SBA-15-supported poly(4-styrenesulfonyl(perfluorobutylsulfonyl)imide) as heterogeneous Brønsted acid catalyst for synthesis of diindolylmethane derivatives

Abstract

By means of immobilizing the acidic homopolymer, poly(4-styrenesulfonyl(perfluorobutylsulfonyl)imide) (PSFSI), onto SBA-15 silica, a new type of strongly acidic composite catalyst was developed. The properties of the catalyst were characterized by NMR, FT-IR, XRD, SEM, TEM, XPS, TG, and GPC. The solid acid catalyst was highly effective and could be recycled at least five times without obvious loss of activity for the condensation of indole with structurally diverse aldehydes, which yielded diindolylmethane derivatives (DIMs).