Yellow,organe and red azo cpds - for dyeing/printing acrylonitrile base fibres

Cpds. of formula (I): (where D is the residue of a diazo component, pref. of the benzene or naphthalene series, R1 and R2 can be H) contain >=1 carboxyl gp. not linked directly to the ring in the posn. next to the azo bridge. They are prepd. by coupling diazo derivs. of amines D-NH2 with appropriate hydroxypyridines.