One-pot cascade reactions catalyzed by acid–base mesoporous MCM-41 materials

Abstract

Acid–base bifunctional mesoporous materials (AB-MCM-41) with aminopropyl and propanesulfonic acid in the same mesoporous material have been synthesized by two different methods: postsynthetic grafting and direct synthesis. AB-MCM-41-g was gained by the modification of SO3H-MCM-41 surfaces with organic amine functional groups, while AB-MCM-41-co was prepared through co-condensation of trialkoxyorganosilanes with tetraethyl orthosilicate. The bifunctional samples possess hexagonal arrays of uniform pores, large surface area, high pore volume and excellent acid–basic properties. One-pot acid–base cascade reactions were wonderfully achieved in the presence of the efficient acid–base catalysts, which demonstrate the coexistence of acid and base sites in the same material. In addition, the AB-MCM-41-g possesses higher activity for one-pot deacetalization–Knoevenagel and deacetalization–nitroaldol (Henry) reactions in contrast to AB-MCM41-co and this outcome is achieved under simpler synthetic conditions utilizing less time and less material.