Transition metal ions supported on hydrogels as hydrogenation catalysts
TL;DR: In this article, the synthesis of new hydrogel polymers based on 2-hydroxyethyl methacrylate and other functional monomers is described, which are useful for anchoring palladium and rhodium species.
About: This article is published in Journal of Molecular Catalysis.The article was published on 1990-06-01. It has received 12 citations till now. The article focuses on the topics: Catalyst support & Catalysis.
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TL;DR: In this paper, a polymer-supported PBIMH was functionalized onto polystyrene beads crosslinked with 6.5 % divinylbenzene, and this solid support was then reacted with Na2PdCl4 in methanol.
Abstract: 2-(2′-Pyridyl)benzimidazole (PBIMH) was functionalized onto chloromethylated polystyrene beads crosslinked with 6.5 % divinylbenzene, and this solid support was then reacted with Na2PdCl4 in methanol. The functionalized beads were then activated using sodium borohydride. The resultant polymer-supported [2-(2′-pyridyl)benzimidazole]palladium complex (PSDVB–PBIM–PdCl2) and its activated form were characterized by various physicochemical techniques. XPS studies confirmed the +2 oxidation state of palladium in the supported complex. The activated complex was found to catalyse the hydrogenation of various organic substrates including olefins, nitro and Schiff base compounds. Kinetic measurements for the hydrogenation of cyclopentene, cyclohexene and cyclooctene were carried out by varying temperature, catalyst and substrate concentration. The energy and entropy of activation were evaluated from the kinetic data. The catalyst showed an excellent recycling efficiency over six cycles without leaching of metal from the polymer support, whereas the unsupported complex was unstable as metal leached out into the solution during the first run.
8 citations
TL;DR: In this article, a hydrogenation of 1-hexene, 1-heptene and 1-octene was carried out using anchored montmorillonitebipyridinepalladium(II) acetate (CII) and montmorillonsitebiphiphosphinopalladium (II) chloride (CIII) in THF under the reaction conditions 100% saturation of the carbon-carbon double bond.
Abstract: Hydrogenation of 1-hexene, 1-heptene and 1-octene was carried out using anchored montmorillonitebipyridinepalladium(II) acetate (CI), montmorillonitebipyridinepalladium(II) chloride (CII) and montmorillonitediphenylphosphinopalladium(II) chloride (CIII) in THF Under the reaction conditions 100% saturation of the carbon–carbon double bond was observed The observed rates were first order with respect to the partial pressure of hydrogen and fractional order with respect to [substrate] and [catalyst] The hydrogenation rates were found to be: 1-hexene > 1-heptene > 1-octene for all three catalysts The reactivity order of various catalysts is: CI > CII > CIII Thermodynamic and activation parameters were evaluated A rate law and a plausible mechanism has been proposed
8 citations
TL;DR: In this article, the synthesis and characterisation of copolymers containing tertiary nitrogen to which Cu(I) or Cu(II) species are anchored is described, and the anchored species function as catalysts for the oxidation of 2,6-xylenol by O 2 under basic conditions.
7 citations
TL;DR: In this paper, a polymer-anchored rhodium complex was synthesized by sequential attachment of benzimidazole (BzlH) and RhCl3 to chloromethylated poly(styrene-divinylbenzene) co-polymer (PSDVB) with 6.5% cross-linking.
Abstract: A polymer-anchored rhodium complex was synthesised by sequential attachment of benzimidazole (BzlH) and RhCl3 to chloromethylated poly(styrene–divinylbenzene) co-polymer (PSDVB) with 6.5% cross-linking. The catalyst was characterised by X-ray photoelectron spectroscopy, far-IR, UV–Vis, FTIR, SEM and thermogravimetric analysis. Various physico-chemical properties such as bulk density, surface area and swelling behaviour in different solvents were also studied. The polymer-anchored complex was tested as a catalyst for reduction of nitroarenes, namely o,m,p-nitrobenzoic acid, nitroaniline, nitrophenol and nitrotoluene. Kinetic measurements were carried for o-nitroaniline and p-nitrophenol by varying temperature, catalyst concentration and concentration of substrates. The rate of the reaction was found to be first order with respect to catalyst concentration and also with substrate concentration at low concentrations, becoming independent of substrate at higher concentrations. A plausible mechanism for the reaction is proposed. The energy and entropy of activation calculated from Arrhenius plots indicate high activity of the catalyst on the support. The recycling efficiency of the catalyst has been studied and there was no leaching of metal from the catalyst surface.
3 citations
TL;DR: A polymer-supported palladium-2-methylimidazole complex was synthesized and characterized by various physicochem methods as mentioned in this paper, which was successfully used as a catalyst for the hydrogenation of nitrobenzene and its derivs.
Abstract: A polymer-supported palladium-2-methylimidazole complex was synthesized and characterized by various physicochem. methods. The complex was successfully used as a catalyst for the hydrogenation of nitrobenzene and its derivs. under ambient conditions. Results reveal that the electronic as well as the steric effects of the substituent control the rate of hydrogenation of the nitro group in the studied nitro compds. The kinetics of hydrogenation and the reusability of the catalyst were also studied.
2 citations
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74 citations
TL;DR: In this paper, a polymer-bound palladium (II) chloride complex has been prepared by the reaction of palladium chloride with a phosphinated polystyrene, and the rates of hydrogenation of cyclohexene, styrene and 1,3-cyclooctadiene have been studied and the dependence on factors such as substrate concentration, catalyst concentration, pressure and temperature has been determined.
71 citations
TL;DR: Poly(styryl)bipyridine, 1, is produced from the reaction of lithiated polystyrene with bipyridine in tetrahydrofuran as discussed by the authors.
Abstract: Poly(styryl)bipyridine, 1, is produced from the reaction of lithiated polystyrene with bipyridine in tetrahydrofuran. Under our conditions, bipyridine becomes bound to 1615% of the phenyl residues. The reaction of 1 with a variety of transition-metal salts can be carried out in a variety of swelling solvents and results in formation of polymer-bound bipyridine transition-metal complexes. The extent of metal incorporation depends on solvent, metal ion concentration, and the identity of the metal species. Zerovalent metal complexes such as@-Ph-bpy-M(CO), (M = Cr, Mo, W) are readily prepared from the reaction of 1 with the metal hexacarbonyl complexes. (Poly(styry1)bipyridyl)palladium acetate is an active catalyst for the hydrogenation of olefins at ambient pressure and temperature. It can also be used to catalyze the acetoxylation of benzene; however, the percent conversion in this case is rather low.
49 citations
TL;DR: In this article, the authors studied the hydrogenation of 15 acetylenes to olefins catalyzed by polymer-bound palladium(II) complexes synthetically and mechanistically.
32 citations