Reactions of Amides (Cambridge International A-Level Chemistry)

Spec point — 34.3.2

Reactions of Amides

• Amides are formed from the condensation reaction of carboxylic acids or acyl chlorides with ammonia or amines

• The amide group (CONR₂) in these compounds can undergo reactions including

  • Hydrolysis with **aqueous alkali **or aqueous acid
  • Reduction with LiAlH₄****

Hydrolysis of amides

• The -CON- group in substituted amides links two hydrocarbon sections of their molecules together

• This amide link can be broken down by hydrolysis by refluxing it with an acid or alkali

• The products of a non-substituted amide are:

  • Carboxylic acid
  • Ammonia

• The products of a substituted amide are:

  • Carboxylic acid
  • Primary amine

Hydrolysis of substituted and non-substituted amides

The hydrolysis products include a carboxylic acid along with ammonia for a non-substituted amide and an amine for a substituted amide

• When hydrolysed by refluxing in excess acid, the ammonia or amine produced will form an ammonium salt
• When hydrolysed by refluxing in excess base, the carboxylic acid produced will be deprotonated to form a carboxylate ion

Comparing amide hydrolysis in acidic and alkaline conditions

Amides are hydrolysed to carboxylic acids and ammonia or primary amines when refluxed with acid or alkali

Reduction of amides

• The C=O group in amides can be reduced by the strong reducing agent LiAlH₄ to form an amine

• The products of a non-substituted amide are:

  • A primary amine and water

• The products of a substituted amide are:

  • A secondary amine and water

Reduction of amides

Amides can be reduced to amines using LiAlH₄