Thiol Functionalized Cross-Linked Chitosan Polymer Supporting Palladium for Oxidative Heck Reaction and Reduction of p-Nitrophenol

A novel porous cross-linked chitosan polymer was prepared by Schiff reaction of chitosan (CS) with terephthalic aldehyde (TPA), followed by modification with trimethoxysilylpropanethiol. Such functional CS polymer (CS-TPA) could serve as both support and stabilizer for homogeneous palladium (Pd2+) catalyst. The obtained heterogeneous catalyst (Pd/CS-TPA-SH) exhibited high catalytic activity and selectivity for the oxidative Heck reaction of benzene and ethyl acrylate. The excellent performance is mostly attributed to the -SH groups stabilized Pd2+ species. Furthermore, Pd/CS-TPA-SH can also be used as the catalyst for the reduction of p-nitrophenol at room temperature, showing high efficiency and steady reusability. A novel thiol functionalized cross-linked chitosan polymer supporting palladium is synthesized and proved to be a highly efficient catalyst for oxidative Heck reaction and nitrophenol reduction.