3.3.9.1
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 (e.g. 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.
3.3.9.2
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.