Illustrated Glossary of Organic Chemistry

Retro-aldol reaction: A reaction in which a β-hydroxy carbonyl compound decomposes into an aldehyde or ketone, plus another carbonyl compound. The formal reverse of the aldol reaction.


HO- or H3O+  Aldol reaction

HO- or H3O+  Retro-aldol reaction

β-Hydroxy ketone

In the presence of acid catalysis or base catalysis, acetophenone undergoes an aldol reaction with acetone, to give a β-hydroxy ketone product. This β-hydroxy ketone can be decomposed back into acetone and acetophenone in a base-catalyzed (or acid-catalyzed) retro-aldol reaction.