GB347234A - Improvements in the manufacture and production of vat dyestuffs containing halogens - Google Patents

Abstract

Halogenated dibenzanthrones and isodibenzanthrones or their derivatives, other than iodo derivatives, are treated with a halogen different from that contained in the initial material, or an agent supplying such halogen, in an organic solvent or diluent and preferably in the presence of a catalyst, to yield chlorobromo derivatives containing at least one atomic proportion of each of the halogens. Such chlorobromo derivatives may also be obtained by treating dibenzanthrones or isodibenzanthrones or derivatives thereof, other than iodo derivatives, simultaneously or successively with chlorine and bromine or agents supplying such halogens, in an organic solvent or diluent and preferably in the presence of a halogenating catalyst. Suitable diluents are nitrobenzene, trichlorbenzene, dichlorbenzene, acetic anhydride and quinoline. The initial halogenated materials may be prepared as described in Specifications 325,525 and 329,263, [both in Class 2 (iii), Dyes &c.]. The halogen introduced may in part replace halogen in the starting material or replace other substituents such as nitro or sulpho groups. In examples is described the production of chlorobromo derivatives from dibenzanthrone, isodibenzanthrone, dibromodibenzanthrone (prepared by bromination in chlorsulphonic acid in the presence of antimony or iron), tribromdibenzanthrone (prepared by bromination in chlorsulphonic acid in presence of antimony), nitrodibenzanthrone (prepared by nitrating in nitrobenzene at 0-20 DEG C.) and dichlorisodibenzanthrone (example 1 or 2 of Specification 7931/09, [Class 2 (iii), Dyes &c.]). These products dye blue to violet shades and are characterized by being insensitive to temperature in the dyeing process. Specification 284,656, [Class 2 (iii), Dyes &c.], also is referred to.