Illustrated Glossary of Organic Chemistry

Aldol reaction: An addition reaction between two aldehydes (or an aldehyde and a ketone) resulting in a β-hydroxy aldehyde. Similar reaction between two ketones gives a β-hydroxy ketone. Subsequent dehydration produces an α,β-unsaturated aldehyde or ketone. The combination of an aldol reaction with subsequent dehydration is an aldol condensation. Both the aldol and dehydration steps may be promoted by base or acid.