Partial Hydrogenation of 1,3-Cyclooctadiene Catalyzed by Palladium Complex Catalysts Immobilized on Silica

摘要

Homogeneous reaction systems have advantages over their respective heterogeneous counterparts in attaining high activity and selectivity by virtue of concentrating and intimate-contacting between the catalyst and the reactant(s); however, some significant shortcomings are experienced in the homogeneous reaction systems such as the recovery of catalyst and the separation of substrate and product. The problematic separation of homogeneous catalysts from reaction products in solution has hampered the commercialization of a number of excellent homogeneous catalysts. Furthermore, complex ligands and homogeneous metal catalysts have become increasingly expensive. Therefore, it is natural that besides the efforts to design effective catalysts, bridging the gap between homogeneous and heterogeneous catalyses by the variation of application phase, i.e., "heterogenized", "immobilized", or "anchored" catalysis, has been another subject of intensive research on homogeneous catalysis ever since its beginning. In this regard, we have prepared palladium complexes immobilized on silica and applied the resulting catalysts to the partial hydrogenation of 1, 3-cyclooctadiene.