GB768681A - New disazo metallisable dyestuffs - Google Patents

Abstract

2 - Amino - 4 - hydroxybenzthiazole is obtained by demethylating the corresponding 4-methoxy compound with hydrobromic or hydriodic acid or aluminium chloride. 2-Acetyl- and -benzoylamino-4-hydroxy-benzthiazoles are made by treating the above amine with acetic or benzoyl chlorides. 2-Phenyl-4-hydroxy-benzthiazole is made by demethylating with hydriodic acid or aluminium chloride the corresponding 4-methoxy compound obtained by heating the Schiffs' base from o-anisidine and benzaldehyde with two atomic properties of sulphur and distilling the product. Hydroxy-indazoles are made by heating the corresponding aminoindazoles with dilute sulphuric acid at 150-210 DEG C. under pressure. 1-(51-and 61-Indazyl)-3-methyl-5-pyrazolones are made by diazotizing the appropriate aminoindazole, reducing the diazo compound to the hydrazine, condensing with ethyl acetoacetate or diketene and ammonia and ring-closing with caustic soda. The products are dyestuff intermediates (cf. Group IV (c)). Specifications 697,977 and 753,573 are referred to.ALSO:The invention comprises dyestuffs which as free acids are of formula <FORM:0768681/IV(b)/1> where R is a phenyl residue with at least one OH, CO2H or OCH2CO2H group in a position ortho to the azo group, A stands for a group such that the coupling component HA is a hydroxyindazole, a 4-hydroxy-benzthiazole, 4-hydroxyacridine or 1-(51- or 61-indazyl)-3-methyl-5-pyrazolone and A is linked through the -N-N-group to the meta or para position of the phenyl nucleus B and R and A are so chosen that the dyestuff contains not more than two sulphonic acid groups. They may be made by diazotizing an appropriate aminobenzoylamino-naphthaleneazo dyestuff and coupling with one of the above components. The aminoazo dyestuff may be made by diazotizing an appropriate amine and coupling with the naphthol sulphonic acid in aqueous alkaline solution. Amines specified are 2-aminophenol-4-sulphonic acid, 4-chloro-2-aminophenol-6-sulphonic acid, 6-chloro-2-aminophenol-4-sulphonic acid, anthranilic acid and o-aminophenoxyacetic acid. Specified end coupling components are 2-amino-, acetamino-, -benzylamino- and -phenyl-4-hydroxybenzthiazole. For preparation of end components (see Group IV(b)). The dyestuffs dye cotton by an after-coppering process in red or blue shades. Examples are provided of the use of certain of the above specified components in the preparation of dyestuffs additional end components used being 4-hydroxy-acridine and -benzythiazole and 6-hydroxyindazole. In the Provisional Specification R is stated to be an aryl residue and B optionally to contain a methyl substituent. Specifications 697,977 and 753,573 [both in Group IV(b)], are referred to.