22.10: Reactions of Esters

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Esters can be cleaved back into a carboxylic acid and an alcohol by reaction with water and a catalytic amount of acid.

General Reaction

Example 1:

Mechanism

1) Protonation of the Carbonyl

2) Nucleophilic attack by water

3) Proton transfer

4) Leaving group removal

The resulting carbonyl is deprotonated by water to reform H₃O⁺ and yield the neutral carboxylic acid.

Esters can be cleaved back into a carboxylic acid and an alcohol by reaction with water and a base

The reaction is called a saponification from the Latin sapo which means soap. The name comes from the fact that soap used to me made by the ester hydrolysis of fats. Due to the basic conditions a carboxylate ion is made rather than a carboxylic acid.