Improvements in or relating to preparation of m- and p-diisopropylbenzene

摘要

A diisopropylbenzene substantially free from o-diisopropylbenzene and trimethylindene is obtained by propylating benzene in an alkylation reaction with a propylene-containing gas containing no higher weight unsaturates, in the presence of a Friedel-Craft condensation catalyst to a mixture rich in polyisopropylbenzene, separating the polyisopropylbenzenes from the benzene, cumene, and diisopropylbenzenes, contacting the polyisopropylbenzenes in admixture with benzene with 0.1 to 2.0 mol. per cent of the disproportionation reaction mixture of aluminium chloride at a temperature in the range of 65-115 DEG C. until the mixture is enriched in m-diisopropyl benzene and is substantially free from o-diisopropylbenzene and trimethylindane, and separating the m-diisopropylbenzene by distillation. The initial alkylation may be catalysed at 50-80 DEG C. with 80 per cent sulphuric acid or at temperatures from 50-115 DEG C. with aluminium chloride. In the disproportionation step the aluminium chloride powder is mixed with the benzene and polyisopropylbenzene at a temperature of 10 DEG C. and the temperature is slowly raised to 115 DEG C. Specifications 763,179 and 763,180 are referred to.