GB659810A - Improvements in or relating to the production of benzene hexachloride - Google Patents

Abstract

Benzene hexachloride enriched in g -isomer is prepared by chlorinating benzene below 40 DEG C. with actinic irradiation, stopping the chlorination when 10-60 per cent, preferably 25-50 per cent, by volume of the benzene has been converted, removing the separated solid phase, and recovering the g -enriched product from the solution without further chlorination. It is preferred to correlate the temperature of the separation step with the extent of chlorination, i.e. when it is 50 per cent or less, the separation temperature is not higher than 40 DEG C., when it is more than 50 per cent the separation temperature is 40-80 DEG C., and when it is 40 per cent or less the temperature used is about 25 DEG C. Liquid chlorine may be used. It is preferred to use agitation during chlorination and to remove excess chlorine, e.g. by air-blowing, from the solution. The g -enriched product may be chilled at 0-5 DEG C. to crystallize it in part. An example is given of the process in which 50 per cent of the benzene is chlorinated and the separation temperature is 20 DEG C. The Specification as open to inspection under Sect. 91 comprises also the subject-matter of Specification 656,457. This subject-matter does not appear in the Specification as accepted.ALSO:A benzine hexachloride rich in the g -isomer (prepared by the chlorination of benzene to an extent of 10-60 per cent, removal of precipitated g - and b -isomers, and recovery of the g -isomer from the residual solution) is used as an insecticide; it may be mixed with a carrier such as clay or pyrophyllite, made into a spray by dissolving in e.g. toluene, xylene or methylnaphthalene, or emulsified in a xylene solution with water in the presence of, for example, alkylphenoxy polyethoxy ethanol. The enriched product employed as above contains at least 20-30 per cent and possibly as much as 90 per cent of the g -isomer. Specification 656,457 is referred to.