Amination is the process by which an amine group is introduced into an organic molecule. Enzymes which catalyse this reaction, are termed aminases. This can occur in a number of ways including reaction with ammonia or another amine such as an alkylation, reductive amination and the Mannich reaction. For example, -COOH --> -CONH2.
Alkylation is the addition of an alkyl group where acylation is the addition of an acyl group (-COCH3). Acylation has two steps; Acylation (the addition of an acylium ion) and then reduction. Reduction can often happen more than once.
Most commonly, amination reactions involve the use of the amine as the nucleophile and the organic compound as the electrophile. However, this sense of reactivity may be reversed for some electron-deficient amines, including oxaziridines, hydroxylamines, oximes, and other N–O substrates. When the amine is used as an electrophile, the reaction is called electrophilic amination. Electron-rich organic substrates that may be used as nucleophiles for this process include carbanions and enolates.