27.1 Amines

Question 1

Aliphatic amine

Answer 1

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

Question 2

Aromatic amine

Answer 2

Nitrogen atom is attached to an aromatic ring

Question 3

Why do amines behave as bases?

Answer 3

Lone pair of electrons on the nitrogen atom can accept a proton

Question 4

What happens when an amine accepts a proton?

Answer 4

A dative covalent bond is formed between the lone pair of electrons on the nitrogen atom and the proton

Question 5

How are primary amines formed?

Answer 5

Ammonia reacts with a haloalkane to form an ammonium salt
Add aqueous alkali to generate the amine from the salt

Question 6

Conditions for formation of primary amine

Answer 6

Ethanol is used as the solvent - prevents substitution of haloalkane by water to form alcohols
Excess ammonia is used - reduces further substitution of the amine group to form secondary and tertiary amines

Question 7

How are secondary and tertiary amines formed?

Answer 7

React primary amine with haloalkane
Obtain secondary amine from salt by reacting with NaOH

Question 8

Preparation of aromatic amines

Answer 8

Reduction of nitrobenzene
Heated under reflux with Sn and HCl to form phenylammonium
React with excess NaOH to produce phenylamine