- Heterometallic Mg?Ba Hydride Clusters in Hydrogenation Catalysis
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Reaction of a MgN“2/BaN”2 mixture (N“=N(SiMe3)2) with PhSiH3 gave three unique heterometallic Mg/Ba hydride clusters: Mg5Ba4H11N”7 ? (benzene)2 (1), Mg4Ba7H13N“9 ? (toluene)2 (2) and Mg7Ba12H26N”12 (3). Product formation is controlled by the Mg/Ba ratio and temperature. Crystal structures are described. While 3 is fully insoluble, clusters 1 and 2 retain their structures in aromatic solvents. DFT calculations and AIM analyses indicate highly ionic bonding with Mg?H and Ba?H bond paths. Also unusual H????H? bond paths are observed. Catalytic hydrogenation with MgN“2, BaN”2 and the mixture MgN“2/BaN”2 has been studied. Whereas MgN“2 is only active in imine hydrogenation, alkene and alkyne hydrogenation needs the presence of Ba. The catalytic activity of the MgN”2/BaN“2 mixture lies in general between that of its individual components and strong cooperative effects are not evident.
- Wiesinger, Michael,Knüpfer, Christian,Elsen, Holger,Mai, Jonathan,Langer, Jens,Harder, Sjoerd
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p. 4567 - 4577
(2021/09/09)
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- Mononuclear calcium complex as effective catalyst for alkenes hydrogenation
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Hydrogenolysis of the scorpionate-supported calcium benzyl complex [(TpAd,iPr)Ca(p-CH2C6H4-Me)(THP)] (TpAd,iPr= hydrotris(3-adamantyl-5-isopropyl-pyrazolyl)borate, THP = tetrahydropyran) (2-THP) afforded the mononuclear calcium hydrido complex [(TpAd,iPr)Ca(H)(THP)] (3). Under mild conditions (40 °C, 10 atm H2, 5 mol% cat.), complex3effectively catalyzed the hydrogenation of a variety of alkenes, including activated alkenes, semi-activated alkenes, non-activated terminal and internal alkenes. Mononuclear calcium unsubstituted alkyl complex [(TpAd,iPr)Ca{(CH2)4Ph}(THP)] (6), proposed as the catalytic hydrogenation intermediate, was isolated and structurally characterized.
- Shi, Xianghui,Hou, Cuiping,Zhao, Lanxiao,Deng, Peng,Cheng, Jianhua
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supporting information
p. 5162 - 5165
(2020/05/26)
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- One-pot synthesis of aldoximes from alkenes: Via Rh-catalysed hydroformylation in an aqueous solvent system
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Aldoxime synthesis directly starting from alkenes was successfully achieved through the combination of hydroformylation and subsequent condensation of the aldehyde intermediate with aqueous hydroxylamine in a one-pot process. The metal complex Rh(acac)(CO)2 and the water-soluble ligand sulfoxantphos were used as the catalyst system, providing high regioselectivities in the initial hydroformylation. A mixture of water and 1-butanol was used as an environmentally benign solvent system, ensuring sufficient contact of the aqueous catalyst phase and the organic substrate phase. The reaction conditions were systematically optimised by Design of Experiments (DoE) using 1-octene as a model substrate. A yield of 85% of the desired linear, terminal aldoxime ((E/Z)-nonanal oxime) at 95% regioselectivity was achieved. Other terminal alkenes were also converted successfully under the optimised conditions to the corresponding linear aldoximes, including renewable substrates. Differences of the reaction rate have been investigated by recording the gas consumption, whereby turnover frequencies (TOFs) >2000 h-1 were observed for 4-vinylcyclohexene and styrene, respectively. The high potential of aldoximes as platform intermediates was shown by their subsequent transformation into the corresponding linear nitriles using aldoxime dehydratases as biocatalysts. The overall reaction sequence thus allows for a straightforward synthesis of linear nitriles from alkenes with water being the only by-product, which formally represents an anti-Markovnikov hydrocyanation of readily available 1-alkenes.
- Gr?ger, H.,Guntermann, A.,Hinzmann, A.,Jolmes, T.,Panke, D.,Plass, C.,R?sler, J.,Seidensticker, T.,Terhorst, M.,Vogt, D.,Vorholt, A. J.
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supporting information
p. 7974 - 7982
(2020/11/30)
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- Electronic Ligand Modifications on Cobalt Complexes and Their Application toward the Semi-Hydrogenation of Alkynes and Para-Hydrogenation of Alkenes
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The effect of the electronic modification of a bis(carbene) pincer ligand, (MesCCCR), on cobalt catalysis has been investigated. The pincer ligand was modified in the para position of the aryl backbone with a tert-butyl and trifluoromethyl moiety to yield the electronic variants that were applied toward the synthesis and characterization of several cobalt complexes, (MesCCCR)Co. The application of the (MesCCCR)CoI(N2)PPh3 complexes toward the semihydrogenation of alkynes revealed that while the tert-butyl group does not impact reactivity, the loss of electron density at the metal center, by the installation of the CF3 group, does affect product ratios. Further inspection of the proposed mechanism suggested that the installation of the trifluoromethyl group slows down olefin hydrogenation. This finding was further supported in the application of the (MesCCCR)CoI-py (py = pyridine) complexes toward the parahydrogenation of ethyl acrylate, which demonstrated that the electron-withdrawing ligand variant produced less polarization.
- Muhammad, Safiyah R.,Nugent, Joseph W.,Tokmic, Kenan,Zhu, Lingyang,Mahmoud, Jumanah,Fout, Alison R.
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supporting information
p. 3132 - 3138
(2019/08/26)
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- Alkene Transfer Hydrogenation with Alkaline-Earth Metal Catalysts
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The alkene transfer hydrogenation (TH) of a variety of alkenes has been achieved with simple AeN′′2 catalysts [Ae=Ca, Sr, Ba; N′′=N(SiMe3)2] using 1,4-cyclohexadiene (1,4-CHD) as a H source. Reaction of 1,4-CHD with AeN′′2 gave benzene, N′′H, and the metal hydride species N′′AeH (or aggregates thereof), which is a catalyst for alkene hydrogenation. BaN′′2 is by far the most active catalyst. Hydrogenation of activated C=C bonds (e.g. styrene) proceeded at room temperature without polymer formation. Unactivated (isolated) C=C bonds (e.g. 1-hexene) needed a higher temperature (120 °C) but proceeded without double-bond isomerization. The ligands fully control the course of the catalytic reaction, which can be: 1) alkene TH, 2) 1,4-CHD dehydrogenation, or 3) alkene polymerization. DFT calculations support formation of a metal hydride species by deprotonation of 1,4-CHD followed by H transfer. Convenient access to larger quantities of BaN′′2, its high activity and selectivity, and the many advantages of TH make this a simple but attractive procedure for alkene hydrogenation.
- Bauer, Heiko,Thum, Katharina,Alonso, Mercedes,Fischer, Christian,Harder, Sjoerd
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supporting information
p. 4248 - 4253
(2019/03/07)
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- Distinct Catalytic Performance of Cobalt(I)- N -Heterocyclic Carbene Complexes in Promoting the Reaction of Alkene with Diphenylsilane: Selective 2,1-Hydrosilylation, 1,2-Hydrosilylation, and Hydrogenation of Alkene
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Selectivity control on the reaction of alkene with hydrosilane is a challenging task in the development of non-precious-metal-based hydrosilylation catalysts. While the traditional way of selectivity control relies on the use of different ligand type and/or different metals, we report herein that cobalt(I) complexes bearing different N-heterocyclic carbene ligands (NHCs) exhibit distinct selectivity in catalyzing the reaction of alkene with Ph2SiH2. [(IAd)(PPh3)CoCl] (IAd = 1,3-diadamantylimidazol-2-ylidene) is an efficient catalyst for anti-Markovnikov hydrosilylation of monosubstituted alkenes. [(IMes)2CoCl] (IMes = 1,3-dimesitylimidazol-2-ylidene) shows Markovnikov-addition selectivity in promoting the hydrosilylation of aryl-substituted alkenes. [(IMe2Me2)4Co][BPh4] (IMe2Me2 = 1,3-dimethyl-4,5-dimethylimidazol-2-ylidene) can catalyze hydrogenation of alkenes with Ph2SiH2 as the terminal hydrogen source. Mechanistic studies in combination with the knowledge on the steric nature of cobalt-NHC species suggest that (NHC)cobalt(I) silyl species and bis(NHC)cobalt(I) hydride species are the probable key intermediates for these hydrosilylation and hydrogenation reactions, respectively. The different steric nature of IAd versus IMes and the potential of IMes incurring π···π interaction with aryl-substituted alkenes are thought to be the causes of the observed 1,2- and 2,1-addition selectivity.
- Gao, Yafei,Wang, Lijun,Deng, Liang
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p. 9637 - 9646
(2018/10/02)
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- Simple Alkaline-Earth Metal Catalysts for Effective Alkene Hydrogenation
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Alkaline earth metal amides (AeN′′2: Ae=Ca, Sr, Ba, N′′=N(SiMe3)2) catalyze alkene hydrogenation (80–120 °C, 1–6 bar H2, 1–10 mol % cat.), with the activity increasing with metal size. Various activated C=C bonds (styrene, p-MeO-styrene, α-Me-styrene, Ph2C=CH2, trans-stilbene, cyclohexadiene, 1-Ph-cyclohexene), semi-activated C=C bonds (Me3SiCH=CH2, norbornadiene), or non-activated (isolated) C=C bonds (norbornene, 4-vinylcyclohexene, 1-hexene) could be reduced. The results show that neutral Ca or Ba catalysts are active in the challenging hydrogenation of isolated double bonds. For activated alkenes (e.g. styrene), polymerization is fully suppressed due to fast protonation of the highly reactive benzyl intermediate by N′′H (formed in the catalyst initiation). Using cyclohexadiene as the H source, the first Ae metal catalyzed H-transfer hydrogenation is reported. DFT calculations on styrene hydrogenation using CaN′′2 show that styrene oligomerization competes with styrene hydrogenation. Calculations also show that protonation of the benzylcalcium intermediate with N′′H is a low-energy escape route, thus avoiding oligomerization.
- Bauer, Heiko,Alonso, Mercedes,Fischer, Christian,R?sch, Bastian,Elsen, Holger,Harder, Sjoerd
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supporting information
p. 15177 - 15182
(2018/10/24)
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- Synthesis of Bis(phosphino)silyl Pincer-Supported Iron Hydrides for the Catalytic Hydrogenation of Alkenes
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The synthesis and characterization of Fe pincer complexes supported by a bis(phosphino)silyl (PSiP) ligand are described. While four-coordinate species of the type (PSiP)FeX (X = halide) proved challenging to access, examples of five-coordinate (PSiP)Fe(II) and (PSiP)Fe(I) species were prepared and crystallographically characterized. In studying the reactivity of such (PSiP)Fe precursors, a variety of iron hydride species were observed and characterized, and interconversion among such complexes facilitated by the coordination of N2 was noted. The structures and spectroscopic features of several such diamagnetic Fe(II) hydrides were elucidated, including that of a unique and highly stable η2-(Si-H)Fe(II) dihydride complex. A surrogate for a low coordinate (PSiP)FeH species in the form of its bis(dinitrogen) adduct was found to be an effective precatalyst for the direct hydrogenation of alkenes, including various mono- and disubstituted aliphatic alkenes, as well as a trisubstituted example. Esters and ethers were found to be well-tolerated by the catalyst, and alkyne hydrogenation was also demonstrated.
- Murphy, Luke J.,Ferguson, Michael J.,McDonald, Robert,Lumsden, Michael D.,Turculet, Laura
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p. 4814 - 4826
(2018/12/11)
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- Regio- and Chemoselective Hydrogenation of Dienes to Monoenes Governed by a Well-Structured Bimetallic Surface
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Unprecedented surface chemistry, governed by specific atomic arrangements and the steric effect of ordered alloys, is reported. Rh-based ordered alloys supported on SiO2 (RhxMy/SiO2, M = Bi, Cu, Fe, Ga, In, Pb, Sn, and Zn) were prepared and tested as catalysts for selective hydrogenation of trans-1,4-hexadiene to trans-2-hexene. RhBi/SiO2 exhibited excellent regioselectivity for the terminal C=C bond and chemoselective hydrogenation to the monoene, not to the overhydrogenated alkane, resulting in a high trans-2-hexene yield. Various asymmetric dienes, including terpenoids, were converted into the corresponding inner monoenes in high yields. This is the first example of a regio- and chemoselective hydrogenation of dienes using heterogeneous catalysts. Kinetic studies and density functional theory calculations revealed the origin of the high selectivity: (1) one-dimensionally aligned Rh arrays geometrically limit hydrogen diffusion and attack to alkenyl carbons from one direction and (2) adsorption of the inner C=C moiety to Rh is inhibited by steric repulsion from the large Bi atoms. The combination of these effects preferentially hydrogenates the terminal C=C bond and prevents overhydrogenation to the alkane.
- Miyazaki, Masayoshi,Furukawa, Shinya,Komatsu, Takayuki
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p. 18231 - 18239
(2017/12/27)
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- Well-Defined Cobalt(I) Dihydrogen Catalyst: Experimental Evidence for a Co(I)/Co(III) Redox Process in Olefin Hydrogenation
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The synthesis of a cobalt dihydrogen CoI-(H2) complex prepared from a CoI-(N2) precursor supported by a monoanionic pincer bis(carbene) ligand, MesCCC (MesCCC = bis(mesityl-benzimidazol-2-ylidene)phenyl), is described. This species is capable of H2/D2 scrambling and hydrogenating alkenes at room temperature. Stoichiometric addition of HCl to the CoI-(N2) cleanly affords the CoIII hydridochloride complex, which, upon the addition of Cp2ZrHCl, evolves hydrogen gas and regenerates the CoI-(N2) complex. Furthermore, the catalytic olefin hydrogenation activity of the CoI species was studied by using multinuclear and parahydrogen (p-H2) induced polarization (PHIP) transfer NMR studies to elucidate catalytically relevant intermediates, as well as to establish the role of the CoI-(H2) in the CoI/CoIII redox cycle.
- Tokmic, Kenan,Markus, Charles R.,Zhu, Lingyang,Fout, Alison R.
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supporting information
p. 11907 - 11913
(2016/10/07)
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- Bis(imino)pyridine cobalt-catalyzed dehydrogenative silylation of alkenes: Scope, mechanism, and origins of selective allylsilane formation
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The aryl-substituted bis(imino)pyridine cobalt methyl complex, ( MesPDI)CoCH3 (MesPDI = 2,6-(2,4,6-Me 3C6H2-N=CMe)2C5H 3N), promotes the catalytic dehydrogenative silylation of linear α-olefins to selectively form the corresponding allylsilanes with commercially relevant tertiary silanes such as (Me3SiO) 2MeSiH and (EtO)3SiH. Dehydrogenative silylation of internal olefins such as cis- and trans-4-octene also exclusively produces the allylsilane with the silicon located at the terminus of the hydrocarbon chain, resulting in a highly selective base-metal-catalyzed method for the remote functionalization of C-H bonds with retention of unsaturation. The cobalt-catalyzed reactions also enable inexpensive α-olefins to serve as functional equivalents of the more valuable α, ω-dienes and offer a unique method for the cross-linking of silicone fluids with well-defined carbon spacers. Stoichiometric experiments and deuterium labeling studies support activation of the cobalt alkyl precursor to form a putative cobalt silyl, which undergoes 2,1-insertion of the alkene followed by selective β-hydrogen elimination from the carbon distal from the large tertiary silyl group and accounts for the observed selectivity for allylsilane formation.
- Atienza, Crisita Carmen Hojilla,Diao, Tianning,Weller, Keith J.,Nye, Susan A.,Lewis, Kenrick M.,Delis, Johannes G. P.,Boyer, Julie L.,Roy, Aroop K.,Chirik, Paul J.
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supporting information
p. 12108 - 12118
(2014/10/16)
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- METHOD FOR HYDROFORMYLATION OF UNSATURATED COMPOUNDS
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The invention relates to a method for hydroformylation of unsaturated compounds such as olefins and alkynes using mixtures of synthesis gas (CO/H2), in which either the unsaturated compounds and a catalyst are heated to a reaction temperature of 60 to 200° C. and the synthesis gas is then added, or the unsaturated compounds and the catalyst are brought into contact with pure CO at normal temperature in a preformation step, then are heated to reaction temperature and on reaching the reaction temperature the CO is replaced by the synthesis gas. The pressure is 1 to 200 bar and the CO:H2 ratio in the synthesis gas is in the range from 1:1 to 50:1. The iridium catalyst used comprises a phosphorus-containing ligand in the iridium:ligand ratio in the range from 1:1 to 1:100. With high catalyst activities and low catalyst use, very high turnover frequencies are achieved.
- -
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Paragraph 0088
(2014/02/16)
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- Only para-hydrogen spectroscopy (OPSY), a technique for the selective observation of para-hydrogen enhanced NMR signals
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An NMR method is reported for the efficient removal of signals derived from nuclei with thermally equilibrated spin state populations whilst leaving, intact, signals derived from para-hydrogen induced polarisation (PHIP) through gradient assisted coherence selection. The Royal Society of Chemistry.
- Aguilar, Juan A.,Elliott, Paul I. P.,Lopez-Serrano, Joaquin,Adams, Ralph W.,Duckett, Simon B.
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p. 1183 - 1185
(2008/02/02)
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- "Hydrogen-catalyzed" dehydrogenation: A supercritical conundrum
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Hot spots: The surprising, apparently catalytic effect of H2 in the dehydrogenation of 1 in supercritical CO2 is the result of thermal hot spots (see thermal image of reactor) generated in the catalyst bed by an initial exothermic hy
- Hyde, Jason R.,Walsh, Ben,Poliakoff, Martyn
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p. 7588 - 7591
(2007/10/03)
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- An excellent nickel boride catalyst for the selective hydrogenation of olefins
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Nickel boride prepared on borohydride exchange resin (BER) in methanol is an excellent catalyst for the selective hydrogenation of olefins. Thus, monosubstituted olefins and norbornene were hydrogenated quantitatively at 0°C in 1 hour in the presence of disubstituted olefins and trisubstituted α,β-unsaturated acid derivatives, the disubstituted olefins in turn were hydrogenated at 65°C in 1 hour without affecting trisubstituted olefins, benzene, and heteroaromatic compounds.
- Choi, Jaesung,Yoon, Nung Min
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p. 597 - 599
(2007/10/03)
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- Selective Hydrogenation of Substituted Dienes Catalyzed by an Organoyttrium Complex
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Cp*2YMe(THF) has been developed as an efficient catalyst for the selective reduction of substituted dienes.
- Molander, Gary A.,Hoberg, John O.
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p. 3266 - 3268
(2007/10/02)
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- Homogeneous catalytic hydrosilylation of the C=C double bond in the presence of transition metal catalysts
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Hydrosilylation of unsaturated esters and other vinyl- and vinylidene type olefins has been carried out with PtCl2(PhCN)2, RhCl(PPh3)3 and platinum-phosphine catalysts.With PtCl2(PhCN)2 and platinum(0)-phosphine complexes as catalysts the hydrosilylation of methyl methacrylate gave the linear product 2a, whereas in the RhCl(PPh3)-catalyzed reaction the silyl ketene acetal derivative 4a was formed selectively.In the reactions of other esters and unsaturated hydrocarbons the main product is highly dependent on the structure of the substrate, but the catalyst used is also very important.With unsaturated hydrocarbons the selectivity is rather poor, but in the case of 1-vinyl-2-pyrrolidinone the linear- (9e) and the branched hydrosilylated derivative (10e) are formed in high yields depending on the catalyst used.The platinum(II)-phosphine complexes are inactive in the absence of air, but some platinum(0)-phosphine catalysts are also effective under argon in the hydrosilylation of methyl methacrylate.
- Skoda-Foeldes, Rita,Kollar, Laszlo,Heil, Balint
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p. 297 - 304
(2007/10/02)
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- Photochemical Dehydrogenation of Alkanes Catalyzed by trans-Carbonylchlorobis(trimethylphosphine)rhodium: Aspects of Selectivity and Mechanism
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The photochemical dehydrogenation of alkanes is catalyzed in solution by trans-Rh(PMe3)2(CO)Cl with high efficiency; quantum yields up to 0.10 and turnover numbers as high as 5000 are achieved with cyclooctane as substrate.The intramolecular regioselectivity of the reaction is investigated with methyl-, ethyl-, and isopropylcyclohexane.In competition experiments, cyclooctane is found to be 17 times as reactive as cyclohexane; under carbon monoxide atmosphere, the selectivity is enhanced to a factor of 130.A kinetic isotope effect, kH/kD=5.3, is found for thedehydrogenation of C6H12/C6D12.Both intra- and intermolecular selectivities are consistent with a pathway involving a reversible C-H oxidative addition followed by a β-hydrogen elimination. trans-Rh(PMe3)2(CO)Cl is demonstrated to be the only significant photoactive species in solution.The dehydrogenation reaction is quenched by carbon monoxide with Stern-Volmer kinetics.On the basis of these results, a mechanism is proposed in which the enrgy needed to drive these thermodynamically unfavorable dehydrogenations is obtained only from Rh-CO bond photolysis.
- Maguire, John A.,Boese, William T.,Goldman, Alan S.
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p. 7088 - 7093
(2007/10/02)
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- Studies on organolanthanide complexes. XVIII. The reduction and isomerization of olefins with tricyclopentadienyllanthanides/sodium hydride
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Reduction of 1-hexene with Cp3Ln/NaH (Cp=cyclopentadienyl, Ln=rare earth metals) in THF at 45 deg C, after hydrolysis, gives hexane.The reducing activity of Cp3Ln depends strongly upon the ionic radius of the trivalent rare earth ion.The activity and selectivity of early rare earths for 1-hexene reduction are higher than those of heavy rare earths.The Cp3Ln/NaH systems can be used to regioselectively reduce dienes which contain a terminal carbon-carbon double bond as well as an internal one with high yield.Selectivity is 100percent.Moreover, the Cp3Ln/NaH systems are able to catalyze the hydrogenation of olefins.When Cp3Ln/NaH is used as catalyst, 1-hexene was isomerized at 45 deg C to cis-2-hexene and to trans-2-hexene in excellent yields.In contrast to reducing activity, the catalytic activity of heavy rare earths in the isomerization reaction is higher than that of the early earths.Hence, Cp3Sm/NaN and Cp3Y/NaH are new reducing agents and catalysts for 1-hexene reduction and isomerization, respectively.
- Qian, Changtao,Ge, Yuanwen,Deng, Daoli,Gu, Yongjie,Zhang, Caihua
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p. 175 - 184
(2007/10/02)
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- Reduction of Ethylenic Insaturations by in situ Generated Hydrogen
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Selective hydrogenation of carbon-carbon double bond can be easily performed by simultaneous addition of substrate and Me3SiCl or water to NiCRA.It is shown that it is possible to reduce dienes selectively in olefins and carbon-carbon double bond in the presence of carbonyl, ester or acid groups.
- Fort, Y.,Vanderesse, R.,Caubere, P.
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p. 757 - 760
(2007/10/02)
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- Light-promoted catalytic hydrogenation of olefins with nickel complexes: the formation of nickel hydrides from the reaction of Ni(I) complexes with hydrogen
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The conditions pertaining to triplet excited state ketone-sensitized photoreduction of Ni(acac)2 under hydrogen were show to serve as a method for light-promoted hydrogenation of olefins with clean chemospecificity.For example, the double bond in the bicyclic system was preferentially hydrogenated over the other double bond in dicyclopentediene and in 5-methylenebicycloheptene.This photohydrogenation could be run under a wide range of conditions and was apparently a homogeneous catalytic process; in a late stage of photohydrogenation, concurrence of heterogeneous catalytic processes was not ruled out.The Ni(I) complexes of tetrahydrofuran and olefins generated from the photoreduction of Ni(acac)2 were shown to react with hydrogen to give nickel hydride complexes.By analogy with the generally accepted reaction pattern, coordinated olefins in these nickel hydride complexes probably spontaneously undergo intramolecular addition to give Ni-alkyl complexes.It is suggested, that these Ni-alkyl complexes are photoexcited to generate a vacant coordination site so that the reaction with hydrogen can proceed to give products and regenerate a nickel hydride catalyst.
- Chow, Yuan L.,Li, Huali,Yang, Meng-Su
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p. 2920 - 2927
(2007/10/02)
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- CATALYTIC HYDROGENATION OF OLEFINS IN BIPHASIC WATER-LIQUID SYSTEM
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Cyclic and linear olefins and polyenes with or without functional groups are hydrogenated under very mild reaction conditions.Emphasis is put on the advantages of this method which requires no solvent and a water-soluble non air-sensitive catalyst.
- Larpent, Chantal,Dabard, Renee,Patin, Henri
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p. 2507 - 2510
(2007/10/02)
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- Silica-Supported Cyclopentadienyl-Rhodium(I),-Cobalt(I), and-Titanium(IV) Complexes
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The silylated cyclopentadiene derivative, (MeO)3Si(CH2)3C5H5, synthesised from commercially-available (MeO)3Si(CH2)3Cl, has been used to prepare the complexes 5-(MeO)3Si(CH2)3C5H4>Rh(CO)2, 5(MeO)3Si(CH2)3C5H4>Rh(COD)(COD= cyclo-octa-1,5-diene), and 5-(MeO)3Si(CH2)3C5H4>2TiCl2.The complexes 5(MeO)3Si(CH2)3C5H4>TiCl3, prepared by reaction of NaC5H4(CH2)3Si(OMe)3 with TiCl4 (1/1 molar ratio) and also by reaction of 5-(MeO)3Si(CH2)3C5H4>Ti(OEt)3 with CH3COCl, proved to be very unstable.Attempts to synthesise the complex 5-(MeO)3Si(CH2)3C5H4>(η5-C5H5)TiCl2, either by reaction of 5-(MeO)3Si(CH2)3C5H4>TiCl3 with NaC5H4 or reaction of (η5-C5H5)TiCl3 with NaC5H4(CH2)3Si(OMe)3, gave none of the expected product and only (η5-C5H5)TiCl2 could be isolated from these reactions.The cyclo-octadiene rhodium complex supported on silica has been shown to be an efficient cyclotrimerization catalyst, and the silica-supported titanium complex SIL-(CH2)3C5H4)TiCl2 is, after reduction with butyllithium, an efficient and selective catalyst for the hydrogenation of alk-1-enes.
- Booth, B. L.,Ofunne, G. C.,Stacey, C.,Tait, P. J. T.
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p. 143 - 156
(2007/10/02)
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- ACTIVATION OF REDUCING AGENTS. SODIUM HYDRIDE CONTAINING COMPLEX REDUCING AGENTS 24. BENEFICIAL EFFECT OF Me3SiCl ON THE REDUCING PROPERTIES OF NiCRA
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Reduction of carbon-carbon double bonds can be achieved with either NiCRA or NiCRASi (nickel containing Complex Reducing Agent activated by Me3SiCl).Selective reduction of polyunsaturated hydrocarbons or unsaturated ketones are easily performed with both reagents.
- Fort, Y,Vanderesse, R,Caubere, P
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p. 5487 - 5490
(2007/10/02)
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- HYDROGENATION OF OLEFINS WITH CATIONIC RHODIUM COMPLEX INTERCALATED IN FLUORO TETRASILICIC MICA
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The hydrogenation of olefins was studied with a Rh complex catalyst intercalated in a synthetic mica.Steric influence due to the interlayers on the hydrogenation rate is observed not with aliphatic olefins but with cycloolefins.The intercalated catalyst shows enhanced selectivity relative to the homogeneous catalyst in the hydrogenation of 4-vinylcyclohexene.
- Miyazaki, Takayuki,Tsuboi, Akio,Urata, Hisao,Suzuki, Hiroharu,Morikawa, Yutaka,et al.
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p. 793 - 796
(2007/10/02)
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- RATE OF REACTION OF ORGANIC ACIDS WITH UNSATURATED BRIDGED BICYCLIC HYDROCARBONS
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The rate constants were determined for the addition of acetic acid and trifluoroacetic acid to 15 unsaturated hydrocarbons with the bicycloheptane, bicyclo- and bicyclooctane, and cyclohexene structures.The reactivity of the compounds
- Bobyleva, A. A.,Belikova, N. A.,Dzhigirkhanova, A. V.,Plate, A. L.
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p. 797 - 804
(2007/10/02)
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- A NOVEL ZIRCONIUM-CATALYZED HYDROALUMINATION OF OLEFINS
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Sterically hindered trialkylalanes, such as triisobutylalane, react with olefins at or below room temperature under the influence of a catalytic amount of Cl2ZrCp2 to effect hydroalumination of the olefins.The reaction can tolerate certain hetero-functional groups, such as OH, SPh and Br, which tend to interfere with previously reported hydroalumination procedures.
- Negishi, Ei-ichi,Yoshida, Tadao
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p. 1501 - 1504
(2007/10/02)
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