Direct synthesis of acid-base bifunctionalized hexagonal mesoporous silica and its catalytic activity in cascade reactions

A series of efficient acid-base bifunctionalized hexagonal mesoporous silica (HMS) catalysts contained aminopropyl and propanesulfonic acid have been synthesized through a simple co-condensation by protection of amino group. The results of small-angle XRD, TEM, and N-2 adsorption-desorption measurements show that the resultant materials have mesoscopic structures. X-ray photoelectron spectroscopies, elemental analysis (EA), back titration, Si-29 NMR and C-13 NMR confirm that the organosiloxanes were condensed as a part of the silica framework. The resultant catalysts exhibit excellent acid-basic properties, which make them possess high activity for one-pot deacetalization-Knoevenagel and deacetalization-nitroaldol (Henry) reactions. (C) 2010 Elsevier Inc. All rights reserved.