Azo dyes; azo dyes, forming upon the material; cellulose esters, dyeing.--Water-insoluble azo dyestuffs are manufactured by coupling the diazo compounds of sulphones of the general formula <FORM:0456343/IV/1> or <FORM:0456343/IV/2> where R is an aliphatic radicle which may be substituted, X and Y are hydrogen or any substituents (except amino, carboxylic acid or sulphonic acid groups), and the naphthalene nucleus may contain any further substituents (except amino, carboxylic acid or sulphonic acid groups), with aromatic amines coupling in p-position to the amino group and containing no sulphonic acid, carboxylic acid or sulphonic or carboxylic arylamide group, in which aromatic amines the hydrogen atoms of the amino group may be wholly or partially replaced by alkyl or hydroxyalkyl radicles, such compounds being included in which the nitrogen atom forms part of a hydrogenated heterocyclic ring, which may be condensed to the aromatic nucleus. The products dye acetate artificial silk from aqueous baths, preferably in the presence of emulsifying media, yellow, orange red, violet and blue shades. Those which contain a free amino group may be diazotized and developed on the fibre, giving red, violet and blue to bluish green dyeings. Examples describe the preparation of the following dyestuffs: (1) 4-aminophenylmethylsulphone --> 3-hydroxy-1 : 2 : 3 : 4-tetrahydro-1<1> : 2<1>-naphthoquinoline; the product dyes acetate artificial silk bluish red shades; (2) 4-aminophenylmethylsulphone --> a -naphthylamine (scarlet shades); (3) 3-nitro-4-aminophenylmethylsulphone --> 1 - methyl - 4 - methoxy-5-hydroxyethyl-n-butylaminobenzene (yellowish red shades); (4) 4-aminophenylhydroxyethyl-sulphone --> dimethylaniline or hydroxyethylmethylaniline (light orange shades); (5) 4 - aminophenylhydroxyethylsulphone --> diphenylamine (yellowish orange shades); (6) 3 - chloro - 4 - aminophenyl - 1 - hydroxyethylsulphone --> diethylaniline or hydroxyethylmethylaniline or N-dihydroxyethyl-3-toluidine (reddish orange shades); the diazo component may be replaced by 3-chloro-4-aminophenylethylsulphone or 3-chloro- or bromo-4-aminophenylmethylsulphone (reddish orange shades) or by 3-methoxy- or methyl-4-aminophenylhydroxyethylsulphone (yellowish orange shades); (7) 2 : 5 - dichloro - 4 p - aminophenylmethylsulphone --> N - hydroxyethylmethylaniline (scarlet shades); the coupling component may be replaced by dihydroxyethyl-m-toluidine or the diazo component by 2 : 3- or 3 : 5 - dichloro - 4 - aminophenylmethylsulphone; (8) 1 - naphthylamine - 4 - methylsulphone --> N - hydroxyethylbutyl - 3 - toluidine (scarlet shades); (9) 1 - naphthylamine - 4 - methylsulphone --> 3-toluidine (orange shades which can be diazotized on the fibre and developed with b -naphthol or 2 : 3-hydroxynaphthoic acid to red and Bordeaux shades respectively); (10) 1 - naphthylamine - 4 - ethylsulphone --> 3 : 7-dihydroxy-1 : 2 : 3 : 4-tetrahydro-1<1> : 2<1>-naphthoquinoline (light blue shades); (11) 1-naphthylamine - 4 - hydroxyethylsulphone --> 1-methyl - 4 - methoxy - 5 - aminobenzene (reddish orange shades which may be diazotized on the fibre and developed with b -naphthol or 2 : 3-hydroxynaphthoic acid to reddish and bluish violet shades respectively); (12) 1-naphthylamine - 4 - hydroxyethylsulphone --> 3 : 7-dihydroxy-1 : 2 : 3 : 4-tetrahydro-1<1> : 2<1>-naphthoquinoline (light blue shades); (13) 2-bromo-1-naphthylamine - 4 - methylsulphone --> 3 : 7-dihydroxy-1 : 2 : 3 : 4-tetrahydro-1<1> : 2<1>-naphthoquinoline (blue shades). A table gives the shades obtained from further dyestuffs, the following additional coupling components being specified : 1 - N - hydroxyethylnaphthylamine, 1 - amino - 5 - naphthol, N-diethyl-m-toluidine, 1-amino-2-naphthol ethyl ether, 3-chloro-N-dihydroxyethylaniline, N - dihydroxyethylaniline, 2-toluidine and 1-hydroxyethylamino5 - naphthol. Specifications 257,619, [Class 2 (iii)], and 446,745 are referred to. 3 - Nitro - 4 - aminophenylmethylsulphone is obtainable by nitrating 4-chlorophenylmethylsulphone and then replacing the chlorine atom by an amino group by the action of ammonia. 4-Aminophenylhydroxyethylsulphone is obtainable by decomposing 4 : 4<1>-dinitrodiphenyl-disulphide to 4-nitrophenyl mercaptan, reacting this with glycol chlorhydrin, oxidizing the resulting sulphide to the sulphone by means of hydrogen peroxide in glacial acetic acid and reducing the nitro group. 3 - Chloro - 4 - aminophenyl - 1 - hydroxyethylsulphone is obtainable by thiocyanating o-chloraniline, decomposing the product to the corresponding mercaptan, reacting this with glycol chlorhydrin, acetylating, oxidizing to the sulphone and splitting off the acetyl group. 3-Chloro-, 3-bromo-, 3-methoxy-, 3-methyl-, 2 : 5- and 2 : 3-dichloro-4-aminophenylmethylsulphones are obtainable by thiocyanating o-chloraniline, o-bromaniline, o-anisidine, o-toluidine, 2 : 5- and 2 : 3-dichloraniline respectively, decomposing the products to the corresponding mercaptans, converting these to the methyl thioethers and then proceeding as in the preceding paragraph. 3 : 5-Dichloro-4-aminophenylmethylsulphone is obtainable by diazotizing 3 : 5-dichloro-1 : 4-phenylenediamine, reacting with potassium xanthogenate, converting the product to the mercaptan and proceeding as in the preceding paragraph. 1 - Naphthylamine - 4 - methyl-, ethyl- and hydroxyethyl-sulphones are obtainable by transforming 1-acetylaminonaphthalene-4-sulphonic acid into the sulphochloride, reducing this to the sulphinic acid, alkylating to produce the sulphone and saponifying. 2-Bromo-1-naphthylamine-4-methylsulphone is obtainable similarly from 2-bromo-1-naphthylamine-4-sulphonic acid. 1 - Methyl - 4 - methoxy - 5 - hydroxyethyl - n - butylaminobenzene is obtainable by alkylating 1 - methyl - 4 - methoxy - 5 - aminobenzene with a n-butyl halide and an agent for introducing a hydroxyethyl group, e.g. ethylene oxide or ethylene chlorhydrin. N-Hydroxyethylbutyl-3-toluidine is obtainable similarly from 3-toluidine.