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Nickel Catalyst (nickel + catalyst)
Selected AbstractsChemInform Abstract: A Nickel Catalyst for the Addition of Organoboronate Esters to Ketones and Aldehydes.CHEMINFORM, Issue 8 2010Jean Bouffard Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Alkyl- or Arylthiolation of Aryl Iodide via Cleavage of the S,S Bond of Disulfide Compound by Nickel Catalyst and Zinc.CHEMINFORM, Issue 4 2005Nobukazu Taniguchi Abstract For Abstract see ChemInform Abstract in Full Text. [source] Stable Nickel Catalysts for Fast Norbornene Polymerization: Tuning ReactivityEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2005Juan A. Casares Abstract The air-stable complexes trans -[Ni(C6Cl2F3)2L2] (L = SbPh3, 1; AsPh3, 2; AsCyPh2, 3; AsMePh2, 4; PPh3, 5) have been synthesized by arylation of [NiBr2(dme)] (dme = 1,2-dimethoxyethane) in the presence of the corresponding ligand L (for compounds 1,4) or by ligand substitution starting from 1 (for compound 5). The structures of 1, 2, and 5 have been determined by X-ray diffraction and show an almost perfect square-planar geometry in all cases. Their catalytic activity in insertion polymerization of norbornene have been tested showing a strong dependence of the yield and molecular mass of the polymer on the ligand used and the solvent. High yield and high molecular mass values are obtained using complexes with ligands easy to displace from NiII (SbPh3 is the best) and noncoordinating solvents. Complexes 1,3 are suggested as convenient bench-catalysts to have available in the lab. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Preparation of sorbitol from D -glucose hydrogenation in gas,liquid,solid three-phase flow airlift loop reactorJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2004Jian-Ping Wen Abstract A new process for D -glucose hydrogenation in 50 wt% aqueous solution, into sorbitol in a 1.5 m3 gas,liquid,solid three-phase flow airlift loop reactor (ALR) over Raney Nickel catalysts has been developed. Five main factors affecting the reaction time and molar yield to sorbitol, including reaction temperature (TR), reaction pressure (PR), pH, hydrogen gas flowrate (Qg) and content of active hydrogen, were investigated and optimized. The average reaction time and molar yield were 70 min and 98.6% under the optimum operating conditions, respectively. The efficiencies of preparation of sorbitol between the gas,liquid,solid three-phase flow ALR and stirred tank reactor (STR) under the same operating conditions were compared. Copyright © 2004 Society of Chemical Industry [source] Modular Routes Towards New N,O-Bidentate Ligands Containing an Electronically Delocalised ,-Enaminone Chelating BackboneEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2008Udo Beckmann Abstract Polyketones are synthesised by a transition-metal-catalysed copolymerisation of olefins and carbon monoxide. Nickel complexes with N,O-chelating ligands turned out to be promising catalysts in that field. In this work a series of new N,O ligands with an electronically delocalised ,-enaminone backbone were synthesised and fully characterised. The ligand design was inspired by the ligand found in the most efficient nickel catalyst for polyketone synthesis and developed to a highly modular LEGO® -like arsenal of reactions to versatile substituted ,-enaminone ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] An Environmentally Benign, Highly Efficient Catalytic Reduction of p -Nitrophenol using a Nano-Sized Nickel Catalyst Supported on Silica-AluminaADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Islam Hamdy Abd El Maksod Abstract A green and effective method is reported for the reduction of p -nitrophenol to p -aminophenol using a nano-sized nickel catalyst supported on silica-alumina in the presence of hydrazine hydrate as an alternative source of hydrogen. It was found that nickel loaded on a silica-alumina support is a very effective catalyst in the hydrogenation of p -nitrophenol to p -aminophenol. Thus it attained 100% conversion in only 69 seconds instead of 260 seconds for commercial Raney nickel. In addition, the possibility to reuse it more than one time with great efficiency gives it another advantage over commercial Rainey nickel which cannot be used more than once. This economical and environmentally friendly method provides a potentially new approach for the synthesis of the intermediate product of paracetamol in industry, which overcomes the drawbacks of the known reduction methods. The prepared catalysts were fully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and electron spin resonance (ESR) tehniques. [source] Micron-granula polyolefin with self-immobilized nickel and iron diimine catalysts bearing one or two allyl groupsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2004Guoxin Jin Abstract Self-immobilized nickel and iron diimine catalysts bearing one or two allyl groups of [ArNC]2(C10H6)NiBr2 [Ar = 4-allyl-2,6-(i -Pr)2C6H2] (1), [ArNC(Me)][Ar,N C(Me)]C5H3NFeCl2 [Ar = Ar, = 4-allyl-2,6-(i -Pr)2C6H3, Ar = 2,6-(i -Pr)2C6H3, and Ar, = 4-allyl-2,6-(i -Pr)2C6H3] were synthesized and characterized. All three catalysts were investigated for olefin polymerization. As a result, these catalysts not only showed high activities as the catalyst free from the allyl group, such as [ArNC]2C10H6NiBr2 (Ar = 2,6-(i-Pr)2C6H2)], but also greatly improved the morphology of polymer particles to afford micron-granula polyolefin. The self-immobilization of catalysts, the formation mechanism of microspherical polymer, and the influence on the size of the particles are discussed. The molecular structure of self-immobilized nickel catalyst 1 was also characterized by crystallographic analysis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1018,1024, 2004 [source] Synthesis of polar vinyl monomer,olefin copolymers by ,-diimine nickel catalystPOLYMER INTERNATIONAL, Issue 5 2001Maria M Marques Abstract Vinyl acetate, methyl methacrylate, acrylonitrile and methyl vinyl ketone were investigated for co- and terpolymerization with ethylene and ethylene,propylene. Precursor [bis(N,N,,-dimesitylimino)acenaphthene]dibromonickel, activated by methylaluminoxane was used as a catalyst system and trialkylaluminium was employed to block the polar groups for these polymerizations. Polymerization activities of the order of magnitude of 106 in the case of vinyl acetate and methyl methacrylate, and 105 in the case of acrylonitrile were achieved. Microanalysis and GPC of acrylonitrile copolymers found about 17 units of acrylonitrile per polymer chain. Copolymers with very different properties from the parent homopolymers were obtained in all cases except that of methyl vinyl ketone. © 2001 Society of Chemical Industry [source] Biphasic oligomerization of ethylene with nickel complexes immobilized in organochloroaluminate ionic liquidsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 11 2009Lixia Pei Abstract Ethylene was selectively oligomerized by nickel complexes such as (PPh3)2NiBr2 and (PPh3)2NiCl2 immobilized in chloroaluminate ionic liquid in biphasic catalytic reactions. The influence of reaction parameters such as reaction media, reaction temperature and Et2AlCl:Ni molar ratio was also evaluated. Turnover frequency up to 24000 mol C2H4/(mol Ni h) was achieved under mild reaction conditions (0.5 atm and 40 °C). GC-MS analyses showed that the obtained oligomers completely consist of C4 and C6. The olefinic products can be easily separated from the catalytic ionic liquid phase by simple decantation, and the nickel catalyst can be reused without a significant decrease in turnover frequency and change of the distribution of the olefinic products. Copyright © 2009 John Wiley & Sons, Ltd. [source] Novel nickel-based catalyst for low temperature hydrogen production from methane steam reforming in membrane reformerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Yazhong Chen Abstract Hydrogen production from various hydrocarbon fuels, particularly biomass-derived fuels, has attracted worldwide attention due to its potential for application to fuel cells, a device which converts chemical energy into electricity efficiently and cleanly. However, current technology, such as natural gas steam reforming, could not meet the specific requirements of hydrogen for fuel cells. Therefore, novel processes are intensively investigated, aiming to develop economic and efficient ones for the specific purpose. An important direction is the integrated membrane reformer for one-step high-purity hydrogen production. However, for the commercial realization of this technology, there are still some difficulties to overcome. By comparison with previous investigations with a similar membrane, this work showed that catalyst also played an important role in determining membrane reformer performance. We proposed that when thickness of membrane was several micrometers, the permeance of membrane became less important than the kinetics of catalyst, due to the fact that under such conditions, hydrogen permeation rate was faster than the kinetics of steam reforming reaction when commercial catalyst was applied, but further evidence is indispensable. In this initial work, we focused on developing efficient nickel catalyst for low temperature steam reforming. Nickel-based catalyst was developed by deposition,coprecipitation and used as pre-reduced, showing high performance for methane steam reforming at low temperatures and good durability, which may find practical application for the integrated membrane reforming process. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] The Combined Catalytic Action of Solid Acids with Nickel for the Transformation of Polypropylene into Carbon Nanotubes by PyrolysisCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2007Rongjun Song Abstract The effects of both organically modified montmorillonite (OMMT) and Ni2O3 on the carbonization of polypropylene (PP) during pyrolysis were investigated. The results from TEM and Raman spectroscopy showed that the carbonized products of PP were mainly multiwalled carbon nanotubes (MWNTs). Surprisingly, a combination of OMMT and Ni2O3 led to high-yield formation of MWNTs. X-ray powder diffraction (XRD) and GC,MS were used to investigate the mechanism of this combination for the high-yield formation of MWNTs from PP. Brønsted acid sites were created in degraded OMMT layers by thermal decomposition of the modifiers. The resultant carbenium ions play an important role in the carbonization of PP and the formation of MWNTs. The degradation of PP was induced by the presence of carbenium ions to form predominantly products with lower carbon numbers that could be easily catalyzed by the nickel catalyst for the growth of MWNTs. Furthermore, carbenium ions are active intermediates that promote the growth of MWNTs from the degradation products with higher carbon numbers through hydride-transfer reactions. The XRD measurements showed that Ni2O3 was reduced into metallic nickel (Ni) in situ to afford the active sites for the growth of MWNTs. [source] Room Temperature Highly Enantioselective Nickel-Catalyzed HydrovinylationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Nicolas Lassauque Abstract At room temperature, nickel catalysts based on the new phosphoramidite (11bR)- N -[(S)-1-(naphthalen-1-yl)ethyl]- N -[(S)-1-(naphthalen-2-yl)ethyl]dinaphtho[2,1- d:1,,2,- f][1,3,2]dioxaphosphepin-4-amine provide excellent selectivities for 3-arylbut-1-enes (93,99%) with high enantioselectivities (90,95% ee) and TOFs (up to 8300,h,1) in the hydrovinylation of electron-rich and electron-poor vinylarenes. Within a few minutes, useful chiral building blocks and intermediates can be synthesized using this practical catalytic system. [source] | |||||||||||||||||||||||||