GB445538A - Manufacture of 2-methyl-ª‰ª‰-naphththiazole and substitution products thereof - Google Patents

Abstract

2-Methyl-b : b <1>-naphththiazole containing a mercapto group in the naphthalene nucleus is made by reducing in acid solution a 2-naphthylamine-disulphonic acid, containing one of the sulpho groups in the 3-position, to the corresponding di-mercapto compound and condensing the latter with acetic acid, acetic anhydride or acetyl chloride. The product may be heated with a reducing metal to give 2-methyl-b : b <1>-naphththiazole, or treated with dimethyl sulphate in alkaline solution to give a methyl thio-ether. The reduction of the 2-naphthylamine-disulphonic acid is preferably carried out by converting the sodium salt to the corresponding sulphochloride, and reducing the latter with tin or zinc in acid solution. In examples: (1) sodium 2-amino-3 : 6-naphthalenedisulphonate is converted by means of phosphorus pentachloride to the sulphochloride, the latter is reduced by zinc and hydrochloric acid to the di-mercapto compound, which is then condensed with acetic anhydride; (2) 2-methyl-7-sulphhydroxy-b : b <1>-naphththiazole, obtained as in example 1, is heated with iron powder to give 2-methyl-b : b <1>-naphththiazole and in (3) it is treated with dimethyl sulphate to give the methyl thio-ether; (4) sodium 2 - amino - 3 : 7 - naphthalene disulphonate is treated as in examples 1 and 3.