GB355783A - - Google Patents

Abstract

Stilbene dyes giving very bright yellow and orange shades, fast to alkali, on cotton, are obtained by the action of oxidizing agents on the dyestuffs obtained by condensation of 1 mol. of dinitrostilbenedisulphonic acid with 1 or 2 mols. of aminoarylbenzothiazolesulphonic acids. The yield is greater than in the corresponding process described in Specification 18990/97, [Class 2, Acids and salts, Organic &c.], employing dinitrodibenzyldisulphonic acid in place of the dinitrostilbenedisulphonic acid, the products are in a more highly oxidized state, and their shades are more orange and less green. Specified aminoarylbenzothiazolesulphonic acids are the sulphonic acids of dehydrothiotoluidine, dehydrothioxylidine, and dehydrothiocumidine, primuline, and xylidine-primuline. The following examples are specified: (1) The dyestuff paste obtained from dinitrostilbenedisulphonic acid and dehydrothiotoluidinesulphonic acid according to Example 6 of Specification 21399/97, [Class, 2, Acids and salts, Organic &c.] is heated at 50 DEG C. with a solution obtained by passing chlorine into a 10 per cent solution of caustic soda; the product gives reddish yellow dyeings, fast to alkali, on cotton. (2) Chlorine is passed into a boiling alkaline suspension of the dyestuff obtained by boiling for 8 hours a 3,5 per cent solution of caustic soda containing equimolecular proportions of the sodium salts of dinitrostilbenedisulphonic acid and dehydrothioxylidinesulphonic acid; the product gives bright yellow-orange dyeings, fast to alkali, on cotton. The Specification as open to inspection under Sect. 91 (3) (a) comprises also the similar oxidation of the dyestuffs obtainable by condensation with aminoarylbenzothiazolesulphonic acids of the products of the action of caustic soda on p-nitrotoluenesulphonic acid and refers to Specification 263,192, [Class 2 (iii), Dyes &c.]. This subjectmatter does not appear in the Specification as accepted.