GB991299A - Preparation of chloro-substituted benzene derivatives - Google Patents

Abstract

Compounds of the general formula <FORM:0991299/C2/1> wherein X is hydrogen or chlorine; Y is a group -CCl3, -COOH, or -COCl; Z is hydrogen or a group -CCl3, -COOH, or -COCl, and is in m- or p-position with respect to Y, are obtained by reacting at 60-90 DEG C. a compound of the formula <FORM:0991299/C2/2> wherein X is hydrogen or chlorine and R is a hydrogen atom or a methyl group in m or p-position with respect to the methyl group, with chlorine in an inert medium under irradiation with U-V radiation or/and in presence of a free-radical generator type of catalyst to produce a compound of Formula I in which Y is a -CCl3 group and Z is H or -CCl3, and, if desired, subjecting the liquid obtained to hydrolysis to produce a compound of Formula I in which Y is a -COOH or -COCl group and Z is H or -COOH, or -COCl. The product formed by the chlorination process may be isolated by distillation. Partial hydrolysis to the acid chloride stage may be effected by adding water in an amount equivalent to the theoretical amount required together with a dehydrochlorinating catalyst such as FeCl3 or ZnCl2. For the production of compounds in which Y of the general formula is -COOH, hydrolysis is effected under acidic or alkaline conditions. If desired, the resulting solution from the chlorination reaction may be subjected to alcoholysis so as to obtain a corresponding ester. Compounds specified as starting materials are-o- and p-toluene sulphochloride, 3-chloro-4-methylbenzene sulphochloride, m- and p-xylene sulphochloride. Inert media specified are chloroform, carbon tetrachloride dichlorobenzene, tri-chloro-benzene, and chlorine substituted trichloromethyl or bis-trichloromethyl benzenes. Free radical generator type catalyst specified are azo-bis-isobutyronitrile; azo-bis-valeronitrile; lauroyl-, benzoyl-, 4-chlorobenzoyl-, and 2,4-dichlorobenzoyl peroxides. Examples describe the preparation of o- and p-chlorobenzotrichloride, 2,4-dichlorobenzotrichloride, 4 - chloro - 1,3 - bis - trichloromethyl - benzene, 2 - chloro - 1,4 - bis - trichloromethyl - benzene, p - chlorobenzoic acid, p - chlorobenzoyl chloride, 4 - chloro - isophthalic acid, and 2-chloro-terephthalic acid.