18B: Amines, amides, amino acids and proteins

Question 1

Identify the functional group.

Answer 1

(Primary) amine

Question 2

Identify the functional group.

Answer 2

Amide

Question 3

Identify the type of molecule.

Answer 3

Amino acid

Question 4

Reaction of butylamine with water:
Product.

Answer 4

Butylammonium hydroxide

Question 5

Describe the reaction:
Butylamine -> Butyl ammonium hydroxide

Answer 5

React with water

Question 6

Reaction of butylamine with acids:
Product.

Answer 6

Butylammonium salt

Question 7

Describe the reaction:
Butylamine -> Butyl ammonium salt

Answer 7

React with acid

Question 8

Reaction of butylamine with ethanoyl chloride:
Products.

Answer 8

N-Butylethanamide + HCl

Question 9

Describe the reaction:
Butylamine -> N-Butylethanamide

Answer 9

React with ethanoyl chloride,
Produces HCl

Question 10

Reaction of butylamine with halogenoalkanes:
Products.

Answer 10

Secondary amine + Hydrogen halide

Question 11

Describe the reaction:
Butylamine -> Secondary amine

Answer 11

React with halogenoalkane,
Produces hydrogen halide.

Question 12

Reaction of butylamine with Copper(II) ions:
Product.

Answer 12

Complex ions.

Question 13

Describe the reaction:
Butylamine -> Complex ion

Answer 13

React with Copper(II) ions.

Question 14

Explain the difference in basicity of ammonia, primary aliphatic and primary aromatic amines.

Answer 14

Aliphatic amines: Alkyl group pushes electrons onto the nitrogen,
so the lone pair is more available,
so basicity is higher than ammonia

Aromatic amines: Lone pair is partially delocalised in the benzene ring,
so the lone pair is less available,
so basicity is lower than ammonia.

Question 15

Describe the preparation of primary aliphatic amines from halogenoalkanes.

Answer 15

React with concentrated ammonia in ethanol.

Question 16

Describe the preparation of primary aliphatic amines from nitriles.

Answer 16

React with LiAlH₄ in dry ether

Question 17

Describe two methods for the preperation of primary aliphatic amines.

Answer 17

React halogenoalkane with concentrated ammonia in ethanol.

React nitrile with LiAlH₄ in dry ether.

Question 18

Describe a method for the preperation of primary aromatic amines.

Answer 18

React aromatic nitro-compound with tin and concentrated hydrochloric acid.

Question 19

Describe a method for the preperation of amides.

Answer 19

React acyl chloride with concentrated ammonia.

Question 20

State the type of reaction for the formation of a polyamide.

Answer 20

Condensation polymerisation.

Question 21

Explain the acidity and basicity of 2-amino acids in solution.

Answer 21

Forms zwitterions in moderate pH, as the amine group accepts a proton and the carboxylic acid group donates a proton.

Question 22

Explain the effect of aqueous solutions of 2-amino acids on plane-polarised monochromatic light

Answer 22

The 2 carbon is chiral (unless the R group is hydrogen), so they form optical isomers and rotate plane-polarised monochromatic light.

Question 23

When is a peptide bond formed?

Answer 23

When amino acids combine, by condensation polymerisation, to form a protein.

Question 24

Describe how to form the constituent amino acids from a protein.

Answer 24

Hydrolysis of the peptide bond.

Question 25

State a method to seperate amino acids.

Answer 25

Chromatography.