diamide

A diamide is a compound that contains two amide functional groups within the same molecule. An amide group consists of a carbonyl (C=O) bonded to a nitrogen atom. Diamides can be symmetric or unsymmetric, and the two amide groups may be connected by a hydrocarbon chain of varying length or by different linkages. Well-known simple examples include malonamide (H2N-CO-CH2-CO-NH2), succinamide (H2N-CO-(CH2)2-CO-NH2), and adipamide (H2N-CO-(CH2)4-CO-NH2).

Nomenclature and structure vary, but the defining feature is the presence of two amide moieties in one molecule. The two nitrogens of the amide groups can carry hydrogen atoms or be substituted with alkyl or aryl groups, leading to a range of diamides with different properties.

Preparation commonly involves amidation steps on dicarboxylic acid derivatives. Diacids can be converted to diacid chlorides and then reacted with ammonia or primary amines to form the corresponding diamide. Alternatively, diesters or other activated carboxyl derivatives can be converted to diamides under suitable conditions. Symmetrical diamides can arise from reaction of a dicarboxylic acid with excess ammonia or amine, while unsymmetrical diamides result from selective modification of one end.

Properties and applications vary with structure. Amide nitrogens are relatively non-basic due to resonance, and diamides are typically less reactive toward hydrolysis than esters or anhydrides. Diamides occur as intermediates in organic synthesis, serve as ligands in coordination chemistry, and function as precursors or monomers in the production of polyamides and related polymers.

See also: amide, diamine, polyamide.