Temperature-controlled highly selective dimerization of α-methylstyrene catalyzed by Bronsted acidic ionic liquid under solvent-free conditions

A temperature-control led highly selective dimerization of a-methylstyrene to produce 2,4-diphenyl-4-methyl-1-pentene and 1,1,3-trimethyl-3-phenylindan was catalyzed by Bronsted acidic ionic liquid [Hmim]+BF4-. At 60 degrees C, 2,4-diphenyl-4-methyl-1-pentene was formed in 93% selectivity with > 92% conversion under a solvent-free condition while 1, 1,3-trimethyl-3-phenylindan could be obtained in 100% selectivity when the reaction temperature was increased to 170 degrees C. The ionic liquid [Hmim]+BF4- could be reused with almost no loss of activity. (c) 2006 Elsevier Ltd. All rights reserved.