GB716866A - Improvements in or relating to the preparation of chlorphenoxy compounds - Google Patents

Abstract

Chlorophenoxy acetonitriles are prepared by reacting a chlorophenoxymethyl monochloride with an alkali metal cyanide in a solvent medium comprising a ketonic solvent together with a minor proportion of water, optionally in the presence of a catalyst. The chlorophenoxymethyl mono-chlorides contain at least one chlorine atom but no other nuclear substituent, and are prepared by liquid-phase chlorination of compounds of formula R.OCH3, R being a benzene nucleus containing at least one chlorine atom, optionally in presence of a catalyst, e.g. phosphorus tri- and penta-chloride and sulphur mono-chloride. The alkaline hydrolysis or acid catalysed alcoholysis of 2 : 4-dichlorophenoxyacetonitrile yields 2 : 4-dichlorophenoxyacetic acid or its ester respectively. In examples: (1) Anisole is chlorinated using phosphorus pentachloride as catalyst to produce 2 : 4-dichlorophenoxy methyl monochloride, which with potassium cyanide in aqueous acetone yields 2 : 4-dichlorophenoxy acetonitrile. This on alkaline hydrolysis furnishes 2 : 4-dichlorophenoxyacetic acid together with bis-(2 : 4-dichlorophenoxy)-methane as by-product. (2) Example (1) is repeated, commencing with 2 : 4-dichloroanisole and employing sodium cyanide to form the nitrile. (3) 4-Chloro-anisole is chlorinated to yield 4-chlorophenoxymethyl monochloride which is converted to the corresponding nitrile as in (2). Specification 712,478 is referred to.