Illustrated Glossary of Organic Chemistry

Transesterification: A process that converts one ester into another ester. The most common version involves carboxylate esters.

In this acid-catalyzed transesterification reaction, methyl benzoate (an ester) is reacted with ethanol (an alcohol) in the presence of sulfuric acid catalyst to produce ethyl benzoate and methanol. The reaction is a reversible equilibrium, so methanol is used in excess (it is the reaction solvent) to push the reaction equilibrium towards ethyl benzoate (via Le Chatelier's principle).

The same conversion can be achieved by reacting methyl benzoate with an excess of sodium ethoxide (an alkoxide and strong nucleophile).