GB659824A - Production of benzene hexachloride - Google Patents

Abstract

Benzene hexachloride enriched in g -isomer is prepared by treating liquid benzene with chlorine in presence of actinic light at a temperature in the range 15-40 DEG C., discontinuing the chlorination after 20-50 per cent by volume of the benzene has been converted to benzene hexachloride, separating solid phase material from the solution at a temperature which is correlated with the extent of chlorination, and then recovering the g -isomer enriched product from the solution without further chlorination. When the extent of chlorination is 20 per cent the separation temperature used is 0 DEG \sB 10 DEG C., when the extent is 50 per cent the separation temperature is 30 DEG \sB 10 DEG C., and these two conditions should be maintained in a linear relationship for intermediate values. In the examples: (1) the extent of chlorination was 43-45 per cent and the separation temperature about 25 DEG C.; (2) the extent was 20 per cent and the separation temperature 0 DEG C.; the chlorination temperature in both cases was just below 40 DEG C. The Specification as open to inspection under Sect. 91 comprises a process in which an inert solvent may be present in the reaction and in which higher separation temperatures and lower chlorination temperatures may be employed. An example is given of the process employing acetic acid as solvent. This subject-matter does not appear in the Specification as accepted.