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Spring 2014

Lecture 11:Organic compounds II : Functional groups and the molecules of life

Course lecturer Jasmin Šutković6th May 2014

Contents International University of Sarajevo

1. Arenes2. Alcohols3. Ethers4. Aldehydes5. Ketones6. Carboxylic acid7. Molecules of life

• Proteins • Carbohydrates • Lipids• Nucleic acids

Arenes – cycle hydrocarbons

Most arenes with a single six-membered ring are volatile liquids

Benzene, C6H6, is the simplest aromatic hydrocarbon, and it was the first one recognized. 

Arenes are Compounds containing both aliphatic and aromatic parts.

Alkyl-benzenesAlkenyl-benzenesAlkynyl-benzenes

Etc….

Volatility ?

Volatility is a measure of a substance's vapor pressure and it's tendency to vaporize.

Polycyclic aromatic hydrocarbons are lipophilic, meaning they mix more easily with oil than water

Example of Poly-aromatic hydrocarbons is Hexa-peri-hexabenzocoronene- one of the most widespread organic pollutants.

Its toxic to humans !

Aromatic VS. Aliphatic

In organic chemistry, compounds composed of carbon and hydrogen are divided into two classes: 

aromatic compounds, which contain benzene or similarly aromatic rings of atoms- cyclic

aliphatic compounds  which do not contain those rings.

Alkyl-benzenes, nomenclature:Special names

CH3 CH3CH3

CH3

CH3

CH3

CH3

toluene o-xylene m-xylene p-xylene

others named as “alkyl benzenes”:

CHH3C CH3 CH2

H2CCH3

H2C

CHCH3

CH3

isopropylbenzene n-propylbenzene isobutylbenzene

CH2

CH2

CH3

CH3

o-diethylbenzene n-butylbenzene

Alcohols

Alcohols are characterized by the presence of an - OH group generally in a bent shape, like that of water.

Due to the presence of an -OH group, alcohols can  have a hydrogen bond. This leads to higher boiling points compared to their parent alkanes.

Alcohols are polar in nature. This is attributed to the difference in electronegativity between the carbon and the oxygen atoms.

Are classified as primary, secondary, or tertiary, depending on whether the –OH group is bonded to a primary, secondary, or tertiary carbon

Ethers

Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'.

Good solvents for organic compounds Unreactive because they lack the –OH unit

Aldehydes

An ALDEHYDE is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center (a carbon double bonded to oxygen) bonded to hydrogen and an R group, which is any generic alkyl or side chain.

Contain the carbonyl functional group Prepared by the oxidation of alcohols

Formalaldehyde

Simplest aldehyde  Also called by its systematic

name methanal. Used as :

Disinfectant  Fixative for human tissues Formaldehyde-based materials are key to the manufacture of

automobiles, and used to make components for the transmission, electrical system, engine block, door panels, axles and brake shoes.

Ketones

A KETONE  is an organic compound with the structure RC(=O)R', where the  carbonyl group (C=O) is bonded to two other carbon atoms.

Many ketones are known and many are of great importance in industry and in biology. Examples include many sugars (ketoses) and the industrial solvent acetone.

Acetone

Simplest ketone It is what's found in nail polish remover

and paint removers

Urea – another example of ketone

Ketoses

Have at least one KETONE group.

Carboxylic Acids

Compounds that contain the carboxyl functional group are weakly acidic because of delocalization of the electrons, which causes them to lose a proton and form the carboxylate anion

Carboxylic acids are ACIDS because they are proton (H+) donors.

Carboxylic acids….They are the most common type of organic acid. Among the simplest examples are formic acid H-COOH, which occurs in ants.

Another example COOH compounds …

acetic acid CH3-COOH, which gives vinegar its sour taste.

Carboxylic acids are used in the production of polymers, pharmaceuticals, solvents, and food additives.

Carboxylic Acid Derivatives

EstersEsters are chemical compounds consisting of a carbonyl adjacent to an ether linkage

Esters are usually derived from an inorganic acid or organic acid in which at least one -OH (hydroxyl) group is replaced by an -O-alkyl (alkoxy) group, and most commonly from carboxylic acids and alcohols.

Esters are responsible for the aroma of many fruits, including apples, durians, pears, bananas, pineapples, and strawberries. Several billion kilograms of polyesters are produced industrially annually.

The Molecules of Life

• All the functional groups described are found in the organic molecules that constitute and maintain every living organism on

• The most abundant substances found in living systems belong to four major classes:

1. Proteins 2. Carbohydrates

3. Lipids 4. Nucleic acids

• Proteins are biologically active polymers formed from amino acids linked together by amide bonds; in addition to an amine group and a carboxylic acid group, each amino acid contains a characteristic R group

The nature of the R group determines the particular chemical properties of each amino acid !!!

• Some proteins are enzymes that catalyze biological reactions

Proteins

• Carbohydrates are the most abundant of the organic compounds found in nature; they constitute a substantial portion of food that is consumed to provide energy needed to support life

• Carbohydrates are polyhydroxy aldehydes or polyhydroxy ketones

– The simplest carbohydrates consist of unbranched chains of three to eight carbon atoms; one carbon is a carbonyl carbon and the others are bonded to hydroxyl groups

Carbohydrates

Carbohydrates

Carbohydrates are classified according to the number of single saccharide units they contain

1. The simplest are monosaccharides – Contain several chiral carbons and exist in several

isomeric forms – An example is glucose

2. A disaccharide consists of two linked monosaccharide units and an example is sucrose

3. A trisaccharide is three linked monosaccharide units

4. Polysaccharides contain more than 10 monosaccharide units

Carbohydrates

– Characterized by their insolubility in water

– Form a family of compounds that includes fats, waxes, vitamins (A,D,E and K) and steroids

– Fatty acids are the simplest lipids and have a long hydrocarbon chain that ends with a carboxylic acid functional group

1. Saturated fatty acids—the hydrocarbon chains contain only C–C single bonds that stack in a regular array

2. Unsaturated fatty acids—have a single double bond in the hydrocarbon chain (monounsaturated) or more than one double

bond (polyunsaturated); double bonds give fatty acid chains a kinked structure, which prevents the molecules from

packing tightly

Lipids

The main biological functions of lipids include storing energy, signaling, and acting as structural components of cell membranes

• Nucleic acids are the basic structural components of DNA and RNA, the biochemical substances found in the nuclei of cells that transmit the information needed to direct cellular growth and reproduction !!

• Structures are derived from nitrogen-containing cyclic compounds called pyrimidines and purines and those are Guanine, Cytosine, Thymine and Adenine !

• When a pyrimidine or purine is linked to a sugar by a bond called a glycosidic bond, a nucleoside is formed; if we add a phosphoric acid group to the sugar of nucleoside then we get a nucleotide !

Nucleic Acids

• Nucleotides link to form a polymeric chain (many nucletides) that consists of alternating sugar and phosphate groups and so create the backbone of Deoxyribonucleic acid- DNA and Ribonucleic acid - RNA

• The function of DNA is to preserve genetic information, and RNA translates the genetic information in DNA and carries that information to cellular sites where proteins are synthesized !

Nucleic Acids

DNA and RNA

Readings

Chapter 24 (second part) Book pages 1648 - 1673

One more lecture to go …