Amines, amino acids, and polymers

Question 1

What is an aliphatic amine:

Answer 1

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

Question 2

What is an aromatic amine:

Answer 2

The nitrogen in the attached to an aromatic ring.

Question 3

What is a primary amine?

Answer 3

The nitrogen is attached to a single carbon

Question 4

What is a secondary amine?

Answer 4

The nitrogen is attached to two carbons.

Question 5

What is a tertiary amine:

Answer 5

The nitrogen is attached to 3 carbons.

Question 6

How do you name an amine with 2 or more groups attached to a nitrogen atom?

Answer 6

Compound is named as an N-substituted derivative of the larger group. e.g CH3NHCH2CH2CH3 is N-methylpropylamine

Question 7

Why can amines behave as bases?

Answer 7

The lone pair of electrons on the nitrogen can accept a proton. To form a dative covalent bond.

Question 8

Amines to form salt:

Answer 8

The amine reacts with acid to form a single salt, made-up of the carbocation (proton accepted by nitrogen) and negatively charged ion in of the acid.

Question 9

Formation of primary amine:

Answer 9

• Nucleophilic substitution between Ammonia and haloalkane to form ammonium salt
• Ammonium salt + base -> Primary amine + salt + water

Question 10

Conditions for the formation of a primary amine:

Answer 10

Ethanol solvent - to prevent further substitution of haloalkane by water to produce alcohols
Excess Ammonia used - To reduce further substitution of the amine group to form secondary/tertiary amines.

Question 11

Why is the reaction for the formation of a primary amine unsuitable for the extraction of a pure primary amine?

Answer 11

The primary amine can undergo further substitutions to form secondary/tertiary amines
There is a mixture of products.

Question 12

Formation of secondary/tertiary amines:

Answer 12

Further substitutions:
Primary/Secondary amine + haloalkane -> Di/Tri-ammonium salt
Salt reacts with base to form further substituted amine.

Question 13

Preparation Aromatic Amine:

Answer 13

Nitrobenzene is heated under reflux with tin and concentrated HCl to form ammonium salt and phenylammonium chloride. Phenylammonium chloride is reacted with excess NaOH to produce the aromatic amine, phenylamine.

Question 14

What is the purpose of tin and HCL in the preparation of aromatic amines?

Answer 14

To act as a reducing agent.

Question 15

What is an a-amino acid?

Answer 15

The amine and carboxylic acid groups are attached to the same carbon.

Question 16

What is the general formula of an a-amino acid:

Answer 16

RCH(NH2)COOH

Question 17

Reaction of amino acid with acid:

Answer 17

Amino acid + HCl -> Ammonium salt

Question 18

The carboxylic acid group (on an amino acid) + alkali:

Answer 18

Forms amine salt + H2O

Question 19

Polymerisation between carboxylic acid group + alcohols:

Answer 19

Forms ester + H2O - Conc. H2SO4 catalyst

Question 20

What is the purpose of Sulfuric acid in the acidic esterification of an amino acid?

Answer 20

To protonate the basic amine group of the ester.

Question 21

What is meant by amino acids being amphoteric?

Answer 21

The compound can work as both an acid and a base.

Question 22

What are amides?

Answer 22

They are the product of the reactions of acyl chlorides or carboxylic acids with ammonia or amines.

Question 23

What is a chiral centre:

Answer 23

A carbon atom attached to four different atoms or groups or atoms.

Question 24

What is the alternate term for optical isomers:

Answer 24

Ecantoisomers.

Question 25

What are the two different combinations of monomers for the formation of polyesters by condensation?

Answer 25

• Repeating single monomer containing both a carboxylic acid and alcohol group.
• Two alternating monomers, one with 2 (di)carboxylic acid groups and one with 2 alcohol groups (diol).

Question 26

What bonds are formed during the formation of a polyester?

Answer 26

Ester linkages

Question 27

What are the two different combinations of monomers for the formation of polyamides by condensation?

Answer 27

• Repeating monomer with both an amine and carboxylic acid or acyl chloride group.
• Two alternating monomers - one a diamine and the other a dicarboxylic acid or diacyl chloride.

Question 28

What is the name of a polyamide made up of amino acids?

Answer 28

Polypeptide.

Question 29

What are the two ways to hydrolyse condensation polymers?

Answer 29

Acid hydrolysis

Alkali Hydrolysis

Question 30

Products of the hydrolysis of polyamides?

Answer 30

Acid - Ammonium Carbon chain + carboxylic acid

Alkali - Amine carbon chain + Carboxylate salt

Question 31

How do you name an amide?

Answer 31

If Amide group joined to the single carbon chain it’s named e.g “propanamide”.
If the amide group is joined to 2 or more groups the compound is named with the prefix N, repeated for the number of side chains followed by the branches and carbon chain with the C=O bond. e.g (“N,N - dimethylpropanamide)

Question 32

How do alkenes form polymers

Answer 32

addition polymerisation

Question 33

what is condensation polymerisation

Answer 33

the joining of monomers with the loss of a small molecule, usually water or hydrogen chloride

Question 34

which functional groups does one monomer need to form a polyester

Answer 34

hydroxyl (OH) and carboxyl (COOH)

Question 35

what are polyamides

Answer 35

condensation polymers formed when monomers are joined together by amide linkages in a long chain to form the polymer.

Question 36

What is needed to hydrolyse condensation polymers

Answer 36

hot aqueous alkali (e.g. NaOH) or hot aqueous acid (e.g. HCl)