: As refractory brick for cement kilns, fur-naces, crucibles, and equipment used in the manufac-ture of steel;

• Hard-burned: In the production of fertilizers and animalfeed, in the extraction of uranium oxide from uranium

Magnesium oxide. Black atomis magnesium; red atom is

oxygen; the stick represents adouble bond. P U B L I S H E R S



MAGNESIUM OXIDE

ore, as a catalyst, in the manufacture of ceramics, forthe tanning of leather, in the synthesis of magnesiumcompounds, and (its most important single use) in pol-lution control devices that remove sulfur dioxide fromplant exhaust gases;

• Light-burned: In the processing of paper and pulp; as afiller in products made of rubber; and as an ingredientin a host of household and personal care products suchas dusting powders, cosmetics, and pharmaceuticals.Some of the best-known pharmaceuticals containingmagnesium oxide are antacids used to treat heartburn,upset stomach, or acid indigestion and laxatives for thetreatment of constipation or in preparation for surgery.

• Fusion: As refractory linings for electric arc furnacesand in insulating materials used in many householdelectrical products.

Interesting Facts

• Magnesium oxide is some-times used as a gemstonecalled periclase. It is foundin a wide range of colorsfrom colorless or white to

yellow to brown. Its use asa gemstone is somewhatlimited, however, because itis not very hard.

Words to Know

CATALYST A material that increases the rateof a chemical reaction without under-going any change in its own chemicalstructure.

REFRACTORY MATERIAL A material with ahigh melting point, resistant to melting,

often used to line the interior ofindustrial furnaces.



MAGNESIUM OXIDE

Contact with magnesium oxide dust or fumes may irri-tate the skin, eyes, or respiratory system. Symptoms of expo-sure may include fatigue and lethargy. The greatest concernfor such health hazards rests with people who come intocontact with the pure product in their line of work.


‘‘Everything You Wanted to Know about Magnesium Oxide.’’ Martin Marietta Magnesia Specialties.http://www.magspecialties.com/students.htm (accessed onOctober 14, 2005).

‘‘Magnesia Magnesium Oxide (MgO).’’ Azom.com.http://www.azom.com/details.asp?ArticleID=54 (accessed onOctober 14, 2005).

See Also Magnesium Hydroxide


MAGNESIUM OXIDE


FORMULA:Mg3Si4O10(OH)2

ELEMENTS:Magnesium, silicon,

oxygen, hydrogen

COMPOUND TYPE:Hydrated salt

(inorganic)

STATE:Solid



begins to lose waterof hydration above

900�C (1600�F)



most organicsolvents

Magnesium SilicateHydroxide

KE

YF

AC

TS

OVERVIEW

Magnesium silicate hydroxide (mag-NEE-zee-um SILL-uh-kate hye-DROK-side) is also known as hydrated magnesiumsilicate, hydrous magnesium silicate, magnesium silicatehydrous, talc, talcum, and soapstone. It belongs to a largefamily of magnesium silicates that occur in nature. Magne-sium silicates contain at least one magnesium ion and one ormore silicate (SiO3) ions, and often contain one or moremolecules of water of hydration. Other members of thefamily include magnesium metasilicate (MgSiO3), magne-sium orthosilicate (Mg2SiO4), magnesium trisilicate(Mg2Si3O8), and magnesium trisilicate pentahydrate(Mg2Si3O8�5H2O).

The naturally-occurring form of magnesium silicatehydroxide is called talc, a soft mineral that feels waxy andsoapy to the touch. This characteristic has led to anothername for the mineral: soapstone. Talc’s chemical formuladiffers somewhat from that of magnesium silicate hydroxide:Mg3Si4O10(OH)2.

OO

O

SiMg2+

2–


Talc is one of the softest minerals known. It has a numer-ical rank of 1 on the Mohs scale of minerals. The Mohs scaleranks minerals from the softest (1 = talc) to the hardest(10 = diamond). Talc is so soft that it can be scratched withthe fingernail. The mineral has a pearly luster and may comein a variety of colors, ranging from white gray, or silver toblack, brown, pink, or green. Color variations depend onimpurities in the mineral.

Magnesium silicate hydroxide normally occurs as a finewhite powder with no odor, insoluble in most solvents, non-combustible, resistant to heat, and with a tendency to absorbmoisture from the air.

HOW IT IS MADE

The magnesium silicates are obtained from naturalsources, such as talc (magnesium silicate hydroxide), ensta-tite (magnesium metasilicate), forsterite (magnesium ortho-silicate), meerschaum (magnesium trisilicate), or serpentine(Mg3Si2O7). In all cases, extraction of the desired compound

Magnesium silicate. Redatoms are oxygen; turquoise

atom is magnesium; and orangeatom is silicon. Gray stickindicates a double bond.



MAGNESIUM SILICATE HYDROXIDE

involves a number of steps in which the mineral is separatedfrom waste products, crushed, purified, and processed into itsdesired form (powder or crystal, for example).


The form of magnesium silicate hydroxide with whichmost people are familiar is talc, the main ingredient intalcum powder. Talcum powder is used directly as a skintreatment, especially for babies, primarily as a moistureabsorbent and for soothing the skin. It is also used in anumber of cosmetic products, including blushes, eye sha-dows, make-up foundations, and face powders. Talc is alsoused widely as an additive to give products a smoother tex-ture. Some products in which it is found include paints,rubber products, roofing materials, ceramics and insecti-cides. Other applications of talc include:

• As a food additive to prevent foods from clumping andsticking together;

• In the polishing of rice;

• In the production of olive oil to improve the product’sclarity;

• For countertops in chemical laboratories;

• As a lubricant between sheeted products, such as parti-cleboard, to prevent individual sheets from sticking toeach other;

• As a filler in a number of products, including soap,putty, plaster, oilcloth, and rubber products; and

• As a non-caking agent in animal feeds and fertilizers.

Interesting Facts

• The magnesium silicatescontain three of the eightmost abundant elementsin Earth’s crust: oxygen(the most abundant

element), silicon (thesecond most abundantelement), and magnesium(the eighth most abundantelement).



Magnesium silicate hydroxide and other forms of mag-nesium silicates have a number of industrial applications,including:

• In the manufacture of glass and ceramic materials;

• As an insulating material for electrical devices;

• As a refractory material in industrial furnaces;

• In clean-up operations following oil spills; and

• As an odor absorbent.

Exposure to talc dust may cause irritation of the skin,respiratory system, and, especially, the eyes. Harmful effectsmay include skin rash, eye damage, and coughing and wheez-ing. These symptoms generally occur only as the result oflong-term and consistent exposure to dust. There is no evi-dence that talc is carcinogenic unless contaminated withother minerals, such as asbestos and/or silica. The amountof talc and other magnesium silicates to which the averageperson is exposed is probably too low to produce any detect-able health effects.


‘‘Chemical Summary: Talc.’’ CHEC’s HealtheHouse.http://www.checnet.org/healthehouse/chemicals/chemicalsdetail.asp?Main_ID=2 (accessed on October 26, 2005).

‘‘Magnesium Silicates.’’ In Pradyot Patnaik. Handbook of Inorganic

Chemicals. New York: McGraw Hil, 2003, 534 535.

Words to Know

ION An atom or a group of atoms with eithera positive or negative charge, because ithas either lost or gained an electron.

MOHS SCALE A numerical scale used tocompare the hardness of a material. Talchas a Mohs value of 1; diamond has a valueof 10.

REFRACTORY MATERIAL A material witha high melting point, resistant tomelting, often used to line the interiorof industrial furnaces.




‘‘Talc.’’ New Jersey Department of Health and Senior Services.http://www.state.nj.us/health/eoh/rtkweb/1773.pdf (accessedon October 26, 2005).

‘‘Talc Mineral Data.’’ Mineral of the Month Club.http://webmineral.com/data/Talc.shtml (accessed on October26, 2005).



OTHER NAMES:None

FORMULA:MgSO4

ELEMENTS:Magnesium, sulfur,

oxygen


STATE:Solid


MELTING POINT:1,127�C (2,061�F);

decomposes



ethyl alcohol, andglycerol; slightly

soluble in ether

Magnesium Sulfate

KE

YF

AC

TS

OVERVIEW

Magnesium sulfate (mag-NEE-zee-um SUL-fate) occurs asthe anhydrous salt and in a number of hydrated forms, includ-ing MgSO4�H2O, MgSO4�4H2O, MgSO4�5H2O, MgSO4�6H2O, andMgSO4�7H2O. The heptahydrate (MgSO4�7H2O) is commonlyknown as Epsom salts. All of the hydrates occur in nature asthe minerals, respectively, kieserite, starkeyite, pentahydrite,hexahydrite, and epsomite. Magnesium sulfate in all forms isa colorless or white crystalline or powdery material with noodor but a bitter taste. The hydrates all lose their water ofhydration when heated. For example, the heptahydrate losesone molecule of water spontaneously at room temperature,four molecules of water when heated above 70�C (160�F), sixmolecules of water at 150�C (300�F), and all seven molecules ofwater above 200�C (400�F).

Magnesium sulfate heptahydrate has been known andused since the late seventeenth century. The term Epsom

salts was introduced in 1695 by the English naturalistNehemiah Grew (1628–1711), who named the compound after

S

O

O O–

O–

Mg++


the spring waters near Epsom, England, from which it wasoften extracted. Grew received a royal patent for the collec-tion, purification, and sale of the compound.

Although Epsom salts were not given their name untilthe late seventeenth century, their use as a therapy for manydisorders was known at least two centuries earlier. Peopletraveled to the Epsom area, as well as to other locationswhere the compound occurred in spring waters, just to drinkthe waters. Among its other benefits, Epsom salts wasregarded as a purgative, a substance that helps empty thebowels (intestines).

HOW IT IS MADE

All forms of magnesium sulfate can be obtained fromnatural sources in a very high degree of purity, which istheir primary source for commercial and industrial applica-tions. For example, simply evaporating the water fromsprings like those around Epsom results in crystalline mag-nesium heptahydrate of sufficient purity for many uses.Water taken from salt lakes may also contain magnesiumsulfate in sufficient concentration to allow its extraction by

Magnesium sulfate

heptahydrate. Red atomsare oxygen; turquoise atom

is magnesium; and yellow atomis sulfur. Gray sticks indicate




MAGNESIUM SULFATE

a process of dilution and evaporation. Anhydrous magnesiumsulfate is obtained from kieserite by dissolving the mineralin water at 90�C (200�F), allowing the solution to cool, andthen removing the crystals that form by filtration or centri-fuging.


Epsom salts, the heptahydrate of magnesium sulfate, haslong been used for its medicinal benefits. When put intobathwater, it helps reduce inflammation and swelling, andrelaxes muscles. People still visit hot springs and other typesof medicinal waters where magnesium sulfate is one of thedissolved substances that contributes to one’s well-being. Thecompound is also sold over the counter for use at home forsimilar purposes.

The various forms of magnesium sulfate also have anumber of important commercial and industrial uses, includ-ing:

• As an animal feed, to ensure that animals receive themagnesium they require in their diets;

• In fertilizers, with the function of treating soil formagnesium deficiencies;

• In the textile industry, where it is used for weightingand sizing silk, as a mordant, for treating finishedcotton fabric, and in fireproofing fabrics;

• In the production of ceramics;

• In the preparation of a specialized form of cementknown as oxysulfate cement;

• In electroplating processes;

Interesting Facts

• Up to 2 percent of sea saltmay consist of magnesiumsulfate.


MAGNESIUM SULFATE

• As a catalyst for some chemical and industrial opera-tions; and

• For the synthesis of a number of magnesium com-pounds, such as magnesium stearate, used in specia-lized types of soaps.

In dry form, magnesium sulfate can cause irritation ofthe skin, eyes, and respiratory system, producing symptomssuch as sneezing and dryness of the mucous membranes (thesoft tissues lining the breathing and digestive passages);pain, redness and tearing of the eyes; and nausea, vomiting,abdominal cramps, and diarrhea as a result of ingestingthe compound. People who use the compound should usereasonable precaution in handling the material, taking carenot to inhale or ingest it.


‘‘About Epsom Salt.’’ Epsom Salt Council.http://www.epsomsaltcouncil.org/about_epsom_salt.htm(accessed on October 14, 2005).

Words to Know

ANHYDROUS Form of a compound that lacksany water of hydration.

CENTRIFUGING A method of separating thecomponents of a mixture by spinning themixture at a high rate of speed. Centrifu-gal force acts differently on each compo-nent of the mixture, causing them toseparate from each other.

ELECTROPLATING A process by which a thinlayer of one metal is deposited on top of asecond metal by passing an electric currentthrough a solution of the first metal.

HYDRATE A chemical compound formedwhen one or more molecules of water is

added physically to the molecule ofsome other substance.

MORDANT A substance used in dyeingand printing that reacts chemically withboth a dye and the material being dyedto help hold the dye permanently to thematerial.




MAGNESIUM SULFATE

‘‘Magnesium Sulfate Anhydrous.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/m0235.htm(accessed on October 14, 2005).

Nardozzi, Charlie. ‘‘Fertilize with Epsom Salts.’’ Do It Yourself.com.http://doityourself.com/fertilizer/fertilizeepsomsalts.htm(accessed on October 14, 2005).


MAGNESIUM SULFATE

OTHER NAMES:Hexahydrothymol;methylhydroxyiso-

propylcyclohexane;peppermint camphol

FORMULA:CH3C6H9 (C3H7)OH


oxygen


STATE:Solid


MELTING POINT:41�C to 43�C (106�F to

109�F)



water; very soluble inalcohol, chloroform,

and ether

Menthol

KE

YF

AC

TS

OVERVIEW

Menthol (MEN-thol) occurs naturally in the peppermintplant. In pure form it occurs as a white crystalline mate-rial with a cooling taste and odor. Peppermint is one ofthe oldest known herbal remedies. Dried peppermintleaves have been found in Egyptian pyramids dating toat least 1000 BCE, and its use among the Greeks andRomans in cooking and medical preparations is well known.Peppermint was not introduced to western Europe, however,until the eighteenth century, when it was used to treat avariety of ailments ranging from toothaches to morningsickness. It was first brought to the United States about acentury later.

HOW IT IS MADE

Peppermint oil is extracted from the leaves of the pep-permint plant, Mentha piperita, by steam distillation, bywhich various oils in the plant are separated from each other.

HH

C

OCC

CH3

CH3

H3C

H

H H

HH

H

H

H

HC

CC

C


The peppermint oil is then frozen to extract the mentholfrom other components of the oil. Menthol can also be pro-duced synthetically by the reduction of thymol [(CH3)2CHC6H3

(CH3)OH] with hydrogen.

Menthol. Red atom is oxygen;white atoms are hydrogen; and

black atoms are carbon.P U B L I S H E R S R E S O U R C E G R O U P


MENTHOL


Menthol smells like mint and creates a soothing andsometimes tingling sensation when it touches the skin.Scientists theorize that menthol creates the cooling sensa-tion by triggering the same receptors on skin that tell thebody’s nerves to respond to cold temperatures.

The cooling sensation makes menthol a desirable addi-tive to aftershave lotions, skin cleansers, lotions, sore throatlozenges, and lip balms. Menthol is also used in a variety ofcosmetics applied to the skin and medications for the reliefof itching. It is also added to foods such as chewing gums andcandies to impart a mint-like flavor.

When inhaled or ingested as a lozenge, menthol can relievenasal congestion and coughs, as well as cool and numb thethroat to ease the pain of sore throats. It can also be used inointments with camphor and eucalyptus to produce cooling andantiseptic properties. These ointments can be applied to thechest and/or nostrils to clear the nose and reduce coughing.One of the most famous menthol-containing products is Vicks�

VapoRub, which is used to relieve coughs and congestion.

Although menthol is soothing and cooling in small quanti-ties, it produces a quite different effect in larger quantities.Gargling with a large amount of menthol-containing mouthwash,for example, can create an unpleasant burning sensation.

Although menthol has been classified as a ‘‘generallyrecognized as safe’’ (GRAS) product and approved for use infoods by the U.S. Good and Drug Administration, some sideeffects have been reported. On contact with the skin,

Interesting Facts

• Menthol was first added tocigarettes in the early1900s to make a coolertasting product. Tobaccocompanies claimed thatmenthol cigarettes wereless irritating to the throat

and an effective way oftreating sore throats.Today, about 25 percent ofall cigarettes sold in theUnited States are mentho-lated.


MENTHOL

menthol may cause irritation. Ingesting large quantities cancause abdominal pain, nausea, vomiting, dizziness, drowsi-ness, and even coma. These effects are more likely to occur ininfants and children than in adults.


‘‘Cool Menthol 1’’ and ‘‘Cool Menthol 2.’’ Great Moments in Science.http://www.abc.net.au/science/k2/moments/s537539.htm andhttp://www.abc.net.au/science/k2/moments/s537548.htm(accessed on October 12, 2005).

Cummings, Linda Scott. ‘‘M2258 Menthol.’’ Paleoresearch Institute.http://www.paleoresearch.com/MSDS/MENTHOL%20 %20SIGMA%20CHEMICAL%20 %2005 19 1997.htm (accessed onOctober 12, 2005).

‘‘Menthol and Tobacco Smoking.’’http://goodhealth.freeservers.com/MethTobaccoIntro.html(accessed on October 12, 2005).

‘‘Menthol Its Chemistry and Many Uses.’’http://goodhealth.freeservers.com/MenthUseThisOne.htm(accessed on October 12, 2005).

Travis, J. ‘‘Cool Discovery: Menthol Triggers Cold Sensing Protein.’’Science News (February 16, 2002): 101 102.

See Also Camphor

Words to Know


REDUCTION The chemical reactionin which oxygen is removed from

a substance or electrons are added toa substance.



MENTHOL

OTHER NAMES:Mercuric sulfide;

cinnabar; vermillion;Chinese red

FORMULA:HgS

ELEMENTS:Mercury, sulfur


STATE:Solid


MELTING POINT:Data differ

significantly; seeOverview


SOLUBILITY:Insoluble in water,alcohol, and most

acids; soluble inaqua regia

Mercury(II) Sulfide

KE

YF

AC

TS

OVERVIEW

Mercury(II) sulfide (MER-kyuh-ree two SUL-fide) occurs intwo forms, red and black. Red mercury(II) sulfide, commonlyknown as cinnabar, begins to change color when heated totemperatures of about 250�C (500�F) and converts to the blackform at 386�C (727�F). If heated further, it sublimes (changesdirectly from a solid to a gas without first melting) at 583.5�C(1,082�F). If allowed to cool, it then reverts to its originalreddish color. Black mercury(II) sulfide goes through a similarprocess, changing to its red counterpart before melting at583.5�C (1,082�F). Some authoritative resources give signifi-cantly different temperatures for these transitions. Redmercury(II) sulfide occurs naturally as the mineral cinnabar,while black mercury(II) sulfide occurs only rarely in nature, thenas the mineral metacinnabar (meaning ‘‘similar to cinnabar’’).

HOW IT IS MADE

Red mercury(II) sulfide is obtained commercially fromthe mineral cinnabar. The compound can also be made

S Hg


synthetically by heating mercury and sulfur together in agaseous state or by heating mercury with a solution ofpotassium pentasulfide (K2S5). The compound produced byeither of these methods is commonly known as English ver-million, or simply, vermillion. The term vermillion is gener-ally reserved for any form of mercury(II) sulfide that hasbeen made synthetically rather than extracted from cinna-bar. Other methods for the preparation of both red and blackmercury(II) sulfide are available. For example, the black formcan be produced by reacting sodium thiosulfate (Na2S2O3)with sodium mercurichloride (Na2HgCl4).


The earliest records of the use of mercury(II) sulfide byhumans date to about the third millennium BCE in China,where the compound was used to cure diseases, relieve pain,as a narcotic and an antiseptic, and as a preservative. Chi-nese alchemists referred to the compound as ‘‘celestial

Mercury Sulfide. Turquoiseatom is mercury and yellow

atom is sulfur. Stick is a doublebond. P U B L I S H E R S R E S O U R C E

G R O U P


MERCURY(II) SULFIDE

sands’’ or ‘‘god’s sand’’ and believed that it could transformbase metals, like iron and lead, into precious metals, likesilver and gold.

Today, the primary use of mercury(II) sulfide is in theproduction of metallic mercury. The sulfide is heated in afurnace to temperatures of 600�C to 700�C (1,100�F to1,300�F), resulting in the formation of sulfur dioxide andmercury metal. In a second process, the sulfide is treatedwith lime (CaO), resulting in the formation of mercury metal,calcium sulfide (CaS) and calcium sulfate (CaSO4).

The other major use for mercury(II) sulfide, in either redor black form, is as a pigment in artists’ paints, for coloringpaper and plastics, and for marking linen. The black form isalso used as a pigment for the coloring of rubber, horn, andother materials. Red mercury(II) sulfide finds some use alsoas an antibacterial agent.

Both forms of mercury(II) sulfide are highly toxic byingestion, inhalation, or absorption through the skin. Someof the symptoms resulting from mercury(II) sulfide poison-ing include inflammation and itching of the skin; redness,

Interesting Facts

• Women used vermillionduring the Renaissanceperiod to redden their lipsand cheeks.

• Mercury(II) sulfide is acomparatively expensivecompound, selling in late2005 for about 1,600dollars per 100 grams.

Words to Know


AQUA REGIA A combination of concentratednitric acid and hydrochloric acid.


MERCURY(II) SULFIDE

itching, burning, and watering of the eyes; excessive saliva-tion; pain when chewing; gingivitis with loosening of teeth;and mental disturbances, such as loss of memory, insomnia,irritability, and vague fears of depression. Anyone who hasbeen exposed to mercury(II) sulfide and experiences suchsymptoms requires immediate medical attention.


Liu, Guanghua. ‘‘Chinese Cinnabar.’’ The Mineralogical Record

(January February 2005): 69 80.

‘‘The Mineral Cinnabar.’’ Amethyst Galleries.http://mineral.galleries.com/minerals/sulfides/cinnabar/cinnabar.htm (accessed on October 14, 2005).


MERCURY(II) SULFIDE

OTHER NAMES:Marsh gas; methyl

hydride

FORMULA:CH4


COMPOUND TYPE:Hydrocarbon; alkane

(organic)

STATE:Gas



(�296.45�F)

BOILING POINT:�161.48�C

(�322.63�F)


in water and acetone;soluble in ethylalcohol, methyl

alcohol, and ether

Methane

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OVERVIEW

Methane (METH-ane) is a colorless, odorless, tasteless,flammable gas that is less dense then air. It is the primarycomponent of natural gas. Methane is the simplest of allhydrocarbons, organic compounds that contain carbon andhydrogen and no other elements.

HOW IT IS MADE

Methane formed millions of years ago from microscopicunderwater plants and bacteria that dropped to the bottom ofthe ocean when they died. Over millions of years, they werecrushed and heated by the pressure of layers of sand, dirt,and other materials that accumulated on top of them. Themineral components of the undersea mud gradually turnedinto a type of rock known as shale. Some of the organiccomponents turned into natural gas, which is mostlymethane. The natural gas became trapped in porous rockscalled reservoir rocks and in larger pockets of the rock calledreservoirs or geologic traps. Natural gas is now found in

HH

HHC


pockets by itself, but is more commonly found floating ontop of petroleum lakes in underground reservoirs.

Methane is also found in conjunction with pockets of coal.The largest reserves of natural gas in the United States are inTexas, Alaska, Oklahoma, Ohio, and Pennsylvania. Oil and gascompanies remove natural gas from the ground by drilling.They then purify the natural gas by separating the compo-nents of which it is made, such as methane, ethane, propane,and butane. After isolation from natural gas, methane is oftenliquefied, which makes its easier to store and transport.

Although abundant supplies of methane exist, it can alsobe produced synthetically. For example, the reaction betweensteam and hot coal results in the formation of synthesis gas,a mixture of hydrogen and carbon monoxide. When thismixture is passed over a catalyst containing nickel metal,methane is formed. A very similar process, called the Sabatierprocess, uses a mixture of hydrogen and carbon dioxide,rather than carbon monoxide, also resulting in the formation

Methane. Black atom iscarbon and white atoms are




METHANE

of methane. Finally, methane produced during the anaerobicdecomposition of manure can be captured and purified.


When methane burns, it releases a large amount ofenergy, making it useful as a fuel. Humans have knownabout methane as a source of energy for thousands of years.Temples in the ancient world often burned ‘‘eternal flames’’that may have been fueled by natural gas. In the early nine-teenth century, people began using natural gas as a lightsource. Once oil was discovered in the 1860s, however, itsuse, and the electricity produced by burning oil, becamemuch more popular, and people abandoned natural gas as afuel except for limited use in cooking.

Natural gas has become more popular in recent yearsbecause its use results in less pollution than petroleum andother fossil fuels. Some uses include heating homes, offices,and factories; powering room heaters and air conditioners;and operating home appliances such as water heaters andstoves.

Scientists are now exploring other uses for methane andnatural gas with the hope that they might eventuallybecome the most important fuels used by humans. Methanehas some advantages over petroleum and coal as a fuel. It

Interesting Facts

• Methane is sometimes calledmarsh gas because it formsin swamps as plants andanimals decay under water.

• Methane is odorless, butgas companies add tracesof sulfur-containingcompounds with strongodors so that people willbe able to smell gas leaks

and avoid suffocation orexplosions.

• Some experts estimatethat enough methane ispresent in the Earth’ssurface to last as muchas two hundred years,although extraction ofsome methane resourcesmay prove to be difficult.


METHANE

burns more cleanly than either of these other fossil fuels,producing only carbon dioxide and water as combustionproducts. Some experts believe that methane could be usedas a power source of fuel cells, cells that burn hydrogen toproduce electricity. Adding natural gas to oil- or coal-firedburners would also help reduce the greenhouse gas emis-sions of these appliances.

In addition to its applications as a fuel, methane is usedin the manufacture of a number of organic and inorganiccompounds. For example, ammonia, which is the tenth mostimportant chemical compounds in the United States, basedon quantity produced, is made from hydrogen and nitrogengases. Over 90 percent of the hydrogen used to make ammo-nia is now obtained by reacting methane with water at hightemperatures over a catalyst of iron oxide (Fe3O4). Othercompounds produced from methane include methanol(methyl alcohol), acetylene (ethyne), formaldehyde (metha-nal), hydrogen cyanide, carbon tetrachloride, chloroform,methylene chloride, and methyl chloride.

Methane is not toxic, but it can cause suffocation byreducing or eliminating the oxygen a person needs tobreathe normally. The primary hazard posed by the gas isits flammability and explosive tendency.


‘‘Chemical of the Week: Methane.’’ Science Is Fun.http://scifun.chem.wisc.edu/chemweek/methane/methane.html (accessed on October 17, 2005).

‘‘Methane.’’ U.S. Environmental Protection Agency.http://www.epa.gov/methane/ (accessed on October 17, 2005).

Words to Know

ANAEROBIC Describing a process that takesplace in the absence of oxygen.

GREENHOUSE GAS One of several gases,including carbon dioxide and ozone, thatcauses the greenhouse effect on Earth.


METHANE

‘‘Methane Madness: A Natural Gas Primer.’’ The Coming Global OilCrisis.http://www.oilcrisis.com/gas/primer/ (accessed on October 17,2005).

Sherman, Josepha, and Steve Brick. Fossil Fuel Power. Mankato,MN: Capstone Press, 2003.

See Also Propane


METHANE

OTHER NAMES:Methanol; wood

alcohol; wood spirit;carbinol

FORMULA:CH3OH


oxygen


STATE:Liquid




SOLUBILITY:Miscible with water,ethyl alcohol, ether,

acetone, and manyother organic

solvents

Methyl Alcohol

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OVERVIEW

Methyl alcohol (METH-uhl AL-ko-hol) is a clear, colorless,flammable, toxic liquid with a slightly alcoholic odor andtaste. Methyl alcohol is the simplest alcohol, a family oforganic compounds characterized by the presence of one ormore hydroxyl (-OH) groups.

HOW IT IS MADE

Methyl alcohol occurs naturally in plants and animals,including humans, as the product of metabolic reactions thatoccur in all organisms. It also occurs in the atmosphere as theresult of the decomposition of dead organisms in the soil. Noneof these sources is utilized for the commercial production ofmethyl alcohol. Instead, the primary method for the prepara-tion of methyl alcohol is to react carbon monoxide with waterat a temperature of about 250�C (480�F) and pressures of 50 to100 atmospheres over a mixed catalyst of copper, zinc oxide,and aluminum oxide. Efforts are being made to develop othermethods of synthesizing methyl alcohol. In one process, for

HO CH3


example, simple hydrocarbons, such as methane, are oxidizedover a catalyst of molybdenum metal to produce the alcohol.None of the experimental methods developed for the produc-tion of methyl alcohol can yet compete with the traditionalcarbon monoxide-hydrogen process, however.


Consumption of methyl alcohol in the United States for2005 reached about 12 billion liters (3 billion gallons). Thelargest demand for the compound was in the production ofMTBE (methyl-tert-butyl ether), a gasoline additive used toimprove the efficiency with which a fuel burns and to reducepollutants released to the atmosphere. Demand for the addi-tive increased rapidly after the U.S. Congress passed the 1990Clean Air Act Amendments requiring significant reductions inthe release of certain pollutants into the atmosphere. A decadelater, however, serious questions were being raised about pos-sible serious environment dangers posed by MTBE releasedinto the soil. In the last few years, enthusiasm for the use ofMTBE has begun to disappear and a number of states haveadopted bans on its use as a gasoline additive. As a result ofthese actions, the demand for methyl alcohol in producingMTBE has dropped dramatically in the last few years.

Methyl alcohol. Red atom isoxygen; white atoms are

hydrogen; and black atom iscarbon. P U B L I S H E R S


METHYL ALCOHOL


The next most important demand for methyl alcohol is asa raw material in the synthesis of many important organiccompounds, including formaldehyde; acetic acid; chloro-methanes, compounds in which the hydroxyl group and/orone or more hydrogen has been replaced by fluorine, chlor-ine, bromine, and/or iodine; methyl methacrylate, a com-pound from which acrylic plastics are made; methylamines,the source of another important class of plastics, dimethylterephthalate, the monomer for yet another class of plastics;and other products.

Relatively small quantities of methyl alcohol are used ina number of other applications, including:

• As a solvent for household and industrial products;

• As a deicing agent;

• In the preparation of embalming fluids;

• As a softening agent for plastics;

• As a fuel for camp stoves, soldering torches, and racecars;

• In paint removing products;

• As an antifreeze and windshield washing fluid; and

• In the manufacture of a number of pharmaceuticals,including streptomycin, vitamins, and hormones.

Interesting Facts

• At one time, the primarymethod for makingmethyl alcohol was toheat wood in a closedspace, accounting for thecompound’s common andpopular name of ‘‘woodalcohol.’’

• Methyl alcohol was firstisolated, although not in a

pure form, by the Englishchemist and physicistRobert Boyle (1627–1691)although the compoundwas not synthesized foranother two centuries. Itwas then produced by theFrench chemist PierreEugene Marcelin Berthelot(1827–1907).


METHYL ALCOHOL

Methyl alcohol poses both safety and health hazards. It ishighly flammable and, with the appropriate mixture of air,explosive. It is also very toxic by ingestion, producing avariety of effects that include blurred vision, headache, dizzi-ness, drowsiness, and nausea. Although a fatal dose is usuallyin the range of 100 to 250 mL, cases have been reported inwhich a person has died after consuming less than 30 mL ofthe compound. People who work with methyl alcohol in theirjobs, including bookbinders, dyers, foundry workers, gilders,hat makers, ink makers, laboratory technicians, painters,photoengravers, and chemical workers, are especially at riskfrom methanol poisoning. The ready availability of the com-pound and products in which it is an ingredient means thateveryone who uses such products should be aware of thehealth risks involved in its use. Medical attention is requiredimmediately in case of the ingestion of methyl alcohol.


‘‘Material Safety Data Sheet: Methyl Alcohol, Reagent ACS, 99.8%(GC).’’ Department of Chemistry, Iowa State University.http://avogadro.chem.iastate.edu/MSDS/methanol.htm(accessed on October 17, 2005).

McGrath, Kimberley A. ‘‘Methanol.’’ World of Scientific Discovery,

2nd edition. Detroit, MI: Gale, 1999.

Words to Know

METABOLISM A biological process thatincludes all of the chemical reactions thatoccur in cells by which fats, carbohydrates,and other compounds are broken down toproduce energy and the compoundsneeded to build new cells and tissues.

MISCIBLE able to be mixed; especially appliesto the mixing of one liquid with another.

MONOMER A small molecule used inpolymerization reactions to produce

very large molecules in which themonomer is repeated hundreds orthousands of times.

SOLVENT A liquid that dissolves anothersubstance.


METHYL ALCOHOL


‘‘Methanol.’’ U.S. Environmental Protection Agency. TechnologyTransfer Network, Air Toxics Website.http://www.epa.gov/ttn/atw/hlthef/methanol.html (accessedon October 17, 2005).

Salocks, Charles, and Karlyn Black Kaley. ‘‘Methanol.’’ TechnicalSupport Document: Toxicology Clandestine Drug Labs/Methamphetamine, Volume 1, Number 10.http://www.oehha.ca.gov/public_info/pdf/TSD%20Methanol%20Meth%20Labs%2010’8’03.pdf (accessed on October 17, 2005).

U. S. Department of Health and Human Services. ‘‘Methanol Toxicity.’’ American Family Physician (January 1993): 163 171.

See Also Carbon Monoxide; Formaldehyde


METHYL ALCOHOL

OTHER NAMES:Methanethiol;

mercaptomethane;thiomethyl alcohol;methyl sulfhydrate

FORMULA:CH3SH


sulfur

COMPOUND TYPE:Mercaptan; thiol

(organic)

STATE:Gas





water; soluble inethyl alcohol and

ether

Methyl Mercaptan

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OVERVIEW

Methyl mercaptan (METH-uhl mer-KAP-tan) is a colorless,highly flammable, foul-smelling gas with the odor of rottencabbage released from decaying animal and vegetable matter.It is also produced in the intestinal tract by the action ofbacteria on a variety of proteins known as the albumins.

Methyl mercaptan belongs to a class of organic com-pounds called mercaptans or thiols in which one or moresulfhydryl (-SH) groups are attached to a carbon atom. Methylmercaptan has only one carbon atom, but some mercaptanscontain up to twenty carbon atoms. Like methyl mercaptan,other mercaptan compounds are known for their disagreeableodors. For example, allyl mercaptan has the characteristicsmell of garlic, while butyl mercaptan occurs in the spray thatskunks release to protect themselves from predators.

HOW IT IS MADE

Methyl mercaptan is made by the direct reaction betweenmethanol (methyl alcohol; CH3OH) and hydrogen sulfide gas

S HH3C


(H2S). The hydroxyl group (-OH) from the alcohol combineswith one hydrogen from hydrogen sulfide to form water,leaving the methyl mercaptan behind as the major product.


Methyl mercaptan’s primary use is in the synthesis ofother organic compounds, especially pesticides, fungicides,jet fuel components, plastics, and the amino acid methionine[CH3SCH2CH2CG(NH2)COOH]. Amino acids are the building-block compounds from which proteins are made. The com-pound is also used as an odorant, a substance with a notice-able and usually offensive odor added to odorless compoundsfor the purpose of safety. For example, propane and naturalgas are two widely used gases that are very flammable, butodorless. If these gases were used without having an odorantadded, consumers might not be aware of a leak until the gascaught fire or exploded. The presence of the odorant, such asmethyl mercaptan, makes a leak obvious and allows it to berepaired before an accident occurs.

In spite of the fact that it is a natural product, methylmercaptan is a health and environmental risk. When inhaled,it can irritate the eyes, skin, nose, throat, and lungs, producing

Methyl mercaptan. Whiteatoms are hydrogen; black atomis carbon; and yellow atom is

sulfur. P U B L I S H E R S R E S O U R C E

G R O U P


METHYL MERCAPTAN

dizziness, headache, vomiting, muscle weakness, and loss ofcoordination. In large concentrations, methyl mercaptan candamage the central nervous system, leading to respiratoryfailure and even death. The U.S. Occupational Safety andHealth Administration (OSHA) has set maximum exposurelimits at 20 milligrams of the compound per cubic meter ofair per eight-hour work day.


‘‘Bad Breath: What Usually Is the Source of a Person’s BadBreath?’’ Animated Teeth.com.http://www.animated teeth.com/bad_breath/t3_causes_of_halitosis.htm (accessed on October 17, 2005).

Interesting Facts

• Methyl mercaptan may beresponsible for some of theunpleasant odors producedby humans, such as badbreath, flatulence, andstinky feet. When bacteriaattack proteins in the body,they release several gases,methyl mercaptan amongthem. These gases areresponsible for bad breathand periodontal disease(inflammation of thegums) in the mouth, andunpleasant odors fromother parts of the body.For example, old or dirtysocks and shoes are idealbreeding sites for thebacteria responsible forthe production of methylmercaptan and similarfoul-smelling organiccompounds. One popular

product designed to dealwith this problem is shoeinsoles that containactivated charcoal.Activated charcoal is aform of charcoal consistingof very fine grains thatabsorbs large volumes ofgases, such as methylmercaptan and itsbad-smelling cousins.

• Why does eating asparagusproduce bad-smellingurine? Asparagus containsthe amino acid methionine,which is metabolized in thebody to produce methylmercaptan. The peculiarodor of urine producedafter consuming asparagusis caused by the methylmercaptan excreted fromthe body in urine.


METHYL MERCAPTAN

Emsley, John. ‘‘Molecules at an Exhibition.’’http://www.nytimes.com/books/first/e/emsley molecules.html(accessed on October 17, 2005).

‘‘Safety Data Sheet: Methyl Mercaptan.’’ Air Liquide.http://www.airliquide.com/safety/msds/en/083_AL_EN.pdf(accessed on October 17, 2005).

‘‘ToxFAQs for Methyl Mercaptan.’’ Agency for Toxic Substancesand Disease Registry.http://www.atsdr.cdc.gov/tfacts139.html (accessed on October17, 2005).


METHYL MERCAPTAN

OTHER NAMES:MTBE; see Overview

for additional names

FORMULA:(CH3)3COCH3


oxygen

COMPOUND TYPE:Ether

STATE:Liquid




SOLUBILITY:Soluble in water; very

soluble in ethylalcohol and ether

Methyl-t-butyl Ether

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OVERVIEW

Methyl-t-butyl ether (METH-el TER-she-air-ee BYOO-tillEE-thur) is a volatile (evaporates easily), colorless, flammableliquid that forms an azeotropic mixture with water. Azeotro-pic mixtures are combinations of two or more liquids thatboil at the same temperature and, therefore, cannot be easilyseparated from each other.

MTBE was first synthesized in the 1960s by researchersat the Atlantic Richfield Corporation (now ARCO) as an addi-tive designed to increase the octane number (fuel efficiency)of gasoline. The compound was created as a replacement fortetraethyl lead (Pb(C2H5)4), which had long been added togasolines to improve their octane number. Tetraethyl leadwas commonly called simply ‘‘lead.’’ From 1973 until 1996,lead was gradually removed from most gasoline because of itsdangerous environmental and health effects. In 1990, a newuse for MTBE was found. In that year, legislation passed bythe U.S. Congress required that changes be made in thecomposition of gasoline so that it would burn more cleanly

C

O

CH3 CH3

CH3

H3C


and release fewer pollutants into the atmosphere. One wayfor companies to meet this regulation was to add oxygenatesto their gasoline. Oxygenates are chemical compounds thatcontain oxygen. They react with fuels, giving off their oxy-gen and increasing the efficiency with which the fuels burn.

MTBE rapidly became a very popular chemical in theautomotive fuel industry. Production rose at a rate of about7 percent per year in the 1980s. It increased from about 500million kilograms (1 billion pounds) in 1983 to about 3 billionkilograms (6 billion pounds) in 1990. In that year, it rankedtwenty-fourth among all chemicals produced in the UnitedStates.

Methyl t butyl Ether (MTBE).

Black atoms are carbon; redatom is oxygen; white atomsare hydrogen. All sticks aresingle bonds. P U B L I S H E R S



METHYL T BUTYL ETHER

In the early 1990s, however, MTBE began showing up ingroundwater in a number of states. Upon investigation,researchers discovered that MTBE had leaked out of under-ground tankers, had been spilled during transportation, andhad escaped into the environment in other ways. It sank intothe ground, where it mixed with groundwater forming azeotro-pic mixtures that could not be easily separated. The compoundwas found in wells, lakes, streams, and public water supplies.

These findings raised concerns because some expertsbelieve that MTBE is a health hazard to humans and otheranimals. Although strong evidence is not yet available, manyauthorities believe that MTBE is a carcinogen and that itmay be responsible for other health problems and damage tothe environment. These concerns have led to legislative andadministrative action banning or limiting the use of MTBEin gasoline. The first such action occurred in 1999 whenGovernor Gray Davis of California announced a program tocut back and eventually eliminate the use of MTBE in thestate. A year later, the U.S. Environmental Protection Agencyannounced similar plans for the nation as a whole.

MTBE is also known by the following names: Methyl-tert-butyl ether; t-butyl-methyl ether; and tert-buty-methyl ether.

HOW IT IS MADE

MTBE is made by reacting methanol (methyl alcohol;CH3OH) with isobutylene (isobutene; CH3C(CH3)=CH3). The

Interesting Facts

• Virtually all of the MTBEproduced is used as a fueladditive. If proposed bansand limitations go intoeffect, there will no longerbe any demand for thechemical. As such, produc-tion is likely to drop nearly

to zero. One company thatsurveys chemical produc-tion predicts that the pro-duction of MTBE is likelyto decrease at the rate ofabout 8 percent per yearover the foreseeablefuture.



formula for this reaction is CH3OH + CH3C(CH3)=CH2 !(CH3)3COCH3.


More than 99 percent of the MTBE produced is used as agasoline additive. The remaining quantity is used as a sol-

vent and in the production of other chemical compounds.

MTBE is a mild irritant to the skin, eyes, and respiratorysystem. In larger doses, it may cause more serious problems,including nausea, vomiting, diarrhea, gastrointestinal pro-

blems, headache, dizziness, and loss of balance and coordina-tion. In extreme cases, MTBE may produce severe lung

damage, respiratory failure, convulsions, respiratory arrest(breathing stops), unconsciousness, coma, and death. The

compound has been found to cause cancer in laboratoryanimals. No similar studies are available for humans, but

experts tend to agree that MTBE is likely carcinogenic inhumans also.


‘‘Groundwater Protection.’’ American Petroleum Institute.http://api ep.api.org/environment/index.cfm?objectid=9EC44CD5 E167 49C4 8EBE7B354E4B3CD9&method=display_body&er=1&bitmask=002008008000000000 (accessed on December 29, 2005).

Words to Know

AZEOTROPIC MIXTURE A combination oftwo or more liquids that boil at thesame temperature and, therefore,cannot be easily separated from eachother.


OXYGENATES Chemical compounds thatcontain oxygen.

SOLVENT A substance that is able todissolve one or more other substances.

VOLATILE Able to turn to vapor easily ata relatively low temperature.



‘‘Methyl tert Butyl Ether (MTBE) and Other Gasoline Oxygenates.’’U.S. Geological Survey.http://sd.water.usgs.gov/nawqa/vocns/mtbe.html (accessed onDecember 29, 2005).

‘‘Methyl Tertiary Butyl Ether (MTBE).’’ U.S. EnvironmentalProtection Agency.http://www.epa.gov/mtbe/ (accessed on December 29, 2005).

‘‘MTBE (methyl tert butyl ether).’’ The Innovation Group.http://www.the innovation group.com/welcome.htm (accessedon December 29, 2005).



OTHER NAMES:Sodium glutamate;

glutamic acid mono-sodium salt; MSG

FORMULA:COOH(CH2)2CH(NH2)-

COONa


sodium

COMPOUND TYPE:Organic salt

STATE:Solid



decomposes whenheated


SOLUBILITY:Very soluble in water

and ethyl alcohol

MonosodiumGlutamate

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OVERVIEW

Monosodium glutamate (mon-oh-SOH-dee-yum GLOO-tuh-mate) is an almost completely odorless white crystallinepowder. It is the sodium salt of a common amino acid calledglutamic acid. An organic salt is a compound formed when aninorganic base, such as sodium hydroxide, reacts with anorganic acid, such as glutamic acid.

Monosodium glutamate has been available as a commer-cial product for about a century. But the compound has beenused in its natural form for much longer. The ancient Greeksand Romans used fish sauce, which contains glutamic acid asa natural ingredient, in their cooking. Later Europeans alsoused a form of the substance in a product known as garum.

The German chemist Karl Heinrich Ritthausen (1826-1912) first identified glutamic acid in wheat gluten in 1866,and its chemical structure was first identified in 1890 by theGerman chemist Wolff. Then in 1908, the Japanese chemistKikunae Ikeda (1864–1936) discovered the flavor-enhancingproperties of glutamic acid. He found in seaweed broth a

C

O

N

H

H

H C

CO

HH

H

H

H

Na+

OH

O-

C

C


compound, later identified as glutamic acid, responsible forthe unique taste of cheese, meat, and tomatoes. The com-pound was not sweet, salty, sour, or bitter, but instead hada rich meaty taste. He named the unusual flavor umami.Ikeda used glutamic acid crystals to make a seasoning, whichhe then patented. Like salt and sugar, it was readily solublein water and could be stored for long periods of time withoutclumping. The seasoning was actually the sodium salt ofglutamic acid, monosodium glutamate, first sold commer-cially in Japan under the name Ajinomoto, which means‘‘essence of taste.’’ The product was introduced into the UnitedStates shortly after World War II, and the U.S. Food and DrugAdministration approved its use as a food additive in 1958.

HOW IT IS MADE

Glutamic acid in the form of glutamate exists in twoforms: bound and free. The term bound glutamate refers tothe glutamic acid that has combined with other amino acidsto form proteins. The term free glutamate refers to the acidradical COOH(CH2)2CH(NH2)COO- formed when a single mole-cule of glutamic acid loses one hydrogen ion. Foods such as

Monosodium glutamate. Redatoms are oxygen; white atomsare hydrogen; black atoms arecarbon; blue atom is nitrogen;and turquoise atom is sodium.

Gray sticks indicate doublebonds. P U B L I S H E R S R E S O U R C E

G R O U P


MONOSODIUM GLUTAMATE

tomatoes, mushrooms, and cheeses are naturally high inglutamate, which is responsible for their strong flavors. Onlythe free form of glutamate enhances food flavors. In thehuman body, glutamate is a nonessential amino acid foundin the brain, muscles, kidneys, liver, and other organs.

Monosodium glutamate is made commercially by thehydrolysis of the waste products of beet sugar refining,wheat, or corn gluten. Hydrolysis is the process by which acompound reacts with water to form two new compounds. Inthe preparation of monosodium glutamate, water breaksapart the proteins present in the raw materials used (suchas wheat or corn gluten), freeing the amino acids of whichthey are made. The glutamic acid present in the proteins canthen be separated from other amino acids present, then iso-lated and purified. Monosodium glutamate can also be madeby a very similar process in which bacterial fermentation isused to break proteins down into their component parts, ofwhich glutamic acid is one, a process which is now theprimary means of production for the compound.


The sole use of monosodium glutamate is as a flavorenhancer in food products. Annual worldwide consumptionof the additive has been estimate at about 1 million metrictons (1.1 million short tons). It is used primarily in a varietyof Asian foods, including soups, canned foods, and processedmeats.

Monosodium glutamate is considered safe for humanconsumption. It is on the U.S. Food and Drug Administra-tion’s Generally Recognized as Safe (GRAS) list. The GRAS

Interesting Facts

• The flavor-enhancing qua-lities of monosodium glu-tamate are a function ofits concentration in foods.At concentrations of lessthan about 0.5 percent, it

enhances the flavor of afood product. At greaterconcentrations, it beginsto make the food producttaste bad.



list contains chemicals that have never been tested scienti-fically for safety, but are generally believed to be safe forhuman consumption. In 1987, health experts from the UnitedNations and the World Health Organization reviewed morethan two hundred studies on MSG and determined that thecompound is a safe food additive when used at customarylevels.

In spite of these studies and rulings, many people believethat monosodium glutamate can have harmful health effects.They say that eating foods that include MSG can cause head-ache, nausea, sweating, rapid heartbeat, a burning sensationin the back of the neck, and/or tightness in the chest. Thusfar, scientific studies have been unable to confirm the asso-ciation of MSG with these symptoms.

Researchers theorize that the reactions may be the resultof allergies to certain ingredients in the foods. In particular,they are likely to occur among people who have specificallergies to monosodium glutamate or who have asthma.


‘‘The Facts on Monosodium Glutamate.’’ European Food Information Council.http://www.eufic.org/gb/food/pag/food35/food352.htm(accessed on October 17, 2005).

‘‘FDA and Monosodium Glutamate (MSG).’’ U.S. Food and DrugAdministration.http://www.cfsan.fda.gov/~lrd/msg.html (accessed on October17, 2005).

‘‘Glutamate Facts, Information and On Line Services.’’ International Glutamate Information Service.http://www.glutamate.org (accessed on October 17, 2005).

‘‘L glutamic Acid, Sodium Salt.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/g3975.htm(accessed on October 17, 2005).



OTHER NAMES:N,N-diethyl-m-

toluamide; DEET

FORMULA:C6H4(CH3)CON(C2H5)2


nitrogen, oxygen


STATE:Liquid



BOILING POINT:160�C (320�F) at 19

mm Hg pressure


ether, benzene, andmost other organic

solvents

N,N-Diethyl-3-Methyl-benzamide

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OVERVIEW

N,N-diethyl-3-methylbenzamide (en-en-dye-ETH-el-three-METH-el-ben-ZA-mid) is the most commonly used insectrepellant in the world. It is probably better known by itscommon name of DEET. DEET is applied to the skin andclothing to ward off biting insects such as mosquitoes, ticks,chiggers, and fleas. Although it does not kill insects, DEETrepels them for several hours after being applied.

N,N-diethyl-3-methylbenzamide is a colorless amberliquid with a faint odor. The compound can exist in any oneof three isomers in which the two groups attached to thebenzene ring are next to each other (ortho), separated by onecarbon (meta), or opposite each other in the ring (para).Although all three isomers are effective as insect repellants,the meta isomer is more effective than the ortho and paraisomers and constitutes about 95 percent of the commercialproduct.

DEET was discovered by researchers at the U.S. Depart-ment of Agriculture and patented by the U.S. Army in 1946

NC

O

H

H

H

H

C

H

H

H

C H

C

C

C

C

CC

CH3

CH3

CH3


for use on military personnel working in insect-infestedareas. It was not made available to the general public until1957. Experts now regard DEET as the ‘‘gold standard’’ ofinsect repellants. It is available in a variety of formulations,including solutions, lotions, creams, gels, aerosol and pumpsprays, and impregnated towelettes under names such asHour Guard 8 and Hour Guard 12, DEET Plus, Sawyers Gold,Off (in many varieties), Ben’s Backyard and Ben’s Wilder-ness, Cutter (in many varieties), and Repel (in manyvarieties).

HOW IT IS MADE

DEET is made commercially by treating m-toluic acid(C6H4CH3COOH) with thionyl chloride (SOCl2). The productof this reaction, m-toluoyl chloride (C6H4CH3COOCl) is thentreated with diethylamine (C2H5)2NH) to obtain N,N-diethyl-3-methylbenzamide.

N,N diethyl 3 methyl

benzamide. Red atom isoxygen; white atoms are

hydrogen; black atoms arecarbon; and blue atom is

nitrogen. Gray stick indicates adouble bond; striped sticks

show a benzene ring.P U B L I S H E R S R E S O U R C E G R O U P


N,N DIETHYL 3 METHYLBENZAMIDE


The mechanism by which DEET repels insects is notcompletely understood. Current theories suggest that thecompound blocks receptors on a mosquito’s antennae thathelp it to locate carbon dioxide and lactic acid, given off inskin perspiration and the breath. Lacking these chemicalclues, insects are unable to locate their prey (humans andother animals).

By warding off biting insects, DEET protects against thediseases they carry. Mosquitoes, for example, carry diseasessuch as malaria, one of the most serious diseases in the world,responsible for an estimated three millions deaths a year;encephalitis, an infection that causes inflammation andswelling of the brain; and West Nile virus, an organism thataffects the central nervous system and poses a serious threatto both humans and other animals. Ticks carry Lyme disease,an infection spread by the deer tick that causes a skin rash,joint pain, and flu-like symptoms that can develop into adebilitating and permanent health problem if not treatedearly.

DEET is a very safe product when used as directed. It isabsorbed rapidly through the skin, with up to 56 percent ofthe compound penetrating the skin in a six-hour period.Within twelve hours of application, DEET is metabolized bythe liver and excreted in the urine. If inhaled or swallowed,however, DEET poses serious health hazards. It may causeheadaches, seizures, and swelling of the brain, althoughthese symptoms are very rare among users of the product.Products containing DEET are not recommended on babiesunder the age of two months, and are now required by the EPA

Interesting Facts

• The U.S. EnvironmentalProtection Agency (EPA)has estimated that morethan two hundred millionpeople around the

world use productscontaining N,N-diethyl-3-methylbenzamide.



to carry a warning to avoid spraying the product directly intothe eyes or open wounds.


‘‘Basic Facts About DEET and DEET Based Insect Repellents. ’Consumer Specialty Products Association.http://www.deet.com/deet_fact_sheet.htm (accessed on October7, 2005).

‘‘DEET.’’http://www.chem.ox.ac.uk/mom/InsectRepellents/DEET.htm(accessed on October 7, 2005).

Fradin, Mark S., M.D. ‘‘Mosquitoes and Mosquito Repellants.’’Annals of Internal Medicine. June 1, 1998: 931 940. Also available online athttp://www.annals.org/cgi/content/full/128/11/931 (accessed onOctober 7, 2005).

Qiu H., H. W. Jun, and J. W. McCall. ‘‘Pharmacokinetics, formulation,and safety of insect repellent N,N diethyl 3 methylbenzamide(DEET): a review.’’ Journal of the American Mosquito Control

Association. March 1998: 12 27. Also available online athttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=98261685&dopt=Citation(accessed on October 7, 2005).

‘‘Review of the Toxicology Literature for the Topical Insect Repellent Diethyl m toluamide (DEET).’’ Department of HealthToxicology Unit (United Kingdom).http://www.advisorybodies.doh.gov.uk/pdfs/reviewofdeet.pdf(accessed on October 7, 2005).

See Also Carbon Dioxide; Lactic Acid

Words to Know

ISOMER One of two or more forms of achemical compound with the samemolecular formula, but different structural

formulas and different chemical andphysical properties.



OTHER NAMES:None

FORMULA:C10H8


COMPOUND TYPE:Aromatic hydro-carbon (organic)

STATE:Solid





soluble in ethylalcohol; very solublein ether and acetone

Naphthalene

KE

YF

AC

TS

OVERVIEW

Naphthalene (NAF-thuh-leen) is a white crystalline vola-tile solid with a characteristic odor often associated withmothballs. The compound sublimes (turns from a solid to agas) slowly at room temperature, producing a vapor that ishighly combustible. Naphthalene was first extracted fromcoal tar in 1819 by English chemist and physician John Kidd(1775–1851). Coal tar is a brown to black thick liquid formedwhen soft coal is burned in an insufficient amount of air. Itconsists of a complex mixture of hydrocarbons, similar tothat found in petroleum. Kidd’s extraction of naphthalenewas of considerable historic significance because it demon-strated that coal had other important applications than its useas a fuel. It could also be utilized as the source of chemicalcompounds with a host of important commercial and indus-trial uses. Naphthalene’s chemical structure was determinedby the German chemist Richard August Carl Emil Erlenmeyer(1825–1909). Erlenmeyer showed that the naphthalene mole-cule consists of two benzene molecules joined to each other.

C

CC

C

CC

CH

H

H

H

HH

HH

C

C

C


HOW IT IS MADE

Naphthalene occurs naturally in petroleum and coal tar.It is extracted from either by heating the raw material to atemperature of 200�C to 250�C (392�F to 482�F), producing amixture of hydrocarbons known as middle oil. The middle oilis then distilled to separate its individual components fromeach other, one of which is naphthalene. The naphthaleneproduced in this process is purified by washing it in a strongacid and then in a sodium hydroxide solution and purified bysteam distillation.


In 2000, about 100,000 metric tons (110,000 short tons)of naphthalene was produced in the United States. About 60

Naphthalene. White atoms arehydrogen and black atoms arecarbon. Gray sticks indicatedouble bonds. P U B L I S H E R S



NAPHTHALENE

percent of that amount was used for the synthesis of phtha-lic anhydride [C6H4(CO)2O], a compound used as the startingpoint in the manufacture of a host of products, including avariety of dyes, resins, lubricants, insecticides, and a numberof other products. At one time, naphthalene was used widelyas a moth repellent in mothballs and moth flakes and inthe manufacture of insecticides and fungicides. Demandfor these applications has decreased, however, with the intro-duction of a class of compounds known as the chlorinatedhydrocarbons. For example, one of those compounds, p-dichloro-benzene, is now the primary ingredient, rather than naphtha-lene, in mothballs and moth flakes.

Some other uses of naphthalene include:

• As an ingredient in the manufacture of the explosiveknown as smokeless gunpowder;

• In the manufacture of scintillation counters, devicesused to detect and measure radioactivity;

Interesting Facts

• The name ‘‘naphthalene’’comes from the Persianword naphtha, meaning‘‘oil’’ or ‘‘pitch.’’

• One use of naphthaleneis as an insecticide. None-theless, one type of insect,the Formosan termite, usesnaphthalene to build itsnests. Scientists have notyet determined the sourcefrom which the termitesget naphthalene or whythey are immune to itsotherwise toxic properties.

• Naphthalene becomesan environmentalcontaminant when it

leaches into the soil. In2003, however, scientistsdiscovered bacteriacapable of decomposingnaphthalene in the soil,reducing the environmentalhazards it poses.

• One of the most terribleweapons used during theVietnam War of the 1960sand 1970s was a mixture ofnaphthalene and palmitatecalled napalm that ignitedand burned at a very hightemperature causingwidespread destructionof plant life, structures,and human life.


NAPHTHALENE

• In the production of lubricants;

• In the manufacture of various types of dyes and color-ing agents;

• As an antiseptic and antihelminthic (a substance usedto kill disease-causing worms);

• As a deodorant in toilets, diaper pails, and other set-tings; and

• As a preservative.

Naphthalene can be toxic by ingestion, inhalation, orabsorption through the skin when humans are exposed to itin more than a passing way. In small amounts it may producesymptoms such as nausea, vomiting, headache, and fever. Inlarger amounts, it may induce more serious problems, includ-ing liver damage, blindness, coma, convulsions, and death.One medical problem that has been associated with exposureto large amounts of naphthalene is hemolytic anemia, acondition in which red blood cells are destroyed, resultingin fatigue, restlessness, jaundice, loss of appetite, and, inmore serious cases, kidney failure.


‘‘Background and Environmental Exposures to Naphthalene,1 Methylnaphthalene, and 2 Methylnaphthalene in the UnitedStates.’’ Agency for Toxic Substances and Disease Registry.http://www.atsdr.cdc.gov/toxprofiles/tp67 c2.pdf (accessed onOctober 17, 2005).

Milius, Susan. ‘‘Termites Use Mothballs in Their Nests.’’ Science

News (May 2, 1998): 228.

‘‘Naphthalene Chemical Backgrounder.’’ National Safety Council.http://www.nsc.org/ehc/chemical/Naphthal.htm (accessed onOctober 17, 2005).

Words to Know

DISTILLATION A process of separating twoor more substances by boiling the mixtureof which they are composed and

condensing the vapors produced atdifferent temperatures.


NAPHTHALENE

OTHER NAMES:(S)-6-methoxy-

a-methyl-2-naphthaleneacetic

acid; d-2-(6-methoxy-2-naphthyl)-propionic

acid

FORMULA:C14H14O3


oxygen


(organic)

STATE:Solid





soluble in methylalcohol andchloroform

Naproxen

KE

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AC

TS

OVERVIEW

Naproxen (nah-PROK-sin) is a white to off-white odorlesscrystalline solid sold under a variety of commercial names,including Aleve�, Anaprox�, Bonyl�, Calosen�, Diocodal�,Naprosyn�, Naprelan�, Proxen�, and Veradol�. It is a non-steroidal anti-inflammatory drug (NSAID) used as an analge-sic (pain reliever) and antipyretic (fever-reducing compound).The compound is also available as a sodium salt, which ismore readily absorbed in the gastrointestinal tract. Nonster-oidal anti-inflammatory drugs are compounds used to reducepain, fever, and inflammation without the use of steroids(thus, nonsteroidal) by inhibiting the action of an enzymeneeded to produce these results in the body. Other examplesof NSAIDs are aspirin, ibuprofen, and prednisone.

HOW IT IS MADE

Naproxen is prepared by treating 2-methoxynaphtha-lene with a derivative of propanoic acid (CH3CH2COOH).

C C

C

O

C

C

CC

O

H

H

H

H H

H H

CHOC C

CH3

CH3

C C


2-methoxynaphthalene has a structure very similar to thatof naproxen and requires only the addition of the propa-noyl group (-CH2CH2COOH) provided by propanoic acid.The reaction is fairly straightforward but includes oneimportant consideration. Naproxen is a chiral compound,

Naproxen. Red atoms are oxygen; whiteatoms are hydrogen; and black atoms

are carbon. Striped sticks show benzenerings. P U B L I S H E R S R E S O U R C E G R O U P


NAPROXEN

meaning that it can exist in one of two isomeric forms. Thetwo forms are a ‘‘right-handed’’ form (designated as theR form) and a ‘‘left-handed’’ form (designated as the S form).As is the case with many organic compounds, the two chiralforms of naproxen have very different biological activities.Specifically, the S-form of naproxen is 28 times as effectiveas the R-form in achieving the analgesic, antipyretic, andanti-inflammatory results expected from the compound.Early methods for preparing naproxen resulted in the for-mation of a racemic mixture of R and S forms. A racemicmixture is one that contains both of the isomeric formsin which a compound can occur. The two parts of the racemicmixture, the R and S forms, then had to be separated fromeach other. Researchers have now developed a method ofmanufacture that produces essentially pure S naproxen,avoiding the time-consuming and costly process of separa-tion previously required.


Naproxen is commonly used to treat the pain and stiff-ness caused by conditions such as arthritis, inflammation ofthe joints, gout, tendonitis, and bursitis. It achieves thisresult by inhibiting the activity of an enzyme called cycloox-ygenase 2 (COX-2). COX-2 facilitates the production of a classof compounds in the body known as prostaglandins. Prosta-glandins are produced when the body is injured, causing thepain and inflammation usually associated with an injury.Naproxen blocks the active site on a COX-2 molecule thatcatalyzes the formation of COX-2 molecules with the result:no COX-2; no prostaglandins; no pain and inflammation. Inter-estingly enough, a very similar enzyme called cyclooxygenase

Interesting Facts

• The U.S. Food and DrugAdministration firstapproved the sale ofnaproxen as an over-

the-counter medication(one that does not requirea prescription) in 1994.


NAPROXEN

1 (COX-1) also exists in the body. COX-1, however, has adifferent set of functions that have nothing to do with theproduction of pain and inflammation. Since naproxen inhi-bits COX-2, but not COX-1, it is known as a selective inhibi-tor NSAID.

A number of relatively minor side effects have beenreported for naproxen, including headache, dizziness, drowsi-ness, itching, ringing in the ears, and minor gastrointestinaldiscomfort that may include heartburn, abdominal pain,nausea, constipation, and diarrhea. More serious problemshave also been reported, including gastrointestinal complica-tions such as bleeding and ulceration (bleeding sores) of thestomach and intestines. In some cases, the drug has beenresponsible for the hospitalization of users.

Care needs to be taken when combining naproxen withother medications. Known adverse drug interactions canoccur with aspirin, methotrexate, ACE inhibitors (for highblood pressure), furosemide, lithium, and warfarin (a bloodthinner). An overdose of naproxen may cause dizziness, drow-siness, and gastrointestinal problems. High blood pressure,kidney failure, and coma may occur, but are rare.


Buschmann, Helmut, et al. Analgesics: From Chemistry and Phar

macology to Clinical Application. New York: Wiley VCH, 2002.

‘‘Naproxen.’’ World of Molecules.http://www.worldofmolecules.com/drugs/naproxen.htm(accessed on October 17, 2005).

Words to Know


ISOMER One of two or more forms of achemical compound with the same

molecular formula, but different structuralformulas and different chemical andphysical properties.


NAPROXEN

Omudhome, Ogbru. ‘‘Naproxen Center.’’http://www.medicinenet.com/naproxen/article.htm (accessed onOctober 17, 2005).

‘‘Product Monograph: Anaprox�; Anaprox� DS.’’ Roche.http://www.rochecanada.com/pdf/Anaprox%20PM%20E.pdf(accessed on October 17, 2005).


NAPROXEN

OTHER NAMES:Nicotinic acid;

3-pyridinecarboxylicacid; vitamin B3

FORMULA:C6H5NO2


nitrogen, oxygen


(organic)

STATE:Solid




sublimes above itsmelting point


water, ethyl alcohol,and ether

Niacin

KE

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AC

TS

OVERVIEW

Niacin (NYE-uh-sin) is a B vitamin (vitamin B3) that isessential to cell metabolism. It occurs in two forms, nicotinicacid and nicotinamide, also called niacinamide. The onlystructural difference between the two compounds is that ahydroxyl group (-OH) in nicotinic acid is replaced by an aminogroup (-NH2) group in nicotinamide. Lack of niacin causesa disease called pellagra. Pellagra was common throughouthuman history among poor people whose diet consisted almostentirely of corn products. Those corn products did not supplyadequate amounts of niacin, causing symptoms such as diar-rhea, scaly skin sores, inflamed mucous membranes, weak-ness, irritability, and mental delusions. In some cases, peoplewith niacin deficiency develop reddish sores and rashes ontheir faces. Mental hospitals were full of people who seemedcrazy, but who were actually suffering from a dietary defi-ciency. Thousands of people died from pellagra every year.

Nicotinic acid was first isolated by the Polish-Americanbiochemist Casimir Funk (1884–1967) in 1912. At the time,

OH

C

CN

CH

HC

C OH

H

C


Funk was attempting to find a cure for another dietarydisease known as beriberi. Since nicotinic acid had no effecton beriberi, he abandoned his work with that compound. Itwas left, then, to the Austrian-American physician JosephGoldeberger (1874–1929) to find the connection betweennicotinic acid and deficiency diseases. In 1915, Goldbergerconducted a series of experiments with prisoners in a Mis-sissippi jail and found that he could produce pellagra byaltering their diets. He concluded that the disease was causedby the absence of some factor, which he called the P-P (forpellagra-preventative) factor. The chemical structure of thatfactor was then discovered in 1937 by the American bioche-mist Conrad Arnold Elvehjem (1901–1962), who cured thedisease in dogs by treating them with nicotinic acid.

HOW IT IS MADE

Niacin is synthesized naturally in the human body begin-ning with the amino acid tryptophan. Tryptophan occursnaturally in a number of foods, including dairy products,

Niacin. Red atoms are oxygen;white atoms are hydrogen;

black atoms are carbon; blueatom is introgen. Gray sticks



NIACIN

beef, poultry, barley, brown rice, fish, soybeans, and peanuts.People whose diet consists mainly of corn products do notingest adequate amounts of tryptophan, so their bodies areunable to make the niacin they need to avoid developingpellagra. It takes about 60 milligrams of tryptophan to pro-duce 1 mg of niacin.


Niacin plays a number of essential roles in the body. It isnecessary for cell respiration; metabolism of proteins, fats,and carbohydrates; the release of energy from foods; thesecretion of digestive enzymes; the synthesis of sex hor-mones; and the proper functioning of the nervous system.It is also involved in the production of serotonin, an essential

Interesting Facts

• Early investigators choseto use the name niacinrather than nicotinic acidbecause the later termsounds too much like‘‘nicotine.’’ They did notwant to give the impressionthat a person can getthe niacin they need bysmoking tobacco, whichcontains nicotine.

• Some good sources ofniacin include organ meats,such as kidney, liver, andheart; chicken; fish, such assalmon and tuna; milk anddairy products; brewer’syeast; dried beans andlegumes; nuts and seeds;broccoli and asparagus;whole grains; dates;mushrooms; tomatoes;

sweet potatoes; andavocados.

• Corn is also a good sourceof niacin. However, peoplewith corn-based diets areat risk for developingpellagra. The reason forthis contradiction is thatthe niacin in corn ischemically inactivated.Corn must be treated withan alkaline material toconvert the niacin itcontains to a free formthat the body can use.Native Americans whotreated their cornproducts with ley,limestone, wood ashes,or other alkaline materialsdid not suffer frompellagra.


NIACIN

neurotransmitter in the brain. Niacin deficiency disordersoccur as the result of an inadequate diet, consuming toomuch alcohol, and among people with certain types of cancerand kidney diseases. Physicians treat niacin deficiencydiseases by prescribing supplements of 300 to 1,000 milli-grams per day of the vitamin. Overdoses of niacin can cause avariety of symptoms, including itching, burning, flushing,and tingling of the skin.


Eades, Mary Dan. The Doctor’s Complete Guide to Vitamins and

Minerals. New York: Dell, 2000.

‘‘Niacin (Nicotinic Acid).’’ PDRHealth.http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/nia_0184.shtml (accessed on October 20, 2005).

‘‘Niacin Deficiency.’’ The Merck Manual.

http://www.merck.com/mrkshared/mmanual/section1/chapter3/3l.jsp (accessed on October 20, 2005).

‘‘Nicotinic Acid.’’ Gondar Design Science.http://www.purchon.com/biology/nicotinic.htm (accessed onOctober 20, 2005).

Words to Know

METABOLISM Process that includes all ofthe chemical reactions that occur in cellsby which fats, carbohydrates, and othercompounds are broken down to produceenergy and the compounds needed tobuild new cells and tissues.

MUCOUS MEMBRANES Tissues that linethe moist inner lining of the digestive,

respiratory, urinary, and reproductivesystems.

NEUROTRANSMITTER A chemical thatcarries nerve transmissions from onenerve cell to an adjacent nerve cell.

SUBLIME Change in state from a soliddirectly to a gas.


NIACIN

OTHER NAMES:r(S)-3-(1-methyl-2-pyr-

rolidinyl)pyridine;1-methyl-2-(3-pyridyl)-

pyrrolidine

FORMULA:C5H4NC4H7NCH3


nitrogen

COMPOUND TYPE:Alkaloid (organic)

STATE:Liquid




SOLUBILITY:Miscible with water;very soluble in ethyl

alcohol, ether, andchloroform

Nicotine

KE

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AC

TS

OVERVIEW

Nicotine (NIK-uh-teen) is a thick, colorless to yellow, oilyliquid with a bitter taste that turns brown when exposed toair. It occurs in high concentrations in the leaves of tobaccoplants and in lower concentrations in tomatoes, potatoes,eggplants, and green peppers. Nicotine gets its name fromthe tobacco plant, Nicotiana tabacum, which, in turn, wasnamed in honor of the French diplomat and scholar JeanNicot (1530–1600), who introduced the use of tobacco toParis. Nicotine’s correct chemical structure was determinedin 1843 by the Belgian chemist and physicist Louise Melsens(1814–1886) and the compound was first synthesized by theresearch team of A. Pictet and A. Rotschy in 1904.

HOW IT IS MADE

Nicotine is extracted by soaking the stems and leaves ofthe tobacco plant in water for about twelve hours. After thatperiod of time, the nicotine in the tobacco has dissolved in

N

CC

CH

HH

H

H

H

H

C

C

CC H

CC

N

CH3

H H


the water and can be extracted in a variety of ways. In oneprocess, the water solution of nicotine is mixed with ether orchloroform, in which the nicotine is more soluble. The nico-tine moves from the water layer to the ether or chloroformlayer, from which it can be removed by evaporation.


The best-known application of nicotine is in tobaccoproducts used for smoking and chewing. The actual nicotinecontent of tobacco products varies considerably, but, onaverage, ranges from about 15 to 25 milligrams per cigarette.Nicotine is also available in a number of products designed tohelp people stop smoking, such as nicotine gums and nico-tine patches.

Nicotine was often used by farmers and gardeners as aninsecticide and a fumigant in the past. Perhaps the best

Nicotine. White atoms arehydrogen; black atoms are

carbon; and blue atomsare nitrogen. P U B L I S H E R S



NICOTINE

known of these in the United States was an insecticideknown as Black Leaf 40, a 40 percent solution of nicotinesulfate in water. The use of Black Leaf 40 and most othernicotine-containing insecticides has, to a large extent, beendiscontinued because of the toxic nature of the compound.The risk it posed to human users was greater than its valueas an agricultural product.

Nicotine is a highly addictive substance. For that reason,people have difficulty stopping smoking or chewing tobaccoproducts even when they recognize the health hazards posedby the compound. Smokers depend on nicotine to give them aburst of energy, since it stimulates the heart rate and quick-ens blood flow. Once a person becomes addicted to the use ofnicotine, it requires larger doses of the compound to producecomparable effects. A 1998 U.S. government report issued bythen-Surgeon General C. Everett Koop found that the addic-tive properties of nicotine are comparable to those of heroinand cocaine.

When a person uses tobacco, nicotine is quickly absorbedthrough respiratory tissues, the skin, and the gastrointest-inal tract. The actual amount of nicotine absorbed by thebody depends on a number of factors, including the type oftobacco being smoked and the presence or absence of a filteron the cigarette. After entering the body, nicotine flowsthrough the bloodstream and across the blood brain barrier.Levels of the stimulating hormone adrenaline increase, as doblood sugar levels, respiration rates, blood pressure, andheart rate. Nicotine can make small arteries constrict, put-ting strain on the heart and raising blood pressure. If aperson already has clogged arteries, this effect may causeheart pain (angina) or a heart attack.

Interesting Facts

• It takes only about sevenseconds after nicotineis ingested before thechemical reaches thehuman brain.

• Nicotine is one of themost widely usedaddictive drugs in theUnited States.


NICOTINE

Although nicotine is a stimulant, it may induce musclerelaxation, depending on the user’s physical state. It has alsobeen shown to decrease one’s appetite, speed up metabolism,and increase levels of dopamine, a mood-altering chemicalin the brain that induces feelings of pleasure. Low levels ofdopamine play a role in the development of Parkinson’sdisease. Research has shown that smokers, with higher levelsof dopamine, have a reduced risk of the disease. Women whoare pregnant are advised not to use any product containingnicotine. Nicotine in any form is harmful to an unborn child.It rapidly crosses the placenta and enters the fetus’s body.

Nicotine is a highly toxic poison, which explains itsformer popularity as a pesticide. In high doses, it can belethal. Low doses of nicotine can cause dizziness, nausea,and vomiting. Symptoms of acute nicotine poisoning mayinclude a burning sensation in the mouth, more severe nau-sea and vomiting, diarrhea, heart palpitations, fluid in thelungs, seizures, coma, and death. People who smoke whilereceiving nicotine replacement therapy are at risk of nico-tine poisoning.


‘‘Acute Nicotine Poisoning.’’ Mosby’s Medical, Nursing, and Allied

Health Dictionary. 5th edition. St. Louis: Mosby, 1998.

‘‘Facts about Nicotine and Tobacco Products.’’ National Institute onDrug Abuse.http://www.drugabuse.gov/NIDA_Notes/NNVol13N3/tearoff.html(accessed on October 20, 2005).

‘‘Nicotine.’’ International Labour Organization.http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc05/icsc0519.htm (accessed onOctober 20, 2005).

Words to Know


NEUROTRANSMITTER A chemical thatcarries nerve transmissions from onenerve cell to an adjacent nerve cell.


NICOTINE

‘‘Nicotine (Black Leaf 40) Chemical Profile 4/85.’’ Pesticide Management Education Program, Cornell University.http://pmep.cce.cornell.edu/profiles/insect mite/mevinphos propargite/nicotine/insect prof nicotine.html(accessed on October 20, 2005).


NICOTINE

OTHER NAMES:Aqua fortis;

engraver’s acid;azotic acid

FORMULA:HNO3

ELEMENTS:Hydrogen, nitrogen,

oxygen


STATE:Liquid



BOILING POINT:83�C (180�F);decomposes

SOLUBILITY:Miscible with water;decomposes in ethyl

alcohol; reactsviolently with most

organic solvents

Nitric Acid

KE

YF

AC

TS

OVERVIEW

Nitric acid (NYE-trik AS-id) is a colorless to yellowish liquidwith a distinctive acrid (biting), suffocating, or choking odor.The acid tends to decompose when exposed to light, producingnitrogen dioxide (NO2), itself a brownish gas. The yellowishtinge often observed in nitric acid is caused by the presence ofsmall amounts of the nitrogen dioxide. Nitric acid is one ofthe strongest oxidizing agents known and attacks almost allmetals with the notable exceptions of gold and platinum.

Nitric acid has been known to scholars for many centu-ries. Probably the earliest description of its synthesis occursin the writings of the Arabic alchemist Abu Musa Jabir ibnHayyan (c. 721–c. 815), better known by his Latinized name ofGeber. The compound was widely used by the alchemists,although they knew nothing of its chemical composition. Itwas not until the middle of the seventeenth century that animproved method for making nitric acid was invented byGerman chemist Johann Rudolf Glauber (1604–1670). Glauberproduced the acid by adding concentrated sulfuric acid (H2SO4)

O OHN

O


to saltpeter (potassium nitrate; KNO3). A similar method isstill used for the laboratory preparation of nitric acid,although it has little or no commercial or industrial value.

The chemical nature and composition of nitric acid werefirst determined in 1784 by the English chemist and physicistHenry Cavendish (1731–1810). Cavendish applied an electricspark to moist air and found that a new compound—nitricacid—was formed. Cavendish was later able to determinethe acid’s chemical and physical properties and its chemicalcomposition. The method of preparation most commonly usedfor nitric acid today was one invented in 1901 by the Russian-born German chemist Friedrich Wilhelm Ostwald (1853–1932).The Ostwald process involves the oxidation of ammonia over acatalyst of platinum or a platinum-rhodium mixture.

Today, nitric acid is one of the most important chemicalcompounds used in industry. It ranks number thirteenamong all chemicals produced in the United States each year.In 2005, about 6.7 million metric tons (7.4 million short tons)of the compound were produced in the United States.

Nitric acid. Red atoms areoxygen; white atom is

hydrogen; and blue atom isnitrogen. Gray sticks indicate




NITRIC ACID

HOW IT IS MADE

Although several methods for the preparation of nitricacid are theoretically available, only one finds much commer-cial use: the direct oxidation of ammonia, an updated andimproved version of the traditional Ostwald process. In thismethod, ammonia is heated and reacted with air over acatalyst, most commonly a mixture of rhodium and platinummetals. That reaction results in the formation of nitric oxide(NO), which is then converted to nitrogen dioxide (NO2). Thenitrogen dioxide reacts with water to form nitric acid.


The most common use for nitric acid is in the manufacture ofammonium nitrate, which, in turn, is used primarily as a fertili-zer. About three-quarters of all nitric acid produced in the UnitedStates is used in fertilizers. The second most important applica-tion, accounting for about 10 percent of all nitric acid produced,is in the production of adipic acid [COOH(CH2)3COOH], used inthe manufacture of nylon, polyurethanes, and other syntheticplastics. Nitric acid is also used to make a variety of metalnitrates and for the cleaning of metals. Small amounts of thecompound are used for a variety of other applications, including:

• In the manufacture of explosives and fireworks;

• As a laboratory reagent in commercial, industrial, andacademic research laboratories;

• In the processing of nuclear fuels;

• For the etching of metals; and

• In the manufacture of certain types of dyes.

Interesting Facts

• Alchemists called nitricacid aqua fortis, a termthat means ‘‘strong water.’’

• Nitric acid is a componentof acid rain, a form of pol-

lution that results whensubstances such as nitro-gen oxides react with water,oxygen, and other chemi-cals in the atmosphere.


NITRIC ACID

Nitric acid is a highly toxic material. It attacks anddestroys skin and other tissues, leaving a distinctive yellowscar caused by the destruction of proteins in the skin ortissue. If swallowed, inhaled, or spilled on the skin, it cancause a number of effects, including severe corrosive burnsto the mouth, throat, and stomach; severe irritation or burn-ing of the upper respiratory system, including nose, mouth,and throat; damage to the lungs; severe breathing problems;and burns to the eye surface, conjunctivitis, and blindness.In the most severe cases, the acid can cause death.


‘‘Concentrated Nitric Acid (70%).’’ International Chemical SafetyCards.http://www.cdc.gov/niosh/ipcsneng/neng0183.html (accessedon October 20, 2005).

‘‘Material Safety Data Sheet.’’ Hill Brothers Chemical Company.http://hillbrothers.com/msds/pdf/nitric acid.pdf (accessed onOctober 20, 2005).

‘‘Nitric Acid.’’ Greener Industry.http://www.uyseg.org/greener_industry/pages/nitric_acid/1nitricAcidAP.htm (accessed on October 20, 2005).

‘‘Nitric Acid.’’ Scorecard. The Pollution Information Site.http://www.scorecard.org/chemical profiles/summary.tcl?edf_substance_id=7697%2d37%2d2 (accessed on October 20, 2005).

See Also Ammonia; Ammonium Nitrate; Nitrogen Dioxide;Nitroglycerin

Words to Know



MISCIBLE Able to be mixed; especially appliesto the mixing of one liquid with another.

OXIDATION A chemical reaction in whichoxygen reacts with some other substanceor, alternatively, in which some substanceloses electrons to another substance, theoxidizing agent.


NITRIC ACID

OTHER NAMES:Nitrogen monoxide

FORMULA:NO

ELEMENTS:Nitrogen, oxygen


(inorganic)

STATE:Gas





water

Nitric Oxide

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OVERVIEW

Nitric oxide (NYE-trik OK-side) is a sweet-smelling, color-less gas that can be liquefied to make a bluish liquid andfrozen to produce a bluish-white snow-like solid. It is one offive oxides of nitrogen, the others being nitrous oxide (N2O),nitric oxide (NO), dinitrogen trioxide N2O3), and nitrogendioxide (NO2). Nitric oxide was first discovered in 1620 byFlemish physician and alchemist Jan Baptista van Helmont(1580–1635 or 1644).

Nitric oxide is used in the production of nitric acid,ammonia, and other nitrogen-containing compounds. It isalso formed as a byproduct of the combustion of coal andpetroleum products. As such, it is a major contributor to airpollution.

HOW IT IS MADE

Nitrogen and oxygen are the two most abundant gases inthe atmosphere. Since both elements are relatively inactive,

N O


they do not combine with each other under normal circum-stances. However, the energy provided by lightning strikescauses the reaction of the two elements, producing nitric oxide.

N2 + O2 ! 2NO

Another source of the energy needed for this reaction isthe combustion of coal and oil products used for humanactivities. For example, the combustion of gasoline in aninternal combustion engine produces temperatures in excessof 2,000�C (3600�F). These temperatures are sufficient tobring about the reaction between nitrogen and oxygen in avehicle engine, resulting in the formation of nitric oxide asone product of gasoline combustion. That nitric oxide thenpasses into the atmosphere and becomes a major componentof air pollution.


The most important industrial use of nitric oxide is inthe preparation of other nitrogen-containing compounds,especially nitrogen dioxide (NO2), nitric acid (HNO3), andnitrosyl chloride (NOCl). It also finds some application inthe bleaching of rayon (a synthetic, or artificially created,fabric) and as a polymerization inhibitor with certain com-pounds such as propylene and methyl ether. Such compoundshave a tendency to react with each other to form large,complex molecules known as polymers.

Nitric oxide is considered an environmental pollutant. Itoxidizes readily to form nitrogen dioxide, which, in turn,

Nitrogen monoxide. Red atomis oxygen and blue atom is

nitrogen. P U B L I S H E R S



NITRIC OXIDE

reacts with moisture in the air to form nitric acid, a compo-nent of acid rain. Acid rain is thought to be responsible for anumber of environmental problems, including damage tobuildings, destruction of trees, and the death of aquatic life.The nitrogen dioxide produced from nitric oxide is also aprimary component of photochemical smog, a hazardoushaze created by a mixture of pollutants in the presence ofsunlight.

Even though it is toxic in the environment, nitric oxideplays several important roles in the human body. Nitric oxideis involved in the process by which messages are transmittedfrom one nerve cell to the next. It also regulates blood flowby triggering the smooth muscles surrounding blood vesselsto relax. This action increases blood flow and lowers bloodpressure. Nitric oxide also prevents the formation of bloodclots, which can break off and travel to the heart or brain,increasing the risk of heart attack or stroke.

During sexual arousal, nitric oxide increases blood flowto the penis, leading to an erection in a man. The drug Viagrastimulates erections by enhancing the flow of nitric oxide inthe penis.

Finally, nitric oxide plays a role in memory and learning.A deficiency of the compound appears to be related to thedevelopment of learning problems. On the other hand, anexcess of nitric oxide has been implicated in the develop-ment of certain diseases, such as Huntington’s chorea, aninherited disorder characterized by unusual body movements

Interesting Facts

• In 1992, Science magazinenamed nitric oxide‘‘Molecule of the Year’’after scientists discoveredthat it had several impor-tant functions in the body.

• Ferid Murad (1936– ),Robert Furchgott (1916– ),

and Louis Ignarro (1941– )shared the 1998 NobelPrize in Physiology orMedicine for theirdiscovery of the roleplayed by nitric oxide inthe body’s nervous system.


NITRIC OXIDE

and memory loss, and Alzheimer’s disease, a progressive dis-order that results in memory loss.

When used to treat a medical condition, nitric oxide isusually administered in the form of a solid or liquid medicinethat decomposes in the body, releasing the compound. Forexample, the drug nitroglycerin is used to treat heart pro-blems. When it enters the bloodstream, nitroglycerin beginsto break down, releasing nitric oxide. The nitric oxide causessmooth muscle cells in the heart to relax, relieving thesymptoms of angina, chest pain caused by an inadequateflow of blood to the heart. Other types of drugs produce nitricoxide to inhibit the buildup of fatty deposits in blood vessels,which can lead to heart attack and stroke. Patients withpulmonary hypertension, a condition in which the vesselsthat supply blood to the lungs are constricted, preventingnormal oxygen flow, are sometimes given an inhaler witha mixture of nitric oxide and air to open blood vessels tothe lungs.

In spite of its many benefits, nitric oxide may also be ahealth hazard. If inhaled in excessive amounts, it mayreplace oxygen in the lungs, leading to asphyxia, suffocationresulting from an insufficient supply of oxygen. Researchsuggests that exposure to low concentrations of the gas overlong periods of time may result in lung disease, emphysema,and chronic bronchitis.


Butler, A. R., and R. Nicholson. Life, Death and Nitric Oxide.

London: Royal Society of Chemistry, 2003.

‘‘Gas Data.’’ Air Liquide.http://www.airliquide.com/en/business/products/gases/gasdata/index.asp?GasID=44 (accessed on October 20, 2005).

Words to Know

POLYMERIZATION The process of creating apolymer, a compound consisting of very

large molecules made of one or two smallrepeated units called monomers.


NITRIC OXIDE

‘‘Nitric Oxide.’’ Reproductive and Cardiovascular Disease ResearchGroup.http://www.sgul.ac.uk/depts/immunology/~dash/no/ (accessedon October 20, 2005).

‘‘Nitrogen Oxides.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/ehc/ehc/ehc188.htm#SubSectionNumber:2.1.1 (accessed on October 20, 2005).

Stanley, Peter. ‘‘Nitric Oxide.’’ Biological Sciences Review (April2002): 18 20.

See Also Nitric Acid; Nitrogen Dioxide


NITRIC OXIDE

OTHER NAMES:Dinitrogen tetroxide;

nitrogen peroxide

FORMULA:NO2

ELEMENTS:Nitrogen, oxygen


(inorganic)

STATE:Gas or liquid


MELTING POINT:�11.2�C (11.8�F)


SOLUBILITY:Reacts with water to

form nitric acid(HNO3) and nitrous

acid (HNO2)

Nitrogen Dioxide

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OVERVIEW

Nitrogen dioxide (NYE-truh-jin dye-OK-side) is a toxicreddish-brown gas or yellowish-brown liquid with a pungent,irritating odor. Above 21.15�C (70.07�F), it exists as the red-dish-brown gas. Below that temperature, it becomes the yel-lowish-brown liquid. When liquified under pressure, it formsa fuming brown liquid. The brown liquid is actually a mixtureof nitrogen dioxide and dinitrogen tetroxide (N2O4), adimeric form of nitrogen dioxide. A dimer is a molecule thatconsists of two identical molecules combined with eachother. When cooled below �11.2�C (11.8�F), the liquid freezesto form a colorless crystalline solid that consists almostentirely of the dimeric form, N2O4.

Small amounts of nitrogen dioxide are present naturallyin the atmosphere as the result of lightning strikes, volcanicaction, forest fires, and bacterial action on dead plants andanimals. Much larger amounts are present because of humanactivities, primarily the combustion of fossil fuels, such ascoal and petroleum products.

ON

O

+

–


HOW IT IS MADE

Nitrogen dioxide occurs naturally when nitric oxide (NO)is oxidized in the atmosphere. Nitric oxide forms naturallywhenever sufficient energy is available to make possible thereaction between nitrogen and oxygen, the two primary com-ponents of the atmosphere. The formula for this reaction is

N2 + O2 ! 2NO

Nitric oxide, in turn, reacts readily with oxygen to formnitrogen dioxide. This reaction can be shown as

2NO + O2 ! 2NO2.

The amount of nitrogen dioxide produced naturally is sosmall that the gas’s distinctive brown color is unnoticeable.

Such is not the case, however, in situations where nitricoxide and nitrogen dioxide are produced by human activities.The burning of coal or oil in plants that generate electricityand the combustion of gasoline in automobiles and trucksproduce significant quantities of nitric oxide, which rapidlyoxidizes to form nitrogen dioxide in the atmosphere. In suchcases, sufficient nitrogen dioxide may be present to producethe yellowish hazy condition associated with smog.

Commercially, nitrogen dioxide is made by one of twoprocesses, the decomposition of nitric acid (HNO3) or the

Nitrogen dioxide. Red atomsare oxygen and blue atom is

nitrogen. Gray stick indicatesa double bond. P U B L I S H E R S



NITROGEN DIOXIDE

oxidation of ammonia (NH3) gas. The gas can also be producedon a smaller scale or in the laboratory by a number of methodsthat involve the decomposition of the nitrate ion (NO3). Forexample, heating lead(II) nitrate [Pb(NO3)2] results in the for-mation of lead(II) oxide (PbO), nitrogen dioxide, and oxygen.


The most important uses of nitrogen dioxide are in themanufacture of nitric and sulfuric acids, two of the mostwidely used inorganic acids. The compound is also used widelyas an oxidizing agent and nitrating agent. An oxidizing agentis a substance that makes oxygen available to other compoundsin order to bring about a particular reaction. A nitrating agentis one that provides the nitro group (-NO2) in producing a newcompound. As an example, adding nitrate groups to theorganic compound known as toluene (C6H5CH3) converts it intotrinitrotoluene (TNT), a powerful explosive. Nitrogen dioxideis also used in rockets, where it supplies the oxygen needed toburn the rocket fuel; as a catalyst in a number of industrialoperations; in the bleaching of flour; and as a polymerizationinhibitor in the manufacture of some plastics. A polymeriza-tion inhibitor is a substance that stops the formation of apolymer at some desired point in its production or use.

Nitrogen dioxide poses both safety and health hazards. Asa strong oxidizing agent, it reacts readily with combustiblematerials, such as paper, cloth, and other organic matter toproduce fires or explosions. It is also a toxic material, produ-cing some biological effects at relatively low concentrationsin the air. These effects include irritation of the eyes, nose,and throat; coughing; congestion; chest pain; and breathing

Interesting Facts

• Scientists often use theformula NOx to refer tothe oxides of nitrogen thatoccur in polluted air. Thetwo most important of

those oxides are nitricoxide (NO) and nitrogendioxide.


NITROGEN DIOXIDE

difficulties. The gas is sometimes referred to as an insidiousagent because its effects may go unnoticed for several hoursor days, during which time more serious damage may haveoccurred. This damage may include pulmonary edema, a condi-tion in which the lungs begin to fill with fluid; cyanosis, acondition in which the lips and mucous membranes turn bluebecause of lack of oxygen; and a variety of heart problems.Long-term exposure to nitrogen dioxide may result in chronichealth problems, such as hemorrhaging (blood loss), lungdamage, emphysema, chronic bronchitis, and eventually death.


‘‘Cheminfo: Chemical Profiles Created by CCOHS.’’http://www.intox.org/databank/documents/chemical/nitrodix/cie748.htm (accessed on October 20, 2005).

Holgate, S. T., et al. Air Pollution and Health. New York: AcademicPress, 1999.

‘‘NIOSH Pocket Guide to Chemical Hazards: Nitrogen Dioxide.’’Occupational Health & Safety Administration.http://www.cdc.gov/niosh/npg/npgd0454.html (accessed onOctober 20, 2005).

‘‘Nitrogen Oxides.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/ehc/ehc/ehc188.htm#SubSectionNumber:2.1.1 (accessed on October 20, 2005).

Patnaik, Pradyot. Handbook of Inorganic Chemicals. New York:McGraw Hill, 2003, 648 651.

See Also Nitric Acid

Words to Know

DIMER A molecule that consists of twoidentical molecules combined with eachother.


POLYMERIZATION INHIBITOR A substancethat stops the formation of a polymerat some desired point in its productionor use.


NITROGEN DIOXIDE

OTHER NAMES:Trinitroglycerol;trinitroglycerin;

glyceryl trinitrate

FORMULA:CH2NO2CHNOCH2NO2


nitrogen, oxygen


STATE:Liquid



BOILING POINT:Explodes at 218�C

424�F)


water; soluble inethyl alcohol,

acetone, and benzene

Nitroglycerin

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OVERVIEW

Nitroglycerin (nye-tro-GLIH-cer-in) is a pale yellow oilyflammable liquid that is highly explosive. It is used primarilyas an explosive by itself and as an ingredient in dynamite.Nitroglycerin also finds application in medicine as a vasodi-lator, a substance that causes blood vessels to relax and openup, allowing blood to flow more freely through them.

Nitroglycerin was first developed in 1847 by the Italianchemist Ascanio Sobrero (1812–1888). Sobrero used a methodof synthesis that is still the primary means of producingnitroglycerin today. He added nitric acid to glycerol, thenand now a popular skin lotion, with a small amount of con-centrated sulfuric acid as catalyst. He initially called hisdiscovery pyroglycerin. When he placed a trace amount ofnitroglycerin on his tongue, Sobrero discovered that it ‘‘givesrise to a most pulsating, violent headache, accompanied by agreat weakness of the limbs.’’ He also discovered that thechemical was highly combustible and explosive. He consid-ered the substance so dangerous that he warned against its

O O

O

O

O

N

N

O-

O- N

O

O

C

HH

H

CH

H

C


use and did not disclose his discovery to the world for morethan a year.

In the 1860s, the Swedish chemist Alfred Nobel (1833-1896) developed a process for manufacturing nitroglycerinon a large scale. His company sold a combination of nitro-glycerin and gunpowder called Swedish blasting oil, but theproduct proved far too dangerous to use. Several accidentsinvolving the substance occurred. One explosion in Nobel’sfactory killed several people, including his brother Emil.To make a safer explosive, Nobel found a way to combinenitroglycerin with clay, a chemically inactive material. Hecalled the combination dynamite. Dynamite soon became theexplosive of choice in construction, demolition, and miningprojects around the world.

Nitroglycerin’s medical uses were first explored in detailby Sir Thomas Lauder Brunton (1844–1916) of the RoyalInfirmary in Edinburgh, Scotland. In 1938, the U.S. Food

Nitroglycerin. Red atomsare oxygen; white atoms are

hydrogen; black atomsare carbon; and blue atoms arenitrogen. Gray sticks indicate




NITROGLYCERIN

and Drug Administration first approved the use of nitrogly-cerin as a vasodilator for the treatment of heart problems.

HOW IT IS MADE

The preparation of nitroglycerin is a straightforward,but very delicate, chemical procedure. When nitric acid isadded to glycerol, three nitrate groups (-NO2) replace each ofthe three hydroxyl (-OH) groups on glycerol. This reactionoccurs only if the acid and glycerol are moderately warm,at least at room temperature. But combining nitric acid,glycerol, and sulfuric acid (the catalyst) for the reactiongenerates heat. Too much heat causes the nitroglycerin beingproduced to explode. The resolution for this dilemma is tobegin the reaction at room temperature, but then encasethe reaction vessel in ice as soon as the reaction begins.The ice absorbs heat generated during the reaction, allowingthe formation of nitroglycerin without it becoming toowarm.

Interesting Facts

• Before Nobel beganstudying the explosiveproperties of nitroglycerin,people reportedly used thecompound for everydaychores, such as polishingboots and greasing wagonwheels, and even as lampoil. The consequences wereoften fatal.

• Although he spent mostof his life developing andmanufacturing explosives,Nobel was a humanitarianwho wanted to seetechnology used for thebenefit of society andthe advancement of world

peace. His handwrittenwill, although fiercelycontested, provided forthe creation of theNobel Foundation. Thefoundation’s primaryresponsibility is to awardprizes in chemistry,physics, physiology ormedicine, and peace everyyear. The first Nobel prizeswere awarded in 1901.Today, a Nobel prize isregarded as the highesthonor given in science.Each prize is worth overa million dollars in cash.


NITROGLYCERIN


Nitroglycerin’s primary use is as an explosive, either byitself or as a component of dynamite. Today, it is marketedunder more than 60 trade names, including Coro-Nitro�,Deponit�, GTN�, Nitroglin�, Nitrong�, Perglottal�,Reminitrol�, Sustac�, Tridil�, and Vasoglyn�. Nitroglycerinis classified as a high explosive, which means that itexplodes very rapidly with a very large force. It is detonated(‘‘set off’’) either by heat or by shock. Because of its veryunstable character, it is usually transported at low tempera-tures (5�C to 10�C; 40�F to 50�F), at which it is more stable.

When used as a heart medication, nitroglycerin is admi-nistered in the form of a pill, patch, or intravenous solution.Nitroglycerin works in the body by releasing nitric oxide, avasodilator. Vasodilators cause the smooth muscle surround-ing blood vessels to relax, allowing the vessels to expand andimprove the flow of blood. The drug is often taken when thepain of angina or a heart attack is first noticed.

People who come into contact with nitroglycerin in theworkplace are at risk for a number of health problems. Thecompound is a skin, eye, and respiratory system irritant.It may cause nausea, vomiting, abdominal cramps, headache,mental confusion, delirium, sweating, a burning sensation onthe tongue, paralysis, convulsions, and death.


‘‘Nitroglycerin.’ Imperial College of London, Department of Chemistry.http://www.ch.ic.ac.uk/rzepa/mim/environmental/html/nitroglyc_text.htm (accessed on October 20, 2005).

‘‘Nitroglycerin: Dynamite for the Heart.’’ Chemistry Review

(November 1999): 28.

Words to Know




NITROGLYCERIN

Rawls, Rebecca. ‘‘Nitroglycerin Explained.’’ Chemical & Engineer

ing News (June 10, 2002): 12.

‘‘Why Is Nitroglycerin Explosive?’’ General Chemistry Onlinehttp://antoine.frostburg.edu/chem/senese/101/consumer/faq/nitroglycerin.shtml (accessed on October 20, 2005).

See Also Nitric Acid; Sulfuric Acid


NITROGLYCERIN


FORMULA:N2O

ELEMENTS:Nitrogen; oxygen


(inorganic)

STATE:Gas





water; soluble inethyl alcohol and

ether

Nitrous Oxide

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OVERVIEW

Nitrous oxide (NYE-truss OX-side) is also known asdinitrogen oxide, dinitrogen monoxide, nitrogen monoxide,and laughing gas. It is a colorless, nonflammable gas with asweet odor. Its common name of laughing gas is derived fromthe fact that it produces a sense of light-headedness wheninhaled. The gas is widely used as an anesthetic, a substancethat reduces sensitivity to pain and discomfort.

Nitrous oxide was probably first produced by the Englishchemist and physicist Robert Boyle (1627–1691), although hedid not recognize the new compound he had found. Credit forthe discovery of nitrous oxide is, therefore, usually given tothe English chemist Joseph Priestley (1733–1804), who pro-duced the gas in 1772 and named it ‘‘nitrous air.’’ Other earlynames used for the gas include ‘‘gaseous of azote’’ (nitrogen)and ‘‘oxide of speton.’’ The most complete experiments on thegas were conducted by the English chemist and physicist SirHumphry Davy (1778–1829), who tested nitrous oxide onhimself and his friends. He found that the gas could lessen

O-N+

N


pain and discomfort and provided a sense of relaxation andwell-being. Before long, doctors were making use of Davy’sdiscovery by using nitrous oxide as an anesthetic.

The public found other uses for the gas as well. Duringthe Victorian period in England, members of the upper classoften held laughing gas parties at which people gathered toinhale nitrous oxide as a recreational drug, rather than forany therapeutic purpose. In the United States, the showmanP. T. Barnum (1810–1891) created a sideshow exhibit in whichpeople were invited to test the effects of inhaling nitrousoxide. After seeing a demonstration of this kind, the Ameri-can dentist Horace Wells (1815–1848) first used nitrous oxideas an anesthetic on his patients.

In 1868, the American surgeon Edmund Andrews (1824–1904) extended the use of nitrous oxide as an anesthetic forhis surgical patients. He mixed the gas with oxygen toensure that patients received enough oxygen while receivingthe anesthetic. The gas is still widely used by dentists as asafe and relatively pleasant way of helping patients endurethe discomfort of drilling and other dental procedures.

Nitrous oxide. Red atom isoxygen and blue atoms are

nitrogen. The nitrogen atomsshare a triple bond.



NITROUS OXIDE

HOW IT IS MADE

The most common commercial method of producingnitrous oxide involves the controlled heating of ammoniumnitrate (NH4NO3). The compound decomposes to form nitrousoxide and water. The reaction is essentially the same oneoriginally used by Priestley in 1772. Although an efficientmeans of producing the gas, the reaction must be carried outwith extreme care as ammonium nitrate has a tendency todecompose explosively when heated. Nitrous oxide can alsobe produced by the decomposition of nitrates (compoundscontaining the NO3 radical), nitrites (compounds containingthe NO2) radical, or nitriles (compounds containing the CH�

radical).


Nitrous oxide is best known and most widely used as ananesthetic. Its use is limited primarily to dental proceduresand minor surgeries. Dentists favor nitrous oxide as an anes-thetic because the gas does not make patients completelyunconscious and does not require an anesthesiologist toadminister it. Nitrous oxide works as an anesthetic by block-ing neurotransmitter receptors in the brain, preventing painmessages from being transmitted.

Nitrous oxide is also used as a fuel additive in racingcars, in which case it is often referred to as nitro. The gas isinjected into the intake manifold where it mixes with air andfuel vapors. Since it breaks down at the high temperatures inthe car’s engine, it provides additional oxygen to increase the

Interesting Facts

• Humphry Davy proposedthe name laughing gas fornitrous oxide.

• In the United Kingdom,nitrous oxide is often usedas an anesthetic forwomen about to give birth.

• In the 1830s, Samuel Colt(1814–1862), inventor ofthe Colt 45 revolver,toured North America,giving laughing gasdemonstrations.


NITROUS OXIDE

efficiency with which the fuel burns. During World War II,pilots used nitrous oxide for a similar purpose in their air-planes.

Some additional uses of nitrous oxide include:

• As a propellant in food aerosols;

• For the detection of leaks;

• As a packaging gas for potato chips and other snackfoods, preventing moisture from making the productbecome stale;

• In the preparation of other nitrogen compounds; and

• As an oxidizing agent for various industrial processes.

Nitrous oxide is safe to use in moderate amounts undercontrolled conditions. Some people use the compound as a

recreational drug, however, hoping to get a ‘‘high’’ from inhal-ing it. One risk of this practice is that the inhalation ofnitrous oxide may reduce the amount of oxygen a person

receives. Also, some long-term health effects, such as anemia(low red blood cell count) and neuropathy (damage to the

nerves), have been associated with excessive use of the com-pound. The use of nitrous oxide for recreational purposes is a

crime in some states.


‘‘Gas Data: Nitrous Oxide.’’ Air Liquide.http://www.airliquide.com/en/business/products/gases/gasdata/index.asp?GasID=55 (accessed on October 20, 2005).

Neff, Natalie. ‘No Laughing Matter.’’ Auto Week (May 19, 2003): 30.

Words to Know

ANESTHETIC A substance that reducessensitivity to pain and discomfort.

NITRATE A compound that includes theradical consisting of one nitrogen atomand three oxygen atoms (NO3).

NITRITE A compound that includes theradical consisting of one nitrogen atomand two oxygen atoms (NO2).

RADICAL A group of atoms bonded togetherthat act like a single entity in chemicalreactions.


NITROUS OXIDE

‘‘Nitrogen Oxide.’’ Center for Advanced Microstructures andDevices, Louisiana State University.http://www.camd.lsu.edu/msds/n/nitrous_oxide.htm#Synonyms(accessed on October 20, 2005).

‘‘Occupational Safety and Health Guideline for Nitrous Oxide.’’Occupational Safety and Health Administration.http://www.osha.gov/SLTC/healthguidelines/nitrousoxide/recognition.html (accessed on October 20, 2005).

Pae, Peter. ‘‘Sobering Side of Laughing Gas.’’ Washington Post

(September 16, 1994): B1.

See Also Ammonium Nitrate


NITROUS OXIDE

FORMULA:Nylon 6:

-[-CO(CH2)5NH-]-n;Nylon 66:

-[-CO(CH2)4

CO-NH(CH2)6NH-]-n


oxygen, nitrogen

COMPOUND TYPE:Polymer (organic)

STATE:Solid

MOLECULAR WEIGHT:Very large

MELTING POINT:Nylon 6: 223�C

(433�F); Nylon 66:265�C (509�C)


melting point


most organicsolvents; soluble in

strong acids

Nylon 6 and Nylon 66

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OVERVIEW

The term nylon is used to describe a family of organicpolymers called the polyamides that contain the amide (-CONH)group. The members of the family are distinguished from eachother by a numbering system indicating the chemical composi-tion of the polymer molecule. The two most important nylonsare nylon 6 and nylon 66 which, between them, account fornearly all of the nylon produced in the United States. Othernylons that are produced in much smaller amounts includenylon 11, nylon 12, nylon 46, and nylon 612.

The polyamides are thermoplastic polymers. The term‘‘thermoplastic’’ means that the polymer can be repeatedlymelted and hardened by alternate heating and cooling. Bycontrast, certain other types of polymers, known as thermo-setting plastics, can not be re-melted once they have har-dened.

Nylon was invented in 1935 by Wallace Carothers (1896–1937), an employee of the DuPont Chemical Corporation atthe time. Carothers was searching for a synthetic substitute

n

C

O

H

HH

H

H HH H

H H H

C C C C C N


of silk because natural supplies were insufficient to meet grow-ing demands for that fiber. Using coal, water, and air as rawmaterials, Carothers developed a synthetic product that could bestretched into a fiber and that got stronger and silkier as it wasstretched. Nylon first appeared in commercial products in 1938,first in toothbrushes with nylon bristles, and later in women’sstockings. During World War II, the U.S. military found a num-ber of uses for the compound, especially the manufacture ofparachutes. Today, nylon is used in a very wide array of products.

HOW IT IS MADE

Nylon 66 is still made commercially by the procedureoriginally developed by Carothers in 1935. The process isinitiated with the reaction between adipic acid (HOOC(CH2)4

COOH) and hexamethylenediamine (H2N(CH2)6NH2), whichresults in the formation of the monomer (-[-CO(CH2)4-

CONHCH2)6-]-) from which the polymer develops. That mono-mer has active groups at both ends of the molecule, allowingit to react with others of its kind to form long chains thatmake up the polymer. Methods for preparing the other poly-amides can differ quite significantly from the Carothersprocedure. For example, nylon 6 is made by the polymeriza-tion of aminocaproic acid (H2N(CH2)5COOH). The polymerformed in this reaction also has blocks of methylene (-CH2)groups joined by amide (CONH) groups, although the specificstructure is somewhat different than it is for nylon 66.


Production of nylon 6 and nylon 66 for 2006 in the UnitedStates was estimated to be about 1.6 million kilograms (3.5 mil-

Nylon 6. Red atom is oxygen;white atoms are hydrogen;

black atoms are carbon; blueatoms are nitrogen; gray stick

shows a single bond.P U B L I S H E R S R E S O U R C E G R O U P


NYLON 6 AND NYLON 66

lion pounds). About three-quarters of that production is used forthe manufacture of fibers used in industrial operations andfor textiles. Fabrics made from nylon are strong, resistant toabrasion, resistant to alkaline materials, and capable of takingmost dyes. The clothing industry uses nylon fibers to make avariety of fabric types, including fleece, velvet, satin, taffeta,lace, and seersucker. Nylon clothing is lightweight, silky,attractive and smooth. Since it does not absorb moisture orodors readily, it is in demand for the production of athleticclothing. Nylon is also used in the manufacture of home tex-tiles, such as furniture covering. Nylon rope is twice as strongas rope made from natural fibers such as hemp and weighs less.

About 15 to 20 percent of all nylon produced in theUnited States goes to the manufacture of molded plastics,such as those used in automobile and truck parts, housing forelectrical devices, and consumer articles. The next largestapplication for nylon is in tubing, pipes, films, and coatings.Some specific articles made from nylon 6 and nylon 66include the following:

• Reinforcing cord for tires;

• Fuel tanks for automobiles;

• Tennis rackets;

• Fishing nets and lines;

• Towlines for gliders;

• Women’s stockings;

• Sutures for surgical procedures;

Interesting Facts

• The term nylon has neverbeen trademarked. Thename itself has no specificmeaning. The -on suffixwas chosen, however, tosuggest a comparison withother fibers, such ascotton and rayon.

• DuPont originally thoughtof calling nylon No-Run.They abandoned that plan,however, when theyrealized that nylonstockings do, infact, run.



• Bristles for toothbrushes, hairbrushes, and paintbrushes;

• Parachutes;

• Pen tips; and

• Artificial turf for athletic fields.

One of the most important uses for nylon historically wasthe manufacture of women’s stockings. Silk stockings werean essential item of a well-dressed woman’s ensemble in the1920s and 1930s. They made a woman’s legs look smooth andsleek, and they were the ideal accompaniment to short skirtsand high heels. In the 1920s, women spent millions of dollarson silk stockings. The DuPont company began the search fora silk substitute because it hoped to develop a product thatcould be used to make stockings that looked and felt as ifthey were made of silk, but that cost less. Nylon stockingsbecame commercially available in 1939, and by 1941, somesixty million pairs had been sold. Both nylon and silk stock-ings were difficult to get during World War II because thefibers were being used for military applications. As soon asthe war was over, however, women began buying nylon stock-ings in large quantities once again.


Hermes, Matthew E. Enough for One Lifetime: Wallace Carothers,

Inventor of Nylon. Philadelphia: Chemical Heritage Foundation, 1996.

‘‘Nylons (Polyamides).’’ MatWeb.http://www.matweb.com/reference/nylon.asp (accessed onOctober 24, 2005).

Words to Know

POLYAMIDE An organic polymer thatcontains the amide (-CONH) group.


THERMOPLASTIC Capable of being heatedso that it can be reshaped, then cooledso that it hardens.

THERMOSETTING Capable of being heatedso that it hardens.



‘‘Nylon Stockings.’’ The Great Idea Finder.http://www.ideafinder.com/history/inventions/story062.htm(accessed on October 24, 2005).

‘‘Polyamide 6 Nylon 6 PA 6.’’ Azom.com.http://www.azom.com/details.asp?ArticleID=442 (accessedon October 24, 2005).

‘‘Polyamides.’’ Chemguide.http://www.chemguide.co.uk/organicprops/amides/polyamides.html (accessed on October 24, 2005).



OTHER NAMES:Ethanedioic acid

FORMULA:HOOCCOOH


oxygen

COMPOUND TYPE:Dicarboxylic acid;

organic acid (organic)

STATE:Solid


MELTING POINT:189.5�C (373.1�F);

begins to sublime at157�C (315�F)


SOLUBILITY:Soluble in water and

ethyl alcohol; slightlysoluble in ether;

insoluble in mostother organic

solvents

Oxalic Acid

KE

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AC

TS

OVERVIEW

Oxalic acid (ok-SAL-ik AS-id) is a transparent, colorless,crystalline solid that often occurs as the dihydrate (HOOC-COOH�2H2O). The dihydrate melts and begins to decomposeat 101.5�C (214.7�F), forming the anhydrous acid. The com-pound is odorless, but has a characteristic tart, acidic taste.The acid should never be tasted, however, as it is very toxic.

Oxalic acid is one of the first organic acids to have beendiscovered and studied. It was first isolated by the Germanchemist Johann Christian Wiegleb (1732–1800) in 1769 andfirst synthesized by the Swedish chemist Karl WilhelmScheele (1742–1786) in 1776. Friedrich Wohler’s (1800–1882)synthesis of oxalic acid entirely from inorganic materialswas a critical step in disproving the Vitalistic Theory ofchemistry. The theory claimed that compounds found in livingorganisms could be produced only by the act of some super-natural being, and not by human actions.

Oxalic acid occurs naturally in a number of vegetableproducts, including spinach, rhubarb, tea, chocolate, oats,

C

O O

C

OHHO


pumpkin, lentils, beets, parsnips, and many kinds of nuts andberries. The amount present in foods is generally so low thatit does not present risk to people who eat such products.

Oxalic acid also occurs as a product of carbohydrate meta-bolism in animals.

HOW IT IS MADE

Traditionally, oxalic acid has been extracted from naturalproducts by treating them with an alkaline solution, followedby crystallization of the acid. Sodium hydroxide is the alka-line material most commonly used for this procedure. Today,a number of methods are available for the commercial pre-paration of oxalic acid. In one procedure, carbon monoxidegas is bubbled through a concentrated solution of sodiumhydroxide to produce oxalic acid. Alternatively, sodiumformate (COONa) is heated in the presence of sodium hydro-xide or sodium carbonate to obtain the acid. Anotherpopular method of preparing oxalic acid involves the oxidationof sucrose (common table sugar) or more complex carbo-hydrates using nitric acid as a catalyst. The reaction resultsin the formation of oxalic acid and water as the primaryproducts.


Over a half million kilograms (about 1 million pounds) ofoxalic acid are produced in the United States each year.

Oxalic acid. Red atomsare oxygen; white atoms arehydrogen; and black atoms

are carbon. Gray sticks indicatedouble bonds. P U B L I S H E R S



OXALIC ACID

The greatest portion of the product is used in a variety ofcleaning products, including substances for the bleachingand cleaning of wood, cork, cane, feathers, and natural andsynthetic fibers. Many metal polishes, auto radiator cleaners,and laundry rinses also contain oxalic acid. Some rust-proofingmaterials also contain the compound.

The list of other household and industrial applications ofoxalic acid is extensive and includes:

• In the printing and dyeing of fabrics, especiallycalico;

• For the treatment of leather products, especially theleather used to make book covers;

• As a paint and varnish remover as well as a stainremover for ink and rust marks;

• In the manufacture of blue ink, celluloid, rubber, andother synthetic products;

• For the decolorization of glycerol and the stabilizationof hydrocyanic acid (HCN);

• As a purification agent for various chemicals, especiallymethanol (methyl alcohol); and

• In the preparation of certain medicines and pharmaceu-ticals.

Oxalic acid is a strong skin, eye, and respiratory irritantin pure form. It is also toxic by ingestion, causing nausea,vomiting, diarrhea, kidney damage, convulsions, coma, and

Interesting Facts

• One family of plants, theOxalidaceae, get theirname from the high con-centrations of oxalic acidthey contain. Perhaps thebest known member of thefamily is the wood sorrel.

• A number of moldsproduce oxalic acid as amajor metabolic product.Some species of Penicil-

lium and Aspergillus, forexample, convert glucoseinto oxalic acid.


OXALIC ACID

death. Since people are exposed to pure oxalic acid only inthe workplace, these hazards are usually not of concern tomost individuals. Of more concern to the general public isthe possibility of ingesting unusually large amounts of foodscontaining oxalic acid. In the body, the acid tends to reactwith calcium ions (Ca2+) forming calcium oxalate, which isinsoluble. This reaction has two harmful effects. First, itremoves calcium needed by the body for other biologicalfunctions, resulting in a calcium deficiency problem. Second,it may result in the precipitation of calcium oxalate crystalson the inner lining of blood vessels and the small tubesin the kidneys, reducing the flow of blood and resulting inthe development of kidney disorders.


‘‘Material Safety Data Sheet.’’ Hill Brothers Chemical Company.http://hillbrothers.com/msds/pdf/oxalic acid.pdf (accessed onOctober 23, 2005).

‘‘Oxalic Acid.’’ Al’s Home Improvement Center.http://alsnetbiz.com/homeimprovement/oxalic_acid.html(accessed on October 23, 2005).

Words to Know

ANHYDROUS COMPOUND A compound thatlacks any water of hydration.



METABOLISM Process that includes all ofthe chemical reactions that occur in cells


SUBLIME To go from solid to gaseous formwithout passing through a liquid phase.



OXALIC ACID

‘‘Oxalic Acid Dihydrate.’’ Chemical Land 21.http://www.chemicalland21.com/arokorhi/industrialchem/organic/OXALIC%20ACID.htm (accessed on October 23, 2005).

‘‘The Rhubarb Compendium.’’ Rhubarb Poison Information Center.http://www.rhubarbinfo.com/rhubarb poison.html (accessedon October 23, 2005).


OXALIC ACID


ELEMENTS:Carbon, hydrogen,oxygen, and other

elements


STATE:Solid

MOLECULAR WEIGHT:Varies widely: 20,000

to 400,000 g/mol




insoluble in organicsolvents

Pectin

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OVERVIEW

Pectin (PEK-tin) is a mixture, not a compound. Mixturesdiffer from compounds in a number of important ways. Theparts making up a mixture are not chemically combined witheach other, as they are in a compound. Also, mixtures haveno definite composition, but consist of varying amounts ofthe substances from which they are formed.

Chemically, pectin is a polysaccharide, a very large mole-cule made of many thousands of monosaccharide units joinedto each other in long, complex chains. Monosaccharides aresimple sugars. The most familiar monosaccharide is probablyglucose, the sugar from which the human body obtainsthe energy it needs to grow and stay healthy. The monosac-charides in pectin are different from and more complex thanglucose.

Pectin occurs naturally in many fruits and vegetables.It is most abundant in citrus fruits such as lemons, oranges,and grapefruits, which may consist of up to 30 percent pectin.In pure form it is a yellowish-white powder with virtually no

CO O

O

O

C

OH

OH

C

C CO O

O

C

OH

OH

C

CC

O

C

OH

OH

OH

C

C

C

C

O O

C

C

CH3

O O

C

CH3

C

n


odor and a slightly gummy taste. When dissolved in water, itforms a thick, jelly-like mass. This property explains one ofits primary purposes: the jelling of fruits when they are madeinto jams and jellies.

HOW IT IS MADE

Pectin is made naturally in ripening fruit. It is obtainedcommercially by treating the raw material (citrus peel orapple pomace) with hot, acidified water. (Apple pomace isthe residue remaining after pressing of apples.) The pectinin the peel or apple pomace dissolves in the hot water and isthen purified by repeated filtrations. It is extracted from thewater solution by adding alcohol or an aluminum salt to thesolution, causing the pectin to precipitate out of solution.The precipitate is then dried and ground into a powder.

Additional steps are sometimes carried out to convert thepectin produced by this method, called high ester pectin, to aform that is more soluble: low ester pectin. To achieve thischange, high ester pectin is treated with either acids oralkalis, washed, and purified.


Pectin is used primarily as a jelling agent in the manu-facture of jams and jellies. It also has a number of otherapplications as a food additive. For example, it is added tosome yogurts to provide the consistency that allows theyogurt to hold its shape and still be capable of being stirred.It is added to concentrated fruit drinks to keep the solid andliquid components of the drink in suspension with each other.It is also an ingredient in fruit and milk desserts, added toensure that the final product has the proper consistency andstability.

Pectin is also used as an additive in pharmaceutical andcosmetic preparations. It acts as an emulsifying agent, tostabilize the product, or to give it the proper consistency.In combination with an antibiotic, pectin has also been usedas an anti-diarrheal agent. Some studies have shown that dailydoses of pectin may have a small but significant loweringeffect on cholesterol levels.

The U.S. Food and Drug Administration has classifiedpectin as an approved food additive. It is considered safe


PECTIN

for human consumption when used in normal amounts as afood additive. It may cause some digestive problems forpeople with allergies to citrus fruits. Some studies suggestthat pectin may also inhibit the absorption of minerals suchas zinc, copper, iron, and calcium, although this effect is notserious enough to prevent its use as a food additive.

Interesting Facts

• The role of pectin in theformation of jams and jel-lies from fruits was firstrecognized in the 1820s.

• The first commercial man-ufacture of pectin tookplace in Germany in 1908.Producers of apple juicefound that they could useapple pomace, previouslya waste product, to makea useful product that couldbe sold, pectin.

• The first recipes for theuse of pectin to make jamsand jellies date to the firstcentury when the Romanwriter Marcus Gavius

Apicius wrote a recipe book‘‘Of Culinary Methods. ’;

• American inventor PaulWelch was granted apatent in 1917 for theproduction of grape jam,using pectin. Welch calledhis product Grapelade andsold his entire productionto the U.S. Army. The Armysent the Grapelade totroops serving in Europein World War I (1914–1918).After the war, returningtroops demanded moreGrapelade, making it apopular consumer itemin the United States.

Words to Know

EMULSION A temporary mixture of twoliquids that normally do not dissolve ineach other.

POLYSACCHARIDE A very large moleculemade of many thousands of simple sugarmolecules joined to each other in long,complex chains.

PECTIN



‘‘Genu� Pectin.’’ CP Kelco.http://www.cpkelco.com/food/pectin.html (accessed on December22, 2005).

Knox, J. Paul, and Graham B. Seymour, eds. Pectins and Their

Manipulation. Boca Raton, FL: CFC Press, June 2002.

‘‘Pectin.’’http://www.cfs.purdue.edu/class/f&n630/Virt_Class_2/pectin.htm (accessed on December 22, 2005).

‘‘Pectin.’’ PDRHealth.http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/pec_0198.shtml (accessed on December 22, 2005).

See Also Gelatin


PECTIN

OTHER NAMES:Not applicable; see

Overview

FORMULA:(CH3)2C5H3NSO

(COOH)NHCOR, whereR represents any one

of a number ofsubstituted groups;

see Overview


sulfur

COMPOUND TYPE:Bicyclic acid

(organic)

STATE:Solid

MOLECULAR WEIGHT:Varies; see Overview

g/mol

MELTING POINT:Varies; see Overview

BOILING POINT:Not applicable; allforms decompose

when heated abovetheir melting points



chloroform and mostorganic solvents

Penicillin

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OVERVIEW

The penicillins (pen-uh-SILL-ins) are a class of antibioticcompounds derived from the molds Penicillium notatum andPenicillium chrysogenum. The class contains a number ofcompounds with the same basic bicyclic structure to whichare attached different side chains. That basic structure con-sists of two amino acids, cysteine and valine, joined to eachother to make a bicyclic (‘‘two-ring’’) compound. The differentforms of penicillin are distinguished from each other byadding a single capital letter to their names. Thus: penicillinF, penicillin G, penicillin K, penicillin N, penicillin O, peni-cillin S, penicillin V, and penicillin X. A number of otherantibiotics, including ampicillin, amoxicillin, and methicil-lin, have similar chemical structures.

Penicillin was discovered accidentally in 1928 by theScottish bacteriologist Alexander Fleming (1881–1995). Flemingnoticed that a green mold, which he later identified asPenicillium notatum, had started to grow on a petri dish thathe had coated with bacteria. As the bacteria grew towards the

C C

C C

C

O

C HH C

N

H

H H

H

H

H

H

C N

C

HHS

CCH3

CCH3

OO C

OH

C

C


mold, they began to die. At first, Fleming saw some promisein this observation. Perhaps the mold could be used to killthe bacteria that cause human disease. His experimentsshowed, however, that the mold’s potency declined after ashort period of time He was also unable to isolate the anti-bacterial chemical produced by the mold. He decided thatfurther research on Penicillium was probably not worthwhile.

As a result, it was not until a decade later that Penicil-lium’s promise was realized. In 1935, English pathologistHoward Florey (1898–1968) and his biochemist colleagueErnst Chain (1906–1970) came across Fleming’s descriptionof his experiment and decided to see if they could isolate thechemical product produced by Penicillium with anti-bacterialaction. They were eventually successful, isolating and purifyinga compound with anti-bacterial action, and, in 1941, began trialswith human subjects to test its safety and efficacy (ability to killbacteria). The successful conclusion of those trials not onlyprovided one of the great breakthroughs in the human battleagainst infectious diseases, but also won for Florey, Chain, andFleming the 1945 Nobel prize for Physiology or Medicine.

HOW IT IS MADE

Penicillins are classified as biosynthetic or semi-synthetic. Biosynthetic penicillin is natural penicillin. It is

Penicillin. Red atoms areoxygen; white atoms arehydrogen; black atoms

are carbon; blue atoms arenitrogen; and yellow atom is

sulfur. Gray sticks show doublebonds; striped sticks indicate a

benzene ring. P U B L I S H E R S



PENICILLIN

produced by culturing molds in large vats and collecting andpurifying the penicillins they produce naturally. There aresix naturally occurring penicillins. The specific form of peni-cillin produced in a culturing vat depends on the nutrientsprovided to the molds. Of the six natural penicillins, onlypenicillin G (benzylpenicillin) is still used to any extent.

Semi-synthetic penicillins are produced by making che-mical alterations in the structure of a naturally occurringpenicillin. For example, penicillin V is made by replacing the-CH2C6H5 group in natural penicillin G with a -CH2OC6H5

group.


Penicillins are prescription medications used to treat avariety of bacterial infections, including meningitis, syphi-lis, sore throats, and ear aches. They do so by inactivating anenzyme used in the formation of bacterial cell walls. With theenzyme inactivated, bacteria can not make cell walls and dieoff. Penicillins do not act on viruses in the same way they doon bacteria, so they are not effective against viral diseases,such as the flu or the common cold.

A number of side effects are related to the use of peni-cillin. These side effects include diarrhea, upset stomach, andvaginal yeast infections. In those individuals who are allergic

Interesting Facts

• The discovery of penicillin’santibacterial action came atjust the right time: theonset of World War II. Thenew drug made possible thesaving of untold numbersof lives. As just one exam-ple, about three-quarters ofall soldiers who developedbone infections as a resultof wounds suffered in

World War I died of thoseinfections. By contrast, nomore than about 5 percentof those who developedsimilar infections in WorldWar II died. The availabilityof penicillin to treat thosewounds in World War IImade the difference inthose survival rates.


PENICILLIN

to penicillins, side effects are far more serious and includerash, hives, swelling of tissues, breathing problems, andanaphylactic shock, a life-threatening condition that requiresimmediate medical treatment.

Penicillin may alter the results of some medical tests,such as those for the presence of sugar in the urine. Penicil-lin can also interact with a number of other medications,including blood thinners, thyroid drugs, blood pressuredrugs, birth control pills, and other antibiotics, in some casesdecreasing their effectiveness.

Once promoted as wonder drugs, the use of penicillinshas declined slowly because of the spread of antibiotic resis-tance. Antibiotic resistance occurs when new strains of bac-teria evolve that are resistant to existing types of penicillin.One reason that antibiotic resistance has become a problemis the extensive and often unnecessary use of penicillins.When they are prescribed for colds and the flu, for example,they have no effect on the viruses that cause those diseases,but they encourage the growth of bacteria more able tosurvive against penicillins.


‘‘b Lactam Antibiotics: Penicillins.’’ The Merck Manual of Diagno

sis and Therapy. Chapter 153. Available online athttp://www.merck.com/mrkshared/mmanual/section13/chapter153/153b.jsp (accessed on October 23, 2005).

Chain, E. B. ‘‘The Chemical Structure of the Penicillins.’’ NobelLecture, March 20, 1945. Available online athttp://nobelprize.org/medicine/laureates/1945/chain lecture.pdf (accessed on October 23, 2005).

Words to Know

BICYCLIC Refers to a molecule in which theatoms are arranged so as to look like tworings.

BIOSYNTHETIC Natural; made from a livingorganism.

SEMI-SYNTHETIC Produced by makingchemical alterations in the structureof a naturally occurring organism.


PENICILLIN

Moore, Greogry A., and Ollie Nygren. ‘‘Penicillins.’’ The NordicExpert Group for Criteria Documentation of Health Risksfrom Chemicals.http://ebib.arbetslivsinstitutet.se/ah/2004/ah2004_06.pdf(accessed on October 23, 2005).

Ross Flanigan, Nancy. ‘‘Penicillins.’’ Gale Encyclopedia of Medicine.Edited by Jacqueline L. Longe and Deidre S. Blanchfield. 2nded. Detroit, MI: Gale, 2002.

‘‘Tom Volk’s Fungus of the Month for November 2003.’’http://botit.botany.wisc.edu/toms_fungi/nov2003.html(accessed on October 23, 2005).


PENICILLIN

OTHER NAMES:See Overview

FORMULA:–ClO4

ELEMENTS:Chlorine and oxygen,

in combination withother ions

COMPOUND TYPE:Inorganic salts

STATE:Solid


MELTING POINT:Ammonium perchlo-

rate: Decomposesexplosively when

heated; Potassiumperchlorate: 525�C

(977�F); Sodiumperchlorate: 480�C

(896�F)

BOILING POINT:Not applicable; all

decompose at orabove melting points


ammoniumperchlorate is also

soluble in methylalcohol and slightly

soluble in ethylalcohol

Perchlorates

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OVERVIEW

The perchlorates (per-KLOR-ates) are a family ofcompounds consisting of salts of perchloric acid, HClO4.

The family consists of dozens of compounds, the mostimportant of which are ammonium perchlorate (NH4ClO4),

potassium perchlorate (KClO4), and sodium perchlorate(NaClO4).

Although perchlorates have been known since the early

nineteenth century, they were not produced commerciallyuntil the 1890s. Even then, they were not produced in largevolumes until World War II (1939–1945), when they were

made for use in explosives. Perchlorate production contin-ued to grow in the post-war period, especially during the

military build-up that accompanied the Cold War (1945–1991) between the United States and the Soviet Union.

In recent years, however, concerns about the presence ofperchlorates in water supplies have become increasingly

widespread.

Cl

O

O

-O

O


HOW IT IS MADE

Each perchlorate is produced by a different method.Ammonium perchlorate, for example, is produced in a reac-tion among ammonium hydroxide (NH4OH), hydrochloricacid (HCl), and sodium chlorate (NaClO3).

Potassium perchlorate can be made in two ways. Onemethod by electrolyzing potassium chlorate (KClO3) in water.The other is by heating potassium chlorate (KClO3). Thisresults in a mixture of potassium perchlorate and potassiumchloride (KCl), which is removed.

Sodium perchlorate is made by heating a mixture ofsodium chlorate and sodium chloride. This reaction yieldssodium chloride (NaCl) as well as the sodium perchlorate.The excess sodium chloride is removed from the reaction,leaving sodium perchlorate behind.


By far the most important uses of perchlorates are in theproduction of explosives and fireworks and as jet and rocket

Perchlorate ion. Red atomsare oxygen. Green atom is

chlorine. P U B L I S H E R S



PERCHLORATES

fuels. These uses are based on the fact that all perchlorates arevery unstable oxidizing agents. An oxidizing agent is a mate-rial that supplies oxygen to some other substances or removeselectrons from that substance. When used in explosives, theperchlorates supply oxygen to the fuels in the explosive (suchas sulfur or carbon), causing them to burn very rapidly, pro-ducing large volumes of gases in a very short time. When usedas a rocket or jet fuel, perchlorates supply the oxygen neededto burn the fuel itself, such as kerosene or hydrogen.

Some perchlorates have other, more limited, uses. Forexample, potassium perchlorate was previously used to treatGraves disease, a condition in which the body produces toomuch thyroid hormone. It is still used to monitor the produc-tion of thyroid hormones. Potassium perchlorate is also usedin emergency breathing equipment for high altitude aircraftand underwater boats. Other uses of perchlorates include:

• In nuclear reactors and electronic tubes;

• As additives in lubricating oils;

• In the tanning and finishing of leather products;

Interesting Facts

• Small amounts of potas-sium perchlorate are foundnaturally in Chile indeposits of sodium nitrate.

• About 9 million kilograms(20 million pounds) ofperchlorates are producedeach year in the UnitedStates.

• In January 2005, the U.S.Environmental ProtectionAgency set a standardof 0.007 milligrams perkilogram of body weightas the maximum recom-mended dose a person

should ingest of perchlo-rates per day.

• Between 1997 and 2004,Lockheed Martin spent$80 million to study, cleanup, and replace local watersystems that had beencontaminated withperchlorates used by thecompany in the productionof military weapons androcket fuels. The twosystems were located nearRiverside and Redlands,California.


PERCHLORATES

• As a fixer for fabrics and dyes;

• In electroplating;

• In the refining of aluminum metal;

• In the manufacture of rubber products;

• In the production of certain paints and enamels.

Perchlorates pose a serious risk to humans because theyare unstable and have a tendency to explode spontaneously.They are also human health hazards, with harmful effects onboth the brain and the thyroid. They have a tendency toprevent the uptake of iodine by the thyroid, thus interferingwith the synthesis of hormones normally produced by thatorgan. Health officials believe that exposure to perchloratesmay cause infertility in women or may have harmful effectson their newborn children. These effects include mentalretardation and delays in their normal development. As aconsequence, efforts are underway to locate areas where per-chlorates may have entered the public water supply causingpotential health problems for people living in the region.


Perchlorate News.com.http://www.perchloratenews.com/index.html (accessed onDecember 10, 2005).

‘‘Perchlorates: New Report on Widespread Rocket Fuel Pollutionin Nation’s Food and Water.’’ Organic Consumers Association.http://www.organicconsumers.org/perchlorate.htm (accessedon December 10, 2005).

Words to Know

ELECTROLYSIS A process in which an elec-tric current is used to bring about chemi-cal changes.

SALT An ionic compound where the anion isderived from an acid.



PERCHLORATES

‘‘Potassium Perchlorate.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/P5983.htm(accessed on December 10, 2005).

‘‘Safety (MSDS) Data for Ammonium Perchlorate.’’ Physical andTheoretical Chemistry Lab.http://ptcl.chem.ox.ac.uk/MSDS/AM/ammonium_perchlorate.html (accessed on December 10, 2005).

Sharp, Renee, and Bill Walker. Rocket Science: Perchlorate and the

Toxic Legacy of the Cold War. Washington, D.C.: Environmental Working Group, July 2001. Also available online athttp://www.ewg.org/reports_content/rocketscience/perchlorate.pdf (accessed on December 10, 2005).

‘‘Toxicological Profile for Perchlorates.’’ Agency for Toxic Substances and Disease Registry.http://www.atsdr.cdc.gov/toxprofiles/tp162.html (accessed onDecember 10, 2005).


PERCHLORATES

OTHER NAMES:Petroleum jelly;

paraffin jelly;vasoliment; liquidparaffin; mineral

oil; paraffin oil




STATE:Semi-solid or liquid

MOLECULE WEIGHT:Not applicable



SOLUBILITY:Insoluble in water andethyl alcohol; soluble

in benzene,chloroform, ether,

carbon disulfide, andother organic

solvents

Petrolatum

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OVERVIEW

Petrolatum (peh-tro-LAY-tum) is a mixture, not a com-pound. Mixtures differ from compounds in a number ofimportant ways. The parts making up a mixture are notchemically combined with each other, as they are in a com-pound. Also, mixtures have no definite composition, butconsist of varying amounts of the substances from whichthey are formed.

Petrolatum is a complex mixture of hydrocarbonsderived from the distillation of petroleum. Hydrocarbonsare compounds that contain only carbon and hydrogen. Thehydrocarbons that make up petrolatum belong to themethane (saturated or alkane) family of hydrocarbons withthe general formula CnH2N+2. Some members of the familyinclude methane (CH4), ethane (C2H5), propane (C3H8), andbutane (C4H10).

Petrolatum occurs in a semi-solid or liquid form. Thesemi-solid form is also called petroleum jelly or mineral jellyand is commercially available under a number of trade


names, including Kremoline, Pureline, Sherolatum, andVaselineTM. It ranges in color from white to yellowish toamber. It is practically odorless and tasteless. It melts over awide range, from about 38�C to about 55�C (100�F to 131�F).The liquid form is also known as liquid paraffin, mineraloil, or white mineral oil. Such products are sold commer-cially under trade names such as Alboline, Drakeol, Frigol,Kremol, and Paroleine. It is a colorless, tasteless, and odor-less oily liquid.

Oil was first discovered in the United States in the 1850sin western Pennsylvania. A chemist from Brooklyn, NewYork, Robert Augustus Chesebrough (1837–1938), visitedthe new wells and noticed a wax-like material stickingto the petroleum drilling rods. He learned that oil workersused the ‘‘rod wax’’ to heal burns on their skin. Chesebrougheventually extracted and purified the substance—petrolatum—from petroleum and began manufacturing it in 1870. Hereceived several patents for his discovery and in 1878, hegave his product the trade name of VaselineTM. His productquickly became popular as an ointment for wounds andburns. Unlike the animal and vegetable oils then being usedfor that purpose, petrolatum did not spoil. By the late 1870s,VaselineTM was selling at the rate of one jar every minute inthe United States. In 1880, it was added to the U.S. Pharma-copoeia, a manual that lists drugs used in medical practice.

HOW IT IS MADE

Petrolatum is a product of the fractional distillation ofcrude oil. Crude oil is a complex mixture of hundreds orthousands of compounds. These compounds can be separated,or distilled, from each other by heating crude oil to hightemperatures. As the temperature of the crude oil rises,various groups or a ‘‘fraction’’ of compounds boil off. The firstgroup of compounds includes gaseous compounds dissolvedin crude oil. The next group of compounds includes com-pounds with low boiling points. The next group of com-pounds includes compounds with slightly higher boilingpoints. And so on. Eventually, a tar-like mass of compoundswith very high boiling points is left behind in the distillingtower. This residue is heated to separate liquids from solidsremaining behind. Some of these liquids and solids make upthe semi-solid and liquid forms of petrolatum.


PETROLATUM


Petrolatum has a wide variety of uses, ranging frompersonal care and medical applications to industrial uses.The solid form, such as VaselineTM is used as a topical oint-ment for the treatment of dry, cracked skin and to reduce therisk of infection. It works as a moisturizing agent because itreduces water loss from the skin, It helps prevent infectionbecause it creates a barrier over wounds that prevents dis-ease-causing organisms from entering the body. Solid petro-latum is also an ingredient in many skin care and cosmeticproducts, such as skin lotions, body and facial cleansers, anti-perspirants, lipsticks, lip balms, sunscreens, and after-sunlotions. In hair products, it helps smooth frizzy hair byallowing hair to retain its natural moisture. The formationused in most of these products remains virtually unchangedfrom that developed by Robert Chesebrough in the 1800s.

Solid petrolatum is also used in industrial applicationsfor a variety of purposes, such as:

• As a softener in the production of rubber products;

• In the food processing industry, to coat raw fruits andvegetables and to help products retain moisture;

• As a defoaming agent in the production of beet sugarand yeasts;

• For the lubrication of firearms and machine parts;

Interesting Facts

• Both solid and liquidpetrolatum are availablein three grades, known asUSP (U.S. Pharmacopoeia),NF (National Formulary),and FCC (Food ChemicalsCodex).

• A synthetic version ofpetrolatum is made fromsoybean oil as an alterna-

tive to petroleum-basedpetrolatum. It is usedprimarily in the manu-facture of cosmetics.

• Skin care products gener-ally contain petrolatum ina concentration of about1 to 3 percent.


PETROLATUM

• In the production of modeling clays;

• In the manufacture of candles, to prevent a candle fromshrinking as it cools after being burned;

• In the preparation of shoe polishes; and

• As an ingredient in rust preventatives.

The primary use of liquid petrolatum is as a laxative, aproduct that loosens the bowels. It also has a number of otherapplications, such as an additive in foods such as candies,confectionary products, and baked goods; as an ingredient inpersonal care products, such as baby oil creams, hair condi-tioning lotions, and ointments; in many different kinds ofpharmaceutical preparations; in the production of industriallubricants; as a softening agent in the manufacture of rub-ber, textiles, fibers, adhesives, and machine parts; as dustsuppressants; and as dehydrating agents for a number ofindustrial processes.


‘‘Another Old Fashioned Product Vindicates Itself.’’ Medical Update

(October 1992): 6.

Morrison, David S. ‘‘Petrolatum: A Useful Classic.’’ Cosmetics and

Toiletries (January 1996): 59 68. Also available online athttp://www.penreco.com/newsevents/tradearticles/petrolatumclassic.pdf (accessed on December 22, 2005).

‘‘Material Safety Data Sheet.’’ Penreco.http://www.penreco.com/products/pdfs/petrolatum/pen00421technicalpetrolatum.pdf (accessed on December 22,2005).

Words to Know

FRACTIONAL DISTILLATION The processof extracting compounds from petroleumby heating the petroleum and collectingthe individual compounds as they boiloff when their boiling points arereached.

HYDROCARBON A compound that containshydrogen and carbon atoms.



PETROLATUM

Penreco (Petrolatum company).http://www.penreco.com/index.asp (accessed on December 22,2005).

Schramm, Daniel. ‘‘The North American USP Petrolatum Industry.’’ Soap & Cosmetics (January 2002): 60 63.

See Also Petroleum


PETROLATUM

OTHER NAMES:Crude oil; oil



oxygen, otherelements


STATE:Liquid

MOLECULAR WEIGHT:Not applicable



SOLUBILITY:Not miscible with

water; miscible withmost organic solvents

Petroleum

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OVERVIEW

Petroleum (peh-TRO-lee-yum) is a mixture, not a com-pound. Mixtures differ from compounds in a number ofimportant ways. The parts that make up a mixture are notchemically combined with each other, as they are in a com-pound. Also, mixtures have no definite composition, butconsist of varying amounts of the substances of which theyare formed.

Petroleum is a very complex mixture of hydrocarbons—compounds that consist of carbon and hydrogen only. Smallamounts of other organic compounds containing oxygen,sulfur, nitrogen, phosphorus, and other elements are alsopresent. The hydrocarbons that make up petroleum includethe alkanes, alkenes, alkynes, cyclic hydrocarbons, and aro-matic hydrocarbons. Alkanes are hydrocarbons in which carbonand hydrogen are bonded to each other by single bonds. Inalkenes, at least one double bond is present. In alkynes,carbon and hydrogen atoms are bonded by at least one triplebond. In cyclic hydrocarbons, the carbon atoms are arranged


in a ring. In aromatic hydrocarbons, the carbon atoms arejoined to each other in a ring that has alternate single anddouble bonds. Many of the hydrocarbons in petroleum alsohave side chains that also consist of carbon and hydrogenatoms.

The physical properties of petroleum vary somewhat,depending on the source from which it comes and its compo-sition. Generally, it is a thick, oily liquid that is dark yellowto brown to greenish-black in color, with a strong, unpleasantodor.

HOW IT IS MADE

Scientists believe that petroleum was formed about 300million years ago. When microscopic plants and animals thatlived in the ocean died and sank to the bottom, they weregradually covered and compressed with more layers oforganic material along with sand and mud. As the mud grewthicker, it created pressure on the organic material, causingit to become increasingly warmer. The heat and pressurecaused the organic matter to decay in the absence of oxygen,converting it into petroleum and natural gas.

Over time, the primitive oceans dried up. The sand andmud that had accumulated on the ocean floors changed intorock. The natural gas and liquid petroleum that had formedon the ocean floor was trapped in the rock. It flowed throughcracks in the rock until it reached porous rock that acted likea sponge and soaked up the petroleum and natural gas. Thesefossil fuels remain trapped in the porous rock by non-porouslayers of rock that act like caps or seals on the porous rocks.

Geologists have discovered a number of ways of findingthese oil- and gas-soaked reservoirs. They measure changes inthe Earth’s magnetic field and use electronic ‘‘sniffers’’ thatcan detect hydrocarbons trapped in rock. Once oil is found,prospectors extract it by drilling into the porous rock. Thepressure of gases within the porous rock pushes petroleumup to the surface, where it can be captured and stored.

Liquid petroleum has no commercial value as it comesfrom the earth. After it is captured from wells, therefore, ithas to be refined, or separated into useful components. Refiningis a process by which petroleum is heated to high temperaturesin a tall cylindrical tower. The many different hydrocarbons


PETROLEUM

in petroleum boil off and rise upward in the tower. Thehigher they rise, the more they cool off.

Each hydrocarbon eventually reaches a height at which itchanges back to a liquid. Traps are inserted at variousheights in the tower to catch each hydrocarbon as it changesback to a liquid. One level of traps, for example, catcheshydrocarbons that condense to a liquid between about 40�Cand 170�C (100�F and 340�F). This ‘‘fraction’’ is called thegasoline or petrol fraction of petroleum. Another level oftraps catches hydrocarbons that condense between tempera-tures of about 170�C and 250�C (340�F and 480�F). Thisgroup of hydrocarbons is called the kerosene fraction. Theother major fractions obtained from petroleum are the dieseland fuel oil fractions. Anything that boils above about 400�C(750�F) is referred to as the residual oil fraction. In manycases, each of the fractions obtained by this process can befurther refined to separate it into even smaller fractions.


By far the most common use of petroleum is as gasolinefor automobiles and trucks. About 90 percent of the petro-leum used in the United States fuels vehicles powered byinternal combustion engines. Diesel fuel is used to powertrucks, buses, trains, and some automobiles. Heating oilwarms buildings and powers industrial boilers. Utilities useresidual fuel oil to generate electricity. Jet fuel, producedfrom kerosene, powers airplanes. Some airplanes use aviation

Interesting Facts

• The United States uses byfar more petroleum thanany other nation in theworld. It uses about 1,000billion liters (250 billiongallons) every year.About half that amountis imported from other

countries, primarily inthe Middle East.

• The average fuel economyof automobiles producedin the United States hasdecreased steadily since1985.


PETROLEUM

gasoline, which has a higher octane number than automobilegasoline. Octane number is a measure of a fuel’s efficiency.

Kerosene is used to power lamps and heaters. Powerplants and factories use petroleum coke, a solid fuel madeof petroleum, as a fuel. Asphalt and tar, solid materials leftover after the fractionation of petroleum, are componentsof paved roads. Petrolatum, another solid component of pet-roleum, is used as a lubricant and moisturizer. Paraffin wax,also obtained as a by-product of petroleum distillation, is aningredient in candles, candy, polishes, and matches. Otherforms of petroleum are used as lubricating oils for engines oras solvents in paints.

A second very important use of petroleum is in the manu-facture of plastics and other chemicals. The number of chemi-cal compounds obtained from petroleum and used as rawmaterials in chemical reactions is almost endless. It includescompounds such as methane, ethane, propane, butane, ethene(ethylene), propene (propylene), butene (butylene), benzene,methanol (methyl alcohol), ethanol (ethyl alcohol), phenol,xylene, naphthalene, and anthracene, to mention only a few.

There are many drawbacks associated with using petro-leum as a fuel. One of the most important is environmentalpollution. Burning petroleum products releases greenhousegases—gases that tend to accumulate in the atmosphere andcontribute to a gradual warming of the Earth’s annual aver-age temperature. Other pollutants produced when petroleumproducts are burned include sulfur oxides and oxides ofnitrogen, compounds that contribute to the development ofacid rain, and carbon monoxide and ozone, pollutants thatdamage plant and animal life as well as physical structures,like buildings and statues.

The production and transportation of petroleum productsalso poses environmental problems. Oil spills that occur dur-ing any phase of petroleum production and use may killaquatic life and pollute an area for years. The worst oil spillin North America, for example, occurred during the wreck ofthe oil tanker Exxon Valdez in 1989, when 40,000 tons ofcrude oil were dumped into Alaska’s Prince William Sound.The worst oil spill in the world occurred in 1978 as a result ofthe wreck of the oil tanker Amoco Cadiz off the coast ofBrittany, France. More than 220,000 tons of oil were releasedduring that accident.


PETROLEUM


American Petroleum Institute.http://api ec.api.org/newsplashpage/index.cfm (accessed onDecember 22, 2005).

Hyne, Norman J. Nontechnical Guide to Petroleum Geology,

Exploration, Drilling and Production, 2nd ed. Tulsa, OK: Pennwell Books, 2001.

Leffler, William L. Petroleum Refining in Nontechnical Language.

Tulsa, OK: Pennwell Books, 2000.

‘‘Oil and Gas Energy for the World.’’ Institute of Petroleum.http://www.energyinst.org.uk/education/oilandgas/energy.htm(accessed on December 22, 2005).

‘‘Petroleum.’’ U.S. Energy Information Administration.http://www.eia.doe.gov/oil_gas/petroleum/info_glance/petroleum.html (accessed on December 22, 2005).

‘‘Petroleum Refining Processes.’’ OSHA Technical Manual.Washington, DC: Occupational Safety and Health Administration, 1999.. Available online athttp://www.osha.gov/dts/osta/otm/otm_iv/otm_iv_2.html#1(accessed on December 22, 2005).

See Also Methane; Petrolatum; Propane

Words to Know


HYDROCARBON A compound that containshydrogen and carbon atoms.




PETROLEUM

OTHER NAMES:Hydroxybenzene;

carbolic acid; phenylicacid; benzophenol;

phenic acid

FORMULA:C6H5OH


oxygen

COMPOUND TYPE:Aromatic alcohol

(organic)

STATE:Solid





ethyl alcohol, ether,chloroform, acetone,

benzene, and otherorganic solvents

Phenol

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OVERVIEW

Phenol (FEE-nol) is a white, crystalline solid with a char-acteristic odor and a sharp, burning taste. It tends to turnpink or pale red when exposed to light if not perfectly pure.Phenol has a tendency to absorb moisture from the air,changing into an aqueous solution of the compound. Suchsolutions have a slightly sweet flavor.

Phenol was probably first observed by German chemistJohann Rudolf Glauber (1604–1668). Glauber obtained phenolby condensing coal tar vapors and separating them intoindividual compounds. Coal tar is a thick black liquid leftover when coal is heated in the absence of air to make coke.Phenol was largely ignored for almost 200 years untilanother German chemist, Friedlieb Ferdinand Runge (1795–1867), isolated phenol in 1834, also from coal tar. Runge gavethe name carbolic acid to his discovery, a name that is stillused occasionally for the compound. In 1843, French chemistCharles Frederic Gerhardt (1816–1856) suggested the modernname of phenol for the compound.

CCC

CCC

H

H

HH

OHH


The term phenol is also used to describe a class of aro-matic organic compounds. Such compounds have a six-carbonring structure like that of benzene (C6H6) to which isattached one or more hydroxyl (-OH) groups. Benzene is thesimplest member of this group. Other members include thecresols (CH3C6H4OH), xylenols ((CH3)2C6H3OH), and the resor-cinols (C6H4(OH)2). The production of phenol amounts toabout 6 million metric tons (about 6.5 million short tons)annually in the United States. The largest single use of phenol

Phenol. Black atoms arecarbon; red atom is oxygen;white atoms are hydrogen.

Bonds in the benzene ring arerepresented by the double

striped sticks. White sticksshow single bonds. P U B L I S H E R S



PHENOL

is in the production of bisphenol A ((CH3)2C(C6H4OH)2) and avariety of plastics, primarily formaldehyde resins.

HOW IT IS MADE

In the early twenty-first century, virtually all of thephenol made is produced from cumene (C6H5CH(CH3)2).Cumene is first oxidized to produce cumene hydroperoxide:C6H5CH(CH3)2 + O2 ! C6H5(COOH)(CH3)2. The cumene hydro-peroxide is then treated with concentrated sulfuric acid(H2SO4) to obtain a mixture of acetone (CH3COCH3) and phe-nol: C6H5(COOH)(CH3)2 + H2SO4 ! CH3COCH3 + C6H5OH.

Interesting Facts

• The only source of phenoluntil World War I (1914–1918) was coal tar.

• German chemist FriedrichRaschig (1863-1928) devel-oped the first syntheticmethod for making phenolin 1915. The processinvolves the hydrolysis ofchlorobenzene (C6H5Cl).

• Demand for phenolincreased significantly in1909 when German chemistLeo Hendrik Baekeland(1863–1944) announcedthe discovery of a newsynthetic material, Bake-lite, made from phenol andformaldehyde (CH2O).Bakelite was the firstthermosetting plasticever discovered. A thermo-setting plastic is one that,once shaped into some

form, cannot be remeltedagain.

• The use of carbolic acid asan antiseptic was firstsuggested by Sir JosephLister (1827–1912) in 1865.Lister found that sterili-zing medical instrumentsand treating wounds withcarbolic acid dramaticallyreduced the number ofdeaths resulting frompost-operative infections.

• The effectiveness ofa substance in preventingbacterial infection is stillexpressed by a measureknown as the phenol

coefficient, theeffectiveness of thematerial compared tothat of a comparableamount of phenol.


PHENOL


The primary use for phenol is as an intermediarychemical, a compound used in the synthesis of other che-micals. About 40 percent of all the phenol produced in theUnited States is used to make bisphenol A, while a similaramount is used in the production of a variety of polymers,such as phenol-formaldehyde plastics and nylon-6. Thethird largest application of phenol is in the manufactureof a host of other chemicals, xylene and aniline being themost important.

Phenol is no longer widely used as an antiseptic, partlybecause more efficient substances have been developed andpartly because phenol may cause irritation and burning ofthe skin after prolonged use. The compound is still used inlow concentrations in a number of health and medical appli-cations, however, as in antipruritics (substances that reduceor prevent itching), cauterizing agents (substances for theburning of tissue by heat or chemicals), topical anesthetics(anesthetics used on the skin), chemexfoliants (substancesthat remove skin), throat sprays and lozenges (such asChloraseptic�, Ambesol�, and Cepastat�), and in skin oint-ments (such as PRID salve� and CamphoPhenique� lotion).Phenol is also used in combination with slaked lime (calciumhydroxide; Ca(OH)2) and other materials as a disinfectantfor toilets, stables, cesspools, floors, and drains.

Phenol is a highly corrosive material that can causeserious burns to the skin, eyes, and respiratory system. It istoxic if ingested. The compound can enter the body in avariety of ways, such as absorption through the skin, inhala-tion of vapors, and ingestion of the solid compound or itssolutions. Symptoms of phenol poisoning include nausea,vomiting, headache, respiratory failure, muscular weakness,severe depression, collapse, coma, and death. Skin exposuremay cause redness, blisters, and/or minor to severe chemicalburns. Ingestion of phenol may cause damage to the centralnervous system, lungs, kidneys, liver, pancreas, and spleen.The concentration of phenol in most consumer and industrialproducts is low enough not to cause health problems forusers. However, prolonged exposure to such products or theiroveruse may result in serious health risks. Handling of thepure compound or concentrated solutions of phenol alsoinvolves health hazards.


PHENOL


‘‘Occupational Safety and Health Guideline for Phenol.’’ Occupational Safety and Health Administration.http://www.osha.gov/SLTC/healthguidelines/phenol/recognition.html (accessed on December 29, 2005).

‘‘Phenol.’’ Greener Industry.http://www.uyseg.org/greener_industry/pages/phenol/1PhenolAnnualProd.htm (accessed on December 29, 2005).

‘‘Phenol.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/pims/chemical/pim412.htm (accessed on December 29, 2005).

‘‘ToxFAQsTM for Phenol.’’ Agency for Toxic Substances and DiseaseRegistry.http://www.atsdr.cdc.gov/tfacts115.html (accessed on December29, 2005).

Tyman, J. H. P. Synthetic and Natural Phenols. Amsterdam: Elsevier,1996.

See Also Cumene; Polyamide 6,6

Words to Know






PHENOL

OTHER NAMES:Orthophosphoric acid

FORMULA:H3PO4

ELEMENTS:Hydrogen, phos-phorus, oxygen


STATE:Solid. See Overview


MELTING POINT:42.4�C (108�F)


SOLUBILITY:Very soluble in water

and ethyl alcohol

Phosphoric Acid

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OVERVIEW

Phosphoric acid (fos-FOR-ik AS-id) melts at a temperaturejust above room temperature (about 20�C; 68�F), so wouldbe expected to occur as a solid under those conditions. As asolid, the acid is a white crystalline material with a strongtendency to absorb moisture from the air. In fact, phosphoricacid may also occur as a supercooled liquid at room tempera-ture. A supercooled liquid is one that remains in a liquid stateat temperatures below its freezing point, at which tempera-ture it would be expected to be a solid. As a liquid, phospho-ric acid is a colorless, odorless, syrupy liquid whose characteris sometimes described as sparkling.

Phosphoric acid was discovered independently as a com-ponent of bone ash in 1770 by two Swedish chemists, JohannGottlieb Gahn (1745–1818) and Karl Wilhelm Scheele (1742–1786). Four years later, Scheele discovered that the acid couldbe made by adding nitric acid to phosphorus.

Phosphoric acid is the ninth highest volume chemicalproduced in the United States. In 2004, the U.S. chemical

P

O

OHOH

HO


industry made about 5.2 million kilograms (11.5 millionpounds) of phosphoric acid. About 90 percent of that amountwent to the manufacture of fertilizers.

HOW IT IS MADE

The most economical method for making phosphoricacid is by treating phosphate rock with sulfuric acid(H2SO4). Phosphate rock is naturally-occurring rock withlarge amounts of calcium phosphate (Ca3(PO4)2). The pro-duct of this reaction is generally not very pure, but suffi-ciently pure for use in the production of fertilizers. Higherquality phosphoric acid can be made by burning phos-phorus or phosphate rock in an electric furnace, convertingeither to gaseous phosphoric oxide (diphosphorus pent-oxide; P2O5). The oxide is then dissolved in water to formthe acid.

Phosphoric acid. Red atomsare oxygen; white atoms arehydrogen; turquoise atom is

phosphorus. Gray stick shows adouble bond. P U B L I S H E R S



PHOSPHORIC ACID


By far the most important use of phosphoric acid isin the production of fertilizers. At least four major types offertilizers are made from phosphoric acid: diammoniumphosphate ((NH4)2HPO4; DAP), monoammonium phosphate(NH4H2PO4; MAP), granulated triple superphosphate (GTSP),and superphosphoric acid, the only liquid among the group.An additional 5 percent of the phosphoric acid produced isused as an animal feed supplement.

The remaining 5 percent of phosphoric acid produced isused in a very wide range of commercial, industrial, andhousehold products, including:

• For pickling cleaning and treating metallic surfaces,especially in the steel industry;

• In the synthesis of inorganic chemical compounds;

• As a catalyst in the manufacture of ethanol (ethyl alco-hol), ethylene, and other organic compounds;

• As a food additive in a number of products, such ascolas, beers, jams, and cheeses, where it adds a touchof tartness to the product;

• In the dentistry profession, where it is used to etch andclean teeth;

• In a number of consumer products, such as soaps, deter-gents, and toothpastes;

• As a refining and clarifying agent in the production ofsugar;

• In the dyeing of cotton;

Interesting Facts

• Phosphoric acid iscommercially available ina number of technicalgrades, ranging fromagricultural (relatively lowpurity) to technical (from

50 to 100 percent purity)to FCC (Food ChemicalsCodes) quality of at least75 percent phosphoricacid.


PHOSPHORIC ACID

• As a binder for cement;

• In the manufacture of waxes and polishes; and

• In water and sewage treatment plants.

Phosphates (compounds made from phosphoric acid) wereonce used widely as ‘‘builders’’ in detergents. A builder is acompound that increases the cleaning efficiency of the deter-gent. The problem is that phosphates that escape into thenatural environment can result in some undesirable changesin fresh water systems. Algae living in these systems usephosphate to grow and multiply, resulting in the conversionof fresh water lakes and ponds into swamps and bogs, and,eventually, into dry fields, a process known as eutrophica-tion. Because of this effect, the use of phosphates in deter-gents has been banned in most parts of the United States.

Phosphoric acid is an extremely hazardous and toxic com-pound. In small amounts, it causes irritation of the skin, eyes,and respiratory system. If ingested, it can cause serious damageto the digestive system, resulting in nausea, vomiting, abdom-inal pain, difficulty in breathing, shock, and occasionally deathby asphyxiation (suffocation). The most serious health hazardsposed by phosphoric acid are of concern primarily to peoplewho work with the product. The amount of phosphoric acidpresent in most domestic and household products is verysmall and poses little risk to users of those products.


‘‘Chemical of the Week: Phosphoric Acid.’’ Science Is Fun.http://scifun.chem.wisc.edu/CHEMWEEK/H3PO4/H3PO4.html(accessed on October 24, 2005).

Words to Know


PHOSPHATE A compound that is manu-factured from phosphoric acid

SUPERCOOLED Refers to a substance thatremains in a liquid state at temperaturesbelow its freezing point.


PHOSPHORIC ACID

‘‘Phosphate Primer.’’ Florida Institute of Phosphate Research.http://www1.fipr.state.fl.us/PhosphatePrimer (accessed onOctober 24, 2005).

‘‘Phosphoric Acid.’’ DC Chemical Co., Ltd.http://www.dcchem.co.kr/english/product/p_basic/p_basic04.htm (accessed on October 24, 2005).

‘‘Phosphoric Acid Fuel Cells.’’ Smithsonian Institution.http://americanhistory.si.edu/fuelcells/phos/pafcmain.htm(accessed on October 24, 2005).

See Also Nitric Acid; Sulfuric Acid


PHOSPHORIC ACID

OTHER NAMES:SBS

FORMULA:-[CH2CHC6H5-]n-

[-CH2CH=CHCH2-]n-[CH2CHC6H5-]n


COMPOUND TYPE:Organic polymer

STATE:Solid

MOLECULAR WEIGHT:Varies

MELTING POINT:160�C to 200�C

(320�F to 400�F)


SOLUBILITY:Insoluble in water

Poly(Styrene-Butadiene-Styrene)

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OVERVIEW

Poly(styrene-butadiene-styrene) (pol-ee-STYE-reen-byoo-tah-DYE-een-STYE-reen) is a thermoplastic block copolymer ofstyrene and butadiene. The compound is often called simplySBS or SBS rubber. A thermoplastic polymer is one thatcan be converted back and forth between liquid and solidstates by alternate heating and cooling. A copolymer is apolymer made from two monomers, in this case, styrene(C6H5CH=CH2) and 1,3-butadiene (CH2=CHCH=CH2). The termblock copolymer means that one section of the polymerchain consists of polystyrene (-[CH2CHC6H5-]n to which isconnected another section consisting of polybutadiene(-[-CH2CH=CHCH2-]n), which, in turn, is connected to anothersection of polystyrene (-[CH2CHC6H5-]n), and so on.

A copolymer like SBS has properties of both polymers ofwhich it is composed. In the case of SBS, the polystyrenesegments give the product strength and durability, while thepolybutadiene segments provide flexibility. The substanceacts like natural rubber at room temperature, but becomes

C

H

H

H

C

C C C

HH

H

H

H

H

H

CCH H C

C

C

CH

H

H

H

C

C

C

H HHH H

CCC

CC

n

C


soft and plastic when heated. The latter property means thatproducts made of SBS can be formed into a variety of shapes.

SBS is resistant to abrasion and does not readily breakdown when exposed to heat, light, and chemicals. It maydissolve or break down when exposed to fats and oils andvarious types of hydrocarbon compounds and mixtures. Itmaintains its structure and performance well over a widetemperature range from �60�C to 150�C (�75�F to 300�F).

SBS was first developed in the early 1930s by two Germanchemists, Walter Bock and Eduard Tschunkur. Their researchwas part of Germany’s Four Year Plan for self-sufficiency.Under that plan, the nation worked toward eliminating, sofar as possible, the import of essential materials that might beneeded in case of a war. Germans already had one type ofsynthetic rubber, known as Buna, but it had a number ofdisadvantages. SBS was far superior to Buna, and was soonbeing produced in very large amounts in German factories.

HOW IT IS MADE

Molecules of both styrene and 1,3-butadiene contain dou-ble bonds. Any compound with double bonds has the ability

Poly (styrene butadiene

styrene). White atoms arehydrogen; black atoms are

carbon; and turquoise atomsshow where this molecule joinsto other ones to form chains.

P U B L I S H E R S R E S O U R C E

G R O U P


POLY(STYRENE BUTADIENE STYRENE)

to form polymers. Polymerization occurs when the doublebond in one monomer molecule (such as styrene) breaksapart. A hydrogen atom from a second molecule of the mono-mer then adds on to one end of the broken double bond. Therest of the second molecule adds to the other end of thebroken double bond. A ‘‘double-molecule,’’ consisting of twomonomers joined to each other, forms. The ‘‘double-molecule’’also contains a double bond. So the process can be repeated toform a ‘‘triple-molecule’’ consisting of three monomer mole-cules. The process is repeated hundreds or thousands of timesproducing a long chain of monomers.

In the production of a block copolymer, one extra step isadded. First, a long chain of styrene monomers is produced.Then a long chain of butadiene monomers is made. Next, thetwo chains are joined to each other. Finally, additional chainsof polystyrene and polybutadiene are added, making a verylong chain consisting of alternating blocks of polystyreneand polybutadiene.

This method is used for the production of many differentkinds of polymers. The most difficult problems may be (1)how to get the first few double bonds to break apart, and (2)how to stop the polymerization reaction at just the rightpoint. The method used to make most SBS today involvesthe use of a butyl lithium (C4H9Li) catalyst, which is veryeffective in getting the reaction started. The reaction isterminated at some given point by the addition of dichlor-odimethylsilane (SiCl2(CH3)2). The dichlorodimethylsilanereacts with the last monomer at the end of the SBS chain,blocking the addition of any additional styrene or butadienemonomers.


The process by which SBS is made can be modified toproduce products with somewhat different physical and che-mical properties. For example, some forms of SBS are espe-cially strong, making them suitable for the manufacture oftires, shoe soles, conveyer belts, and the tracks on caterpillartrucks. Other types of SBS are engineered to be more flex-ible, for use as rubber tubing, flexible toys, sporting goods,and refrigerator gaskets. SBS products can also be made in avariety of colors and shapes for use as seals, rubber mats,floor coverings, tire treads, and shoe components.



SBS production fluctuates or changes according to anumber of factors, including market demand, the price ofpetroleum, and the price of natural rubber. For example,when natural rubber is readily available and inexpensive,the demand for synthetic types of rubber, such as SBS,decreases. Also, when the price of petroleum increases, SBSbecomes more expensive to make and production decreases.


Dick, John S., and R. A. Annicelli, eds. Rubber Technology:Compounding and Testing for Performance. Cincinnati, OH:Hanser Gardner Publications, 2001.

Johnson, Peter S. Rubber Processing: An Introduction. Cincinnati,OH: Hanser Gardner Publications, 2001.

‘‘SBS Rubber.’’ University of Mississippi, Polymer Science LearningCenter.http://www.pslc.ws/mactest.sbs.htm (accessed on October 26,2005).

See Also 1,3-Butadiene; Polystyrene; Styrene

Words to Know

COPOLYMER A polymer made with twodifferent monomers.

MONOMER A small molecular unit that joinswith others to form a polymer.


THERMOPLASTIC A material that becomessoft and moldable when heated, thenhardens when it is cooled.



FORMULA:Varies


oxygen


STATE:Solid

MOLECULAR WEIGHT:Very large; varies

MELTING POINT:Varies



SOLUBILITY:Virtually insoluble in

water

Polycarbonates

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OVERVIEW

Polycarbonate (pol-ee-KAR-bun-ate) is a term used bothfor a specific compound and for a class of compounds withsimilar chemical structures. The members of this familyare made by reacting phosgene (COCl2) with any compoundhaving two phenol structures. Phenol is hydroxybenzene,C6H5OH. The most common polycarbonate is made in thereaction between phosgene and bisphenol A (C6H5OHC(CH3)2-

C6H5OH). Polycarbonates are sold under a number of tradenames, including Cyrolon�, Lexan�, Markrolon�, Merlon�,Tuffak�, and Zelux�.

Polycarbonates are strong, lightweight plastics that areresistant to heat, light, chemicals, and physical shock. Theyare used in a number of commercial and industrial productsranging from consumer electronics to sporting goods tostorage containers.

The original polycarbonate was discovered in 1953 by theGerman chemist Hermann Schnell (1916–1999), an employeeat the Bayer AG chemical company. The product was discovered

n

H

H H

H

C C

C C

C CC

H

H H

H

C C

C C

C C

OCH3

CH3

C O O


almost simultaneously in the United States by chemistDaniel W. Fox (1923–1989) at the General Electric Company.Commercial use of the product began in the late 1950s, withthe first large-scale production plant beginning operation in1960. At first, polycarbonate was used primarily for electri-cal devices such as fuse boxes. In 1982, compact discs (CDs)were introduced and were made almost entirely of polycar-bonate. Fifteen years later, polycarbonate digital videodiscs(DVDs) entered the market. In the mid-1980s, polycarbonatebottles began to replace the more cumbersome and break-able glass bottles. Today, polycarbonates are used for dozensof commercial applications.

HOW IT IS MADE

Polycarbonates are made in the reaction between phos-gene and any compound containing two phenol groups, suchas bisphenol A . One chlorine atom from the phosgene com-bines with a hydrogen atom from the hydroxyl group (-OH)in each phenol to make hydrogen chloride (HCl). As thehydrogen chloride is removed from the reaction, the phos-gene remnant links with the phenol remnant. As the reactionproceeds, the phosgene-phenol grouping grows longer and

Polycarbonate. Red atoms areoxygen; black atoms are carbon;white atoms are hydrogen. Gray

sticks indicate double bonds.Striped sticks show benzene

rings. P U B L I S H E R S R E S O U R C E

G R O U P


POLYCARBONATES

longer, eventually forming a large, straight-chain polymer ofpolycarbonate.

Other types of polycarbonates have also been made usinga very different approach from that involving bisphenolA and related compounds. For example, the reaction betweenphosgene and allyl alcohol (CH2=CHCH2OH) produces a mono-mer with carbon-carbon double bonds at both ends of themolecule that can be used for polymerization. Interestinglyenough, the polycarbonate produced by this process has verydifferent physical properties from the traditional bisphenolA polymer. The allyl polymer is a clear, transparent, flexibleplastic whose primary use is in the production of eyeglasslenses.


Polycarbonates are strong, heat resistant, and light-weight, making them ideal for applications in construction,electronics, automobiles, and appliances. Many polycarbo-nates are substituted for glass in safety and athletic goggles,building components, and car instrument panels becausethey are transparent, yet shatterproof. They are also moreresistant to ultraviolet radiation than is glass. Some of thespecific products made with polycarbonates include:

• Consumer electronic devices, such as cell phones, com-puters, pagers, and fax machines;

• Data storage devices, such as CDs and DVDs;

• Automobile parts, including tail lights, turn signals, foglights, and headlamps;

• Appliances such as refrigerators, food mixers, hairdryers, and electric shavers;

• Safety devices, including helmets, goggles, and bullet-proof windows;

Interesting Facts

One of polycarbonateplastics most interesting

uses is in the manufacture ofbulletproof windows.


POLYCARBONATES

• Healthcare devices, such as incubators, kidney dialysismachines, and eyeglasses.

The U.S. Food and Drug Administration has acceptedpolycarbonates as safe for use with foods. There is littleevidence that the compounds have any harmful healtheffects on humans. Minimal evidence exists to suggest thatbisphenol A may have some harmful effects on experimentalanimals. But there is no evidence that similar effects occur inhumans, and the amount of free bisphenol A in polycarbo-nates is so small as to be negligible.


Lazear, N. R. ‘‘Polycarbonate: High Performance Resin.’’ AdvancedMaterials & Processes (February 1995): 43 45.

‘‘Polycarbonate.’’ Association of Plastics Manufacturers in Europe.http://www.plasticseurope.org/content/default.asp?PageID=43(accessed on October 24, 2005).

‘‘Polycarbonate (Makrolon�, Lexan�, Zelux�).’’ San Diego Plastics.http://www.sdplastics.com/polycarb.html (accessed on October24, 2005).

‘‘Polycarbonate Plastics.’’ Bisphenol A.http://www.bisphenol a.org/human/polyplastics.html (accessedon October 24, 2005).

‘‘Polycarbonates.’’ Polymer Science Learning Center.http://www.pslc.ws/mactest/pc.htm (accessed on October 24,2005).

Words to Know



POLYCARBONATES

OTHER NAMES:Ethene homopolymer

FORMULA:-[-CH2-CH2-]-n



STATE:Solid

MOLECULAR WEIGHT:1,500 to 100,000 g/

mol

MELTING POINT:Varies: about 85�C

–110�C (185�F–230�F)




most organicsolvents; soluble in

hydrocarbons andhalogenated

hydrocarbons

Polyethylene

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OVERVIEW

Polyethylene (pol-ee-ETH-uh-leen) is a thermosetting whitesolid resistant to high temperatures, most inorganic andorganic chemicals, and physical impact. It is also an electricalnon-conductor. A thermosetting polymer is one that, once it ismelted and formed, can not be re-melted. Polyethylene is avail-able in a variety of forms, the most common of which are high-density (HD or HDPE), low density (LD or LDPE), linear lowdensity (LLD or LLDPE) and cross-linked (CLPE). These forms ofthe compound differ with respect to the structure of the poly-ethylene chains and their relationship to each other. For exam-ple, if all of the polyethylene chains are straight chains withoutbranches, they can pack together tightly forming a high den-sity product. By contrast, low density polyethylene consists ofshorter chains with many side branches on them. The sidebranches prevent adjacent polymer chains from getting tooclose to each other. In cross-linked polyethylene, adjacent poly-mer chains actually form chemical bonds with each other,holding them in a regular, almost crystalline pattern.

H H

H H n

CC


Polyethylene was first prepared accidentally in 1889 bythe German chemist Hans von Pechmann (1850–1904). VonPechmann was heating diazomethane (H2C=N=N) when heobserved the formation of a white, waxy solid. When hiscolleagues identified the substance as containing repeatedmethylene (-CH2) units, they called the material polymethy-lene. Von Pechmann did not pursue his discovery, nor did anyof his colleagues until the 1930s. Then, in 1933, two chemistsat the English firm of Imperial Chemicals Industries (ICI),Reginald Gibson and Eric Fawcett, accidentally re-discoveredpolyethylene. While attempting to pressurize a mixture ofethylene and benzaldehyde, Gibson and Fawcett observed theformation of a white waxy solid within the pressure vessel.At first, they were unable to account for this reaction. Even-tually, however, they discovered that a tiny hole in thepressure vessel had allowed oxygen to seep into the tank,catalyzing the conversion of ethylene to polyethylene. Twoyears later, two other ICI chemists, J. C. Swallow and M. W.Perrin duplicated the Gibson-Fawcett experiment and devisedan efficient commercial method for making the polymer.

Beginning in the 1950s, researchers in a number ofcountries began to explore the use of catalysts to increasethe efficiency of reactions by which polyethylene is made.For example, Robert Banks and John Hogan at Phillips Pet-roleum invented a procedure using chromium trioxide(Cr2O3) for the preparation of high-density polyethylene andanother form of the product known as crystalline polyethy-lene. In 1953, the German chemist Karl Ziegler (1898–1973)

Polyethylene. White atoms arehydrogen and black atoms are




POLYETHYLENE

used titanium halides and organoaluminum compounds tomake polyethylene under even lower temperatures and pres-sures. And in 1976, the German chemists Walter Kaminsky(1941–) and Hansjorg Sinn (1929–) invented a third method ofproduction using metallocenes (organic compounds that con-tain a metal) as a catalyst.

HOW IT IS MADE

Polyethylene is made by polymerizing ethylene (ethene;CH2=CH2). Polymerization occurs when the double bond inethylene breaks, allowing one molecule of ethylene to com-bine with a second molecule of ethylene: CH2=CH2+ CH2=CH2

! CH3CH2CH=CH2. The product of that reaction also containsa double bond, allowing the reaction to be repeated:CH3CH2CH=CH2 + CH2=CH2 ! CH3CH2CH2CH2CH=CH2. Onceagain, the final product contains a double bond, and thereaction can be repeated again and again and again.

Polymerization occurs when some outside agent providesthe energy to break the double bond in ethylene to get thereaction started. Heat, light, ultraviolet radiation, a beam ofelectrons, and gamma rays have all been used to initiate poly-merization. Polymerization occurs at lower energy levels, andit has been the search for catalysts to achieve this objective

Interesting Facts

Phillips Petroleum haddifficulty maintaining qualitycontrol in the early years ofmaking polyethylene. As aresult, it produced largequantities of the productthat could not be sold forcommercial, industrial, orhousehold use. The companyfaced financial ruin. Fortunately, a new toy came intoexistence in the mid 1950s,the hula hoop. A hula hoop issimply a ring of plastic that

could be made with low gradepolyethylene. The firstcompany to market hulahoops, called Wham O, boughtup much of Phillips’ defectivepolyethylene stock for itshula hoops. The company soldmore than twenty millionhula hoops in its first sixmonths of existence at a costof $1.98 each. Wham O was abooming success, and it savedPhillips from financial ruin.


POLYETHYLENE

that have led to the processes developed by Banks andHogan, Ziegler, Kaminsky and Sinn, and other researchers.


An estimated 55 million metric tons (60 million short tons)of polyethylene are produced worldwide each year. In the Uni-ted States, an estimated 7 million metric tons (8 million shorttons) of high-density polyethylene will be produced in 2006 andan estimated 2.7 million metric tons (3.0 million short tons) oflow-density polyethylene will be made. The greatest fraction ofHDPE is used in the manufacture of molded products, film andsheeting, pipes and tubing, fibers, and gasoline and oil contain-ers. The most important application of LDPE is in the manu-facture of packaging films for foods as well as coatings that aresprayed or otherwise applied to all kinds of surfaces. It is alsoused widely to make liners for drums and other shipping con-tainers, wire and cable coating, trash bags, squeeze bottles,inexpensive dinnerware, drop cloths, swimming pool covers,toys, and electric insulation.

No health hazards from polyethylene in any form haveyet been identified.


Meikle, Jeffrey L. American Plastic: A Cultural History.http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc14/icsc1488.htm (accessed onOctober 24, 2005).

‘‘Polyethylene.’’ In World of Invention. 2nd ed. Edited by KimberleyA. McGrath and Bridget Travers. Detroit, MI: Gale, 1999.

‘‘Polyethylene Specifications.’’ Boedeker Plastics. http://www.boedeker.com/polye_p.htm (accessed on October 24, 2005).

See Also Polypropylene

Words to Know




POLYETHYLENE

OTHER NAMES:Acrylic, PMMA

FORMULA:-[-CH2C(CH3)

(COOH)CH2-]-n


oxygen


STATE:Solid

MOLECULAR WEIGHT:Varies: 250,000 to

over 1,000,000 g/mol

MELTING POINT:Varies: usually above

100�C (200�F)



best solvents aremixtures of two or

more organicsolvents, aromatic

hydrocarbons,halogenated hydro-

carbons, andtetrahydrofuran

PolymethylMethacrylate

KE

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OVERVIEW

Polymethylmethacrylate (POL-ee-meth-uhl-meth-AK-rill-ate)is a clear thermoplastic resin used to make windshields, visors,coatings for baths, advertising signs, and contact lenses. It is alsowidely used in dentistry and medicine. A thermoplastic resin isone that becomes soft when heated and hard when cooled. It canbe converted back and forth any number of times between thesolid and liquid states by further heating and cooling.

Polymethylmethacrylate (PMMA) is more transparentthan glass and six to seventeen times more resistant tobreakage than glass. Another advantage it has over glass isthat, if it does break, it falls apart into dull-edged pieces.PMMA is resistant to water, inorganic acids and bases, but isvulnerable to many organic solvents.

PMMA was first synthesized in 1928 in the laboratories ofthe German chemical firm Rohm and Haas. After five yearsof research, one of the firm’s founders, Otto Rohm, found away of manufacturing sheets of polymethylmethacrylate. Hepatented his invention and the company was soon producing the

H

C CH2CH2

CH3

C O n

O

– –


product under the trade name of Plexiglas�. At about thesame time, the product was being developed independentlyin the United States by the Dow chemical company, whosold its product under the trade name of Lucite�. Over time,a number of other chemical companies produced their ownversion of PMMA under a variety of trade names, includingAcrylite�, Acrypet�, Crinothene�, Degalan�, Diakon�,Elvacite�, Kallocryl�, Metaplex�, Osteobond�, Paraglas�,Perspex�, Pontalite�, Sumipex�, Superacryl�, and Vedril�.

HOW IT IS MADE

The monomer from which polymethylmethacrylate ismade is methyl methacrylate, CH2=C(CH3)COOCH3. Methyl

Poly(methyl methacrylate).

Red atoms are oxygen; whiteatoms are hydrogen; black

atoms are carbon. Gray stickshows a double bond.



POLYMETHYL METHACRYLATE

methacrylate is made in the reaction between acetone cyano-hydrin ((CH3)2COHCN) and methanol (methyl alcohol; CH3OH)in the presence of a sulfuric acid catalyst. As with all polymers,methyl methacrylate can be polymerized by a number ofagents, including heat, radiation, and certain chemicals knownas free-radical initiators. Once polymerization of methyl metha-crylate begins, it can be processed in a number of ways. One ofthe most common processing system used involves passingthe liquid material between two polished stainless steel belts.The distance between the belts is set to the desired thicknessfor the acrylic sheet. The acrylic is cured by a process of coolingand heating after leaving the steel belt. The final product isthen cut to desired lengths at the end of the production line.


The most common use for PMMA is as a glass substitute.PMMA offers many benefits over glass because it is moretransparent, less dense, stronger, and shatterproof. In ophthal-mology (the branch of medicine that deals with diseases of theeye and their treatment), PMMA is used to make replacementlenses for the eye when the original lens has been removed for

Interesting Facts

• Polymethylmethacrylateexhibits a phenomenonknown as total internalreflection. That term meansthat a light beam trans-mitted through a solid tubemade of PMMA reflects offthe inner surface of thetube. This property allows alight beam to be trans-mitted around corners andbends and out the end of atube made of PMMA.

• A black-light reactive tatooink made from PMMA and

microspheres of fluores-cent dye is used on wildlifeto track activities such asmigration and growth pat-terns.

• The spectator shield inhockey arenas is madeof PMMA.

• Plexiglas� was exhibitedby Rohm & Haas at theWorld’s Trade Fair in Parisin 1937. One of the exhibitswas a transparent violinmade from the product.



some reason, such as the growth of a cataract. It is also used tomake hard contact lenses. Other medical and dental applica-tions of the material include its use as a dental cement, for themanufacture of bases and linings for dentures (false teeth),and to make a bone cement used in the reconstruction ofbroken or damaged bones and to fix implants in place.

Powdered polymethylmethacrylate presents healthhazards because it may cause irritation of the skin, eyes,and respiratory tract. This hazard is of concern to peoplewho work with the material in its raw form.

The glass-like material with which most people come intocontact poses no health hazard for humans.


‘‘Material Information Polymethylmethacrylate, PMMA, Acrylic.’’Goodfellow.http://www.goodfellow.com/csp/active/static/E/ME30.HTML(accessed on October 24, 2005).

Meikle, J. L. American Plastic: A Cultural History. New Brunswick,N.J.: Rutgers University Press, 1997.

‘‘More on the Manufacturing of Acrylic Sheet.’’ Plastics Distribu

tor & Fabricator Magazine (November/December 2000).Available online athttp://www.plasticsmag.com/features.asp?fIssue=Nov/Dec 00&aid=3053 (accessed on October 24, 2005).

‘‘Polymethylmethacrylate.’’ Kids’ Macrogalleria. University of Southern Mississippi, The Polymer Science Learning Center.http://www.pslc.ws/macrog/kidsmac/pmma.htm (accessed onOctober 24, 2005).

‘‘Plexiglas� Primer.’’ Ridout Plastics.http://www.ridoutplastics.com/plexprim.html (accessed on October 24, 2005).

Words to Know

CATALYST a material that increases the rateof a chemical reaction without undergoingany change in its own chemical structure.

MONOMER one of the small, relativelysimple molecules from which polymersare made.



OTHER NAMES:Propylene polymer;

1-propenehomopolymer

FORMULA:-[-CH(CH3)CH2-]-n



STATE:Solid

MOLECULAR WEIGHT:Very large; 40,000 g/

mol and up

MELTING POINT:Varies: 165�C–170�C

(330�F–340�F)


SOLUBILITY:Insoluble in water andcold organic solvents;

softens in warmorganic solvents, but

does not dissolve;soluble in hydrocar-

bons and halogenatedhydrocarbons

Polypropylene

KE

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OVERVIEW

Polypropylene (pol-ee-PRO-pih-leen) is a translucentwhite solid that is resistant to attack by heat, abrasion,inorganic acids and bases, most organic materials, and bac-teria and fungi. It has high electrical resistance and tensilestrength (its resistance to being pulled apart) and is veryflexible. It takes on color well and can be coated with chrome.It can be prepared in a number of shapes and forms byextrusion and molding. Polypropylene is a thermoplasticpolymer, meaning that it can be heated and cooled repeat-edly, changing from a solid to a liquid and back again. Poly-propylene is currently available under a number of tradenames, including Amco�, Amerfil�, Azdel�, Beamette�,Clysar�, Daplen�, Dexon�, Epolene�, Gerfil�, Herculon�,Lambeth�, Lupareen�, Meraklon�, Mitsui Polypro�, Noblen�,Novolen�, Pellon�, Polypro�, Profax�, Propathene�,Propolin�, Propophane�, Shoallomer�, and Tuff-Lite�. Consid-erable dispute exists as to who should receive credit for invent-ing propylene. According to one history of the compound, it

C

H

H CH3 n

H

C


was discovered independently about nine times. Patent dis-putes over the discovery lasted from the 1950s to 1989,when official credit was finally given to two researchers atthe Phillips Petroleum Company, J. Paul Hogan (1919–) andRobert Banks (1921–1989). Phillips began selling polypropy-lene in 1951 under the trade name of Marlex�.

Much of the early research on polypropylene was con-ducted by the Italian chemist Giulio Natta (1903–1979), thenan employee at the Italian chemical firm of Montecatini.While working earlier on the development of a related com-pound, polyethylene, Natta discovered some of the funda-mental principles that governed the successful commercialproduction of polymers. In 1957, Montecatini began producingits own version of polypropylene. Six years later, Natta and hiscolleague, German chemist Karl Ziegler (1898–1973) sharedthe Nobel Prize in chemistry for their research on polymers.

HOW IT IS MADE

Polypropylene is made by the polymerization of propy-lene (propene; CH3CH=CH2). Polymerization is the process bywhich a single monomer unit (propylene in this case) isadded to a second monomer of the same kind. The procedureis then repeated over and over again. Each time anothermonomer is added to the growing chain, the molecule getslarger and larger. Normally, polymerization is initiated byany of a number of agents, including radiation, light, or heat.

Polypropylene. White atomsare hydrogen and black atoms




POLYPROPYLENE

Polymerization of propylene presents a somewhat differ-ent problem, however, because of the presence of methyl(-CH3) groups extending off the main chain of the molecule(-[-CH(CH3)CH2-]-n). If polymerization is allowed to proceed onits own, some methyl groups will extend in one directionfrom the main chain, and others in a different direction.The product of this reaction is an amorphous product, onewithout crystalline shape, that has only a few very limiteduses. To produce crystalline polypropylene, with all the desir-able properties noted above, polymerization must be con-trolled to make sure that all methyl groups are on the sameside of the main chain. One of Natta and Ziegler’s greatcontributions was the discovery of catalysts capable ofachieving the correct orientation of methyl groups. Theyfound that metal halides, such as titanium chloride, couldproduce this effect. More recently, the German chemist Wal-ter Kaminsky (1941–) and his colleagues found another groupof catalysts that could polymerize crystalline polypropyleneeven more efficiently, a group of compounds called metallo-cenes. The manufacture of polypropylene today dependsheavily on the use of such catalysts.


About one-third of all the polypropylene consumed in theUnited States is used to make fibers, for the manufacture ofproducts such as blankets, fabrics, carpets, yarns, fish nets,protective clothing, laundry bags, and ropes. The next largest

Interesting Facts

• Natta applied for a patentfor polypropylene beforetelling Ziegler of hissuccess in making thecompound. Ziegler was soangry that the two mendid not speak for manyyears. They reconciledonly when they were both

awarded the Nobel Prizeat the same time.

• Australian bank notes(paper money) are madefrom polypropylene, whichmakes them more durablethan paper bills.


POLYPROPYLENE

uses are in the production of rigid packaging materials, suchas crates, food containers, and bottles; in household products,such as dishes, bowls, outdoor carpeting, and outdoor furni-ture; and in packaging film. Hospitals use many surgicalobjects made out of polypropylene, taking advantage of itslow cost and ability to be sterilized. Automobile manufac-turers use the compound almost everywhere on the body oftheir cars. About 20 percent of all the polypropylene pro-duced is used to make a large variety of products, includingwire and cable insulation, medical tubing, pipe fittings, bat-tery cases, drinking straws, and packaging foam.

No human health hazards have been identified for poly-propylene in the form in which most people come into con-tact with the compound.


Karger Kocsis, J. Polypropylene An A Z Reference. New York:Springer Verlag, 1998.

Meikle, Jeffrey L. American Plastic: A Cultural History. Piscataway, N.J.: Rutgers University Press, 1997.

‘‘Polypropylene.’’ The Macrogalleria. Polymer Learning Center,University of Southern Mississippi.http://www.pslc.ws/macrogcss/pp.html (accessed on October24, 2005).

‘‘Polypropylene.’’ World of Chemistry. Edited by Robyn V. Young.Detroit, Mich.: Gale, 1999.

See Also Polyethylene

Words to Know

CATALYST a material that increases the rateof a chemical reaction without undergoingany change in its own chemical structure.

POLYMER a compound consisting of verylarge molecules made of one or twosmall repeated units called monomers.


POLYPROPYLENE

OTHER NAMES:Siloxane;

organosiloxane;silicone

FORMULA:Varies

ELEMENTS:Varies: Silicon

(always), oxygen(always), carbon(almost always),

hydrogen (almostalways)

COMPOUND TYPE:Inorganic polymer

STATE:Solid or liquid


MELTING POINT:Varies


SOLUBILITY:Varies

Polysiloxane

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OVERVIEW

The term polysiloxane (pol-ee-sill-OK-sane) refers to aclass of compounds whose molecules consist of a silicon-oxygen backbone (-Si-O-Si-O-Si-O-Si)n arranged either in a linearor cyclic (ring) pattern. Each silicon in the chain has twoadditional oxygen atoms attached to it. In many cases, thepolysiloxanes also have one or more alkyl groups attached tothe main chain replacing one or more of the oxygens. Analkyl group is an alkane, a saturated hydrocarbon, lackingone hydrogen atom. Examples of alkyl groups are the methyl(-CH3) and ethyl (-CH2CH3) groups. In one common type ofsiloxane, all of the oxygens that are not a part of the back-bone of the chain are replaced by methyl groups. Polysilox-anes that contain alkyl groups are known as organosiloxanesor, more commonly, silicones.

Researchers have now learned how to modify organosi-loxane polymers by using various alkyl groups in chains ofvarious lengths and conformations to produce a very widearray of products. All are organosiloxanes, but with very

CH3

CH3

CH3

CH3

CH3

CH3

OSi O Si

n

Si


different physical and chemical properties and, hence,with very different applications. They range from liquid togel to a semi-solid, rubber-like material. In general, the orga-nosiloxanes tend to be chemically inert and resistant to heat.Although not identical, the terms polysiloxane, siloxane, andorganosiloxane, and silicone are often used interchangeably.

The chemistry of silicon has long fascinated chemists.The element lies just below carbon in the periodic table,meaning that its physical and chemical properties aresimilar to carbon from which millions of organic com-pounds are made. The hope has long been to discover ifsilicon also can make a diverse number of compounds, ascarbon can. One researcher who pursued this question inthe early twentieth century was the English chemistFrederic Stanley Kipping (1863–1949). Kipping made use ofa new kind of chemical reaction, called the Grignard reac-tion, after the French chemist Victor Grignard (1871–1935)who invented it. With the Grignard reaction, Kipping wasable to make a number of silicon compounds to whichwere bonded alkyl groups in a variety of conformations.These compounds were the first organosiloxanes producedand studied in any detail, earning Kipping the title of‘‘Father of Silicone Chemistry.’’ During his lifetime, Kippingwrote more than 50 scholarly papers on his work. He didnot, however, see the possibility of commercial applicationsfor his discoveries.

Polysiloxane. Red atomsare oxygen; white atoms

are hydrogen; black atoms arecarbon; and turquoise atoms

are silicon. P U B L I S H E R S



POLYSILOXANE

The commercialization of silicones did not become possi-ble until the early 1940s when a research chemist at theGeneral Electric Company, E. G. Rochow (1909–2002) foundan efficient way of making organosiloxanes in large quanti-ties. Rochow’s discovery came at an opportune time, thebeginning of World War II. A number of military applica-tions were found for the new product almost immediately.Within five years, a number of major chemical companies,including General Electric, Dow-Corning, Union Carbide,Stauffer Chemical, Wacher-Chemie, and Farbenfabriken BayerA. G., had begun making organosiloxanes in large quantities.

HOW IT IS MADE

A variety of production methods is available for makingdifferent types of organosiloxanes. Probably the most popu-lar approach begins with the reduction of silicon dioxide(sand; SiO2) in an electric furnace. In that reaction, thesilicon dioxide breaks down into silicon and oxygen: SiO2 !Si + O2. The silicon is then treated with methyl chloride(CH3Cl), which produces a mixture of methylchlorosilanes.Methylchlorosilanes are compounds that contain a singlesilicon atom to which are attached one or more methylgroups and one or more chlorine atoms. The methylchlorosi-lane produced in largest amount is dimethyldichlorosilane,(CH3)2SiCl2. When this compound is treated with water, allof the chlorines are replaced by oxygens and the resultingcompound polymerizes spontaneously. That is, individualmolecules of the newly-formed silicon-carbon-oxygen com-pound begin to react with each other to form long organosi-loxane chains. The size and character of the chain can becontrolled by adding compounds that stop the polymerizationreaction at some given point, resulting in the formation of aliquid, a gel, a semi-solid, or some other form of the product.


Organosiloxanes are very heat resistant, so they do noteasily melt, like most other organic compounds. They are alsowater-repellant and can withstand extremes of sunlight,moisture, cold, and attack by most chemicals. These proper-ties make them useful for protective coatings, electricalinsulation, adhesives, lubricants, paints, and rubber-likematerials. Some silicones are also used to make nonstick


POLYSILOXANE

surfaces, such as pans and spatulas for the kitchen. They arealso used in making other kitchen items, such as oven mitts,because of their heat resistance.

Methyl silicones are also a major ingredient in personalcare products. They are added to shaving lotions to providelubrication and to give these products a non-greasy, yet silky,feeling. They help hair-styling products to spread moreeasily, and they increase the skin protection factor (SPF) insunscreens. Silicones are also used in deodorants, perfumes,and nail polishes.

Some industrial and commercial applications of siliconesinclude:

• As adhesives and sealants in many aircraft parts,including doors, windows, wings, fuel tanks, hydraulicswitches, overhead bins, wing edges, leading gear elec-trical devices, vent ducts, engine gaskets, electricalwires and black boxes;

Interesting Facts

• One of the most famousfootprints in the world—that made by NeilArmstrong during hislanding on the Moon in1969—was made with a bootwith a silicone rubber sole.

• Silicone was first used forbreast implants in the1960s for women who hadundergone mastectomies,surgical removal of theirbreasts. Silicone implantslater became popular withwomen who had nomedical problems, butwanted larger breasts. Bythe 1980s, many womenwith breast implants

began complaining of pain,chronic fatigue,inflammation of breasttissue, and other medicalproblems thought to beassociated with theirsilicone breast implants.Some of these women suedBristol-Meyers Squibb,Dow Chemical, 3M, andother companies who madesilicone for breastimplants. By 1995, morethan 20,000 legal claimshad been brought againstDow alone. Faced with thisstaggering number ofclaims, the company wentbankrupt.


POLYSILOXANE

• In the construction business as sealants for all kinds ofbuilding materials, including concrete, glass, granite,steel and plastic;

• In the manufacture of many automobile parts, includ-ing air bags, gaskets, headlamps, hydraulic bearings,ignition cables, radiator seals and hoses, shock absor-bers, spark plug boots and ventilation flaps;

• As heat transfer agents;

• For the weatherproofing of concrete and other surfaces;

• In the production of surgical membranes and implants;

• In a great variety of electrical and electronic appliances,devices, and parts, including computer cases, key-boards, copy-machine components, and telephones; and

• For providing attractive and sturdy finishes for fabricand clothing.


‘‘The Basics of Silicon Chemistry.’’ Dow Chemical Company.http://www.dowcorning.com/content/sitech/sitechbasics/silicones.asp (accessed on October 26, 2005).

‘‘Heat and Chemical Resistant Silicone Rubber. Silicones 2. OrganicSilicon Chemistry.’’ ChemCases.com Kennesaw State University.http://www.chemcases.com/silicon/sil2cone.htm (accessed onOctober 26, 2005).

‘‘Silicones.’’ Macrogalleria, University of Southern Mississippi.http://www.pslc.ws/macrogcss/silicone.html (accessed onOctober 26, 2005).

Words to Know

ALKANE a hydrocarbon where all the bondsbetween atoms are single bonds, thecarbons are linked in a chain (except formethane, CH4), and every carbon atom issaturated, or bonded to the maximumnumber of hydrogen atoms.

ALKYL GROUP an alkane that is lacking onehydrogen atom.

HYDROCARBON a chemical that consists ofcarbon and hydrogen.


POLYSILOXANE

‘‘Silicones Science On Line.’’ Centre Europeen des Silicones.http://www.silicones science.com/ (accessed on October 26, 2005).

‘‘What Are Silicones?’’ Silicones Environmental, Health and SafetyCouncil of North America.http://www.sehsc.com/index.asp (accessed on October 26, 2005).


POLYSILOXANE

OTHER NAMES:Styrofoam

FORMULA:-[-CH2C6H5-]-n



STATE:Solid

MOLECULAR WEIGHT:Varies g/mol

MELTING POINT:Varies widely; ranges

from 190�C–260�C(370�F–500�F)


SOLUBILITY:Insoluble in water

and inorganic acidsand bases; soluble

in many organicsolvents, including

ethylbenzene,chloroform, carbon

tetrachloride, andtetrahydrofuran

Polystyrene

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OVERVIEW

Polystyrene (pol-ee-STYE-reen) is a thermoplastic poly-mer made from styrene. A thermoplastic polymer is amaterial that can be repeatedly softened and hardened byalternately heating and cooling. Styrene is a hydrocarbonderived from petroleum with the formula C6H5CH=CH2.The presence of the double bond in the styrene moleculemakes it possible for styrene molecules to react witheach other in long chains that constitute the polymerpolystyrene.

Polystyrene is a hard, strong, transparent solid highlyresistant to mechanical impact. It is an excellent thermal(heat) and electrical insulator, is easily shaped and moldedin the liquid state, and takes dyes readily. It can be producedin a wide variety of shapes and forms, including sheets,plates, rods, beads, and foams.

The history of polystyrene dates to 1839 when a Germanapothecary (druggist) named Eduard Simon discovered styr-ene in petroleum. Later scientists attempted to incorporate

C

CC

H

H

CH

H HC

C C

H

HC

H

n


styrene into some of the commercial products they made,such as rubber tires. But a polymer based on styrene wasnot actually produced until 1930 when researchers at theGerman chemical firm of I. G. Farben discovered how to makethe material. Farber’s parent company, BASF, shortly madethe product commercially available and in 1937, Dow Chemi-cal first made the compound available in the United States.During World War II, polystyrene was used for the manufac-ture of synthetic rubber products. After the war, the numberof commercial and industrial uses expanded rapidly. Today, itis virtually impossible to avoid polystyrene products in one’sdaily life.

HOW IT IS MADE

Compounds like styrene with double bonds often poly-merize easily. The double bond on a styrene molecule breaksopen and a hydrogen atom from a second styrene moleculeadds to one side of the double bond, while the rest of thesecond styrene molecule adds to the second side of the doublebond. The product of this reaction still has a double bond.

Polystyrene. White atomsare hydrogen and black atoms

are carbon. Gray sticks indicatedouble bonds. Striped sticks

indicate benzene rings.P U B L I S H E R S R E S O U R C E G R O U P


POLYSTYRENE

So the reaction can be repeated a second time; and a thirdtime; and a fourth time; and so on. One goal of research onpolystyrene has been to determine how the size of the poly-styrene affects its properties (and, therefore, its uses) andhow to stop the polymerization reaction at some desiredpoint.

All that is needed to start the polymerization of styreneis a material that will cause the first double bond to break.Such materials are known as polymerization initiators. Oneof the most common initiators used in the polymerization ofstyrene is benzoyl peroxide (C6H5COOOCOC6H5). Once thepolymerization reaction begins, it tends to release enoughenergy for the reaction to continue on its own.

An especially popular form of polystyrene is known asexpanded polystyrene. It is made by blending air with moltenpolystyrene to make a lightweight foam sold under the tradename of Styrofoam�.


Polystyrene is the fourth largest thermoplastic poly-mer made in the United States by production volume. It

Interesting Facts

• Polystyrene is soldcommercially under morethan a hundred tradenames, the most famous ofwhich is probablyStyrofoam�.

• Only about 5 percent ofa styrofoam cup ispolystyrene. The rest is air.

• One of the innovative usesfor polystyrene is as abuilding material for theconstruction of newhouses. Scientists suggest

that it is perfect for thepurpose: lightweight,inexpensive, strong, a goodinsulator, and available allover the world. One of thefirst applicationssuggested for polystyreneas a building material isin the construction ofhouses in Afghanistan,where many families havelost their homes after twodecades of wars andearthquakes.


POLYSTYRENE

is used in the manufacture of hundreds of commercial,industrial, household, and personal articles. Some exam-ples include:

• Plastic model kits and toys;

• Containers with lids; disposable cups, plates, knives,forks, and spoons;

• ‘‘Jewel’’ cases for compact discs and cases for audiocas-settes;

• Plastic coat hangers and plastic trays;

• Refrigerator doors and air conditioner cases;

• Housing for machines; and

• Cabinets for clocks, radios, and television sets.

Some uses of expanded polystyrene include:

• In all kinds of containers to keep foods either hot orcold (such as ice chests);

• Egg cartons;

• Fillers in shipping containers;

• Packages for carry-out foods;

• Insulation for buildings;

• In the construction of boats; and

• For the construction of some types of furniture.

Polystyrene dust and powder formed during productioncan be a mild irritant to the eyes, skin, and respiratorysystem. But even for workers in the field, the risk isregarded as being very low. A more serious problem posedby the compound is the risk it poses for the environment.About half of all the polystyrene produced in the UnitedStates is used for packaging and ‘‘one-time use’’ purposes.That is, someone uses the product and then throws itaway. Since polystyrene does not readily decompose, ittends to accumulate in landfills and dumps. Some envir-onmentalists point out that large volumes of discardedpolystyrene contribute significantly to the nation’s solidwaste disposal problems. Industry spokespersons, however,point out that polystyrene accounts for less than onepercent of all solid wastes. In any case, a number ofindustries and companies have attempted to reduce theamount of polystyrene used in their products in order to


POLYSTYRENE

cut back on their contribution to the solid waste disposalproblem.


Boyd, Clark. ‘‘Polystyrene homes planned for Afghans.’’ BBC News.http://news.bbc.co.uk/2/hi/technology/3528716.stm (accessedon October 26, 2005).

‘‘Energy & Waste Landfilling.’’ Energy Information Administration, Department of Energy.http://www.eia.doe.gov/kids/energyfacts/saving/recycling/solidwaste/landfiller.html (accessed on October 26, 2005).

‘‘Polystyrene.’’ U.S. Environmental Protection Agency, EmissionsFactors and Policy Applications Center.http://www.epa.gov/ttn/chief/ap42/ch06/final/c06s06 3.pdf(accessed on October 26, 2005).

‘‘Polystyrene Packaging Delivers!’’ Polystyrene Packaging Council.http://www.polystyrene.org/ (accessed on October 26, 2005).

Sims, Judith. ‘‘Polystyrene.’’ In Environmental Encyclopedia. 3rded. Edited by Marci Bortman and Peter Brimblecombe.Detroit, Mich.: Gale, 2003.

See Also Styrene

Words to Know

HYDROCARBON a compound consisting ofcarbon and hydrogen.

POLYMER a compound consisting of verylarge molecules made of one or two smallrepeated units called monomers.

THERMOPLASTIC can be repeatedlysoftened and hardened by alternatelyheating and cooling.


POLYSTYRENE


FORMULA:-[-CF2-]-n

ELEMENTS:Carbon, fluorine


STATE:Solid


MELTING POINT:Varies; most common

range: 302�C–310�C(575�F–590�F)


SOLUBILITY:Insoluble in water,

concentrated acids,other inorganic

solvents and almostall organic solvents

Polytetrafluoro-ethylene

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OVERVIEW

Polytetrafluoroethylene (POL-ee-tet-ruh-FLUR-oh-ETH-eh-leen) is also known as polytetrafluoroethene, tetrafluoroethy-lene polymer, PTFE, and Teflon�. Polytetrafluoroethylenesare thermoplastic polymers made from the monomer tetra-fluoroethylene (CF2=CF2). A thermoplastic polymer is a materialthat can be repeatedly softened and hardened by alternatelyheating and cooling. The polytetrafluoroethylenes are wellknown by the trade name of Teflon� although they are alsoavailable under more than a hundred other trade names,including Aflon�, Algloflon�, Ethicon�, Fluon�, Ftorlon�,Halon�, Molykote�, Polyflon�, Polytef�, and PTFE�. DuPontChemical, one of the two largest manufacturers of polytetra-fluoroethylene, makes at least ten grades of Teflon�. Theseproducts differ from each other in the physical form inwhich they are provided (powders, aqueous dispersions,yarn, or film, for example) and size (molecular weight) of theproduct (ranging from low-molecular weight to high-molecularweight).

C

F

F

F

F

C

n


Polytetrafluoroethylene has the lowest coefficient offriction of any known substance. The coefficient of fric-tion is a measure of how easily one substance slides overthe surface of a second substance. Polytetrafluoroethy-lene’s low coefficient of friction means that nothing willstick very well to its surface, accounting for Teflon�’sprimary use in the manufacture of non-stick products.

Polytetrafluoroethylene was invented in 1938 by Roy J.Plunkett (1910–1994) quite by accident. As a researchchemist at DuPont’s Jackson Laboratory, Plunkett wasstudying compounds that might be used for refrigerants.He kept the compounds in steel tanks and was surprisedon one occasion to find that the gas he wanted did notleave the storage tank when the valve was opened. He cutthe tank open to see what had happened to the gas andfound a waxy white material. Upon analysis, the materialturned out to be polytetrafluoroethylene. The gas storedin the tank, the potential refrigerant, was tetrafluoroethy-lene. It had undergone polymerization spontaneouslywithin the tank, making it possible for Plunkett to dis-cover one of the most remarkable synthetic products inthe world.

Polytetrafluoroethylene.

Black atoms are carbon;turquoise atoms are fluorine.Gray stick indicates double


G R O U P


POLYTETRAFLUOROETHYLENE

HOW IT IS MADE

Molecules of tetrafluoroethylene contain double bonds.Any compound with double bonds has the ability to formpolymers. Polymerization of tetrafluoroethylene occurs whenthe double bond in one molecule breaks apart. A fluorineatom from a second molecule of the monomer then adds onto one end of the broken double bond. The rest of the secondmolecule adds to the other end of the broken double bond.A ‘‘double-molecule,’’ consisting of two monomers joinedto each other forms: CF2=CF2 + CF2=CF2 ! CF3CF2CF2=CF2.The product of this reaction also contains a double bond.So the process can be repeated to form another productconsisting of three monomer molecules: CF3CF2CF2=CF2 +CF2=CF2! CF3CF2CF2CF2CF2=CF2The process is repeated hun-dreds or thousands of times producing a long chain of mono-mers with the general formula -[-CF2-]-n.


Perhaps the best known application of polytetrafluor-oethylene is in kitchen utensils with non-stick coatings,such as pots, pans, and spatulas. Polytetrafluoroethylene isalso used to coat fibers to make them water-repellant andstain-resistant. Water will bead up and roll off the surface ofclothing and other materials coated with polytetrafluor-oethylene instead of penetrating the fabric and possibly

Interesting Facts

• Because Teflon� does notstick to anything else,cookware manufacturersmust use a special processto get it to stay on potsand pans. They sometimesbegin by blasting the panwith sand or grit toroughen the surface. Thenthey apply a special primer

that makes the Teflon�

adhere to the pan’ssurface.

• Teflon�’s non-stick qualityhas been compared totrying to make one pieceof ice stick to anotherpiece of ice.



leaving a stain. Polytetrafluoroethylene is available as aspray treatment for carpets and furniture, forming a mole-cular shield to prevent water or oil-based stains from pene-trating the material. Some carpets come pre-treated with apolytetrafluoroethylene product to keep them clean andfresh. The compound can also be used on wood and plasticflooring to protect it from dirt, stains, and moisure.

Automobile manufacturers used polytetrafluoroethylenein a variety of ways. Windshield wiper blades coated withpolytetrafluoroethylene are smoother and stronger thanuncoated blades. Automobile paint can be coated with poly-tetrafluoroethylene to protect a car’s finish from tree sap,insects, and other residues. Automobile upholstery is oftentreated with polytetrafluoroethylene to protect againststains caused by spilled drinks and dirty shoes. Polytetra-fluoroethylene added to oil makes it flow through an enginemore smoothly, reducing wear and tear on the engine.

Polytetrafluoroethylene is used widely for a number ofindustrial applications. Some armor-piercing bullets arecoated with the compound to reduce friction when the bulletleaves the gun barrel and increases the ease with which itbreaks through armor. Many electrical cables are insulatedwith polytetrafluoroethylene, which is not combustible orconductive. Food processing equipment made with polytetra-fluoroethylene is easier to clean and more efficient for cook-ing and baking than non-polytetrafluoroethylene equipment.Industrial bakers often use equipment coated with some typeof polytetrafluoroethylene. The product can also be used tocoat stainless steel, carbon steel, aluminum, steel alloys,brass, magnesium, glass, fiberglass, plastics, and rubber. Out-door signs are sometimes coated with polytetrafluoroethy-lene to make them last longer and resist stains.

Polytetrafluoroethylene has long been regarded as anessentially safe compound with no known health effects onhumans or experimental animals. Recently, questions havebeen raised about possible health hazards of one of thecompounds used in the manufacture of polytetrafluoroethy-lene, perfluorooctanoic acid (PFOA). Some studies suggestthat PFOA may be responsible for birth defects and thedevelopment of cancer in people who have been exposed tothe chemical. Other studies show that 96 percent of thechildren tested in 23 states and the District of Columbia in2001 had detectable levels of PFOA in their blood. Federal



agencies have not yet confirmed the level of risk that PFOAposes, if any, and have not listed any other chemicals used inthe manufacture of polytetrafluoroethylene as hazardous tohuman health.


‘‘PTFE Specifications.’’ Boedeker Plastics.http://www.boedeker.com/ptfe_p.htm (accessed on October 26,2005).

Summer, Chris. ‘‘Teflon’s Sticky Situation.’’ BBC News Online(October 7, 2004). Available online athttp://news.bbc.co.uk/1/hi/magazine/3697324.stm (accessedon October 26, 2005).

‘‘Technical Information: Teflon� Fluorocarbon Resin.’’ Omega.Stamford, Conn.: Omega Engineering, Inc. 2000. Availableonline athttp://www.omega.com/pdf/tubing/technical_section/teflon_ flourocarbon.asp (accessed on October 26, 2005).

‘‘Teflon (PTFE: polytetrafluoroethylene).’’ Fluoride Action Network.http://www.fluoridealert.org/pesticides/polytetrafluoroethylenpage.htm (accessed on October 26, 2005).

See Also Polyethylene

Words to Know


THERMOPLASTIC Able to be repeatedlysoftened and hardened by alternatelyheating and cooling.



OTHER NAMES:None

FORMULA:-[-CONH-C6H4-NCOO-

CH2CH2-O-]-n; otherstructures are possible


oxygen, nitrogen


STATE:Solid

MOLECULAR WEIGHT:Varies; very large

MELTING POINT:Variable



soluble in aromatichydrocarbons, such as

benzene and toluene

Polyurethane

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OVERVIEW

Polyurethanes (pol-ee-YUR-eth-anes) are a group of thermo-plastic polymers formed in the reaction between a diisocyanateand a polyol, an alcohol with two or more hydoxyl (-OH) groups.Diisocyanates are compounds that contain two isocyanate(-N=C=O) groups.

Polyurethanes are available in a variety of forms, includ-ing fibers, foams, coatings, and elastomers, rubber-like mate-rials. Each form of polyurethane has its own set of physicaland chemical properties. For example, fibers are moistureproof, stretchable, and resistant to the flow of electric cur-rent. Foams can be either rigid or flexible, with densities aslow as 32 kilograms per cubic meter (2 pounds per cubic foot)to as high as 800 kilograms per cubic meter (50 pounds percubic foot). They are excellent thermal (heat) insulators.Polyurethane coatings are hard, glossy, flexible, readily adhe-sive to other surfaces, and resistant to abrasion, weathering,and most inorganic chemicals. Elastomeric polyurethanes areresistant to abrasion, weathering, and most organic solvents.

n

C

O O

H

H

H

H

H

H

H

H

HH

N C C N C O C C O


With this variety of properties, polyurethanes have a verywide range of uses.

The basic process for making polyurethanes was firstdeveloped in 1937 by the German chemist Otto Bayer(1902–1982), who patented his discovery and founded acompany for its commercial production. The polyurethaneswere first put to widespread use during World War IIas substitutes for natural rubber in the manufacture oftires for military uses. The first rigid polyurethane foamwas made in 1940, again for military purposes; the firstpolyurethane adhesive, for the joining of rubber and glass,in 1941; and the first use of polyurethane as an insulator,in beer barrels, in 1948. Polyurethane fibers were alsoused during World War II for the manufacture of protec-tive clothing to be worn by soldiers in case of attacks bypoison gas. In the late 1950s, a stretchable material madeof polyurethane called spandex was introduced.

HOW IT IS MADE

Polyurethanes are formed by a reaction known as rear-rangement. In this reaction, a hydrogen atom from thepolyol (alcohol with two or more hydroxyl, -OH, groups)leaves the polyol and attaches itself to one of the nitrogenatoms in the diisocyanate molecule. The remnant of thepolyol left after the hydrogen atom leaves then attachesitself to the carbon atom next to the nitrogen that has justreceived the hydrogen. The end result of this reaction isthat two molecules, a diisocyanate molecule and a polyolmolecule, have joined to make a single molecule. But thatmolecule has the same general structure as the original

Polyurethane. Red atomsare oxygen; white atoms

are hydrogen; black atoms arecarbon; and blue atoms arenitrogen. Gray sticks showdouble bonds. P U B L I S H E R S



POLYURETHANE

reactants. So the reaction can be repeated with a seconddiisocyanate molecule and a second polyol molecule addingto the former product.

All that is needed to make this reaction happenis a suitable catalyst, a substance that will encouragethe first hydrogen atom to leave the polyol and move tothe diisocyanate. The catalyst most frequently used isdiazobicyclo[2.2.2]octane, more commonly known asDABCO. DABCO provides an initial ‘‘tug’’ on the hydrogenatom that needs to be moved. Once it gets the reactionstarted, DABCO has no further role and can be recoveredfor re-use.

Various forms of polyurethane are made by adding addi-tional steps to this fundamental process. For example, poly-urethane foams are made by adding water and carbon dioxideto the molten polymer. The carbon dioxide creates bubbles,which makes the mixture rise like bread and then hardeninto a foam. Flexible polyurethane for fibers and foam rub-ber can be made by adding polyethylene glycol, a softeningagent, to the mixture.


Flexible and rigid foams are the most popular types ofpolyurethane made in the United States. Flexible foamsare used for cushioning, as in mattresses, upholsteredfurniture, and automobile seats. Semiflexible foams arecomponent of carpet pads, sponges, packaging, and doorpanels for automobiles. Rigid polyurethane foams are usedto produce insulation for roofs, refrigerators, and freezers.The construction industry accounted for more than half ofall the rigid polyurethane foam made in 2002, primarily for

Interesting Facts

The U.S. polyurethane industry produced 2,915 millionkilograms (6,393 million

pounds) of polyurethanein 2002.


POLYURETHANE

roofing and wall insulation. The automotive industry wasthe second largest user of rigid foams, where polyurethanewas used for floor cushions, headliners, and heating andair-conditioning systems.

Polyurethane elastomers are flexible and strong. Theycan be stretched to a significant amount before returningto their original length. They are also shock absorbent. Theseproperties account for their uses in tires, shoe soles, skate-boards, and inline skates. Polyurethane elastomers can alsobe spun into fibers which are then used to make light,flexible clothing. Spandex, one of the most popular fabricsmade of polyurethane fibers, is both sturdy and flexible. It isused to make bathing suits and exercise clothing because itcan be distorted without losing its original shape or tearing.Polyurethane is also one of the main ingredients in thefabric known as pleather, or plastic leather. This syntheticform of leather is less expensive to produce and easier to dyethan real leather.

Polyurethane coatings are strong and durable. They can befound on surfaces that need to be flexible, abrasion resistant,and chemical resistant, such as dance floors and bowling alleys.Water-based coatings are often used on airplanes and othertransportation equipment. Polyurethane powder coatings arealso used on fluorescent lights, refrigerators, car wheels andtrim, lawnmowers, patio furniture, and ornamental iron.

Dust formed by the breakdown of polyurethane productsmay be an irritant to skin, eyes, and the respiratory system.No serious health problems have been associated with suchmaterials, however. Some of the raw materials used in themanufacture of the polyurethanes, such as the isocyanates,do pose health risks. These risks are of concern primarily toworkers who come into contact with those raw materials.

Words to Know

POLYMER a compound consisting of verylarge molecules made of one or two smallrepeated units called monomers.

THERMOPLASTIC capable of beingrepeatedly softened and hardened byalternately heating and cooling.


POLYURETHANE


Alliance for the Polyurethane Industry. ‘‘About Polyurethane’’http://www.polyurethane.org/about/(accessed on October 26,2005).

‘‘Making Polyurethanes.’’ Polymer Science Learning Center, University of Southern Mississippi.http://www.pslc.ws/mactest/uresyn.htm (accessed on October26, 2005).

‘‘Polyurethanes.’’ Huntsman.http://www.huntsman.com/pu/ (accessed on October 26, 2005).

Vartan, Starre. ‘‘Pretty in Plastic: Pleather Is a Versatile, thoughControversial, Alternative to Leather.’’ E (September October2002): 53 54.


POLYURETHANE


FORMULA:-[-CH2CHCl-]-n


chlorine


STATE:Solid


MELTING POINT:Decomposes at 148�C

(298�F)



soluble intetrahydrofuran,

dimethyllformamide,dimethylsulfoxide

Polyvinyl Chloride

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OVERVIEW

Polyvinyl chloride (pol-ee-VYE-nul KLOR-ide) is alsoknown as PVC, vinyl, chlorethylene homopolymer, and chlor-ethene homopolymer. It is the third most commonly producedplastic in the United States, exceeded only by polyethyleneand polypropylene. It is offered commercially in a varietyof formulations, usually as a white powder or colorless gran-ules. The compound is resistant to moisture, weathering,most acids, fats and oils, many organic solvents, and attackby fungi. It is easily colored and manufactured in a variety offorms, including sheets, films, fibers, and foam.

Polyvinyl chloride was first discovered accidentally in1835 by the French physicist and chemist Henry VictorRegnault (1810–1878). Regnault found that a container ofgaseous vinyl chloride (CH2CH=Cl) exposed to the sunlightgradually changed to a white powder. Regnault knew almostnothing about the composition of the powder or how it wasformed. Polyvinyl chloride remained a subject of little or nointerest to chemists for almost a century. German and

H H

H n

C

C

Cl


Russian chemists made some efforts to find useful applica-tions for the compound in the early twentieth century, with-out much success. The first patent for the production of thecompound was awarded to the German chemist FriedrichHeinrich August Klatte (dates not available) in 1913, butKlatte never marketed the product for commercial use.

Then, in 1926, Waldo Lonsbury Semon (1898–1999), achemist at B. F. Goodrich, rediscovered polyvinyl chloride,once again by accident. Semon had been assigned the task atGoodrich of finding a substitute for natural rubber as a liningfor metal tanks and for finding a material that would bond therubber substitute to the metal tank. One of the materials hestudied was polyvinyl chloride. In his work, Semon did not somuch rediscover polyvinyl chloride as to find new ways ofworking with the material. For example, he found that hecould dissolve the compound in various organic solvents, con-verting them so that they could be molded, extruded, andformed. He also discovered that he could control the propertiesof the material by altering the amount of solvent used todissolve powdered polyvinyl chloride.

Poly(vinyl chloride). Whiteatoms are hydrogen, black

atoms are carbon and greenatom is chlorine. Gray stick

represents a double bond.P U B L I S H E R S R E S O U R C E G R O U P


POLYVINYL CHLORIDE

Goodrich adapted Semon’s discovery for two specificapplications: shoe heels and the coating on chemical racks.Those applications were not profitable enough for Goodrichto continue making polyvinyl chloride. But Semon continuedto look for new ways of adapting the compound for additionalapplications. He was eventually successful and by 1931 thecompany had begun to turn out a full line of polyvinylchloride products in most of the forms currently available.

HOW IT IS MADE

Polyvinyl chloride is made by polymerizing vinyl chlor-ide (CH2=CHCl). Polymerization occurs when the double bondin vinyl chloride breaks, allowing one molecule of vinylchloride to combine with a second molecule of vinyl chloride:CH2=CHCl + CH2=CHCl ! CH3CHClCH=CHCl. The product ofthat reaction also contains a double bond, allowing the reac-tion to be repeated: CH3CHClCH=CHCl + CH2=CHCl !CH3CHClCH2CHClCH=CHCl. Once again, the final product con-tains a double bond, and the reaction can be repeated againand again and again. The reaction is made possible by usingsome agent to cause double bonds to break. In the originalexperiments carried out by Regnault, Klatte, and others, thatagent was sunlight. Chemists have long since learned, how-ever, that a variety of chemicals known as peroxide initiatorsare more effective at breaking double bonds. Peroxide initia-tors are compounds with an oxygen-oxygen bond (–O–O–). Oneof the most widely used initiators is benzoyl peroxide(C6H5CO-O-O-C6H5CO).

Interesting Facts

• The recycling symbol forpolyvinyl chloride is thenumber 3 inside a trianglemade of three arrows.

• The environmental groupGreenpeace has called fora global ban on the

production of polyvinylchloride because the toxicsubstance dioxin isreleased (albeit, in verysmall amounts) as abyproduct of thecompound’s production.


POLYVINYL CHLORIDE


An estimated 7 billion kilograms (15.7 billion pounds) ofpolyvinyl chloride were produced in the United States in2006. It is available in more than 50 trade names, includingAirex, Armodour, Astralon, Benvic, Bonloid, Chemosol,Chlorostop, Dacovin, Dorlyl, Flocor, Lucoflex, Norvinyl, Opa-lon, Polivinit, Polytherm, Sicron, Takilon, Vinikulon, Vini-plast, and Wilt Pruf. About three-quarters of that amountwas made in a rigid format that is hard and inflexible. Theremaining one-quarter was made in a flexible form, producedby adding materials to polyvinyl chloride that make it softand pliable. About 75 percent of all rigid polyvinyl chloride(half of all the compound made in the United States) goes tothe construction industry. It has replaced older buildingmaterials such as clay, concrete, and wood because it isinexpensive, lightweight, resistant to damage by the sun,and easy to assemble. The compound is used to make vinylsiding, windows, plumbing pipes, flooring, electric cables,roofing materials, and insulation for cables and wires.

Flexible polyvinyl chloride is used to make fibers andfilms for applications such as clothing, upholstery, plasticbottles, medical equipment, lightweight toys, shower cur-tains, and packaging films. Some of the medical equipmentproduced from polyvinyl chloride include bags to hold bloodand other fluids, artificial heart valves, and tubes used inkidney dialysis. Medical products made from polyvinyl chlor-ide are strong enough to be air-dropped to troops in combatzones. Automobile manufacturers use polyvinyl chloride inbody side moldings, interior upholstery, engine wiring, floormats, adhesives, dashboards, arm rests, and coatings underthe vehicle.

The commercial and household products containing poly-vinyl chloride are generally regarded as posing no threat tohuman health. However, a number of questions have beenraised about possible health hazards and risks to the environ-ment as a result of the process by which polyvinyl chloride ismade, some of its applications, and its eventually disposal. Forexample, polyvinyl chloride is made from vinyl chloride, whichitself is toxic and a carcinogen. People who work with vinylchloride in production facilities are at risk for developing aform of liver cancer that may be related to exposure to vinylchloride. Vinyl chloride, in turn, is made from chloride, a verytoxic gas that poses health risks to people who work with it.


POLYVINYL CHLORIDE

Some environmental health experts point out that pro-ducts made of polyvinyl chloride may give off toxic or carci-nogenic gases for short periods of time after they have beenput into use. For example, shower curtains and automobileupholstery containing polyvinyl chlorides may release hazar-dous chemicals into the air for a few months after they arefirst installed.

Some concern has also been expressed about additives usedwith polyvinyl chloride. For example, some of the substancesused to soften the compound belong to a family known as thephthalates, which are known carcinogens with toxic effects.Some health experts point out that infants may ingest smallamounts of phthalates from PVC toys they chew on.

Finally, the disposal and destruction of compounds con-taining polyvinyl chloride may create environmental pro-blems. Burning such products, for example, releases hydro-gen chloride gas, a suffocating and toxic gas, into theatmosphere. Enough concern about the health and environ-mental hazards has arisen that some governmental bodies inEurope have placed limitations on the uses to which PVCproducts can be put.


‘‘Healthy Building Network.’’http://www.healthybuilding.net/ (accessed on October 29,2005).

Meikle, Jeffrey L. American Plastic: A Cultural History. Piscataway, N.J.: Rutgers University Press, 1997.

Thornton, Joe. ‘‘Environmental Impacts of Polyvinyl Chloride(PVC) Building Materials.’’ A briefing paper for the U.S. GreenBuilding Council, n.d. Available online athttp://www.usgbc.org/Docs/LEED_tsac/PVC/CMPBS%20Original%20Submittal.pdf (accessed on October 29,2005).

‘‘Vinyl The Material.’’ The Vinyl Institute.http://www.vinylinfo.org/materialvinyl/history.html (accessedon October 29, 2005).


POLYVINYL CHLORIDE

OTHER NAMES:Potassium acid car-

bonate; potassiumhydrogen carbonate

FORMULA:KHCO3

ELEMENTS:Potassium, hydrogen,

carbon, oxygen

COMPOUND TYPE:Acid salt (inorganic)

STATE:Solid


MELTING POINT:decomposes above

100�C (212�F)



insoluble in ethylalcohol

PotassiumBicarbonate

KE

YF

AC

TS

OVERVIEW

Potassium bicarbonate (poe-TAS-ee-yum buy-KAR-bo-nate)is a colorless crystalline solid or white powder with no odor anda salty taste. It occurs naturally in salt beds, sea water, silicaterocks, and a number of foods, primarily fruits and vegetables.Potassium bicarbonate is also present in the tissues of humansand other animals, where it is involved in a number of essentialbiological processes, including digestion, muscle contraction,and heartbeat. It is used primarily in cooking and baking, as afood additive, and in fire extinguishers.

HOW IT IS MADE

Potassium bicarbonate is made by passing carbon diox-ide gas through an aqueous solution of potassium carbonate:K2CO3 + CO2 + H2O ! 2KHCO3


One of the most familiar applications of potassium bicar-bonate is as an antacid to treat the symptoms of upset stomach.The compound reacts with stomach acid—hydrochloric acid;

O

CK+ O- OH


HCl—to relieve gaseous distress, stomach pain, and heartburn.The compound can also be used to treat potassium deficiencyin the body. Some research suggests that potassium bicarbo-nate may help restore muscle and bone tissue, particularly inwomen with the degenerative bone disease osteoporosis. Thecompound is also used as a food additive, as a leavening agent,to maintain proper acidity in foods, to supply potassium to adiet, and to provide the bubble and fizz in carbonated drinks.

Potassium bicarbonate is also used in certain types offire extinguishers. When such an extinguisher is used, thepotassium bicarbonate reacts with an acid present in thedevice to produce carbon dioxide. The carbon dioxide pro-pels a liquid from the extinguisher and, itself, helps putout a fire. Potassium bicarbonate is also used in agricul-ture to maintain proper acidity in soils and to supplypotassium that may be missing from the ground.

Under normal circumstances, potassium bicarbonateposes no health threat to humans. Excess potassium in thebody may result in a condition known as hyperkalemia,characterized by tingling of the hands and feet, muscle weak-ness, and temporary paralysis. Such a condition is very rarewhen potassium bicarbonate is used in normal amounts.

Potassium bicarbonate. Redatoms are oxygen, white atom

is hydrogen; black atom iscarbon; and turquoise atom is

potassium. Gray stick indicatesdouble bond. P U B L I S H E R S



POTASSIUM BICARBONATE


‘‘Potassium Bicarbonate.’’ Yale New Haven Health Drug Guide.http://yalenewhavenhealth.org/library/healthguide/en us/drugguide/topic.asp?hwid=d03600a1 (accessed on October 31,2005).

‘‘Potassium Bicarbonate Handbook.’’ Armand Products Company.Available online athttp://www.oxy.com/OXYCHEM/Products/potassium_bicarbonates/literature/Po0tBiVs6.pdf (accessed on October 31, 2005).

Rowley, Brian. ‘‘Fizzle or Sizzle? Potassium Bicarbonate CouldHelp Spare Muscle and Bone.’’ Muscle & Fitness (December2002): 72.

‘‘Strong Muscle and Bones.’’ Prevention (June 1, 1995): 70 73.

See Also Sodium Bicarbonate

Interesting Facts

Potassium bicarbonate canbe substituted for bakingsoda (sodium bicarbonate;

NaHCO3) for people who areon a low sodium diet.


POTASSIUM BICARBONATE

OTHER NAMES:Potassium hydrogen

sulfate; potassiumacid sulfate

FORMULA:KHSO4


sulfur, oxygen


STATE:Solid


MELTING POINT:about 200�C (about400�F); decomposes



decomposes in alcohol

Potassium Bisulfate

KE

YF

AC

TS

OVERVIEW

Potassium bisulfate (poe-TAS-ee-yum BYE-sul-fate) isan odorless white crystalline solid that begins to decom-pose at its melting point. It is deliquescent, meaning that

has such a strong tendency to absorb moisture from the airthat it becomes wet and dissolves in the water it has

absorbed.

HOW IT IS MADE

Potassium bisulfate is typically made by heating potas-

sium sulfate (K2SO4) with sulfuric acid. The acid provides thehydrogen needed to convert the salt (K2SO4) to the corre-

sponding acid salt (KHSO4).


Potassium bisulfate is used as a food additive. The com-

pound is listed on the U.S. Food and Drug Administration’s

S

O O

OHO-

K+


list of Generally Regarded as Safe (GRAS) list. The list

contains chemicals thought to be safe for human consump-tion even though they have not been tested. Potassium

bisulfate is used in foods as a preservative because itinterferes with the growth of insects, bacteria, and fungithat cause foods to spoil. It is also used as a leavening

agent in cake mixes. One of its most important uses is inthe wine industry, where it is used to convert certain

compounds that occur naturally in grapes into potassiumbitartrate. Potassium bisulfate is also used as a flux, in the

analysis of ores and silica compounds, in the manufactureof fertilizers, and in the preparation of methyl and ethyl

acetate.

Potassium bisulfate is a strong irritant to human tissue.If spilled on the skin, inhaled, or ingested, it can burn tissue

causing skin rashes, sore nasal passages, irritation of thethroat, and damage to the eyes. Burns of the mouth and

stomach may also occur. These hazards are of concern pri-marily to people who work directly with the compound and

do not pose a threat as a food additive.

Potassium bisulfate. Redatoms are oxygen; white atom

is hydrogen; yellow atom issulfur; and turquoise atom is

potassium. Gray sticks indicatedouble bonds. P U B L I S H E R S



POTASSIUM BISULFATE


‘‘Agency Response Letter: GRAS Notice No. GRN 000060.’’ U.S.Food and Drug Administration.http://www.cfsan.fda.gov/~rdb/opa g060.html (accessed onNovember 1, 2005).

‘‘Safety (MSDS) data for potassium bisulfate .’’ Physical and Theoretical Chemistry Laboratory, University of Oxford.http://ptcl.chem.ox.ac.uk/MSDS/PO/potassium_bisulfate.html(accessed on November 1, 2005).

Words to Know

DELIQUESCENT having a strong tendency toabsorb moisture from the air, so that itbecomes wet and dissolves in the water ithas absorbed.

FLUX a material that lowers the meltingpoint of another substance or mixtureof substances or that is used in cleaninga metal.


POTASSIUM BISULFATE

OTHER NAMES:Potassium hydrogen

tartrate; potassiumacid tartrate; cream

of tartar

FORMULA:KHC4H4O6


carbon, oxygen

COMPOUND TYPE:Salt (acid salt);

inorganic

STATE:Solid


MELTING POINT:Not available

BOILING POINT:Not available

SOLUBILITY:Somewhat soluble

in cold water; verysoluble in hot water;

insoluble in alcohol

Potassium Bitartrate

KE

YF

AC

TS

OVERVIEW

Potassium bitartrate (poe-TAS-ee-yum bye-TAR-trate) is acolorless crystalline or white powdery solid with a pleasant,slightly acidic taste. The compound is a by-product of thefermentation of grape juice and, as such, may have been knownto humans for as long as seven thousand years. An article in thejournal Nature reported some years ago that traces of thecalcium salt of tartaric acid, a cousin of potassium bitartrate,was found in remnants of a pottery jar in northern Iran datingto about 7,000 BCE. Potassium bitartrate was used by ancientpeople in a wide range of household uses, from cooking andbaking to cleaning. The true chemical nature of the substancelong known as cream of tartar was determined in 1770 bythe Swedish chemist Karl Wilhelm Scheele (1742–1786).

HOW IT IS MADE

Potassium bitartrate is made today by the process thathas been used for centuries. Wine lees (the solid material left

C CC

H

HO C

HO

OH

OH

O

K+ –O


after grapes have been crushed to make wine) are treatedwith hot water, which dissolves the potassium bitartrate. Thehot solution is then allowed to evaporate. As potassium bitar-trate crystals form, they are removed and purified.


The primary use of potassium bitartrate is in commercialfood production and household cooking and baking. Thecompound is added to foods to stabilize egg whites after theyhave been beaten, to add body to a product, and to producecreamier textures for sugar-based foods. A small amount ofpotassium bitartrate also adds a pleasantly acidic taste tofoods. The compound is found most commonly in baked goods,candies, crackers, confections, gelatins, puddings, jams andjellies, soft drinks, margarines, and frostings. Some of thefunctions that potassium bitartrate performs in foods include:

• It acts as a leavening agent, causing a product to rise, inbaked goods;

• It serves as an anticaking agent and stabilizer tothicken some food products;

Potassium bitartrate. Redatoms are oxygen; white atomsare hydrogen; black atoms are

carbon; and blue atom ispotassium. Gray sticks indicate




POTASSIUM BITARTRATE

• It prevents the crystallization of sugars when makingcandy and sugary syrups;

• It hides the harsh aftertaste and intensifies the flavorsof some foods; and

• It improves the color of vegetables that have beenboiled during preparation.

Potassium bitartrate also has a number of other uses. Itcan be used as a laxative for both humans and domesticanimals. It is used in the processing of some metals, givinga colored tinge to the final product. The compound is also aningredient in products used to clean brass, copper, aluminum,and other metals. And it is used in the chemical industry as araw material for the preparation of other tartrate com-pounds.

There are no known health hazards for potassium bitar-trate except for the general overall caution given in theIntroduction that all chemicals in some concentrations canpose a hazard. Potassium bitartrate is thought to be one ofthe safest chemical compounds for general use.


‘‘Potassium Bitartrate.’’ ChemicalLand21.com.http://www.chemicalland21.com/arokorhi/lifescience/foco/POTASSIUM%20BITARTRATE.htm (accessed on October 29,2005).

‘‘Potassium Bitartrate.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/p5565.htm(accessed on October 29, 2005).


POTASSIUM BITARTRATE


FORMULA:K2CO3

ELEMENTS:Potassium, carbon,

oxygen


STATE:Solid







Potassium Carbonate

KE

YF

AC

TS

OVERVIEW

Potassium carbonate (poe-TAS-ee-yum KAR-bun-ate) isalso known as potash, pearl ash, salt of tartar, carbonate ofpotash, and salt of wormwood. It is a white, translucent,odorless, granular powder or crystalline material that tendsto absorb water from the air. As it does, it is converted intothe sesquihydrate (‘‘sesqui’’ = one-and-a-half) with the formulaK2CO3�1.5H2O. That formula means that three molecules ofpotassium carbonate share two molecules of water among them.

Potash is easily produced by pouring water over theashes of burned plants and then evaporating the solutionformed in large pots (hence the name: ‘‘pot’’ ‘‘ash’’). The pro-cess has been known since at least the sixth century CE andthe resulting product used in the manufacture of soap.Potash was one of the first chemicals to be exported byAmerican colonists, with shipments having left Jamestownas early as 1608. Potassium carbonate is also called pearl ashand salt of tartar, both of which are impure forms of thecompound. The impurities present include sodium chloride

O

C O

K+

K+

O

2–


and some heavy metals (such as iron and lead). The primaryuses of potassium carbonate are in the production of fertili-zers, soaps, and heat-resistant glass.

HOW IT IS MADE

Most of the potassium carbonate made in the UnitedStates is produced beginning with potassium chloride (KCl)obtained from seven mines in New Mexico, Michigan, andUtah. The potassium chloride is first converted to potassiumhydroxide (KOH) by electrolysis. The potassium hydroxide isthen treated with carbon dioxide (CO2) to obtain potassiumbicarbonate (KHCO3). Finally, the potassium bicarbonate isdecomposed by heating, yielding water, carbon dioxide, andpotassium carbonate.

Another method of preparation, called the Engel-Prechtprocess, is a modification of this procedure. A mixture ofpotassium chloride, magnesium carbonate or magnesiumoxide, and carbon dioxide is treated under 30 atmospheres

Potassium carbonate. Redatoms are oxygen; black atomis carbon; and turquoise atoms

are potassium. Gray stickindicates a double bond.



POTASSIUM CARBONATE

of pressure, with the formation of a double salt, KHCO3�Mg-CO3�4H2O. The double salt is then heated to obtain potassiumcarbonate. The traditional method of obtaining potash fromwood and vegetable ash is now obsolete.


An estimated 7 million metric tons (6.5 million shorttons) of potassium carbonate were produced in the UnitedStates in 2005. Of that amount, nearly 90 percent was usedfor the production of fertilizers. Potash provides plants withthe potassium they need to stay healthy and grow. Potassiumis one of the three major nutrients required by plants, theother two being nitrogen and phosphorus. The next largestapplication for potassium carbonate is in the chemical indus-try, where it is used as a raw material to make other chemicalcompounds, potassium silicate being the most common.

Smaller amounts of potassium carbonate are still usedfor what was once its major application: the manufacture ofsoap. Potassium soaps (made from potassium carbonate) have

Interesting Facts

• The first patent everissued in the United Stateswas awarded in 1790 toSamuel Hopkins for a newand better way of makingpearl ash.

• Pearl ash was used in theUnited States in theeighteenth century as aleavening agent in thebaking of bread.

• The demand for potashbegan to fall off in the lateeighteenth century asimproved methods for thesynthesis of sodium

carbonate were developed.Sodium carbonate canreplace potassiumcarbonate in manyapplications.

• The term potash hashistorically had manydifferent meanings. It hasbeen used to refer topotassium hydroxide (KOH),potassium chloride (KCl),potassium sulfate (K2SO4),potassium nitrate (KNO3),or to some combination ofthese compounds.


POTASSIUM CARBONATE

some characteristics different from more common sodiumsoaps (made from sodium carbonate). They tend to be softeror even liquid and better able to create suds in water thatcontains a high concentration of minerals. Potassium carbo-nate is also used to make specialty glasses, such as televisionscreens, cathode ray tubes, and optical lenses. Some otheruses of the compound include:

• For glazes in the making of pottery;

• In the manufacture of pigments and printing inks;

• As an additive in certain food products, chocolate beingone example;

• For the tanning and finishing of leather and the dyeing,washing, and finishing of wool; and

• As a flux in metal working.

Potassium carbonate in dry or dissolved form is anirritant to the eyes, skin, and respiratory system. It can causeinflammation of the skin, eyes, throat, and stomach. Potas-sium carbonate’s action is caused by its caustic properties inwater solution, which are produced when it is dissolved inwater or when it is absorbed by moist tissues in the body.


‘‘International Potash Institute.’’http://www.ipipotash.org/index.php (accessed on October 31,2005).

‘‘The Potash Trade.’’ Townships Heritage WebMagazine.http://www.townshipsheritage.com/Eng/Hist/Life/potash.html (accessed on October 31, 2005).

Words to Know

CAUSTIC Strongly basic or alkaline; canirritate or corrode living tissue.

ELECTROLYSIS Process in which an electriccurrent is used to bring about chemicalchanges.

FLUX A material that lowers the meltingpoint of another substance or mixture ofsubstances or that is used in cleaning ametal.


POTASSIUM CARBONATE

‘‘Potassium Carbonate.’’ Chemical Land 21.http://www.chemicalland21.com/arokorhi/industrialchem/inorganic/POTASSIUM%20CARBONATE.htm(accessedon October 31, 2005).

‘‘Potassium Carbonate.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/p5609.htm(accessed on October 31, 2005).

Willett, Jason C. ‘‘Potash.’’ U.S. Geological Survey CommodityStatistics and Information. Available online athttp://minerals.usgs.gov/minerals/pubs/commodity/potash/potasmyb04.pdf (accessed on October 31, 2005).

See Also Potassium Chloride; Potassium Hydroxide


POTASSIUM CARBONATE

OTHER NAMES:Potassium muriate;

muriate of potash

FORMULA:KCl

ELEMENTS:Potassium, chlorine

COMPOUND TYPE:Binary salt(inorganic)

STATE:Solid



BOILING POINT:Not applicable; sub-

limes at about 1500�C(2700�F)


slightly soluble inethyl alcohol, andinsoluble in ether,

acetone, and otherorganic solvents

Potassium Chloride

KE

YF

AC

TS

OVERVIEW

Potassium chloride (poe-TAS-ee-yum KLOR-ide) occurs asa white or colorless crystalline solid or powder. It is odorless,but has a strong saline (salty) taste. It occurs naturally in theminerals sylvite, carnallite, kainite, and sylvinite. It alsooccurs in sea water at a concentration of about 0.076 percent(grams per milliliter of solution). Potassium chloride is themost abundant compound of the element potassium and hasthe greatest number of applications of any salt of potassium.By far the most important application of potassium chlorideis in the manufacture of fertilizers.

HOW IT IS MADE

All of the major sources of potassium chloride have theirorigin in sea water. Sea water is a solution of a number ofsalts dissolved in water. The most important of those saltsare sodium chloride (about 2.3 percent), magnesium chloride(about 0.5 percent), sodium sulfate (about 0.4 percent),

Cl- K+


calcium chloride (about 0.1 percent) and potassium chloride(about 0.07 percent). When large bodies of sea water dry up,they leave behind complex mixtures of minerals consistingof these salts. Over millions of years, huge deposits of theseminerals have been buried under the land. In the UnitedStates, sea salt deposits are found in New Mexico, Texas,California, and Michigan.

Any one of the salts present in a sea salt deposit—includ-ing potassium chloride—can be extracted by a common pro-cedure. The minerals that make up the deposit are crushedand dissolved in hot water. The solution is then allowed tocool very slowly. As it cools, each of the dissolved saltscrystallizes out at a specific temperature, is removed fromthe solution, and is purified. Since potassium chloride ismuch more soluble in hot water than in cold water, it crystal-lizes out after other salts have been removed.

The majority of potassium chloride in the United Statesis now extracted by a lengthy process that also begins withthe crushing of natural ores, such as sylvite and carnalite.The solid mixture is then cleaned and purified before beingtreated with a flotation agent, usually some type of amine.A flotation agent is a material that coats the desired com-pound, such as potassium chloride, and allows it to float tothe surface of the reaction chamber, like the soap suds thatfloat on top of a washing machine. An amine is an organiccompound that contains the nitrogen, usually as the -NH2

Potassium chloride. Turquoiseatom is potassium and greenatom is chlorine. Potassiumatom is positively charged.Chlorine atom is negatively

charged. P U B L I S H E R S



POTASSIUM CHLORIDE

group. The amine-coated potassium chloride is skimmed offthe top of the reaction mixture, purified, and prepared insome crystalline or powder form.


Potassium chloride is present in some foods in smallamounts. The compound is also used as a food additive toincrease the acidity and to stabilize, thicken, or soften somefood products, such as jams and jellies and preserves that areartificially sweetened. Many infant formulas also containpotassium chloride. Potassium chloride is also used as anutrient for yeast cultures and in making beer. The com-pound is used as a salt substitute for people who are onlow-salt (meaning low-sodium) diets. Some brand names ofthese products are LoSalt�, Reheis Less Salt Blend�, andMorton� Lite Salt�.

The largest application of potassium chloride is in theproduction of fertilizers. More than ninety percent of thepotassium chloride produced in the United States is usedfor that purpose. The compound provides the potassiumplants need to stay healthy and grow normally. It is one ofthree macronutrients—substances needed in relatively largeamounts—for normal growth. The other two macronutrientsare phosphorus and nitrogen. Smaller amounts of potassiumchloride are used in the production of other potassiumcompounds, in photography, and in chemical research appli-cations.

Interesting Facts

• One use of potassiumchloride is as a lethalinjection for prisoners whohave been given the deathpenalty. The chemicalinterferes with normalheart function and causesa heart attack within five

to about eighteen minutesafter injection. Thirty-fourof the United Statesprescribe death by lethalinjection for prisoners whohave been convicted ofmurder.


POTASSIUM CHLORIDE


Benfell, Carol. ‘‘Routine but Deadly Drug: Potassium Chloride Has aJekyll and Hyde Personality. ’ American Iatrogenic Association.http://www.iatrogenic.org/potchlor.html (accessed on October31, 2005).

‘‘Potassium Chloride.’’ MedicineNet.com.http://www.medicinenet.com/potassium_chloride/article.htm(accessed on October 31, 2005).

‘‘Potassium Chloride.’’ University of Maryland Medical Center.http://www.umm.edu/altmed/ConsDrugs/PotassiumChloridecd.html (accessed on October 31, 2005).

See Also Potassium Carbonate; Potassium Hydroxide;Potassium Nitrate; Sodium Chloride


POTASSIUM CHLORIDE

OTHER NAMES:Potassium mono-

fluoride

FORMULA:KF

ELEMENTS:Potassium, fluorine

COMPOUND TYPE:Binary salt (inor-

ganic)

STATE:Solid


MELTING POINT:858�C(1580�F)

BOILING POINT:1502�C(2736�F)


very soluble in hotwater; insoluble in

ethyl alcohol; solublein hydrofluoric acid

(H2F2)

Potassium Fluoride

KE

YF

AC

TS

OVERVIEW

Potassium fluoride (poe-TAS-ee-yum FLU-ride) is a color-less or white crystalline or powdery compound with no odor,but a sharp, salty taste. It has somewhat limited uses inindustry and chemical research.

HOW IT IS MADE

In one method for making potassium fluoride, potassiumcarbonate (K2CO3) is dissolved in hydrofluoric acid, resultingin the formation of potassium bifluoride (KHF2): K2CO3 +2H2F2 ! 2KHF2 + CO2 + H2O. The potassium bifluoride isthen heated to form potassium fluoride and hydrogen fluor-ide: KHF2 ! KF + HF.

Potassium fluoride can also be prepared by the directreaction between hydrofluoric acid and potassium hydroxide:H2F2 + 2KOH ! 2KF + 2H2O. The potassium fluoride thusformed is then dried and crystallized or converted to powderform.

K+ F-



Potassium fluoride is used as a fluoridating agent—asubstance that provides fluorine atoms to other com-pounds—in the preparation of organic chemicals. It also findssome use in the field of metallurgy, where it is used as a flux,to finish metals, to make coatings for metals, and in tin

Potassium fluoride. Silveratom is potassium; yellow atom

is fluorine. P U B L I S H E R S


Interesting Facts

• In France, potassium fluor-ide is sometimes added totable salt to help preventdental cavities.

• Potassium fluoride cannot be shipped out of theUnited States to other

countries without a speciallicense from the U.S.Department of Commercebecause the compound isan important raw materialin the manufacture ofcertain chemical weapons.


POTASSIUM FLUORIDE

plating. Potassium fluoride is used to frost and etch glass, asin the manufacture of some optical glasses, and to makeinsecticides, pesticides, and disinfectants.

Potassium fluoride is irritating to the skin, eyes, andrespiratory system. It is moderately toxic by ingestion, caus-ing nausea, vomiting, diarrhea, and stomach pains. In largerdoses, it can cause damage to the brain, kidneys, and heart.Long-term exposure to potassium fluoride can cause damageto the teeth and bones. One condition that can develop iscalled fluorosis. Symptoms of the condition include brittlebones, weight loss, anemia, hardening of the ligaments, andstiffness of the joints.


Hernandez, Lucula Pazos. ‘‘Prevention of Dental Caries ThroughSalt Fluoridation in Mexico.’’http://www.ibiblio.org/taft/cedros/english/newsletter/n3/prevent.html (accessed on October 31, 2005).

‘‘Potassium Fluoride.’’ Patnaik, Pradyot. Handbook of Inorganic

Chemicals. New York: McGraw Hill, 2003, 754 755.

‘‘Potassium Fluoride, Anhydrous.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/p5774.htm (accessedon October 31, 2005).

‘‘Silver Production on the Moon.’’ The Artemis Project.http://asi.org/adb/02/13/02/silicon production.html (accessedon October 31, 2005).

Words to Know

FLUX A material that lowers the meltingpoint of another substance or mixtureof substances or that is used in cleaninga metal.

METALLURGY The study of the propertiesand structures of metals.


POTASSIUM FLUORIDE

OTHER NAMES:Caustic potash;

potash lye; potassa;potassium hydrate

FORMULA:KOH

ELEMENTS:Potassium, oxygen,

hydrogen

COMPOUND TYPE:Base (inorganic)

STATE:Solid





ethyl alcohol, methylalcohol, and glycerol

Potassium Hydroxide

KE

YF

AC

TS

OVERVIEW

Potassium hydroxide (poe-TAS-ee-yum hy-DROK-side) is awhite deliquescent solid that is available in sticks, lumps,flakes, or pellets. A deliquescent material is one that tends toabsorb so much moisture from the atmosphere that it becomesvery wet, even to the point of dissolving in the water it hasabsorbed. Potassium hydroxide also absorbs carbon dioxidefrom the air, changing in the process to potassium carbonate(K2CO3). Potassium hydroxide is one of the most caustic materi-als known. It has a number of uses in industry and agriculture.

Potassium hydroxide is chemically very active. It reactsviolently with acids, generating significant amounts of heatin the process. In moist air, it corrodes metals such as tin,lead, zinc, and aluminum with the release of combustible andexplosive hydrogen gas.

HOW IT IS MADE

Potassium hydroxide is made by the electrolysis of anaqueous solution of potassium chloride (KCl). In that process,

OH–

K+


an electric current decomposes potassium chloride intopotassium and chlorine. The chlorine escapes as a gaseousby-product and the potassium reacts with water to formpotassium hydroxide.


An estimate 440,000 metric tons (485,000 short tons) ofpotassium hydroxide were used in the United States in 2005.About 53 percent of that amount was used in the productionof other potassium compounds, especially potassium carbo-nate (28 percent), potassium acetate, potassium cyanide, potas-sium permanganate, and potassium citrate. About 10 percentof all caustic potash was used in the manufacture of potassiumsoaps and detergents. Most soaps and detergents are made ofsodium hydroxide. But potassium hydroxide can be substi-tuted for sodium hydroxide to obtain soaps and detergentswith special properties. Liquid soaps and soaps that will latherin salt water or water with a high mineral content are exam-ples of such specialized potassium soaps.

Some other applications of potassium hydroxide include:

• The manufacture of liquid fertilizers, herbicides, andother agricultural chemicals;

• As a neutralizing agent in many chemical and indus-trial processes;

• In the production of synthetic rubber;

Potassium hydroxide. Redatom is oxygen; white atom ishydrogen; and turquoise atom

is potassium. P U B L I S H E R S



POTASSIUM HYDROXIDE

• In the food production industry, where it is used in theremoval of peels from fruits and vegetables, the carme-lization of products that contain sugar, the thickeningof ice cream, the softening of olives, the production ofchocolate and cocoa, and the preparation of hominyfrom corn kernels;

• In the manufacture of alkaline storage batteries andsome types of fuel cells;

• In the refining of petroleum;

• As a way for removing horn buds from young cattle;

• In a number of cosmetic procedures, such as softeningof cuticles, removal of warts, and cleaning of dentures;and

• As an ingredient in paint removers.

Potassium hydroxide is a very hazardous chemical. It iscorrosive to tissue and can cause severe burns of the skin,eyes, and mucous membranes. If ingested, it can cause inter-nal bleeding, scarring of tissue, nausea, vomiting, diarrhea,and lowered blood pressure that can result in a person’scollapse. In sufficient amounts, it can cause death. Inhalationof potassium hydroxide fumes or dust can cause lung irrita-tion, sneezing, sore throat, runny nose, and severe damage tothe lungs. In contact with the eyes, the compound can causeblurred vision and, in sufficient amounts, loss of eyesight.People who have to work with the compound should alwayswear goggles, gloves, and protective clothing to reduce theirrisk of contact with the chemical.

Interesting Facts

• Pure potassium hydroxideis difficult to preparesince the compound isso reactive that it tendsto react with moisture,carbon dioxide, and otherimpurities with which itcomes into contact. The

compound is commerciallyavailable in a purity ofabout 90 percent. Muchpurer products are avail-able, however, whenneeded.


POTASSIUM HYDROXIDE


‘‘Caustic Potash.’’ Occidental Petroleum Corporation.http://www.oxy.com/OXYCHEM/Products/caustic_potash/caustic_potash.htm (accessed on November 1, 2005).

Cavitch, Susan Miller. The Natural Soap Book: Making Herbal andVegetable Based Soaps. Markahm, Canada: Storey Publishing,1995.

‘‘Potassium Hydroxide.’’ Medline Plus.http://www.nlm.nih.gov/medlineplus/ency/article/002482.htm (accessed on November 1, 2005).

‘‘Potassium Hydroxide.’’ NIOSH Pocket Guide to Chemical Hazards.http://www.cdc.gov/niosh/npg/npgd0523.html (accessed onNovember 1, 2005).

See Also Sodium Hydroxide

Words to Know

AQUEOUS SOLUTION A solution thatconsists of some material dissolved in water.

CAUSTIC Strongly basic or alkaline; able toirritate or corrode living tissue.

DELIQUESCENT Having the tendency to absorbmoisture and, therefore, dissolve or melt.



POTASSIUM HYDROXIDE

FORMULA:KI

ELEMENTS:Potassium, iodine


ganic)

STATE:Solid





ethyl alcohol, acet-one, and glycerol

Potassium Iodide

KE

YF

AC

TS

OVERVIEW

Potassium iodide (poe-TAS-ee-yum EYE-oh-dide) is awhite crystalline, granular, or powdered solid with a strong,bitter, salty taste. It is used as a feed additive, a dietarysupplement, in photographic films, and in chemical research.

HOW IT IS MADE

A number of methods are available for the preparation ofpotassium iodide. In one procedure, elemental iodine (I2) isadded to a solution of potassium hydroxide (KOH): I2 + 6KOH! 5KI + KIO3 + 3H2O. The potassium iodide formed is sepa-rated from the potassium iodate (KIO3) by fractional crystal-lization. That is, the solution is warmed and then cooled. Asthe temperature falls, the two compounds, potassium iodideand potassium iodate, crystalize out at different tempera-tures and can be separated from each other. The potassiumiodate can then be heated, causing it to decompose and makeadditional potassium iodide: 2KIO3 ! 2KI + 3O2.

K+I-


Potassium iodide can also be produced by reactinghydriodic acid (HI) with potassium bicarbonate: HI + KHCO3

! KI + CO2 + H2O.

Finally, the compound can be made by reacting iron (III)iodide with potassium carbonate (K2CO3): Fe3I8 + 4K2CO3 !8KI + 4CO2 + Fe3O4.


Potassium iodide is added to animal feeds to ensure thatdomestic animals get the iodine they need in their dailydiets. A mixture of iodine in aqueous potassium iodide calledSSKI has long been used as a disinfectant. The active agentin this mixture is iodine, and the potassium iodide is addedto increase the iodine’s solubility in water. SSKI is used topurify small amounts of water, to clear up pimples, to pre-vent sinus infections, and to treat bladder, lung, and stomachinfections.

Perhaps the best known use of potassium iodide today isas a treatment for radiation exposure. When a nuclear bombexplodes or a nuclear accident occurs, one of the most danger-ous products released to the environment is a radioactiveisotope known as iodine-131. Iodine-131 enters the human bodyand travels to the thyroid, where it attacks cells and tissues,eventually resulting in thyroid cancer. Experts recommendthat people exposed to radiation take potassium iodide as aprotection against this hazard. The potassium iodide saturates

Potassium iodide. Green atomis iodine and turquoise atom is

potassium. P U B L I S H E R S



POTASSIUM IODIDE

the thyroid gland, making it difficult for the gland to absorbradioactive iodine that may enter the body.

Potassium iodide is also used in the production of photo-graphic film and in a number of chemical tests, such as thedetermination of dissolved oxygen in water and the presenceof starch in an unknown mixture.

Under most circumstances, there are no health hazardsassociated with potassium iodide. Taking an excess of thecompound may have harmful effects on the thyroid gland,however. For that reason, people with an overactive thyroidshould not take potassium iodide unless so directed bytheir doctors. Also, a person should not take potassiumiodide as a preventative treatment against radiation. Itprovides no protection in advance of radiation exposureand, in excessive amounts, can create problems of its ownfor the thyroid.

Interesting Facts

• Iodized salt contains asmall amount of potassiumiodide. The potassiumiodide is added to ensurethat people get enoughiodine in their daily diet.A deficiency of iodineresults in a medical condi-tion known as goiter, alarge swelling in the neck.

Before iodized salt wasavailable, many peoplefailed to get enough iodinein their diets and goiterwas a very common healthproblem.

• Potassium iodide occursnaturally in seaweed.

Words to Know

RADIOACTIVE ISOTOPE A form of an ele-ment that gives off some form of radia-tion and changes into another element.


POTASSIUM IODIDE


‘‘Frequently Asked Questions on Potassium Iodide (KI).’’ U.S. Foodand Drug Administration.http://www.fda.gov/cder/drugprepare/KI_Q&A.htm (accessedon November 1, 2005).

‘‘Potassium Iodide.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/p5906.htm(accessed on November 1, 2005).

‘‘Potassium Iodide (Systemic).’’ Medline Plus.http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202472.html (accessed on November 1, 2005).

Wright, Jonathan V. ‘‘One Mineral Can Help a Myriad of Conditions from Atherosclerosis to ‘COPD’ to Zits.’’ Tahoma Clinic.http://www.tahoma clinic.com/iodide.shtml (accessed onNovember 1, 2005).

See Also Silver Iodide


POTASSIUM IODIDE

OTHER NAMES:Niter; saltpeter;

nitrate of potash

FORMULA:KNO3

ELEMENTS:Potassium, nitrogen,

oxygen


STATE:Solid





SOLUBILITY:Soluble in water

and glycerol;slightly soluble in

ethyl alcohol

Potassium Nitrate

KE

YF

AC

TS

OVERVIEW

Potassium nitrate (poe-TAS-ee-yum NYE-trate) is trans-parent, colorless, or white, and may be crystalline or powderysolid. It is odorless with a sharp, cool, salty taste. It is slightlyhygroscopic, that is, having a tendency to absorb moisturefrom the air. Potassium nitrate, more commonly known assaltpeter or niter, has been used by humans for many cen-turies. Going back as far as ancient Chinese civilizations, thecompound was used as an ingredient in fireworks, to pre-serve foods, to make incense burn more evenly, to increasethe male sex drive, and for magic potions.

HOW IT IS MADE

Potassium nitrate is made commercially by reactingpotassium chloride (KCl) with nitric acid (HNO3) at hightemperatures: 3KCl + 4HNO3 ! 3KNO3 + Cl2 + NOCl + 2H2O.

The compound can also be obtained for use from naturalsources. It occurs as a thin, whitish, glassy crust on rocks in

O

K+O–

NO


sheltered areas, such as caves. In warm climates, potassiumnitrate forms when bacteria decompose animal feces andother organic matter. The compound usually appears as awhite powder on the surface of soil. These sources of potas-sium nitrate are of use on a small scale basis and have nocommercial value.


The primary use of potassium nitrate is in explosives,blasting powders, gunpowder, fireworks, and matches. Thecompound is used as an oxidizing agent in such preparations.An oxidizing agent is a substance that provides oxygen forthe combustion of some other material. For example, gun-powder, the oldest known explosive, is a mixture of potas-sium nitrate, charcoal (nearly pure carbon), and sulfur. Whenthe mixture is ignited, the carbon and sulfur burn veryrapidly to produce carbon dioxide (CO) and sulfur dioxide(SO2. At the same time, the potassium nitrate decomposesto produce a variety of products, one of which is nitric oxide(NO). The rapid formation of very hot gases is responsible forthe shock wave produced in the explosion.

Potassium nitrate. Red atomsare oxygen; blue atom is

nitrogen; and turquoise atom ispotassium. P U B L I S H E R S



POTASSIUM NITRATE

Some other uses of potassium nitrate include:

• As a meat preservative that helps meats retain theirbright red color;

• As a flux for soldering;

• In fertilizers, especially for use with crops such astomatoes, potatoes, tobacco, leafy vegetables, citrusfruits, and peaches;

• In the manufacture of glasses and ceramics;

• As an additive for tobacco products that helps thetobacco burn more cleanly and smoothly;

• As an oxidizing agent in rocket propulsion systems;

• As a diuretic, a substance that increases the flow ofurine from the body; and

• As a raw material in the manufacture of other potas-sium compounds.

Exposure to moderate amounts of potassium nitrate dustand fumes can result in irritation of the skin, eyes, andrespiratory system. Symptoms may include sneezing, coughing,

Interesting Facts

• At one time, potassiumnitrate was prepared bymixing manure with mor-tar or wood ash, soil, andan organic material, suchas straw. The bed was keptmoist with urine andturned often to speeddecomposition of theorganic matter. After ayear, the bed was thor-oughly watered, dissolvingthe potassium nitrate thathad accumulated. It wasthen recrystallized andpurified.

• In 1862, leaders of theConfederate Army ordereda chemistry professor atSouth Carolina College toteach farmers how to makepotassium nitrate toensure an adequate supplyof the compound for use inmaking gunpowder.

• Gunpowder was probablyfirst used as early as theeleventh century. The Eng-lish natural philosopherRoger Bacon (1214–1294)described a method formaking gunpowder in 1242.


POTASSIUM NITRATE

dizziness, drowsiness, and headache. Ingestion of the com-pound may result in nausea, vomiting, and severe abdominalpain. Exposure to large quantities of the compound may havemore serious consequences because it interferes with theblood’s ability to transport oxygen. In such cases, a personmay experience shortness of breath, bluish skin, seriousdamage to the kidneys, unconsciousness, and even death.People who work directly with potassium nitrate are at great-est risk for such health problems.


‘‘Material Safety Data Sheet: Potassium Nitrate.’’ Department ofChemistry, Iowa State University.http://avogadro.chem.iastate.edu/MSDS/KNO3.htm (accessedon November 3, 2005).

Multhauf, Robert P., and Christine M. Roane. ‘‘Nitrates.’’ In Dic

tionary of American History. Edited by Stanley I. Kutler. 3rded., vol. 6. New York: Charles Scribner’s Sons, 2003.

‘‘Potassium Nitrate.’’ Hazardous Substances Data Bank.http://toxnet.nlm.nih.gov/cgi bin/sis/search/r?dbs+hsdb:@term+@na+Potassium+Nitrate (accessed onNovember 3, 2005).

‘‘Potassium Nitrate.’’ International Chemical Safety Cards.http://www.inchem.org/documents/icsc/icsc/eics0184.htm(accessed on November 3, 2005).

‘‘Potassium Nitrate.’’ Skylighter.http://www.skylighter.com/potassium nitrate.html (accessedon November 3, 2005).

Words to Know

FLUX A material that lowers the meltingpoint of another substance or mixture of

substances or that is used in cleaning ametal.


POTASSIUM NITRATE


FORMULA:K2SO4

ELEMENTS:Potassium, sulfur,

oxygen


STATE:Solid



BOILING POINT:Vaporizes at 1689�C

(3072�F)


slightly soluble inglycerol; insoluble in

ethyl alcohol, acet-one, and most other

organic solvents

Potassium Sulfate

KE

YF

AC

TS

OVERVIEW

Potassium sulfate (poe-TAS-ee-yum SUL-fate) is alsoknown as potash of sulfur, sulfuric acid dipotassium salt,arcanum duplicatum, and sal polychrestum. It is a colorlessor white granular, crystalline, or powdery solid with a bitter,salty taste. It occurs in nature as the mineral arcanite and inthe mineral langbeinite (K2Mg2(SO4)3). The compound wasknown to alchemists as early as the fourteenth century, andwas analyzed by a number of early chemists, includingJohann Glauber (1604–1670), Robert Boyle (1627–1691), andOtto Tachenius (c. 1620–1690).

HOW IT IS MADE

A variety of methods for preparing potassium sulfate isavailable. In one process, the compound is extracted from themineral langeinite by crushing and washing the mineral andthen separating out the double salt, K2Mg2(SO4)3. The pro-duct is then treated with an aqueous solution of potassium

S

O O

K+ K+

OO 2–


chloride (KCl) to separate the two parts of the double saltfrom each other: K2Mg2(SO4)3 + 4KCl! 3K2SO4 + 2MgCl2.Thecompound can also be produced synthetically by treatingpotassium chloride with sulfuric acid (H2SO4): 2KCl + H2SO4

! K2SO4 + 2HCl.

In a variation of this procedure, potassium chloride istreated with the raw materials from which sulfuric acid ismade, rather than the acid itself: 4KCl + 2SO2 + 2H2O + O2 !2K2SO4 + 4HCl.


Over 90 percent of the potassium sulfate produced in theUnited States is used as a fertilizer. It provides plants withtwo essential elements: potassium and sulfur. It finds itsgreatest use on crops that are sensitive to the chloride ion(Cl-) present in most conventional agricultural fertilizers.Those crops include coffee, tea, tobacco, citrus fruits, grapes,and potatoes. However, its use is somewhat limited because itis twice as expensive as fertilizers that contain potassiumchloride.

Potassium sulfate. Red atomsare oxygen; yellow atom is

sulfur; and turquoise atomsare potassium. P U B L I S H E R S



POTASSIUM SULFATE

The second most important use of potassium sulfate is asa supplement for animal feeds, accounting for another 8percent of the compound produced in the United States.The remaining 1 percent of potassium sulfate goes to theproduction of gypsum board and gypsum cement, for thesynthesis of potassium alum (potassium aluminum sulfate),in the manufacturing of glass and ceramics, for the produc-tion of dyes and lubricants, and as a flash suppressant inexplosives. A flash suppressent is, as its name suggests, achemical that reduces the amount of flash produced when anexplosive is detonated.

Exposure to moderate amounts of potassium sulfateappears to have no serious effects on human health.Ingestion of large amounts of the compound, can causesevere gastrointestinal irritation that requires medicalattention.

Interesting Facts

Potassium sulfate, sodiumsulfate, and their doublesalts with calcium andmagnesium occur naturallyin salt lakes and in volcanic

lava. At one time and onsome uncommon occasionstoday potassium sulfatewas obtained from salt lakesources.

Words to Know

AQUEOUS SOLUTION A solution that con-sists of some material dissolved in water.


from simple beginning chemicals, or reac-tants.


POTASSIUM SULFATE


‘‘Potassium Sulfate.’’ Hummel Croton, Inc.http://www.hummelcroton.com/msds/k2so4_m.html (accessedon November 3, 2005).

‘‘Potassium Sulfate.’’ International Programme on ChemicalSafety.http://www.inchem.org/documents/icsc/icsc/eics1451.htm(accessed on November 3, 2005).

‘‘Potassium Sulfate.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/p6137.htm(accessed on November 3, 2005).

See Also Potassium Carbonate, Potassium Chloride,Potassium Nitrate


POTASSIUM SULFATE

FORMULA:C3H8



hydrocarbon; organic

STATE:Gas



(�323.73�F)




benzene

Propane

KE

YF

AC

TS

OVERVIEW

Propane (PRO-pane) is a colorless gas with an odor ofnatural gas. It occurs naturally in petroleum and naturalgas. It belongs to the alkane family of organic compounds,compounds consisting of only carbon and hydrogen, alljoined by single bonds. Propane is commonly sold as fuel,often available in a liquefied form known as liquid propanegas, or LPG.

HOW IT IS MADE

Propane is most widely available as a component ofpetroleum and natural gas, fossil fuels that formed manymillions of years ago when marine organisms died, sank tothe bottom of seas, and were eventually buried under massivelayers of debris. The decay of those organisms without accessto oxygen resulted in the formation of so-called fossil fuels:natural gas, petroleum, and coal. All fossil fuels are complexmixture of some free carbon and a very large variety of

C

H

H

H3C CH3


hydrocarbons. Natural gas, for example, consists primarily ofmethane, ethane, and propane.

Roughly half of all the propane produced in the UnitedStates comes from petroleum gases produced during therefining of crude oil and half from natural gas. The mixture

Propane . White atoms arehydrogen; black atoms are




PROPANE

of gases from either refined petroleum or natural gas is lique-fied and then allowed to boil off, changing back to the originalgases. Each gas boils off at its characteristic boiling point andcan be captured and removed as it escapes from the liquidmixture. Often, propane is allowed to remain in its liquid stateand is then made available as liquid propane gas (LPG). LPG iseasier to store and transport than is gaseous propane.


About 100 billion liters (27 billion gallons) of propanewere produced in the United States in 2004. The largestportion of that output (45 percent) was used for space heat-ing, water heating, the operation of appliances, and otherpurposes in commercial and residential buildings. Propanehas many advantages as a fuel:

• It produces less pollution than gasoline or coal.

• Propane water heaters are less expensive to purchaseand operate than are electric water heaters, and theycan heat more water than electric heaters.

• Propane fireplaces are less expensive and less pollutingthan wood-burning fireplaces, and they can be turnedon and off with a switch.

• Many professional cooks prefer propane stoves to elec-tric stoves because they heat instantly and are easier tocontrol.

• Propane dryers take three-quarters of the time of elec-tric dryers to dry the same amount of clothes.

• Propane appliances continue to operate during poweroutages, unlike electric appliances.

Interesting Facts

Propane’s natural odor is sofaint that it can often notbe detected when leaksoccur. To avoid the problemof unexpected fires and

explosions, manufacturersusually add a compoundwith a strong odor, such asethanediol, to make leaksmore noticeable.


PROPANE

The second most important application of propane is in thepetrochemical industry where the compound is used for theproduction of a host of organic chemicals, primarily ethyleneand propylene. Ethylene and propylene are two important com-pounds used in the production of plastics and other kinds ofpolymers. They ranked third and sixth on the list of the largestvolume chemicals produced in the United States in 2004.

Farm use and industrial use follow next in importance,each accounting for about 7 percent of the propane used in theUnited States each year. On farms, propane is used to operatefarm equipment and irrigation systems, to dry crops, and tohelp control weeds. In industries, the compound is used forspace heating, for soldering, for cutting and treating metals,and as a fuel for fork lifts. Finally, a relatively small amount ofpropane is used as a fuel for cars, trucks, and other vehicles.Many people argue that more vehicles should be built tooperate on propane because the gas produces fewer pollutants,reduces wear and tear on engines, and burns more efficientlythan gasoline. So far, however, propane-powered vehicles havenot become very popular in the United States. In the early2000s, there were about 350,000 propane-powered vehicles inthe United States and about 4 million in the world.

In moderate amounts, propane presents no healthhazards to humans. In larger quantities, it may have a narco-tic effect, producing drowsiness, disorientation, headaches,and confusion. The gas is both flammable and explosive andrequires special care when being used.


‘‘Facts about Propane.’’ National Propane Gas Association.http://www.npga.org/files/public/Facts_About_Propane.pdf(accessed on November 3, 2005).

Words to Know

ALKANE One of a family of organic com-pounds consisting of only carbon andhydrogen, all joined by single bonds.



PROPANE

‘‘Propane.’’ Air Liquide.http://www.airliquide.com/en/business/products/gases/gasdata/index.asp?GasID=53 (accessed on November 3, 2005).

‘‘Propane Education and Research Council.’’http://www.propanecouncil.org/ (accessed on November 3,2005).

‘‘Propane: Exceptional Energy.’’http://www.usepropane.com (accessed on November 3, 2005).

‘‘Propane: What is Propane?’’ Vehicle Buyer’s Guide for Consumers.http://www.eere.energy.gov/cleancities/vbg/consumers/lpg.shtml (accessed on November 3, 2005).

Sherman, Josepha, and Steve Brick. Fossil Fuel Power. Mankato,Minn.: Capstone Press, 2003.

See Also Ethylene; Methane; Propylene


PROPANE

OTHER NAMES:Propene; methylethy-

lene; methylethene

FORMULA:CH2=CHCH3


COMPOUND TYPE:Alkene; unsaturated


STATE:Gas



(�301.43�F)



water; very soluble inethyl alcohol and

ether

Propylene

KE

YF

AC

TS

OVERVIEW

Propylene (PRO-puh-leen) is a colorless gas with aslightly sweet odor that burns with a yellow, sooty flame. Itranks sixth among all chemicals produced in the UnitedStates and second (after ethylene) among all organics. Itsprimary use is in the manufacture of polypropylene, one ofthe most popular polymers produced in the world.

HOW IT IS MADE

Propylene is prepared commercially by the thermal orcatalytic cracking of hydrocarbons. The term cracking refersto a process by which large hydrocarbons—organic com-pounds that contain only carbon and hydrogen—are brokendown into smaller hydrocarbons. Cracking can be accom-plished either by exposing the hydrocarbons to high tem-peratures, a process called thermal cracking, or by using acatalyst, a process called catalytic cracking. A catalyst is amaterial that increases the rate of a chemical reaction without

CCH3C

H

HH


undergoing any change in its own chemical structure. Ther-mal cracking is also known as steam cracking becausesteam is used to produce the high temperatures need tobring about the cracking reactions. Propylene can also beprepared by the catalytic dehydrogenation of propane(C3H8). Catalytic dehydrogenation is a process by whichhydrogen atoms are removed from a substance, resultingin the formation of double bonds where single bonds pre-viously existed.

Propylene. White atoms arehydrogen and black atoms arecarbon. Gray sticks indicatedouble bonds. P U B L I S H E R S



PROPYLENE


About 15.3 million metric tons (16.8 million short tons)

of propylene were produced for commercial sale in the UnitedStates in 2004. About 39 percent of that amount was used forthe production of polypropylene. Almost all of the remaining

production was also used for the synthesis of chemical com-pounds, especially acrylonitrile (14 percent), propylene oxide

(11 percent), cumene (10 percent), oxo alcohols (8 percent),isopropyl alcohol (7 percent), oligomers (5 percent) and

acrylic acid (3 percent). Acrylonitrile, propylene oxide, oxoalcohols, and acrylic acids are all used primarily for the

production of various types of polymers. Cumene is itselfused as a raw material in the production of other organiccompounds, especially acetone and phenol.

In addition to the propylene produced for commercial

uses, large amounts of the gas are retained by the petroleumindustry for conversion to products that are added to gaso-

line and other petroleum-based products. According to someestimates, between half and three-quarters of all propylenethat comes from cracking reactions is retained for this pur-

pose, leaving the remainder for commercial sale.

In addition to the hazard it poses as a flammable gas,propylene does have some health risks. At relatively high

concentrations, it can act as an asphyxiant, a substance thatcan produce unconsciousness, and can cause death. It can also

act as a mild anesthetic.

Interesting Facts

• Plants emit smallamounts of propylene gasnaturally.

• Small amounts ofpropylene are alsoproduced when organic

matter burns and isfound in products suchas cigarette smoke,automobile exhaust, andburning leaves.


PROPYLENE


‘‘Chronic Toxicity Summary: Propylene.’’ California Office ofEnvironmental Health Hazard Assessment.http://www.oehha.org/air/chronic_rels/pdf/115071.pdf(accessed on November 3, 2005).

Meikle, Jeffrey L. American Plastic: A Cultural History. Piscataway, NJ: Rutgers University Press, 1997.

‘‘Propylene.’’ Equistar Chemical Company.http://www.equistarchem.com/html/petrochemical/olefins/propylene.htm (accessed on November 3, 2005).

‘‘Propylene.’’ LG Petrochemical.http://www.lgpetro.com/eng/product_info/product/propylene.html (accessed on November 3, 2005).

See Also Ethylene; Polypropylene

Words to Know




PROPYLENE


FORMULA:CH3C5HN(OH)(-

CH2OH)2


nitrogen, oxygen


STATE:Solid


MELTING POINT:159�C–162�C (318�F–

324�F)

BOILING POINT:Not applicable; sub-limes above melting

point


slightly soluble inethyl alcohol and

acetone

Pyridoxine

KE

YF

AC

TS

OVERVIEW

Pyridoxine (peer-ih-DOCK-seen) is also known as 3-Hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridine; 3-hydroxy-4,5-dime-thylol-2-methylpyridine; and vitamin B6. It is a white, odorless,crystalline compound with a slightly bitter taste. The termpyridoxine is also used as a generic term for three compoundswith biological activity classified under the term VitaminB6. The three compounds are pyridoxine, pyridoxal, andpyridoxamine. Pyridoxine is usually produced commerciallyas the hydrochloride, CH3C5HN(OH)(CH2OH)2�HCl, which hassomewhat different physical characteristics from pyridoxineitself.

Vitamin B6 was discovered in 1938 by five groups ofresearchers working independently. The five groups wereall looking for a cure for a disease in rats called acrodyniathat resembles the human disease pellagra. In the early1930s, the Hungarian-American biochemist Albert Szent-Gyorgi (1893–1986) hypothesized the existence of a vitaminthat would cure acryodynia and even gave the vitamin a

CC

CH

HC

H

H

N H

CHO

OH

OH

C CH3C


name, vitamin B6. So the simultaneous discovery of such acompound in 1938 was not much of a surprise.

The first component of vitamin B6, pyridoxine, was firstsynthesized, also in 1938, by the Austrian-German chemistRichard Kuhn (1900–1967). Its chemical structure was deter-mined a year later by American chemists Karl August Folkers(1906–1997) and S. A. Harris (dates not available) at the

Pyridoxin. Red atoms areoxygen; white atoms

are hydrogen; black atoms arecarbon; and blue atom is

nitrogen. Ring of alternatingwhite and dark sticks is abenzene ring. P U B L I S H E R S



PYRIDOXINE

Merck chemical corporation. Pyridoxine is the most stableform of the vitamin, so it is the form used in vitaminsupplements and as a food additive.

HOW IT IS MADE

Pyridoxine is produced naturally by most plants andanimals in sufficient amounts to prevent vitamin B6 defi-ciency diseases. It is also produced synthetically by a com-plex series of reactions that begins with isoquinoline(C9H7N).


Vitamin B6 has been shown to be essential in manybiochemical reactions that occur in plants and animals.Although it may occur in any one of the three forms listedabove, the compound usually acts as the phosphate ester,pyridoxine phosphate. Pyridoxine phosphate functions as acoenzyme in the transformation of amino acids, the buildingblocks from which proteins are made. A coenzyme is a che-mical compound that works with an enzyme to catalyze someessential chemical reaction in the body. Pyridoxine phos-phate appears to be necessary for the synthesis of proteinsfrom amino acids as well as the metabolism of amino acids toproduce energy needed for normal body functioning.

Vitamin B6 deficiency diseases are very rare. In 1954, abatch of commercially prepared baby food was overheatedduring its preparation. Overheating apparently destroyed thevitamin B6 present in the food. Babies who were fed with thefood had convulsions became unusually irritable, and devel-oped unusual behaviors. As soon as the babies were givenvitamin B6 supplements, these symptoms disappeared. Suchinstances among humans are so rare that they become the

Interesting Facts

Because pyridoxine is watersoluble, it dissolves when

foods are cooked or processed.


PYRIDOXINE

subject of articles in medical journals. Other reportedinstances of vitamin B6 deficiency disease have involvedpregnant women who did not receive enough of the vitaminin their daily diets and people living in Cuba during the early1990s who had restricted diets. Symptoms of vitamin B6

deficiency include general weakness, anemia, cracked lips,inflamed tongue and mouth, irritability, depression, and skindisorders.

Meats have the highest concentration of vitamin B6, sovegetarians may be at risk for deficiency disorders. Otherfoods that contain high concentrations of the vitamininclude bananas, mangoes, avocados, and potatoes. Increaseddoses of vitamin B6 are sometimes used to treat morningsickness and insomnia, and some authorities recommend thevitamin to decrease the risk of heart disease. The maximumrecommended dose of vitamin B6 is 50 milligrams a day.



‘‘Dietary Supplement Fact Sheet: Vitamin B6.’’ NIH Office of Dietary Supplements.http://ods.od.nih.gov/factsheets/vitaminb6.asp (accessed onNovember 3, 2005).

Turner, Judith. ‘‘Pyridoxine.’’ In Gale Encyclopedia of Alternative

Medicine. Detroit: Gale Group, 2004.

Words to Know


METABOLISM The process including all ofthe chemical reactions that occur in cellsby which fats, carbohydrates, and other

compounds are broken down to produceenergy and the compounds needed tobuild new cells and tissues.



PYRIDOXINE

OTHER NAMES:Vitamin A

FORMULA:C20H30O


oxygen


STATE:Solid




decomposes

SOLUBILITY:Practically insolublein water; soluble in

ethyl alcohol andmethyl alcohol

Retinol

KE

YF

AC

TS

OVERVIEW

Retinol (RET-uh-nol) is the scientific name for vitamin A,a vitamin found only in animals. It occurs as a yellowish toorange powder with a slight brownish cast and is a relativelystable compound. Retinol is converted in the body from analcohol to the corresponding aldehyde, retinal (C20H28O), oneof the primary chemical compounds involved in the processby which light is converted to nerve impulses in the retina ofthe eye. Vitamin A is also required for a number of otherbiochemical reactions in the body, including growth anddevelopment of tissue and maintenance of the immune sys-tem.

HOW IT IS MADE

Vitamin A is synthesized in animal bodies through avariety of pathways. One important source of vitamin A is agroup of related compounds called the carotenes, substancesresponsible for the yellowish or orangish appearance of

C C C C

CC C

C C C C

H

H H H H

CH3

CH3

H3CCH3 CH3

C CC C OH

H

H

H

H

H

HHH


fruits and vegetables such as carrots, sweet potatoes, squash,cantaloupe, apricots, pumpkin, and mangos. Some leafygreen vegetables, such as collard greens, spinach, and kale,are also good sources of the carotenes. The most important ofthe carotenes is b-carotene (beta-carotene), C40H56. The oxida-tion of carotenes in animal bodies converts them to retinol.

The chemical structure of retinol was determined in 1931by Swiss chemist Paul Karrer (1889–1971), and the compound

Retinol. Red atom is oxygen;white atoms are hydrogen; andblack atoms are carbon. Graysticks indicate double bonds.


RETINOL


was first prepared synthetically shortly thereafter by Aus-trian-German chemist Richard Kuhn (1900–1967). The firstsuccessful process for producing retinol commercially wasdeveloped in the mid-1940s by German chemist Otto Isler(1920–1992), then employed at the pharmaceutical companyRoche, located in Sissein, Germany. Isler’s process involved acomplex series of reactions that begins with the combinationof a fourteen carbon hydrocarbon and a six carbon hydro-carbon to create the fundamental backbone from which theretinol molecule is constructed. Regular production of vita-min A began in 1948 with a projected output of 10 kilogramsper month, which before long was raised to 50 kilograms permonth. The Roche plant at Sissein continues to produceretinol today.


Vitamin A is probably best known for its role in main-taining normal vision. Deficiencies of the compound arelikely to manifest themselves earliest in a variety of eyeproblems, most commonly night blindness. Night blindnessis a condition in which one loses the ability to distinguishobjects in reduced light. If left untreated, vitamin A deficien-cies may lead to decreased ability to see in normal light and,eventually, to complete blindness.

But vitamin A has been shown to have a number of otherfunctions in the body. It is essential for the maintenance ofgrowth, bone formation, reproduction, proper immune sys-tem function, and healing of wounds. A number of additionalclaims have been made for the compound, although evidenceis not as strong as it is for the above functions. For example,

Interesting Facts

• Animals that live in verycold climates have highconcentrations of retinolin their livers. A polar bearliver contains enoughretinol to kill a human

who eats it.VitaminA deficiency is theleading cause ofchildhood blindness inthe world today.


RETINOL

it may be effective in preventing or treating a variety ofconditions such as measles, intestinal parasites, osteoporosis,inflammatory bowel disease, bone marrow disorders, certaintypes of cancer, tuberculosis, peritonitis, osteoarthritis, foodpoisoning, Alzheimer’s disease, miscarriage, and HIV/AIDS.In each of these cases, evidence is not yet strong enough toshow a clear-cut connection between retinol and disease, butresearch is being conducted to determine how strong theassociation may be.

Retinol is available commercially in a variety of formula-tions, including tablets, capsules, and creams. Such productsusually contain a modified form of retinol that is more easilyabsorbed by the body. For example, a product known astretinoin is a synthetic form of retinol known as all-transretinoic acid. The term all trans means that all of the doublebonds in retinoic acid are located on the same side of themolecule. Products containing tretinoin are used to treatacne, pimples, wrinkles, blackheads, freckles, sun-spots, andeven pre-cancerous lesions. They work by increasing the ratewith which the skin sheds old cells and replaces them withnew cells.

Vitamin A supplements in pill or capsule form are avail-able in two formulations, those that contain retinol andthose that contain beta carotene. It is not possible to taketoo much of the latter type of vitamin A. The body will notconvert excess amounts of carotene into retinol but will,instead, excrete the excess in the urine or stool. An excessof retinol-based vitamin A, by contrast, may result in cer-tain medical problems. Since the vitamin is fat soluble, inmay be stored in body fat and reach relatively high concen-trations if too much is ingested. An excess of retinol in thebody may be associated with liver damage, osteoporosis,rash, fatigue, bone and joint pain, nausea, insomnia, andpersonality changes.


Powers, Jennifer I. ‘‘Acne Medication.’’ In Chemistry: Foundations

and Applications. Volume 1. Edited by J. J. Lagowski. NewYork: Macmillan Reference USA, 2004, 12 15.

‘‘Vitamin A.’’ Bristol University School of Chemistry.http://www.chm.bris.ac.uk/webprojects2002/schnepp/vitamina.html (accessed on November 3, 2005).

RETINOL


‘‘Vitamin A (Retinol).’’ Hypertexts for Biomedical Sciences.http://arbl.cvmbs.colostate.edu/hbooks/pathphys/misc_topics/vitamina.html (accessed on November 3, 2005).

‘‘Vitamin A (Retinol).’’ University of Maryland Medical Center.http://www.umm.edu/altmed/ConsSupplements/VitaminARetinolcs.html (accessed on November 3, 2005).

See Also Beta-Carotene


RETINOL

OTHER NAMES:Vitamin B2

FORMULA:C17H20N4O6


nitrogen, oxygen


STATE:Solid




decomposes


in water and ethylalcohol; very solublein alkaline solvents,

but resulting indecomposition

Riboflavin

KE

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OVERVIEW

Riboflavin (REY-bo-FLAY-vin), commonly known as vita-min B2, is an orange-yellow crystalline solvent with a bittertaste. It is relatively stable when exposed to heat, but tendsto decompose in the presence of light for extended periods oftime. Riboflavin is used in the body for a variety of func-tions, including the metabolism of carbohydrates for theproduction of energy and the production of red blood cells.

Riboflavin was first observed in 1879 by the Englishchemist Alexander Wynter Blyth (1844-1921) who noticed acompound in cow’s milk that glowed with a yellow fluores-cence when exposed to light. Blyth called the compoundlachtochrome (lachto- = ‘‘milk’’ and -chrome = color), but wasunable to determine its chemical composition or its chemi-cal properties. In fact, it was not until the 1930s that thechemical nature of the compound was determined. TheSwiss chemist Paul Karrer (1889–1971) and the Austrian-German chemist Richard Kuhn (1900–1967) independentlydetermined the chemical structure of riboflavin and first

N N O

HO

HO

HO

OH

N C

O

HC C C N

C C

CH

HH

H

C

C H

H

H

H

H

C CH3C

H3C

CC

C

C


synthesized the compound. The name riboflavin is derivedfrom the fact that the vitamin was first found in associationwith the sugar ribose.

HOW IT IS MADE

Plants and microorganisms synthesize riboflavin natu-rally. Some foods rich in riboflavin are brewer’s yeast, darkgreen vegetables, mushrooms, legumes, nuts, milk and otherdairy products, sweet potatoes, and pumpkins. Bacteria thatlive in the human digestive tract are also able to synthesizesome riboflavin, but not enough to meet the body’s require-ment for the vitamin.

Riboflavin. Red atoms areoxygen; white atoms


are nitrogen. Gray sticksindicate double bonds. Striped

sticks show a benzene ring,P U B L I S H E R S R E S O U R C E G R O U P


RIBOFLAVIN

Riboflavin is produced synthetically using either thegenetically-modified bacterium Bacillus subtilis or a funguscalled Ashbya gossifyii. The bacteria or fungus are culturedin a large vat that has been seeded with small amounts ofriboflavin. Over time, the organisms generate large quanti-ties of riboflavin until some desired amount of the com-pound has been produced. The vat is then heated to atemperature sufficient to kill the bacteria or fungi, leavingcrystalline riboflavin behind. The riboflavin is then sepa-rated and purified.


The human body needs riboflavin to use oxygen effi-ciently in the metabolism of amino acids, fatty acids, andcarbohydrates. The vitamin is involved in the synthesis ofniacin (another B vitamin), it activates vitamin B6, and ithelps the adrenal gland to produce hormones. It helps thebody make antibodies to fight disease and infection, regulatesthe thyroid gland, and is important in maintaining healthyhair, nails, and skin. Riboflavin is especially important duringperiods of rapid growth because it is involved in the formationand growth of cells, especially red blood cells.

Interesting Facts

• The human body cannotstore riboflavin, so it isexcreted in the urine. Forthis reason, it is not dan-gerous to consume largedoses of riboflavin,although the consumptionof large amounts of thevitamin serves no biologi-cal purpose.

• Since riboflavin doesnot dissolve in water, itmust be converted to awater soluble form,

such as riboflavin-5-phosphate, for useas a food additive.

• The recommended dailydose of riboflavin foradults is 1.6 milligrams formen, 1.2 milligrams forwomen, 0.6 milligrams forchildren age four to eight,0.9 milligrams for childrenage nine to thirteen, and1.3 milligrams for teen-agers.


RIBOFLAVIN

In combination with vitamin A, riboflavin helps main-tain the mucous membranes that line the digestive tract.Pregnant women need riboflavin to help the fetus grow anddevelop. The vitamin is also essential for eye health. Somemedical professionals recommend riboflavin for the treat-ment of eye disorders, such as cataracts, sensitivity to brightlight, and bloodshot, burning, or itching eyes. Doctors havebegun experimenting with the use of riboflavin to treatmigraine headaches.

In spite of its many important functions in the body,riboflavin deficiencies do not lead to serious medical pro-blems or death. They may result in a delayed healing ofwounds or relatively minor medical conditions such as chei-losis (a reddening and soreness in the corners of the lips),angular stomatitis (cracking of the skin at the corner of thelips), dermatitis (an oily skin disorder), glossitis (a swollen,reddened tongue), and cracking around the nose. In all suchcases, however, a riboflavin deficiency by itself is almostnever the cause of the problem; instead, deficiencies of othervitamins in the B group are also involved.

Riboflavin deficiencies are very rarely seen in the UnitedStates because the vast majority of people consume a dietthat contains adequate amounts of the vitamin. Individuals

Words to Know

CARBOHYDRATE A group of sugars andstarches produced by plants and used asfood.

JAUNDICE A disease caused by malfunctionof the liver in which the skin and eyesbecome yellow.

LEGUME A member of the pea family ofplants, which includes peas and beans.

METABOLISM The process that includes allof the chemical reactions that occur incells by which fats, carbohydrates, andother compounds are broken down to

produce energy and the compoundsneeded to build new cells and tissues.





RIBOFLAVIN

most likely to suffer from riboflavin deficiency problems arethose with anorexia (a condition in which people refuse toeat adequate amounts of food), older people with poor diets,alcoholics (because alcohol impairs a person’s ability toabsorb and use the vitamin), and newborn babies being trea-ted for jaundice by exposure to ultraviolet light (becauselight destroys riboflavin).


‘‘Food Safety: From the Farm to the Fork.’’ European CommissionWeb Site.http://europa.eu.int/comm/food/fs/sc/scf/out18_en.html(accessed on November 3, 2005).

‘‘Riboflavin.’’ Linus Pauling Institute, Micronutrient Information.http://lpi.oregonstate.edu/infocenter/vitamins/riboflavin/(accessed on November 3, 2005).

‘‘Riboflavin.’’ MedlinePlus.http://www.nlm.nih.gov/medlineplus/ency/article/002411.htm (accessed on November 3, 2005).

‘‘Vitamin B2 (Riboflavin).’’ Herb & Supplement Encyclopedia.http://www.florahealth.com/flora/home/canada/healthinformation/encyclopedias/VitaminB2.asp (accessed onNovember 3, 2005).


RIBOFLAVIN

OTHER NAMES:Benzoylsulfonic

imide; benzoic sulfi-mide

FORMULA:C7H5NO3S


nitrogen, oxygen, sul-fur


STATE:Solid




decomposes


water; soluble inacetone and ethyl

alcohol

Saccharin

KE

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OVERVIEW

Saccharin (SAK-uh-rin) is a synthetic compound whosewater solutions are at least 500 times as sweet as table sugar.It passes through the human digestive system without beingabsorbed, so it has an effective caloric value of zero. It isused as a sugar substitute by diabetics or by anyone wishingto reduce their caloric intake.

Saccharin was the first artificial sweetener discovered. Itwas synthesized accidentally in 1879 when Johns Hopkinsresearchers Constantine Fahlberg (1850–1910) and Ira Remsen(1846–1927) were working on the development of new foodpreservatives. The story is told that Fahlberg accidentallyspilled one of the substances being studied on his hand. Sometime later, he noticed the sweet taste of the substance andbegan to consider marketing the product as an artificial sweet-ener. Fahlberg and Remsen jointly published a paper describ-ing their work, but Fahlberg, without Remsen’s knowledge,went on to request a patent for the discovery. He eventuallybecame very wealthy from proceeds of the discovery, none of

C C

C C

O

C C

C

S

O

N

H

O

HH

H

H


which he shared with Remsen. Remsen was later quoted assaying that ‘‘Fahlberg is a scoundrel. It nauseates me to hearmy name mentioned in the same breath with him.’’

In spite of its sweet taste, saccharin was used at first asan antiseptic, a substance that stops the growth of or killsbacteria. Before long, however, its primary use became that

Benzoic sulfinide. Red atoms areoxygen; white atoms are hydrogen;

black atoms are carbon; blue atom isnitrogen; and yellow atom is sulfur.Gray sticks indicate double bonds.

Striped sticks show a benzene ring.P U B L I S H E R S R E S O U R C E G R O U P


of an artificial sweetener. By 1902, it had become so popularin Germany that the German sugar industry lobbied for lawslimiting production of saccharin. Similar actions occurred inthe United States in 1907 and, by 1911, the federal govern-ment restricted use of the compound to overweight invalids.

A shortage of sugar during World War I (1914–1918) ledto the reintroduction of saccharin as a sweetening agent infoods. Another sugar shortage during World War II (1939–1945) saw a new boom in saccharin production. This time, thecompound’s popularity continued after the war ended.

Questions about saccharin’s safety have been raised anumber of times in the past. In 1969, for example, the sweet-ener cyclamate was found to be carcinogenic, and its use wasbanned in the United States. Doubts over saccharin’s safetyresurfaced, partly since it was often mixed with cyclamate inartificial sweeteners. In 1972, studies with rats suggestedthat saccharin too might be carcinogenic, and the U.S. Foodand Drug Administration imposed restrictions on the sweet-ener’s use. Later studies attempting to reproduce the 1972research were largely unsuccessful, and the status of sac-charin as a carcinogen remain unsettled.

In 1977, the Canadian government decided that sufficientevidence existed to ban the use of saccharin except for usewith diabetics and others with special medical problems. TheU.S. government considered taking similar action, but, aftermore than a decade of reviewing the evidence, decided toallow the use of saccharin among the general public. None-theless, the status of saccharin as a potential health hazardremains the subject of an active debate in the United Statesand other parts of the world.

HOW IT IS MADE

A number of methods are available for the synthesis ofsaccharin. For many years, the most popular process was onedeveloped by the Maumee Chemical Company of Toledo,Ohio, in 1950. This method begins with anthranilic acid(o-aminobenzoic acid; C6H4(NH2)COOH), which is treated suc-cessively with nitrous acid (HNO2), sulfur dioxide (SO2),chlorine (Cl2), and ammonia (NH3) to obtain saccharin.Another process discovered in 1968 starts with o-toluene,which is then treated with sulfur dioxide and ammonia toobtain saccharin.


SACCHARIN

Saccharin is not very soluble, so it is commonly madeinto its sodium or calcium salt (sodium saccharin or calciumsaccharin), both of which readily dissolve in water, for use indrinks and cooking. Saccharin is often blended with othersweeteners to reduce its metallic aftertaste.


Saccharin is used almost exclusively as an artificialsweetener in food and drinks to replace sugar. Its lack ofcalories makes it suitable for diet products and for medicalpreparations designed for people who must reduce their calo-ric intake. It also finds some small application as a foodpreservative, as an antiseptic agent, and as a brighteningagent in electroplating procedures.

Raw saccharin can be an irritant to the skin, eyes, andrespiratory system. If ignited, it burns with the release ofirritating fumes. Only individuals who come into contact

Interesting Facts

• The chemical companyMonsanto was founded in1901 for the sole purposeof making saccharin. Thecompany sold all of its

product to a single com-pany, the Coca-Cola com-pany, founded in the late1880s.

Words to Know

CARCINOGEN A substance that causes can-cer in humans or other animals.

ELECTROPLATING A process by which a thinlayer of one metal is deposited on top of asecond metal by passing an electric cur-rent through a solution of the first metal.

SALT A compound in which all of the hydro-gen ions are replaced by metal ions.



SACCHARIN

with large quantities of saccharin are likely to be concernedabout such safety problems, however.


Henkel, John. ‘‘Sugar Substitutes: Americans Opt for Sweetnessand Lite.’’ FDA Consumer. December 1999. Available online athttp://www.fda.gov/fdac/features/1999/699_sugar.html(accessed on November 3, 2005).

Nabors, Lyn O’Brien, ed. Alternative Sweeteners (Food Science and

Technology). Third revision. London: Marcel Dekker, 2001.

Ruprecht, Wilhelm. ‘‘Consumption of Sweeteners: An EvolutionaryAnalysis of Historical Development.’’http://www.druid.dk/conferences/nw/paper1/ruprecht.pdf(accessed on November 3, 2005).

‘‘Saccharin Sodium.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/s0073.htm(accessed on November 3, 2005).


SACCHARIN

OTHER NAMES:Silica, quartz, sand,

amorphous silica,silica gel, and others

FORMULA:SiO2

ELEMENTS:Silicon, oxygen


(inorganic)

STATE:Solid


MELTING POINT:Varies depending on

crystalline state;typically above

1700�C (3100�F)


SOLUBILITY:Solubility depends oncrystalline state; gen-

erally insoluble inwater; soluble inmany acids and

alkalis

Silicon Dioxide

KE

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OVERVIEW

Silicon dioxide (SILL-uh-kon dye-OK-side) is one of themost abundant chemical compounds on Earth. It makes upabout 60 percent of the weight of the Earth’s crust either asan independent compound (SiO2) or in combination withmetallic oxides that form silicates. Silicates are inorganiccompounds whose negative part is the SiO3 ion (groupingof atoms). An example is magnesium silicate, MgSiO3.

Silicon dioxide occurs as colorless, odorless, tasteless white orcolorless crystals or powder. Its many different forms can beclassified as crystalline, amorphous, or vitreous. In crystallineforms of silicon dioxide, all of the atoms that make up the sub-stances are arranged in orderly patterns that have the shape ofcubes, rhombohedrons, or other geometric figures. In amorphoussilicon dioxide, silicon and oxygen atoms are arranged randomly,without any clear-cut pattern. Vitreous silicon dioxide is a glassyform of the compound that may be transparent, translucent, oropaque. The various forms of silicon dioxide can be convertedfrom one form to another by heating and changes in pressure.

Si

O

O


An especially interesting form of silicon dioxide is silicagel, a powdery form of amorphous silicon dioxide that ishighly adsorbent. An adsorbent material (in contrast to anabsorbent material) is one that is capable of removing amaterial, such as water, ammonia, alcohol, or other gases,out of the air. The second material bonds weakly to the outersurface of silica gel particles. Silica gel is able to adsorbanywhere from 30 to 50 percent of its own weight in water

Silicon dioxide. Red atoms areoxygen and yellow atoms are

silicon. P U B L I S H E R S R E S O U R C E

G R O U P


SILICON DIOXIDE

from the surrounding atmosphere before it becomes satu-rated. The silica gel is not chemically altered by the processof adsorption and still feels dry even when saturated. Theadsorbed water can be driven off simply by heating the silicagel, allowing the material to regain its adsorbent properties.

HOW IT IS MADE

Although methods are available for synthesizing sili-con dioxide, there is no practical reason for doing so. Theabundant quantities of silicon dioxide found in theearth’s crust are sufficient to satisfy all industrial needs.Among the minerals and earths that contain silicon diox-ide in an uncombined form are quartz, flint, diatomite,stishovite, agate, amethyst, chalcedony, cristobalite, andtridymite.

Naturally occurring silicon dioxide can be treated by avariety of physical processes to change its form. For exam-ple, heating crystalline silicon dioxide above its meltingpoint and then cooling it again converts the compound intoits vitreous form, sometimes called natural glass. Silica gel ismade by treating sodium silicate (Na2SiO3) with sulfuric acid(H2SO4): Na2SiO3 + H2SO4 ! SiO2 + H2O + Na2SO4.

Interesting Facts

• Stardust, a U.S. NationalAeronautics and SpaceAdministration (NASA)spacecraft, used silica gelto collect particles of deb-ris from the tail of cometWild-2.

• Although silica gel hasbeen known since the mid-seventeenth century, prac-tical applications for thematerial were not discov-

ered until 1919 when Amer-ican Walter A. Patrick(1888–1969) patented anumber of processes forthe manufacture of thecompound. It still did notbecome widely popularuntil World War II (1939–1945), when the Americanmilitary found a number ofimportant uses for thecompound.


SILICON DIOXIDE


The primary use of silicon dioxide is in the buildingindustry. It is used to make ceramics, enamels, concrete,and specialized silica bricks used as refractory materials. Itis also one of the raw materials from which all kinds of glassare made. Vitreous silicon dioxide is an important constitu-ent of specialized types of glass, such as that used in makinglaboratory equipment, mirrors, windows, prisms, cells, andother kinds of optical devices. Silicon dioxide is also used asan anti-caking or thickening agent in a variety of foods andpharmaceutical products. Some other applications of silicondioxide include:

• In the manufacture of polishing and grinding materials;

• As molds for casting;

• In the production of elemental silicon;

• As a filler in many different kinds of products, includ-ing paper, insecticides, rubber products, pharmaceuti-cals, and cosmetics;

• As an additive in paints to produce a low-gloss finish;

• In the reinforcement of certain types of plastics.

The primary application of silica gel is as a drying agent.Packets of silica gel are found in many consumer products,such as electronic equipment, hardware tools, clothing, CDand DVD discs, and foodstuffs. Because of its ability toadsorb moisture from the surrounding air, silica gel preventsrust and other forms of oxidation. Silica gel also has similarapplications in industry. For example, it is used to dry com-pressed air, air conditioning systems, and natural gas. Thecompound is also used to bleach petroleum oils and as ananti-caking agent for cosmetics and pharmaceuticals.

Normal exposure to silicon dioxide is not consideredhazardous to the health of humans or other animals. Inhalingsilicon dioxide dust or fumes, however, may create problemsin the respiratory system. In low doses, inhaled silica cancause coughing, wheezing, and difficulty breathing. Inhigher doses, particles of silicon dioxide may lodge in thelungs and block the openings through which oxygen isabsorbed. Over long periods of exposure, a condition knownas silicosis may develop. Silicosis is a condition similar totuberculosis, lung cancer, or emphysema in which a person’sability to breathe normally is reduced, causing severe and


SILICON DIOXIDE

life-threatening long-term health problems. Individuals atgreatest risk for silicosis and other silicon dioxide-relatedproblems are those who cut, chip, drill, or grind objects thatcontain silica. During these processes, silica is reduced to afine powder that is easily inhaled. Wearing a mask duringthese operations is generally sufficient to protect a workerfrom inhaling these fumes and particles.


Brown, David. ‘Walter Patrick: Preservationist of the First Order.’’Mount Washington Newsletter. Spring 2003. Also availableonline athttp://www.mwia.org/Newsletters/MWIANewsletter_Spring%202003.pdf (accessed on December 10, 2005).

Brownlee, Don. ‘‘An Exciting Encounter with a Cold Dark Mysterious Body from the Edge of the Solar System.’’ Jet PropulsionLaboratory. California Institute of Technology.http://stardust.jpl.nasa.gov/news/news101.html (accessed onDecember 10, 2005).

‘‘Crystalline Silica Exposure.’’ U.S. Occupational Safety and HealthAdministration.http://www.osha.gov/Publications/osha3177.pdf (accessed onDecember 10, 2005).

Scheer, James F. ‘‘Silica: Health and Beauty from Nature.’’ Better

Nutrition (December 1997): 38 43. Also available online athttp://www.findarticles.com/p/articles/mi_m0FKA/is_n12_v59/ai_20086185 (accessed on December 10, 2005).

‘‘Silica Gel.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/s1610.htm(accessed on December 10, 2005).

‘‘Silica Silicon Dioxide.’’ Azom.com.http://www.azom.com/details.asp?ArticleID=1114 (accessed onDecember 10, 2005).

Words to Know


REFRACTORY A material with a highmelting point, resistant to melting,

often used to line the interior ofindustrial furnaces.


SILICON DIOXIDE

‘‘What Is Silica Gel and Why Do I Find Packets of It in EverythingI Buy?’’ How Stuff Works.http://science.howstuffworks.com/question206.htm (accessedon December 10, 2005).

See Also Calcium Silicate; Sodium Silicate


SILICON DIOXIDE

OTHER NAMES:Silver(I) iodide

FORMULA:AgI

ELEMENTS:Silver, iodine


ganic)

STATE:Solid





organic solvents;soluble in solutionsof sodium chloride,potassium chloride,

and ammoniumhydroxide

Silver Iodide

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OVERVIEW

Silver iodide (SILL-ver EYE-oh-dide) is a light yellowcrystalline or powdery material that darkens on exposure tolight. The darkening occurs because silver ions (Ag+; silveratoms with a positive charge) are converted to neutral silveratoms (AgO) that are dark gray in color. Silver iodide is usedprimarily in photography and in cloud-seeding experiments.

HOW IT IS MADE

Silver iodide occurs naturally in the mineral odargyrite(also known as iodyrite), from which it can be extracted. Thecompound is extracted by adding concentrated hydriodic acid(HI) to the mineral, which dissolves out the silver iodide. Thesilver iodide can then be recovered by evaporating the solu-tion and purifying the product. The compound can also bemade more easily by reacting silver nitrate (AgNO3) withsodium or potassium iodide (NaI or KI) under a ruby redlight. The colored light is used to prevent oxidation of the

Ag I


silver ion to silver metal during the preparation: AgNO3 +NaI ! AgI + NaNO3.


The primary use of silver iodide is in photography. Thecompound was first used for this purpose in the early nine-teenth century by the French experimenter Louis JacquesMande Daguerre (1787–1851). Daguerre first covered a sheetof copper metal with a thin layer of silver. He then exposedthe plate to iodine vapors, converting the silver metal tosilver iodide. The photograph was taken by exposing theplate to light, which converted colorless silver ions in silveriodide back to grayish silver atoms. After exposure, the platewas treated with magnesium vapor, which adhered to theparts of the plate that had been exposed to light. Theunreacted silver iodide was then washed off the plate, reveal-ing an image on the plate. The fundamental principleinvented by Daguerre is still used today in taking photo-graphs with photograph film containing silver iodide.

The other major use for silver iodide is in cloud seeding.Cloud seeding is the process by which some foreign mate-rial—usually silver iodide or dry ice (solid carbon dioxide)—isdropped into a rain cloud. The crystals of silver iodide orcarbon dioxide provide nuclei—tiny cores—on which watercan condense to form water droplets. The process of cloudseeding was first developed in the 1940s by American che-mist Vincent Schaefer (1927–1993). Schaefer used crushed

Silver iodide. Turqouise atomis sliver and yellow atom is

iodine. P U B L I S H E R S R E S O U R C E

G R O U P


SILVER IODIDE

dry ice dropped from an airplane into a cloud in his firstexperiments. His initial experiments proved to be successful,with rain or snowstorms resulting from this seeding.

For three decades, researchers attempted to modify andimprove Schaefer’s techniques so as to be able to use cloudseeding to produce rain on demand. One step in that direc-tion was the effort by General Electric scientist BernardVonnegut (1914–1997) to use silver iodide crystals ratherthan dry ice for seeding. Although these experiments pro-duced moderately successful results, many scientists even-tually lost confidence in the process of cloud seeding as areliable method for producing rain. By the early twenty-firstcentury, the process was being used on only a small scale inisolated areas in efforts to produce rain. The problem is thatassessing the success of cloud seeding is very difficult.Because the process requires that clouds are already in anarea, it is difficult to determine whether rain or snow falls asa result of cloud seeding or as a result of natural processes. In2003, the National Academy of Sciences reached the conclu-sion that no reliable scientific evidence exists to suggestthat cloud seeding produces more rain or snow than wouldoccur naturally. The American Meteorological Society hastaken a somewhat more optimistic view, suggesting thatcloud seeding may increase precipitation by up to 10 percent.

Some concerns have been expressed about the environ-mental and health effects of using silver iodide for cloudseeding. However, only small amounts of silver iodide arereleased into the atmosphere. That which does fall to earthdoes not dissolve in water and so is unlikely to enter acommunity water supply. Tests have shown that the concen-

Interesting Facts

• The United States govern-ment spent about $19 mil-lion per year in the 1970sfor cloud seeding experi-ments. By the late 1990s,that amount had been

reduced to about $500,000as doubts were raisedabout the effectiveness ofthe procedure.


SILVER IODIDE

tration of silver iodide in rainwater is far below the 50micrograms per liter that has been deemed safe by the U.S.Public Health Service. The primary health concern for work-ers who handle silver iodide is a condition known as argyreia,in which the skin is stained a bluish black color by thecompound.


‘‘Chemistry of Photography.’’ Cheresources.http://www.cheresources.com/photochem.shtml (accessed onNovember 3, 2005).

Fukuta, Norihiko. ‘‘Cloud Seeding Clears the Air.’’ Physics in

Action (May 1998). Also available online athttp://physicsweb.org/articles/world/11/5/3/1 (accessed onNovember 3, 2005).

‘‘Silver Iodide.’’ ESPI Metals.http://www.espimetals.com/msds’s/silveriodide.pdf (accessedon November 3, 2005).

‘‘Silver Iodide.’’ H&S Chemical.http://www.hschem.com/msds/silverIodide.htm (accessed onNovember 3, 2005).

Zertuche, Casey. ‘‘Every Cloud Has a Silver Lining.’’ The DailyTexan (April 12, 2004). Also available online athttp://www.dailytexanonline.com/media/paper410/news/2004/04/12/Focus/Every.Cloud.Has.A.Silver.Lining 657354.shtml?norewrite&sourcedomain=www.dailytexanonline.com(accessed on November 3, 2005).


SILVER IODIDE

OTHER NAMES:Silver(I) nitrate; lunar

caustic

FORMULA:AgNO3

ELEMENTS:Silver, nitrogen,

oxygen


STATE:Solid



BOILING POINT:440�C (824�F);

decomposes

SOLUBILITY:Soluble in water, gly-

cerol, and hot ethylalcohol; moderately

soluble in acetone

Silver Nitrate

KE

YF

AC

TS

OVERVIEW

Silver nitrate (SILL-ver NYE-trate) is a colorless to trans-parent to white crystalline solid with no odor and a bittermetallic taste. In pure form, the compound is not affected bylight, but trace amounts of organic impurities may catalyzethe conversion of silver ions (Ag+; silver atoms with a posi-tive charge) to grayish neutral silver atoms (AgO) that givethe salt a grayish tint. Silver nitrate is the most widely usedof all silver compounds, finding application in the synthesisof other silver compounds, as a catalyst in certain industrialchemical reactions, as an antiseptic and germicide, and inphotographic processes.

The therapeutic effects of silver compounds, includingsilver nitrate, have been known for many centuries. Boththe Greeks and Romans, for example, used aqueous solu-tions of silver nitrate to treat wounds and cuts. In 1881,the German physician Carl Crede (1819–1892) developedthe practice of applying a 2 percent solution of silvernitrate to the eyes of newborn babies to prevent gonorrheal

O

O- O-

N+Ag+


ophthalmia, a bacterial infection of the eyes that mayresult in blindness in a child.

The use of silver nitrate in printing and photographydates to discoveries made in the 1720s by the German che-mist Johann Schulze (1687–1744). Schulze found that a mix-ture of silver, nitric acid, and chalk turns purple or blackwhen exposed to light. That simple discovery formed thebasis of the modern science of photography. In 1802, ThomasWedgwood (1771–1805), son of the founder of the famousWedgwood pottery company, used silver nitrate to maketemporary negative prints on paper, producing shades ofgray as well as pure black and white. In 1835, the Britishmathematician William Henry Fox Talbot (1800–1877) madethe first permanent paper negative from paper coated withsilver nitrate and common table salt (sodium chloride).

Two years later, the French inventor Louis JacquesMande Daguerre (1787–1851) coated a copper plate with silverand washed it with nitric acid to create a plate on which hemade the first Daguerreotype, an early form of photography.By the 1850s, Daguerre’s technique was in wide use, with thesubstitution of glass plates coated with silver nitrate toobtain images produced by exposing the plates to light. Bythe end of the nineteenth century, emulsions of silver nitratein celluloid were being used for making photographs, a pro-cess that was modified in the 1930s by the substitution of

Silver nitrate. Red atoms areoxygen; blue atom is nitrogen;and turquoise atom is silver.Gray sticks indicate double

bonds. P U B L I S H E R S R E S O U R C E

G R O U P


SILVER NITRATE

cellulose acetate for celluloid. Silver nitrate remains animportant component of the photographic process today.

HOW IT IS MADE

Silver nitrate is made by dissolving metallic silver inweak nitric acid.

2Ag + 2HNO3 ! 2AgNO3 + H2

The solution is then evaporated to recover the crystallinesilver nitrate, which is heated to remove impurities, dis-solved in water, and re-purified.


The primary use of silver nitrate is in the production ofother silvers salts used in the production of photographic film.Compounds such as silver bromide (AgBr) and silver iodide(AgI) decompose when exposed to light, forming free silver:

AgBr ! AgO + Br– and AgI ! AgO + I–

While silver bromide and silver iodide are nearly color-less, the free silver atoms formed in this reaction are black.Thus, portions of a photographic film that have been exposedto light turn black where free silver has formed.

In addition to its use in treating the eyes of newbornbabies, silver nitrate has a number of other medical applica-tions. It is used as a germicidal wall spray in medical facil-ities, as a topical (on the skin) anti-infective agent, for thecauterization of wounds, and as a general antiseptic. Cauter-ization is the process by which the skin surrounding a wound

Interesting Facts

• Film speed numbers, suchas ISO 100 or ISO 4000,correspond to the size ofsilver nitrate particles onthe film. The finer thegrain, the more detailedthe image quality.

• Silver nitrate is not toxicto humans or othermammals. But it is toxicto fish and other aquaticorganisms. For this reason,it should not be discardedin lakes and rivers.


SILVER NITRATE

is burned in order to seal the wound. Other uses of silvernitrate include:

• The silvering of mirrors, a process by which a thincoating of silver metal is attached to the back of a pieceof glass to form a mirror;

• As a catalyst in the manufacture of ethylene oxide, animportant raw material in the production of plastics;

• In the silver plating of metals and plastics;

• In the manufacture of indelible printing inks;

• For hair dye; and

• As a flower preservative, a process that involves addinga small amount of silver nitrate solution to the water inwhich flowers are stored.

Silver nitrate is an irritant that can cause inflammationand burning of the skin, eyes, and respiratory system. It isalso toxic by ingestion. In sufficient amounts, silver nitratecan cause severe damage to the respiratory tract and lungs,blindness, and even death. Solutions of silver nitrate canstain the skin dark purple or black, although such stains donot necessarily indicate that serious damage has occurred.


Dunn, Peter M. ‘‘Dr Carl Crede (1819 1892) and the Prevention ofOphthalmia Neonatorum.’’ Archives of Diseases in Childhood

(September 2000): F158 F159. Also available online athttp://fn.bmjjournals.com/cgi/content/full/83/2/F158(accessed on November 5, 2005).

Words to Know

ANTISEPTIC A chemical that prevents thegrowth of bacteria and viruses that causedisease.

AQUEOUS Referring to solution that con-sists of some material dissolved in water.

CATALYST A material that increases therate of a chemical reaction without

undergoing any change in its ownchemical structure.

EMULSION A temporary mixture of twoliquids that normally do not dissolvein each other.

THERAPEUTIC DRUG A compound thathas healing properties.


SILVER NITRATE

Grimm, Tom, and Michele Grimm. The Basic Book of Photography.

New York: Plume Books, 2003.

Patnaik, Pradyot. ‘‘Silver Nitrate.’’ Handbook of Inorganic Chemi

cals. New York: McGraw Hill, 2003, 841 842.

‘‘Silver Nitrate.’’ New Jersey Department of Health and SeniorServices.http://nj.gov/health/eoh/rtkweb/1672.pdf (accessedon November 5, 2005).

See Also Cellulose Nitrate; Silver Iodide


SILVER NITRATE

OTHER NAMES:Silver oxide; argen-

tous oxide

FORMULA:Ag2O

ELEMENTS:Silver, oxygen

COMPOUND TYPE:Metallic oxide (inor-

ganic)

STATE:Solid


MELTING POINT:Decomposes at about

200�C (400�F)


SOLUBILITY:Slightly soluble inwater; insoluble in

ethyl alcohol

Silver(I) Oxide

KE

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AC

TS

OVERVIEW

Silver(I) oxide (SILL-ver one OK-side) is an odorless darkbrown or black powder with a metallic taste. It is used pri-marily for polishing glass, the purification of water, andcoloring glass.

HOW IT IS MADE

Silver(I) oxide is made by reacting silver nitrate (AgNO3)with sodium or potassium hydroxide (NaOH or KOH). Forexample:

2AgNO3 + 2NaOH ! Ag2O + 2NaNO3 + H2O

The silver(I) oxide settles out as a precipitate that canthen be washed and purified.


Silver(I) oxide finds limited commercial and industrialapplication. It is used as an ingredient in the manufacture of

Ag+ Ag+

O2–


glass to give a yellowish caste to the glass. It is also acomponent of mixtures used to polish glass, including theglass used in optical lenses. Silver(I) oxide is also used as acatalyst in certain industrial operations and in some waterpurification systems.

Silver(I) oxide is a skin, eye, and respiratory irritantthat may cause coughing, wheezing, shortness of breath,and pulmonary edema (accumulation of fluid in the lungs).It can also cause burning of the eyes and skin. Ingestion canproduce burning of the gastrointestinal tract accompaniedby nausea, vomiting, and abdominal pain. Long-term expo-sure to silver(I) oxide can cause argyreia, a bluish-graydiscoloration of the skin, eyes, and mucous membranes(the soft tissues lining the breathing and digestivepassages).

Silver oxide. Red atom isoxygen and silver atoms are

silver. P U B L I S H E R S R E S O U R C E

G R O U P

Words to Know

AQUEOUS Referring to a solution thatconsists of some material dissolvedin water.

PRECIPITATE A solid material that settlesout of a solution, often as the resultof a chemical reaction.


SILVER(I) OXIDE


‘‘Material Safety Data Sheet.’’ IC Controls.http://www.iccontrols.com/files/a1100122.pdf (accessed onNovember 5, 2005).

‘‘Silver(I) Oxide.’’ Patnaik, Pradyot. Handbook of Inorganic Chemi

cals. New York: McGraw Hill, 2003, 842 843.

‘‘Silver Oxide.’’ Chem007.http://www.chem007.com/specification_d/chemicals/supplier/cas/Silver%20oxide.asp (accessed on November 5, 2005).


SILVER(I) OXIDE

OTHER NAMES:Argentous sulfide

FORMULA:Ag2S

ELEMENTS:Silver, sulfur

COMPOUND TYPE:Binary salt(inorganic)

STATE:Solid




decomposes


soluble in nitric acid,sodium cyanide

(NaCN), and potassiumcyanide (KCN)

Silver(I) Sulfide

KE

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AC

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OVERVIEW

Silver(I) sulfide (SILL-ver one SUL-fide) is a grayish-blackheavy powder. Most people are familiar with the compound

as tarnish, the black coating that covers silver tableware andjewelry when they are exposed to the air.

HOW IT IS MADE

Silver(I) sulfide occurs naturally as the mineralsacanthite and argentitde, from which they can be extracted

by grinding, crushing, and washing the mineral ore. Thecompound can also be prepared synthetically by passing

hydrogen sulfide (H2S) gas through an aqueous solution ofsilver nitrate.

H2S + 2AgNO3 ! Ag2S + 2HNO3

The silver(I) sulfide precipitates out of solution and can befiltered and purified by washing with hot water.

Ag+

Ag+ S2–



Naturally occurring silver(I) sulfide can be used as asource of silver metal. The sulfide is roasted in air, convert-ing silver(I) sulfide to silver(I) sulfate. The sulfate can thenbe treated chemically to obtain silver metal. The processfinds little commercial application since other, more econom-ically efficient, sources of silver are available.

The primary use of silver(I) sulfide is in the productionof glazes for ceramics. The compound gives a glassy ormetallic sheen to the glaze. It is also used in the processknown as niello, first used by the early Greeks and Romansto produce a black, metallic inlay on the surface of pottery.

Silver(I) sulfide is an irritant to the skin, eyes, andrespiratory system. No long-term effects of exposure to thecompound have been reported. When absorbed through cutsin the skin or ingested it may produce a condition known asargyreia, which causes skin and mucous membranes todevelop a bluish-black color.


Krampf, Robert. ‘‘Cleaning the Silver.’’ Edgerton Explorit Center.http://www.edgerton.org/kidscorner/silver.html (accessed onNovember 5, 2005).

‘‘Material Safety Data Sheet.’’ ESPI Metals.http://www.espimetals.com/msds’s/silversulfide.pdf (accessedon November 5, 2005).

Silver sulfide. Silver atoms aresilver and yellow atom is sulfur.P U B L I S H E R S R E S O U R C E G R O U P


SILVER(I) SULFIDE

‘‘Mineral Acanthite/Argentite, The.’’ Amethyst Galleries.http://mineral.galleries.com/minerals/sulfides/acanthit/acanthit.htm (accessed on November 5, 2005).

Patnaik, Pradyot. Handbook of Inorganic Chemicals. New York:McGraw Hill, 2003, 845.

Interesting Facts

• Tarnish is caused by achemical reaction betweensilver in tableware andsulfur compounds thatoccur in eggs. Tarnish canbe removed by soakingtableware in a solution ofwarm baking soda in waterin a pan lined withaluminum foil. A chemicalreaction occurs in whichaluminum replaces silver,forming aluminum sulfide(Al2S3) and free silver:2Al + 3Ag2S! 6Ag + Al2S3.The reaction occurs only ifthe silver tableware is in

physical contact with thealuminum foil because anelectric current must flowbetween the two metals.

• The silver present in elec-tric contacts exposed tohydrogen sulfide gas maybegin to grow long fila-ments known as silver

whiskers. These whiskershave been known to growas long as 8 centimeters(3 inches) in length and cancause catastrophic failuresin the electrical contacts.

Words to Know

AQUEOUS Referring to a solution that con-sists of some material dissolved in water.




SILVER(I) SULFIDE

FORMULA:NaC2H3O2

ELEMENTS:Sodium, carbon,

hydrogen, oxygen


STATE:Solid




decomposes


soluble in ether;slightly soluble in

ethyl alcohol

Sodium Acetate

KE

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AC

TS

OVERVIEW

Sodium acetate (SO-dee-um ASS-uh-tate) is a colorless,odorless crystalline solid that often occurs as the trihydrate:NaC2H3O2�3H2O. A hydrate is a chemical compound formedwhen one or more molecules of water is physically added tothe molecule of some other substance. Sodium acetate trihy-drate has three molecules of water of hydration for everyNaC2H3O2 unit. Anhydrous sodium acetate readily converts tothe trihydrate because it is very hygroscopic. A hygroscopiccompound is one that readily absorbs moisture from the air.

HOW IT IS MADE

Sodium acetate is prepared by reacting either sodium hydro-xide (NaOH) or sodium carbonate (Na2CO3) with acetic acid(HC2H3O2). With sodium hydroxide, for example, the reaction is:

NaOH + HC2H3O2 ! NaC2H3O2 + H2O

The sodium acetate forms as the trihydrate, which isthen recovered by evaporating the reacting solution. The

O

C Na+H3C O–


anhydrous salt can be prepared by heating the hydrate todrive off the water of hydration.


Sodium acetate is used in a number of industries. In thetextile industry, it is used as a mordant in the dyeing offabrics and to stabilize and improve the finish of fabrics. The

Sodium acetate trihydrate.

Red atoms are oxygen;hydrogen atoms are white;

black atoms are carbon;turquoise atom is sodium. Gray

stick indicates double bond.P U B L I S H E R S R E S O U R C E G R O U P


SODIUM ACETATE

cosmetics industry uses sodium acetate as a buffering agentin a variety of personal care products. A buffering agent is asubstance that maintains the acidity of a product within acertain desired range. Sodium acetate is also used by foodproducers for the same reason, assuring that a variety offoods have an acidity sufficient to protect the food fromdecaying, but not so acidic as to have an unpleasant taste.Some other applications of sodium acetate include:

• In heat packs to relieve stiffness and pain, to keephands and feet warm, and to warm baby bottles;

• In the production of soaps, where it reacts with strongbases to reduce the harshness of the final product;

• In dialysis machines, used for people whose kidneys arenot working properly, to provide the sodium ions (Na+)to maintain proper electrolyte balance in the body;

• As a diuretic, a drug used to promote urination;

• As an expectorant in drugs used to promote coughing tohelp bring up mucous;

Interesting Facts

• In 1995, officials in Michi-gan tested sodium acetatetrihydrate as a deicing saltfor airport runways.Experiments showed, how-ever, that the anhydroussalt worked better thanthe trihydrate for thispurpose.

• Sodium acetate has alsobeen used as a deicer inparking garages. The com-pound is preferred tosodium chloride, widelyused as a deicing com-pound, because sodium

chloride corrodes steelrods buried in concreteand sodium acetate doesnot.

• Heat packs sometimescontain a solution ofsodium acetate trihydratecooled below its freezingpoint. When the pack isactivated, the compoundfreezes very rapidly,releasing the heat that hadbeen stored in its super-cooled phase.


SODIUM ACETATE

• As a veterinary treatment for bovine ketosis, a condi-tion caused by low blood sugar in cows that results in awasting or weakening of the animal;

• As a buffer in the developing of photographs;

• In the tanning of hides to obtain a more even and morerapid absorption of the tanning material; and

• In the purification of glucose.

Sodium acetate is a mild irritant to the skin, eyes, andrespiratory system. If inhaled, it may cause inflammation ofthe throat and lungs. At the level it appears in most house-hold products, it presents a very low hazard to the averageperson.


‘‘How Do Sodium Acetate Heat Pads Work?’’ How Stuff Works.http://home.howstuffworks.com/question290.htm (accessedon November 5, 2005).

‘‘Material Safety Data Sheet: Sodium Acetate Trihydrate.’’ IowaState University, Department of Chemistry.http://avogadro.chem.iastate.edu/MSDS/NaOAc 3H2O.htm(accessed on November 5, 2005).

‘‘Sodium Acetate, Anhydrous.’’ Cornell Material Safety DataSheets.http://msds.ehs.cornell.edu/msds/msdsdod/a73/m36008.htm#Section3 (accessed on November 5, 2005).

‘‘Sodium Acetate Anhydrous Physical Properties.’’ Jarchem Industries.http://www.jarchem.com/sodium acetate anhydrous.htm(accessed on November 5, 2005).

Words to Know

ANHYDROUS Lacking water of hydration.

MORDANT A substance used in dyeing andprinting that reacts chemically with both a

dye and the material being dyed to helphold the dye permanently to the material.


SODIUM ACETATE

OTHER NAMES:Bicarbonate of soda;

baking soda

FORMULA:NaHCO3

ELEMENTS:Sodium, hydrogen,

carbon, oxygen


STATE:Solid


MELTING POINT:about 50�C (120�F);

decomposes


decomposes



Sodium Bicarbonate

KE

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AC

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OVERVIEW

Sodium bicarbonate (SO-dee-um bye-KAR-bun-ate) is awhite, odorless, crystalline solid or powder that is stable in

dry air, but that slowly decomposes in moist air to formsodium carbonate. The compound’s primary uses are as an

additive in human and animal food products.

Sodium bicarbonate has been used by humans forthousands of years. Ancient Egyptian documents mention

the use of a sodium bicarbonate and sodium chloride solu-tion in the mummification of the dead. For centuries,

people around the world have used sodium bicarbonate asa leavening agent for baking. A leavening agent is a

substance that causes dough or batter to rise. Sodiumbicarbonate produces this effect because, when heated ordissolved in water, it breaks down to produce carbon diox-

ide (CO2) gas:

2NaHCO3 ! Na2CO3 + CO2 + H2O

O

COH

Na+O-


Since all the compounds present in this reaction are safefor human consumption, sodium bicarbonate makes an idealleavening agent.

Commercial production of sodium bicarbonate as bakingsoda dates to the late 1700s. In 1846, Connecticut physician

Austin Church (1799–?) and John Dwight (1819–?) of Dedham,Massachusetts, founded a company to make and sell sodium

bicarbonate. They started their company in the kitchen ofDwight’s home, making the product by hand and packing itin paper bags for sale to neighbors. The Church-Dwight

operation grew over the years to become the largest producerof household baking soda, now sold under the name of Arm &

Hammer� baking soda. The company still produces 90 per-cent of all the baking soda used for household purposes in

the United States. Consumers use the product for cooking,cleaning, and deodorizing homes.

Sodium bicarbonate. Redatoms are oxygen; white atom

is hydrogen; black atom iscarbon; and turquoise atom issodium. Gray stick indicates

double bond. P U B L I S H E R S



SODIUM BICARBONATE

HOW IT IS MADE

Sodium bicarbonate is made commercially by one of twomethods. In the first method, carbon dioxide gas is passedthrough an aqueous solution of sodium carbonate (Na2CO3):

Na2CO3 + CO2 + H2O ! 2NaHCO3

Since the bicarbonate is less soluble than the carbonate,it precipitates out of solution and can be removed by filtra-tion.

Sodium bicarbonate is also obtained as a byproduct ofthe Solvay process. The Solvay process was invented in thelate 1850s by Belgian chemist Ernest Solvay (1838–1922)primarily as a way of making sodium carbonate. Sodiumcarbonate had long been a very important industrial chemi-cal for which no relatively inexpensive method of prepara-tion existed. Solvay developed a procedure by which sodiumchloride is treated with carbon dioxide and ammonia, result-ing in the formation of sodium bicarbonate and ammoniumbicarbonate. The sodium bicarbonate is then heated to obtainsodium carbonate. Although sodium carbonate is the desiredproduct in this reaction, sodium bicarbonate can also beobtained by deleting the final step by which it is convertedinto sodium carbonate.


An estimated 560,000 metric tons (615,000 short tons) ofsodium bicarbonate were consumed in the United States in2003. About one-third of that amount was used by the foodproducts industry, primarily in the manufacture of bakingsoda (pure sodium bicarbonate) and baking powder (a mix-ture of sodium bicarbonate and at least one other compound).

Interesting Facts

• Sodium bicarbonate is avery effective cleaningagent for certain materi-als. In the 1980s, restorers

used an aqueous solutionof the compound to cleanthe Statue of Liberty.


SODIUM BICARBONATE

Baking powder differs from baking soda in that it includesan acidic compound that reacts with sodium bicarbonate toproduce carbon dioxide. One of the most common compoundsmixed with sodium bicarbonate in baking powder is tartaricacid (HOOC(CHOH)2COOH), or its salt, potassium bitartrate(HOOC(CHOH)2COOK). Baking powder is a more efficient lea-vening agent in baking than is baking soda by itself. Bakingsoda is also used as an additive in foods and drinks to provideeffervescence (a bubbling, fizzing, or sparkling effect) or tomaintain an acidic environment in the food. The acidityprovides a sharp taste and helps to preserve a food.

The second largest use of sodium bicarbonate is as anadditive in animal feed. As with human foods, it maintainsthe proper acidity of an animal’s feed, improving its abilityto digest and absorb its food.

Sodium bicarbonate is also used in a number of pharma-ceutical applications. For example, it is a common ingredientin antacids, products designed to relieve heartburn, acidindigestion, sour stomach, and other discomforts caused byovereating or improper foods. Some pharmaceuticals, such asAlka-Seltzer�, contain a combination of citric acid andsodium bicarbonate. The citric acid helps the sodium bicar-bonate dissolve more quickly and produces more efferves-cence when the tablet is dissolved in water.

Sodium bicarbonate is also used in cleaning products onboth a household and industrial level. Many householders usecommercial baking soda, such as that sold by the Arm &

Hammer company, to clean kitchen and bathroom appliances,such as sinks, stoves, and toilet bowls. Industries also usesodium bicarbonate filters to remove sulfur dioxide and otherpollutants in flu gases released from factory smokestacks. Thecompound is also used in the treatment of wastewater to main-tain proper acidity, remove certain odors (such as those ofsulfur dioxide), and destroy bacteria. Some communities haveused aqueous solutions of sodium bicarbonate sprayed at highpressure to remove graffiti; paint; soot and smoke residues; andmold from buildings, walls, and other public structures.

Some other applications of sodium bicarbonate include:

• As a component of fire extinguishers; when it comesinto contact with an acid in the fire extinguisher, thesodium bicarbonate releases carbon dioxide and a flowof water under pressure to fight the fire;


SODIUM BICARBONATE

• As a blowing agent in the preparation of plastics; blow-ing agents are substances that produce large volumes ofgas that convert a molten product into a foamy product;

• In the manufacture of other sodium compounds;

• For gold and platinum plating; and

• To prevent the growth of mold on timber.

Sodium bicarbonate is considered safe when handled oringested in reasonable amounts. As with any chemical, how-ever, excessive amounts of the compound can have harmfuleffects. When ingested in large amounts, sodium bicarbonatecan cause stomach cramps, gas, upset stomach, vomiting,frequent urination, loss of appetite, and blood in the urineand stools.


‘‘Pure Baking Soda.’’ Arm & Hammer�.http://www.armhammer.com/ (accessed on November 8, 2005).

Snyder, C. H. The Extraordinary Chemistry of Ordinary Things,

4th ed. New York: John Wiley and Sons, 2002.

‘‘Sodium Bicarbonate.’’ Chemical Land 21.http://www.chemicalland21.com/arokorhi/industrialchem/inorganic/SODIUM%20BICARBONATE.htm (accessed on November 8, 2005).

‘‘Sodium Bicarbonate.’’ DC Chemical Co., Ltd.http://www.dcchem.co.kr/english/product/p_basic/p_basic02.htm (accessed on November 8, 2005).

See Also Carbon Dioxide; Citric Acid; Sodium Carbonate

Words to Know




SODIUM BICARBONATE

OTHER NAMES:Anhydrous salt: soda

ash; Solvay soda;decahydrate: sal

soda; washing soda(see Overview)

FORMULA:Na2CO3

ELEMENTS:Sodium, carbon, oxy-

gen


STATE:Solid




begins to decomposebelow melting point



Sodium Carbonate

KE

YF

AC

TS

OVERVIEW

Sodium carbonate (SO-dee-um KAR-bun-ate) is an odorlesswhite powder or crystalline solid with an alkaline taste.(Baking soda is another substance with an alkaline taste.) Itis hygroscopic, meaning that it has a tendency to absorbmoisture from the air. It also exists as the monohydrate(Na2CO3�H2O) and as the decahydrate (Na2CO3�10H2O), eachwith slightly different physical properties from those of theanhydrous salt. The anhydrous form of sodium carbonate iscommonly known as soda ash, while the decahydrate is oftencalled sal soda or washing soda. Sodium carbonate has longbeen one of the most important chemical compounds pro-duced in the United States. Its primary use is in the manu-facture of glass and other chemicals.

HOW IT IS MADE

Humans have known about and used sodium carbonatefor thousands of years. The ancient Egyptians extracted thecompound from a mineral known as natron found in dry lake

O

CNa+ Na+O- O-


bottoms. Natron is a combination of sodium carbonate andsodium bicarbonate. The Egyptians used sodium carbonate inthe mummification of dead bodies. The compound driedout the bodies of the dead and prevented them from decay-ing. The technique was so effective that some mummifiedbodies over 3,000 years old are in as good a condition todayas they were when the person died. Over the centuries,sodium carbonate was also produced by the combustion oforganic matter, especially seaweed. This method of produc-tion accounts for the compound’s common name of soda ash(ash containing sodium compounds).

The burning of dead plants does not produce very largequantities of sodium carbonate, so early chemists searchedfor synthetic methods of producing the increasingly impor-tant compound. The first breakthrough in that searchoccurred in 1791 when French chemist Nicolas Leblanc(1742–1806) invented a method for making sodium carbonatethat became the industry standard for nearly a century. Inthe Leblanc method, sodium chloride (NaCl) is treated withsulfuric acid (H2SO4) to make sodium sulfate (Na2SO4) andhydrochloric acid (HCl). The sodium sulfate is then heatedwith charcoal (nearly pure carbon) and limestone (CaCO3).

Sodium carbonate. Red atomsare oxygen; black atom is

carbon; and turquoise atomsare sodium. Gray stickindicates double bond.



SODIUM CARBONATE

The product of this reaction is a dark ashy material thatcontains sodium carbonate, calcium sulfide, carbon dioxide,and other byproducts:

Na2SO4 + 2C + CaCO3 ! Na2CO3 + CaS + 2CO2

The sodium carbonate is extracted from this mixture andpurified. The Leblanc invention was one of the great break-throughs in the early years of chemical science. It madepossible, among other things, the mass production of soapfor the first time in human history.

As important as Leblanc’s invention was, it suffered fromone serious drawback: It required large amounts of energy.For this reason, chemists were always on the lookout for analternative method for producing sodium carbonate that wasless energy-intensive. That breakthrough came in 1861 whenBelgian chemist Ernest Solvay (1838–1922) found a new wayto make the important compound. Solvay found that treatingsodium chloride with carbon dioxide and ammonia resultedin the formation of sodium bicarbonate and ammoniumbicarbonate. Simply heating the sodium bicarbonate con-verts the bicarbonate to the carbonate. Like Leblanc’s dis-covery, the Solvay process is regarded as one of the greataccomplishments in the first century of industrial chemistry.By 1900, almost all of the sodium carbonate produced in theworld was being made by the Solvay process.

That situation has changed. Today the most importantsource of sodium carbonate is natural minerals, such asthermonatrite (sodium carbonate monohydrate; Na2CO3�H2O)or natron (or natrite; sodium carbonate decahydrate;Na2CO3�10H2O). These minerals are obtained from rockydeposits or from brines that are rich in the compound. Brineis water that is saturated with salts, such as sodium chloride,potassium chloride, and sodium carbonate. It is similar to,but saltier than, seawater.


About half of all the sodium carbonate produced in theUnited States is used to make glass products such as glasscontainers, flat glass, and fiber insulation. Glass is made byfusing (melting) a mixture of silica (silicon dioxide; SiO2),sodium carbonate, limestone (calcium carbonate; CaCO3), andother materials. The recipe differs considerably depending


SODIUM CARBONATE

on the type of glass one wishes to make. For example, oxidesof various metals such as iron(III) oxide and copper(II) oxideare added to provide a reddish tint to the glass.

The second highest use of sodium carbonate is in theproduction of other chemical compounds, followed by thecompound’s use in the production of soaps and detergents.Other applications of the compound include:

• The production of pulp and paper products;

• The removal of sulfur dioxide from flu gases in fac-tories;

• In water purification and waste water treatment faci-lities;


• In the refining of petroleum;

• As a catalyst in the process by which coal is convertedinto a liquid fuel;

• For the bleaching of cotton and linen fabrics;

• As an emetic (a compound that induces vomiting); and

• In cosmetics and personal care products because of itsability to clean skin and help clear up rashes.

No serious health hazards have been associated with theuse of sodium carbonate in any of its forms.

Interesting Facts

• Over the last decade, con-sumption of sodium car-bonate in the UnitedStates has been decreas-ing, largely because glasscontainers (made withsodium carbonate) arebeing replaced by plasticcontainers. However, the

industry has not gone intodecline primarily becausethe demand for glass indeveloping countries con-tinues to increase at a ratethat matches the declinein glass bottle demand inthe United States.


SODIUM CARBONATE


Kiefer, David M. ‘‘Soda Ash, Solvay Style.’’ Today’s Chemist

(February 2002): 87 88+. Also available online athttp://pubs.acs.org/subscribe/journals/tcaw/11/i02/html/02chemchron.html (accessed on November 8, 2005).

Lister, Ted, compiler. ‘‘Sodium Carbonate A Versatile Material.’’Royal Society of Chemistry.http://www.chemsoc.org/pdf/LearnNet/rsc/SodiumCarb_sel.pdf (accessed on November 8, 2005).

Monet, Jefferson. ‘‘An Overview of Mummification in AncientEgypt.’’ TourEgypt.net.http://www.touregypt.net/featurestories/mummification.htm(accessed on November 8, 2005).

‘‘Soda Ash or Trona.’’ Mineral Information Institute.http://www.mii.org/Minerals/phototrona.html (accessed onNovember 8, 2005).

‘‘Sodium Carbonate.’’ United Nations Environmental Programme.http://www.inchem.org/documents/sids/sids/Naco.pdf(accessed on November 8, 2005).

See Also Sodium Bicarbonate

Words to Know







SODIUM CARBONATE

OTHER NAMES:Salt; table salt; com-

mon salt; rock salt

FORMULA:NaCl

ELEMENTS:Sodium, chlorine


ganic)

STATE:Solid




SOLUBILITY:Soluble in water and

glycerol; very slightlysoluble in

ethyl alcohol andmethyl alcohol

Sodium Chloride

KE

YF

AC

TS

OVERVIEW

Sodium chloride (SO-dee-um KLOR-ide) is a colorless towhite powder or crystalline solid with no odor and a char-

acteristic salty taste. It is slightly hygroscopic, meaningthat it tends to absorb moisture from the air and becomedamp.

Salt is probably one of the best known and most widelyused of all chemical compounds. Humans have been using

salt as a preservative and to flavor foods since the begin-ning of recorded time. One of the earliest mentions ofsodium chloride dates to 2,700 BCE in the Chinese book Peng

Tzao Kan Mu, probably the first book on pharmacology everwritten. Access to salt resources has often been a conten-

tious issue among peoples, leading to battles and wars overits ownership. It has been considered at times to be so

valuable that it was used as a form of money. Today, sodiumchloride has a host of applications beyond its use as a food

additive.

Na+ Cl-


HOW IT IS MADE

Sodium chloride occurs naturally as the mineral haliteand abundantly in the oceans, where it is found in seawaterat an average concentration of about 2.6 percent. There areseveral methods for harvesting salt, some of which date toancient times. The earliest known method of production isalso the simplest: evaporation of seawater by the Sun. In thismethod, seawater is collected in large, shallow ponds andallowed to evaporate. The salts dissolved in the water crystal-lize on the bottom of the ponds and can be scraped off andthe individual compounds present—including sodium chlor-ide—separated from each other.

This method works best in hot, arid parts of the world. Incooler, moister regions, seawater must be collected in largecontainers that can be heated artificially. In many cases, theseawater is heated under reduced pressure to allow it to boilat a lower temperature and save heating costs. Again, crys-tals of sodium chloride (and other dissolved salts) form as thewater boils away.

Perhaps the most important source of sodium chloride issalt mines, large underground reserves of sodium chlorideleft behind when ancient seas dried up and were buried bythe accumulation of rocks and soil. Salt mines are found inmany parts of the world, especially Russia, Germany, theUnited Kingdom, India, France, Mexico, Canada, and theUnited States. These mines often span many kilometers and

Sodium chloride. Turquoiseatom is sodium and green atom

is chloride. P U B L I S H E R S



SODIUM CHLORIDE

extend hundreds of meters deep. One of the most famous saltmines in the United States is located under the city ofDetroit. It contains more than 80 kilometers (50 miles) ofunderground roads built to remove blocks of sodium chlor-ide, some as wide as four-lane highways. The Detroit mineceased production in 1983 when lower salt prices and result-ing lower profits were no longer able to sustain the costs ofextraction. The Detroit mine was reopened in 1988, but onlyfor the mining of road salt.

Two methods of mining are used to remove sodium chlo-ride from underground sources. In the room-and-pillar method,shafts are dug into the deposit. Drilling and blasting are thenused to break off pieces of sodium chloride, which are removedfor processing. As mining progresses, large pillars of salt areleft standing to support the empty chambers. Thus the name:room-and-pillar. A second method of salt removal is solutionmining. A well is drilled into the ground and flooded to create asaturated solution of sodium chloride, a brine solution. Thebrine is then pumped to the surface and processed.


Probably the best known use of sodium chloride is as afood additive. The Salt Institute estimates that humans con-sume an average of 16 tons of salt during their lifetimes. Salthas long been used on foods to improve flavor and also as apreservative. Salted foods last longer than unsalted foodsbecause salt inhibits the growth of microorganisms thatcause decay.

Still, the most important use of sodium chloride by far isas a raw material in the production of other compounds. In2004, 65 percent of all the sodium chloride consumed in theUnited States was used in the production of sodium hydroxide,sodium carbonate, hydrogen chloride, sodium metal, chlorinegas, and other chemical products. The next most importantuse of sodium chloride is in water conditioners. The compoundis used in such devices because the sodium in sodium chloridewill replace the calcium and magnesium in ‘‘hard’’ water (waterin which it is hard to make suds). By softening water withsodium chloride, clothing and other materials can be cleanedmore efficiently at lower cost. The Salt Institute claims thatsodium chloride has more than 14,000 distinct uses. Some ofthe most important of those uses include:


SODIUM CHLORIDE

• As a feed additive for livestock, poultry, and otherdomestic animals, to ensure that they receive thesodium and chlorine they need to remain healthy andgrow normally;

• As a deicing product on roads and highways;

• In the manufacture of glazes used on ceramic products;

• For the curing of animal hides;

• In the dyeing and printing of fabrics;

• In the manufacture of soaps;

• As a herbicide, a chemical used to kill weeds; and

• As a fire extinguisher for certain types of fires (such asgrease fires).

Given its widespread use, sodium chloride is obviously safefor consumption by most humans under normal conditions. Aswith any chemical compound, consumption of a large excess ofsodium chloride can be harmful. The one health issue of great-est concern has to do with high blood pressure. Scientists havelearned that the ingestion of large amounts of sodium cancontribute to hypertension (high blood pressure), which in turnis associated with increased risk for heart attacks and stroke.

Interesting Facts

• Salt was a key ingredientin the solution used byancient Egyptians in thepreparation of mummies.

• The expression ‘‘not worthhis salt’’ had its origin inthe ancient Greek slavetrade, in which people werebought and sold for mea-sures of salt.

• The English word salary

comes from the Latin termsalarium argentums, whichrefers to a special salt

ration given to Roman sol-diers.

• Salt has frequently beensubject to heavy taxation;the very high tax on salt inFrance during the middleeighteenth century con-tributed to the rise of theFrench revolution.

• Salt mines that are nolonger in use are some-times used to store naturalgas and petroleum.


SODIUM CHLORIDE

The American Heart Association recommends that healthyAmerican adults consume no more than 2,300 milligrams ofsodium a day. That amount is equivalent to about a teaspoon ofsalt. For those considered at higher risk, people with highblood pressure, blacks, and middle-aged and older adults, the2005 U.S. Department of Agriculture guidelines recommend nomore than 1,500 milligrams of sodium per day. The problemwith sodium chloride consumption is that most people have noidea how much salt they eat every day. Of course, they cankeep track of the salt they add to the foods they prepare intheir own homes. But most commercially prepared foods alsohave sodium chloride added to them. In some cases, the totalamount of salt ingested from processed foods by the averageAmerican can be significant, easily exceeding the recom-mended daily average recommended by the American HeartAssociation. People can, therefore, be consuming dangerouslyhigh levels of sodium without being aware of that fact.


‘‘History of Salt.’’ The Salt Institute.http://www.saltinstitute.org/38.html (accessed on November8, 2005).

Kurlansky, Mark. Salt: A World History. New York: Walker, 2002.

‘‘Salt.’’ History for Kids.http://www.historyforkids.org/learn/food/salt.htm (accessedon November 8, 2005).

‘‘Sodium Chloride.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/S3338.htm(accessed on November 8, 2005).

‘‘What You Always Wanted to Know about Salt.’’ The Salt Institute.http://www.saltinstitute.org/4.html (accessed on November 8,2005).

See Also Chlorine; Sodium Hydroxide

Words to Know

PHARMACOLOGY The study of compoundsused as drugs.


SODIUM CHLORIDE

OTHER NAMES:Monosodium cyclo-hexylsulfamic acid;

sodium cyclohexane-sulfamate

FORMULA:C6H11NHSO3Na


nitrogen, sulfur,oxygen, sodium

COMPOUND TYPE:Organic salt

STATE:Solid




decomposes


insoluble in mostorganic solvents

Sodium Cyclamate

KE

YF

AC

TS

OVERVIEW

Sodium cyclamate (SO-dee-um SYE-kla-mate) is a white,crystal solid or powder with almost no odor and a very sweettaste. Its sweetening power is about 30 times that of tablesugar, the standard against which artificial sweeteners aremeasured. Because of its sweet flavor, sodium cyclamate isused as an artificial sweetener.

The cyclamate family of compounds was discovered in1937 by Michael Sveda (1912–1999), then a graduate studentat the University of Illinois. Sveda was working on the devel-opment of new drugs to treat fever. The story is that Svedawas smoking while he was working in the laboratory (apractice that would not be allowed today) and, at one point,he brushed some loose threads of tobacco from his lips. As hedid so, he noticed a very sweet flavor on the cigarette. Cur-ious as to the cause of the sweetness, Sveda looked morecarefully into the compounds he was studying and eventuallyidentified the source of the sweetness as a substance belongingto a class of compounds known as cyclamates. The cyclamates

H

CC

CC

C

C

Na+

NS

O

O

O-

HHH

HHH

H H

HH

H


are organic salts of the carboxylic acid cyclamic acid(C6H11NHSO3H). The University of Illinois received a patentfor the production of cyclamates, which they eventually soldto the DuPont chemical company. DuPont, in turn, sold thepatent to Abbott Laboratories, who first marketed the pro-duct in 1950. The compound rapidly became very popular asan additive for diet foods and drinks. It most formulations,it is mixed with saccharin, another artificial sweetener.Saccharin is ten times as sweet as sodium cyclamate, but it

Sodium cyclamate. Red atomsare oxygen; white atoms arehydrogen; black atoms are

carbon; blue atom is nitrogen;yellow atom is sulfur; and

turquoise atom is sodium. Graysticks indicate double bonds.



SODIUM CYCLAMATE

leaves a metallic aftertaste that sodium cyclamate helpsto mask.

The first evidence about possible health effects of ingest-ing cyclamates was announced in 1969. Scientists reportedthat they had fed eighty rats a diet that contained largeamounts of Sucaryl�, a product containing saccharin andsodium cyclamate, every day for two years. At the end ofthat time, twelve of the eighty rats had developed bladdercancer. Based on this study, the U.S. Food and Drug Admin-istration (FDA) decided to ban the use of cyclamates as foodadditives.

The FDA’s decision has long been the subject of con-siderable debate. Some people praise the agency for ban-ning a substance they believe to be carcinogenic inhumans as well as rats. Others feel that the evidence onwhich the FDA decision was based is not strong enough torequire banning of the product. In light of this contro-versy, a number of additional studies have been conductedon the health effects of the cyclamates. In 1984, the FDAreversed its decision on the compound, having becomeconvinced that no evidence had been produced to supportthe original 1969 study on which its earlier decision hadbeen made. A year later, the National Academy of Sciencesannounced the results of its own review of the evidence onthe cyclamates. The academy also saw no reason to ban theproduct as a food additive. Outside the United States, thecyclamates have generally been approved for use as anartificial sweetener.

HOW IT IS MADE

Cyclamic acid is made by the sulfonation of cyclohexyl-amine. Cyclohexylamine is a six-carbon ring compound witha single amine (-NH2) group attached to it. Its formula isC6H11NH2. Sulfonation is the process by which an -SO2 groupis added to a compound. Sulfonation of cyclohexylamine isaccomplished with either sulfur dioxide (SO2) or sulfamicacid (HOSO2NH2).


Sodium cyclamate and calcium cyclamate are used asartificial sweeteners. Since they have no nutritional value


SODIUM CYCLAMATE

(that is, the contain no calories), they can be used in foodsand drinks designed for diabetics and dieters. The productalso appeals to food processors because it is much sweeterthan table sugar. One gram of sodium or calcium cycla-mate is as sweet as 30 grams of table sugar, so much lessis needed to make a product taste sweet. The cyclamatesare also stable to heat, which means that they will notbreak down if foods in which they are contained are bakedor boiled. The compounds have long shelf lives and areinexpensive to make.

Cyclamates are often used in combination with tablesugar and other artificial sweeteners. The combination of acyclamate and saccharin, for example, has the benefit thatthe two sweeteners cancel out the bitter and metallic after-tastes that each by itself has.

Interesting Facts

• Sodium cyclamate wasnearly the undoing of thesports drink Gatorade. Thedrink was invented in thelate 1960s. The inventorsdecided to use sodiumcyclamate as a sweetenerbecause it had less of abitter aftertaste thansaccharin. One year afterGatorade first appeared,however, the FDA banned

cyclamates as foodadditives. The inventorsquickly reformulated theirproduct, using fructose inplace of cyclamates as asweetener. The drink wenton to become anoutstanding commercialsuccess, but withoutthe benefit of sodiumcyclamate.

Words to Know



SODIUM CYCLAMATE


‘‘Cyclamate.’’ Zhonga Hua Fang Da.http://www.fangda.com.hk/english/ (accessed on November 8,2005).

‘‘Low Calorie Sweeteners: Cyclamate.’’ CalorieControl.org.http://www.caloriecontrol.org/cyclamat.html (accessed onNovember 8, 2005).

‘‘Sodium Cyclamate.’’ Hazard Database.http://www.evol.nw.ru/labs/lab38/spirov/hazard/sodium_cyclamate.html (accessed on November 8, 2005).

See Also L-Aspartyl-L-phenylalanine Methyl Ester;Saccharin; Sucrose


SODIUM CYCLAMATE

OTHER NAMES:Sodium monofluoride

FORMULA:NaF

ELEMENTS:Sodium, fluorine


ganic)

STATE:Solid




SOLUBILITY:Moderately soluble in

water; insoluble inethyl alcohol

Sodium Fluoride

KE

YF

AC

TS

OVERVIEW

Sodium fluoride (SO-dee-um FLOR-ide) is a colorless towhite crystalline solid or powder. It is best known for its rolein efforts to prevent tooth decay. It may be added to tooth-pastes or mouthwashes or to municipal water supplies for thispurpose. Although the practice of fluoridating water is nowwidespread in the United States, it remains the subject ofcontroversy regarding its potential health effects on humans.

HOW IT IS MADE

Sodium fluoride occurs naturally as the mineral villiau-mite, although the compound is not produced commerciallyfrom that source. Some sodium fluoride is obtained as abyproduct of the manufacture of phosphate fertilizers. Inthat process, apatite (a form of calcium phosphate that alsocontains fluorides and/or chlorides) is crushed and treatedwith sulfuric acid (H2SO4). The products of that reactioninclude phosphoric acid (H3PO4), calcium sulfate (CaSO4),

Na+F-


hydrogen fluoride (HF), and silicon tetrafluoride (SiF4).The hydrogen fluoride and silicon tetrafluoride can then beconverted into sodium fluoride. The compound can also beproduced by treating hydrogen fluoride with sodium carbo-nate (Na2CO3):

2HF + Na2CO3 ! 2NaF + H2O + CO2


More than 50 years of research has shown that sodiumfluoride and other fluorides are effective in preventingtooth decay. Based on this information, sodium fluoride orsome other compound of fluorine is now added to mosttoothpastes made in the United States. Dentists regularlytreat their patients’ teeth with fluoride washes to makethem more resistant to decay. Most cities and towns in theUnited States add sodium fluoride or a comparable com-pound to the municipal water supply to reduce the rate ofdental caries (cavities). Some people who live where fluorideis not added to their water supply take sodium fluoridepills to improve their dental health. The American DentalAssociation and the World Health Organization recommend

Sodium fluoride. Green atomis fluorine and turquoise atom

is sodium. P U B L I S H E R S



SODIUM FLUORIDE

fluoridation of drinking water at a level between 0.7 and 1.2parts per million.

In spite of these trends, opposition to the use offluorides against tooth decay remains strong in the UnitedStates and other parts of the world. Opponents are notconvinced that there is sufficient evidence for the claimsthat fluoridation decreases the rate of tooth decay. Theysuggest that fluorides may cause cancer and a host ofother health problems. And they argue that fluoridatingpublic water supplies removes the choice that individualsshould have as to whether or not they want to use fluor-ides in their dental health program.

Sodium fluoride has a number of commercial and indus-trial uses in addition to those related to dental health. Thoseuses include:

• As a wood preservative;

• In the production of certain types of pesticides and asan insecticide for ant and roach control;

• In the preparation of other fluoride salts;

• In electroplating operations;

Interesting Facts

• Some of the oppositionto the fluoridation ofwater is based on amisunderstanding of thedifference betweenfluorine, the element,and fluorides, com-pounds of fluorine, suchas sodium fluoride andpotassium fluoride.Fluorides have verydifferent physical,chemical, and biological

properties from theelement fluorine. Forexample, fluorine gas isa highly toxic gas thatreacts violently withmost substances, includ-ing water. Flourides, onthe other hand, arerelatively inert (unreac-tive) and safe to ingestin small amounts.


SODIUM FLUORIDE

• In the degassing (removal of gas pockets) during themanufacture of steel;

• For the manufacture of glass and vitreous (glass-like)enamels;

• In detection systems for radiation in the ultraviolet andinfrared regions of the electromagnetic spectrum; and

• For disinfecting equipment used in breweries and wine-ries.

The discussion about fluoridation of public water sup-plies is sometimes made more difficult because of the factthat sodium fluoride poses some real health hazards tohumans. It is a skin, eye, and respiratory irritant that cancause burning if spilled on the skin or in the eyes. If swal-lowed, it can cause burning of the digestive tract, nausea,vomiting, abdominal pain, stupor, general weakness, tre-mors, convulsions, collapse, respiratory and cardiac failure,and death. Ingestion of as little as five grams of sodiumfluoride can result in death. A condition known as fluorosisis also associated with high doses of sodium fluoride. Fluoro-sis is characterized by a yellowing and increased brittlenessof teeth and bones. Although these conditions are all veryserious, they appear only at doses many thousands of timesgreater than one receives from fluorides in toothpastes andpublic water supplies.


‘‘Facts about Fluoride.’’ American Dental Association.http://www.ada.org/public/topics/fluoride/fluoride_article01.asp (accessed on November 8, 2005).

‘‘Fluoride in Drinking Water.’’ Science in Dispute.

Ed. Neil Schlager. Vol. 1. Detroit: Gale, 2002.

Words to Know

ELECTROPLATING A process by which a thinlayer of one metal is deposited on top of a

second metal by passing an electric cur-rent through a solution of the first metal.


SODIUM FLUORIDE

‘‘Sodium Fluoride.’’ Fluoride Action Network.http://www.flouridealert.com/pesticides/sodium fluoride page.htm (accessed on November 8, 2005).

‘‘Sodium Fluoride.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/S3722.htm(accessed on November 8, 2005).


SODIUM FLUORIDE

OTHER NAMES:Caustic soda; lye;

sodium hydrate;white caustic

FORMULA:NaOH

ELEMENTS:Sodium, oxygen,

hydrogen

COMPOUND TYPE:Base (inorganic)

STATE:Solid





ethyl alcohol, methylalcohol, and glycerol

Sodium Hydroxide

KE

YF

AC

TS

OVERVIEW

Sodium hydroxide (SO-dee-um hye-DROK-side) is a whitedeliquescent solid commercially available as sticks, pellets,lumps, chips, or flakes. A deliquescent material is one thatabsorbs moisture from the air. Sodium hydroxide also reactsreadily with carbon dioxide in the air to form sodium carbonate.Sodium hydroxide is the most important commercial caustic. Acaustic material is a strongly basic or alkaline material thatirritates or corrodes living tissue. The compound ranked number11 among chemicals produced in the United States in 2004.

HOW IT IS MADE

Sodium hydroxide is produced commercially simulta-neously with chlorine gas by the electrolysis of a sodiumchloride solution. In this process, an electric current breaksdown sodium chloride into its component elements, sodiumand chlorine. The chlorine escapes as a gas, while the sodiummetal form reacts with water to form sodium hydroxide:

H–

O–Na+


2NaCl ! 2Na + Cl2

2Na + 2H2O ! 2NaOH + H2

Sodium hydroxide can also be produced easily by meansof other chemical reactions. For example, the reactionbetween slaked lime (calcium hydroxide; Ca(OH)2) and sodaash (sodium carbonate; Na2CO3) produces sodium hydroxide:

Ca(OH)2 + Na2CO3 ! 2NaOH + CaCO3

None of these alternative methods can compete econom-ically, however, with the preparation by electrolysis.

Sodium hydroxide. Red atomis oxygen; white atom is

hydrogen; and turquoise atomis sodium. P U B L I S H E R S



SODIUM HYDROXIDE


Sodium hydroxide has a great variety of household andindustrial uses. It is the active ingredient in drain cleanerssuch as Drano� because it breaks up and dissolves the greasymass that is responsible for drain blockages. It is also aningredient in many other household products, including ovencleaners, metal polishes, and hair straighteners. Sodiumhydroxide is also used in the preparation of homemade andprocessed foods. It is used in the preparation of soft drinks,chocolate, ice creams, caramel coloring, and cocoa. Hominy, astarchy food similar to grits, is made by soaking corn kernelsin a solution of sodium hydroxide in water. Bakers glazepretzels and German lye rolls with a weak lye solution beforebaking them. The lye gives baked goods a crisp crust. Somepeople use lye to cure olives.

The largest single use for sodium hydroxide is in theproduction of organic compounds from which polymers aremade, such as propylene oxide and the ethylene amines, andof the polymers themselves, including the polycarbonatesand epoxy resins. About a third of all the sodium hydroxideproduced in the United States goes to this application.Another important use of sodium hydroxide is in the pulpand paper industry, where it is used to digest (break down)the raw materials from which pulp and paper are made.About 13 percent of all the sodium hydroxide made in the

Interesting Facts

• Solutions of sodiumhydroxide are made byadding the solid compoundto water, and never waterto the solid. The reason isthat large amounts of heatare generated whensodium hydroxidedissolves in water. Thatheat is absorbed bywater, but would not be

absorbed by solid sodiumhydroxide.

• A popular food in Scandi-navian countries, lutefisk,is made by soaking driedfish in sodium hydroxideuntil it turns into a jelly.The jelly is then soaked inwater for several days toremove the poisonous lye.


SODIUM HYDROXIDE

United States goes to this application. Sodium hydroxide isalso an important raw material in the manufacture of soap.The method by which soap is made has not changed verymuch for thousands of years. A fat or oil is added to a boilingsolution of sodium hydroxide in water. The fat or oil hydro-lyzes into its component parts, glycerol and fatty acids. Thesodium hydroxide then reacts with the fatty acids, formingsodium salts. The sodium salt of a fatty acid is a soap. Sodiumhydroxide is also an important raw material in the manufac-ture of inorganic compounds, especially sodium and calciumhypochlorite, sodium cyanide, and a number of sulfur-con-taining compounds. Some other important uses of sodiumhydroxide include:

• In the manufacture of cellophane and rayon;

• As a neutralizing agent during the refining of petroleum;

• In the manufacture of aluminum metal;

• For the refining of vegetable oils;

• As an agent for peeling fruits and vegetables for proces-sing;

• In the extraction of metals from their ores;

• For the processing of textiles;

• In water treatment facilities;

• For etching and electroplating operations; and

• In a wide variety of research laboratory applications.

Sodium hydroxide is one of the most caustic substancesknown and a strong irritant to the skin, eyes, and respiratorysystem. Exposure to sodium hydroxide dust, powder, or solidcan cause burning of the skin and eyes, with possible perma-nent damage to one’s vision. Ingestion of the compound

Words to Know

ELECTROLYSIS A process in which anelectric current is used to bring aboutchemical changes.

HYDROLYSIS The process by which acompound reacts with water to form twonew compounds.


SODIUM HYDROXIDE

causes burning of the mouth, esophagus, and stomach, result-ing in nausea, diarrhea, internal bleeding, scarring, and per-manent damage to the lungs and gastrointestinal system.More serious results, such as a drop in blood pressure andcollapse, are also possible.


‘‘Determination of Acute Reference Exposure Levels for AirborneToxicants.’’ [Sodium Hydroxide]. Office of EnvironmentalHealth Hazard Assessment, State of California.http://www.oehha.ca.gov/air/acute_rels/pdf/1310932A.pdf(accessed on November 8, 2005).

‘‘DOW Caustic Soda Solution.’’ Dow Chemical Company.http://www.dow.com/causticsoda/prod/process.htm (accessedon November 8, 2005).

‘‘Sodium Hydroxide.’’ International Chemical Safety Cards.http://www.cdc.gov/niosh/ipcsneng/neng0360.html (accessedon November 8, 2005).

‘‘Sodium Hydroxide.’’ Medline Plus.http://www.nlm.nih.gov/medlineplus/ency/article/002487.htm (accessed on November 8, 2005).

White, Elaine. ‘‘Making Modern Soap with Herbs, Beeswax, andVegetable Oils.’’http://www.pioneerthinking.com/soaps.html (accessed onNovember 8, 2005).

See Also Chlorine; Potassium Hydroxide


SODIUM HYDROXIDE

OTHER NAMES:Sodium oxychloride;hypochlorite; bleach;

chlorine bleach

FORMULA:NaClO

ELEMENTS:Sodium, chlorine,

oxygen

COMPOUND TYPE:Oxy salt (inorganic)

STATE:Solid or aqueous

solution; See Over-view


MELTING POINT:Solid NaClO explodes

on heating.The pentahydrate

(NaClO�5H2O) is morestable; its melting

point is 18�C (64�F)


decomposes


Sodium Hypochlorite

KE

YF

AC

TS

OVERVIEW

Sodium hypochlorite (SO-dee-um hye-po-KLOR-ite) is theactive ingredient in liquid chlorine bleaches, used in the homeand many industries to whiten fabric and other materials andto disinfect surfaces and water. The anhydrous compound isvery unstable and explodes readily. The pentahydrate is a pale-green crystalline solid that is relatively stable. The compoundis usually made available as an aqueous solution that containsanywhere from 3 to 6 percent sodium hypochlorite (for house-hold use) to as high as 30 percent (for industrial applications).In solution form, sodium hypochlorite is quite stable and canbe stored for long periods of time out of sunlight.

Sodium hypochlorite decomposes by two mechanisms. Inone case, it breaks down to form sodium chloride and sodiumchlorate:

3NaOCl ! 2NaCl + NaClO3

In the second case, it breaks down to form sodium chlor-ide and nascent (free single atoms) oxygen:

O

Cl–Na+


NaOCl ! NaCl + (O)

Nascent oxygen is a very active form of oxygen that isresponsible for the bleaching and disinfectant properties ofsodium hypochlorite.

Humans have long made efforts to bleach fabrics. Neithercotton nor linen, two very popular fabrics, are naturally verywhite, so efforts were made to find ways to convert them towhite materials. Those efforts were not very successful untilthe discovery of chlorine by the Swedish chemist KarlWilhelm Scheele (1742–1786) in the 1770s. The powerfuloxidizing powers of chlorine made it a likely candidate foruse as a bleach (although chemists at the time did not under-stand how bleaching occurred). The first person to take advan-tage of chlorine’s bleaching powers was the French chemistClaude Louis Berthollet (1748–1822), who lived in Javelle,France. Berthollet produced a weak solution of sodium hypo-chlorite by passing chlorine gas through sodium carbonate.The product had excellent bleaching powers, and it becameknown by the name of eau de Javelle or eau de Berthollet.

Berthollet’s invention came at just the right time. The Indus-trial Revolution was just getting under way, and the inventionof machines like the spinning jenny and the power loommechanized the commercial production of cotton and linencloth and rapidly increased the demand for bleaching agents.

HOW IT IS MADE

Sodium hypochlorite is made commercially by passingchlorine gas (Cl2) through a cold aqueous solution of sodiumhydroxide (NaOH):

Sodium hypochlorite. Redatom is oxygen; green atom ischlorine; and turquoise atom is

sodium. P U B L I S H E R S



SODIUM HYPOCHLORITE

Cl2 + 2NaOH ! NaClO + NaCl + H2O

The pentahydrate then can be extracted by crystalliza-tion.


Sodium hypochlorite is used almost exclusively for oneof two purposes: bleaching or purification. The compound isavailable commercially for household use under a number oftrade names, including Antiformin�, B-K Liquid�, Clorox�,Dakin’s Solution�, Dazzle�, Hychlorite�, Javelle water,Piochlor�, Purex�, and Saniton Toothbrush Sanitizer�.About two-thirds of the sodium hypochlorite made in theUnited States is used as a laundry bleach and sanitizer, inrestaurants and institutional kitchens for bleaching andsanitation, and for water purification in residential poolsand spas. Some examples of the ways in which sodium hypo-chlorite is used include:

• For the sterilization of milking equipment and contain-ers at dairy farms;

• For the cleaning and sterilization of work surfaces byamateur and professional beer and wine makers;

• As an ingredient in home cleaning agents, such as toiletbowl sanitizers, mold removers, and drain cleaners; and

• As a disinfectant in private water wells to prevent thegrowth of microorganisms.

About half of all the sodium hypochlorite used for indus-trial purposes is consumed in municipal and water treatmentsystems. About a third of the compound production goes tothe sterilization of municipal and commercial swimmingpools. The remaining sodium hypochlorite is used in com-mercial, municipal, and industrial cleaning and bleachingoperations.

Sodium hypochlorite is a fire and health hazard. It reactsstrongly with metals and organic materials. The rate of reac-tion increases with the concentration of sodium hypochloritein solution, so industrial and municipal formulations present agreater environmental threat than do household products. Onecombination of special concern to consumers is the reactionbetween sodium hypochlorite and compounds that containammonia. For example, the combination of household bleachand household ammonia can produce an explosive or flam-


SODIUM HYPOCHLORITE

mable mixture. The fumes from this combination can also beharmful, even deadly. Similarly, household bleach should notbe use to clean spills that contain urine since urine itselfcontains ammonia. Sodium hypochlorite is also incompatiblewith hydrogen peroxide and acidic products.

Sodium hypochlorite is an irritant to the skin, eyes, andrespiratory system. It can produce inflammation, burning,and blistering of the skin; burning of the eyes, with subse-quent damage to one’s vision; and irritation of the gastro-intestinal system that can result in stomach pain, nausea,vomiting, coughing, and ulceration of the digestive tract.

Interesting Facts

• Until the discovery ofchlorine, cloth was usuallybleached by soaking it insour milk or buttermilkand letting it sit in thesun. The process oftentook up to eight weeks andrequired large ‘‘bleachingfields’’ on which the clothcould be laid out.

• The first attempt toapply chemical principles

to the practice of bleach-ing was documented in abook on the subject bythe Scottish physicianFrancis Home, publishedin 1756. Home suggestedusing a weak solution ofsulfuric acid for bleach-ing, a practice thatreduced bleaching time toabout 12 hours.

Words to Know



OXIDATION A chemical reaction in whichoxygen reacts with some other substanceor, alternatively, in which some substance

loses electrons to another substance, theoxidizing agent.

PENTAHYDRATE A form of a crystallinecompound that occurs with five moleculesof water.


SODIUM HYPOCHLORITE


Chalmers, Louis. Household and Industrial Chemical Specialties.

Vol. 1. New York: Chemical Publishing Co., Inc., 1978.

Fletcher, John, and Don Ciancone. ‘‘Why Life’s a Bleach (The SodiumHypochlorite Story).’’ Environmental Science & Engineering.

May 1996. Also available online athttp://www.esemag.com/0596/bleach.html (accessed on November 8, 2005).

‘‘Medical Management Guidelines (MMGs) for Calcium Hypochlorite (CaCl2O2) Sodium Hypochlorite (NaOCl).’’ Agency for ToxicSubstances and Disease Registry.http://www.atsdr.cdc.gov/MHMI/mmg184.html (accessed onJanuary 12, 2006).

‘‘Sodium Hypochlorite.’’ Hill Brothers Chemical Co.http://hillbrothers.com/msds/pdf/sodium hypochlorite.pdf(accessed on November 8, 2005).

‘‘Sodium Hypochlorite.’’ Medline Plus.http://www.nlm.nih.gov/medlineplus/ency/article/002488.htm (accessed on November 8, 2005).


SODIUM HYPOCHLORITE

OTHER NAMES:Perboric acid, sodium

salt

FORMULA:NaBO3

ELEMENTS:Sodium, boron, oxy-

gen


STATE:Solid


MELTING POINT:Not available; See

Overview


SOLUBILITY:Soluble in water, with

decomposition

Sodium Perborate

KE

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AC

TS

OVERVIEW

Sodium perborate (SO-dee-um per-BOR-ate) is a white amor-phous powder commonly available as the monohydrate(NaBO3�H2O) or the tetrahydrate (NaBO3�4H2O). The most fre-quently available form of the compound, the tetraborate, is awhite crystalline solid with a salty taste that melts at 63�C(145�F) and loses its water of hydration when heated above130�C (270�F). When dissolved in water, all forms of sodiumtetraborate decompose to yield hydrogen peroxide (H2O2) andsodium borate (Na2B4O7). The formation of hydrogen peroxide,which is itself unstable and breaks down to release nascentoxygen (O), makes sodium tetraborate an excellent source of‘‘active’’ oxygen. The terms nascent and active refer to individualatoms of oxygen that have a strong tendency to react with otherelements and compounds. Since sodium tetraborate is morestable than hydrogen peroxide, it can be used for the samepurposes as the peroxide, but is safer and easier to handle.The most common applications of sodium tetraborate are indetergents, bleaches, hair care products, and disinfectants.

BO O

O-Na+


HOW IT IS MADE

Anhydrous sodium perborate can be made by heating thetetrahydrate:

NaBO3�4H2O ! NaBO3 + 4H2O

or by reacting hydrogen peroxide with sodium metaborate:

H2O2 + NaBO2 ! NaBO3 + H2O

Sodium perborate tetrahydrate is prepared by reactinghydrogen peroxide with borax (Na2B4O7).


Sodium perborates’ uses are based on the fact that it is amild and relatively safe oxidizing agent. An oxidizing agentis a substance that supplies oxygen to other substances. Theoxidation of a material may cause bleaching or the destruc-tion of disease-causing microogranisms. For example, sodiumperborate is added to some detergents to improve theirbleaching capability. It makes the detergents more effectivein removing stains, keeping white fabrics white, and preser-ving the original colors of colored cloth. The compound is

Sodium perborate. Red atomsare oxygen; yellow atom is

boron; and turquoise atom issodium. Gray sticks indicatedouble bonds. P U B L I S H E R S



SODIUM PERBORATE

also added to some automatic dishwasher powders to improvethe product’s ability to loosen left-on food and to sterilizedishes, silverware, and cookware. Sodium perborate is alsoused as an ingredient in a variety of home- and personal-careproducts, such as deodorants, mouthwashes, denture clea-ners, and toothpastes.

Sodium perborate is an irritant to the skin, eyes, andrespiratory tract. If ingested, it may cause nausea, vomiting,diarrhea, abdominal pain, and bleeding. Exposure to largequantities of the pure compound can produce severe skinrashes, permanent eye damage, breathing difficulties, uncon-sciousness, and kidney failure. Despite these concerns, peoplewho use personal- and home-care products containing sodiumperborate are at low risk for health problems. The compounddegrades during machine washing, and home users rarelyingest, inhale, or come into contact with significant quantitiesof the compound. The European Union Scientific Committeeon Toxicity, Ecotoxicity, and the Environment issued a reportin May 2004 stating that manufacturers and consumers do notneed to take steps beyond those already in place to protectthemselves from exposure to sodium perborate.


‘‘Material Safety Data Sheet.’’ Solvay Interox.http://www.solvayinterox.com.au/solvay/uploadfile/SOL030%20 %20PBST.doc (accessed on November 10, 2005).

‘‘Opinion on the Results of the Risk Assessment of Sodium Perborate.’’ Scientific Committee on Toxicity, Ecotoxicity, and theEnvironment (CSTEE), 28 May 2004.http://europa.eu.int/comm/health/ph_risk/committees/sct/documents/out225_en.pdf (accessed on November 10, 2005).

Interesting Facts

• Because of concerns aboutthe hazard that boroncompounds may pose tothe environment, sodiumperborate is being

replaced in many applica-tions by a similar but saferoxidizing agent, sodiumpercarbonate.

SODIUM PERBORATE


‘‘Sodium Perborate Information.’’ PAN Pesticides Database.http://www.pesticideinfo.org/Detail_Poisoning.jsp?Rec_Id=PC34416 (accessed on November 10, 2005).

‘‘Sodium Perborate Monohydrate.’’ Shangyuchem.http://www.chem world.com/sodium perborate.htm (accessedon November 10, 2005).

Words to Know

AMORPHOUS Without crystalline structure.


SODIUM PERBORATE


FORMULA:Monobasic: NaH2PO4;

Dibasic: Na2HPO4;Tribasic: Na3PO4

ELEMENTS:Sodium, phosphorus,

oxygen


STATE:Solid






Sodium Phosphate

KE

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AC

TS

OVERVIEW

The three forms of sodium phosphate are formed whenone or more of the three hydrogen atoms in phosphoric acid(H3PO4) are replaced by sodium atoms. When one hydrogenis replaced, the monobasic form is produced; replacing twohydrogen atoms results in the formation of the dibasic form;and replacing all three hydrogens results in the formation oftribasic sodium phosphate. All three forms of sodium phos-phate are colorless to white crystalline solids or white pow-ders. All may occur as hydrates, such as monobasic sodiumphosphate monohydrate and dihydrate (NaH2PO4�H2O andNaH2PO4�2H2O); dibasic sodium phosphate dihydrate, hepta-hydrate, and dodecahydrate (Na2HPO4�2H2O, Na2HPO4�7H2O,and Na2HPO4�12H2O); and tribasic sodium phosphate dodeca-hydrate (Na3PO4�12H2O).

The three salts are also known by a number of other names,such as: NaH2PO4: primary sodium phosphate, primary sodiumorthophosphate, sodium biphosphate, MSP; Na2HPO4: second-ary sodium phosphate, secondary sodium orthophosphate,

P

O

O3–O

O

Na+ Na+

Na+


disodium phosphate, disodium hydrogen phosphate, DSP;Na3PO4: tertiary sodium phosphate, tertiary sodium orthopho-sphate, trisodium phosphate, TSP.

HOW IT IS MADE

All forms of sodium phosphate are made by treatingphosphoric acid with a sodium compound to replace one ormore of the hydrogen atoms in the acid. For example, react-ing phosphoric acid with sodium hydroxide will make mono-basic sodium phosphate:

H3PO4 + NaOH ! NaH2PO4 + H2O

Reacting phosphoric acid with sodium carbonate willproduce the dibasic form of the compound:

H3PO4 + Na2CO3 ! Na2HPO4 + H2O + CO2

And treating phosphoric acid with an excess of sodiumhydroxide will result in the formation of the tribasic form ofthe compound:

H3PO4 + 3NaOH ! Na3PO4 + 3H2O

Sodium phosphate. Redatoms are oxygen; orange atom

is phosphorus; and turquoiseatoms are sodium. Gray sticks



SODIUM PHOSPHATE

Other methods of preparation are available for all threeforms of sodium phosphate.


The three forms of sodium phosphate have somewhatdifferent uses. Monobasic sodium phosphate is used as a foodadditive to maintain proper acidity and in baking powders, asa food supplement to provide the phosphorus needed in aperson’s daily diet, in the treatment of boiler water to reducethe formation of scale on the inner surface of the boiler, andas a feed supplement for cattle and other farm animals.

Dibasic sodium phosphate is used as a food additive tomaintain emulsions and proper acidity of food products, inthe manufacture of fertilizers, as a food supplement forhumans and farm animals, in the treatment of silk, for fire-proofing of wood and paper products, to treat boiler water, inthe production of detergents, as a raw material in the man-ufacture of ceramics, as a mordant for dyeing, and as acathartic and laxative.

Tribasic sodium phosphate is used in a variety of clean-ing agents, such as detergents, industrial cleaning products,and metal cleaners; to treat boiler water; for the tanning ofleather; in the manufacture of textiles and paper products; inthe purification of sugar; as a dietary supplement forhumans and farm animals; in paint removers; and for variousphotographic purposes.

All three forms of sodium phosphate are mild skin, eye,and respiratory system irritants. Tribasic sodium phosphatehas somewhat more serious health consequences than themonobasic or dibasic forms. Exposure to the compoundsmay produce redness, itching, burns, pain, and blisters on

Interesting Facts

• Chicken processors oftendip whole chickens in asolution of TSP beforetreating and packaging

them. The compound killsbacteria and reduces therisk of food poisoning.


SODIUM PHOSPHATE

the skin; redness, pain, and burning of the eyes; and a burn-ing sensation, coughing, shortness of breath, and a sorethroat if ingested. Taken in larger amounts, the tribasic formmay cause vomiting, nausea, and diarrhea and may induceshock and collapse. In such cases, immediate medical assis-tance is required.


‘‘Sodium Phosphate Dibasic Heptahydrate.’’ Ted Pella, Inc.http://www.tedpella.com/msds_html/19545msd.htm (accessedon November 10, 2005).

‘‘Sodium Phosphate, Monobasic.’’ Cornell University.http://msds.ehs.cornell.edu/msds/msdsdod/a9/m4481.htm#Section3 (accessed on November 10, 2005).

‘‘Sodium Phosphates.’’ Agricultural Marketing Service, U.S.Department of Agriculture.http://www.ams.usda.gov/nop/NationalList/TAPReviews/sodiumphosphates.pdf (accessed on November 10, 2005).

‘‘Trisodium Phosphate.’’ Household Products Database, NationalInstitutes of Health.http://householdproducts.nlm.nih.gov/cgi bin/household/brands?tbl=brands&id=3007033 (accessed on November 10,2005).

‘‘Trisodium Phosphate (Anhydrous).’’ International ChemicalSafety Cards.http://www.inchem.org/documents/icsc/icsc/eics1178.htm(accessed on November 10, 2005).

‘‘USDA Approves Phosphate to Reduce Salmonella in Chicken.’’Environmental Nutrition (February 1993): 3.

Words to Know

CATHARTIC A substance that promotesbowel movements.

EMULSION A temporary mixture of twoliquids that normally do not dissolve ineach other.



SODIUM PHOSPHATE

OTHER NAMES:Acrylic acid polymer

sodium salt; poly-acrylic acid sodium

salt; PAAS

FORMULA:-[-CH2-CH(COONa)-]n-


oxygen, sodium

COMPOUND TYPE:Polymer of an

organic salt

STATE:Solid





swells in water

Sodium Polyacrylate

KE

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AC

TS

OVERVIEW

Sodium polyacrylate (SO-dee-um pol-ee-AK-ruh-late) is anodorless, grainy white powder. Its most impressive property

is its ability to absorb large amounts of fluid, up to 800 timesits volume of distilled water and lesser amounts of other

liquid mixtures. This property accounts for one of its pri-mary applications, in the manufacture of disposable diapers.Diapers made from sodium polyacrylate are able to absorb up

to 30 grams of urine for each gram of diaper.

HOW IT IS MADE

Sodium polyacrylate is produced by the reactionbetween acrylic acid (H2C=CHCOOH) and its sodium salt(H2C=CHCOONa). The product of this reaction is a long-chaincopolymer consisting of alternate units of acrylic acid andsodium acrylate. A copolymer is a polymer made of twodifferent monomers, in this case, acrylic acid and sodiumacrylate. What makes this polymer different from most other

O

CNa+O C

CH

H

-H


kinds of polymers is that adjacent polymer chains are able tocross link with each other. The hydrogen on a carboxyl group(-COOH) on one chain reacts with a double bond (-C=C-) on anadjacent chain, forming a link that holds the two chainstogether. Cross-linking occurs at many points in the polymer,resulting in the formation of a mesh-like web consisting ofpolymer chains.

When water is added to the polymer, it forces carboxylgroups away from each other, forcing the mesh to open up

Sodium polyacrylate. Redatoms are oxygen; white atomsare hydrogen; black atoms are

carbon; turquoise atom issodium. Gray sticks indicatedouble bonds. P U B L I S H E R S



SODIUM POLYACRYLATE

and make space for water molecules to fill the gaps in thepolymer. As more water is added, the carboxyl groups stretcheven farther apart, making room in turn for yet more watermolecules to be absorbed by the polymer. If the polymeris allowed to dry out, water molecules leave gaps in thecompound, the empty spaces between carboxyl groupscollapse, and the polymer returns to its original size. It canthen be stored and re-used any number of times.


The primary use of sodium polyacrylate is in the manu-facture of baby diapers. The need for some sort of disposablediaper first arose during World War II because of a shortageof cotton, from which cloth diapers are made. The compoundnow has a number of other applications. For example, it isused to pack poultry, red meat, fish, fresh-cut fruits andvegetables, and fresh whole berries to keep them moist andfresh. Fluids from washing these foods during processingmay accumulate inside a package and provide an environ-ment for the growth of bacteria that cause foods to spoil.A packaging material made of cellulose and sodium polyacry-late absorbs these fluids and prevents them from beingsqueezed out of the package.

Sodium polyacrylate is also used as a thickening agent inmedical gels used to treat bed sores, which are open woundsthat develop when a person is bed-ridden for too long. Thecompound is also added to detergents and to potting soils tohelp retain water. The compound is now being used in someparts of the world where there is insufficient rain to allow

Interesting Facts

• Sodium polyacrylate wasfirst developed byresearchers for theNational Aeronautics andSpace Administration. The

material was used fordiapers worn by astro-nauts while they were onlong space trips.


SODIUM POLYACRYLATE

crops or lawns to grow. It absorbs moisture when rain doesfall and holds it in place until plants can absorb the water.

In industry, sodium polyacrylate is used in filtrationunits that remove water from airplane and automotive fuel.It is also used as a thickening agent in coatings and adhe-sives used in the upholstery, drapery, carpet, paper, paint,wallpaper, printing, and textile industries. The compound isalso used to thicken certain liquid products applied by spray-ing, such as cleaning products. Finally, it is sometimes usedto prevent fluid loss in oil wells.

Sodium polyacrylate is a mild irritant to the skin, eyes,and respiratory tract. It may cause redness, itching, and painon the skin or in the eyes; and coughing, shortness of breath,and inflammation of the respiratory tract. Questions havebeen raised about possible health effects on babies who weardisposable diapers containing sodium polyacrylate. Somepeople suggest that a baby’s tender skin may be more sensi-tive to the irritation caused by sodium polyacrylate thanthe skin of an adult. The compound was removed from tam-pons in 1985 because some women who left their tampons inplace too long experienced unacceptable levels of irritationcaused by sodium polyacrylate in the product.


Allison, Cathy. ‘‘Disposable Diapers: Potential Health Hazards?’’BCParent Online.http://www.bcparent.com/articles/baby_talk/disposable_diapers.html (accessed on November 10, 2005).

‘‘Environmental Assessment.’’ U.S. Food and Drug Administration,Center for Food Safety and Applied Nutrition.http://www.cfsan.fda.gov/~acrobat2/fnea0427.pdf (accessed onNovember 10, 2005).

Words to Know

COPOLYMER A polymer that consists of twoor more different monomers.

POLYMER A compound consisting ofvery large molecules made of one

or two small repeated units calledmonomers.


SODIUM POLYACRYLATE

Mebane, Robert C., and Thomas R. Rybolt. Plastics and Polymers.

New York: Twenty First Century, 1995.

‘‘Sodium Polyacrylate.’’ Center for Advanced Microstructures andDevices, Louisiana State University.http://www.camd.lsu.edu/msds/s/sodium_polyacrylate.htm(accessed on November 10, 2005).

‘‘Sodium Polyacrylate.’’ Flinn Scientific Company/Department ofChemistry, Iowa State University.http://avogadro.chem.iastate.edu/MSDS/Na_polyacrylate.pdf(accessed on November 10, 2005).


SODIUM POLYACRYLATE

OTHER NAMES:Sodium metasilicate;

soluble glass; waterglass

FORMULA:Varies; often repre-sented as Na2SiO3;

see Overview

ELEMENTS:Sodium, silicon, oxy-

gen


STATE:Ranges from solid to

liquid

MOLECULAR WEIGHT:Varies; sodium meta-silicate: 122.06 g/mol

MELTING POINT:Varies; sodium meta-

silicate: 1089�C(1992�F)



reacts chemicallywith hot water

Sodium Silicate

KE

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AC

TS

OVERVIEW

Sodium silicate (SO-dee-um SILL-uh-kate) is a genericterm that refers to a series of compounds with varyingproportions of sodium oxide (Na2O) and silicon dioxide(SiO2). The term is sometimes used synonymously with aspecific form of the compound called sodium metasilicate,with the chemical formula Na2SiO3. Other forms typicallyrange from Na2O�3.75SiO2 to 2Na2O�SiO2 with one or moremolecules of water of hydration. Sodium silicate is a whiteamorphous (without crystalline structure) solid with thephysical properties listed above. Other forms of sodiumsilicate range from white powders with varying degrees ofsolubility in water, to greenish, glass-like solids, to liquidswith varying degrees of viscosity. Viscosities vary over arange of nearly a million, from about 0.5 poise to more than600,000 poise. Poise is the unit of measurement for viscos-ities. Other physical properties of the sodium silicates alsovary considerably depending on the relative proportionsof sodium oxide and silicon dioxide present. The sodium

O

SiNa+ Na+O O

2–


silicates are sometimes referred to as the simplest form ofglass.

HOW IT IS MADE

Sodium silicates are made by fusing (melting) sand(silicon dioxide) and soda ash (sodium carbonate) or sodiumhydroxide in a gas-fired open hearth furnace, somewhatsimilar to the furnaces used in the manufacture of steel.The products of this reaction are lumps of sodium silicatethat are broken apart and dissolved in a stream of hotsteam. The proportions of sand and soda ash used, thetemperature of the reaction, and the amount of water thatremains in the final product all determine the physicalproperties of the final product.


About 1.1 million metric tons (1.3 million short tons) ofsodium silicate was produced in the United States in 2004.The primary application for the compound is in the manu-facture of soaps and detergents. It improves the cleaningability of these products and is less damaging to metalcomponents of dishwashers and washing machines thanother ingredients of soaps and detergents. Sodium silicate

Sodium silicate. Red atoms areoxygen; orange atom is silicon;

and turquoise atoms aresodium. Gray stick indicates

double bond. P U B L I S H E R S



SODIUM SILICATE

is also used as a water softener, used by itself or as aningredient in detergents.

The next most important applications of sodium silicateare as catalysts and in the pulp and paper industry. Catalystsare materials that increase the rate of a chemical reactionwithout undergoing any change in their own chemical struc-ture. In the pulp and paper industry, sodium silicate is usedto bleach raw pulp and help remove ink from scrap paperbeing reprocessed. The compound is also used in sealants andadhesives. Some other applications of sodium silicateinclude:

• For the purification of water in municipal and indus-trial water treatment plants;

• For the fireproofing of fabrics;

• As an anti-caking agent in food products;

• As an additive in cements, where it helps the cement setmore quickly;

• In the manufacture of other compounds of silicon bythe chemical industry;

• In fluids used to lubricate drilling instruments;

• As a liner for chemical and industrial equipment, suchas furnaces used to make steel;

Interesting Facts

• One of the early uses ofsodium silicate was as apreservative for eggs.Eggs were soaked in solu-tions of sodium silicate, orthe compound was paintedon the egg shells. Thesodium silicate filled thepore in the egg shell, pre-venting bacteria from

entering the egg andcausing it to spoil. Theprocess was very effectiveand preserved eggs for upto nine months. More effi-cient and less expensivemethods of preservingeggs are now available.


SODIUM SILICATE

• In the processing of ores from which metals areextracted; and

• As a binder on grindstones and abrasive wheels.

Sodium silicates are strong irritants to the skin, eyes,and respiratory system. Prolonged exposure to sodium sili-cate dust, powder, or liquid may cause inflammation of theskin, eyes, nose, and throat. More serious symptoms mayinclude difficulty in swallowing, burns inside the stomach,damage to the mucous membranes, rapid heartbeat, hyper-tension, shock, severe damage to the lining of the gastroin-testinal tract, various types of cancer, and death. Thesehazards are of concern primarily to workers who come intocontact with sodium silicate in solid or liquid form in theworkplace.


Higgins, Kevin T. ‘‘Simplified Food Oil Refining.’’ Food Engineer

ing (February 1, 2003). Also available online athttp://www.foodengineeringmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,6330,94941,00.html(accessed on November 10, 2005).

‘‘Practical Uses for Sodium Silicate.’’ The Chemistry Store.com.http://www.chemistrystore.com/sodium_silicate_uses.htm(accessed on November 10, 2005).

‘‘Silicate Chemistry.’’ PQ Corporation.http://www.pqcorp.com/technicalservice/understanding_silicatesolchem.asp (accessed on November 10, 2005).

‘‘Sodium Metasilicate.’’ International Programme on ChemicalSafety.http://www.inchem.org/documents/pims/chemical/

Words to Know

MUCOUS MEMBRANES The soft tissues thatline the breathing and digestive passages.

VISCOUS Describing a syrupy liquid thatflows slowly.


SODIUM SILICATE

pim500.htm#SectionTitle:1.3%20%20Synonyms (accessed onNovember 10, 2005).

‘‘Sodium Silicates.’’ Chemical Land 21.http://www.chemicalland21.com/arokorhi/industrialchem/inorganic/SODIUM%20SILICATE.htm (accessed on November10, 2005).


SODIUM SILICATE

OTHER NAMES:Disodium sulfite

FORMULA:Na2SO3

ELEMENTS:Sodium, sulfur, oxy-

gen


STATE:Solid



decomposes



slightly soluble inethyl alcohol

Sodium Sulfite

KE

YF

AC

TS

OVERVIEW

Sodium sulfite (SO-dee-um SUL-fite) is a white powder orcrystalline solid with no odor but a slightly salty taste. Thecompound is stable in dry air, but tends to decompose inmoist air to produce sulfur dioxide (SO2) and sodium hydro-xide (NaOH). The compound has a variety of uses as a foodpreservative and in the paper and pulp industry.

HOW IT IS MADE

Sodium sulfitecan beprepared by reacting sulfurdioxide,sodaash (sodium carbonate; Na2CO3), and water. The product of thisreaction is sodium bisulfite (NaHSO3), which is then treated withexcess soda ash to obtain sodium sulfite. The compound can also beobtained as a byproduct in the preparation of phenol (C6H5OH).


Sodium sulfite is an essential chemical in the pulp andpaper industry. Just over half of all the sodium sulfite made

O

SNa+ Na+O O

2–


in the United States is used by the pulp and paper industry.The compound acts as a pulping agent for wood, rags, andstraw. A pulping agent is a substance that breaks down rawmaterials and converts them into the pulp from which paperis made. Sodium sulfite is also used to remove excess chlorineused to bleach wood pulp and other raw materials needed inthe production of paper.

The second largest application of sodium sulfite is inwater and wastewater treatment plants, where it is used toreact with and neutralize excess chlorine used in the waterand wastewater treatment processes. The third most impor-tant application of sodium sulfite is in photography. Thecompound is used in the developing process, and it acts asa preservative for the final picture produced. Sodium sulfiteis still used as a food preservative also, although the condi-tions under which it can be added are somewhat limited.In addition to its hazards among individual with allergies,sodium sulfite destroys both vitamins B1 and E, meaningthat it cannot be added to foods that contain these vitamins.It is still widely used, however, in the wine-making industryfor the control of bacteria involved in the wine-makingprocess.

As noted above, a significant number of people are allergicto sodium sulfite. In addition to this health hazard, thecompound can be an irritant to the skin, eyes, and respira-tory tract. It can cause inflammation of the skin and eyes,irritation of the nose and throat, problems with breathing,and stomach upset. With the level at which most people come

Sodium sulfite. Red atoms areoxygen; yellow atom is sulfur;

and turquoise atoms aresodium. P U B L I S H E R S



SODIUM SULFITE

into contact with the compound, however, it poses littlethreat to a person’s health.


‘‘Sodium Sulfite.’’ Esseco General Chemical.http://www.genchemcorp.com/pdf/msds/Sodium%20Sulfite,%20EGC%20 %204 03.pdf (accessed on November 12, 2005).

‘‘Sodium Sulfite.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/s5066.htm (accessedon November 12, 2005).

‘‘Sodium Sulfite.’’ Solvay Chemicals.http://www.solvaychemicals.us/pdf/Sodium_Sulfite/SODSULF.pdf (accessed on November 12, 2005).

‘‘Sodium Sulfite Photographic Grade.’’ Center for Advanced Microstructures and Devices, Louisiana State University.http://www.camd.lsu.edu/msds/s/sodium_sulfite.htm (accessedon November 12, 2005).

See Also Sulfur Dioxide

Interesting Facts

• Sodium sulfite has beenused as a food preserva-tive for many years. How-ever, in 1986 the U.S. Foodand Drug Administration(FDA) banned the use ofsodium sulfites for certaintypes of food. The agencyhad discovered that aboutone in a hundred peopleare sensitive to sodiumsulfite. Thirteen deathsand more than 500 allergic

reactions resulting fromexposure to sodium sulfitehad been reported to theFDA. The agency nowprohibits the use ofsodium sulfite as apreservative on raw fruitsand vegetables. Processedfoods that contain sodiumsulfite must include anotice to that effect onthe food label.


SODIUM SULFITE

OTHER NAMES:Sodium borate;

sodium pyroborate;disodium tetraborate;

borax

FORMULA:Na2B4O7 or

Na2B4O7�10H2O; seeOverview

ELEMENTS:Sodium, boron,

oxygen


STATE:Solid

MOLECULAR WEIGHT:Na2B4O7: 201.22 g/

mol; Na2B4O7�10H2O:381.37 g/mol

MELTING POINT:Na2B4O7: 743�C

(1370�F);Na2B4O7�10H2O:

decomposes at about75�C (170�F)

BOILING POINT:Na2B4O7: 1575�C

(2867�F);Na2B4O7�10H2O: not

applicable


Sodium Tetraborate

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OVERVIEW

Sodium tetraborate (SO-dee-um tet-ruh-BOR-ate) is a termused for either the anhydrous or hydrated form of the compoundwith the formula Na2B4O7. The decahydrate (Na2B4O7�10H2O) isalso referred to as borax. Borax also occurs without water ofhydration and in that form is known as anhydrous borax.

Some historians think that borax may have been knownas long as 4,000 years ago. Since ancient people did not usethe term, however, there is considerable doubt as to theauthenticity of these claims. The compound was certainlyin use as far back as about 800 BCE when the compound wasbeing used in the Chinese and Islamic civilization for makingglass and in jewelry work. The substance was very expensive,however, and it was not widely used in Europe until theMiddle Ages. Borax became more commonly used after exten-sive deposits of its naturally occurring form were found inthe United States. The first of those deposits was discoveredin Nevada in 1879, although the largest deposits were laterfound in the desert regions of southern California. Today, the

O

O

O

ONa+ Na+

O B

BB O––O

B


largest reserves of borax are found near the town of Boron,California, and at Borax Lake, California. The compound isalso mined in Tibet, Russia, Chile, and Turkey.

Sodium tetraborate is an odorless white crystalline solidor powder. The hydrated form loses its water of hydrationwhen heated and then fuses (melts) to form a glass-like solidat higher temperatures.

HOW IT IS MADE

Sodium tetraborate occurs naturally as the mineralstincal (pronounced ‘‘tinkle;’’ Na2B4O7�10H2O) and kernite

Sodium tetraborate

decahydrate. Red atomsare oxygen; white atoms are

hydrogen; orange atomsare boron; and turquoise atoms

are sodium. P U B L I S H E R S



SODIUM TETRABORATE

(Na2B4O7�4H2O). Ores containing these minerals arecrushed, washed, and processed to obtain the decahydrateof high purity. Anhydrous sodium tetraborate can beobtained by heating the decahydrate. Sodium tetraboratecan also be obtained by processing other minerals thatcontain borates, such as ulexite (NaCaB5O9�8H2O) and cole-manite (Ca2B6O11�5H2O).


The primary use of sodium tetraborate is in the manu-facture of glass products. About 43 percent of all the com-pound used in the world goes to this application. Glass madewith sodium tetraborate is very strong and heat resistant.The well-known Pyrex� brand of glass is made with sodiumtetraborate. Today, the largest single use of borax glass isin the manufacture of fiberglass insulation and fiberglasstextiles.

The next most important use of sodium tetraborate isin the manufacture of soaps, detergents, and personal careproducts. Some well known products that contain borax

Interesting Facts

• Perhaps the best knowncommercial form ofsodium tetraborate iscalled Twenty-Mule-Team�

Borax. The name comesfrom the fact that the firstborax mines in Californiawere located 165 milesfrom the nearest train sta-tion in Mojave, California.The mined borax wastransported that distancein wagons pulled by 20mules. Each wagon cost$900 to build, weighed14,500 kilograms (32,000pounds), and had wheels 2

meters (7 feet) in dia-meter. The trip took abouttwenty days, often in tem-peratures as high as 45�C(113�F). Over the six yearsduring which mule teamswere used, about nine mil-lion kilograms (20 millionpounds) of borax weremoved from mine torailway station. In 1896 thePacific Coast Borax Com-pany (later, U.S. Borax)took the twenty-muleteams as their corporatesymbol.


SODIUM TETRABORATE

include 20-Mule-Team� Borax all-purpose cleaner, 20-Mule-Team� Borax Laundry Booster, Borateem� stain remover,and Boraxo� powdered hand soap. Some other uses of sodiumtetraborate include:

• As a flame-retardant and fungicide for wood products;

• In the production of enamel, porcelain, glazes, enamels,and frits (specialized types of glass);

• In the manufacture of fertilizers and herbicides;

• As additives for certain kinds of polymers;

• As a flux for smelting and soldering metals;

• In the preparation of rust inhibitors; and

• In certain photographic processes.

Sodium tetraborate is a mild irritant to the skin, eyes,and respiratory tract. It can cause inflammation of the skin,eyes, nose, throat, and lungs. If ingested, it can cause nausea,vomiting, diarrhea, and abdominal pain. There is some evi-dence that ingestion of sodium tetraborate can cause repro-ductive problems in laboratory animals, although similareffects have not been seen in humans. Swallowing largequantities of sodium tetraborate can have serious healthconsequences, especially for young children. The fatal doseof sodium tetraborate for young children is about five grams(0.2 ounce) of the compound.


‘‘Borax (Hydrated Sodium Borate).’’ Amethyst Galleries, Inc.http://mineral.galleries.com/minerals/carbonat/borax/borax.htm (accessed on November 12, 2005).

Words to Know

ANHYDROUS Describing a compoundthat lacks any water of hydration.

DECAHYDRATE Form of a compound thatexists with ten molecules of water.

FLUX A material that aids the processesof welding and soldering (joining) metals.



SODIUM TETRABORATE

‘‘Rio Tinto Borax.’’ Borax.http://www.borax.com/index.html (accessed on November 12,2005).

‘‘Sodium Tetraborate.’’ International Programme for ChemicalSafety.http://www.inchem.org/documents/icsc/icsc/eics1229.htm(accessed on November 12, 2005).


SODIUM TETRABORATE

OTHER NAMES:Sodium hyposulfite;

thiosulfic acidsodium salt

FORMULA:Na2S2O3

ELEMENTS:Sodium, sulfur, oxy-

gen


STATE:Solid


MELTING POINT:Decomposes at about

100�C (200�F)




Sodium Thiosulfate

KE

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OVERVIEW

Sodium thiosulfate (SO-dee-um THYE-oh-SUL-fate) is acolorless to white crystalline solid or powder with no odorand a cooling, bitter taste. The compound usually occurs inthe form of the pentahydrate (Na2S2O3�5H2O). Sodium thiosul-fate is an antichlor, a compound that reacts with and neutra-lizes excess chlorine used in some industrial, commercial, orother applications. Two other popular antichlors are sodiumbisulfite (NaHSO3) and sodium sulfite (Na2SO3). Some of themost important applications of antichlors are in the produc-tion of pulp and paper and in the textile industry. After pulp,paper, or a textile has been treated with chlorine to bleach thematerial, an antichlor such as sodium thiosulfate is added toremove any remaining chlorine from the reaction vat. Theantichlor itself is then removed by washing with water.

HOW IT IS MADE

Large amounts of sodium thiosulfate are obtained as thebyproducts of other industrial reactions, such as the production

S

S

O

O

O

Na+ Na+

2+


of sodium sulfide (NaS2) and dyes that contain sulfur. Thecompound can also be produced directly by adding powderedsulfur to a solution of sodium sulfite and heating the reactants:

Na2SO3 + S ! Na2S2O3


In addition to its use as an antichlor, sodium thiosulfate can,itself, also be used as a bleach for paper, pulp, bone, straw, ivory,and other materials. Its other major application is in photo-graphy, where it is used as a fixing agent. A fixing agent is achemical that reacts with silver bromide and silver chlorideon a photographic film that has not been exposed. The silverbromide and silver chloride are then washed away, leavingbehind and ‘‘fixed in place’’ the silver that has been producedby exposure to light. Smaller amounts of sodium thiosulfateare used for other purposes, such as:

• A food additive for the purpose of maintaining theproper of acidity of a food product or sequestering

Sodium thiosulfate. Redatoms are oxygen; yellow atomsare sulfur; and turquoise atoms

are sodium. Gray sticksindicate double bonds.



SODIUM THIOSULFATE

(capturing and holding) unwanted materials in thefood;

• For certain medical purposes, such as the treatment offungal infections of the skin in humans and, specifi-cally, for the treatment of ringworm in animals;

• In hide tanning and dyeing procedures that use com-pounds of the element chromium;

• For the extraction of silver metal from its ores; and

• In the analysis of the composition of chemical mix-tures.

Sodium thiosulfate is an irritant to the skin, eyes, andrespiratory tract, although such effects tend to be mildunless one is exposed to large quantities of sodium thiosul-fate dust, mist, or solutions. The compound can also be toxicif ingested, causing irritation of the gastrointestinal tract.The amount of sodium thiosulfate permitted in foods is 0.1percent. No serious long-term effects of exposure to thecompound are known.

Interesting Facts

• An important, but seldomused, application ofsodium thiosulfate is

as an antidote for cyanidepoisoning.

Words to Know

ANTICHLOR A chemical that reacts withexcess chlorine used for purification,disinfecting, or some other purpose.


SODIUM THIOSULFATE


‘‘Sodium Thiosulfate.’’ Esseco General Chemistry.http://www.genchemcorp.com/pdf/msds/Sodium%20Thiosulfate,%20EGC%20 %204 03.pdf (accessed on November 12, 2005).

‘‘Sodium Thiosulfate, Pentahydrate.’’ Boehringer Ingelheim.http://www.boehringer ingelheim.ca/vetmedica/msds_sodium.asp(accessed on November 12, 2005).

‘‘Sodium Thiosulfate (Systemic).’’ Drugs.com.http://www.drugs.com/cons/Sodium_Thiosulfate.html (accessedon November 12, 2005).

See Also Sodium Sulfite


SODIUM THIOSULFATE

OTHER NAMES:Tin(II) fluoride; tin

difluoride

FORMULA:SnF2

ELEMENTS:Tin, fluorine


ganic)

STATE:Solid





insoluble in ethylalcohol, ether, and

chloroform

Stannous Fluoride

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OVERVIEW

Stannous fluoride (STAN-us FLOR-ide) is a lustrous, whitecrystalline solid with a salty and bitter taste. The only appli-cation of any consequence for stannous fluoride is as anadditive in toothpastes. Its function is to strengthen toothenamel and reduce the rate of tooth decay.

The first hints that fluorides might be helpful in prevent-ing tooth decay were reported as early as 1901. Fluorides arebinary compounds of the element fluorine, compounds con-taining one element other than fluorine. Sodium fluoride(NaF), potassium fluoride (KF), and stannous fluoride are typi-cal fluorides. But solid scientific evidence for the role offluorides in preventing tooth decay was not available untilthe 1940s. Even then, the idea of adding fluorides to tooth-pastes to reduce the risk of tooth decade was hampered byresearchers’ inability to find suitable fluoride compounds touse for this purpose. One research team working on thisproblem was that of Joseph C. Muhler (1923–1996), then anundergraduate student at Indiana University, and one of his

F–Sn2+F–


instructors, Harry G. Day (1906– ). Muhler and Day discoveredthat stannous fluoride was significantly more effective atpreventing cavities than other fluorides they had tested.Furthermore, the compound could be incorporated into tooth-pastes without affecting their other properties. Their firstresearch paper on the subject was published in 1950. Theinformation discovered by Muhler and Day was sold to theProctor & Gamble company, which released the first tooth-paste containing stannous fluoride—Crest�—in 1955.

HOW IT IS MADE

Stannous fluoride is made commercially by reacting stan-nous oxide (SnO) with hydrofluoric acid (H2F2) in an oxygen-free environment.


The primary use of stannous fluoride is in toothpastes,dental rinses, and fluoride treatments for teeth. Fluoridesprevent tooth decay in two ways. First, fluorides kill bacteriathat cause tooth decay. Second, fluorides react with otherchemicals in the mouth to make new enamel to replaceenamel destroyed by bacteria or worn away by mechanicalprocesses. Studies suggest that stannous fluoride also hasother beneficial effects, including preventing gingivitis(inflammation of the gums) and bad breath.

Stannous fluoride does have some disadvantages as anadditive in tooth care products. For example, it has asomewhat bitter and unpleasant taste. Today, a number of

Stannous flouride. Greenatoms are tin and turquoise

atom is flourine. P U B L I S H E R S



STANNOUS FLUORIDE

alternatives have been developed for stannous fluoride as anadditive in dental products. The most successful of thesealternatives is sodium monofluorophosphate (MFP), whichis now the most popular anti-decay additive in toothpastes.Some research suggests that another compound, stannoushexafluorozirconate, may be even more effective than eitherstannous fluoride or MFP as a decay preventive compound.

Stannous fluoride is a classic example of a compoundthat must be used in moderation. In small concentrations,it appears to be completely safe for human uses. In largerdoses, it may have some health risks. For example, inconcentrations of more than two parts per million, stan-nous fluoride (and other fluorides) may causes fluorosis, amottling (brownish coloring) of the teeth and changes inbone composition. Individuals who work with pure stan-nous fluoride may also be at risk from exposure to itspowder or dust. It is an irritant and may cause inflamma-tion of the skin, eyes, or respiratory system. Symptomsmay include coughing, wheezing, and shortness of breath.These effects do not occur, however, at the level at whichstannous fluoride occurs in tooth care products.


‘‘How Crest Made Business History.’’ Working Knowledge, HarvardBusiness School.http://hbswk.hbs.edu/item.jhtml?id=4574&t=bizhistory(accessed on November 15, 2005).

Interesting Facts

• The effects of fluorides inpreventing tooth decaywere first observed by ayoung dentist named Fre-derick S. McKay in Color-ado Springs, Colorado, in1901. McKay noticed thatmany of his patients hadunattractive brown stainson their teeth. But the rate

of tooth decay amongthese patients was verylow. He concluded thatboth the brown stains andthe low rate of tooth decaywere caused by unusuallyhigh levels of fluorides inthe local water supply.


STANNOUS FLUORIDE

McCoy, Mike. ‘‘What’s That Stuff: Fluoride.’’http://pubs.acs.org/cen/whatstuff/stuff/7916sci4.html(accessed on November 15, 2005).

‘‘Stannous Fluoride.’’ International Programme for ChemicalSafety.http://www.intox.org/databank/documents/chemical/stanflur/eics0860.htm (accessed on November 15, 2005).

Walter, Patricia A. ‘‘Dental Hypersensitivity: A Review.’’ The Jour

nal of Contemporary Dental Practice (May 15, 2005): 107 117.

See Also Sodium Fluoride


STANNOUS FLUORIDE

OTHER NAMES:Ethylbenzene;

vinylbenzene; pheny-lethylene; styrol;

styrolene; cinnamol

FORMULA:C6H5CH=CH2


COMPOUND TYPE:Aromatic hydrocar-

bon (organic)

STATE:Liquid





soluble in ethylalcohol and acetone

Styrene

KE

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AC

TS

OVERVIEW

Styrene (STY-reen) is a colorless to yellowish, oily liquidwith a sweet, flowery odor at low concentrations and a sharp,penetrating, disagreeable odor at high concentrations. When

exposed to light and air, it slowly polymerizes. Polymeriza-tion is the chemical reaction in which a small molecule, such

as styrene, reacts with other molecules of the same kind toproduce very large molecules, usually made of long chains.

Styrene occurs naturally in very small amounts in certainfoods, such as coffee, strawberries, and cinnamon; in the sap

of some trees; and in the gaseous emissions from internalcombustion engines, waste incinerators, and tobacco smoke.

HOW IT IS MADE

The first step in the preparation of styrene involves thereaction between benzene (C6H6) and ethylene (ethene;CH2=CH2), resulting in the formation of ethylbenzene(C6H5CH2CH3). The ethylbenzene is then dehydrogenated

C

CC

C

C

C C

H

H

H H

HC

H H

H


over a catalyst of iron(III) oxides at temperatures of about600�C (1100�F). Dehydrogenation is the process by whichhydrogen atoms are removed from a compound:

C6H5CH2CH3 - H2 ! C6H5CH=CH2


About two-thirds of all the styrene produced in the UnitedStates is used in the manufacture of polystyrene. Polystyreneis a clear, colorless, hard plastic that is easily molded andmade into a foam known as styrofoam. It is used in the insula-tion of electrical wires and devices, in containers for hot andcold foods and drinks, and for the insulation of buildings.

Styrene. White atoms arehydrogen and black atoms arecarbon. Gray stick indicatesdouble bond; striped sticks

show benzene ring.P U B L I S H E R S R E S O U R C E G R O U P


STYRENE

Almost all of the remaining styrene is used in the production ofother polymers, such as acrylonitrile-butadiene-styrene resins,styrene-acrylonitrile resins, styrene-butadiene rubber andlatex, and various polyester resins.

The styrene fumes to which a person might be exposedare mild irritants to the skin, eyes, and respiratory tract.They may cause inflammation of the skin, eyes, nose, andthroat. In larger amounts, they may adversely affect thenervous system causing nausea, tiredness, muscle weakness,depression, and concentration problems. Adequate studies onthe carcinogenic properties of styrene have not been con-ducted, but the International Agency for Research on Cancerhas called styrene a possible carcinogen. There are also nostudies on the possible reproductive effects of exposure tostyrene. In any case, the individuals most at risk for thehealth hazards of styrene are people who come into contactwith the chemical in the workplace.

Styrene is also a moderate fire risk. In certain concentra-tions, it is also explosive. Again, these risks are of concernprimarily to individuals who work with the pure compoundin their jobs.

Interesting Facts

• In 2004, about 5.4 millionmetric tons (5.9 millionshort tons) of styrene wereproduced in the United

States. It ranked 17thamong all chemicalsproduced that year.

Words to Know


RESIN A natural or artificial soft solidmaterial that is used as glue, ink, orin various plastics.


STYRENE


‘‘Material Safety Data Sheet: Styrene Monomer, Inhibited.’’ Department of Chemistry, Iowa State University.http://avogadro.chem.iastate.edu/MSDS/styrene.htm(accessed on November 15, 2005).

‘‘Styrene.’’ International Chemical Safety Cards.http://www.cdc.gov/niosh/ipcsneng/neng0073.html (accessedon November 15, 2005).

‘‘Styrene.’’ National Safety Council.http://www.nsc.org/library/chemical/styrene.htm (accessed onNovember 15, 2005).

The Styrene Information and Research Center.http://www.styrene.org/ (accessed on November 15, 2005).

‘‘ToxFAQs for Styrene.’’ Agency for Toxic Substances and DiseaseRegistry.http://www.atsdr.cdc.gov/tfacts53.html (accessed on November15, 2005).

See Also Polystyrene


STYRENE

OTHER NAMES:Saccharose; table

sugar; beet sugar;cane sugar

FORMULA:C12H22O11


oxygen

COMPOUND TYPE:Carbohydrate; disac-

charide (organic)

STATE:Solid


MELTING POINT:185.5�C (365.9�F);

begins to decomposeat about 160�C

(320�F)



slightly soluble inethyl alcohol

Sucrose

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OVERVIEW

Sucrose (SUE-krose) is a white crystalline solid or powderwith no odor but a characteristic sweet taste. It is the mostwidely used sweetener in the world. When heated, it tends todecompose, breaking down into carbon and water. The pre-sence of carbon accounts for the increasing dark color of thecompound as it caramelizes (changes from sucrose to cara-mel).

Sucrose is a disaccharide, a carbohydrate that consists oftwo monosaccharides. The carbohydrates are a large familyof organic compounds that contain carbon, hydrogen, andoxygen, the latter two in a ratio of about two to one (as isthe case with water). Thus the name ‘‘carbo-hydrate.’’ Somefamiliar monosaccharides are glucose, fructose, and galac-tose; while the disaccharides include sucrose, maltose (maltsugar), and lactose (milk sugar). Sucrose molecules consist ofa molecule of glucose joined to a molecule of fructose.

The use of sugar is thought to have originated in Poly-nesia, from where it later spread to India. Probably the first

OH

OH

HO

HH

HH

H H

H H

H

H

H

C

C

O

C C O

CC

OH OH

OH

OH

OH

C C

C CC

O

H

CH

H


recorded reference to sugar dates to 510 BCE when the Persianemperor Darius referred to sugar cane growing on the banksof the Indus River as ‘‘the reed which gives honey withoutbees.’’ Knowledge of sugar later spread across Asia into NorthAfrica, but reached Europe only in the eleventh century.Warriors returning from the Crusades brought back storiesabout a new spice with a very pleasant flavor. Since growingsugar cane in Europe was difficult, the ‘‘new spice’’ was diffi-cult to obtain and very expensive.

The sugar cane plant was brought to the New World onthe earliest voyages of Christopher Columbus. His crewfound that the plant grew easily in the congenial climate ofthe West Indies, and it rapidly became one of the most

Sucrose. Red atoms areoxygen; white atoms

are hydrogen; and black atomsare carbon. P U B L I S H E R S



SUCROSE

important crops cultivated by Europeans. Indeed, someauthors have observed that the profits from sugar exporta-tion to Europe far exceeded the vast treasurers of gold forwhich early explorers searched, and never found.

HOW IT IS MADE

Sucrose occurs naturally in a number of plants, primarilysugar cane and sugar beets. Sugar cane is the source of about70 percent of the world’s sucrose, and sugar beets account forthe remaining 30 percent. Small amounts of sucrose are alsoobtained from sugar maple trees and sorghum, a cereal graincrop.

The process of making sugar depends on the source fromwhich it is extracted. With sugar cane, the plant stalks arecrushed to obtain the sweet juice they contain. The juice istreated with lime to remove impurities and then boiled untilthe juice thickens into a syrup. Evaporation of the syrupproduces crystals of sucrose. Juice remaining after the evapora-tion step is sold as molasses. Stalks remaining after the juicehas been extracted can be used as a fuel in the plant’s boilers.

Sugar beets are harvested in the fields, washed, and cutinto small pieces. The beet chips are then soaked in waterand pressed to extract the sweet juice in them. The juice isboiled and the liquid evaporated to obtain crystalline sucrose.The solid material remaining from this process can be usedas animal feed.


Sucrose is used almost entirely for human consumptionin one form or another. The compound has two importantfunctions. First, its sweet flavor makes foods more palatableand pleasant to eat. Second, its digestion results in therelease of energy used by the body for growth, development,and everyday activities. When sucrose is digested, it firstbreaks down into the monosaccharides of which it is com-posed, glucose and fructose, with the release of energy storedin chemical bonds. Next, each of these monosaccharides isitself digested, resulting in the formation of carbon dioxide,water, and additional energy for body functions.

Sucrose is available in many forms, ranging from cubesto crystalline granules to finely ground sugar to powdered


SUCROSE

sugar. All forms of sucrose have identical chemical and bio-logical properties. Impure forms of sugar are also available.Brown sugar, for example, contains small amounts ofmolasses that are not removed during the sugar refiningprocess.

Sucrose is used as a food additive in an almost unlimitedvariety of food products, including jams and jellies, candies,cakes and pies, ice cream and sherbet, and all types of cannedand frozen foods. It serves a number of purposes in processedfoods, including:

• To add sweetness to foods;

• As a preservative in jams and jellies;

• To increase the boiling point or reduce the freezingpoint of foods;

• To make possible the fermentation of foods by yeast;

• To improve the color or flavor of certain food products;

• As a demulcent, a substance that soothes the mucousmembranes; and

• To add crispness to food products that do not havesufficient natural moisture.

Sucrose also has a limited number of industrial applica-tions unrelated to the food industry. It is used in the produc-tion of some plastics, such as rigid polyurethane foams, inthe manufacture of inks, and in the production of some typesof soap.

Interesting Facts

• Early European physiciansrecommended sugar forthe treatment of diseases.Both Buddha and Moham-mad suggested its use as amedicine.

• The alcoholic drink rumwas first produced in theWest Indies in the early

sixteenth century by thedistillation of sugar juice.Rum was first considered adrink suitable only forcommon people, but even-tually spread to Europeand became popularamong the upper classesas well.


SUCROSE

Consumed in moderate amounts, sucrose poses no healthhazards to humans or other animals. Eating excessiveamounts of sucrose, however, is related to a number of healthproblems, most important, dental caries (tooth decay) andobesity. Sucrose is an important factor in the developmentof tooth decay because it provides the primary nutrientneeded by bacteria living in the mouth. Cleaning one’s teethregularly is the best single way of preventing dental cariescaused by the consumption of sucrose. Obesity is a problemthat develops when a person consumes more foods thanneeded for normal healthy body function. When those foodsare not utilized by the body, they are stored as fatty deposits,resulting in obesity and a number of health problems relatedto it, such as diabetes and heart disease.


Mardis, Anne L. ‘‘Current Knowledge of the Health Effectsof Sugar Intake.’’ Family Economics and Nutrition Review

(Winter 2001): 88 91. Also available online athttp://www.cnpp.usda.gov/FENR/FENRv13n1/fenrv13n1p87.pdf.

‘‘Sucrose.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/s7394.htm(accessed on November 15, 2005).

‘‘Sugar. Sweet by Nature.’’ The Sugar Association.http://www.sugar.org/ (accessed on November 15, 2005).

‘‘Welcome to the World of Sugar Technology.’’ Sugar KnowledgeInternational.http://www.sucrose.com/ (accessed on November 15, 2005).

‘‘What Is Sugar?’’ The Accidental Scientist.http://www.exploratorium.edu/cooking/candy/sugar.html(accessed on November 15, 2005).

See Also Fructose; Glucose; Lactose; Sucrose Polyester


SUCROSE

OTHER NAMES:Sucrose octaoleate;

sucrose ocatester

FORMULA:See Overview


oxygen

COMPOUND TYPE:Polyester (organic)

STATE:Liquid or solid





soluble in manyorganic solvents

Sucrose Polyester

KE

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OVERVIEW

Sucrose polyester (SUE-krose pol-ee-ESS-ter) is an artifi-cial fat available under the trade names of Olestra� orOlean�. The sucrose polyester molecule is quite large andcannot be absorbed or digested by the human digestive sys-tem. Since it cannot be digested, it provides no calories toone’s diet. The compound is used primarily as an additive insnack treats targeted at people on a diet.

Sucrose polyester is one of many compounds developedby researchers in an effort to reduce the caloric intake ofpeople trying to lose weight. Artificial sweeteners designedfor this purpose include saccharin, cyclamates, aspartame,and acesulfame K. Sucrose polyester is probably the bestknown and most successful artificial fat produced so far. Itwas developed in the late 1960s by two researchers at Procter& Gamble’s Miami Valley Laboratories, Robert Volpenheinand Fred Mattson. Volpenhein and Mattson were lookingfor a new kind of fat that could be digested more easilyby premature babies. Instead, they made a very different


discovery: a compound that has many of the properties of afat (including its flavor), but that passes through the diges-tive system without being absorbed or digested. Companyexecutives immediately saw the practical application of the

Sucrose octaoleate. Red atoms areoxygen; white atoms are hydrogen; andblack atoms are carbon. P U B L I S H E R S



SUCROSE POLYESTER

new compound for dieters and began a program for gainingfederal approval for its use as a food additive.

The regulatory history of sucrose polyester has been verycomplicated, however. It was not until 1987 that Procter &

Gamble had gained enough research evidence to submitsucrose polyester to the U.S. Food and Drug Administration(FDA) for its approval. Then, it took another ten years for theFDA to act on (and approve) Procter & Gamble’s application.Even then, FDA approval was limited to certain specializedkinds of foods, including potato chips, crackers, and tortillachips. The FDA’s action has not been repeated in many othercountries, however. For example, the United Kingdom hasnever approved the use of sucrose polyester as a food addi-tive in that nation.

In fact, Procter & Gamble has faced a number of obsta-cles in marketing products made with sucrose polyester. Anumber of questions have been raised about possible healtheffects of the compound, and very few products containingsucrose polyester are currently available in the marketplace.

HOW IT IS MADE

Sucrose is a molecule that has eight hydroxyl (-OH) groupsin it. For that reason, it can be thought of as a polyol. A polyolis an alcohol with two or more hydroxyl groups. A character-istic reaction of alcohols is that they react with acids to formesters. As a simple example, the reaction between acetic acidand ethanol produces the ester ethyl acetate:

CH3COOH + CH3CH2OH ! CH3COOCH2CH3 + H2O

Since sucrose has eight hydroxyl groups, it can reactwith up to eight acids to form somewhat complex esters.Sucrose polyester is a compound formed by this method. Itis typically made by reacting six to eight of its hydroxylgroups with long-chain acids known as fatty acids. Youcan see what the resulting compound is called a polyester,that is, sucrose with many ester groups on it. As theirnames suggest, fatty acids are acids obtained from fats.A typical fatty acid is palmitic acid, which has the formulaCH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2

COOH.

Perhaps you can imagine what a molecule of sucrosepolyester looks like. It has the basic structure of sucrose


SUCROSE POLYESTER

with six to eight fatty acids attached to it. The molecule isvery large and cumbersome. No wonder the digestive systemis unable to break it down!

A number of methods are available for reacting all ormost of the hydroxyl groups in sucrose with fatty acids. Inone method, the hydroxyl groups are first reacted with amuch simpler acid, acetic acid (CH3COOH), forming sucroseoctaacetate (octa ¼ ‘‘eight’’). The sucrose octaacetate is thenreacted with a compound that has fatty acid fragments in it,such as methyl palmitate. The sucrose octaacetate is con-verted to sucrose polyester.


Procter & Gamble had high hopes for Olestra when it wasfirst introduced to the marketplace in the late 1990s. Publicreaction was very positive at first. However, enthusiasm forthe new product began to die off rather quickly. Olestra-containing products earned the company $400 million in1998, but only two years later, sales had dropped to $200million. One concern is that Olestra may have undesirablehealth effects on some individuals. These effects includebloating, diarrhea, cramps, loose stools, and urgency of defe-cation. The compound also appears to interfere with theabsorption of certain vitamins. When the FDA approvedOlestra for use in the United States, it added the requirementthat vitamins A, D, E, and K also be added to counteract thiseffect. The future status of sucrose polyester is, at this point,somewhat in doubt.

Interesting Facts

• The first commercial pro-duct in the United Statesto contain Olestra was theFrito Lay WOW brand ofpotato chips.

• One ounce of potato chipsmade with Olestra has 75calories and no fat; by com-parison, an ounce of regularpotato chips have 150 cal-ories and 10 grams of fat.


SUCROSE POLYESTER


‘‘A Brief History of Olestra.’’ Center for Science in the PublicInterest.http://www.cspinet.org/olestra/history.html (accessed onNovember 15, 2005).

‘‘Fat Replacers: Olestra.’’ College of Agricultural Sciences, Pennsylvania State University.http://pubs.cas.psu.edu/FreePubs/pdfs/uk058.pdf (accessed onDecember 29, 2005).

‘‘Pass the Potato Chips!’’ Vanderbilt University.http://www.vanderbilt.edu/AnS/psychology/health_psychology/olestra.htm (accessed on November 15, 2005).

‘‘Welcome to Olean Brand Olestra.’’ Procter & Gamble.http://www.olean.com/ (accessed on November 15, 2005).

See Also Sucrose


SUCROSE POLYESTER

OTHER NAMES:Sulfurous oxide; sul-

furous anhydride

FORMULA:SO2

ELEMENTS:Sulfur, oxygen


(inorganic)

STATE:Gas





ethyl alcohol, ether,and chloroform

Sulfur Dioxide

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OVERVIEW

Sulfur dioxide (SUL-fur dye-OK-side) is a colorless gaswith a sharp, harsh odor similar to that of a burning match.It can act as both an oxidizing agent and a reducing agent.An oxidizing agent is a substance that provides oxygen toother substances or provides electrons to them. A reducingagent removes oxygen from other substances or removeselectrons from them. Sulfur dioxide dissolves readily inwater, forming sulfurous acid (H2SO3), which is readily con-verted to sulfuric acid (H2SO4).

Sulfur dioxide is a natural component of air. It is producedwhen trees, brush, and other organic matter burn, and it ispresent in volcanic gases. It is also released during the normalmetabolic reactions of some living organisms, especially mar-ine plankton and bacteria. The compound is also produced inlarge amounts by human activities. All fossil fuels (coal, oil,and natural gas) contain small amounts of sulfur as impurities.When those fuels burn, the sulfur they contain is converted tosulfur dioxide, which becomes a component of air pollution.

S

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HOW IT IS MADE

Sulfur dioxide can be prepared by several methods, themost common of which is the combustion of sulfur or pyrites(FeS2). A variety of furnaces have been developed for carry-ing out this reaction. Each type of furnace produces sulfurdioxide of different purities. After production, the sulfurdioxide is normally cooled and compressed to convert it toliquid form. Liquid sulfur dioxide is more easily stored andtransported than the gaseous form. Sulfur dioxide is alsoobtained as the byproduct of a number of industrial opera-tions, especially the smelting of metallic ores. Smelting isthe process by which a metal is extracted from its ore byheating in air. Since many ores are sulfides, this processoften results in the formation of sulfur dioxide, which canbe captured as a byproduct of the operation. Finally, sulfurdioxide can be produced by the direct combustion of sulfuritself:

S + O2 ! SO2


About 45 percent of all the sulfur dioxide produced in theUnited States is used in the manufacture of other chemicalcompounds, the most important of which is sodium bisulfite(NaHSO3). Other compounds made from sulfur dioxide includesulfuric acid (H2SO4), chlorine dioxide (ClO2), sodium dithio-nate (Na2S2O6�2H2O), and sodium thiosulfate (Na2S2O3�5H2O).Sulfur dioxide is also used as a bleaching agent for a numberof products, including pulp and paper, textile fibers, straw,glue, gelatin, starches, grains, and various oils. The compound

Sulfur dioxide. Red atoms areoxygen and yellow atom is

sulfur. P U B L I S H E R S R E S O U R C E

G R O U P


SULFUR DIOXIDE

has a number of agricultural uses, especially in the treat-ment of soybeans and corn to destroy molds and preservethe product from decay. It is also used in the processing andrefining of metal ores and petroleum. For example, it isadded to some petroleum products to remove dissolved oxy-gen that would cause rust of pipes through which the pro-ducts are distributed. Some other applications of the com-pound include:

• As a preservative for certain dried fruits and vegeta-bles, such as cherries and apricots;

• As an additive in beers to prevent the formation ofharmful products known as nitrosamines;

• As an additive in wines to prevent the growth of unde-sirable molds and other fungi;

• In the production of high-fructose corn syrups (HFCS)used as sweeteners in commercial food and drink pro-ducts;

• As an antichlor in water purification systems;

• In the refining of sugar;

• In the manufacture of certain clay products to counter-act the presence of compounds or iron and other metalsthat would impart color to the final product;

Interesting Facts

• Sulfur dioxide was firststudied in detail by theEnglish physicist andchemist Joseph Priestley(1733–1804), who inventeda method for collectinggases over water.

• The ancient Greeks andRomans fumigated theirhomes by burning sulfur.The sulfur dioxide formed

destroyed microorganismsthat cause disease and rot.

• The concentration ofsulfur dioxide in clean airabove the continents isless than one part perbillion. Volcanic eruptionsaccount for about half ofall the gas produced bynatural sources.


SULFUR DIOXIDE

• In the molding and casting of magnesium parts andproducts; and

• In the sulfonation of oils, an important chemical processby which a sulfate group (-SO3) is added to a compound.

Sulfur dioxide is a very toxic gas that can be an irritantto the eyes, the respiratory system, and, in some cases, theskin. At concentrations normally found in ambient air (thetypical atmospheric environment surrounding us), theseeffects are annoying, but not particularly dangerous. Suchis not the case for individuals with respiratory disorders, theyoung, or the elderly. Such individuals may experience moreserious breathing problems that require medical attention.Higher concentrations of the gas may cause more seriousproblems, such as coughing, headache, dizziness, feelingsof suffocation, and nausea. These conditions are most likelyto occur in areas where air pollution is a problem, as in urbanor industrial areas. People who are constantly exposed torelatively high concentrations of sulfur dioxide (such assmelter workers) may experience more serious long-termhealth problems, such as asthma, chronic bronchitis, lungdisease, or emphysema.

The health effects of sulfur dioxide are serious enoughthat the compound is not allowed as a food additive in meatsand other food products that contain vitamin B1. The reasonis that sulfur dioxide reacts with and destroys the vitamin.The U.S. Environmental Protection Agency (EPA) has deter-mined that humans should not be exposed to a concentrationof more than 0.030 parts per million on average throughoutthe year, or more than 0.14 parts per million over any one24-hour period.

In addition to its health effects on humans, sulfur dioxidehas some important consequences for the physical and biolo-gical environment. Those effects occur because sulfur dioxidereleased to the atmosphere from electricity-generating plantsand factories combines with moisture in the air to formsulfuric acid. Sulfuric acid then falls to earth in the form ofacid rain, acid snow, or some other form of acid precipitationwhere it damages buildings and other structures, trees andother plant life, and fish and other aquatic organisms. Since1995, the EPA has sponsored a variety of control programsdesigned to reduce the release of sulfur dioxide into theatmosphere to prevent such problems.


SULFUR DIOXIDE


‘‘Acid Rain Program.’’ U.S. Environmental Protection Agency.http://www.epa.gov/airmarkets/arp/ (accessed on November15, 2005).

‘‘SO2 How Sulfur Dioxide Affects the Way We Live & Breathe.’’Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency. November 2000. Also availableonline athttp://www.epa.gov/air/urbanair/so2. (accessed on November15, 2005).

‘‘Sulfur Dioxide.’’ Air Liquide.http://www.airliquide.com/en/business/products/gases/gasdata/index.asp?GasID=27 (accessed on November 15, 2005).

‘‘Sulfur Dioxide.’’ New Jersey Department of Health and SeniorServices.http://www.state.nj.us/health/eoh/rtkweb/1759.pdf (accessedon November 15, 2005).

‘‘ToxFAQs for Sulfur Dioxide.’’ Agency for Toxic Substances andDisease Registry.http://www.atsdr.cdc.gov/tfacts116.html (accessed on November15, 2005).

See Also Sodium Sulfite; Sulfuric Acid

Words to Know

ANTICHLOR A chemical that reacts withexcess chlorine used for purification,disinfecting, or some other purpose.

METABOLISM All of the chemical reactionsthat occur in cells by which fats, carbohy-

drates, and other compounds are brokendown to produce energy and the com-pounds needed to build new cells andtissues.


SULFUR DIOXIDE

OTHER NAMES:Hydrogen sulfate; oil

of vitriol

FORMULA:H2SO4

ELEMENTS:Hydrogen, sulfur,

oxygen

COMPOUND TYPE:Acid (inorganic)

STATE:Liquid




SOLUBILITY:Completely miscible

with water

Sulfuric Acid

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OVERVIEW

Sulfuric acid (sul-FUR-ik AS-id) is a colorless to darkbrown, dense, oily liquid that mixes completely with water.Its color depends on its purity, with compounds of sulfuradding a darker color to the colorless pure product. Sulfuricacid is also available in a form known as fuming sulfuricacid, a solution of sulfur trioxide in sulfuric acid with thechemical formula xH2SO4�ySO3. Sulfuric acid is the mostcommonly manufactured chemical in the world. In 2004,the chemical industry produced 37,515,000 metric tons(41,266,000 short tons), of which more than half was usedin the manufacture of fertilizers.

Some historians credit the discovery of sulfuric acid tothe Islamic scientist Mohammad Ibn Zakariya al-Razi (864–930 CE), while others claim the first mention of the com-pound to have been by the Islamic writer Geber (probablyborn about 1270). In any case, European scientists apparentlydid not discover sulfuric acid on their own until the six-teenth century, when the Belgian scientist Johann Baptista

S

O

O

OH

HO


van Helmont (1579-1644) described its preparation by addingwater to the gas formed when sulfur was burned. The discov-ery of sulfuric acid proved to be an important development inthe early history of modern chemistry. For the first time, itgave chemists an acid far stronger than the vinegar withwhich they previously had to work in analyzing mixtures andmaking new chemical compounds.

HOW IT IS MADE

The first commercially successful method for makingsulfuric acid was developed in 1746 by English physician,chemist, and inventor John Roebuck (1718–1794). Roebuck’smethod is called the lead chamber process because the acid ismade in large containers lined with lead. The lead chamberprocess involves three primary steps: the combustion ofsulfur to produce sulfur dioxide; the conversion of sulfur

Sulfuric acid. Red atoms areoxygen; white atoms are

hydrogen; and yellow atom issulfur. Gray sticks indicatedouble bonds. P U B L I S H E R S



SULFURIC ACID

dioxide to sulfur trioxide; and the reaction of sulfur trioxidewith water to make sulfuric acid:

S + O2 ! SO2

2SO2 + O2 ! SO3

SO3 + H2O ! H2SO4

Although the process looks fairly simple, the reactionsare actually somewhat complex because of other compoundsneeded to make the reactions occur.

The second method for making sulfuric acid is known asthe contact process. It was invented about 1830 by an Englishvinegar merchant from Bristol, Peregrine Phillips. The che-mical reactions involved in Phillips’ process are identical tothose in the lead chamber process, but they are carried outover a catalyst of finely divided platinum metal. Phillipsfound that the yield obtained (the amount of raw materialconverted to useful product) was much higher than with thelead chamber process.

As it happens, little attention was paid to Phillips’ dis-covery because there was not much demand for sulfuric acidat the time. It was not until the invention of synthetic dyes afew decades later that the compound became commerciallyimportant. But even then, the lead chamber process was thepreferred method for making sulfuric acid. Over time,improvements were made in the contact process, and it gra-dually became more and more popular. Today, nearly all ofthe sulfuric acid produced is manufactured by some modifi-cation of Peregrine Phillips’ method.


The most important single use of sulfuric acid is for theproduction of phosphoric acid (H3PO4), which in turn is usedto make fertilizers. About 70 percent of all the sulfuric acidused in the United States goes to this application. Someother uses of sulfuric acid include:

• As the electrolyte in lead storage batteries (the liquidthrough which charged particles flow);

• For the processing of gasoline and other petrochem-icals, as a way of removing impurities present in theproducts;


SULFURIC ACID

• As a cleaning agent for metal surfaces, especially priorto their being plated with a second metal;

• In the manufacture of explosives, dyes, glues, pigments,rayon, and films;

• As a catalyst in a variety of industrial chemical andresearch chemical reactions; and

• In the processing of ores in preparation for the extrac-tion of metals.

Sulfuric acid is a highly corrosive material that causessevere damage to the skin, eyes, and respiratory system. Ifspilled on the skin or eyes, it can cause inflammation, burns,and blistering, and cause serious damage to one’s vision. If

Words to Know



Interesting Facts

• Sulfuric acid’s commonname is oil of vitriol. Thatname comes from the factthat it was once producedfrom either iron(II) sulfate,known as ‘‘green vitriol,’’ orfrom copper(II) sulfate,known as ‘‘blue vitriol.’’

• The conversion of sulfurdioxide to sulfur trioxide inthe manufacture of sulfuricacid does not occur veryreadily. That step controls

the efficiency with whichthe acid can be made. Phil-lips’ great breakthroughwas to find a catalyst thatmade that reaction takeplace more easily. Later,researchers found an evenmore efficient catalyst,vanadium pentoxide (V2O5).Today, vanadium pentoxideis still the most popularcatalyst in the productionof sulfuric acid.


SULFURIC ACID

swallowed, it causes severe burns of the gastrointestinaltract and irreversible damage to tissue and organs. Anyaccident in which sulfuric acid is inhaled, swallowed, orspilled on the body requires immediate medical attention.


‘‘Chemical of the Week: Sulfuric Acid.’’ Science is Fun.http://scifun.chem.wisc.edu/chemweek/Sulf&top/Sulf&Top.html (accessed on November 15, 2005).

‘‘Chronic Toxicity Summary: Sulfuric Acid.’’ Office of Environmental Health Hazard, State of California.http://www.oehha.org/air/chronic_rels/pdf/sulfuric.pdf(accessed on November 15, 2005).

‘‘Sulfuric Acid.’’ In World of Scientific Discovery. 2nd ed. Detroit:Gale Group, 1999.

‘‘Sulfuric Acid.’’ National Safety Council.http://www.nsc.org/library/chemical/sulfuric.htm (accessedon November 15, 2005).

‘‘Sulfuric Acid: Production and Uses.’’ Aus e tute.http://www.ausetute.com.au/sulfacid.html (accessed on November 15, 2005).

See Also Phosphoric Acid; Sulfur Dioxide


SULFURIC ACID

OTHER NAMES:Penta-(m-digalloyl)-

glucose; tannin;gallotannin

FORMULA:C76H52O46


oxygen


STATE:Solid


MELTING POINT:Begins to decompose

at 210�C (410�F)



ethyl alcohol, andacetone

Tannic Acid

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OVERVIEW

Tannic acid (TAN-ik AS-id) is a pale yellow amorphouspowder, shiny scales, or spongy material that gradually dar-kens when exposed to air. It is odorless but has a strong,bitter taste. It is a derivative of the simple sugar glucose(C6H12O6) in which five hydroxyl groups (-OH) have beenreplaced by large complex side chains known as digalloylgroups. Tannic acid occurs naturally in the bark of hemlock,chestnut, mangrove, and oak trees; in sumac plants; and in

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plant galls, the hard swellings that develop on trees infestedwith insect parasites. The name tannic acid comes from thefact that the compound is used in the process known astanning. It transforms the proteins in raw animal hides intoforms that resist the natural process of decomposition, con-verting the hides into leather. Tannic acid belongs to a largeclass of chemical compounds known as tannins that have thecommon chemical property of being able to precipitate pro-teins. Precipitation is the process by which the soluble formof a substance is converted to an insoluble form, which thensettles out of solution. In addition to its applications intanning, tannic acid is also used for staining wood, dyeingcloth, and treating minor cuts and wounds.

Tannic acid. Red atoms areoxygen; black atoms are carbon;and white atoms are hydrogen.



TANNIC ACID

HOW IT IS MADE

Tannic acid is extracted from natural source by using theprinciple that the compound is soluble in water and alcohol,while many components with which it occurs are not. Themost common sources of tannic acid have traditionally beenthe Chinese nutgall, which consists of about 70 percent tannicacid, and Turkish nutgall, which contains about 50 to 60percent tannic acid. The nutgall is ground into a powder andthen mixed with a combination of water and/or alcohol andether. The tannic acid in the powder dissolves in the water/alcohol portion of the mixture, and other components of thegall dissolve in the ether portion. The water and alcohol arethen allowed to evaporate, leaving behind relatively pure tan-nic acid. In recent years, tannic acid has been obtained moreeconomically from the bark of the quebracho tree, whichgrows in South America and is related to poison ivy.


Tannic acid continues to be used for many of the applica-tions for which it has been known for centuries, including

Interesting Facts

• A kind of ink called iron

gall ink is made fromtannic acid, iron(II) sulfate,gum arabic, and water. Therecipe for this ink hasbeen known since theMiddle Ages. It is used forimportant documentsbecause it does not wearaway easily.

• Tannic acid is mentionedin some very old medicalbooks as a treatment formushroom poisoning.

• Studies suggest thatpeople allergic to cats may

be able to control theirallergies by sprayingsurfaces in the home witha solution of tannic acid.The compound chemicallyalters the proteins infeline saliva that triggerallergic reactions.

• Tannic acid is not a trueacid because it does notcontain the carboxyl group(-COOH) present in allorganic acids. Instead, it isa polyphenol, a compoundwith many (‘‘poly’’) phenol(C6H5OH) groups.


TANNIC ACID

the tanning of animal hides, the manufacture of specializedinks, and the treatment of minor cuts and bruises. Its medi-cal applications are based on its astringent properties. Anastringent is a compound that triggers a loss of water fromtissue, thereby causing the tissues to shrink and contract.The compound also has a number of other commercial andindustrial uses, including:

• As a mordant in the coloring of fabrics and the printingof colored papers;

• In the manufacture of many kinds of chemicals, includ-ing tannates (compounds of tannic acid and a metal),gallic acid (C6H2(OH)3COOH; with many of the sameuses as tannic acid), and pyrogallic acid (C6H3(OH)3; alsowith similar uses);

• As a clarifying (purifying) agent in the manufacture ofbeers and wines;

• In electroplating;

• In the manufacture of artificial horn and tortoise shellproducts;

• As a coagulant in the manufacture of rubber to precipi-tate out impurities;

• In the deodorizing of crude oil; and

• In photographic processes.

Words to Know

AMORPHOUS Without crystalline structure.

ELECTROPLATING A process by which athin layer of one metal is deposited on topof a second metal by passing an electriccurrent through a solution of the firstmetal.

MORDANT A substance used in dyeing andprinting that reacts chemically with both adye and the material being dyed to

help hold the dye permanently to thematerial.

MUTAGEN A substance that causes amutation in plants or animals. Mutationsare changes in an organism’s geneticcomposition.



TANNIC ACID

Tannic acid is a mild irritant of the skin, eyes, andrespiratory tract. It is toxic by ingestion. In large doses, itmay cause liver damage. No evidence is available on itscarcinogenic or mutagenic effects in humans.


Eusman, Elmer. ‘‘The Ink Corrosion Website.’’http://www.knaw.nl/ecpa/ink/ (accessed on November 15, 2005).

‘‘Material Safety Data Sheet: Tannic Acid.’’ GFS Chemicals. https://gfschemicals.com/Search/MSDS/2415MSDS.PDF (accessed onNovember 15, 2005).

Meyer, John R. ‘‘By Gall y.’’http://www.cals.ncsu.edu/course/ent591k/gally.html(accessed on November 15, 2005).

‘‘Tannic Acid/Tannins.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/t0065.htm(accessed on November 15, 2005).


TANNIC ACID


FORMULA:C19H28O2


oxygen

COMPOUND TYPE:Steroid (organic)

STATE:Solid




melting point


soluble in ethylalcohol, chloroform,

vegetable oils, ether,and other organic

solvents

Testosterone

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OVERVIEW

Testosterone (tes-TOS-ter-own) is a white to creamy-whitecrystalline or powdery material that is odorless and tastelessand stable in air. It is a member of the organic family ofcompounds known as androgenic steroids—hormones respon-sible for the development of male sexual characteristics,such as male sex organs, a deep voice, and facial hair. Tes-tosterone is present in both male and female bodies,although to a greater extent in men than in women.

The earliest studies of testosterone were conducted byFrench physiologist Charles E. Brown-Sequard (1817–94),sometimes called the father of endocrinology. Endocrinologyis the study of hormones, their effects, and the glands thatproduce them. In 1889, at the age of 72, Brown-Sequardinjected himself with extracts from dog and pig testes andreported a major change in his physical and mental health.He reported that he had regained the strength that he hadas a younger man. He also said the extract improved hisintellectual abilities. Brown-Sequard’s scientific colleagues

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laughed off his discoveries, and studies of testosterone werelargely suspended for almost half a century.

In the 1930s, however, interest in the compound wasrevived. In 1935, scientists obtained the first pure samplefrom testosterone and were able to confirm Brown-Sequard’sfindings. Within a matter of years, the compound becameespecially popular among middle-aged men who believed thatit could restore their physical and mental abilities. Testoster-one was first synthesized in 1935 by German chemist AdolfFriedrich Johann Butenandt (1903–1995), an accomplishmentfor which he was awarded the 1939 Nobel Prize in Chemistry.

Testosterone is also known by the following names;17b-Hydroxyandrost-4-ene-3-one; androst-4-en-17b-ol-3-one;testosteroid; testosteron; testostosterone; and trans-testosterone.

HOW IT IS MADE

Testosterone is produced naturally in the male testes andthe female ovaries. It is also made synthetically startingeither with cholesterol or diosgenin, a plant steroid.

Testosterone. Red atoms areoxygen; white atoms

are hydrogen; and black atomsare carbon. Gray sticks indicate




TESTOSTERONE


Both males and females of all vertebrate species producetestosterone. The amount present in the male body is con-siderably greater than that present in the female body. Tes-tosterone has a number of biological effects on the body,including an increase in the number of red blood cells andmuscles cells and initiation of the development of male sexorgans. It is also responsible for the development of second-ary male sexual characteristics, such as the growth of bodyand facial hair, deepening of the voice, and increased sexualdesire. Some less desirable effects are an increase in oilinessof the skin and acne.

Testosterone production in men tends to increase duringchildhood and reaches a maximum during the late teens orearly twenties. It then decreases throughout the rest of aman’s life. A sudden or extreme decrease in testosteronelevels, caused by disease or injury to the hypothalamus,pituitary gland, or testes, can lead to a medical conditionknown as hypogonadism.

Treatments for hypogonadism in the form of testoster-one injections, tablets, skin patches, and skin gels are avail-able. Some men use these devices in an attempt to revivemasculine traits that begin to decline normally as one growsolder. Many individuals believe, like Brown-Sequard, thattestosterone can be something of a ‘‘miracle drug’’ that willrestore their lost youth. It has at times been recommendedalso as a treatment for a host of medical problems, includinginfertility, impotence, lack of sex drive, osteoporosis,

Interesting Facts

• Women who choose toundergo a series ofprocedures to change theirgender are requiredto take testosterone overa period of manymonths to stimulate

the development ofmale sex characteristics.They must continuetaking testosteronesupplements for the restof their lives.


TESTOSTERONE

shortness of stature, anemia, and low appetite. Testosteronemay or may not be helpful in treating any one of theseconditions.

Since the 1950s, athletes have been using testosterone,its derivatives, and related compounds to improve their per-formance. The compound increases a person’s bone and mus-cle mass, significantly improving his or her strength andendurance. Testosterone was first used on a large scale basisby athletes from the Soviet Union in the 1950s as part ofthat nation’s efforts to become dominant in world sports.

One problem with using testosterone as a performance-enhancing drug is its undesirable side effects. It tends toincrease the size of a man’s prostate gland and decrease thesize of his testicles. It may also produce wide mood swingsthat may include dangerously aggressive feelings.

Because of these side effects, researchers have developedcompounds that produce the same effects as those obtainedfrom natural testosterone, but without the compound’s harm-ful side effects. Some of those compounds increase the naturalproduction of testosterone in the body when they are ingested.Others are derivatives of testosterone, compounds with simi-lar chemical structures, but minor changes that reduce sideeffects. These derivatives include compounds such as dihydro-testosterone, androstenedione (also known as andro), dehy-droepiandrosterone (DHEA), clostebol, and nandrolone. Todaymost derivatives of testosterone and testosterone-producingcompounds are banned by sports organizations, both becauseof their harmful side effects and because of the unfair advan-tages they provide athletes who use them.

Words to Know

ANDROGENIC STEROID A hormoneresponsible for the development of malesexual characteristics.

DERIVATIVE A chemical whose structureis based on or related to anotherchemical.

HORMONE A chemical produced by livingcells in a body that promotes the activityof other cells in the body.



TESTOSTERONE


Hellstrom, Wayne J. G. ‘‘Testosterone Replacement Therapy.’’Digital Urology Journal.

http://www.duj.com/Article/Hellstrom2/Hellstrom2.html(accessed on November 15, 2005).

‘‘Material Safety Data Sheet: Testosterone.’’ Paddock Laboratories,Inc.http://www.paddocklabs.com/forms/msds/testost.pdf(accessed on November 15, 2005).

‘‘Testosterone.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/pims/pharm/pim519.htm(accessed on November 15, 2005).

‘‘Testosterone Deficiency.’’ Urology Channel.http://www.urologychannel.com/testosteronedeficiency/index.shtml (accessed on November 15, 2005).


TESTOSTERONE

OTHER NAMES:3,7-Dimethylxanthine;

3,7-dihydro-3,7-dimethyl-1H-purine-

2,6-dione

FORMULA:C7H8N4O2


nitrogen, oxygen

COMPOUND TYPE:Alkaloid (organic

base)

STATE:Solid


MELTING POINT:Begins to sublime atabout 290�C (554�F)



water and ethylalcohol; virtually

insoluble in benzene,chloroform, ether,and other organic

solvents

Theobromine

KE

YF

AC

TS

OVERVIEW

Theobromine (thee-oh-BROH-meen) is a white crystallinesolid that occurs naturally in cocoa beans, from which chocolateis obtained, and, in smaller amounts, in tea and cola nuts. Theo-bromine is structurally very similar to caffeine, which differsonly in the presence of a methyl group (-CH3) on one of thenitrogen atoms in the theobromine molecule. Both theobromineand caffeine belong to a family of organic compounds known asthe methylxanthines. Theobromine’s effects on the human bodyare similar to those of caffeine, but about ten times weaker. Inaddition, caffeine is metabolized more quickly, is addictive, andincreases alertness and emotional stress. It may also have ser-ious effects on the central nervous system and the kidneys. Bycontrast, theobromine produces feelings of well-being, is notaddictive, has no effect on the central nervous system, andprovides only gentle stimulation to the kidneys. Its effects onthe body are much longer-lasting than are those of caffeine.

The amount of theobromine in cocoa beans varies widely,ranging from 10 to 40 milligrams of theobromine per gram

NC

O

C

CN

N

NC

C H

H

O

CH3

CH3


of cocoa. The variation depends on a number of facts, includ-ing the type of bean, the location where it was grown, andthe method of processing the bean. All chocolate productscontain theobromine, but the amount varies depending onthe type of chocolate. Dark chocolate contains significantlymore of the compound than milk chocolate, and high qualitychocolate tends to contain more theobromine than low qual-ity chocolate. The characteristic bitter taste of dark choco-late is due to the theobromine present in it.

HOW IT IS MADE

Theobromine is usually obtained from the hulls of cocoabeans left over after the production of chocolate. The hulls

Theobromine. Red atoms areoxygen; white atoms


are nitrogen. Gray sticksindicate double bonds.



THEOBROMINE

are crushed and then treated with an absorbent, such aswater or liquid carbon dioxide, which dissolves the theobro-mine. The water or carbon dioxide is then allowed to evapo-rate, permitting the crystallization of the pure compound.


Theobromine occurs in all chocolate products. The purecompound has relatively few uses, however, most of themmedical. For example, it has been used as a diuretic—a com-pound that increases the rate at which liquids are eliminatedfrom the body—and as a mild stimulant. It has also been usedto treat hypertension (high blood pressure) because it is avasodilator, a compound that causes blood vessels to relax

Interesting Facts

• The name theobromine isderived from the scientificname for the cacao tree,Theobroma cacao.

• Spanish armies thatinvaded South and CentralAmerica in the sixteenth

century used chocolate asa source of energy.

• Theobromine is harmlessto humans, but very toxicto dogs, horses, and otherdomestic animals.

Words to Know

DIURETIC A compound that increases therate at which liquids are eliminated fromthe body.

METHYLXANTHINE A compound that isderived from xanthine (C5H4N4O2), withmethyl groups (CH3) replacing one or moreof the hydrogen atoms.

STIMULANT: A substance that increases theactivity of a living organism or one of itsparts.

SUBLIME To go from solid to gaseous formwithout passing through a liquid phase.


THEOBROMINE

and expand in size. Theobromine also appears to be effectiveas a cough suppressant, although the quantities needed toachieve useful effects are quite large.


O’Neil, John. ‘‘And It Doesn’t Taste Bad, Either.’’ New York Times

(November 30, 2004): F9.

‘‘[email protected].’’ Molecule of the Month.http://www.3dchem.com/molecules.asp?ID=155 (accessed onNovember 15, 2005).

‘‘What Is Theobromine and What Is Its Effect on Human Beings?’’International Cocoa Organization.http://www.icco.org/questions/theobromine.htm (accessed onJanuary 11, 2006).

See Also Caffeine; Carbon Dioxide


THEOBROMINE

OTHER NAMES:Vitamin B1

FORMULA:C12H17ClN4OS


chlorine, nitrogen,oxygen, sulfur


STATE:Solid





partially soluble inethyl alcohol

Thiamine

KE

YF

AC

TS

OVERVIEW

Thiamine (THYE-uh-min) is the water-soluble vitamin, vita-min B1. It is also known as 3-(4-Amino-2-methylpyrimidyl-5-methyl)-4-methyl-5,b-hydroxyethylthiazolium. It is usuallymade available as one of its salts, especially thiamine hydro-chloride or thiamine mononitrate. Both salts are white crystal-line solids with a bitter taste that are destroyed by alkalinesolutions. An alkaline solution is one that contains a strongbase.

Thiamine was discovered by Japanese scientist SuzukiUmetaro (1874–1943) in the early twentieth century. Umetarowas investigating a disease known as beriberi that had pla-gued humans for thousands of years. He found that the dis-ease could be cured by feeding patients a diet that containedrice bran. He was also able to isolate a specific compound inrice bran that produced that effect, a compound he namedaberic acid. Aberic acid later became known as thiamine.

The first written reports of beriberi date back 4,000 years.Chinese scholars described a disorder characterized by nausea,

C C

Cl–H

H

H

H

H

HH

NH2

N HHC C

N+

C

H3C

NC

CC O

C

SC

CH3


vomiting, constipation, abdominal pain, weakness, wasting,paralysis, irritability, paranoia, depression, and other mentalsymptoms. In the 1800s, most scientists were convinced thatbacteria were responsible for the disease. Over time, it becameapparent that this theory was incorrect and that dietary factors

Thiamine. Red atom is oxygen; whiteatoms are hydrogen; black atoms arecarbon; blue atoms are nitrogen; and

yellow atom is sulfur. Gray sticksindicate double bonds. P U B L I S H E R S



were responsible for beriberi. In the late nineteenth century,for example, Japanese naval scientist Kanehiro Takaki (1849–1920) noticed that sailors on long voyages developed beriberiif their diets consisted mainly of rice with hulls removed. Healso observed that the sailors remained healthy if theyincluded fish, vegetables, wheat, and milk along with rice intheir diets.

In 1896, Dutch physician Christiaan Eijkman (1858–1930) found that animals developed beriberi only if theyate polished rice—rice from which hulls had been removed.He learned that the animals recovered if they ate rice withhulls still on it. His colleague Gerrit Grijins (1865–1944)believed that the rice hulls contained some substance thatprevented beriberi. By 1910, Umetaro had found that sub-stance, aberic acid.

HOW IT IS MADE

Humans are unable to synthesize thiamine, so they mustobtain the vitamin from other sources in which it occursnaturally. The best sources of thiamine are brewer’s yeast,whole grains, wheat germ, lean meats, organ meats (such asliver and kidney), fish, dried beans, soybeans, peas, nuts,green leafy vegetables, avocados, raisins, plums, and kelp.Thiamine is also made synthetically by a process that wasfirst developed in the 1930s by American chemist Robert R.

Interesting Facts

• The word beriberi comesfrom the Sinhaleseexpression ‘‘I can’t, I can’t.’’Sinhalese is the languagespoken by natives ofSri Lanka.

• As of 2006, Beriberi is rarein developed countriesbecause of the readyavailability of foods and

vitamin supplements thatcontain vitamin B1.The disease becamecommon in Cuba between1989 and 1995, however.A trade embargo imposedby the United Statesreduced the availability offoods and vitamins for theCuban people.


THIAMINE

Williams (1886–1965). Williams began his studies of anti-beriberi compounds in 1911 and worked for twenty-five yearsbefore discovering the correct chemical formula for the com-pound. Once he had that information, he was able to invent asystem for producing the vitamin artificially. Today, vir-tually all of the vitamin B1 sold commercially is preparedartificially.


Thiamine is a coenzyme needed for a number of essentialbiochemical reactions in the body. A coenzyme is a chemicalcompound that works along with an enzyme to increase therate at which chemical reactions take place. Withoutenzymes and coenzymes in the body, many chemical reac-tions would take place so slowly that normal bodily functionscould not continue. Thiamine is involved in chemical reac-tions by which blood is produced and circulated through thebody, carbohydrates are metabolized, digestive enzymes areproduced, and the nervous system is maintained.

Because it is soluble in water, thiamine is not stored inthe body. A person must include the compound in his or herdaily diet on a regular basis. Most people ingest adequateamounts of vitamin B1 in their ordinary diets, and beriberi isvery rare in developed countries of the world. It may occur,however, in alcoholics, pregnant women, and people whomust undergo kidney dialysis. In all of these cases, a persondoes not receive adequate amounts of the vitamin for thebody’s needs. In the case of alcoholics, for example, alcoholreplaces the calories they would be getting from food if theywere not drinking so much. As a result, they do not getenough vitamin B1 and other nutrients needed to stayhealthy.

Words to Know

COENZYME A chemical compound that worksalong with an enzyme to increase the rateat which chemical reactions take place.

SALT An ionic compound where the anionis derived from an acid.


THIAMINE

The early symptoms of beriberi include fatigue, irritabil-ity, poor sleep habits, memory loss, abdominal pain, loss ofappetite, and constipation. As the disease progresses, it mayproduce damage to the peripheral nervous system that servesthe arms, legs, feet, and hands, resulting in muscular atrophy(weakness and wasting of the muscles) and loss of sensationin the toes.


Eades, Mary Dan. The Doctor’s Complete Guide to Vitamins and


‘‘Thiamine.’’ Medline Plus.http://www.nlm.nih.gov/medlineplus/ency/article/002401.htm (accessed on November 15, 2005).

‘‘Thiamine and Salts.’’ International Programme on ChemicalSafety.http://www.inchem.org/documents/pims/pharm/pimg015.htm(accessed on November 15, 2005).

‘‘Vitamin B1.’’ Welcome to Glactone.http://chemistry.gsu.edu/glactone/vitamins/b1/ (accessed onNovember 15, 2005).

See Also Ascorbic Acid; Cyanocobalamin; Pyridoxine;Riboflavin


THIAMINE

OTHER NAMES:Methylbenzene;phenylmethane;

toluol

FORMULA:C6H5CH3


COMPOUND TYPE:Aromatic hydrocar-

bon (organic)

STATE:Liquid





miscible with ethylalcohol, ether,

acetone, and carbondisulfide

Toluene

KE

YF

AC

TS

OVERVIEW

Toluene (TOL-yew-een) is a clear, colorless liquid with abenzene-like odor. It is an aromatic hydrocarbon, that is, a

compound that contains carbon and hydrogen only, with thecarbon atoms arranged in a ring. Aromatic compounds have

structures based on that of benzene (C6H6). Toluene wasdiscovered in 1838 by French chemist Pierre JosephPelletier (1788–1842). Pelletier found the compound in the

gas emitted by the bark of the pine tree Pinus maritima.

Pelletier named the substance retinnaphte, after pine resin.

The compound was re-discovered a number of times in lateryears and given a variety of names, including heptacarbure

quadihydrique, benzoene, and dracyl. Toluene’s chemicalnature was finally determined by German chemist August

Wilhelm von Hofmann (1818–1892) and British chemistJames Muspratt (1793–1886) who adopted the name toluol

originally proposed by Swedish chemist Jons Jakob Berzelius

(1779–1848).

C CH

C C

C C

HH

HH

C

H

H

H


HOW IT IS MADE

Toluene occurs naturally in petroleum and is extractedduring the catalytic reforming of the naphtha segment ofpetroleum. Catalytic reforming is a process by which hydro-carbons in petroleum are heated, often in contact with acatalyst, in order to change their molecular composition.The naptha segment of petroleum consists of a complexmixture of hydrocarbons with boiling points between about50�C and 200�C (120�F and 400�F). Toluene is separated fromother hydrocarbons produced during the reforming processby adding a solvent, such as sulfolane (c-CH2CH2CH2CH2SO2;the ‘‘c’’ at the beginning means that this is a ring compound)or tetraethylene glycol (HO(CH2CH2O)3CH2CH2OH). Thetoluene dissolves in one or the other of these solvents, whilemost other hydrocarbons with which it is mixed do not.Toluene is also obtained by a similar process starting with

Toluene. Black atoms arecarbon; white atoms are

hydrogen. Bonds in the benzenering are represented by thedouble striped sticks. White

sticks show single bonds.P U B L I S H E R S R E S O U R C E G R O U P


TOLUENE

coal tar oil, the liquid that remains when soft coal is heatedin the absence of air to make coke.


Toluene generally ranks among the top thirty compoundsproduced in the United States annually. In 2002, Americanchemical plants produced 330 million liters (87 million gal-lons) of toluene for domestic use and export. About half thatamount was used in the production of benzene and about20 percent for the production of xylene (C6H4(CH3)2).Another 18 percent went to the manufacture of other organicchemicals, one of the most important of which is toluenediisocyanate (CH3C6H3(NCO)2) used primarily for the produc-tion of polyurethane foams and artificial rubber products.The other major use for toluene is as a solvent for paints andother coatings, gums, oils, natural and artificial rubber pro-ducts, adhesives, and plastics. Some toluene is also used as ablending agent in aviation fuels and other gasoline mixtureswith high-octane ratings.

One application of toluene that consumes relatively smallamounts of the compound but that is very important is in theproduction of the explosive trinitrotoluene (TNT). TNT is avery desirable explosive because it detonates (explodes) onlywhen shocked or heated to temperatures above 230�C(450�F), but then releases very large amounts of energy.For many decades, TNT was one of the world’s most widely

Interesting Facts

• The name toluol (andtoluene) originally comesfrom an aromaticsubstance obtained fromthe bark of the SouthAmerican tree Myroxylon

balsamum.

• Toluene was firstsynthesized artificially

by German chemistsRudolf Fittig (1835–1910)and B. C. G. Tollens(1841–1918).

• Toluene is therecommended solventfor the removal of stainsmade by airplane cement.


TOLUENE

used explosives. Even today, the power of other explosives ismeasured by comparison with TNT. For example, the powerof nuclear weapons is said to be 10 kilotons or 10 megatons,meaning that they have an explosive power comparable to10,000 tons or 10 million tons, respectively, of TNT.

Toluene is a very hazardous chemical compound. Itcatches fire easily and, under proper conditions, is explo-sive. It is also an irritant to the skin, eyes, and respiratorytract. It may produce symptoms such as headache, dizziness,drowsiness, confusion, fatigue, and peculiar sensations ofthe skin, such as a ‘‘pins and needles’’ effect. It large quan-tities, toluene may cause unconsciousness, coma, and death.In contact with the skin or eyes, it may produce redness andpain. Prolonged exposure to toluene may cause seriousdamage to the liver and kidneys resulting in anemia,decreased blood cell count, and bone marrow hypoplasia(diminished ability to produce blood cells). Toluene isthought to be teratogenic, capable of damaging a fetuswhile still in the womb.


Harte, John, et al. Toxics A to Z. Berkeley: University of CaliforniaPress, 1991, 415 417.

Martin, Kevin A. ‘‘Toxicity, Toluene.’’ eMedicine.http://www.emedicine.com/emerg/topic594.htm (accessed onDecember 29, 2005).

Words to Know

AROMATIC COMPOUND A compound whosechemical structure is based on that ofbenzene (C6H6).

CATALYTIC REFORMING A process by whichhydrocarbons in petroleum are heated,often in contact with a catalyst, in order tochange their molecular composition.

MISCIBLE Able to be mixed; especiallyapplies to the mixing of one liquidwith another.


TERATOGENIC Capable of causing anorganism to develop incorrectly.


TOLUENE

‘‘Toluene.’’ International Chemical Safety Cards.http://www.cdc.gov/niosh/ipcsneng/neng0078.html (accessedon December 29, 2005).

‘‘Toluene.’’ J. T. Baker.http://www.jtbaker.com/msds/englishhtml/t3913.htm(accessed on December 29, 2005).

‘‘ToxFAQsTM for Toluene.’’ Agency for Toxic Substances and Disease Registry.http://www.atsdr.cdc.gov/tfacts56.html (accessed on December29, 2005).

See Also Benzene


TOLUENE

OTHER NAMES:3,4,4’-Trichloro-

carbanilide,N-(4-chlorophenyl)-

N’-(3,4-dichloro-phenyl)urea

FORMULA:C6H3Cl2NH-

CONHC6H4Cl

ELEMENTS:Carbon, hydrogen,nitrogen, oxygen,

chlorine


STATE:Solid




SOLUBILITY:Insoluble in water;soluble in fats and

many organicsolvents

Triclocarban

KE

YF

AC

TS

OVERVIEW

Triclocarban (TRY-klo-kar-ban) is a fine white powderwith a slight odor. It is used almost exclusively as an anti-microbial agent—a substance that kills microorganisms suchas bacteria and fungi. Triclocarban is available under a num-ber of trade names, including Cusiter�, Cutisan�, Genoface�,Procutene�, Solubacter�, and TCC�. The compound is aningredient in deodorant soaps, disinfectants, toothpastes,and other household products. It is also used in hospitals tocleanse and disinfect the skin of patients and medical staff.It remains on surfaces for relatively long periods of time,lengthening the disinfecting action, rather than breakingdown fairly quickly like many other disinfectants. Triclocar-ban can be imbedded in plastics and textiles to createlong-lasting antimicrobial surfaces, such as in toys and kitch-enware. It is sometimes used in combination with triclosan, asimilar antimicrobial agent.

Triclocarban works as a disinfectant because it disablesan enzyme called enoyl-acyl-carrier-protein reductase, or

C

H

H

H

H

H

H

H

H

H

NC

CC

C

C C

O

NC

C

C C

Cl

Cl

Cl

CC


ENR, that many bacteria and fungi use to make cellmembranes. If they cannot make cell membranes, thesemicroorganisms die. Humans do not have this enzyme, sotriclocarban is considered harmless to them. The use of tri-clocarban became more widespread after another popularantimicrobial, hexachlorophene, was banned by the U.S. Foodand Drug Administration in the 1970s. Hexachlorophene usewas discontinued after the antimicrobial was implicated inthe death of infants who had been exposed to the product. Inthe first years of the twenty-first century, triclocarban andtriclosan began to be used less, due to increased concernsabout the long-term effects of these compounds on thehuman body and on the environment.

HOW IT IS MADE

Triclocarban is synthesized by one of two procedures. Inone, 4-chlorophenyl isocyanate (ClC6H4NCO) is reacted with3,4-dichloroaniline (C6H3NH2Cl2) to give triclocarban. Therelationship of these two compounds to the structure ofthe final product (C6H3Cl2NHCONHC6H4Cl) is obvious fromtheir chemical structures. In the second method of prepara-tion 3,4-dichlorophenyl isocyanate (Cl2C6H3NCO) is reactedwith 4-chloroaniline (ClC6H4NH2) to give the desiredproduct.

Triclocarban. Red atomsare oxygen; white atoms

are hydrogen; black atoms arecarbon; green atoms arechlorine; and blue atomsare nitrogen. Gray sticks

indicate double bonds; stripedsticks indicate benzene rings.



TRICLOCARBAN


About three-fourths of all liquid soaps and nearly one-third ofall bar soap made in the United States contains antimicrobialagents such as triclocarban and triclosan. Research has shown,however, that washing one’s hand with plain soap and waterprovides as much protection from disease-causing organisms asdo antimicrobial soaps. It is apparently the action of washing thatremoves most bacteria. Many public health experts say that anti-microbial soaps are not necessary in normal healthy households.

The growing concern is that the widespread use of anti-microbial soaps may cause harmful bacteria and fungi tobecome resistant to antimicrobial agents such as triclocarbanand triclosan. That could happen if the genes in microorgan-isms that produce the enzyme ENR mutate, that is, changetheir chemical structure. Bacteria carrying the new genemight be more resistant to antimicrobial compounds.

Triclocarban has been shown to cause contact dermatitis,an allergic skin rash caused by contact with an irritatingsubstance. This effect is of particular concern among infantsand small children. The compound has been implicated inillnesses among newborns, and its use in maternity wards isdiscouraged. However, the compound is effective in treatingother forms of skin rashes, such as atopic dermatitis, alsoknown as eczema, because it kills the bacteria that cause thecondition. Although the effects of ingesting triclocarbanhave not been thoroughly investigated, there is some ques-tion about the compound’s possible carcinogenic effects.

Interesting Facts

• Hunters sometimes washtheir clothes in detergentsthat contain triclocarbanto kill the bacteria thatcontribute to body odor. Inthis way, the animals onwhom they prey, such asdeer, are less likely to

detect the smell of thehunter and flee the scene.

• No triclocarban is manu-factured in the UnitedStates. It is imported fromother countries, primarilyChina and India.


TRICLOCARBAN

Triclocarban is considered by some authorities to be anenvironmental hazard, as well as a risk to human health. Thecompound is released into waterways when it is used forwashing and bathing. Although wastewater treatment plantscan remove up to 98 percent of the triclocarban in water,public health researchers have found the compound in60 percent of the U.S. waterways studied. In one study, itwas the fifth most common contaminant among 96 pollu-tants studied. The half life of triclocarban (the time it takesfor half of the substance to disappear) is 1.5 years. Thatmeans that the compound will remain in water supplies forrelatively long periods of time, certainly more than a fewyears. Although triclocarban is harmless to humans, it can betoxic to some types of aquatic life such as shellfish.


‘‘3,4,4’ Trichlorocarbanilide.’’ Hazardous Substances Data Bank.http://toxnet.nlm.nih.gov/cgi bin/sis/search (accessed on November 19, 2005).

‘‘Anti bacterial Additive Triclocarban Widespread in U.S. Waterways.’’ Johns Hopkins Bloomberg School of Public Health,Public Health News Center.http://www.jhsph.edu/PublicHealthNews/Press_Releases/2005/Halden_triclocarban_triclosan.html (posted on January21, 2005; accessed January 6, 2006).

Senese, Fred. ‘‘What Are Triclocarban and Triclosan (Ingredientsin Some Antiseptic Soaps)?’’ General Chemistry Online!http://antoine.frostburg.edu/chem/senese/101/consumer/faq/triclosan.shtml (accessed on November 19, 2005).

See Also Triclosan

Words to Know

ANTIMICROBIAL A substance that destroysmicroorganisms such as bacteria and fungi.


ENZYME A complex protein that isproduced by living cells and whichpromotes biochemical reactions inthe body.


TRICLOCARBAN


FORMULA:C6H3ClOH-O-C6H3Cl2


oxygen, chlorine


STATE:Solid


MELTING POINT:55�C to 57�C (131�F to

135�F)



water; soluble inmany organic

solvents

Triclosan

KE

YF

AC

TS

OVERVIEW

Triclosan (TRY-klo-san) is a white crystalline powder withantimicrobial properties that make it a useful ingredient in soaps,cosmetics, acne medications, deodorants, foot sprays and footpowders, toothpastes, and mouthwashes. It acts as an antimicro-bial by inhibiting the action of an enzyme called enoyl-acyl carrier-protein reductase (ENR) that bacteria and fungi need to survive.The enzyme is used in the synthesis of fatty acids from which cellmembranes are constructed. Having lost the ability to manufac-ture cell walls, bacteria and fungi die. The ENR enzyme is notpresent in humans, so triclosan has no effect on the human body.

Triclosan is also known by the following names: 5-chloro-2-(2,4-dichlorophenoxy)phenol; trichloro-2’-hydroxydiphenyl-ether; and 2,4,4’-trichloro-2’-hydroxydiphenyl ether.

HOW IT IS MADE

Two procedures are available for the synthesis of triclo-san. In one, 1,4-dichloro-2-nitrobenzene (C6H3Cl2NO3) is

H

HH

Cl

C C

C C

C OC

HOClH

HH

Cl

C C

C C

CC


reacted with 2,4-dichlorophenol (C6H3ClOH) to obtain triclo-san. In the second procedure, 2,4-dichlorobenzene (C6H4Cl2),acetyl chloride (CH3OCl), and 2,4-dichlorophenol (C6H3ClOH)are reacted with each other to obtain the product.


Triclosan has been used in soaps and other cleaningproducts since the 1960s. Hospitals found the compoundto be very effective in controlling bacteria on hands andsurfaces. Medical staff used it to stop outbreaks of infec-tions caused by common bacteria such as Staphylococcus

aureus. The compound is still used widely in hospitals forthis purpose. In the 1990s, triclosan began to appear in amuch wider array of products including antibacterial soaps,body washes, toothpastes, and dishwashing liquids. By theearly 2000s, it was also being used in toothbrushes, plastictoys, and socks. The addition of triclosan to tooth careproducts is based on evidence that the compound may inhi-bit the growth of bacteria that cause dental caries (cavities).The compound has also proved to be effective in killing the

Triclosan. Red atomsare oxygen; white atoms

are hydrogen; black atoms arecarbon; and green atoms are

chlorine. Dark gray sticksare double bonds; other sticksare single bonds. P U B L I S H E R S



TRICLOSAN

parasites that cause malaria, one of the most serious dis-eases in the world.

In spite of its wide use, a number of questions have beenraised about the inclusion of triclosan in household andcommercial products. One objection is based on the concernthat widespread use of the compound may lead to the devel-opment of bacteria resistant to antibiotics. Questions havealso been raised about byproducts of the reactions by whichtriclosan is produced and by which it is degraded in the soil.Among those byproducts are a family of organic compoundsknown as the dioxins, among the most potent toxins knownto humans. In addition, studies suggest that cleaning pro-ducts that contain triclosan are not any more effective inkilling germs than is the ordinary procedure of washingone’s hands with soap and water. As a result, the FederalTrade Commission has ordered some companies to stop claim-ing that their product kills germs and reduces disease. TheU.S. Environmental Protection Agency has listed triclosan asa possible human carcinogen.

Interesting Facts

• Soaking socks in asolution that containstriclosan can preventfood odor because thecompound kills the

bacteria that grow on feetand are responsible for theodor.

Words to Know


SYNTHESIS A chemical reaction inwhich some desired product is made

from simple beginning chemicals,or reactants.


TRICLOSAN


Glaser, Aviva. ‘‘The Ubiquitous Triclosan.’’ Beyond Pesticides.http://www.beyondpesticides.org/pesticides/factsheets/Triclosan%20cited.pdf (accessed on November 19, 2005).

‘‘Material Safety Data Sheet.’’ Jeen International Corporation.http://www.jeen.com/cartexe/pdfs/msds%20JEECHEM%20TRICLOSAN.pdf (accessed on November 19, 2005).

Mirsky, Steve. ‘‘Home, Bacteria Ridden Home: Could AntibacterialSoaps Lead to Resistant Strains?’’ Scientific American (July 19,1997). Also available online athttp://sciam.com/article.cfm?articleID=0009078D A418 1C769B81809EC588EF21 (accessed on November 19, 2005).

See Also Triclocarban


TRICLOSAN

OTHER NAMES:Carbamide;

carbonyldiamide

FORMULA:(NH2)2CO

ELEMENTS:Carbon, nitrogen,

hydrogen, oxygen


STATE:Solid




decomposes above itsmelting point


ethyl alcohol, andbenzene; slightly

soluble in ether

Urea

KE

YF

AC

TS

OVERVIEW

Urea (yoo-REE-uh) is a white crystalline solid or powderwith almost no odor and a salty taste. It is a product of thedecomposition of proteins in the bodies of terrestrial ani-mals. Urea is produced in the liver and transferred to thekidneys, from which it is excreted in urine. The compoundwas first identified as a component of urine by French che-mist Hilaire Marin Rouelle (1718–1799) in 1773. It was firstsynthesized accidentally in 1828 by German chemist FriedrichWohler (1800–1882). The synthesis of urea was one of themost important historical events in the history of chemistry.It was the first time that a scientist had synthesized anorganic compound. Prior to Wohler’s discovery, scientistsbelieved that organic compounds could be made only by theintervention of some supernatural force. Wohler’s discoveryshowed that organic compounds were subject to the same setof natural laws as were inorganic compounds (compoundsfor non-living substances). For this reason, Wohler is oftencalled the Father of Organic Chemistry.

C

O

N N

H

H

H

H


HOW IT IS MADE

The formation of urea is the evolutionary solution to theproblem of what to do with poisonous nitrogen compoundsthat formed when proteins decompose in the body. Proteinsare large, complex compounds that contain relatively largeamounts of nitrogen. When they decompose, that nitrogen isconverted to ammonia (NH3), a substance that is toxic toanimals. If animals are to survive the decomposition of pro-teins (as happens whenever foods are metabolized), somemethod must be found to avoid the buildup of ammonia inthe body.

That method involves a series of seven chemical reac-tions called the urea cycle by which nitrogen from proteins

Urea. Red atom is oxygen;white atoms are hydrogen;

black atom is carbon; and blueatoms are nitrogen. Gray sticks



UREA

is converted into urea. Although high concentrations of urea

do pose a risk to animal bodies, the urea formed in thesereactions is normally excreted fast enough to avoid health

problems for an animal.

Urea is produced commercially by the direct synthesis

of liquid ammonia (NH3) and liquid carbon dioxide (CO2).The product of this reaction is ammonium carbamate(NH4CO2NH2):

2NH3 + CO2 ! NH4CO2NH2

Ammonia and carbon dioxide do not react with eachother under normal conditions of temperature and pressure.

If the pressure is raised to 100 to 200 atmospheres (1750 to3000 pounds per square inch) and the temperature is raised

to about 200�C (400�C), however, the reaction proceeds effi-ciently with the formation of ammonium carbamate. When

the pressure is then reduced to about 5 atmosphere (80pounds per square inch), the ammonium carbamate decom-

poses to form urea and water:

NH4CO2NH2 ! (NH2)2CO + H2O

Interesting Facts

• Different species of ani-mals have evolved differentmethods of eliminatingammonia from their bodies.For example, fish excretethe ammonia produced bythe decomposition ofproteins directly into thewatery environment inwhich they live. Birds, whoconsume less water bygram of weight than domost other animals,convert ammonia to

uric acid (C5H4N4O3), awhite crystalline solid thatis even less toxic thanurea.

• Urea is transported fromthe liver to the kidneys inthe bloodstream. By thetime it leaves the body inurine, its concentrationis sixty to seventy timesits concentration in thebloodstream.


UREA


Urea is the sixteenth most important chemical in theUnited States, based on the amount produced annually. In2004, the chemical industry produced 5.755 million metrictons (6.344 million short tons) of urea. Almost 90 percent ofthat output was used in the manufacture of fertilizers. Anadditional 5 percent went to the production of animal feeds.In both fertilizers and animal feeds, urea and the compoundsfrom which it is made provide the nitrogen needed by grow-ing plants and animals for their good health and survival.The other major use of urea is in the manufacture of varioustypes of plastics, especially urea-formaldehyde resins andmelamine.

Urea is also used:

• In the production of personal care products, such ashair conditioners, body lotions, and dental products;

• In certain pharmaceutical and medical products, such ascreams to treat wounds and damaged skin;

• As a stabilizer in explosives, a compound that placeslimits on the rate at which an explosion proceeds;

• In the manufacture of adhesives;

• For the flame-proofing of fabrics;

• For the separation of products produced during therefining of petroleum;

• In the production of sulfamic acid (HOSO2NH2), animportant raw material in many chemical processes;

• As a coating for paper products; and

• In the production of deicing agents.

Words to Know

METABOLISM All of the chemical reactionsthat occur in cells by which fats, carbohy-drates, and other compounds are brokendown to produce energy and the compoundsneeded to build new cells and tissues.



UREA


National Urea Cycle Disorders Foundation.http://www.nucdf.org/ (accessed on November 19, 2005).

Ophardt, Charles E. ‘‘Urea Cycle.’’ Virtual Chembook.http://www.elmhurst.edu/~chm/vchembook/633ureacycle.html (accessed on November 19, 2005).

‘‘Urea.’’ International Programme on Chemical Safety.http://www.inchem.org/documents/icsc/icsc/eics0595.htm(accessed on November 19, 2005).

‘‘Urea.’’ Third Millennium Online.http://www.3rd1000.com/urea/urea.htm (accessed on November19, 2005).

See Also Ammonia


UREA

OTHER NAMES:4-hydroxy-3-methoxy-

benzaldehyde;3-methoxy-4-hydroxy-

benzaldehyde; vanillicaldehyde

FORMULA:(CH3O)(OH)C6H3CHO


oxygen

COMPOUND TYPE:Ether (organic)

STATE:Solid





water; soluble inglycerol, ethyl

alcohol, ether, andacetone

Vanillin

KE

YF

AC

TS

OVERVIEW

Vanillin is a white crystalline solid with a pleasant, sweetaroma, and a characteristic vanilla-like flavor. Chemically, itis the methyl ether of 4-hydroxybenzoic acid, a ring com-pound that contains the carboxyl (-COOH) group and thehydroxyl (-OH) group. Vanillin is the substance responsiblefor the familiar taste of vanilla, which has been used as afood additive and spice for hundreds of years. Vanilla wasprobably first used as a flavoring by the inhabitants of Southand Central America before the arrival of Europeans in thesixteenth century. Spanish explorers brought the spice backto Europe, where it soon became very popular as a foodadditive and for the flavoring of foods. Since that time,vanilla has become one of the world’s most popular spices.

HOW IT IS MADE

Vanilla is obtained naturally from the seed pod of thetropical orchid Vanilla planifolia by a lengthy and expensive

C

H

C

O

C CC H

CC H

O

H

H

OCH3


process. The pods are picked before they ripen and thencured until they are dark brown. The curing process involvessoaking the pods in hot water, sun-drying them, and allowingthem to ‘‘sweat’’ in straw. The cured pods are then soaked inalcohol to produce a product known as pure vanilla extract.The primary constituent in pure vanilla extract is vanillin,which gives the product its flavor. The process of extractingpure vanilla from seed pods may take as long as nine months.

Some people prefer a vanilla product that contains no, oralmost no, alcohol. If alcohol is removed, almost pure vanillais left behind, leaving a product known as natural vanillaflavoring.

Vanilla can also be extracted from plants other thanVanilla planifolia, such as potato peels and pine tree sap.The most economical source of the product, however, is wastematerial left over from the wood pulp industry. That wastematerial consists primarily of lignin, a complex natural poly-mer that, along with cellulose, is the primary component ofwood. The wastes from wood pulping can be treated to breakdown and separate the lignin. This leaves behind a complex

Vanillin. Red atomsare oxygen; white atoms are

hydrogen; and black atoms arecarbon. Gray stick indicatesdouble bond; striped sticks

indicate benzene ring.P U B L I S H E R S R E S O U R C E G R O U P


VANILLIN

mixture, a major component of which is vanilla. This vanillais called lignin vanilla and has many of the same physicalproperties as natural vanilla. Since it is so much less expen-sive to make, it has become one of the major forms of vanillaused by consumers. Lignin vanilla is known commercially asartificial vanilla flavoring.

The two forms of vanilla described earlier—naturalvanilla and lignin vanilla—are mixtures in which the com-pound vanillin is a major component. In both mixtures, othercomponents are present in lesser amounts. These compo-nents may add somewhat different flavors and aromas, mod-ifying the pure taste and smell of vanillin. Artificial methodsfor the production of pure vanillin have been available sincethe late 1890s. The most popular of those methodsbegins with eugenol ((C3H5)C6H3(OH)OCH3) or isoeugenol((CH3CHCH)C6H3(OH)OCH3). Either of these compounds isthen treated with acetic anhydride ((CH3CO)2O) to obtainvanillin acetate, which is then converted to pure vanillin.The product of this reaction, unlike natural vanilla and lig-nin vanilla, is a pure compound, 4-hydroxy-3-methoxybenzal-dehyde, pure vanillin. This method was the primary methodfor making artificial vanillin for more than 50 years. It hassince been replaced by an alternative method of preparation,the Reimer-Tiemann reaction. This method for making arti-ficial vanillin begins with catechol (C6H4(OH)2) or guaiacol(CH3OC6H4OH).

The Remier-Tiemann reaction is also used to produceanother form of vanillin called ethyl vanillin. Ethyl vanillinis the ethyl ether of 4-hydroxybenzoic acid, 4-hydroxy-3-ethoxybenzaldehyde ((CH3CH2O)(OH)C6H3CHO). It is a closechemical relative of natural vanillin in which the methyl(-CH3) group of natural vanillin is replaced by an ethyl(-CH2CH3) group. Ethyl vanillin is also known as artificialvanilla or synthetic vanilla. Its flavor is about three timesas strong as that of methyl vanillin and is used to fortify orreplace natural vanillin and lignin vanillin.


All forms of vanillin are used as a flavoring agent andsweetener in many types of foods, including candies, dessertproducts, ice creams, puddings, yogurts, diet shakes, and softdrinks. It is also added to some wines, alcoholic liquors,


VANILLIN

toothpastes, and cigarettes. The vanillins have also beenshown to stimulate one’s appetite, so they have been usedto treat appetite loss. They are also added to cattle feed toenhance weight gain.

However, less than half the vanillin produced is used infood products. Vanillin’s rich fragrance makes the compounduseful also as an additive in perfumes, air fresheners, soaps,shampoos, candles, creams, lotions, colognes, and ointments.The compound is also used as a raw material in the manufac-ture of a variety of drugs, particularly the compound knownas L-dopa, used to treat Parkinson’s disease.

Vanillin is considered safe for human consumption,although it can be toxic in very large quantities. Knownreactions include respiratory irritation, including coughingand shortness of breath, and gastrointestinal tract irritation.Contact with the skin or eyes can also cause irritation, red-ness, and pain. These symptoms are virtually unknown exceptfor individuals who work directly with the pure compounds.

Interesting Facts

• The tropical orchid Vanilla

planifolia is pollinatednaturally by the tiny Meli-pone bee, native to Mexico.In areas where the beedoes not live, the orchidmust be pollinated artifi-cially by humans.

• Less than 1 percent of thevanillin produced annuallycomes from vanilla beans.The remaining 99 percentcomes from lignin or is pro-duced by synthetic means.

• Small amounts of vanillinare present in the wood usedto make wine casks and addsto the flavor of wine.

• The Coca-Cola Company isbelieved to be the world’slargest buyer of purevanillin. Since the com-pany does not reveal therecipe for its products,that assumption cannotbe confirmed.

• The word vanilla comesfrom the Spanish wordvainilla, meaning ‘‘littlesheath,’’ which refers tothe shape of the vanillaorchid.


VANILLIN


‘‘All about Vanilla Extracts and Flavors.’’ The Vanilla.COMpany.http://www.vanilla.com/html/facts extracts.html (accessed onNovember 19, 2005).

‘‘Aroma Chemicals from Petrochemical Feedstocks.’’ National Economic and Development Council of South Africa.http://www.nedlac.org.za/research/fridge/aroma/part3/benchmarking.pdf (accessed on November 19, 2005).

‘‘Food Guide Question.’’ Gloucester Muslim Welfare Association.http://www.gmwa.org.uk/foodguide2/viewquestion.php?foodqid=69&catID=1&compID=1 (accessed on November 19, 2005).

Rain, Patricia. Vanilla: A Cultural History of the World’s Most

Popular Flavor and Fragrance. Edited by Jeremy P. Tarcher.New York: Penguin Group USA, 2004.

‘‘Vanillin.’’ Greener Industry.http://www.uyseg.org/greener_industry/pages/vanillin/1Vanillin_AP.htm (accessed on November 19, 2005).


VANILLIN

OTHER NAMES:Hydrogen oxide;

dihydrogen oxide

FORMULA:H2O or HOH

ELEMENTS:Hydrogen, oxygen

COMPOUND TYPE:Inorganic

STATE:Liquid




SOLUBILITY:Soluble in ethylalcohol, methyl

alcohol, and acetone

Water

KE

YF

AC

TS

OVERVIEW

Water is a colorless, odorless, tasteless liquid that alsooccurs commonly in the solid state (as ice) and in the gaseousstate (as steam or water vapor). It is a very stable compound thatundergoes a number of important reactions. It reacts with somemetals to form elemental hydrogen and an inorganic base. Withsome metals, such as sodium and potassium, the reaction isquite violent. With other metals, such as iron, the reactionoccurs only very slowly. Water is also a weak electrolyte, ioniz-ing to form hydrogen ions (H+) and hydroxide ions (OH–). Thehydrogen ions occur in solution as hydronium ions (H3O+).

Water is also a strong dipole. A dipole is a molecule inwhich electrical charges are sufficiently separated from eachother that one part of the molecule is negatively charged andanother part, positively charged. Water’s dipole character isresponsible for many of its special characteristics. The posi-tive end of one water molecule is attracted to the negativeend of a second water molecule, resulting in the formation ofa weak (‘‘hydrogen’’) bond between the two molecules.

OHH


For example, water has a very high boiling point for asubstance with relatively small molecules. The high boil-ing point is a result of the fact that heat added to watermust first be used to break hydrogen bonds between watermolecules before providing enough energy to vaporize themolecules. Similarly, the phenomenon known as surfacetension is caused by hydrogen bonding. Surface tensionis the tendency of a liquid to act as if it is covered with athin film. Some insects are able to walk on water becauseits surface tension is so great. The surface tension iscaused by the attractive forces between adjacent watermolecules.

Water is also an excellent solvent. A solvent is a sub-stance capable of dissolving other substances. Chemistssometimes refer to water as ‘‘the universal solvent’’ becauseit is able to dissolve so many other substances. That state-ment is an exaggeration, but does reflect the compound’sability to dissolve more substances that probably any othersingle compound. Water’s ability to dissolve other sub-stances is at least partly a result of its strong dipole char-acter. The positive or negative end of a water moleculeattaches itself to the negative or positive end of the sub-stance to be dissolved. The force of attraction exerted bythe water molecule is sufficient to tear apart the particles ofwhich the second substance is composed causing them todissolve in the water.

Water. Red atom is oxygen andwhite atoms are hydrogen.



WATER

HOW IT IS MADE

Water can be made by a variety of chemical reactions,including:

• The oxidation of hydrogen: 2H2 + O2 ! 2H2O;

• The reaction between an acid and a base, as, forexample: NaOH + HCl ! NaCl + H2O;

• The combustion of an organic material, as, for example:CH4 + 2O2 ! CO2 + 2H2O.

Because water occurs so abundantly, none of thesereactions is required for the commercial production of thecompound. Water makes up about 70 percent of the Earth’ssurface in the oceans, lakes, rivers, ponds, glaciers, ice caps,and other reservoirs. The problem is that only a very smallfraction of that water—about 3 percent—is fresh water. Theremaining 97 percent is salt water. And even the 3 percent offresh water in lakes, rivers, and other resources is impure, inthe sense that it contains other substances dissolved andsuspended in it.

Interesting Facts

• When water freezes, theattractive forces betweenmolecules force them intoa regular crystalline pat-tern that occupies morespace than do the samewater molecules in theliquid state. In otherwords, water expands whenit freezes and ice is lessdense than liquid water.

• One consequence of thatfact is that lakes freezefrom the top down. As iceforms, it floats to the sur-face of the liquid. Aquaticorganisms in the lake are

able to live through thewinter because of the layerof ice on top of the lake.

• Adding to the protectionadded by the layer of ice isthe fact that ice is one ofthe best thermal (heat)insulators known. That is,heat flows through icemore slowly than throughalmost any other sub-stance. Any heat left in afreezing lake will be con-served within the watersince it escapes so slowlythrough the ice layer.


WATER

Thus, the primary concern in obtaining adequate sup-plies of pure water for household, personal, commercial,industrial, or other uses is the purification of water, not itssynthesis. Purification of water is achieved by a number ofprocesses, including chlorination, filtration, distillation, orpurification by some type of ion exchange mechanism.


One of the most important uses of water is the survivalof life on Earth. All plants and animals contain a high pro-portion of water. That proportion ranges from as high as 97percent in many fruits and vegetables to a low of about 20percent in some ‘‘dry’’ foods like breads and cereals. Thehuman body itself comprises anywhere from 50 to 70 percentof a person’s body weight. That water plays a number of roles,such as providing a solvent by which nutrients are circulatedthroughout the body and making possible all kinds of che-mical reactions that occur in aqueous solutions, but do notoccur in the dry state.

Although easy to ignore, water plays an almost unlimitednumber of roles in industrial, chemical, commercial, andother operations. Among these applications of water are:

• As a coolant in electricity generating plants, petroleumrefineries, chemical plants, and many kinds of indus-trial factories;

• For irrigation;

• For cleaning, washing, and scouring raw materials andfinished products;

• As a source of hydrogen and oxygen for many industrialand chemical operations;

• As a solvent for many types of industrial and chemicalreactions and for the extraction of compounds frommixtures;

• In the manufacture of many kinds of foods and bev-erages, such as beer, wine, and soft drinks;

• As a medium for suspending materials in industrialprocesses, such as the manufacture of paper;

• In the processing of textiles;

• For the generation of steam to power industrial, house-hold, and chemical processes;


WATER

• For the hydration of lime;

• As a coolant in nuclear reactors;

• In the transport of industrial and chemical raw materi-als and products;

• For the removal of barks from logs in the timber industry;

• To make possible hydrolysis reactions in chemical andindustrial operations;

• In the manufacture of Portland cement; and

• To dilute solutions that are too concentrated for somegiven industrial process.


‘‘Iowa Project WET.’’ Iowa Academy of Science.http://www.uni.edu/~iowawet/iowawet.html (accessed onNovember 19, 2005).

Strange, Veronica. The Meaning of Water. Oxford, UK: Berg Publishers, 2004.

‘‘Water Properties.’’ London South Bank University.http://www.lsbu.ac.uk/water/data.html (accessed on November19, 2005).

‘‘Water Science for Schools.’’ U.S. Geological Survey.http://ga.water.usgs.gov/edu/ (accessed on November 19,2005).

Words to Know


ELECTROLYTE A substance which, whendissolved in water, will conduct anelectric current.



WATER

OTHER NAMES:Chinese white; philo-

sopher’s wool; zincwhite; flowers of zinc

FORMULA:ZnO

ELEMENTS:Zinc, oxygen


(inorganic)

STATE:Solid





soluble in dilute acids

Zinc Oxide

KE

YF

AC

TS

OVERVIEW

Zinc oxide (ZINC OX-side) is a white to gray to yellowishpowder with no odor but a bitter taste. It occurs in nature asthe mineral zincite. Zinc oxide is perhaps best known as aningredient in cosmetics, personal care products, medicines,and sunscreens. In terms of volume, however, a number ofindustrial applications are of greater importance.

HOW IT IS MADE

Three commercial methods of preparation are availablefor zinc oxide. Two of these methods are known as thermalprocedures because they involve heating either zinc metal oran ore of zinc to obtain zinc vapor. The zinc vapor is thenreacted with oxygen to produce zinc oxide. The formula forthis reaction is 2Zn + O2 ! 2ZnO

The third method is called a ‘‘wet’’ procedure because ittakes place in aqueous solution. In this process, zinc com-pounds are leached out of ores and converted to basic zinc

OZn


carbonate (ZnCO3�2Zn(OH)2). Leaching is a process by whichsoluble salts are dissolved out of soil, ore, or some othermaterial. The basic zinc carbonate is decomposed by heat,yielding pure zinc oxide:

ZnCO3�2Zn(OH)2 ! 3ZnO + CO2 + 2H2O


One of zinc oxide’s most important uses historically is inpaints and pigments. Common names by which it is nowknown, such as Chinese white and zinc white, are terms longused by artists for the compound. White paints and pigmentsmade with zinc oxide retain their luster and purity longerthan most other types of white paints, partly because zincoxide does not react readily with hydrogen sulfide in air thatcauses most white paints to darken.

One of zinc oxide’s most important properties is itsability to absorb ultraviolet (UV) light in sunlight. Becauseof this property, zinc oxide is often added to sunscreensand sunblocks to help protect a person from sunburn. Thesame property accounts for other important applicationsfor zinc oxide, such as their use in rubber and plasticproducts. By absorbing ultraviolet light, zinc oxide pro-tects the rubber or plastic from decomposing. The com-pound also has other applications in the rubber and plasticindustries, including:

• In the curing of natural and synthetic rubber products,increasing the rate at which the product reaches itsfinal chemical state;

Zinc oxide. Red atoms areoxygen and turquoise atomsare zinc. Gray sticks indicatedouble bonds. P U B L I S H E R S



ZINC OXIDE

• As a fungicidal additive to rubber and plastic, prevent-ing fungi from attacking and destroying products madefrom those materials;

• To increase the temperature at which rubber and plasticproducts remain stable and the amount of exposure tolight they can withstand;

• To maintain the proper acidic properties of a product,reducing the rate at which the are likely to decay;

• To provide additional strength to the rubber or plasticproduct.

Besides its major uses in the rubber and plastic indus-tries, zinc oxide has a number of applications in other fields,such as:

• As an additive in glass and ceramic materials, to pro-vide greater heat resistance, greater resistance tobreakage by shock, and high luster;

• In the manufacture of specialized types of sealants andadhesives;

• As a light-gathering agent in photocopy machines;

• As an additive in lubricants for the purpose of reducingwear and helping the lubricant withstand high pres-sures;

• In smokestacks as an aid in removing sulfur dioxideand other pollutant gases produced in factory opera-tions; and

Interesting Facts

• The term philosopher’s

wool dates to the periodof alchemy when scholarsoften gave picturesqueand descriptive namesto the substances withwhich they worked.Philosopher’s woolreferred to the fluffy

white material that wasformed when alchemists(also known as naturalphilosophers) heatedzinc in air. The substancewas also referred to asnix alba, or ‘‘white snow’’for the same reason.


ZINC OXIDE

• In the manufacture of specialized packaging materials,especially those used for food products, because of thecompound’s ability to kill certain microorganisms thatcause food decay.

In moderate amounts, zinc oxide is a relatively harmlesscompound. Exposure to zinc oxide dust may cause respira-tory problems, such as coughing, upper respiratory tractirritation, chills, fever, nausea, and vomiting.


‘‘Application.’’ Nav Bahrat Metallic Oxides Industries.http://www.navbharat.co.in/clients.htm (accessed on November19, 2005).

‘‘Occupational Safety and Health Guideline for Zinc Oxide.’’ Occupational Safety & Health Administration.http://www.osha.gov/SLTC/healthguidelines/zincoxide/recognition.html (accessed on November 19, 2005).

‘‘Zinc Oxide.’’ Center for Advanced Microstructures and Devices,Louisiana State University.http://www.camd.lsu.edu/msds/z/zinc_oxide.htm (accessed onNovember 19, 2005).

‘‘Zinc Oxide Producers Association.’’http://www.cefic.be/Templates/shwAssocDetails.asp?NID=5&HID=25&ID=172 (accessed on November 19, 2005).

Words to Know




ZINC OXIDE

p cesappendicesLists of compounds




CHEMICAL COMPOUNDS

li

Compounds byFormula

AgISilver Iodide

AgNO3

Silver Nitrate

Ag2OSilver(I) Oxide

Ag2SSilver(I) Sulfide

AlF3Aluminum Fluoride

Al(OH)3Aluminum Hydroxide

Al2O3

Aluminum Oxide

CCl2F2Dichlorodifluoromethane

CCl4Carbon Tetrachloride

-[-CF2-]-nPolytetrafluoroethylene

CH�CHAcetylene

-[-CH(CH3)CH2-]-nPolypropylene

CHCl3Chloroform

CH2OFormaldehyde

-[-CH2C(CH3)(COOH)CH2-]-nPolymethyl Methacrylate

CH2=C(CN)COOCH3

Cyanoacrylate

CH2=CHCH=CH2

1,3-Butadiene

CH2=CHCH3

Propylene

CH2=CH(CH3)CH=CH2

Isoprene

-[-CH2-CH(COONa)-]n-Sodium Polyacrylate

-[CH2CHC6H5-]n-[-CH2CH=CHCH2-]n-[CH2CHC6H

Poly(Styrene-Butadiene-Styrene)

-[-CH2CHCl-]-nPolyvinyl Chloride

CH2=CH2

Ethylene

(CH2CH2Cl)2S2,20-Dichlorodiethyl Sulfide

CHEMICAL COMPOUNDS

liii

-[-CH2-CH2-]-nPolyethylene

-[-CH2C6H5-]-nPolystyrene

CH2NO2CHNOCH2NO2

Nitroglycerin

CH2OHCHOHCH2OHGlycerol

CH2OHCH2OHEthylene Glycol

(CH2)2OEthylene Oxide

CH3CHOHCH3

Isopropyl Alcohol

CH3CHOHCOOHLactic Acid

CH3CH2OHEthyl Alcohol

CH3COCH3

Dimethyl Ketone

CH3CONHC6H4OHAcetaminophen

CH3COOCH2CH2CH(CH3)2Isoamyl Acetate

CH3COOC2H5

Ethyl Acetate

CH3COOC5H11

Amyl Acetate

CH3COOC6H4COOHAcetylsalicylic acid

CH3COOHAcetic acid

CH3C5HN(OH)(CH2OH)2Pyridoxine

CH3C6H9 (C3H7)OHMenthol

CH3OHMethyl Alcohol

(CH3O)(OH)C6H3CHOVanillin

CH3SHMethyl Mercaptan

(CH3)2CHCH2CH2NO2

Amyl Nitrite

C5H11NO2

Amyl Nitrite

(CH3)2C5H3NSO(COOH)NHCORPenicillin

(CH3)3COCH3

Methyl-t-butyl Ether

CH4

Methane

CH4SMethyl Mercaptan

COCarbon Monoxide

-[-CO(CH2)4CO-NH(CH2)6NH-]-nNylon 6 and Nylon 66

-[-CO(CH2)5NH-]-nNylon 6 and Nylon 66

-[-CONH-C6H4-NCOO-CH2CH2-O-]-n

Polyurethane

COOH(CH2)2CH(NH2)COONaMonosodium Glutamate

CO2

Carbon Dioxide

C2H2

Acetylene

C2H2O4

Oxalic Acid

[C2H3Cl]nPolyvinyl Chloride

C2H4

Ethylene

[C2H4]nPolyethylene

C2H4OEthylene Oxide

C2H4O2

Acetic acid

C2H6OEthyl Alcohol

C2H6O2

Ethylene Glycol

[C3H3O2Na]nSodium Polyacrylate

C3H5N3O5

Nitroglycerin

[C3H6]nPolypropylene

C3H6ODimethyl Ketone

C3H6O3

Lactic Acid

C3H8

Propane

C3H8OIsopropyl Alcohol

C3H8O3

Glycerol

C4H6

1,3-Butadiene

C4H8Cl2S2,20-Dichlorodiethyl Sulfide

C4H8O2

Ethyl Acetate

C4H10

Butane

Compounds by Formula

liv CHEMICAL COMPOUNDS

C4H10SButyl Mercaptan

C5H4NC4H7NCH3

Nicotine

C5H5NO2

Cyanoacrylate

C5H8

Isoprene

[C5H8]nPolymethyl Methacrylate

C5H8NNaO4

Monosodium Glutamate

C5H12OMethyl-t-butyl Ether

C6H2(CH3)(NO2)32,4,6-Trinitrotoluene

C6H3ClOH-O-C6H3Cl2Triclosan

C6H3Cl2NHCONHC6H4ClTriclocarban

C6H5CH=CHCHOCinnamaldehyde

C6H5CH=CH2

Styrene

C6H5CH(CH3)2Cumene

C6H5CH3

Toluene

C6H5COOHBenzoic Acid

C6H5C2H5

Ethylbenzene

C6H5NO2

Niacin

C6H5OHPhenol

C6H6

Benzene

C6H6Cl6Gamma-1,2,3,4,5,6-Hexa-

chlorocyclohexane

C6H6OPhenol

[C6H7O2(OH)2OCS2Na]nCellulose Xanthate

C6H8O6

Ascorbic Acid

C6H8O7

Citric Acid

(C6H10O5)nCellulose

[C6H11NO]nNylon 6 and Nylon 66

C6H11NHSO3NaSodium Cyclamate

C6H12NNaSO3

Sodium Cyclamate

C6H12O2

Butyl Acetate

C6H12O6

FructoseGlucose

C6H14

Hexane

C6H4(CH3)CON(C2H5)2N,N-Diethyl-3-Methylbenza-

mide

C7H5NO3SSaccharin

C7H5N3O6

2,4,6-Trinitrotoluene

C7H6O2

Benzoic Acid

[C7H7]nPolystyrene

C8H7N3O2

Luminol

C7H8N4O2

Theobromine

[C7H11NaO5S2]nChloroform

C7H14O2

Isoamyl AcetateAmyl Acetate

C8H8

Styrene

[C8H8]n-[C4H6]n-[C8H8]nPoly(Styrene-Butadiene-

Styrene)

C8H9NO2

Acetaminophen

C8H10

Ethylbenzene

C8H10N4O2

Caffeine

C8H11NO3

Pyridoxine

C9H8OCinnamaldehyde

C9H8O4

Acetylsalicylic acid

C9H12

Cumene

C10H8

Naphthalene

C10H14N2

Nicotine

C10H16OCamphor

CHEMICAL COMPOUNDS lv


C10H20OMenthol

C11H16O2

Butylated Hydroxyanisoleand Butylated Hydroxyto-luene (BHA)

C12H7Cl3O2

Triclosan

C12H16N4O18

Cellulose Nitrate

C12H17ClN4OSThiamine

C12H17NON,N-Diethyl-3-Methylbenza-

mide

[C12H22N2O2]nNylon 6 and Nylon 66

C12H22O11

LactoseSucrose

C13H9Cl3N2OTriclocarban

C13H18O2

2-(4-Isobutylphenyl)propionicAcid

C14H9Cl5Dichlorodiphenyltrichloro-

ethane

C14H14O3

Naproxen

C14H18N2O5

L-Aspartyl-L-PhenylalanineMethyl Ester

C15H24OButylated Hydroxyanisole

and Butylated Hydroxyto-luene (BHT)

C16H18N2OSPenicillin

C16H19N3O5SAmoxicillin

C17H20N4O6

Riboflavin

C19H19N7O6

Folic Acid

C19H28O2

Testosterone

C20H30ORetinol

C27H45OHCholesterol

C28H34N2O3

Denatonium Benzoate

C29H50OAlpha-Tocopherol

C35H28O5N4MgChlorophyll


C40H56

Beta-Carotene




C63H88CoN14O14PCyanocobalamin

C76H52O46

Tannic Acid

CaCO3

Calcium Carbonate

CaHPO4

Calcium Phosphate

CaOCalcium Oxide

Ca(OH)2Calcium Hydroxide

CaSO4

Calcium Sulfate

CaSiO3

Calcium Silicate

Ca(H2PO4)2Calcium Phosphate

Ca3(PO4)2Calcium Phosphate

(ClC6H4)2CHCCl3Dichlorodiphenyltrichloro-

ethane

-ClO4

Perchlorates

CuOCopper(II) Oxide

CuSO4

Copper(II) Sulfate

Cu2OCopper(I) Oxide

FeOIron(II) Oxide

Fe2O3

Iron(III) Oxide

HCHOFormaldehyde

HClHydrogen Chloride

HNO3

Nitric Acid

HOHWater

lvi CHEMICAL COMPOUNDS


HOOCCH2C(OH)(COOH)CH2

COOHCitric Acid

HOOCCOOHOxalic Acid

H2OWater

H2O2

Hydrogen Peroxide

H2SO4

Sulfuric Acid

H3BO3

Boric Acid

H3PO4

Phosphoric Acid

HgSMercury(II) Sulfide

KAl(SO4)2Aluminum Potassium

Sulfate

KClPotassium Chloride

KFPotassium Fluoride

KHCO3

Potassium Bicarbonate

KHC4H4O6

Potassium Bitartrate

KHSO4

Potassium Bisulfate

KIPotassium Iodide

KNO3

Potassium Nitrate

KOHPotassium Hydroxide

K2CO3 K34NO15

Potassium Carbonate

K2SO4

Potassium Sulfate

MgCl2Magnesium Chloride

MgOMagnesium Oxide

Mg(OH)2Magnesium Hydroxide

MgSO4

Magnesium Sulfate

Mg3Si4O10(OH)2Magnesium Silicate

Hydroxide

(NH2)2COUrea

NH3

Ammonia

(NH4)2SO4

Ammonium Sulfate

NH4ClAmmonium Chloride

NH4NO3

Ammonium Nitrate

NH4OHAmmonium Hydroxide

NONitric Oxide

NO2

Nitrogen Dioxide

N2ONitrous Oxide

NaBO3

Sodium Perborate

NaC2H3O2

Sodium Acetate

NaClSodium Chloride

NaClOSodium Hypochlorite

NaFSodium Fluoride

NaHCO3

Sodium Bicarbonate

NaH2PO4

Sodium Phosphate

NaOHSodium Hydroxide

Na2B4O7

Sodium Tetraborate

Na2B4O7�10H2OSodium Tetraborate

Na2CO3

Sodium Carbonate

Na2HPO4

Sodium Phosphate

Na2SO3

Sodium Sulfite

Na2S2O3

Sodium Thiosulfate

Na2SiO3

Sodium Silicate

Na3PO4

Sodium Phosphate

SO2

Sulfur Dioxide

SiO2

Silicon Dioxide

SnF2Stannous Fluoride

ZnOZinc Oxide

CHEMICAL COMPOUNDS lvii


Compounds byElement

ALUMINUM

Aluminum FluorideAluminum HydroxideAluminum OxideAluminum Potassium Sulfate

BORON

Boric AcidSodium PerborateSodium Tetraborate

CALCIUM

Calcium CarbonateCalcium HydroxideCalcium OxideCalcium PhosphateCalcium SilicateCalcium Sulfate

CARBON

1,3-Butadiene2-(4-Isobutylphenyl)propionic

Acid2,20-Dichlorodiethyl

Sulfide2,4,6-TrinitrotolueneAcetaminophenAcetic acidAcetyleneAcetylsalicylic acidAlpha-Tocopherol

AmoxicillinAmyl AcetateAmyl NitriteAscorbic AcidBenzeneBenzoic AcidBeta-CaroteneButaneButyl AcetateButyl MercaptanButylated Hydroxyanisole

and ButylatedHydroxytoluene

CaffeineCalcium CarbonateCamphorCarbon DioxideCarbon MonoxideCarbon TetrachlorideCelluloseCellulose NitrateCellulose XanthateChloroformChlorophyllCholesterolCinnamaldehydeCitric AcidCollagenCumeneCyanoacrylateCyanocobalaminDenatonium BenzoateDichlorodifluoromethane

CHEMICAL COMPOUNDS

lix

Dichlorodiphenyltrichloro-ethane

Dimethyl KetoneEthyl AcetateEthyl AlcoholEthylbenzeneEthyleneEthylene GlycolEthylene OxideFolic AcidFormaldehydeFructoseGamma-1,2,3,4,5,6-Hexachloro-

cyclohexaneGelatinGlucoseGlycerolHexaneIsoamyl AcetateIsopreneIsopropyl AlcoholLactic AcidLactoseL-Aspartyl-L-Phenylalanine

Methyl EsterLuminolMentholMethaneMethyl AlcoholMethyl MercaptanMethyl-t-butyl EtherMonosodium GlutamateN,N-Diethyl-3-Methyl-

benzamideNaphthaleneNaproxenNiacinNicotineNitroglycerinNylon 6 and Nylon 66Oxalic AcidPectinPenicillinPetrolatumPetroleumPhenolPoly(Styrene-Butadiene-

Styrene)

PolycarbonatesPolyethylenePolymethyl MethacrylatePolypropylenePolysiloxanePolystyrenePolytetrafluoroethylenePolyurethanePolyvinyl ChloridePotassium BicarbonatePotassium BitartratePotassium CarbonatePropanePropylenePyridoxineRetinolRiboflavinSaccharinSodium AcetateSodium BicarbonateSodium CarbonateSodium CyclamateSodium PolyacrylateStyreneSucroseSucrose PolyesterTannic AcidTestosteroneTheobromineThiamineTolueneTriclocarbanTriclosanUreaVanillin

CHLORINE

2,20-Dichlorodiethyl SulfideAmmonium ChlorideCarbon TetrachlorideChloroformDichlorodifluoromethaneDichlorodiphenyltrichloro-

ethaneGamma-1,2,3,4,5,6-Hexachloro-

cyclohexaneHydrogen Chloride

Magnesium ChloridePerchloratesPolyvinyl ChloridePotassium ChlorideSodium ChlorideSodium HypochloriteThiamineTriclocarbanTriclosan

COBALT

Cyanocobalamin

COPPER

Copper(I) OxideCopper(II) OxideCopper(II) Sulfate

FLUORINE

Aluminum FluorideDichlorodifluoromethanePolytetrafluoroethylenePotassium FluorideSodium FluorideStannous Fluoride

HYDROGEN


Acid2,20-Dichlorodiethyl Sulfide2,4,6-TrinitrotolueneAcetaminophenAcetic acidAcetyleneAcetylsalicylic acidAlpha-TocopherolAmmoniaAmmonium ChlorideAmmonium HydroxideAmmonium NitrateAmmonium SulfateAmoxicillinAmyl AcetateAmyl NitriteAscorbic Acid

Compounds by Element

lx CHEMICAL COMPOUNDS

BenzeneBenzoic AcidBeta-CaroteneBoric AcidButaneButyl AcetateButyl MercaptanButylated Hydroxyanisole and

Butylated HydroxytolueneCaffeineCalcium HydroxideCalcium PhosphateCamphorCelluloseCellulose NitrateCellulose XanthateChloroformChlorophyllCholesterolCinnamaldehydeCitric AcidCollagenCumeneCyanoacrylateCyanocobalaminDenatonium BenzoateDichlorodiphenyltrichloro-

ethaneDimethyl KetoneEthyl AcetateEthyl AlcoholEthylbenzeneEthyleneEthylene GlycolEthylene OxideFolic AcidFormaldehydeFructoseGamma-1,2,3,4,5,6-Hexachloro-

cyclohexaneGelatinGlucoseGlycerolHexaneHydrogen ChlorideIsoamyl AcetateIsopreneIsopropyl Alcohol

Lactic AcidLactoseL-Aspartyl-L-Phenylalanine

Methyl EsterLuminolMagnesium HydroxideMagnesium Silicate

HydroxideMentholMethaneMethyl AlcoholMethyl MercaptanMethyl-t-butyl EtherMonosodium GlutamateN,N-Diethyl-3-Methyl-

benzamideNaphthaleneNaproxenNiacinNicotineNitric AcidNitroglycerinNylon 6 and Nylon 66Oxalic AcidPectinPenicillinPetrolatumPetroleumPhenolPhosphoric AcidPoly(Styrene-Butadiene-

Styrene)PolycarbonatesPolyethylenePolymethyl

MethacrylatePolypropylenePolysiloxanePolystyrenePolyurethanePolyvinyl ChloridePotassium BicarbonatePotassium BisulfatePotassium BitartratePotassium HydroxidePropanePropylenePyridoxine

RetinolRiboflavinSaccharinSodium AcetateSodium BicarbonateSodium CyclamateSodium HydroxideSodium PolyacrylateStyreneSucroseSucrose PolyesterSulfuric AcidTannic AcidTestosteroneTheobromineThiamineTolueneTriclocarbanTriclosanUreaVanillinWater

IODINE

Potassium IodideSilver Iodide

IRON

Iron(II) OxideIron(III) Oxide

MAGNESIUM

ChlorophyllMagnesium ChlorideMagnesium HydroxideMagnesium OxideMagnesium Silicate

HydroxideMagnesium Sulfate

MERCURY

Mercury(II) Sulfide

NITROGEN

2,4,6-TrinitrotolueneAcetaminophen

CHEMICAL COMPOUNDS lxi


AmmoniaAmmonium ChlorideAmmonium HydroxideAmmonium NitrateAmmonium SulfateAmoxicillinAmyl NitriteCaffeineCellulose NitrateChlorophyllCollagenCyanoacrylateCyanocobalaminDenatonium BenzoateFolic AcidGelatinL-Aspartyl-L-Phenylalanine

Methyl EsterLuminolMonosodium GlutamateN,N-Diethyl-3-Methyl-

benzamideNiacinNicotineNitric AcidNitric OxideNitrogen DioxideNitroglycerinNylon 6 and Nylon 66PenicillinPolyurethanePotassium NitratePyridoxineRiboflavinSaccharinSilver NitrateSodium CyclamateTheobromineThiamineTriclocarbanUreaNitrous Oxide

OXYGEN


2,4,6-TrinitrotolueneAcetaminophen

Acetic acidAcetylsalicylic acidAlpha-TocopherolAluminum HydroxideAluminum Potassium SulfateAluminum OxideAmmonium HydroxideAmmonium NitrateAmmonium SulfateAmoxicillinAmyl AcetateAmyl NitriteAscorbic AcidBenzoic AcidBoric AcidButyl AcetateButylated Hydroxyanisole

and Butylated Hydro-xytoluene

CaffeineCalcium CarbonateCalcium HydroxideCalcium OxideCalcium PhosphateCalcium SilicateCalcium SulfateCamphorCarbon DioxideCarbon MonoxideCelluloseCellulose NitrateCellulose XanthateChlorophyllCholesterolCinnamaldehydeCitric AcidCollagenCopper(I) OxideCopper(II) OxideCopper(II) SulfateCyanoacrylateCyanocobalaminDenatonium BenzoateDimethyl KetoneEthyl AcetateEthyl AlcoholEthylene GlycolEthylene Oxide

Folic AcidFormaldehydeFructoseGelatinGlucoseGlycerolHydrogen PeroxideIron(II) OxideIron(III) OxideIsoamyl AcetateIsopropyl AlcoholLactic AcidLactoseL-Aspartyl-L-Phenylalanine

Methyl EsterLuminolMagnesium HydroxideMagnesium OxideMagnesium Silicate

HydroxideMagnesium SulfateMentholMethyl AlcoholMethyl-t-butyl EtherMonosodium GlutamateN,N-Diethyl-3-Methyl-

benzamideNaproxenNiacinNitric AcidNitric OxideNitrogen DioxideNitroglycerinNitrous OxideNylon 6 and Nylon 66Oxalic AcidPectinPenicillinPerchloratesPetroleumPhenolPhosphoric AcidPolycarbonatesPolymethyl MethacrylatePolysiloxanePolyurethanePotassium BicarbonatePotassium Bisulfate

lxii CHEMICAL COMPOUNDS


Potassium BitartratePotassium CarbonatePotassium HydroxidePotassium NitratePotassium SulfatePyridoxineRetinolRiboflavinSaccharinSilicon DioxideSilver NitrateSilver(I) OxideSodium AcetateSodium BicarbonateSodium CarbonateSodium CyclamateSodium HydroxideSodium HypochloriteSodium PerborateSodium PhosphateSodium PolyacrylateSodium SilicateSodium SulfiteSodium TetraborateSodium ThiosulfateSucroseSucrose PolyesterSulfur DioxideSulfuric AcidTannic AcidTestosteroneTheobromineThiamineTriclocarbanTriclosanUreaVanillinWaterZinc Oxide

PHOSPHORUS

Calcium Phosphate

Phosphoric AcidSodium Phosphate

POTASSIUM

Aluminum PotassiumSulfate

Potassium BicarbonatePotassium BisulfatePotassium BitartratePotassium CarbonatePotassium ChloridePotassium FluoridePotassium HydroxidePotassium IodidePotassium NitratePotassium Sulfate

SILICON

Calcium SilicateMagnesium Silicate

HydroxidePolysiloxaneSilicon DioxideSodium Silicate

SILVER

Silver IodideSilver NitrateSilver(I) OxideSilver(I) Sulfide

SODIUM

Cellulose XanthateMonosodium GlutamateSodium AcetateSodium BicarbonateSodium CarbonateSodium ChlorideSodium FluorideSodium Hydroxide

Sodium HypochloriteSodium PerborateSodium PhosphateSodium PolyacrylateSodium SilicateSodium SulfiteSodium TetraborateSodium Thiosulfate

SULFUR

2,20-DichlorodiethylSulfide

Aluminum PotassiumSulfate

Ammonium SulfateAmoxicillinButyl MercaptanCalcium SulfateCellulose XanthateCopper(II) SulfateMagnesium SulfateMercury(II) SulfideMethyl MercaptanPenicillinPotassium BisulfatePotassium SulfateSaccharinSilver(I) SulfideSodium CyclamateSodium SulfiteSodium ThiosulfateSulfur DioxideSulfuric AcidThiamine

TIN

Stannous Fluoride

ZINC

Zinc Oxide

CHEMICAL COMPOUNDS lxiii


Compounds byType

ACID


Acetic acidAcetylsalicylic acidAscorbic AcidBenzoic AcidBoric AcidButyl AcetateCitric AcidDenatonium BenzoateFolic AcidHydrogen ChlorideLactic AcidNaproxenNiacinNitric AcidOxalic AcidPenicillinPhosphoric AcidPotassium BicarbonatePotassium BisulfatePotassium BitartrateSodium BicarbonateSulfuric AcidTannic Acid

ALCOHOL

Ethyl AlcoholEthylene GlycolGlycerolIsopropyl Alcohol

MentholMethyl AlcoholRetinol

ALDEHYDE

CinnamaldehydeFormaldehyde

ALKALOID

CaffeineNicotineTheobromine

ALKANE

ButaneHexaneMethanePropane

ALKENE

1,3-ButadieneEthylenePropylene

ALKYNE

Acetylene

AMIDE

Acetaminophen

CHEMICAL COMPOUNDS

lxv

BASE

Aluminum HydroxideAmmoniaAmmonium HydroxideCaffeineCalcium HydroxideMagnesium HydroxidePotassium HydroxideSodium HydroxideTheobromine

CARBOHYDRATE

CelluloseCellulose NitrateFructoseGlucoseLactoseSucrose

CARBOXYLIC ACID

Acetic acidAcetylsalicylic acidButyl AcetateCitric AcidLactic AcidNaproxenNiacinOxalic Acid

ESTER

Amyl AcetateAmyl NitriteCyanoacrylateEthyl AcetateIsoamyl AcetateL-Aspartyl-L-Phenylalanine

Methyl EsterNitroglycerin

ETHER

Ethylene OxideMethyl-t-butyl EtherVanillin

HYDROCARBON

1,3-ButadieneAcetyleneBenzeneBeta-CaroteneButaneCumeneEthylbenzeneEthyleneHexaneIsopreneMethaneNaphthalenePropanePropyleneStyreneToluene

INORGANIC

Aluminum FluorideAluminum HydroxideAluminum OxideAluminum Potassium SulfateAmmoniaAmmonium ChlorideAmmonium HydroxideAmmonium NitrateAmmonium SulfateBoric AcidCalcium CarbonateCalcium HydroxideCalcium OxideCalcium PhosphateCalcium SilicateCalcium SulfateCarbon DioxideCarbon MonoxideCopper(I) OxideCopper(II) OxideCopper(II) SulfateHydrogen ChlorideIron(II) OxideIron(III) OxideMagnesium ChlorideMagnesium HydroxideMagnesium Oxide

Magnesium Silicate HydroxideMagnesium SulfateMercury(II) SulfideNitric AcidNitric OxideNitrogen DioxideNitrous OxidePerchloratesPhosphoric AcidPolysiloxanePotassium BicarbonatePotassium BisulfatePotassium BitartratePotassium CarbonatePotassium ChloridePotassium FluoridePotassium HydroxidePotassium IodidePotassium NitratePotassium SulfateSilicon DioxideSilver IodideSilver NitrateSilver(I) OxideSilver(I) SulfideSodium AcetateSodium BicarbonateSodium CarbonateSodium ChlorideSodium FluorideSodium HydroxideSodium HypochloriteSodium PerborateSodium PhosphateSodium SilicateSodium SulfiteSodium TetraborateSodium ThiosulfateStannous FluorideSulfur DioxideSulfuric AcidWaterZinc Oxide

KETONE

CamphorDimethyl Ketone

Compounds by Type

lxvi CHEMICAL COMPOUNDS

METALLIC OXIDE

Aluminum OxideCalcium OxideCopper(I) OxideCopper(II) OxideIron(II) OxideIron(III) OxideMagnesium OxideSilver(I) OxideZinc Oxide

NONMETALLIC OXIDE

Carbon DioxideCarbon MonoxideHydrogen PeroxideNitric OxideNitrogen DioxideNitrous OxideSilicon DioxideSulfur Dioxide

ORGANIC


Acid2,20-Dichlorodiethyl Sulfide2,4,6-TrinitrotolueneAcetaminophenAcetic acidAcetyleneAcetylsalicylic acidAlpha-TocopherolAmoxicillinAmyl AcetateAmyl NitriteAscorbic AcidBenzeneBenzoic AcidBeta-CaroteneButaneButyl AcetateButyl MercaptanButylated Hydroxyanisole and

Butylated HydroxytolueneCaffeineCamphor

Carbon TetrachlorideCelluloseCellulose NitrateCellulose XanthateChloroformChlorophyllCholesterolCinnamaldehydeCitric AcidCollagenCumeneCyanoacrylateCyanocobalaminDenatonium

BenzoateDichlorodifluoromethaneDichlorodiphenyltrichloro-

ethaneDimethyl KetoneEthyl AcetateEthyl AlcoholEthylbenzeneEthyleneEthylene GlycolEthylene OxideFolic AcidFormaldehydeFructoseGamma-1,2,3,4,5,6-Hexachloro-

cyclohexaneGlucoseGlycerolHexaneHydrogen PeroxideIsoamyl AcetateIsopreneIsopropyl AlcoholLactic AcidLactoseL-Aspartyl-L-Phenylalanine

Methyl EsterLuminolMentholMethaneMethyl AlcoholMethyl MercaptanMethyl-t-butyl EtherMonosodium Glutamate

N,N-Diethyl-3-Methylbenza-mide

NaphthaleneNaproxenNiacinNicotineNitroglycerinNylon 6 and Nylon 66Oxalic AcidPenicillinPhenolPoly(Styrene-Butadiene-

Styrene)PolycarbonatesPolyethylenePolymethyl MethacrylatePolypropylenePolystyrenePolytetrafluoroethylenePolyurethanePolyvinyl ChloridePropanePropylenePyridoxineRetinolRiboflavinSaccharinSodium CyclamateSodium PolyacrylateStyreneSucroseSucrose PolyesterTannic AcidTestosteroneTheobromineThiamineTolueneTriclocarbanTriclosanUreaVanillin

PHENOL

Butylated Hydroxyanisoleand Butylated Hydroxy-toluene

Phenol

CHEMICAL COMPOUNDS lxvii

Compounds by Type

POLYMER

CelluloseCellulose NitrateCellulose XanthateNylon 6 and Nylon 66Poly(Styrene-Butadiene-

Styrene)PolycarbonatesPolyethylenePolymethyl MethacrylatePolypropylenePolysiloxanePolystyrenePolytetrafluoroethylenePolyurethanePolyvinyl ChlorideSodium Polyacrylate

SALT

Aluminum FluorideAluminum Potassium SulfateAmmonium ChlorideAmmonium NitrateAmmonium Sulfate

Calcium CarbonateCalcium PhosphateCalcium SilicateCalcium SulfateCopper(II) SulfateMagnesium ChlorideMagnesium Silicate

HydroxideMagnesium SulfateMercury(II) SulfideMonosodium GlutamatePerchloratesPotassium BicarbonatePotassium BisulfatePotassium BitartratePotassium CarbonatePotassium ChloridePotassium FluoridePotassium IodidePotassium NitratePotassium SulfateSilver IodideSilver NitrateSilver(I) SulfideSodium Acetate

Sodium BicarbonateSodium CarbonateSodium ChlorideSodium CyclamateSodium FluorideSodium HypochloriteSodium PerborateSodium PhosphateSodium SilicateSodium SulfiteSodium TetraborateSodium ThiosulfateStannous Fluoride

VITAMIN

Alpha-TocopherolAscorbic AcidCyanocobalaminFolic AcidNiacinPyridoxineRetinolRiboflavinThiamine

lxviii CHEMICAL COMPOUNDS

Compounds by Type

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lxxii CHEMICAL COMPOUNDS


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CHEMICAL COMPOUNDS lxxiii


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lxxiv CHEMICAL COMPOUNDS


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CHEMICAL COMPOUNDS lxxv


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lxxvi CHEMICAL COMPOUNDS


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CHEMICAL COMPOUNDS lxxvii


indexindexThis index is sorted

word by word. Italictype indicates volume

numbers; boldface

indicates main

entries; (ill.) indicates

illustrations.•AAbbott Laboratories, 3:742Abrasives, 1:50Acetaminophen, 1:19-22, 20 (ill.)Acetic acid, 1:23-26, 24 (ill.)Acetone, 1:289–291Acetylene, 1:27-30, 28 (ill.)Acetylsalicylic acid, 1:31-35, 32 (ill.)Acid rain, 1:149, 153; 2:499; 3:822Activated charcoal, 2:457Adenosine, 1:140Advil, 1:11Alarm pheromones, 1:127Albrecht, H.O., 2:407Alcohol, 2:297–301, 449–453Aleve, 2:477Alka-Seltzer, 3:726Alkenes, 2:307–311Alpha-tocopherol, 1:37-40, 38 (ill.)Aluminum fluoride, 1:41-44, 42 (ill.)Aluminum hydroxide, 1:45-48, 46 (ill.), 50Aluminum metal, 1:42, 50–51Aluminum oxide, 1:49-52, 50 (ill.)Aluminum potassium sulfate, 1:53-56, 54 (ill.)

CHEMICAL COMPOUNDS

lxxix

Amatol, 1:18

Ammonia, 1:57-61, 58 (ill.), 69–71,73–74; 2:446; 3:761–762, 868–869

Ammonia-soda process, 1:64

Ammonium chloride, 1:63-67, 64 (ill.)

Ammonium hydroxide, 1:69-71, 70 (ill.)

Ammonium nitrate, 1:73-76, 74 (ill.); 2:495

Ammonium perchlorate, 2:541–542

Ammonium sulfate, 1:77-80, 78 (ill.)

Amoxicillin, 1:81-84, 82 (ill.)

Amyl acetate, 1:85-88, 86 (ill.)

Amyl nitrite, 1:89-92, 90 (ill.)

Analgesics, 1:9–13, 19–22, 31–34

Andrews, Edmund, 2:514

Anesthetics, 1:211–212; 2:514–515

ANFO (Ammonium nitrate fuel oil), 1:75

Angina, treatment of, 1:90

Anhydrous calcium sulfate, 1:165–169

Animal feeds, 3:652, 661, 870

Antacids

aluminum hydroxide, 1:45–46

calcium carbonate, 1:144

magnesium hydroxide, 2:416–417

potassium bicarbonate, 3:621–622

sodium bicarbonate, 3:726

Anti-inflammatories, 1:9

Antibiotics, 1:81–84; 2:535–539

Antifouling agents, 1:248

Antifreeze, 2:315

Antioxidants, 1:38, 110, 135

Antiseptics, 1:117, 261; 2:365;3:652, 859–865

Arm & Hammer, 3:724

Armstrong, Henry E., 1:1

Aromatic hydrocarbons, 1:255–258;2:303–306

Ascorbic acid, 1:93-97, 94 (ill.)

Aspartame, 2:401–405

Asphyxiants, 1:27–30

Aspirin, 1:31–35

Astringents, 1:54; 3:834

Atlantic Richfield Corp., 2:459

Avery, Charles E., 2:392

Azeotropic mixtures, 2:459–461

•B

Bad breath, 2:457Baekeland, Leo Hendrik, 2:561Baking soda, 3:723–727Banks, Robert, 2:580, 582, 588Baratol, 1:18Barnes, W., 1:271BASF Corp., 1:28; 3:598Bauxite, 1:45, 49Bayer, Otto, 3:610Bayer AG Co., 1:33; 2:576Beadle, Clayton, 1:196, 207Beecham lab, 1:83Bees, 2:379Beguin, Jean, 1:289Ben-Gay, 1:173Benzene, 1:99-103, 100 (ill.); 3:855Benzoic acid, 1:105-108, 106 (ill.)Beriberi, 3:847–851Berthollet, Claude Louis, 1:57; 3:760Berzelius, Jons Jakob, 3:853Beta-carotene, 1:109-113, 110 (ill.); 3:678–680Bevan, Edward John, 1:196, 207B.F. Goodrich, 2:384; 3:616–617BHA, 1:133–136BHT, 1:133–136Bishop, Katherine Scott, 1:38Bitrex, 1:271–274Black, Joseph, 1:151, 177–178Black Leaf 40, 2:489Black mercury(II) sulfide, 2:439–442Bleaches, 2:365; 3:761, 796, 820Block copolymers, 2:571–574Blyth, Alexander Wynter, 3:683Bock, Walter, 2:572Bondt, N., 2:307Boots Co., 1:9–11Borax, 1:116; 3:789–792Boric acid, 1:115-118, 116 (ill.)Bosch, Carl, 1:58Boyle, Robert, 2:451, 513; 3:659Braconnot, Henri, 1:196Breast implants, 2:594Bristol-Meyers, 1:11Brown-Sequard, 3:837–838

Index

lxxx CHEMICAL COMPOUNDS

Brucite, 2:415Brunton, Sir Thomas Lauder, 2:508Buchner, Johann, 1:32Buffering agents, 3:721Building products, chemicals in

calcium carbonate, 1:145calcium hydroxide, 1:148calcium silicate, 1:162–163, 167–168polystyrene, 3:599polyvinyl chloride, 3:618silicon dioxide, 3:698

Bussy, Antoine, 1:289Butane, 1:119-123, 120 (ill.)Butenandt, Adolf Friedrich Johann, 3:838Butlerov, Alexander Mikhailovich, 2:325Butyl acetate, 1:125-128, 126 (ill.)Butyl mercaptan, 1:129-132, 130 (ill.)Butylated hydroxyanisole (BHA), 1:133-136,

134 (ill.)Butylated hydroxytoluenene (BHT), 1:133-136,

134 (ill.)

•CCaffeine, 1:137-141, 138 (ill.); 3:843–846Calcium carbonate, 1:143-146, 144 (ill.), 151–152,

178Calcium hydroxide, 1:147-150, 148 (ill.)Calcium magnesium acetate, 1:25Calcium oxide, 1:151-155, 152 (ill.)Calcium phosphate, 1:155-159, 156 (ill.)Calcium silicate, 1:161-164, 162 (ill.)Calcium sulfate, 1:165-169, 166 (ill.)Calcium sulfate dihydrate, 1:165–169Calcium sulfate hemihydrate, 1:165–169Campho-phenique, 1:173Camphor, 1:171-175, 172 (ill.)Carbohydrates. See SugarsCarbolic acid, 2:559–563Carbon dioxide, 1:177-181, 178 (ill.)Carbon monoxide, 1:183-187, 184 (ill.)Carbon tetrachloride, 1:189-193, 190 (ill.)Carbonation of beverages, 1:179Carcinogens

benzene, 1:102carbon tetrachloride, 1:192

chloroform, 1:214dichlorodiphenyltrichloroethane (DDT),

1:283–287ethylene oxide, 2:320formaldehyde, 2:327gamma-1,2,3,4,5,6-hexachlorocyclohexane,

2:335isoprene, 2:384methyl-t-butyl-ether, 2:462polyvinyl chloride, 3:619saccharin, 3:691styrene, 3:805triclocarban, 3:861triclosan, 3:865trinitrotoluene, 1:18

Carotenoids, 1:109–113Carothers, Wallace, 2:519Carson, Rachel, 1:284Cartier, Jacques, 1:95Cavendish, Henry, 2:494Caventou, Joseph Bienaime, 1:137, 219Celluloid, 1:202–203Cellulose, 1:195-199, 196 (ill.)Cellulose nitrate, 1:201-205, 202 (ill.)Cellulose xanthate, 1:207-210Cement, 1:145, 162–163, 167–168Chain, Ernst, 2:536Chalk, 1:143Chemical intermediaries, 1:119, 121–122, 131Chemical manufacturing, chemicals used in

acetylene, 1:28benzene, 1:101carbon monoxide, 1:185cumene, 1:255–256ethylene, 2:309ethylene oxide, 2:317–318hydrogen chloride, 2:359methane, 2:446methyl alcohol, 2:451methyl mercaptan, 2:456propylene, 3:671sodium chloride, 3:737sulfur dioxide, 3:820toluene, 3:855

Chemical warfare, 1:5–7Chemiluminescence, 2:407Chevreul, Eugene, 1:223; 2:349

CHEMICAL COMPOUNDS lxxxi

Index

Chlorine, 2:358; 3:795, 3:786Chlorofluorocarbons (CFCs), 1:190–191, 277–281Chloroform, 1:211-215, 212 (ill.)Chlorophyll, 1:217-221, 218 (ill.)Chocolate, 1:138; 3:843–846Cholesterol, 1:223-227, 224 (ill.)Church, Austin, 3:724Cinnabar, 2:439Cinnamaldehyde, 1:229-232, 240 (ill.)Cinnamomum camphora, 1:171, 173Cinnamomum zeylanicum, 1:229Citric acid, 1:233-237, 234 (ill.)Cleaning products, chemicals in

ammonium hydroxide, 1:70denatonium benzoate, 1:274oxalic acid, 2:527sodium bicarbonate, 3:726sodium hydroxide, 3:755sodium hypochlorite, 3:761sodium perborate, 3:766–767sodium silicate, 3:780tribasic sodium phosphate, 3:771See also Soaps and detergents, chemicals in

Clinton Corn Processing Co., 2:330–331Clorox, 3:761Cloud seeding, 3:702–704Coal tar, 2:473–475Cocoa beans, 3:843–846Coffee, 1:137–141Cola drinks, 1:137–141Collagen, 1:239-242; 2:338Contact process, 3:827Coolants, 2:315Coover, Harry, 1:259–260Copper(I) oxide, 1:243-246, 244 (ill.)Copper(II) oxide, 1:247-250, 248 (ill.)Copper(II) sulfate, 1:251-254, 252 (ill.)Cotton, 1:195–198Cox enzymes, 1:12; 2:479–480Cracking process, 2:309, 382; 3:669–670Cream of tartar, 3:629–631Crede, Carl, 3:705Crest toothpaste, 3:800Cross, Charles Frederick, 1:196, 207Cross-Bevan-Beadle method, 1:208Crude oil, 2:548, 553–557Cruikshank, William, 1:184

Cumene, 1:101, 255-258, 256 (ill.)Currie, James, 1:235Cyanamide process, 1:58Cyanoacrylate, 1:259-263, 260 (ill.)Cyanocobalamin, 1:265-269, 266 (ill.)Cyclamates, 3:741–744Cyclohexane, 1:101

•DDaguerre, Louis Jacques Mande, 3:702Darby, William J., 2:322Davy, Edmund, 1:27Davy, Sir Humphry, 2:358, 513, 515Day, Harry G., 3:800DDT, 1:283–287de la Salle, Poulletier, 1:223de Lassone, Joseph Marie Francois, 1:184Dead-burning, 2:419–420Death penalty, 3:641Decaffeination, 1:139DEET, 2:469–471Deicers, 1:25; 3:721Deiman, J.R., 2:307Denatonium benzoate, 1:271-275, 272 (ill.)Dentistry, chemicals used in

cyanoacrylate, 1:261dibasic calcium phosphate, 1:157nitrous oxide, 2:514–515sodium fluoride, 3:748–749stannous fluoride, 3:799–802

Deodorizers, room, 1:90Diabetes, 2:346Diapers, disposable, 3:773–776Diazonium compounds, production of, 1:91Dibasic calcium phosphate, 1:155–159Dibasic sodium phosphate, 3:769–772Dichlorodifluoromethane, 1:277-281, 278 (ill.)Dichlorodiphenyltrichloroethane (DDT),

1:283-287, 284 (ill.)Diesel fuel, 2:555Dimethyl ketone, 1:289-291, 290 (ill.)Dow, Herbert Henry, 2:412Dow Chemical Co., 2:584; 3:598Dow process, 2:412Drain cleaners, 3:755

lxxxii CHEMICAL COMPOUNDS

Index

Dry cell batteries, 1:65Drying agents, 3:698Dumas, Jean Baptiste Andre, 1:211, 229, 289DuPont Chemical Corp., 1:277–278; 2:519;

3:603–604, 742Dwight, John, 3:724Dyes and pigments

2,4,6-trinitrotoluene in, 1:18aluminum potassium sulfate, 1:55copper(I) oxide, 1:244copper(II) oxide, 1:247–248iron(II) oxide, 2:367iron(III) oxide, 2:373mercury(II) oxide, 2:441See also Paint, chemicals in

Dynamite, 2:508

•E

Eastman Kodak, 1:259–260Eggs, preservation of, 3:781Ehlers-Danlos syndrome, 1:240Eijkman, Christiaan, 3:849Elvehjem, Conrad Arnold, 2:484Engel-Precht process, 3:634–635Environmental concerns

acid rain, 1:153, 149chlorofluorocarbons (CFCs), 1:190–191,

277–281dichlorodiphenyltrichloroethane (DDT),

1:283–287methyl-t-butyl ether, 2:461nitric oxide, 2:497–499nitrogen dioxide, 2:504–505ozone layer depletion, 1:190–191,

213–214, 279petroleum, 2:556phosphates, 2:568pollution control, 1:152–153polystyrene, 3:600polyvinyl chloride, 3:618–619sulfur dioxide, 3:822triclocarban, 3:862triclosan, 3:865

Epsom salts, 2:429–433Erlenmeyer, Emil, 1:229; 2:473

Esters, 1:259–263Ethane, 1:120–121Ethyl acetate, 1:293-295, 294 (ill.)Ethyl alcohol, 2:297-301, 298 (ill.)Ethylbenzene, 1:101; 2:303-306, 304 (ill.)Ethylene, 1:2; 2:307-311, 308 (ill.), 581–582;

3:666Ethylene glycol, 2:313-316, 314 (ill.), 318Ethylene oxide, 2:317-320, 318 (ill.)Eutrophication, 2:568Evans, Herbert McLean, 1:37–38Exhaust gases, treatment of, 1:148Explosives

acetylene, 1:29ammonium nitrate, 1:74–75cellulose nitrate, 1:204nitric acid, 1:60nitroglycerin, 2:507–510perchlorates, 2:542–543potassium nitrate, 3:656styrene, 3:805TNT, 1:15–18toluene, 3:855–856

•F

Fabricsbleaching, 3:760cotton, 1:195–198dyeing of, 1:55; 3:720flax, 1:195–198nylon, 2:519–523polypropylene, 2:589polyurethane fibers, 3:612rayon, 1:207–210stain and water resistance, 3:605–606

Fahlberg, Constantine, 3:689–690Faraday, Michael, 1:99Farben, I.G., 3:598Fats, artificial, 3:813–816Fawcett, Eric, 2:580FDA (Food and Drug Administration, U.S.),

1:260–261; 2:404; 2:404; 3:815Fermentation, 1:294; 2:298–301Fertilizer, chemicals in

ammonia, 1:59–60

CHEMICAL COMPOUNDS lxxxiii

Index

ammonium nitrate, 1:74; 2:495ammonium sulfate, 1:77–78monocalcium phosphate, 1:157phosphoric acid, 2:567potassium chloride, 3:641potassium sulfate, 3:660sulfuric acid, 3:827tricalcium phosphate, 1:158urea, 3:870

Film, photographic, 1:203–204Fingerprints, collection of, 1:262Fire extinguishers, 1:180; 3:622Firestone, 2:384Fireworks, 1:75; 2:542–543; 3:656Fischer, Emil, 1:138; 2:345Fischer, Hans, 1:219Fischer-Tropsch reactions, 1:185Fittig, Rudolf, 3:855Flammable Fabrics Act of 1953, 1:209Flavorings

amyl acetate, 1:85–86cinnamaldehyde, 1:231ethyl acetate, 1:293–295isoamyl acetate, 2:377–380salt and salt substitutes, 2:465–468; 3:641,

653, 735–739sugars, 2:329–332, 343–347; 3:807–811sweeteners, artificial, 2:349–352, 401–405;

3:689–693, 741–744vanillin, 3:873–876

Flax, 1:195–198Fleming, Alexander, 1:82; 2:535Florey, Howard, 2:536Flourens, Marie Jean-Pierre, 1:211Fluoridating agents, 3:644Fluoridation, water, 1:43Fluorides, dental, 3:747–751, 799–802Foams, 3:611–612Folate, 2:321–324Folic acid, 2:321-324, 322 (ill.)Folkers, Karl, 1:266–267; 3:674Food additives

acidification agents, 1:158; 3:641, 771buffering agents, 3:721colorings, 1:112cream of tartar, 3:630–631folic acid, 2:321–324

isoamyl acetate, 2:377–380jelling agents, 2:531–533lactic acid, 2:393lactose, 2:397–399leavening agents, 3:723, 726nutritional supplements, 1:158potassium bicarbonate, 3:621–622potassium bisulfate, 3:625–627preservatives, 1:107, 117, 133–135, 233–236;

3:786–787stimulants, 1:117, 137–141See also Flavorings; Vitamins

Food and Drug Administration, U.S. (FDA),1:260–261; 2:404; 3:815

Food packaging, 3:775Food production, 3:649Forensic science, 2:409Formaldehyde, 2:325-328, 326 (ill.)Fox, Daniel W., 2:577Free radicals, 1:38Freon, 1:214, 277–281Friedel, Charles, 2:349Frohlich, Theodore, 1:95Fructose, 2:329-332, 330 (ill.)Fruits, 2:531–532Fuels

additives, 2:450, 459–462, 515–516butane, 1:121ethyl alcohol, 2:299gasoline, 2:555industrial, 1:185methane, 2:445oil, 1:75; 2:555perchlorates, 2:542–543propane, 3:663–667

Fumigants, 1:252Fungicides, 1:117, 244Funk, Casimir, 2:483Fusion, 2:420–421

•GGamma-1,2,3,4,5,6-hexachlorocyclohexane,

2:333-336, 334 (ill.)Gasoline, 2:555Gatorade, 3:744

lxxxiv CHEMICAL COMPOUNDS

Index

Gay-Lussac, Louis-Joseph, 1:116G.D. Searle Co., 2:401–402, 2:404Geber. See Jabir ibn Hayyan (Geber)Gelatin, 2:337-341Gemstones, 1:50Gerhardt, Charles Frederic, 1:19, 32; 2:559Gibson, Reginald, 2:580Glacial acetic acid, 1:23–26Glass manufacturing, chemicals used in

boric acid, 1:117potassium carbonate, 3:636potassium fluoride, 3:645silicon dioxide, 3:698silver oxide, 3:711–712sodium carbonate, 3:731–732sodium tetraborate, 3:791

Glass substitutes, 2:584Glauber, Johann, 1:73, 75; 2:358, 493, 559; 3:659Glazes, 1:244; 3:716Glow sticks, 2:410Glucose, 2:343-347, 344 (ill.)Glycerol, 2:349-352, 350 (ill.)Goldeberger, Joseph, 2:484Gout, 2:394–395Green chemistry, 1:11Grignard, Victor, 2:592Grijins, Gerrit, 3:849Gum benzoin, 1:105Guncotton, 1:201–205Gunpowder, 3:656–657Guthrie, Frederick, 1:5Guthrie, Samuel, 1:211Gypsum, 1:165–168

•HHaber, Fritz, 1:58–59Haber-Bosch process, 1:58–59, 178Hall, Charles Martin, 1:50–51Hallwachs, Wilhelm, 1:245Hard-burning, 2:420–421Harris, S.A., 3:674Haworth, Sir Walter Norman, 1:95HDPE (high density polyethylene), 2:579, 2:582Heart attack, prevention and treatment,

1:33–34; 2:500, 510

Helmont, Jan Baptista van, 1:177; 2:497;3:825–826

Hematite, 2:371–373Hexachlorophene, 3:860Hexane, 2:353-356, 354 (ill.)High-density lipoproteins (HDL), 1:226High-fructose corn syrup, 2:330–331Hodgkin, Dorothy, 1:267Hoffman, Felix, 1:33Hofmann, August Wilhelm von, 2:325; 3:853Hogan, John, 2:580, 582, 588Holberg, Wilhelm, 1:116Holst, Alex, 1:95Hormones, plant, 2:307–308Hot springs, 1:115–118; 2:430–431Hula hoops, 2:581Human body

cholesterol, 1:225–227collagen, 1:239–241fetal development, 2:321–323hormones, 3:837–840lactic adid, 2:392–393nicotine, effects of, 2:489–490nitric oxide in, 2:499–500nitroglycerin, use of, 2:510salt and, 3:738–739sucrose, effects of, 3:811urea in, 3:867–870water in, 3:882See also Medicine and medical products;

VitaminsHyatt, John Wesley, 1:202–203Hydrocarbons, 2:553–554Hydrochloric acid, 2:357–361Hydrochlorofluorobarbons (HCFCs), 1:212–214Hydrogen chloride, 2:357-361, 358 (ill.)Hydrogen peroxide, 2:363-366, 364 (ill.); 3:765Hydroxyapatite, 1:157

•I

Ideda, Kikunae, 2:465Imperial Chemicals Industries (ICI), 2:580Industrial accidents, 1:75Insect repellants, 2:469–471Insecticides, 1:283–287; 2:335, 488–489

CHEMICAL COMPOUNDS lxxxv

Index

Iron(II) oxide, 2:367-369, 368 (ill.)Iron(III) oxide, 2:371-375, 372 (ill.)Isler, Otto, 3:679Isoamyl acetate, 2:377-380, 378 (ill.)Isoprene, 2:381-385, 382 (ill.)Isopropyl alcohol, 2:387-389, 388 (ill.)

•J

Jabir ibn Hayyan (Geber), 1:23, 234–235Jams and jellies, 2:532–533JELL-O, 2:337–338Joiner, Fred, 1:259–260

•K

Kaminsky, Walter, 2:581–582Karrer, Paul, 1:38, 110; 3:678, 683Kekule, Friedrich August, 1:99–100, 102; 2:326Kerosene, 2:555–556Kidd, John, 2:473Kidney stones, 1:157King, Charles Glen, 1:95Kipping, Frederic Stanley, 2:592Kirchhof, Gottlieb Sigismund Constantine,

2:343Klate, Friedrich Heinrich August, 3:616Knox Gelatin, 2:337–338Krazy Glue, 1:259–263Krebs, Sir Hans Adolf, 1:234Krumbhaar, E.B., 1:7Krumbhaar, H.D., 1:7Kuhn, Richard, 3:674, 679, 683

•L

L-aspartyl-L-phenylalanine methyl ester,2:401-405, 402 (ill.)

Lactic acid, 2:391-395, 392 (ill.)Lactose, 2:397-400, 398 (ill.)Laughing gas, 2:513–517Lauwerenurgh, A., 2:307LDPE (low density polyethylene), 2:579, 582

Lead chamber process, 3:826Leavening agents, 3:723, 726Lebedev, Sergei, 1:1–2Leblanc, Nicolas, 2:358; 3:730–731Leroux, Henri, 1:32Lethal injections, 3:641Levenstein process, 1:6Libavius, Andreas, 1:79Liebig, Justus von, 1:289Light-burning, 2:420–421Lignin, 3:874–876Lime, 1:151–155Limestone, 1:144Lind, James, 1:95Liniments, 1:173Liquid Bandage, 1:261Liquid paraffin, 2:548Liquid petroleum gas (LPG), 1:121LoSalt, 3:641Low-density lipoproteins (LDL), 1:226Lucite, 2:584Luminol, 2:407-410, 408 (ill.)Lye, 3:753–757

•MMacfarlan Smith Corp., 1:272Magnesium chloride, 2:411-414, 412 (ill.)Magnesium hydroxide, 2:415-417, 416 (ill.)Magnesium metal, production of, 2:412Magnesium oxide, 2:419-422, 420 (ill.)Magnesium silicate hydroxide,

2:423-427, 424 (ill.)Magnesium sulfate, 2:429-433, 430 (ill.)Malaria, 1:283–286Marggraf, Andreas Sigismund, 2:343Marlex, 2:588Mattson, Fred, 3:813Maumee Chemical Co., 3:691Maynard, J. P., 1:204McKay, Frederick S., 3:801Medicine and medical products

analgesics, 1:9–13, 19–22, 31–34, 173antacids, 1:45–46, 144; 2:416–417;

3:621–622, 726antibiotics, 1:81–84; 2:535–538

lxxxvi CHEMICAL COMPOUNDS

Index

antiseptics, 1:117, 173, 261; 2:365; 3:652,859–865

aspirin, 1:31–34astringents, 3:834caffeine, 1:137–141cough and sinus treatments, 2:437, 562Epsom salts, 2:431hormones and hormone treatments, 2:543;

3:837–840laxatives, 2:550liniments, 1:173nitroglycerin, 2:500, 510NSAIDs, 2:477–480polyvinyl chloride in, 3:618silver nitrate, 3:707–708skin treatments, 2:437–438, 548–549, 562SSKI, 3:652theobromine, 3:845–846vasodilators, 1:90wound sealants, 1:260–261See also Dentistry, chemicals used in

Melsens, Louise, 2:487Menard, Louis-Phillippe, 1:204Menthol, 2:435-438, 436 (ill.)Mercury metal, 2:441Mercury(II) sulfide, 2:439-442, 440 (ill.)Metals, refining, 1:186Methane, 1:120–121; 2:443-447, 444 (ill.)Methanol, 1:272; 2:449–453Methyl alcohol, 2:449-453, 450 (ill.)Methyl mercaptan, 2:455-458, 456 (ill.)Methyl-t-butyl ether, 2:450, 459-463, 460 (ill.)Methylxanthines, 1:138MFP (Sodium monofluorophosphate), 3:801Midgley, Thomas, 1:278, 280Military dynamite, 1:17Milk, 2:397–399Milk of Magnesia, 2:415–417Miller, A. K., 1:1Mineral oil, 2:548Minerals (nutritional), 1:143–146, 155–159Minot, George, 1:266Mitchell, Henry K., 2:322Mitscherlich, Eilhardt, 1:99Mohammad ibn Zakariya al-Razi, 3:825Mohs, Frederick, 1:51Molina, Mario, 1:190, 278

Monobasic calcium phosphate, 1:155–159Monobasic sodium phosphate, 3:769–772Monosodium glutamate (MSG), 2:465-468,

466 (ill.)Monsanto Corp., 1:24Montecatini, 2:588Montreal Protocol on Substances that Deplete

the Ozone Layer, 1:191, 214, 279Morse, Harmon Northrop, 1:19Mortar, 1:148Mothballs, 2:475Motrin, 1:9–10MTBE (methyl-tert-butyl ether), 2:450, 459–463Muhler, Joseph C., 3:799–800Muller, Paul Hermann, 1:283Mummification, 3:730Murphy, William, 1:266Murray, Sir James, 2:415Muscles, 2:392–393Muspratt, James, 3:853Mustard gas, 1:5–8

•Nn-butyl acetate, 1:125–126n-butyl mercaptan, 1:129–132Nail polish remover, 1:290Napalm, 2:475Naphthalene, 2:473-476, 474 (ill.)Naproxen, 2:477-481, 478 (ill.)Nascent oxygen, 2:365Natta, Giulio, 2:384, 588–589Natural gas, 1:119–120; 2:443–446; 3:663–665Neljubow, Dmitri N., 2:308Neutralizing agents, 1:148Niacin, 2:483-486, 484 (ill.)Nicot, Jean, 2:487Nicotine, 2:487-491, 488 (ill.)Nitrating agents, 2:505Nitric acid, 1:60, 73–74; 2:493-496, 494 (ill.)Nitric oxide, 2:497-501, 498 (ill.), 504Nitro, 2:515–516Nitrogen, 1:74, 78Nitrogen dioxide, 2:503-506, 504 (ill.)Nitroglycerin, 2:500, 507-511, 508 (ill.)Nitrous oxide, 2:513-517, 514 (ill.)

CHEMICAL COMPOUNDS lxxxvii

Index

N,N-diethyl-3-methylbenzamide (DEET),2:469-472, 470 (ill.)

Nobel, Alfred, 2:508–509NSAIDs (nonsteroidal anti-inflammatory

drugs), 1:11–12, 19–22; 2:477–481Nuisance dust, 1:50–51Nuprin, 1:11NutraSweet, 2:401–405Nylon 6 and nylon 66, 2:519-523, 520 (ill.)

•OObesity, 3:811Odors and odorants, 1:130–131, 173; 2:377–380,

455–456Oil of vitriol, 3:825–829Oklahoma City bombing, 1:75Olestra, 3:813–8161,3-Butadiene, 1:1-4, 2 (ill.)Ostwald, Wilhelm, 1:60; 2:494Oxalic acid, 2:525-529, 526 (ill.)Oxidizing agents, 2:505Ozone layer, 1:190–191, 279

•P

Paint, chemicals in, 1:145, 244; 3:886See also Dyes and pigments

Paint thinners, 1:256Paper manufacturing, chemicals used in

aluminum potassium sulfate, 1:55calcium carbonate, 1:145cellulose, 1:198hydrogen peroxide, 2:365sodium hydroxide, 3:755sodium silicate, 3:781sodium sulfite, 3:785–786sodium thiosulfate, 3:795

Parkes, Alexander, 1:202Pauling, Linus, 1:96Payen, Anselme, 1:196Pearl ash, 3:633–637Pechmann, Hans von, 2:580Pectin, 2:531-534Peligot, Eugene Melchior, 1:229

Pellagra, 2:483–485Pelletier, Pierre Joseph, 1:137–138, 219; 3:853Pelouze, Theophile-Jules, 2:349Penicillin, 1:81–83; 2:535-539, 536 (ill.)Pennies, 1:249Pentolite, 1:17Peppermint, 2:435–436Perchlorates, 2:541-545, 542 (ill.)Periclase, 2:419Pernicious anemia, 1:265–268Perrin, M.W., 2:580PET (polyethylene terephthalate), 2:315Petrolatum, 2:547-551Petroleum, 2:353–354, 473–475, 553-557;

3:663–665, 671Petroleum jelly, 2:547–551PFOA (perfluorooctanoic acid), 3:606–607Phenol, 2:559-563, 560 (ill.)Phenylketonuria, 2:404Phillips, Charles Henry, 2:415Phillips, Peregrine, 3:827Phillips Petroleum, 2:580, 588Phosgene, 1:191Phosphates, 2:568Phosphoric acid, 2:565-569, 566 (ill.); 3:827Photoelectric cells, 1:244–245Photography, 3:702, 706–707, 796Photosynthesis, 1:217–221; 2:345Pictet, A., 2:487Pigments. See Dyes and pigmentsPiria, Raffaele, 1:32Plants, 1:195–199, 217–221; 2:307–308, 310;

3:831, 833See also Photosynthesis

Plaster of Paris, 1:165–168Plastic surgery, 1:240Plastics manufacturing, chemicals used in,

1:107benzoic acid, 1:107ethylene, 2:309ethylene glycol, 2:325–327formaldehyde, 2:325–327nylon, 2:5211,3-butadiene, 1:3petroleum, 2:556poly(styrene-butadiene-styrene), 2:572–573sodium hydroxide, 3:755

lxxxviii CHEMICAL COMPOUNDS

Index

styrene, 3:804–805Plexiglas, 2:584, 2:585Plunkett, Roy J., 3:604PMMA (Polymethylmethacrylate), 2:583–586Poisoning, treatment of, 1:90Pollution. See Environmental concernsPolycarbonates, 2:575-578, 576 (ill.)Polyethylene, 2:579-582, 580 (ill.)Polymethylmethacrylate (PMMA), 2:583-586,

584 (ill.)Polypropylene, 2:587-590, 588 (ill.); 3:669, 671Polysiloxane, 2:591-596, 592 (ill.)Polystyrene, 3:597-601, 598 (ill.), 804Poly(styrene-butadiene-styrene), 2:571-574,

572 (ill.)Polytetrafluoroethylene, 3:603-607, 604 (ill.)Polyurethane, 3:609-613, 610 (ill.)Polyvinyl acetates, 1:107Polyvinyl chloride, 3:615-619, 616 (ill.)Poppers, 1:91Portland cement, 1:162–163, 167–168Potash, 3:633–637Potash, caustic, 3:647–650Potassium benzoate, 1:107Potassium bicarbonate, 3:621-623, 622 (ill.)Potassium bisulfate, 3:625-627, 626 (ill.)Potassium bitartrate, 3:629-631, 630 (ill.)Potassium carbonate, 3:633-637, 634 (ill.)Potassium chloride, 3:639-642, 640 (ill.)Potassium compounds, production of, 3:648Potassium fluoride, 3:643-645, 644 (ill.)Potassium hydroxide, 3:647-650, 648 (ill.)Potassium iodide, 3:651-654, 652 (ill.)Potassium nitrate, 3:655-658, 656 (ill.)Potassium perchlorate, 2:541–543Potassium sulfate, 3:659-662, 660 (ill.)Preservatives, food

benzoic acid, role in, 1:107BHA and BHT, 1:134–135boric acid, 1:117citric acid, 1:233–236sodium sulfite, 3:786–787

Priestley, Joseph, 1:57, 178, 184; 2:358, 513;3:821

Procter & Gamble, 3:813–815Propane, 1:120–121; 3:663-667, 664 (ill.)Propellants, 1:122

Propylene, 3:666, 669-672, 670 (ill.)Provitamins, 1:110PVAs, 1:107PVC (polyvinyl chloride), 3:615–619Pyrex glass, 3:791Pyridoxine, 3:673-676, 674 (ill.)

•QQuicklime, 1:153

•RRadiation exposure, 3:652–653Raschig, Friedrich, 2:561Rayon, 1:207–210Recreational drugs

amyl nitrite, 1:89–82butane, 1:121hexane, 2:355nicotine, 2:489–490nitrous oxide, 2:514, 2:516

Red mercury(II) sulfide, 2:439–442Refrigerants, 1:180, 277–281Regnault, Henri Victor, 1:189Reichstein, Tadeusz, 1:95–96Reimer-Tiemann reaction, 3:875Remsen, Ira, 3:689–690Repe, Walter, 1:28Retinol, 3:677-681, 678 (ill.)Riboflavin, 3:683-687, 684 (ill.)Ritthausen, Karl Heinrich, 2:465Roche method, 1:111Rochow, E.G., 2:593Roebuck, John, 3:826Rohm, Otto, 2:583Rohm and Haas, 2:583, 2:585Rotschy, A., 2:487Rouelle, Hilaire Marin, 3:867Rowland, F. Sherwood, 1:190, 278Rubber, synthetic

isoprene, 2:383–3841,3-butadiene, 1:1–4Poly(styrene-butadiene-styrene), 2:571–574polystyrene used in, 3:598

CHEMICAL COMPOUNDS lxxxix

Index

polyurethane, 3:609–613Rufen, 1:9–10Rum, 3:810Runge, Friedlieb Ferdinand, 2:559Rust, 2:371

•S

Saccharin, 3:689-693, 690 (ill.)Sachs, Julius von, 1:219Sal ammoniac, 1:63–64Sal soda, 3:729–733Salt and salt substitutes, 2:465–468; 3:641, 653,

735–739Saltpeter, 3:655–658Saponification, 2:349–350SBS rubber, 2:571–574Schaefer, Vincent, 3:702–703Scheele, Karl Wilhelm, 1:235; 2:349, 392, 525;

3:629, 760Schlatter, James M., 2:401–402Schnell, Hermann, 2:576Schonbein, Christian Friedrich, 1:201Scrubbers, 1:153Scurvy, 1:93–95, 240Sea water, 3:639–640, 736sec-butyl acetate, 1:125–127sec-butyl mercaptan, 1:129–132Semiconductors, 1:247–250Semon, Waldo Lonsbury, 3:616–617Silica gel, 3:696–697Silicon dioxide, 3:695-700, 696 (ill.)Silicones, 2:591–596Silver iodide, 3:701-704, 702 (ill.)Silver nitrate, 3:705-709, 706 (ill.)Silver oxide, 3:711-713, 712 (ill.)Silver(I) sulfide, 3:715-717, 716 (ill.)Simon, Eduard, 3:597Simpson, Sir James Young, 1:211Sinn, Hansjorg, 2:581, 582Skin treatments

petroleum jelly, 2:548–549phenol, 2:562sunscreens, 3:886talc, 2:425tretinoin, 3:680

Skunk spray, 1:130–131Smokeless gunpowder, 1:204Soaps and detergents, chemicals in

phosphates, 2:568potassium hydroxide, 3:648sodium hydroxide, 3:756sodium tetraborate, 3:791–792triclocarban, 3:861triclosan, 3:864See also Cleaning products, chemicals in

Soapstone, 2:423–427Sobrero, Ascanio, 2:507Soda ash, 3:729–733Sodium acetate, 3:719-722, 720 (ill.)Sodium benzoate, 1:107Sodium bicarbonate, 3:723-727, 724 (ill.)Sodium carbonate, 3:729-733, 730 (ill.)Sodium chloride, 3:735-739, 736 (ill.)Sodium cyclamate, 3:741-745, 742 (ill.)Sodium fluoride, 3:747-751, 748 (ill.)Sodium hydroxide, 3:648, 753-757, 754 (ill.)Sodium hypochlorite, 3:759-763, 760 (ill.)Sodium perborate, 3:765-768, 766 (ill.)Sodium percarbonate, 3:767Sodium perchlorate, 2:541–543Sodium phosphate, 3:769-772, 770 (ill.)Sodium polyacrylate, 3:773-777, 774 (ill.)Sodium silicate, 3:779-783, 780 (ill.)Sodium sulfite, 3:785-787, 786 (ill.)Sodium tetraborate, 3:789-792, 790 (ill.)Sodium thiosulfate, 3:795-798, 796 (ill.)Soil additives

calcium hydroxide, 1:144, 148calcium sulfate, 1:167copper(II) sulfate, 1:252gamma-1,2,3,4,5,6-hexachlorocyclohexane,

2:335potash, 3:635See also Fertilizer, chemicals in

Solvay, Ernest, 1:64; 3:725, 731Solvents

butyl acetate, 1:126butyl mercaptan, 1:131dimethyl ketone, 1:290ethyl acetate, 1:293–294hexane, 2:353–354isopropyl alcohol, 2:388

xc CHEMICAL COMPOUNDS

Index

Soubeiran, Eugene, 1:211Specht, Walter, 2:407Stahl, Georg Ernst, 1:23Stalagmites and stalactites, 1:143, 145Standard Oil Co., 2:387Stannous fluoride, 3:799-802, 800 (ill.)Stannous hexafluorozirconate, 3:801Steam cracking, 1:2Steel production, 1:152Stockings, nylon, 2:522Stroke, protection against, 1:33–34Styrene, 2:303–304; 3:803-806, 804 (ill.)Styrofoam, 3:599Sucaryl, 3:743Sucrose, 2:329, 2:331; 3:807-811, 808 (ill.)Sucrose polyester, 3:813-817, 814 (ill.)Sugars

fructose, 2:329–332glucose, 2:343–347high-fructose corn syrup, 2:330–331sucrose, 2:329, 331; 3:807–811

Sulfur dioxide, 3:819-823, 820 (ill.)Sulfuric acid, 3:825-829, 826 (ill.)Sunscreens, 3:886Super Glue, 1:259–263, 261–262Supercritical carbon dioxide, 1:139, 179Sveda, Michael, 3:741Swallow, J.C., 2:580Sweeteners, artificial

glycerol, 2:349–352L-aspartyl-L-phenylalanine methyl ester,

2:401–405saccharin, 3:689–693sodium cyclamate, 3:741–744sucrose, 3:807–811

Szent-Gyorgi, Albert, 1:95; 3:673

•T

Tachenius, Otto, 3:659Takaki, Kanehiro, 3:849Talbot, William Henry Fox, 3:706Talc, 2:423–427Tannic acid, 3:831-835, 832 (ill.)Tanning (hides), 3:831–834Tarnish, 3:715, 717

Tastes, bitter, 1:271–274Tea, 1:137–141Teflon, 3:603–607Terpenes, 2:381–385tert-butyl acetate, 1:125–127tert-butyl mercaptan, 1:129–132Testosterone, 3:837-841, 838 (ill.)T&H Smith, 1:271Thenard, Louis Jacques, 1:116; 2:363Theobromine, 1:138–139; 3:843-846, 844 (ill.)Thiamine, 3:847-851, 848 (ill.)Thiele, Johannes, 1:101Thyroid gland, 3:652–653Tilden, Sir William Augustus, 2:384TNT, 1:15–18; 3:855–856Tobacco, 2:487–491Tocopherols, 1:37–40Tofu, 2:413Tollens, B.C.G., 3:855Toluene, 1:105–107; 3:853-857, 854 (ill.)Tooth decay, 3:748–749, 799–802, 811Torches, 1:27–29Torpex, 1:17Tournefort, Joseph, 1:64Tribasic calcium phosphate, 1:155–159Tribasic sodium phosphate, 3:769–772Triclocarban, 3:859-862, 860 (ill.)Triclosan, 3:863-866, 864 (ill.)Troostwyk, A. Paets van, 2:307Tschunkur, Eduard, 2:572TSP, 3:771Tsvett, Mikhail, 1:219Twenty-Mule-Team Borax, 3:791–7922-(4-Isobutylphenyl)-propionic acid, 1:9-13,

10 (ill.)2,4,6-Trinitrotoluene, 1:15-18, 16 (ill.)2,2-Dichorodiethyl sulfide, 1:5-8, 6 (ill.)Tylenol, 1:21

•UUmetaro, Suzuki, 3:847Upjohn Co., 1:10–11Urea, 3:867-871, 868 (ill.)

CHEMICAL COMPOUNDS xci

Index

•VVaccines, 1:47Vanillin, 3:873-877, 874 (ill.)Vaseline, 2:547–549Vasodilators, 1:89–90Vermillion, 2:440Vicks VapoRub, 1:173; 2:437–438Vinegar, 1:23–26Viscose Corp. of America, 1:208Vision, 3:679Vitamins

alpha-tocopherol (E), 1:37–40ascorbic acid (C), 1:93–97beta-carotene, 1:109–113; 3:678, 3:680cyanocobalamin (B12), 1:265–268folic acid (B9), 2:321–324niacin (B3), 2:483–486pyridoxine (B6), 3:673–676retinol (A), 3:677–681riboflavin (B2), 3:683–687thiamine (B1), 3:822, 847–851See also Minerals (nutritional)

Volpenhein, Robert, 3:813Vonnegut, Bernard, 3:703

•WWackenroder, Heinrich Wilhelm

Ferdinand, 1:110Waldie, David, 1:211Warning odors, 1:87Washing soda, 3:729–733Water, 3:879-884, 880 (ill.)Water treatment

aluminum potassium sulfate, 1:55

ammonium sulfate, 1:78fluoride, 1:43; 3:748–749sodium sulfite in, 3:786softeners, 3:737

Wedgwood, Thomas, 3:706Wehmer, Carl, 1:235Wells, Horace, 2:514Whipple, George Hoyt, 1:266Whitehall Laboratories, 1:11Wiegleb, Johann Christian, 2:525Wieland, Heinrich Otto, 1:224–225Wilbrand, Joseph, 1:15Williams, Robert R., 3:849–850Willow bark, 1:31–32Wills, Lucy, 2:321Winhaus, Adolf, 1:224–225Wislicenus, Johannes, 2:392Wohler, Friedrich, 1:27; 2:525; 3:867Wood alcohol, 2:449–453Wood preservatives, 1:248, 252Woodward, Robert Burns, 1:219, 225, 267Wounds, sealing of, 1:260–261Wulff process, 1:28Wurtz, Charles Adolphe, 2:313, 317

•X

Xylene, 3:855

•Z

Zeidler, Othmar, 1:283Zeolites, 1:257Ziegler, Karl, 2:384, 580, 2:582, 588–589Zinc oxide, 3:885-888, 886 (ill.)

xcii CHEMICAL COMPOUNDS

Index

Documents

Chemical compounds