GB311661A - Manufacture of intermediate products of the benzanthrone series and dyestuffs therefrom - Google Patents

Abstract

311,661. Soc. of Chemical industry in Basle. May 12, 1928, [Convention date]. Benzanthrone derivatives. - Benzanthrone is oxidized with manganic sulphate in a sulphuric acid medium at a raised temperature using a proportion of oxidizing agent sufficient for the production of a dioxydibenzanthronyl; the product, which appears to be a dioxydibenzanthronyl, can be methylated, yielding a dimethoxy derivative, or converted into vat dyes by treating with alkaline condensing agents. By alkylating the dyes initially obtained, they can be converted into fast vat-dyes dyeing generally in grey to blue tints. In the examples : (1) benzanthrone is oxidized with manganic sulphate in sulphuric acid monohydrate at 60-65‹ C.; the product is freed from Bz 1: Bz1<1>-dibenzanthronyl, formed as a by-product, by crystallizing from nitrobenzene; (2) the product of example 1 is heated with alcoholic caustic alkali, the dyestuff formed dyes cotton in grey-blue tints which become dull blue-violet by the action of chlorine, (3) the product of example 1 is fused with caustic alkali, the resulting dyestuff dyes in grey-blue tints fast to chlorine, (4) the product of example 2 is methylated with p-toluenesulphonic acid methylester, the resulting dyestuff dyes cotton in grey tints fast to chlorine. An example of dyeing cotton with the dyestuff of example 4 is given. Specifications 251,313 and 278,112 are referred to. The Specification as open to inspection under Sect. 91 (3) (a) mentions also the halogenation of the dyestuffs obtained by treatment of the dioxydibenzanthronyl with alkaline condensing agents. This subject-matter does not appear in the Specification as accepted.