MODULE 6: Amines, Amino Acids and Polymers

Question 1

Amine:

Answer 1

A compound in which one or more hydrogens in an ammonia molecule (NH3) have been replaced by a carbon chain/ring

Question 2

Aliphatic amine:

Answer 2

Nitrogen atom is bonded to at least one straight or branched carbon chain

Question 3

Aromatic amine:

Answer 3

Nitrogen atom is attached to an aromatic ring to form a phenylamine

Question 4

Primary amine:

Answer 4

Only one R-group attached to the nitrogen atom

Question 5

Secondary amine:

Answer 5

Two R-groups attached to the nitrogen atom

Question 6

Tertiary amine:

Answer 6

Three R-groups attached to the nitrogen atom

Question 7

Naming primary amines:

Answer 7

On carbon one it is named as ‘[prefix]amine’, the prefix being the chain before (ethyl, propyl). Any other carbon, the prefix ‘amino’ is used, with the number carbon it is on

Question 8

Naming secondary and tertiary amines:

Answer 8

When containing the same alkyl group, di and tri are used to show the number of alkyl groups attached to the nitrogen. When containing different alkyl groups, N-substituted variant is used, e.g. N-methyl, ethylamine

Question 9

Amine reaction with acids:

Answer 9

Amines act as a base to neutralise acids, and forms an ammonium ion (e.g. ethylammonium ion), which forms a salt

Question 10

Preparation of a primary amine:

Answer 10

• Ammonia is reacted with a haloalkane to form an ammonium ion
• The ammonium ion reacts with the haloalkane to form an ammonium salt
• Sodium hydroxide is used to remove the halogen from the ammonium salt, resulting in the amine, sodium halogen salt and water
• Excess alcohol is used to prevent formation of an alcohol instead of an amine
• Excess ammonia is used to prevent formation of a secondary or tertiary alcohol

Question 11

Preparation of secondary and tertiary amines:

Answer 11

SECONDARY: further substitution of a halide ion onto the lone pair of electrons on the nitrogen atom, to allow for the same reaction as a primary amine
TERTIARY: further reaction of a secondary amine

Question 12

Preparation of aromatic amines:

Answer 12

• Nitrobenzene is heated under reflux with tin and hydrochloric acid to form a phenylammonium salt, phenylammonium chloride
• Then reacted with excess sodium hydroxide to form a phenylamine and two moles of water

Question 13

Formula of an alpha amino acid:

Answer 13

RCH(NH2)COOH

Question 14

Reaction of the amine group of an amino acid:

Answer 14

The amine group is basic, so reutralises the acid to form an ammonium ion and negative ion from the previous acid

Question 15

Reaction of the carboxylic group of an amino acid:

Answer 15

Can react with alkalis to form carboxylate salts and alcohols to form esters

Question 16

Amide:

Answer 16

Reactions of acyl chlorides and carboxylic acids with ammonia and amines, for example:
CH3COCl + NH3 –> CH3CO(NH2) + HCl

Question 17

Primary amide:

Answer 17

One carbon bonded to the amide group

Question 18

Secondary amide:

Answer 18

Two carbons bonded to the amide group

Question 19

Tertiary amide:

Answer 19

Three carbons bonded to the amide group

Question 20

Chirality:

Answer 20

When optical isomerism occurs around a chiral center- a carbon in a molecule that is bonded to at least 4 different groups

Question 21

Name of optical isomers:

Answer 21

Enantiomers

Question 22

Chirality in amino acids:

Answer 22

All amino acids have chirality (except glycine)

Question 23

Addition polymerisation:

Answer 23

When alkenes form polymers

Question 24

Condensation polymerisation:

Answer 24

When a mole of water is formed from the formation of a polymer

Question 25

Examples of condensation polymers:

Answer 25

Polyesters and polyamides

Question 26

Formation of polyesters:

Answer 26

Can be formed from one monomer or two separate monomers:
One monomer being the 2 functional groups (carboxylic acid and alcohol at opposite ends)
Two monomers being 2 alcohols and 2 carboxylic acids

Question 27

Formation of polyesters

Answer 27

Can be formed from one monomer or two separate monomers:
One monomer being the 2 functional groups (carboxylic acid/acyl chloride and amine at opposite ends, aka an amino acid)
Two monomers being 2 amine and 2 carboxylic acids/acyl chloride

Question 28

Hydrolysis of condensation polymers:

Answer 28

Can be hydrolysed with hot aqueous acid or alkali