GB438426A - Manufacture of acid dyestuffs - Google Patents

Abstract

Acid dyestuffs, of the probable general formula <FORM:0438426/IV/1> where X is hydrogen, alkyl or aryl, Y is alkyl or aryl, and Z indicates that the dyestuff contains sulpho-groups, are manufactured by condensing one molecular proportion of a p-halogenbenzaldehyde or a benzaldehyde-p-sulphonic acid with two molecular proportions of an a -alkyl- or a -arylindole unsubstituted in the b position, or an N-alkyl or N-aryl derivative thereof, sulphonating, oxidizing, and condensing the product with a primary p-alkoxyarylamine, or by condensing the benzaldehyde derivative with a sulphonic acid of the indole derivative, oxidizing, and condensing with the amine. In examples: (1) p-chlorobenzaldehyde is condensed with N-methyl-a -phenylindole and the product is sulphonated, oxidized and condensed with p-phenetidine; the product in the form of its sodium salt dyes wool and silk blue tints; (2) benzaldehyde-p-sulphonic acid is condensed with N-methyl-a -phenylindolesulphonic acid and the product is oxidized and condensed with p-anisidine; the product dyes wool and silk blue tints; (3) as in (2) but using N-methyl-a -methylindolesulphonic acid; the product dyes wool and silk reddish-blue tints. The Specification as open to inspection under Sect. 91 comprises also the use of a primary p - aryloxyarylamines, e.g. p - aminodiphenyl ether, in the last stage of the condensation. This subject-matter does not appear in the Specification as accepted. N - Methyl - a - phenyl - and - a - methylindolesulphonic acids are obtainable by sulphonating the corresponding indoles with fuming sulphuric acid, the sulphonic group probably entering the 6-position.