Palladium Coordination Biopolymer: A Versatile Access to Highly Porous Dispersed Catalyst for Suzuki Reaction

This work describes a simple procedure to obtain hybrid materials based on palladium alginate acting as heterogeneous catalysts for the Suzuki carbon−carbon coupling reactions. When reacted with Na 2 PdCl 4, the carboxylate groups of alginate matrix act as chelating agent for Pd cations, which in turn behave as gelling agent of the support. During further steps of preparation, Pd cations spontaneously reduce to metallic species, and metal nanoparticles are obtained, homogeneously and highly dispersed in the biopolymer matrix. CO 2 supercritical drying leads to porous materials with surface area between 500 and 700 m 2 /g. Pure Pd samples show several unsatisfactory properties; mixed Pd, Ca exchanged samples have been therefore considered. These latter materials show high activity for the Suzuki carbon−carbon coupling reactions and the stability of the catalyst allows several reuses with only a slight loss of activity. The intimate contact between host and metal prevents any leaching of active species.