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.