GB389511A - Process of producing o-aminoaryl mercaptans and derivatives thereof - Google Patents

Abstract

o - Aminoarylmercaptans; o - aminoarylthio - glycollic acids o-Aminoarylmercaptans are prepared by heating a 2-aminoarylenethiazole with dilute aqueous alkali under pressure, namely, with about 5-30 per cent caustic soda or potash under an excess pressure of from 5-250 lbs. per sq. in. Temperatures of from 100 DEG to 300 DEG and theoretical amounts of alkali may be used, and the mercaptan may conveniently be isolated as the corresponding thioglycollic acid; high yields are obtained. In examples: (1) 2-amino-6-ethoxybenzthiazole is hydrolysed by aqueous caustic soda at 160 DEG and under a pressure of 70-80 lbs. per sq. in., or by 20 per cent soda at 120 DEG C. and 25 lbs. per sq. in.; the o-aminothiophenol is isolated either as the zinc salt or as the corresponding thioglycollic acid by treatment with chloracetic acid; (2) 2-amino-4-methylbenzthiazole is hydrolysed by 25 per cent caustic soda at 190 DEG C. and 125 lbs. per sq. in.; the o-aminothiophenol is isolated as the thioglycollic acid. The treatment of naphthothiazoles and of arylenethiazoles containing substituents not undesirably affected by the alkali treatment is also mentioned. Specifications 306,590, [Class 2 (iii), Dyes &c.], and 361,306 are referred to. The Specification as open to inspection under Sect. 91 relates to the production of o-aminoarylmercaptans by heating arylenethiazoles generally with dilute aqueous caustic alkali under pressure, any 2-substituent being removed in the hydrolysis. This subject-matter does not appear in the Specification as accepted.