GB833218A - Preparation of 2, 3, 5, 6-tetrachlorobenzoyl halides and their derivatives, particularly for the production of herbicidal compositions - Google Patents

Abstract

2 : 3 : 5 : 6 - Tetrachlorobenzoyl halides such as the chloride and fluoride are prepared by chlorinating a benzoyl halide with chlorine in the presence of a chlorination catalyst at a temperature of 100 DEG to 230 DEG C. for a time sufficient to convert the reaction mixture at least partially into the desired product, and if desired, are converted into 2 : 3 : 5 : 6-tetrachlorobenzoic acid or a salt or ester thereof suitable by hydrolysis or reaction with an alcohol such as methanol or butanol. Suitable salts are obtained by reaction with inorganic or organic bases such as alkali or alkaline-earth metal oxides, hydroxides or carbonates, ammonia or amines such as mono-, di-or tri - alkylamines and alkanolamines. The products are used as herbicides (see Group VI).ALSO:Compositions for weed control, preventing germination, inhibiting normal growth and killing undesirable vegetation comprise as an active ingredient a 2 : 3 : 5 : 6-tetrachlorobenzyol halide such as the chloride or fluoride or a crude polychlorobenzoyl halide reaction product containing this compound, or a derivative of the halide which in the presence of water yeilds anions of 2 : 3 : 5 : 6-tetrachlorobenzoic acid, for example a salt or ester thereof (see Group IV(b)). Suitably the polychlorobenzoic acid or salt thereof such as an alkali-metal, alkaline earth metal, ammonium or amine e.g. alkylamine or alkanolamine salt, or the amide or ester is prepared in a liquid formulation in an organic solvent, optionally in the presence of a wetting or emulsifying agent, to give an emulsifiable system or in a solid or dust formulation with solid diluents, which may also contain wetting agents. Other herbicides may also be present.ALSO:Compositions for weed control, preventing germination, inhibiting growth and killing undesirable vegetation comprise as an active ingredient a 2 : 3 : 5 : 6-tetrachlorobenzoyl halide such as the chloride or fluoride or a crude polychlorobenzoyl halide reaction product containing this compound, or a derivative of the halide which in the presence of water yields anions of 2 : 3 : 5 : 6-tetrachlorobenzoic acid, for example a salt or ester thereof (see Group IV (b)). Suitably the polychlorobenzoic acid or halide, or salt thereof such as an alkali or alkaline-earth metal, ammonium or amine, e.g. alkylamine or alkanolamine, salt, or amide or ester is prepared in a liquid formulation in an organic solvent, optionally in the presence of a wetting or emulsifying agent to give an emulsifiable system or in a solid or dust formulation with solid diluents, which may also contain p wetting agents. Other herbicides may also be present.