Brønsted acidic ionic liquids as novel catalysts for Prins reaction

Prins reaction, used to prepare dioxanes, has been limited by complex catalyst separation and reusability. In this article, six water-stable Brønsted acidic task-specific ionic liquids ([HMIM]BF4,[(CH2)4SO3HMIM][HSO4], [(Ac)2BIM]Br, [NMP][HSO4], [BMIM][HSO4] and [BMIM][H2PO4] were synthesized and used as environmentally benign catalysts for Prins reaction under mild reaction conditions for the first time. The process is highly effective and environmentally benign. Furthermore, [BMIM][HSO4] was conveniently separated with the products and easily recycled to catalyze Prins reaction again with excellent yields.