Reactions of Amides (CIE A Level Chemistry)

• 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