Carboxylic acids and esters

The structures of:
- carboxylic acids
- esters.

Carboxylic acids are weak acids but will liberate CO₂ from carbonates.

Carboxylic acids and alcohols react, in the presence of an acid catalyst, to give esters.

Common uses of esters (eg in solvents, plasticisers, perfumes and food flavourings).

Vegetable oils and animal fats are esters of propane-1,2,3-triol (glycerol).

Esters can be hydrolysed in acid or alkaline conditions to form alcohols and carboxylic acids or salts of carboxylic acids.

Vegetable oils and animal fats can be hydrolysed in alkaline conditions to give soap (salts of long-chain carboxylic acids) and glycerol.

Biodiesel is a mixture of methyl esters of long-chain carboxylic acids.

Biodiesel is produced by reacting vegetable oils with methanol in the presence of a catalyst.

Acylation

The structures of:
- acid anhydrides
- acyl chlorides
- amides.

The nucleophilic addition–elimination reactions of water, alcohols, ammonia and primary amines with acyl chlorides and acid anhydrides.

The industrial advantages of ethanoic anhydride over ethanoyl chloride in the manufacture of the drug aspirin.

Students should be able to outline the mechanism of nucleophilic addition–elimination reactions of acyl chlorides with water, alcohols, ammonia and primary amines.

Required practical 10

Preparation of:
- a pure organic solid and test of its purity
- a pure organic liquid.