27) Amines, amino acids and proteins

Question 1

What are amines?

Answer 1

organic compounds, derived from ammonia, NH3, in which one or more hydrogen atoms have been replaced by a carbon chain or ring

Question 2

What is the suffix and prefix for primary amines?

Answer 2

suffix = -amine (NH2 at end)
prefix = amino- (NH2 not on carbon 1)

Question 3

When secondary or tertiary amines contain the same alkyl group prefixes _ or _ are used.

Answer 3

di-

tri-

Question 4

When 2 or more different groups are attached to a nitrogen atom the compound is named as a _ of the larger group.

Answer 4

N-substituted derivative

Question 5

The lone pair of electrons on the N of amines can accept a proton to form what type of bond?

Answer 5

dative covalent bond

Question 6

Give 2 equations for the preparation of a primary, aliphatic amine

Answer 6

haloalkane + ammonia -> ammonium salt

ammonium salt + aqueous alkali -> primary amine

Question 7

Why is ethanol as solvent needed for the preparation of a primary, aliphatic amine?

Answer 7

prevent substitution of haloalkane by water to produce alcohols

Question 8

Why is an excess of ammonia needed for the preparation of a primary, aliphatic amine?

Answer 8

prevent/reduce further substitution of the amine group

Question 9

What reagents and conditions are needed for the preparation of aromatic amines e.g. phenylamine?

Answer 9

1. Sn / conc. HCl
2. Excess NaOH(aq)
   under reflux

Question 10

Define amino acid

Answer 10

organic compound containing both amine, NH2, and carboxylic acid, COOH, functional groups

Question 11

Give the general formula for an alpha-amino acid

Answer 11

RCH(NH2)COOH

Question 12

amine group + acid ->

Answer 12

salt N+H3 + Cl- etc

Question 13

carboxylic acid group + alkali(aq) ->

Answer 13

salt COO-Na+ etc + water

Question 14

Describe the esterification of carboxylic acids

Answer 14

carboxylic acids are esterified by heating with an alcohol in the presence of conc. sulfuric acid
the acidic conditions protonate the basic amine group

Question 15

What are amides?

Answer 15

products of reactions of acyl chlorides with ammonia and amines

Question 16

Optical isomerism is found in molecules that have a _

Answer 16

chiral centre

Question 17

Define chiral centre

Answer 17

a carbon atom attached to four different atoms or groups

Question 18

Define enantiomers

Answer 18

optical isomers; stereoisomers that are non-superimposable mirror images of each other

Question 19

How can you identify chiral centres?

Answer 19

eliminate double bonds, any methyl groups and CH2s

Question 20

Define condensation polymerisation

Answer 20

the joining of monomers with the loss of a small molecule e.g. water or HCl
example: lactic acid -> poly(lactic acid) PLA

Question 21

State two types of linkage

Answer 21

ester linkage COO and amide linkage CONH

Question 22

What should you be aware of in the base hydrolysis of polyesters and polyamides?

Answer 22

COOH groups will react with a base e.g. NaOH(aq) to form COO-Na+

Question 23

What should you be aware of in the acid hydrolysis of polyamides?

Answer 23

The NH2 groups will react with an acid e.g. H+(aq) to form N+H3

Question 24

Name 2 features of addition polymerisation

Answer 24

monomer with C=C double bond

backbone of polymer is a continuous chain of carbon atoms

Question 25

Name 3 possible features of condensation polymerisation

Answer 25

two monomers, each with two functional groups
or
one monomer with two different functional groups
contains ester or amide linkages

Question 26

For what reasons could a molecule be described as an amino acid?

Answer 26

amino group and carboxylic acid group attached to the same carbon

Question 27

What symbol is used to indicate a chiral carbon on the structure of a molecule?

Answer 27

asterisk, *

Question 28

Name two key properties of amines

Answer 28

nucleophile

base-proton acceptor