Azo compound

Azo compounds are organic compounds bearing the functional group diazenyl (R−N=N−R′, in which R and R′ can be either aryl or alkyl groups).

IUPAC defines azo compounds as: "Derivatives of diazene (diimide), HN=NH, wherein both hydrogens are substituted by hydrocarbyl groups, e.g. PhN=NPh azobenzene or diphenyldiazene.", where Ph stands for phenyl group. The more stable derivatives contain two aryl groups. The N=N group is called an azo group (from French azote 'nitrogen', from Ancient Greek ἀ- (a-) 'not', and ζωή (zōē) 'life').

Many textile and leather articles are dyed with azo dyes and pigments.