Effect of Lewis acidity and polarizability of imidazole-based chloroaluminate ionic liquids on the catalytic performance for the alkylation of benzene

A series of imidazole-based chloroaluminate ionic liquids with different alkyl and halogen substituents were prepared and characterized to investigate molecular structure, Lewis acidity, and polarizability of ionic liquids, which were correlated with their catalytic performance in benzene alkylation. [Bmim]⁺ Al₂Cl₆Br^- had proper Lewis acidity strength and polarizability, and best catalytic activity in benzene alkylation among all imidazole-based chloroaluminate ionic liquids. Conversion of 1-dodecene 93.2% with 2-dodecylbenzene selectivity 37.7% was obtained when n([Bmim]⁺ Al₂Cl₆Br^-)/n(1-dodecene) was 0.005.