Patent GB-360533-A (GB)
Title: The manufacture of 4.5-dimethyl-7-chloro-oxythionaphthene and of indigoid dyestuffs derived therefrom
IPC: C09B7/00
Filed: 1930-08-22
Abstract: 4 : 5 - Dimethyl - 7 - chloro - oxythionaphthene is manufactured by converting 4-amino-1 : 2-dimethylbenzene (obtained from o-xylene by nitration and reduction) into 1 : 2-dimethyl-4-chlorobenzene-5-mercaptan, treating this with monochloracetic acid and carrying out ring closure of the 1 : 2-dimethyl-4-chlorobenzene-5-thioglycollic acid thus formed.  The preparation of 1 : 2-dimethyl-4-chlorobenzene-5-mercaptan is performed by one of the following methods: (a) 4-amino-1 : 2-dimethylbenzene sulphate is transformed by baking into 1 : 2-dimethyl-4-aminobenzene-5-sulphonic acid, the amino group is replaced by chlorine by the Sandmeyer method and the 1 : 2-dimethyl-4-chlorobenzene-5-sulphonic acid so formed is converted to the sulphochloride which is reduced to the mercaptan; (b) 4-amino-1 : 2-dimethylbenzene is chlorinated and the amino group is replaced by the xanthogenic ester group, which by saponification is converted into the mercapto group.  The 4 : 5-dimethyl-7-chloro-oxythionaphthene is converted into the symmetrical thioindigo derivative by oxidation, or into mixed thioindigo dyestuffs by condensing it with cyclic diketones or their 2-derivatives, such as isatins and naphthisatins, their chlorides and arylides, or with diketodihydrothionaphthenes and diketodihydronaphthothionaphthenes and their anils, or with acenaphthenequinone, or by condensing the anils of the corresponding diketodihydrothionaphthene with bodies containing a reactive methylene group.  (The various anils are prepared by treating the corresponding 3-oxythionaphthenes with a nitrosoaryl compound, in particular nitrosodimethylaniline.)  In examples: (1) 1 : 2-dimethyl-4-chlorobenzene-5-mercaptan prepared by method (a) is condensed in alkaline solution with monochloracetic acid and the 1 : 2-dimethyl-4-chlorobenzene-5-thioglycollic acid converted to 4 : 5-dimethyl-7-chloro-oxythionaphthene by treatment with chlorsulphonic acid at -10 to -15 DEG C. or by treating its acid chloride with aluminium chloride; (2) the mercapto compound is prepared by method (b) and further treated as in (1); (3) 1 : 2-dimethyl-4-chlorobenzene-5-thioglycollic acid is treated with chlorsulphonic acid at 20 DEG  C. yielding 4 : 5 : 4<1> : 5<1>-tetramethyl-7 : 7<1>-dichlorothioindigo; the same dyestuff is obtained by oxidizing 4 : 5-dimethyl-7-chloro-oxythionaphthene with potassium ferricyanide or other oxidizing agent in alkaline solution; the product dyes and prints cotton bright red violet shades; (4) 4 : 5-dimethyl-7-chloro-oxythionaphthene is condensed with 4-methyl 6-chloro-2 : 3-diketodihydrothionaphthene-2-anil; the the same dyestuff is obtained by condensing 4 : 5 - dimethyl - 7 - chloro-2 : 3 - diketodihydrothionaphthene-2-anil with 4-methyl-6-chloro-oxythionaphthene; the product dyes the fibre bright pink shades; (5) 4 : 5 - dimethyl - 7 - chloro - oxythionaphthene is condensed with 5 : 7-dibromoisatin chloride (obtained by the action of phosphorus pentachloride on 5 : 7-dibromoisatin); the product dyes the fibre violet shades; (6) 4 : 5-dimethyl-7-chloro-oxythionaphthene is condensed with 4-methyl-5-chloro-7-methoxyisatin chloride (obtained by the action of phosphorus pentachloride on 4-methyl-5-chloro-7-methoxyisatin); the product dyes and prints cotton bright blue shades.