A (usually stepwise) reaction in which two or more reactants (or remote reactive sites
within the same
molecular entity ) yield a single main product with accompanying formation of water or of some other
small molecule, e.g. ammonia, ethanol, acetic acid, hydrogen sulfide. The mechanism
of many condensation reactions has been shown to comprise consecutive
addition and
elimination reactions, as in the base-catalysed formation of (
E)-but-2-enal (crotonaldehyde) from acetaldehyde,
via 3-hydroxybutanal (aldol). The overall reaction in this example is known as the aldol
condensation. The term is sometimes also applied to cases where the formation of water
or another simple molecule does not occur, as in '
benzoin condensation'.
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1099