Synthesis, characterization, and application of poly(4-vinylpyridinium butane sulfonic acid) hydrogen sulfate as a novel poly(ionic liquid) and heterogeneous solid acid catalyst for the preparation of 1,8-dioxo-octahydroxanthenes

Poly(4-vinylpyridinium butane sulfonic acid) hydrogen sulfate, P(4VPBSA)HSO4, a novel polymeric acidic catalyst, was easily prepared by reaction of cross-linked poly(4-vinylpyridine) with 1,4-butane sultone and further acidification of the catalyst with sulfuric acid. The catalyst was studied by FT-IR spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The poly(ionic liquid) catalyst was shown to be an efficient dual acidic catalyst for one-pot preparation of 1,8-dioxo-octahydroxanthenes under solvent-free conditions. Reusability of the catalyst, easy work-up, eco-friendly reaction conditions, short reaction times, and high yields are some advantages of this procedure.