A Liquid−Liquid Process for Production of 2,4-Diphenyl-4-methyl-1-pentene by Dimerization of α-Methylstyrene

A liquid−liquid process for the dimerization of α-methylstyrene (AMS) in order to produce selectively the commercially useful 2,4-diphenyl-4-methyl-1-pentene has been developed. The aqueous phase contained sulfuric acid as a catalyst and methanol as an additive, and the organic phase was 97% α-methylstyrene (AMS). An AMS conversion of 55% was achieved in 7 h when the dimerization was conducted at 80 °C. The product dimer contained 93% 2,4-diphenyl-4-methyl-1-pentene and only 0.06% 1,1,3-trimethyl-3-phenylindan, the saturated dimer. The liquid−liquid process can be used commercially to produce selectively 2,4-diphenyl-4-methyl-1-pentene at locations where cation-exchange resins are not readily available.