Synthesis and application of modified polystyrene-supported palladium nanoparticles as a new heterogeneous catalyst for Heck and Suzuki cross-coupling reactions

A new nitrogen-containing phosphinite ligand based on modified Merrifield resin was synthesized and characterized. This ligand was combined with PdCl2 to afford efficient catalyst for Heck and Suzuki cross-coupling reactions. The catalyst was highly efficient for cross-coupling reactions of aryl iodides, bromides and also chlorides with olefinic compounds. Aryl chlorides are usually inactive in coupling reactions, but with this catalytic system, excellent result was gained in the presence of tetrabutylammonium bromide. Transmission electron microscopy of catalyst shows that palladium was well dispersed and of typical diameter of 8–30 nm. The X-ray powder diffraction pattern of the Pd catalyst was consistent with the metallic Pd (0). Elemental analysis of Pd by ICP-OES and hot filtration test shows low leaching of the metal into solution from the supported catalyst which confirms the full heterogeneous character of the catalytically active species. Short reaction times, excellent yields and recyclability are among the advantages of this polymeric catalytic system. The catalyst can be reused for many times without loss in its efficiency.