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Homogeneous Hydrogenation (homogeneous + hydrogenation)
Selected AbstractsHomogeneous Hydrogenation of Tri- and Tetrasubstituted Olefins: Comparison of Iridium-Phospinooxazoline [Ir-PHOX] Complexes and Crabtree Catalysts with Hexafluorophosphate (PF6) and Tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BArF) as CounterionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2008Bettina Wüstenberg Abstract Four iridium complexes with achiral phosphino-oxazoline (PHOX) ligands were readily prepared in two steps starting from commercially available phenyloxazolines. The air-stable complexes with tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BArF) as counterion showed high reactivity in the hydrogenation of a range of tri- and tetrasubstituted olefins. The best results were obtained with an iridium complex (11) derived from a dicyclohexylphosphino-oxazoline ligand bearing no additional substituents in the oxazoline ring. With several substrates, which gave only low conversion with the Crabtree catalyst, [Ir(Py)(PCy3)(COD)]PF6, full conversion was observed. The productivity of the Crabtree catalyst could be strongly increased by replacing the hexafluorophosphate anion with tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. In one case, in the hydrogenation of a tetraalkyl-substituted CC bond, [Ir(Py)(PCy3)(COD)]BArF gave higher conversion than catalyst 11. However, with several other substrates complex 11 proved to be superior. [source] Non-Metal-Mediated Homogeneous Hydrogenation of CO2 to CH3OH,ANGEWANDTE CHEMIE, Issue 52 2009Andrew Vom Schlechten zum Guten: CO2, das zur Erderwärmung beiträgt, wurde in den nützlichen Ausgangsstoff CH3OH überführt, indem es unter H2 (1,2,atm) zu 2,2,6,6-Tetramethylpiperidin und B(C6F5)3 in Toluol gegeben, die Mischung auf 160,°C erhitzt und im Vakuum destilliert wurde. CH3OH entstand als einziges C1 -Produkt über den gezeigten Komplex (C,blau, N,violett, O,rot, B,orange, F,grün). [source] The Synthesis of Amines by the Homogeneous Hydrogenation of Secondary and Primary Amides.CHEMINFORM, Issue 50 2007Angel A. Nunez Magro Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Parahydrogen induced polarization of barbituric acid derivatives: 1H hyperpolarization studiesMAGNETIC RESONANCE IN CHEMISTRY, Issue 8 2008Meike Roth Abstract Homogeneous hydrogenation of barbituric acid derivatives with parahydrogen yields a substantial increase of the 1H NMR signals of the reaction products. These physiologically relevant compounds were hydrogenated at both ambient and elevated temperatures and pressures using a standard cationic rhodium catalyst. The resulting nonthermal nuclear spin polarization (hyperpolarization) is limited by the spin,lattice relaxation time T1 of the corresponding nuclei in the products, being shorter than the time constant of the hydrogenation. The signal-to-noise ratio of the NMR spectra could be further increased upon signal averaging the antiphase PHIP signals of 25 successive scans following 30° pulse experiments and a delay of 10 s. Copyright © 2008 John Wiley & Sons, Ltd. [source] (R,R)-Tricarbonyl{,6 -1-(diphenylphosphino)-2-[1-(diphenylphosphino)ethyl]benzene}chromium(0), (R,R)-tricarbonyl-1,3C -{,-1(,6):2,2P,P,-1-(diphenylphosphino)-2-[1-(diphenylphosphino)ethyl]benzene}[2(,4)-norbornadiene]chromium(0)rhodium(I) tetrafluoroborate methanol 0.75-solvate and (R,R)-tricarbonyl-1,3C -{,-1(,6):2,2P,P,-1-(diphenylphosphino)-2-[1-(diphenylphosphino)ethyl]benzene}[2(,4)-(Z,Z)-cycloocta-1,5-diene]chromium(0)rhodium(I) tetrafluoroborate methanol 1.5-solvateACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2004Wolfgang Braun The title mononuclear chromium compound, [Cr(C32H28P2)(CO)3], (I), and its rhodium complexes [CrRh(C7H8)(C32H28P2)(CO)3]BF4·0.75CH4O, (II), and [CrRh(C8H12)(C32H28P2)(CO)3]BF4·1.5CH4O, (III), prepared as a ligand and precatalysts, respectively, for application in asymmetric homogeneous hydrogenation, have been studied by single-crystal X-ray diffraction. The structures of the free and complexed ligand are compared. It was found that the backbone of the ligand remains rigid on coordination, while only minor conformational changes of its side chains are observed. Both elements of central and planar chirality seem to build a well defined chiral environment for stereoselective catalysis. [source] | ||||||||||