A description applied to a @[email protected] whose @[email protected] each possess two alternative and strongly interacting distinguishable reactive centres, to either of which a @[email protected] may be made in a reaction: the centres must be connected in such a way that reaction at either site stops or greatly retards subsequent attack at the second site. The term is most commonly applied to @[email protected], for example the enolate ion:
(which may react with @[email protected] either at the β-carbon atom or at oxygen) or γ-pyridones, and also to the vicinally ambident cyanide ion, cyanate ion, thiocyanate ion, sulfinate ion, nitrite ion and unsymmetrical @[email protected] Ambident electrophiles are exemplified by carboxylic @[email protected]
which react with nucleophiles either at the carbonyl carbon or the alkoxy carbon. Molecular entities, such as @[email protected] of dicarboxylic acids, containing two non-interacting (or feebly interacting) reactive centres, are not generally considered to be ambident and are better described as 'bifunctional'. The Latin root of the word implies two reactive centres, but the term has in the past also incorrectly been applied to chemical species with more than two reactive centres. For such species the existing term '@[email protected]' (or, better, '@[email protected]') is more appropriate.
See also:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1082 [Terms] [Paper]