From the primary amines are derived the diazo compounds and azo compounds; closely related are the hydrazines (q.v.).
The acid finds considerable use in organic chemistry, being employed to discriminate between the different types of alcohols and of amines, and also in the production of diazo, azo and diazo-amino compounds.
The diazo group takes up the para position with regard to the hydroxyl group, and if this be prevented it then goes into the ortho position.
Meta-oxyazobenzene, C 6 H 5 N: N(1)C 6 H 4 OH(3), was obtained in 1903 by P. Jacobson (Ber., 1903, 36, p. 4 0 93) by condensing ortho-anisidine with diazo benzene, the resulting compound being then diazotized and reduced by alcohol to benzene-azometa-anisole, from which meta-oxyazobenzene was obtained by hydrolysis with aluminium chloride.