Mesoporous systems, sulfonated

A wide variety of solid-acid catalysts is available [17] acidic clays, zeolites, silica-occluded heteropoly acids, sulfonated polysiloxanes, Nafion (a sulfonated perfluoroalkyl resin) and Nafion-silica composites, and a variety of hybrid sulfonated mesoporous systems (see Chapter 3). [Pg.6]

Mesoporous silicas modified with acidic groups [e.g. grafted alkyl or aryl sulfonic acids, or containing heteropolyacids or sulfated zirconia within their large pores) have generally provided higher yields, with several systems achieving over 70% yield. Amberlyst resins have been used in these reaction with some success, and the best systems (75% and 100% yield) both required DMSO as solvent, attributed to its ability to remove water and minimise decomposition reactions of the products. ... [Pg.75]