- Selective Catalytic Hydrogenation of Alicyclic Dienes with Hydrogen in a Liquid Phase
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Abstract: The hydrogenation behavior of a number of alicyclic dienes (5-vinyl-2-norbornene (5-vinyl-bicyclo[2.2.1]heptene-2), dicyclopentadiene (tricyclo[5.2.1.02,6]decadiene-3,8), and cis,cis-1,5-cyclooctadiene) to the corresponding cycloalkenes in the presence of a finely divided palladium catalyst suspended in the liquid phase has been studied. The reactivities of the double bonds of these dienes have been compared. The conversion of 5-vinyl-2-norbornene and selectivity of its hydrogenation to 2-vinylnorbornane depending on the reaction conditions have been evaluated. Conditions for the selective production of desired 2-vinylnorbornane are proposed for the further implementation of this process in practice.
- Bermeshev,Antonova,Shangareev,Danilova,Pozharskaya
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p. 869 - 875
(2018/10/15)
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- Reduced graphene oxide supported nickel-palladium alloy nanoparticles as a superior catalyst for the hydrogenation of alkenes and alkynes under ambient conditions
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Addressed herein is the superior catalytic performance of reduced graphene oxide supported Ni30Pd70 alloy nanoparticles (rGO-Ni30Pd70) for the direct hydrogenation of alkenes and alkynes to alkanes, which surpasses the commercial Pd/C catalyst both in activity and stability. A variety of cyclic or aromatic alkenes and alkynes (a total of 17 examples) were rapidly reduced to the corresponding alkanes with high yields (>99%) via the presented direct hydrogenation protocol under ambient conditions. Compared to the commercially available Pd/C (10 wt%) catalyst, the rGO-Ni30Pd70 catalyst provided higher yields in shorter reaction times under the optimized conditions. Moreover, the rGO-Ni30Pd70 catalysts were more stable and durable than the commercial Pd/C catalysts by preserving their initial activity after five consecutive runs in the hydrogenation reactions.
- ?etinkaya, Yasin,Metin, ?nder,Balci, Metin
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p. 28538 - 28542
(2016/04/08)
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- Oxygen-Deficient Tungsten Oxide as Versatile and Efficient Hydrogenation Catalyst
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Heterogeneous hydrogenation is one of the most important industrial operations, and reduced metals (mostly noble metals and a few inexpensive metals) generally serve as the catalyst to activate molecular H2. Herein we report oxygen-deficient tungsten oxide, such as WO2.72, is a versatile and efficient catalyst for the hydrogenation of linear olefins, cyclic olefins, and aryl nitro groups, with obvious advantages compared with non-noble metal nickel catalyst from the aspect of activity and selectivity. Density functional theory calculations prove the oxygen-deficient surface activates H2 very easily in both kinetics and thermodynamics. Testing on several oxygen-deficient tungsten oxides shows a linear dependence between the hydrogenation activity and oxygen vacancy concentration. Tungsten is earth-abundant, and WO2.72 can be synthesized in large scale using a low-cost procedure, which provides an ideal catalyst for industrial application. Because oxygen vacancy is a common characteristic of many metal oxides, the findings in this work may be extended to other metal oxides and thus provide the possibility for exploring a new type of hydrogenation catalyst.
- Song, Jiajia,Huang, Zhen-Feng,Pan, Lun,Zou, Ji-Jun,Zhang, Xiangwen,Wang, Li
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p. 6594 - 6599
(2015/11/18)
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- Unusual pathway of the tantalum-catalyzed carboalumination reaction of alkenes with triethylaluminum
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Carboalumination of 1-alkenes (1-hexene, 1-octene, 1-decene) with Et 3Al in the presence of catalytic amounts of TaCl5 results in a mixture of 2-(R-substituted)- and 3-(R-substituted)-n-butylaluminums (1:1 ratio) in total yields of 75-85%. The TaCl5-catalyzed reaction of bicyclo[2.2.1]hept-2-ene, endo-tricyclo[5.2.1.02,6]deca-3,8-diene, and (exo/endo)-5-methylbicyclo[2.1.1]hept-2-ene with Et3Al leads to the formation of diethyl[2-exo-(2′-norbornylethyl)]aluminums in high yields. DFT calculations confirm the thermodynamic preference of the final exo product. The multistep reaction mechanisms for the formation of the resultant organoaluminums through tantalacyclopentanes as key intermediates are also discussed.
- Sultanov, Rifkat M.,Samoilova, Elena V.,Popod'Ko, Natal'Ya R.,Tulyabaev, Artur R.,Sabirov, Denis Sh.,Dzhemilev, Usein M.
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supporting information
p. 6619 - 6623
(2013/11/19)
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- NEW ACHIEVEMENTS IN THE USE OF ZIRCONIUM COMPLEXES IN THE CHEMISTRY OF ORGANO-ALUMINIUM AND MAGNESIUM COMPOUNDS
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This paper describes some applications of a new reaction of catalytic cyclometallation of α-olefins, norbornenes and their derivatives, and 1,2-disubstituted acetylenes with organomagnesium and organoaluminium compounds effected by zirconium catalysts, leading to a series of five and macrocyclic heterocycles containing magnesium and aluminium.
- Dzhemilev, U. M.
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p. 4333 - 4346
(2007/10/02)
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- SOME NOVELTIES IN OLEFIN CARBOMETALLATION ASSISTED BY ALKYL-MAGNESIUM AND -ALUMINIUM DERIVATIVES AND CATALYZED BY ZIRCONIUM AND TITANIUM COMPLEXES
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Carbometallation of α-olefins, as well as of those containing functional groups, and of norbornene derivatives has been investigated with alkyl-magnesium and -aluminium compounds and found to proceed under mild conditions in the presence of catalytic quan
- Dzhemilev, U. M.,Vostrikova, O. S.
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- ESR Study of γ-Irradiated Substituted Norbornanes in Thiourea Clathrate and Adamantane Matrix. Novel 2-Norbornyl-Type Radicals
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The γ irradiation at 77 K of 2-methyl-2-ethylbicycloheptane and of 2-methylene-2-ethylidenebicycloheptene in the state of thiourea adducts leads to formation of 2-methyl- and 2-ethylnorbornyl radicals by loss of hydrogen atoms at the substituent sites or by partial hydrogenation of the double bonds.On warming above 77 K after irradiation, the 2-alkylnorbornyls add to double bonds of neighboring molecules yielding new adduct radicals alkylnorbornyl.The reactions can be reversed by UV irradiation at 77 K, thus suggesting that the addition does not proceed beyond the first step.A reaction model based on the geometrical control by the molecular packing within the clathrate channels has been proposed.The irradiation of 2-ethylidenenorbornene in the state of thiourea clathrate or trapped in adamantane matrix yields an allyl-type radical by loss of a hydrogen atom from the methyl group.The structure and ESR properties of 2-alkylnorbornyls and of the allylnorbornyl have been investigated by MO methods to the INDO and extended Hueckel levels of approximation.
- Faucitano, A.,Buttafava, A.,Martinotti, F. Faucitano,Cesca, S.
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p. 367 - 374
(2007/10/02)
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- Synthetic applications of α-hydroxydiazenes. III. Uncatalyzed and phenol catalyzed hydroalkylation of alkenes and of azobenzene with alkylazodiphenylmethanols
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Alkylazodiphenylmethanols (C6H5)2C(OH)N=NR, (R = CH(CH3)2, CH2CH3, CH3), when decomposed in the presence of olefinic substrates or in the presence of azobenzene, hydroalkylate those substrates.Addition of R and H across the double bond of an unsymmetric alkene occurs with the regiochemistry expected for a radical mechanism, in which the grooup R adds first.Radical intermediates from decomposition of alkylazodiphenylmethanols have been demonstrated earlier with spin trapping experiments.The fact that addition of phenol can enhance the yield of hydroalkylation product suggests that the process is a radical chain reaction, with chain carrying steps consisting of the reactions: (i) R. + CH2=CHY -> RCH2C.HY (ii) RCH2C.HY + (C6H5)2C(OH)N2R -> RCH2CH2Y + (C6H5)2CO + N2 + R..One deuterioalkylation and some yield-optimizing experiments are also reported.
- Yeung, Dominic W. K.,Warkentin, John
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p. 2386 - 2394
(2007/10/02)
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