Silica-supported policresulen as a solid acid catalyst for organic reactions

A new type of solid catalyst was prepared by coating a thin layer of policresulen, an inexpensive polymer prepared via condensation of 2-hydroxy-4-methylbenzenesulfonic acid and formaldehyde that has been used as commercially available drug, onto the surface of silica. The policresulen component is insoluble in many organic solvents and can be adsorbed on silica with the aid of hydrogen bonding. The obtained silica/policresulen composite showed remarkable catalytic activity for various organic reactions. In model reactions, the catalyst can be recycled several times without significant loss of activity. The salient features of using this acid catalyst in organic reactions include cost-effectiveness, simple and time-efficient preparation, and the convenience of controlling the acid loading on the solid. (C) 2015, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.