GB763182A - Improvements in or relating to preparation of m- and p-diisopropylbenzene - Google Patents

Abstract

A diisopropylbenzene substantially free from o-diisopropylbenzene and trimethylindene is obtained by propylating benzene with a propylene-containing gas containing no higher molecular weight unsaturates in the presence of an acid-acting condensation catalyst to produce a reaction mixture rich in o-, m-, and p-diisopropyl benzene, and then contacting the mixture in an isomerization reaction with 0.1 to 2 mols. per cent of aluminium chloride at a temperature of 65-115 DEG C. until a mixture rich in m-diisopropylbenzene and substantially free from o-diisopropylbenzene and trimethylindane is obtained and separating it by distillation. p-Diisopropylbenzene may also be isolated by distillation. The initial alkylation reaction may be catalysed at 50-80 DEG C. with 80 per cent sulphuric acid, or up to 115 DEG C. when the catalyst is aluminium chloride. The isomerization step is effected by adding the aluminium chloride powder preferably at a temperature below 50 DEG C. and then allowing the temperature to rise gradually to 65-115 DEG C. After the reaction has been completed, the catalyst is removed by adding water, preferably containing acid or caustic. Specification 763,179 is referred to.