Recycable Ligand-Free Mesoporous Pd Catalysts for Heck Reaction

Significance

Ligand-free Pd-MCM-41 catalysts were found to work as a highly efficient and recyclable catalyst for the Heck reaction. The catalysts exhibited unprecedented stability among heterogeneous catalysts and can be reused at least 20 times to achieve complete conversion. Thus, new heterogeneous palladium catalysts supported on MCM-41 were prepared from tetraethoxysilane, cetyltrimethylammonium bromide, NH₃, and water containing appropriate amounts of PdCl₂. All three catalysts showed high activity and selectivity in the Heck reaction of iodobenzene with methyl acrylate (89-100% yields, 100% E selectivity). The 1.39% Pd-MCM-41 catalyst exhibited the highest activity (100% yield). The catalyst was readily recovered by filtration and reused 20 times without any loss of activity (100% yields for 20 times).