Disazo Pigment Dyestuffs

1,169,390. Disazo pigment dyes. FARBENFABRIKEN BAYER A.G. 22 May, 1967 [23 May, 1966], No. 23655/67. Heading C4P. The invention comprises disazo dyes free from SO3H groups, of formula wherein X are identical or different substituents, m is 0, 1, 2 or 3, B is a bivalent coupling component radical, Y is -O- or -NR- and R is H or an alkyl, aralkyl, carbocyclic or heterocyclic radical which may be substituted. The dyes are prepared from intermediate disazo dyes (obtained by coupling 2 mols. of a diazotized aminophthalic acid with a suitable coupling component) (i) by reaction with dehydrating agents, e.g. acetic acid, acetic anhydride, sodium acetate or ferric chloride to form the dyes, wherein Y is -O- or (ii) by reaction of the anhydride from (i) or the intermediate disazo dyes with ammonia or an amine R-NH 2 to form the dyes wherein Y is -NR-. The dyes are used to colour polymers in yellow and red shades. In examples, disazo dyes prepared from bis-N-acetoacetyl- or -hydroxynaphthoyl - phenylenediamine, bis - pyrazolonyl - phenylene and bis - amino - pyrazolyl- or -pyrazolonyl - diphenyl coupling components are described.