Sulfonic acid functionalized hyperbranched poly(ether sulfone) as a solid acid catalyst

Abstract

Sulfonic acid functionalized hyperbranched poly(ether sulfone) (SHBPES) was studied as a novel type of solid acid catalyst. Various molecular weights of SHBPESs were tested for the esterification reaction between acetic acid and 1-butanol. The SO₃H terminal groups of the SHBPESs work as catalytically active sites, but all tested SHBPESs are totally or partially soluble under the current reaction conditions. To overcome the solubility problem, SHBPES was grafted onto carbon black, and this material, SHBPES/CB, shows fairly good catalytic activity and promising recyclability. The turnover frequency of SHBPES decreased upon grafting it onto carbon black, but it was still much better than that of Amberlyst®-15. SHBPES/CB was also tested for the Friedel–Crafts alkylation of anisole and its durability seems to be much better than that of Amberlyst®-15 under the operating conditions at 130 °C.