GB420444A - Process for the manufacture of compounds of the diphenylamine sulphone series - Google Patents

Abstract

Diphenylamine sulphone compounds are manufactured by treating diphenylamine compounds, having in each nucleus a free o-position to the imino group, with fuming sulphuric acid of an SO3-content of more than 25 per cent, and at a temperature above about 50 DEG C., preferably with fuming sulphuric acid of 60--70 per cent SO3-content at 80--125 DEG C., and, if desired, splitting off the sulphonic groups from the products by known methods, e.g. by heating at elevated temperature and under superatmospheric pressure in dilute mineral acids. The products may be employed in the manufacture of dyestuffs and synthetic drugs. In examples: (1) diphenylamine is dissolved in sulphuric acid monohydrate and treated with fuming sulphuric acid of 65 per cent SO3-content at about 80 DEG C. and the product is poured on to ice and neutralized with milk of lime yielding the calcium salt of diphenylamine sulphone-tetrasulphonic acid, which is transformed into the potassium salt by the action of potassium carbonate; this product, or the calcium or sodium or other salt, is heated in an autoclave with aqueous sulphuric acid to produce diphenylamine sulphone; (2) 3-hydroxydiphenylamine is similarly treated at 120--130 DEG C. and worked up as in (1) to produce the potassium salt of 2-hydroxydiphenylamine sulphone-tetrasulphonic acid, which is converted into 2-hydroxydiphenylamine sulphone; in a similar manner phenyl-m-toluylenediamine (CH3:NH2:C6H5NH = 1 : 2 : 4) yields a product which is probably 2- or 4-amino-3-methyldiphenylamine sulphone, 3-methoxydiphenylamine (obtainable by methylating 3-hydroxydiphenylamine) yields 2 - methoxy - diphenylamine sulphone, and 3-chlorodiphenylamine yields 2-chlorodiphenylamine sulphone; (3) 4-aminodiphenylamine is dissolved in sulphuric acid monohydrate and treated with fuming sulphuric acid of 60 per cent SO3-content at 120--130 DEG C., the product being worked up as in (2) to produce the potassium salt of 3-aminodiphenylamine sulphone-1 : 6 : 8-trisulphonic acid, which is treated by the method of (1), yielding a mixture of 3-hydroxy-and 3-amino-diphenylamine sulphone. The Specification as open to inspection under Sect. 91 refers also to the use of N-methyl- and N-ethyl-diphenylamine as starting materials, the products being stated to be 3-methyl- and ethyl-diphenylamine sulphones. This subject-matter does not appear in the Specification as accepted.