Ying Wan
Shanghai Normal University, China
Title: Reusable mesoporous solid-based Pd catalysts for chlorobenzene suzuki coupling reaction and selective indoles C2-arylation in water
Biography
Biography: Ying Wan
Abstract
Environmentally benign, operationally simple, and robust reactions, particularly those employing reusable solid catalysts and water as a solvent, are of significant interest to the chemical industry. Here, heterogeneous palladium catalysts supported on ordered mesoporous carbonaceous nanocomposites including carbon-silica , CoO-C and quaternary ammonium phase transfer agent modified mesoporous carbonaceous resins, were applied to the water-mediated Suzuki coupling reaction using as the substrate, and selective C2-Arylation of indoles. The mesoporous Pd/CoO-C catalyst showed a high yield of biphenyl (49%) in the water-mediated Suzuki coupling reaction of chlorobenzene and phenylboronic acid. Product yields in the reaction of aryl chlorides containing electron-withdrawing groups attached to their benzene ring can reach approximately 90%. Very small Pd clusters consisting of approximately 3 atoms and Pd-O bonds formed on the interface between CoO and Pd nanoparticles. The unsaturated coordinative Pd may be responsible for the activation of chlorobenzene in the absence of any additives or ligands. A nitrogen-containing functional group modified and ordered mesoporous resin material was also used to support a reusable solid Pd catalyst. The grafted quaternary N coordination with highly dispersed Pd NPs creates an electronically rich environment for surface atoms and causes a distinct enhancement in the stabilization and accessibility of these particles to organic substances in aqueous solution. The mesoporous Pd catalysts are active in the C-2 arylation of N-methylindole when water is used as the solvent without any other additive or the exclusion of air. The catalysis likely occurs on the Pd surface rather than in solution.