Novel Brønsted acidic ionic liquids based on benzimidazolium cation: Synthesis and catalyzed acetalization of aromatic aldehydes with diols

In this article, a new group of Brønsted acidic task-specific ionic liquids based on benzimidazolium cation was synthesized and used as environmentally benign catalysts for acetalization of aromatic aldehydes with diols. Hammett method had been used to determine the acidity order of these ionic liquids, which was consistent with the catalytic activities observed in acetalization reaction. Maximum substrate conversion of 98% and product selectivity of 100% were obtained using [PSebim]HSO₄ as catalyst, which could be reused at least 10 times without obvious loss of catalytic activity.