Pre DP Chemistry 2 Organic Chemistry - Mattliden · to boiling point) by fractional distillation....

Teacher: Annika Nybergannika.nyberg@mattliden.fi

Pre DP Chemistry 2 Organic Chemistry

Content1. Introduction

2. Hydrocarbons

3. Functional groups

4. Alcohols and phenols

5. Aldehydes

6. Ketones

7. Carboxylic acids, Acid -base reactions

8. Esters

9. Amines

10. Fats, Proteins, Carbohydrates

11. Dilution of solutions

Revision

http://www.ck12.org/ngss/middle-school-physical-sciences%2Fmatter-and-its-interactions

Assessment

● Exam: 70 %

● Quiz1: 10 %

● Quiz2: 10%

● Project: 10%

● Quiz 11.2.15: Naming hydrocarbons

● TEST 27.3.2015

BBC News: Complex organic molecule found in interstellar space

● Science reporter Michael Eyre: ”Scientists have found the beginnings of life-bearing chemistry at the centre of the galaxy.”

https://www.youtube.com/watch?v=aqvTzhtT4S0

1. Introduction

1.1 Carbon is a unique element

● Carbon atoms can form long chains that are linked by single, double and/or triple bonds.

● Carbon and hydrogen are the basic building blocks in organic compounds.

● Other elements can be present in organic compounds as well, such as oxygen, nitrogen, phosphorus, halogens (F, Cl, Br, I) or sulfur.

1.2 Organic compounds

● Every living organism is made of organic compounds and the organic compounds are all around you:

- proteins (that make up your hair, skin and muscles)

- DNA (controls your genetic heritage)

- the food you eat

- the clothes you wear

- the medicines you take

Demo: sucrose + sulfuric acid

1.3 The carbon cycle

● http://www.youtube.com/watch?v=nzImo8kSXiU

https://www.youtube.com/watch?v=aLuSi_6Ol8M&list=PL8dPuuaLjXtPHzzYuWy6fYEaX9mQQ8oGr&index=47

1.4 Crude oil

● Crude oil was formed over millions of years ago when the remains of animals and plants were trapped under layers of rock.

● Crude oil is a complex mixture of many different organic compounds, mainly alkanes.

● In an oil refinery the alkanes are separated (according to boiling point) by fractional distillation.

● The various fractions, with different physical characteristics, are used in a wide variety of circumstances, mainly as fuels.

1.5 Refining

Pearson etext topic 10 fractional distillation of crude oil

2. Hydrocarbons

● A hydrocarbon is an organic compound that consists of ONLY carbon and hydrogen.

● The carbon atoms are bonded together to form the "backbone" to which the hydrogen atoms are bonded.

● There are at least 6 million different organic compounds, all with their own physical and chemical properties.

● In order to study all these organic compounds, they are categorized into ”families” according to their structures.

● Members of these families have similar chemical reactivities.

● Straight chain hydrocarbon:

● Branched hydrocarbons:

● Cyclic hydrocarbons:

2.1 Ways to describe organic compounds

● Empirical formula: The simplest whole number ratio of the atoms in a molecule. CH

2O

● Molecular formula: The actual number of atoms in a molecule. C

6H

12O

6

● Structural formula: How the atoms are bonded to each other in a molecule.

● Full structure

● Condensed structure

● Skeletal (line-bond) structure

● Molecular model

CH3CH

2CH

2CH

2CH

2CH

3

2.2 Isomers

● Compounds with the same molecular formula but with different structures.

● Draw the three different structures of C5H

12 and the five

different structures of C6H

14

C8H

18

C9H

20 has 35 isomeres C

20H

42 has 366 319 isomeres

2.3 Alkanes

● Saturated (= only single bonds between the carbons)

Reactivity

● Alkanes are stable under most conditions, because of strong C-C and C-H bonds and low polarity.

● Combustion:

General formula CnH

2n+2

Boiling point of alkanes

● The boiling points increases as the carbon chain gets longer.

2.4 Alkenes

● Unsaturated (double bond/bonds).

● The double bond reacts in addition reactions.

Addition reaction

Alkene test

● Alkenes readily undergo addition reactions, whereas alkanes will not.

Polyethene

2.5 Alkynes

● Unsaturated (triple bonds).

2.6 Aromatic Hydrocarbons

benzene

2.7 Halogenated hydrocarbons

Chloroform

● Chloroform has been used by criminals to knock out, their victims.

● Homework: Read chapter 6 (Cliff Notes) ppg. 53-64.

Prefix - Parent - Suffix

e.g. 3-methylhexane

Where are the substituents? How many carbons? What family?

2.8 Naming hydrocarbons

What is the name of the molecule?

The systematic name of an hydrocarbon is obtained using the following rules:

1. Determine the number of carbons in the longest continuous carbon chain. This chain is called the parent hydrocarbon.

Number of C parent

1 meth

2 eth

3 prop

4 but

5 pent

6 hex

7 hept

8 oct

9 non

10 dec

2. The functional group is described by a ending (= suffix) to the name.

● Single bond: -ane

● Double bond: -ene

● Triple bond: -yne

3. The name of any alkyl substituent (= the branches) is cited before the name of the parent hydrocarbon.

● Indicate the position with a number. ● Give the substituent as low a number as possible.

Alkyl group Name

-CH3

methyl

-CH2CH

3ethyl

-CH2CH

2CH

3propyl

-CH2CH

2CH

2CH

3butyl

-CH2CH

2CH

2CH

2CH

3pentyl

4. If more than one substituent is attached to the parent hydrocarbon, the chain is numbered in the direction that will result in the lowest possible number in the name of the compound.

5. If a compound contains two or more identical substitutes, the prefixes “di,” “tri,” and “tetra” are used.

2,3-dimethylbutane

3. Functional groups

● A functional group is the active group in an organic compound.

● It reacts easily and thereby determines the characteristics of the compound.

● All compounds that have the same functional group form their own homologous series.

● A molecule can have more than one functional group.

Ex. Identify the functional groups in the LSD molecule.

Ex. Identify and name the functional groups in the heroine molecule.

Ex. Identify the organic compound(s) that area) alcohols b) amines c) aldehydes.

Project about an organic compound/family of compounds

● In pairs

● Prepare a 10 min presentation

● Project presentations:

– 11.3.2015

– 13.3.2015

● ~10-20% of the course grade

● Name (trivial & systematic name)

● Structural formula, molecular formula, molar mass

● All functional groups named

● Melting point, boiling point

● Appearance

● Chemical properties and reactivity (reactions)

● Hazards/Safety

● History

● Production of the substance

● Biological properties

● Occurence in nature

● Usage

● Occurence in popular culture (litterature, movies)

● A short youtube about 2min.

4. Alcohols and Phenols

4.1 Alcohols

● contain one or more polar hydroxyl group:

● The more hydroxyl groups, the stronger the hydrogen bonds between the molecules → higher viscosity and higher boiling points.

4.2 Phenols

● When the hydroxylgroup is attached directly to a benzene ring, the group is called a phenyl hydroxyl group.

● These compounds are not classified as alcohols,but as phenols.

● Phenols are weak acids.

● Draw structures that meet the following descriptions:

a) Two isomers with the formula C4H

8O

2

C3H

6O

4.3 Naming

● Alcohols are also classified as primary, secondary or tertiary, depending on the location of the hydroxylgroup.

C-

● If there are two or more functional groups in a molecule, the order is:

carboxylic acid > ketone/aldehyde > alcohol > amine > halide

4.4 Combustion

● When an organic compound undergoes complete combustion, the products are always CO

2 and H

2O.

● Ex. Write the balanced equation for the combustion of ethanol

C2H

6O (l) +3O

2 (g) → 3H

2O (g) + 2CO

2 (g)

● What mass of glucose must be fermeted to give 5.oo kg of ethanol?

● Calculate the amount of ethanol in moles (nethanol

)

● Calculate the amount of glucose in moles (= ½ nethanol

)

● Calculate the mass of glucose.

4.5 Oxidation of alcohols

primary alcohol aldehyde carboxylic acid

secondary alcohol ketone

4.6 Mass percent

● Ex. Calculate the mass-% of sugar in a solution that contains 50 grams sugar in 210 grams of water.

4.7 Volume percent

Ex. Calculate the volume of pure ethanol in a bottle of wine (750 ml) with a 12 volume-% of ethanol.

Ex. Calculate the volume of pure acetic acid in a diluted vinegar solution with 10 percent of acetic acid by volume .

5. Aldehydes

Aldehydes from alcohols

MnO2

(bitter almond oil)

Formaldehyde: - TOXIC- a gas at room tempertures (bp. -19º C)- colorless and has a characteristic pungent, irritating odor- used for preservation of biological specimens

Vanillin Anisaldehyde

6. Ketones

Acetone: - colorless liquid- important solvent- used in nail polish removers and as paint thinner

7. Carboxylic Acids

ethanoic acid butanoic acid hexanoic acid

(vinegar) (sour butter) (dirty gym socks)

7.1 Condensation reaction

● Carboxylic acids react with alcohols to form esters:

7.2 Acid-base reactions

ethanoic acid oxalic acid

Acids

● An acid donates protons (H+) to a base that accepts protons in a chemical reaction.

● A base must have an extra nonbonded electron pair that it can share with the proton.

● An aqueous solution becomes acidic when an acid donates a proton to a water molecule, because an oxonium ion (H

3O+) is produced.

8. Esters

9. Amines

● Amines are derivatives of ammonia, where 1, 2 or 3 hydrogens have been displaced by carbon chains.

● Amines are therefore classified as primary, secondary or tertiary.

(Unpleasant odour from the body of dead

animals)

Ex. State whether the following amines are primary, secondary or tertiary.

Bases

● An aqueous solution becomes alkaline (basic) when a base acceptes a proton from a water molecule.

● A hydroxide ion (OH-) is produced:

The reaction of amines and water

● Amines are bases and react with water to produce hydroxide ions:

Neutralization

● A chemical reaction between an acid and a base to produce a salt and water:

9.1 The neutralization reaction of amines with acids

● The fishy odor of di- and trimethylamines dissapears if they are neutralized with citric acid or ethanoic acid.

The pH-scale

● For every billion of water molecules two are ionized:

8.1 Fats

● Fats and oils are large esters, as they form when glycerol and three fatty acids (= carboxylic acids with long carbon chains containing an even number of carbon atoms between 12 and 20) undergo condensation reaction:

● The three fatty acids need not be the same. A given fat or oil is usually a complex mixture of esters of different fatty acids.

● Example of a natural triglyceride with three different fatty acids. One fatty acids is saturated (blue highlighted), another contains one double bond within the carbon chain (green highlighted). The third fatty acid (a polyunsaturated fatty acid, highlighted in red) contains three double bonds within the carbon chain.

8.2 Saturated fats

● The fat is saturated if the fatty acids only have single carbon-carbon bonds in the chain.

● Animal fats are saturated fats and are solids in room temperature.

8.3 Unsaturated fats

● Vegetable fats are unsaturated fats as they consist of fatty acids with double/triple bonds.

● Vegetable fats are often liquids in room temperature, because of the double bonds in their structure. They cannot be tightly packed.

9.2 Amino acids

● Amino acids contain two functional groups: a basic amino group and an acidic carboxyl group.

9.3 Peptide bond

9.4 Proteins

● All proteins are made up of many amino acids linked together into a long chain.

● The sequence in which amino acids are bonded together determine only the primary protein structure.

● The large molecule then folds and bonds with other protein molecules to form the final protein.

Structure of proteins

● All proteins are made up of many amino acids linked together into a long chain (more than 50 amino acids) = polypeptides.

Primary structure: the number and sequence of the aminoacids in the polypeptide chain.

Secondary structure: The way in which the chain of amino acids folds itself due to intramolecular hydrogen bonding.

Tertiary structure: Interactions between the side-chains to give the protein its threedimensional shape.

Quaternary structure: Separate polypeptide chains that interact together to give a more complex structure.

Proteins occur in every living organism

● Keratine in skin and fingernails

● Spider web

● Enzymes

● Catalysts in the synthesis of DNA

9.5 Protein denaturation

● A small change in temperature or pH will disrupt the tertiary structure (the weak intermolecular bonds between the chains) and cause the protein to become denatured.

● The primary structure remains intact (the covalent bonds are not affected), but the protein unfolds from its well defined shape to a randomly shape.

10. Carbohydrates

● Carbohydrates are our main source of energy.

● The larger the molecule, the longer it takes for our bodies to break it down.

● Most of the simple carbohydrates taste sweet.

10.1 Monosaccharides

Glucose Fructose Galactose

● Monosacharides contain a carbonyl group (C=O) and at least two –OH groups

● Empirical formula: CH2O

Straight-chain and ring structural formulas

Common isomers of C6H12O6

10.2 Disaccharide

● Two monosaccharides, linked together.

● Sucrose (table sugar) is a disaccharide made up of one glucose molecule linked to one fructose molecule.

10.3 Polysaccharide

● Cellulose is a polysaccharide made up of several thousand glucose molecules linked together.

Every living organism contains carbohydrates:

● Sugar and starch in food

● Cellulose in wood, paper and cotton

● Carbohydrates are synthesized by green plants during photosynthesis:

11. Dilution of solutions

● Ex. If 25,0 ml of 0,56 M H2SO

4 is diluted to a volume of

125 ml, what is the molarity of the resulting solution?

● Ex. To what volume must 50,0 ml of 1,50 M HCl be diluted to produce 0,200 M HCl?

● Ex. How would you prepare 1,00 l of a 0,50 M solution of H

2SO

4 from concentrated (18 M) sulfuric acid?