GB655668A - Improvements in or relating to methods of making sulphenamides - Google Patents

Abstract

Sulphenamides are prepared by the oxidation in a wholly aqueous medium of a mixture of a free mercaptothiazole and at least three molecular proportions of a primary amine stronger than ammonia. The following amines are mentioned: benzylamine, ethylene diamine, n-butylamine, n-amylamine, ethylamine, propylamine, allylamine, and hexahydrobenzylamine. Mercaptans such as 2-mercaptothiazoline, 2-mercapto-4-ethylthiazole, and 2-mercapto-4 : 5-dimethylthiazole may be used; particularly preferred are mercapto-arylthiazoles such as 2-mercaptobenzothiazole, 2-mercaptonaphthothiazole, 2-mercaptomethylbenzothiazole, and 2-mercaptochlorobenzothiazole. Hypochlorites, e.g. alkali metal salts, are the preferred oxidizing agents, although other compounds may be employed such as hydrogen peroxide, chlorine, potassium ferricyanide and potassium persulphate. In the examples, a suspension of mercaptobenzothiazole in water is oxidized with sodium hypochlorite solution in the presence of (1) cyclohexylamine to give cyclohexylaminothiobenzothiazole; (2) sec.-butylamine to give sec.-butylaminothiobenzothiazole; (3) monoethanolamine to give b -hydroxyethylaminothiobenzothiazole; (5) o-cyclohexylcyclohexylamine; and (6) methylamine; in (4) cyclohexylamine is oxidized under the same conditions with hydrogen peroxide. The Specification as open to inspection under Sect. 91 comprises the statement that any organic mercaptan may be used in the reaction, which may be performed in an inert organic solvent. Specified mercaptans are thiophenol, thio - b - naphthol, 2 - mercapto - 4 : 5 - dihydroglyoxaline, 2-mercaptobenzimidazole, and 2-mercaptobenzoxazole. This subject-matter does not appear in the Specification as accepted.ALSO:Sulphenamides, made according to the process of the Group IV (b) Abridgment, and of formula R.S.NHR1 (where R is a thiazolyl radical, e.g. benzothiazolyl, and R1 is organic) are used as accelerators for the vulcanization of rubber; they may be employed alone or in conjunction with basic nitrogen-containing accelerators, e.g. di-o-tolylguanidine and diphenylguanidine phthalate. In an example, pale crepe rubber mixed with zinc oxide and stearic acid is vulcanized in the presence of b -hydroxyethylaminothiobenzothiazole and diphenylguanidine. The Specification as open to inspection under Sect. 91 comprises also the use of sulphenamides R.S.NHR1, where R is any organic group, e.g. phenyl, b -naphthyl, 2-benzimidazolyl, 2-benzoxazolyl and the radical derived from 4 : 5-dihydroglyoxaline. This subject-matter does not appear in the Specification as accepted.