4-Sulphomethyl substituted hydroxypyridone azo dyestuffs

An azo dyestuff of the formula ##STR22## in which D is phenyl which is unsubstituted or substituted by sulfo, chloro, bromo, methyl, nitro, cyano, methylsulfonyl, trifluoromethyl, carbomethoxy, carboethoxy, hydroxy, amino, ortho methoxy, acetylamino, carboxy, cyclohexyloxycarbonyl, isopropylaminosulfonyl, sulphamato, phenylazo, sulfophenylazo, disulfonaphthylazo or a fiber reactive group capable of reacting with the hydroxy groups of cellulose or the amido groups of polyamide;

• napthyl substituted by sulfo, acetylamino, .gamma.-isopropyloxypropylaminosulfonyl or hydroxy;
• thiazole;
• quinoline;
• benzthiazole substituted by methyl;
• 1,3,5-thiadiazole or benzisothiazole;
• R is hydrogen;
• alkyl of 1-4 carbon atoms;
• .beta.-hydroxyethyl;
• .beta.-chloroethyl;
• .beta.-acetylaminoethyl;
• phenyl which is unsubstituted or substituted by methoxy, chloro or acetamino;
• benzyl;
• or a group of the formula --(CH.sub.2).sub.n --NH--Z wherein
• n is 1-4,
• Z is a fiber reactive group capable of reacting with the hydroxy groups of cellulose or the amido groups of polyamides;
• and
• R' is hydrogen, chloro, bromo, cyano, carbonamido, nitro, nitroso, amino, methylsulfonyl or acetylamino.