Fiber-Supported Acid–Base Bifunctional Catalysts for Efficient Nucleophilic Addition in Water

Abstract

A series of fiber supported acid–base bifunctional catalysts (FABCs) were developed by successive grafting of acrylic acid and 4-vinylpyridine onto the polypropylene fiber (PPF). The FABCs can efficiently catalyze a number of reactions whose key steps involve in nucleophilic addition. The obviously enhanced activities of the bifunctional catalysts compared with that of the individual fiber supported acid or base upon the nitro-aldol and Knoevenagel reactions indicate that the FABCs perform in a cooperative catalyzing model and their activities can be easily tuned by controlling the acid–base ratio. An optimized bifunctional catalyst was successfully applied to the aqueous Gewald, tandem Michael–Henry reaction and one three-component reaction with excellent catalytic performances. In addition, this newly developed bifunctional fiber catalyst also exhibits excellent recyclability and reusability with simple treatment.