GB394990A - Manufacture of halogen derivatives of the benzophenone and anthraquinone series - Google Patents

Abstract

Benzophenone and anthraquinone derivatives.--A halogenmethylbenzophenone of the formula <FORM:0394990/IV/1> wherein R stands for a residue of the benzene series which may be substituted, but is unsubstituted in one o-position to the CO-group, is reacted with halogen under conditions such that the methyl hydrogen atoms are completely or nearly completely exchanged for halogen atoms, and the product is subjected to the action of a saponifying and ring-closing agent, so as to form the corresponding halogenanthraquinone-carboxylic acid or aldehyde. By treating the halogenated products with an agent having a saponifying action only, such as caustic soda, halogenbenzophenone-carboxylic acid or aldehyde derivatives are obtained, and these may then be subjected to the action of a ring-closing agent to yield the corresponding anthraquinone derivatives. Advantageous halogenation conditions comprise the presence of an indifferent diluent, such as trichlorobenzene, whilst exposing the mixture to the light of a mercury vapour lamp. In examples: (1) 2 : 5-dimethyl-4-chlorbenzophenone (prepared by condensing 1 : 4-dimethyl-3-chlorobenzene with benzoyl chloride) is chlorinated in trichlorbenzene at 170-180 DEG C. whilst exposing to ultra-violet to give a o -hexachloro derivative; treating this product with concentrated sulphuric acid yields 2-chloranthraquinone-3-carboxylic acid, whereas by using caustic soda 4-chlorbenzophenone-3 : 6-dicarboxylic acid is first obtained and this can then be ring-closed as above; the chlorination process can be interrupted when the o -pentachloro derivative is formed, and this, on ring-closing by means of sulphuric acid, yields a mixture of 2-chloranthraquinone-3-carboxylic acid and aldehyde which are separated by adding sodium carbonate; (2) 2 : 5 : 4<1>-trimethyl-4 : 5<1>-dichlorobenzophenone (prepared by condensing 2-chloro-p-xylene with 3-chloro-4-methylbenzoic acid chloride) is chlorinated as in (1) and the product treated with concentrated sulphuric acid to give 2 : 6-dichloroanthraquinone-3 : 7-dicarboxylic acid; the 2 : 7-dichloranthraquinone-3 : 6-dicarboxylic acid is similarly prepared from 2 : 5 : 5<1>-trimethyl-4 : 4<1>-dichlorbenzophenone. Specification 10790/13 (as open to inspection under Sect. 91), [Class 2 (iii), Dyes &c.], is referred to.