Polymer-bound Palladium Complexes Research Articles

The first insoluble polymer-bound palladium complexes of 2-pyridyldiphenylphosphine: highly efficient catalysts for the alkoxycarbonylation of terminal alkynes

Palladium complexes of 2-pyridyldiphenylphosphine anchored on polystyrene, polymethylmethacrylate and styrene-methylmethacrylate copolymer form highly active heterogeneous catalysts for the alkoxycarbonylation of terminal alkynes with activities approaching those obtained under homogeneous conditions.

The Cross-Coupling Reaction of Arylboronic Acids with Chloropyridines and Electron-Deficient Chloroarenes Catalyzed by a Polymer-Bound Palladium Complex

The cross-coupling reaction of tolylboronic acids (1.3 equiv.) with chloropyridines, chloroquinoline, or activated chloroarenes having an electron-withdrawing group was carried out in toluene at 80°C in the presence of a polymer-bound PdCl 2 catalyst (3 mol%) and aqueous 2 M K 3PO 4 (2.6 equiv.). The palladium–phosphine complex supported on a polystyrene–PPh 2 resin was reused with no significant decrease in activity.

1,3-butadiene telomerization with methanol catalyzed by heterogenized palladium complexes

The heterogenization of palladium complexes on silica as well as on functionalized styrene/divinylbenzene crosslinked resins and linear poly(styrene) is described. In particular, palladium (0) and palladium (II) derivatives were anchored to the above polymeric systems through their functionalization with bidentate ligands such as acetylacetonate and 1,3-bis(diphenylphosphino)propane moieties. The resulting heterogenized complexes were checked in the catalytic telomerization of 1,3-butadiene with methanol. Their performances were studied in terms of activity and selectivity to telomers. Whereas the heterogenization of palladium complexes either on silica or on polymer resins via the acetylacetonate ligand resulted labile during the catalytic cycle, the polymer-bound palladium complexes via the diphosphine ligand, when activated by an alkoxide, displayed activity and selectivity comparable with those of the corresponding homogeneous counterparts, without appreciable metal leaching in solution.

Synthesis of 1-Nonene from Decanoic Acid by Polymer-Bound Palladium Complexes

Abstract (phCN)2PdCl2 or Pd(OAc)2 was immobilized on polyorganosiloxane bearing phosphine group as the support. The catalytic activity of polymer-bound palladium complex revealed higher activity and selectivity than the homogeneous catalyst for the synthesis of 1-nonene from decanoic acid.

Hydrogenation of olefins catalyzed by polymer-bound palladium complexes of different valence states

A special catalyst with palladium in two different valence states was prepared by refluxing 8-aminoquinoline resin-bound palladium(II) complexes —Pd(OAc) 2, PdI 2, PdCl 2 or Pd(acac) 2—in an methanol-water solution (pH = 12). Hydrogenation of hexene (20 mmol) with 0.0135 meq (based on Pd) of catalyst at 40°C under atmospheric hydrogen pressure and the selective hydrogenation of 1,5,9-cyclododecatriene (CDT) with 0.0789 meq (based on Pd) of catalyst at 100°C under 20 kg/CM 2 hydrogen pressure were studied. The hydrogenation rate of hexene was correlated with the Pd particle size on the support surface. No loss of Pd was observed in this reaction. The effects of the electron donor constant, E n, of the Pd complex ligand and the Pd particle size on the catalytic activity and selectivity in the hydrogenation of CDT were examined. It was found that the loss of palladium decreased with an increase of Pd dispersed on the support surface and with a decrease in the polarity of the solvents.

Double Carbonylation of Organohalogen Compounds Catalyzed by Polymer-Bound Palladium Complexes

Abstract Palladium complex-catalyzed double carbonylation is a recently discovered reaction in organotransition metal chemistry. In this paper, some polymer-bound palladium complexes-polystyrylphosphine-palladium(0) complexes, poly-2-vinylpyridine-palladium(II) complexes, and poly-2-Af-vinylpyrrolidone-palladium(II) complexes have been prepared and characterized. The complexes were tested as catalysts in the double carbonylation reaction. Among these catalysts, polystyrylphos-phine-palladium(0) complexes showed good activity and selectivity, and can be easily recovered and reused. The influence of experimental parameters was investigated as well.

Selective hydrogenation of acetylenes to olefins catalyzed by polymer-bound palladium(II) complexes

Semihydrogenations of 15 acetylenes to olefins catalyzed by polymer-bound palladium(II) complexes have been studied synthetically and mechanistically, and the hydrogenation of phenylacetylene has been studied kinetically. In the hydrogenation of isolated acetylenes, the catalyst generated corresponding olefins in high selectivities (above 92%). In the case of conjugated acetylenes, the catalyst generated corresponding conjugated olefins in relatively low selectivities (71–85%), whereas phenylacetylene was hydrogenated to styrene in a high selectivity (93%). A high activity of the catalyst was observed in oxygen-containing solvents such as dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, and ethanol. The catalytic activity is affected more strongly by the π-acidity of acetylenes than their steric factor. The hydrogenation rate of phenylacetylene is expressed by the form: R = k 2[H 2][ A], where [H 2] and [ A] are hydrogen and the catalyst concentrations, respectively. A mechanism for the hydrogenation is proposed on the basis of kinetic studies. Finally, it is summarily discussed what factors control the activity and the selectivity of the polymer catalyst for the hydrogenation of carbon-carbon double and triple bonds. This polymer-bound palladium complex was shown to be comparable in selectivity to cationic rhodium and the Lindlar catalysts.