2-Amino-4-hydroxybenzthiazole is made by demethylating 2-amino-4-methoxybenzthiazole with hydrobromic or hydriodic acids or aluminium chloride and the amino group subsequently acetylated or benzoylated. 4-Methoxy2-phenyl-benzthiazole is made by distilling a mixture of o-anisidine, benzaldehyde and sulphur and demethylated with hydriodic acid to yield 4 - hydroxy - 2 - phenyl - benzthiazole. 4 - Hydroxy - 2 - methylbenzoxazole is made by acetylating 2-amino-1,3-dihydroxybenzene with subsequent hydrolysis. 4,41-Dihydroxy-2,21-benzthiazoyl urea is made by treating 2-amino - 4 - hydroxybenzthiazole with phosgene in aqueous caustic soda solution. The products are dyestuff intermediates, (c.f. Group IV (c)).ALSO:The invention comprises dyestuffs which contain a group of formula <FORM:0761776/IV(b)/1> where X is H or C1 and the N atom #s to the OSO3H group is in a heterocyclic ring. They may be made by sulphating appropriate dyestuffs containing OH in place of OSO3H. Specified sulphating agents are sulphuric and chlorsulponic acids particularly suitable being reaction products of tertiary amines such as pyridine, 5-ethyl-2-methyl - pyridine and triethylamine with sulphur trioxide, addition compounds of sulphur trioxide with amides e.g. dimethyl- and diethyl - form - and acet - amides, tetramethyl urea, formyl- and acetyl - piperidides, formyl-morphodile, tetramethyladipamide, dimethyl - benzamide and -urethane, N - methyl - acetamide and - phthalimidine and N, N - diethyl - p - toluenesulphonamide and addition products of chlorosulphonic acid and amides such as form - and acet - amides, urea, dimethyl - acetamide and formanilide, an optional excess of amine or amide acting as a diluent. A preferred sulphating agent is made by reacting sulphur trioxide and triethylamine and it may be melted with the dyestuff at 90-120 DEG C. or reacted therewith in an aqueous medium. Specified heterocyclic coupling components are 8 - hydroxy - quinoline and - cinnoline, 4 - hydroxy - acridine and - benzthiazole, 2 -phenyl-, -acetyl - and - benzoyl - amino - 4 - hydroxybenzthiazoles, 4 - hydroxy - 2 - methylbenzoxazole and 7 - chloro - 8 - hydroxy - quinoline. Specified amines which may be diazotized and coupled with the heterocyclic components are benzidine, dianisidine, 4,41 - diamino - azobenzene, -benzanilide, -diphenylamine, -diphenyl urea and -diphenyl sulphone, 31, 4 - diamino - 3, 41 - dimethoxy - benzanilide, 3, 31 - diamino - benzanilide and - diphenyl urea 1, 5 - and 2, 6 -diaminonaphthalene, 3, 6 - diaminocarbazole, 1, 8 - dichloro- 3, 6 - diamino - carbazole, 2, 5 - bis -(41 -aminophenyl) - 1, 3, 4 - oxadiazole, aniline, 2 - naphthalamine, 6 - aminoindazole and 2 - (41 - aminophenyl) - 6 - methylbenzathiazole. A preferred class of dyestuffs is obtained from tetrazotized diamines of formula NH2 - X - NH2 where X is a linking group so that NH2 groups are directly attached to aromatic nuclei these specified being benzene, naphthalene, acridine and carbazole nuclei, <FORM:0761776/IV(b)/2> where Y is a direct link, - NH -, - S -, - SO2-, - NO = N -, - N = N -, - NHCONH -, CONH -, - OCH2CH2O -, <FORM:0761776/IV(b)/3> and a system containing a multiplicity of azo groups. The dyestuffs dye cellulosic wool, nylon and other superpolyamide and superpolyester and cellulose acetate fibres the preferred classes being especially suitable for dyeing cellulosic fibres particularly by an acid after-coppering process which results in the removal of the OSO3 H groups to give an insoluble metal complex fixed on the fibre. A preferred class of dyestuffs for use in after-coppering processes is one in which the dyestuffs contain no solubilizing groups additional to the sulphate group or in which any additional solubilizing group is rendered less effective on metallization such as an #s, #s1-azo metallizable system. If the additional solubilizing group is not part of an #s, #s1 - system it should be linked to the sulphate group by a conjugated system. Examples and a Table are provided illustrating the preparation of sulphated dyestuffs from certain of the above components additional amines used to those specified being m- and pphenylene diamines, the bis - (4 - aminophenyl) ether of ethylene glycol, 4 - amino- and 4, 41 - diamino - stillbenes, 3, 6 - diamino - acridine, 2, 8 - diamino - 3, 6 - diethoxy - and 2, 8 - diamino - acridine, 2, 8-diamino - 3, 6 - diethoxy - and 2, 8 - diamino-N-methyl - acridines, 2, 7 - diamino-fluorene and - diphenylene sulphone, bis - (3 - methoxy - 4 - aminophenyl) - methane, di - (41-aminodiphenylether - 1) - and di - paminophenyl sulphides, bis - 1, 2 - p - aminophenylethane, 4, 41 - diamine - 3 - nitrodiphenyl, p - aminonitrobenzene, p - diethylaminoaniline and the dyestuff dianisidine --> 1 - amino - 2 - methoxy - 5 - methylbenzene, additional heterocyclic coupling components being 2 - methyl - and - amino - 4 - hydroxybenzthiazole and 4, 41 - dihydroxy-2, 21 - benzthiazol urea, and further dyestuffs to be sulphonated are 2 - amino - 5 - nitro-phenol or -benzoic or -phenoxyacetic acids --> J - acid --> 8 - hydroxyquinoline (the nitro groups being reduced before the final coupling), 2 - amino - 5 - nitrophenol --> J acid and --> 8 - hydroxyquinoline treated with aqueous alkaline acid glucose solution before sulphation and 2 - aminophenol sulphuric acid ester --> resorcinol \sM 4 - amino - 41 - acetylaminodiphenyl --> 8 - hydroxyquinoline (after saponification of the acetylamino groups). The sulphated dyestuffs of the examples dye cellulosic, nylon and cellulose acetate fibres in shades of red, blue, yellow and grey by after-coppering processes. Specification 493,463 [Group IV] was laid open to inspection under Sect. 91 is referred to. This subjectmatter does not appear in the Specification as accepted.