- Nickel Hydride Complexes Supported by a Pyrrole-Derived Phosphine Ligand
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The synthesis of two nickel hydride complexes bearing the pyrrole-derived phosphine ligand CyPNH (2-(dicyclohexylphosphino)methyl-1H-pyrrole) was developed, namely, (κP-CyPNH)(κP,κN-CyPN)NiH and the acid-stable trans-(κP-CyPNH)2Ni(OAc)H·HOAc. (κP-CyPNH)(κP,κN-CyPN)NiH stoichiometrically reduces benzaldehyde and acetophenone in a metal-ligand cooperative manner and catalytically dimerizes ethylene and cycloisomerizes 1,5-cyclooctadiene and 1,5-hexadiene. trans-(κP-CyPNH)2Ni(OAc)H·HOAc, available from the protonation of (κP-CyPNH)(κP,κN-CyPN)NiH with acetic acid, catalyzes the cycloisomerization of 1,5-cyclooctadiene more effectively and produces the less thermodynamically favored cycloisomers of 1,5-cyclooctadiene.
- Collett, Joel D.,Guan, Hairong,Krause, Jeanette A.
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p. 345 - 353
(2022/02/16)
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- PROCESS FOR THE PREPARATION OF 1-METHYLCYCLOPENTANE DERIVATIVES
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Process for the preparation of 1-methylcyclopentene by thermal reaction of cyclohexanol or cyclohexene or mixtures of both compounds to give 1-methylcyclopentene, wherein the resulting by-products 3-methylcyclopentene and 4-methylcyclopentene (double-bond isomers of 1-methylcyclopentene) are returned to the reaction.
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Page/Page column 5
(2012/05/04)
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- Kinetics and modeling of the thermal reaction of propene at 800 K. Part III. Propene in the presence of small amounts of oxygen
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The thermal reaction of propene was studied around 800 K in the presence of less than 20% O. Initially, the production of H2, CH4, C2H4, C2H6, allene, C3H8, 1,3-butadiene, butenes, 3- and 4-methylcyclopentene, a mixture of 1,4- and 1,5-hexadienes, methylcyclopentane, 4-methylpent-1-ene, and hex-1-ene, was observed along with H2O2, CO, and small quantities of ethanal and CO2. O increases the initial production of H and of most hydrocarbons and, particularly, that of C6 dienes and of cyclenes. A kinetic scheme is proposed in which chains are primarily initiated by a bimolecular step which competes with the second-order initiation of propene pyrolysis. Modeling of the reaction based on the proposed scheme accounts well for the concentration-time profiles.
- Barbe,Baronnet,Martin,Perrin
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p. 503 - 522
(2007/10/03)
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- THE ROLE OF THE 1,2-HYDRIDE SHIFT IN THE ISOMERIZATION PROCESSES OF CYCLOALKYL CARBOCATIONS
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The role of successive 1,2-hydride shifts in the isomerization processes of cycloalkylcarbonium ions was demonstrated for the case of the alkylation of isomeric methylcyclopentanols or methylcyclopentenes in the presence of sulfuric acid and the isomerization of cyclohexene at acidic aluminum oxide.
- Voronenkov, V. V.,Dzyuba, I. B.,Kryukov, S. I.,Zhdankin, V. V.
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p. 2236 - 2238
(2007/10/02)
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- Formation de coke, desactivation et regeneration des zeolithes. IV - Transfert d'hydrogene et formation de coke au cours de la transformation du cyclohexene sur une zeolithe USHY. Influence de la temperature de reaction
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On a ultrastabilized protonic Y zeolite (USHY) cyclohexene undergoes various reactions: isomerization into methylcyclopentenes, hydrogen transfer, cracking and formation of carbonaceous deposits ("coke").The transfer of hydrogen which comes either from cyclohexene (with formulation of benzene) or from heavy carbonaceous compounds causes the saturation of cyclohexene and of methylcyclopentenes.While the total transformation rate increases when the temperature increases, the rate of coke formation decreases slightly.This abnormal effect can be due to a modification in the composition of heavy carbonaceous compounds held back in the zeolite pores.The relative significance of various reactions depends very much on the temperature: at 120 deg C "coke" formation is faster than isomerization and much faster than hydrogen transfer, the hydrogen implicated coming from heavy carbonaceous compounds only.From 200 deg C upwards, isomerization and hydrogen transfer become the main reactions.Even if the production of benzene increases significantly with the temperature, hydrogen always comes mainly from the heavy carbonaceous compounds and is transfered faster to methylcyclopentenes than to cyclohexene.Light compounds resulting from the cracking of methylcyclopentenes appear above 350 deg C.The formation of all the products can be explained by mechanisms in which carbenium ion intermediates intervene.
- Magnoux, Patrick,Gallet, Alain,Guisnet, Michel
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p. 810 - 814
(2007/10/02)
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- THE EFFECT OF TITANIUM AND SODIUM IN ALUMINA ON ITS ACIDIC AND CATALYTIC PROPERTIES
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Acidic and catalytic properties of alumina containing amall amounts of Ti(IV) and Na(I) (up to 1 wt.percent of both) were examined.It has been proved that the amount of acid sites with the strength H0 /= 3.3 and the initial reaction rates of cyclohexene isomerisation depend linearly on calculated total electronegativity of the corresponding mixture of oxides.
- Kiratova, Kveta,Rocek, Josef
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- Copper(II) Triflate, a New Reagent for Mild Dehydration of Alcohols: Synthetic Usefulness and Mechanistic Insight
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The effectiveness of copper(II) triflate (copper(II) trifluoromethanesulfonate) as a new dehydrating reagent for a variety of alcohols has been demonstrated.Based on several control experiments, a possible mechanism is suggested.
- Laali, Khosrow,Gerzina, Robert J.,Flajnik, Christine M.,Geric, Cynthia M.,Dombroski, Ann Marie
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p. 607 - 611
(2007/10/02)
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- Protium-deuterium exchange of cyclic and acyclic alkanens in dilute acid medium at elevated temperatures
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A modification of the high temperature - dilute acid (HTDA) method for deuterium labelling of aromatic compounds has been applied to the H-D exchange of a number of cyclic and acyclic alkenes.Cyclopentene, cyclohexene, cyclododecene, and tetramethylethylene have been completely exchanged in excellent yield. 1-Methylcyclopentene and 1-methylcyclohexene have also been perdeuterated and cycloheptene and cyclooctene partially labelled but require spinning band distillation or preparative glpc for separation from rearrangement products.A variety of C5-C8 acyclic alkeneshave also been treated under HTDA conditions.
- Werstiuk, Nick Henry,Timmins, George
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p. 530 - 533
(2007/10/02)
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- First Direct Synthesis of Optically Active 3-Methylcyclopentene
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(-)-(S)- and (+)-(R)-3-methylcyclopentene (1) has been prepared in a stereochemically unambiguous synthesis.The (S)-configuration for (-)-1 was confirmed by correlation with (-)-(S)-1-methylindane.
- Sliwka, Hans-Richard,Hansen, Hans-Juergen
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p. 434 - 440
(2007/10/02)
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- HYDROSTANNATION DU BICYCLOHEXENE-2: SYNTHESE ET IDENTIFICATION DES METHYL-4 ET METHYL-5 TRIMETHYLSTANNYL-3 CYCLOPENTENES DIASTEREOISOMERES
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4-Methyl- and 5-methyl-3-trimethylstannylcyclopentenes were obtained from bicyclohex-2-ene through hydrostannation.The four isomers were identified by chemical and physicochemical methods such as 90 MHz 1H FT NMR spectroscopy which gives some conformational information in the series of 5-methyl-3-trimethylstannylcyclopentenes.
- Dumartin, Gilles,Quintard, Jean-Paul,Pereyre, Michel
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