GB288554A - Manufacture of vat-dyestuffs - Google Patents

Abstract

288,554. I. G. Farbenindustrie Akt.- Ges. April 11, 1927, [Convention date]. Samples furnished. Thioindigo dyes; oxythionaphthenes.-3 : 5 : 6- Trimethylbenzene-1-thioglycollic acid or a substitution product having a carboxy, cyano or a carboxylic acid amido group in the 2-position is treated with a ring closing agent in order to produce the corresponding 3-hydroxythionaphthene, which by oxidation gives 4: 6 : 7 : 4<1> : 6<1> : 71- hexamethyl-bis-thionaphthene indigo. The 4 : 6 : 7- trimethylhydroxythionaphthene or its active 2- derivatives mav also be condensed with the usual indigoid components to give vat-dyestuffs. In an example, 3 : 5 : 6-trimethylbenzene-1-thioglycollic-2-carboxylic acid nitrile is treated in caustic soda solution with sodium sulphide and the resulting sodium salt of 4: 6 : 7-trimethyl-3- amino-1-thionaphthene-2-carboxylic acid salted out. It is converted into the 4 : 6 : 7-trimethyl-3- oxythionaphthene by treatment in solution with dilute sulphuric acid and is then oxidized to the dyestuff, which dyes cotton from a yellow vat, fast, clear red shades. 3: 5: 6 - Trimethylbenzene - 1-thioglycollic-2- carboxylic acid nitrile can be prepared by exchanging the amino group of 2-amino-1-nitro- 3 : 5 : 6-trimethylbenzene for cyanogen, reducing the nitro group to amino and replacing the latter, in known manner by the thioglycollic acid residue. 3 : 5 : 6 - Trimethylbenzene-T-carboxylic acid amide-1-thioglycollic acid is prepared by hydrolysis of the 3 : 5 : 6-trimethylbenzene-2-cyano-1- thioglycollic acid. 3 : 5 : 6 - Trimethylbenzene-2-carboxylic-1-thioglycollic acid' is obtained from 2-amino-1-nitro- 3 : 5 : 6-trimethylbenzene, by exchanging the amino group for the cyano group and hydrolyzing, reducing the nitro group, and replacing the amino group by the thioglycollic group in known manner.