- Copolymerization of ethylene with methylenecyclopropanes promoted by cobalt and nickel complexes
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The cobalt and nickel complexes promote addition polymerization of substituted methylenecyclopropanes as well as their copolymerization with ethylene to afford the polymers that contain three-membered rings. The homopolymerization of 2-aryl-1-methylenecyclopropane catalyzed by [CoCl 2(L)]-MMAO (L = bis(1-iminoalkyl)pyridine ligand) at -40°C produces the polymers -(CH2-CCH2CHAr)- with a narrow molecular weight distribution. The copolymer of ethylene and 2-aryl-1-methylenecyclopropane is also obtained by using the same catalyst. The ratio of the two monomer units varies in the range from 0 to 0.5 depending on the concentration of ethylene and 2-aryl-1-methylenecyclopropane. 13C{1H} NMR spectrum of the alternating copolymer exhibits a single sharp signal for each carbon of the repeating units. Ethylene and 7-methylenebicyclo[4.1.0]heptane also undergo alternating copolymerization to produce the polymer having the C4 repeating unit containing a bicyclic group. Heating the polymer at 130°C causes ring-opening isomerization to afford the polymer having a C=C double bond in the main chain. Mixtures of [Ni(π-C 3H5)Br]2, a diimine ligand, and cocatalysts such as NaBARF and Et2AlCl, initiate the copolymerization of ethylene with 2-aryl-1-methylenecyclopropane to give a random copolymer with a low molecular weight (Mn = 1000{2000).
- Takeuchi, Daisuke,Anada, Kouhei,Osakada, Kohtaro
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Read Online
- Arene hydrogenation in a room-temperature ionic liquid using a ruthenium cluster catalyst
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The air and moisture stable system [bmim][BF4]-[Ru4(η6-C6H6)4][BF4] {[bmim]+ = 1-butyl-3-methylimidazolium cation} presents a novel medium for conducting hydrogenations of arenes; the environmental problems associated with related aqueous-organic biphasic regimes are eliminated.
- Dyson, Paul J.,Ellis, David J.,Parker, David G.,Welton, Thomas
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Read Online
- Fabricating nickel phyllosilicate-like nanosheets to prepare a defect-rich catalyst for the one-pot conversion of lignin into hydrocarbons under mild conditions
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The one-pot conversion of lignin biomass into high-grade hydrocarbon biofuels via catalytic hydrodeoxygenation (HDO) holds significant promise for renewable energy. A great challenge for this route involves developing efficient non-noble metal catalysts to obtain a high yield of hydrocarbons under relatively mild conditions. Herein, a high-performance catalyst has been prepared via the in situ reduction of Ni phyllosilicate-like nanosheets (Ni-PS) synthesized by a reduction-oxidation strategy at room temperature. The Ni-PS precursors are partly converted into Ni0 nanoparticles by in situ reduction and the rest remain as supports. The Si-containing supports are found to have strong interactions with the nickel species, hindering the aggregation of Ni0 particles and minimizing the Ni0 particle size. The catalyst contains abundant surface defects, weak Lewis acid sites and highly dispersed Ni0 particles. The catalyst exhibits excellent catalytic activity towards the depolymerization and HDO of the lignin model compound, 2-phenylethyl phenyl ether (PPE), and the enzymatic hydrolysis of lignin under mild conditions, with 98.3% cycloalkane yield for the HDO of PPE under 3 MPa H2 pressure at 160 °C and 40.4% hydrocarbon yield for that of lignin under 3 MPa H2 pressure at 240 °C, and its catalytic activity can compete with reported noble metal catalysts.
- Cao, Meifang,Chen, Bo,He, Chengzhi,Ouyang, Xinping,Qian, Yong,Qiu, Xueqing
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supporting information
p. 846 - 857
(2022/02/09)
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- Ru/hydroxyapatite as a dual-functional catalyst for efficient transfer hydrogenolytic cleavage of aromatic ether bonds without additional bases
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Cleavage of aromatic ether bonds is a key step for lignin valorization, and the development of novel heterogeneous catalysts with high activity is crucial. Herein, bifunctional Ru/hydroxyapatite has been prepared via ion exchange and subsequent reduction. The obtained Ru/hydroxyapatite could efficiently catalyze the cleavage of various compounds containing aromatic ether bonds via transfer hydrogenolysis without additional bases. Systematic studies indicated that the basic nature of hydroxyapatite and electron-enriched Ru sites resulted in the high activity of the catalyst. A mechanism study revealed that the direct cleavage of aromatic ether bonds was the main reaction pathway.
- Hua, Manli,Song, Jinliang,Xie, Chao,Wu, Haoran,Hu, Yue,Huang, Xin,Han, Buxing
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p. 5073 - 5079
(2019/09/30)
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- Titanium(III)-Oxo Clusters in a Metal-Organic Framework Support Single-Site Co(II)-Hydride Catalysts for Arene Hydrogenation
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Titania (TiO2) is widely used in the chemical industry as an efficacious catalyst support, benefiting from its unique strong metal-support interaction. Many proposals have been made to rationalize this effect at the macroscopic level, yet the underlying molecular mechanism is not understood due to the presence of multiple catalytic species on the TiO2 surface. This challenge can be addressed with metal-organic frameworks (MOFs) featuring well-defined metal oxo/hydroxo clusters for supporting single-site catalysts. Herein we report that the Ti8(μ2-O)8(μ2-OH)4 node of the Ti-BDC MOF (MIL-125) provides a single-site model of the classical TiO2 support to enable CoII-hydride-catalyzed arene hydrogenation. The catalytic activity of the supported CoII-hydride is strongly dependent on the reduction of the Ti-oxo cluster, definitively proving the pivotal role of TiIII in the performance of the supported catalyst. This work thus provides a molecularly precise model of Ti-oxo clusters for understating the strong metal-support interaction of TiO2-supported heterogeneous catalysts.
- Ji, Pengfei,Song, Yang,Drake, Tasha,Veroneau, Samuel S.,Lin, Zekai,Pan, Xiandao,Lin, Wenbin
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p. 433 - 440
(2018/01/17)
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- Pyridine(diimine) Molybdenum-Catalyzed Hydrogenation of Arenes and Hindered Olefins: Insights into Precatalyst Activation and Deactivation Pathways
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Pyridine(diimine) molybdenum bis(olefin) and bis(alkyl) complexes were synthesized, characterized, and examined for their catalytic activity in the hydrogenation of benzene and a selection of substituted arenes. The molybdenum bis(alkyl) complex (4-tBu-iPrPDI)Mo(CH2SiMe3)2 (iPrPDI = 2,6-(2,6-(C(CH3)2H)2C6H3N=CMe)2C5H3N) exhibited the highest activity for the hydrogenation of benzene, producing cyclohexane in >98% yield at 23 °C under 4 atm of hydrogen after 48 h. Toluene and o-xylene were similarly hydrogenated to their respective cycloalkanes, with the latter yielding predominantly (79:21 dr) cis-1,2-dimethylcyclohexane. The molybdenum-catalyzed hydrogenation of naphthalene yielded tetralin exclusively, and this selectivity was maintained at higher H2 pressure. At 32 atm of H2, more hindered arenes such as monosubstituted benzenes, biphenyl, and m- and p-xylenes underwent hydrogenation with yields ranging between 20 and >98%. (4-tBu-iPrPDI)Mo(CH2SiMe3)2 was also a competent alkene hydrogenation catalyst, supporting stepwise reduction of benzene to cyclohexadiene and cyclohexene during molybdenum-catalyzed arene hydrogenation. Deuterium labeling studies for the molybdenum-catalyzed hydrogenation of benzene produced numerous isotopologues and stereoisomers of cyclohexane, indicating reversible hydride (deuteride) insertion/β-H(D) elimination, diene/olefin binding, and allylic C-H(D) activation during the reaction. The resting state of the catalyst under neat conditions was established as the η6-benzene complex (iPrPDI)Mo(η6-benzene). Under catalytic conditions, pyridine underwent C-H activation of the 2-position and furan underwent formal C-O oxidative addition to yield a "metallapyran". Both reactions were identified as important catalyst deactivation pathways for the attempted molybdenum-catalyzed hydrogenation of heteroarenes.
- Joannou, Matthew V.,Bezdek, Máté J.,Chirik, Paul J.
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p. 5276 - 5285
(2018/05/15)
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- Effect of the Crystallographic Phase of Ruthenium Nanosponges on Arene and Substituted-Arene Hydrogenation Activity
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Identifying crystal structure sensitivity of a catalyst for a particular reaction is an important issue in heterogeneous catalysis. In this context, the activity of different phases of ruthenium catalysts for benzene hydrogenation has not yet been investigated. The synthesis of hcp and fcc phases of ruthenium nanosponges by chemical reduction method has been described. Reduction of ruthenium chloride using ammonia borane (AB) and tert-butylamine borane (TBAB) as reducing agents gave ruthenium nanosponge in its hcp phase. On the other hand, reduction using sodium borohydride (SB) afforded ruthenium nanosponge in its fcc phase. The as prepared hcp ruthenium nanosponge was found to be catalytically more active compared to the as prepared fcc ruthenium nanosponge for hydrogenation of benzene. The hcp ruthenium nanosponge was found to be thermally stable and recyclable over several cycles. This self-supported hcp ruthenium nanosponge shows excellent catalytic activity towards hydrogenation of various substituted benzenes. Moreover, the ruthenium nanosponge catalyst was found to bring about selective hydrogenation of aromatic cores of phenols and aryl ethers to the respective alicyclic products without hydrogenolysis of the C?O bond.
- Ghosh, Sourav,Jagirdar, Balaji R.
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p. 3086 - 3095
(2018/05/29)
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- Polysilane-Immobilized Rh-Pt Bimetallic Nanoparticles as Powerful Arene Hydrogenation Catalysts: Synthesis, Reactions under Batch and Flow Conditions and Reaction Mechanism
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Hydrogenation of arenes is an important reaction not only for hydrogen storage and transport but also for the synthesis of functional molecules such as pharmaceuticals and biologically active compounds. Here, we describe the development of heterogeneous Rh-Pt bimetallic nanoparticle catalysts for the hydrogenation of arenes with inexpensive polysilane as support. The catalysts could be used in both batch and continuous-flow systems with high performance under mild conditions and showed wide substrate generality. In the continuous-flow system, the product could be obtained by simply passing the substrate and 1 atm H2 through a column packed with the catalyst. Remarkably, much higher catalytic performance was observed in the flow system than in the batch system, and extremely strong durability under continuous-flow conditions was demonstrated (>50 days continuous run; turnover number >3.4 × 105). Furthermore, details of the reaction mechanisms and the origin of different kinetics in batch and flow were studied, and the obtained knowledge was applied to develop completely selective arene hydrogenation of compounds containing two aromatic rings toward the synthesis of an active pharmaceutical ingredient.
- Miyamura, Hiroyuki,Suzuki, Aya,Yasukawa, Tomohiro,Kobayashi, Shu
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supporting information
p. 11325 - 11334
(2018/09/06)
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- Upgrading of aromatic compounds in bio-oil over ultrathin graphene encapsulated Ru nanoparticles
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Fast pyrolysis of biomass for bio-oil production is a direct route to renewable liquid fuels, but raw bio-oil must be upgraded in order to remove easily polymerized compounds (such as phenols and furfurals). Herein, a synthesis strategy for graphene encapsulated Ru nanoparticles (NPs) on carbon sheets (denoted as Ru@G-CS) and their excellent performance for the upgrading of raw bio-oil were reported. Ru@G-CS composites were prepared via the direct pyrolysis of mixed glucose, melamine and RuCl3 at varied temperatures (500-800 °C). Characterization indicated that very fine Ru NPs (2.5 ± 1.0 nm) that were encapsulated within 1-2 layered N-doped graphene were fabricated on N-doped carbon sheets (CS) in Ru@G-CS-700 (pyrolysis at 700 °C). And the Ru@G-CS-700 composite was highly active and stable for hydrogenation of unstable components in bio-oil (31 samples including phenols, furfurals and aromatics) even in aqueous media under mild conditions. This work provides a new protocol to the utilization of biomass, especially for the upgrading of bio-oil.
- Shi, Juanjuan,Zhao, Mengsi,Wang, Yingyu,Fu, Jie,Lu, Xiuyang,Hou, Zhaoyin
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supporting information
p. 5842 - 5848
(2016/05/24)
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- Selective Hydrodeoxygenation of Lignin-Derived Phenols to Cyclohexanols or Cyclohexanes over Magnetic CoNx@NC Catalysts under Mild Conditions
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The hydrodeoxygenation (HDO) of lignin-derived phenols is important to produce the renewable biofuels. Herein, we reported a simple method to prepare magnetic nitrogen-doped carbon supported cobalt nitride catalysts (CoNx@NC) by copyrolysis of cellulose and cobalt nitrate under ammonia atmosphere. The catalysts were prepared at different temperatures and characterized by elemental analysis, atomic absorption spectroscopy (AAS), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and temperature-programmed reduction (TPR). The CoNx@NC-650 (pyrolyzed at 650°C) exhibited the best HDO activity for eugenol conversion among a series of Co-based catalysts. The yield of propylcyclohexanol from eugenol was >99.9% under 2 MPa H2 at 200°C for 2 h. Moreover, a high yield of propylcyclohexane (99.1%) could be achieved when the solid acid HZSM-5 was added to the reaction system. Other lignin-derived phenolic compounds were also investigated and the yield of alkanes was >90%. Based on the mechanism investigation, the catalyst demonstrated a high selectivity to cleave the Caryl-OR bond under mild conditions. (Chemical Equation Presented).
- Liu, Xiaohao,Xu, Lujiang,Xu, Guangyue,Jia, Wenda,Ma, Yanfu,Zhang, Ying
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p. 7611 - 7620
(2016/11/17)
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- Nickel-tungsten sulfide aromatic hydrocarbon hydrogenation catalysts synthesized in situ in a hydrocarbon medium
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Nickel-tungsten sulfide nanocatalysts for the hydrogenation of aromatic hydrocarbons (HCs) have been prepared by the in situ decomposition of a nickel thiotungstate precursor in a HC feedstock using 1-butyl-1-methylpiperidinium nickel thiotungstate complex [BMPip]2Ni[WS4]2 as the precursor. The in situ synthesized particles have been characterized by X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. It has been shown that the resulting Ni-W-S particles are nanoplates associated in multilayer agglomerates; the average length of the Ni-W-S particles is 6 nm; the average number of layers in the multilayer packaging is three. The catalytic activity of the synthesized catalysts has been studied in the hydrogenation of model mixtures of mono- and bicyclic aromatic HCs and in the conversion of dibenzothiophene in a batch reactor at a temperature of 350°C and a hydrogen pressure of 5.0 MPa. It has been shown that the studied catalysts can be used for the hydrofining of light cycle oil.
- Sizova,Serdyukov,Maksimov
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p. 470 - 480
(2015/11/23)
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- Selective hydrogenolysis of phenols and phenyl ethers to arenes through direct C-O cleavage over ruthenium-tungsten bifunctional catalysts
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Direct hydrogenolysis of the aromatic Csp2-O bonds in both phenols and phenyl ethers to form arenes selectively is a core enabling technology that can expand greatly the scope of chemical manufacture from biomass. However, conventional hydrogenolysis of phenols typically led to aromatic ring saturation instead of the cleavage of the Csp2-O bonds. Herein, we report a recyclable Ru-WOx bifunctional catalyst that showed high catalytic activities for the hydrogenolysis of a wide range of phenols and phenyl ethers, including dimeric lignin model compounds and the primitive phenols separated from pyrolysis lignin, to form arenes selectively in water. Preliminary mechanistic studies supported that the reactions occurred via a direct cleavage of the Csp2-O bonds and the concerted effects of the hydrogenating Ru sites and the Lewis acidic W sites are the key to such an unusual reactivity.
- Huang, Yao-Bing,Yan, Long,Chen, Meng-Yuan,Guo, Qing-Xiang,Fu, Yao
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p. 3010 - 3017
(2015/05/27)
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- Catalytic hydrogenation of aromatic rings catalyzed by Pd/NiO
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A simple and efficient heterogeneous palladium catalyst was prepared for aromatic ring hydrogenation. The catalyst was prepared by a reduction-deposition method and exhibited high activity and selectivity for the hydrogenation of a variety of substituted aromatic compounds to the corresponding cyclohexane and cyclohexanol derivatives with up to 99% yields. The catalyst was characterized by BET, TEM, XRD, XPS and ICP. Meanwhile the reusability of the catalyst was investigated, and it can be reused for several runs without significant deactivation.
- Wang, Yanan,Cui, Xinjiang,Deng, Youquan,Shi, Feng
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p. 2729 - 2732
(2014/01/06)
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- CO2 promoted hydrogenolysis of benzylic compounds in methanol and water
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This study successfully demonstrated the hydrogenolysis of benzylic alcohols and their derivatives over a Pd/C catalyst by using CO 2-expanded methanol (CX-methanol) and compressed CO2/water as two green reaction media. It was found that with the addition of low-pressure CO2 (1 MPa), the reaction conversions of benzylic alcohols and their derivatives could all be increased in the CO2 promoted systems. For example, the conversion of 1-phenylethanol could be elevated from 23% to 63% in CX-methanol and the conversion of benzyl alcohol could be elevated from 75% to 92% in compressed CO2/water. The positive effects of CO2 could be attributed to the decrease of mass transfer resistance and the increase of hydrogen solubility. CO2 could also form methylcarbonic acid and carbonic acid in methanol and water, respectively. Therefore, it could enhance the departing ability of the protonated hydroxyl leaving groups by providing a more acidic environment. In addition, the hydrogenolysis (or deoxygenation) of aromatic aldehyde and ketone by using compressed CO2/water as the solvent were also studied in this work. The results suggested that both CX-methanol and compressed CO 2/water could be used as two efficient solvents for the hydrogenolysis reactions.
- Lin, Hsin-Wei,Yen, Clive H.,Hsu, Han,Tan, Chung-Sung
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p. 17222 - 17227
(2013/09/24)
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- Moving from surfactant-stabilized aqueous rhodium (0) colloidal suspension to heterogeneous magnetite-supported rhodium nanocatalysts: Synthesis, characterization and catalytic performance in hydrogenation reactions
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Wet impregnation of pre-synthesized surfactant-stabilized aqueous rhodium (0) colloidal suspension on silica was employed in order to prepare supported Rh0 nanoparticles of well-defined composition, morphology and size. A magnetic core-shell support of silica (Fe3O4@SiO 2) was used to increase the handling properties of the obtained nanoheterogeneous catalyst. The nanocomposite catalyst Fe3O 4@SiO2-Rh0 NPs was highly active in the solventless hydrogenation of model olefins and aromatic substrates under mild conditions with turnover frequencies up to 143,000 h-1. The catalyst was characterized by various transmission electron microscopy techniques showing well-dispersed rhodium nanoparticles (~3 nm) mainly located at the periphery of the silica coating. The heterogeneous magnetite-supported nanocatalyst was investigated in the hydrogenation of cyclohexene and compared to the previous surfactant-stabilized aqueous Rh0 colloidal suspension and various silica-supported Rh0 nanoparticles. Finally, the composite catalyst could be reused in several runs after magnetic separation.
- Pélisson, Carl-Hugo,Vono, Lucas L.R.,Hubert, Claudie,Denicourt-Nowicki, Audrey,Rossi, Liane M.,Roucoux, Alain
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experimental part
p. 124 - 129
(2012/06/18)
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- Kinetic analysis of 4-isopropylphenol hydrogenation over activated carbon-supported rhodium catalysts in supercritical carbon dioxide solvent
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Hydrogenation behavior of 4-isopropylphenol to 4-isopropylcyclohexanol over activated carbon-supported rhodium catalysts in supercritical carbon dioxide (scCO2) at 313 K was studied in a batch reactor and the results were compared with those in 2-propanol. Higher yields of cis-4-isopropylcyclohexanol were obtained in scCO2 than in 2-propanol, and the formation of a byproduct, isopropylcyclohexane, was suppressed in scCO2. The catalyst modification with hydrochloric or phosphoric acid enhanced the yield of cis-4-isopropylcyclohexanol in both scCO2 and 2-propanol solvents. Kinetic analyses of the reaction profiles revealed higher reaction rates in scCO2 than those in 2-propanol for the 4-isopropylcyclohexanol formation both by the direct hydrogenation of 4-isopropylphenol and by the consecutive hydrogenation of 4-isopropylcyclohexanone, and also revealed that the addition of hydrochloric acid increased the consecutive hydrogenation rate of 4-isopropylcyclohexanone to cis-4-isopropylcyclohexanol, which reduced the total reaction time needed for the complete hydrogenation of 4-isopropylphenol to 4-isopropylcyclohexanol. The Royal Society of Chemistry 2012.
- Hiyoshi, Norihito,Sato, Osamu,Yamaguchi, Aritomo,Rode, Chandrashekhar V.,Shirai, Masayuki
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experimental part
p. 633 - 638
(2012/05/04)
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- Facile sonochemical synthesis of carbon nanotube-supported bimetallic Pt-Rh nanoparticles for room temperature hydrogenation of arenes
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Bimetallic Pt-Rh nanoparticles can be deposited uniformly on surfaces of carboxylate functionalized multi-walled carbon nanotubes (MWNTs) using a simple one-step sonochemical method. The bimetallic nanoparticle catalyst exhibits a strong synergistic effect relative to the individual Pt or Rh metal nanoparticles for catalytic hydrogenation of polycyclic aromatic hydrocarbons (PAHs), neat benzene and alkylbenzenes. Complete ring saturation of PAHs can be achieved using the bimetallic Pt-Rh/MWNTs catalyst at room temperature. This one-step synthesis technique provides a simple and rapid way of making highly active and recyclable CNT-supported monometallic and bimetallic nanocatalysts for low temperature hydrogenation reactions.
- Pan, Horng-Bin,Wai, Chien M.
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scheme or table
p. 1649 - 1660
(2011/10/08)
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- Dehalogenation and hydrogenation of aromatic compounds catalyzed by nanoparticles generated from rhodium bis(imino)pyridine complexes
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Chloro[2,6-bis{1-(phenyl)iminoethyl}pyridine]rhodium(I) complexes (RhCl(N,N,N); 1-11) have been prepared by reaction of the dimer [Rh(μ-Cl)(η2-C2H4)2] 2 with the corresponding nitrogen donor ligand. These complexes afford nanoparticles with a mean diameter of 1.5 ± 0.2 nm stabilized by the partially hydrogenated ligand, under 1 atm of hydrogen, in 2-propanol as solvent, at 60 °C, and in the presence of KtBuO. Under a constant atmospheric pressure of hydrogen, the nanoparticles catalyze the dehalogenation of the chlorobenzene 1,2-, 1,3-, and 1,4-dichlorobenzene, 1,2,4- trichlorobenzene, fluorobenzene, 2-, 3-, and 4-chlorobiphenyl, and 4,4′- and 3,5-dichlorobiphenyl and the hydrogenation of benzene, toluene, p-xylene, styrene, α-methylstyrene, biphenyl, aniline, phenol, and pyridine. A Hg(0) poisoning test reveals that homogeneous and heterogeneous catalysis coexist during the dehalogenation reactions, whereas the hydrogenation processes are heterogeneous. The nanoparticles can be also generated in the presence of basic aluminum oxide of 150 mesh, which at the same time acts as a support. When they are deposited on the alumina, the nanoparticles do not significantly modify their catalytic activity.
- Buil, Maria L.,Esteruelas, Miguel A.,Niembro, Sandra,Olivan, Montserrat,Orzechowski, Lars,Pelayo, Cristina,Vallribera, Adelina
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experimental part
p. 4375 - 4383
(2011/01/03)
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- Synthesis of bipyridine-stabilized rhodium nanoparticles in non-aqueous ionic liquids: A new efficient approach for arene hydrogenation with nanocatalysts
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A new approach to stabilize metal nanoparticles with polynitrogen ligands in ionic liquids (ILs) is described. Zerovalent metal nanospecies in the size range of 2.0 nm were easily prepared in various ionic liquids by chemical reduction of a rhodium salt with an excess amount of sodium borohydride (NaBH4) and efficiently stabilized by 2,2′-bipyridine. The influence of the bipyridine ratio in various ILsaccording to the nature of the cation-anion association was investigated. These nanocatalysts were evaluated in the hydrogenation of aromatic compounds in ILs under various catalytic conditions (P=1-40 bar, T=20-80 °C).
- Leger, Bastien,Denicourt-Nowicki, Audrey,Roucoux, Alain,Olivier-Bourbigou, Helene
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scheme or table
p. 153 - 159
(2009/04/08)
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- Nanoheterogeneous catalytic hydrogenation of arenes: Evaluation of the surfactant-stabilized aqueous ruthenium(O) colloidal suspension
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The hydrogenation of various aromatic compounds by a surfactant-stabilized aqueous ruthenium(O) colloidal suspension was investigated. The nanocatalysts in the size range of 2.5-3.5 nm were synthesized by reducing ruthenium trichloride salt with sodium borohydride and were stabilized by the highly water soluble N,N-dimethyl-N-cetyl-N-(2-hydroxyethyl)ammonium chloride salt according to our classical approach. The efficient catalytic reactions were performed at room temperature and under hydrogen pressure. The effect of the stirring, namely magnetic stir bar or gas projection impeller, was also studied. A comparison with an analogous rhodium nanocatalyst is described.
- Nowicki, Audrey,Boulaire, Virginie Le,Roucoux, Alain
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p. 2326 - 2330
(2008/09/18)
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- A simple and reproducible method for the synthesis of silica-supported rhodium nanoparticles and their investigation in the hydrogenation of aromatic compounds
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Colloidal suspensions of rhodium nanoparticles have been easily prepared in aqueous solution by chemical reduction of the precursor RhCl 3·3H2O in the presence of the surfactant N,N-dimethyl-N-cetyl-N-(2-hydroxyethyl)ammonium chloride (HEA16Cl) and further used to immobilize rhodium nanoparticles on silica by simple impregnation. The obtained silica-supported rhodium nanoparticles have been investigated by adapted characterization methods such as transmission electron microscopy and X-ray photoelectron spectroscopy. A particle size increase from 2.4 to 5 nm after the silica immobilization step and total elimination of the surfactant has been observed. This "heterogeneous" catalyst displayed good activities for the hydrogenation of mono-, di- alkylsubstituted and/or functionalized aromatic derivatives in water under atmospheric hydrogen pressure and at room temperature. In all cases, the catalyst could be recovered several times after a simple decantation or filtration and reused without any significant loss in catalytic activity. This supported catalyst has also been tested under higher hydrogen pressure giving rise to TOFs reaching 6430 h -1 at 30 bar and in terms of catalytic lifetime 30 000 TTO in 8.5 h for pure anisole hydrogenation at 40 bar. the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006.
- Mevellec, Vincent,Nowicki, Audrey,Roucoux, Alain,Dujardin, Christophe,Granger, Pascal,Payen, Edmond,Philippot, Karine
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p. 1214 - 1219
(2007/10/03)
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- PROCESS FOR PRODUCING CUMENE AND PROCESS FOR PROPYLENE OXIDE PRODUCTION INCLUDING THE PRODUCTION PROCESS
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A process for producing cumene by subjecting cumyl alcohol to hydrogenolysis or hydrogenation subsequent to dehydration, which comprises using a palladium-based catalyst as a catalyst for the hydrogenolysis or the hydrogenation, and using hydrogen having a carbon monoxide concentration of 0.1 to 10 % by volume as hydrogen.
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Page/Page column 6
(2008/06/13)
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- PROCESS FOR PRODUCING ALKYLENE OXIDE
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A process for preparing an alkylene oxide, which process comprises: (i) oxidizing an alkylebenzene to obtain a stream comprising alkylbenzene hydroperoxide; (ii) contacting at least part of the alkylbenzene hydroperoxide obtained in step (i) with an olefin to obtain a product stream comprising an alkylene oxide; (iii) separating alkylene oxide compound from the product stream of step (ii) to obtain (a) a residual product stream comprising alkylphenyl alcohol, and (b) alkylene oxide; (iv) feeding at least a part of the residual product stream comprising alkylphenyl alcohol to a reactor having a catalytic distillation zone, and concurrently in the reactor: (a) contacting the residual product stream comprising alkylphenyl alcohol with hydrogen in the catalytic distillation zone to convert the alkylphenyl alcohol in the residual product stream to alkylbenzene and from a reaction mixture; and, (b) separating alkylbenze from the reaction mixture by fraction distillation; (v) withdrawing a stream comprising alkybenzene and having a reduced concentration of alkylphenyl alcohol than the feed stream from the reactor at a position upper from the catalytic reaction zone; withdrawing from the reactor at a position lower than the catalytic distillation zone a bottom stream comprising dimer(s) of alkylbenzene; alkylbenze; and. (viii) recycling at least a part of the alkylbenzene produced from (iv)(b) and/or (vi) to step (i).
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Page/Page column 24; 25
(2008/06/13)
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- PROCESS FOR PRODUCING ALKYLBENZENE
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A process for producing an alkylbenzene from an alkylphenyl alcohol comprising the steps of: (a) feeding a feed stream comprising alkylphenyl a reactor having a catalytic distillation zone; and, (b) concurrently in the reactor (i) contacting the feed stream comprising alkylphenyl alcohol with hydrogen in the catalytic distillation zone to convert alkylphenyl alcohol to alkylbenzene over a catalyst comprising Group VIII or a Group IB metal; and, (ii) separating alkylbenzene from the reaction mixture by fractional distillation to produce an overhead stream comprising alkylbenzene having a reduced concentration of alkylphenyl alcohol than the feed stream from the distillation column reactor. Examples of the alkylphenyl alcohol include cumyl alcohol, phenyl ethyl alcohol, or di(2-hydroxyl 2-propyl)benzene, and that for the alkylbenzene include cumene and di-ethyl benzene, or di(2-hydroxyl-2-propyl) benzene.
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(2010/02/10)
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- HYDROCRAKING OF DIPHENYLALKANES
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A hydrocracking process comprises the steps of reacting a diphenyl alkane having a formulation of RIR2C(Ph)-(C)n(H)m-C(Ph)R3R4 with hydrogen using a catalyst comprising a metal selected from the group consisting of Group IB and Group VIII metal compounds, preferably on an acidic support, to produce alkylbenzene(s) having a structure of RIR2C(Ph)R5 and R6(Ph)CR3R4; wherein the total number of carbon atoms for R5 and R6 is equal to n; wherein R1, R2, R3, R4 each is a H or a hydrocarbon group having 1-10 carbon atoms.
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Page/Page column 9-10
(2008/06/13)
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- Alkylation of alkenes: Ethylaluminum sesquichloride-mediated hydro-alkyl additions with alkyl chloroformates and di-tert-butylpyrocarbonate
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A general method for the hydro-alkyl addition to the nonactivated C=C double bond of alkenes using alkyl chloroformates (primary, secondary), 12, and di-tert-butylpyrocarbonate, 52, mediated by ethylaluminum sesquichloride (Et3Al2Cl3) has been developed. Reaction of 12 and 52, respectively, with Et3Al2Cl3 gives an alkyl cation which is added to the alkene; hydride transfer to the adduct carbenium ion or, if applicable, 1,2-H shift followed by hydride transfer from Et3Al2Cl3 to the rearranged adduct carbenium ion gives the saturated addition product. The reaction has been applied to 1-alkenes, 2-methyl-1-alkenes, internal double bonds, and to three cyclic alkenes. Special interest has been focused on alkylations of unsaturated fatty compounds, such as oleic acid (2), which are important renewable feedstocks. 2-Methylalkanes, 3-methylalkanes, 2,4-dimethylalkanes, 2,3-dimethylalkanes, 2,2,4-trimethylalkanes, cyclohexylalkanes, and carboxylic acids and esters with the respective branched alkyl chain have been synthesized with good to moderate yields.
- Biermann, Ursula,Metzger, Juergen O.
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p. 10319 - 10330
(2007/10/03)
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- Minor Modifications to the Ligands Surrounding a Ruthenium Complex Lead to Major Differences in the Way in which they Catalyse the Hydrogenation of Arenes
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The hydrogenation of benzene and other arenes under aqueous-organic biphasic conditions is evaluated using the ruthenium complexes Ru(η 6-C10H14)(pta)Cl2 (pta = 1,3,5-triaza-7-phosphaadamantane), Ru(η6-C10H 14)(tppts)Cl2 (tppts = tris-3-sulfonatophenylphosphine trisodium salt) and [Ru(η6-C10H14)(pta) 2Cl]+. The active catalysts formed during the hydrogenations correspond to a trinuclear cluster, a colloid and a mononuclear complex, respectively.
- Dyson, Paul J.,Ellis, David J.,Laurenczy, Gábor
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p. 211 - 215
(2007/10/03)
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- Arene Hydrogenation with a Stabilised Aqueous Rhodium(0) Suspension: A Major Effect of the Surfactant Counter-Anion
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A reduced aqueous colloidal suspension of rhodium shows an efficient activity in the catalytic hydrogenation of various benzene derivatives under biphasic conditions at room temperature and under atmospheric hydrogen pressure. The rhodium nanoparticles in the size range of 2-2.5 nm have been synthesised by reducing RhCl3 · 3 H2O with sodium borohydride and were stabilised by highly water-soluble N,N-dimethyl-N-cetyl-N-(2- hydroxyethyl)ammonium salts (HEA16X, X = Br, Cl, I, CH3SO 3, BF4). The major influence of the counter-ion of these surfactants on catalytic activity and recycling is described. The best results have been obtained with chloride ammonium salts HEA16Cl.
- Roucoux, Alain,Schulz, Jürgen,Patin, Henri
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p. 222 - 229
(2007/10/03)
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- Catalytic hydrogenation of aromatics under biphasic conditions: Isolation and structural characterisation of the cluster intermediate [(η6-C6Me6)2(η 6-C6H6)Ru3(μ2-H) 2(μ2-OH)(μ3-O)]+
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The water-soluble cluster cation [(η6-C6Me6)2(η 6-C6H6)Ru3(μ2-H) 3(μ3-O)]+ (2) catalyses the hydrogenation of benzene and benzene derivatives to give the corresponding cyclohexanes under biphasic conditions. The catalytic activity of 2 depends markedly on the substrate, an extremely high activity being observed for ethylbenzene. The cationic species present in the catalytic mixture of the ethylbenzene hydrogenation could be isolated as the tetrafluoroborate salt and characterised as the cation [(η6-C6Me6)2(η 6-C6H6)Ru3(μ2-H) 2(μ2-OH)(μ3-O)]+ (3). With 3 as the catalyst, the catalytic activity is also much higher for other benzene derivatives.
- Faure, Matthieu,Vallina, Ana Tesouro,Stoeckli-Evans, Helen,Süss-Fink, Georg
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p. 103 - 108
(2007/10/03)
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- Bimolecular chemistry of dimethylcarbene
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A new non-nitrogenous precursor of dimethylcarbene has been synthesized. Photolysis of 10,10′-dimethyltricyclo[4.3.1.01,6]deca-2,4-diene in solution with 254 nm light produces dimethylcarbene. Previously unknown intermolecular reactions of dimethylcarbene have been observed.
- Likhotvorik, Igor R.,Tippmann, Eric,Platz, Matthew S.
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p. 3049 - 3051
(2007/10/03)
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- Stabilized rhodium(0) nanoparticles: A reusable hydrogenation catalyst for arene derivatives in a biphasic water-liquid system
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A colloidal system based on an aqueous suspension of rhodium(0) nanoparticles proved to be an efficient catalyst for the hydrogenation of arene derivatives under biphasic conditions. The rhodium nanoparticles (2 - 2.5 nm) were synthesized by the reduction of RhCl3·3 H2O with sodium borohydride and were stabilized by highly water-soluble N-alkyl-N-(2- hydroxyethyl)ammonium salts (HEA-C(n)). These surfactant molecules were characterized by measurements of the surface tension and the aqueous dispersions with rhodium were observed by transmission electron cryomicroscopy. The catalytic system is efficient under ultramild conditions, namely room temperature and 1 atm H2 pressure. The aqueous phase which contains the protected rhodium(0) colloids can be reused without significant loss of activity. The microheterogeneous behavior of this catalytic system was confirmed on a mercury poisoning experiment.
- Schulz, Juergen,Roucoux, Alain,Patin, Henri
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p. 618 - 624
(2007/10/03)
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- Unprecedented efficient hydrogenation of arenes in biphasic liquid-liquid catalysis by re-usable aqueous colloidal suspensions of rhodium
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A reduced aqueous colloidal suspension of rhodium shows efficient activity for the catalytic hydrogenation of various benzene derivatives under biphasic conditions at room temperature and under atmospheric hydrogen pressure; the aqueous phase containing the Rh(0) particles can be re-used for further runs with a complete conservation of activity.
- Schulz, Juergen,Roucoux, Alain,Patin, Henri
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p. 535 - 536
(2007/10/03)
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- Friedel-Crafts alkylation of alkenes: Ethylaluminum sesquichloride induced alkylations with alkyl chloroformates
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The formal addition of propane to nonactivated double bonds can be achieved with isopropyl chloroformate (2) in the presence of Et3Al2Cl3. Thus, a 1:1 mixture of 10-isopropyloctadecanoic acid (3) and the 9- regioisomer is formed from oleic acid (1). The reaction may also be carried out with 1-alkenes by the addition of triethylsilane as a hydride donor.
- Biermann, Ursula,Metzger, Juergen O.
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p. 3675 - 3677
(2007/10/03)
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- Colloidal palladium, easily formed in organic solvents, is a highly active and stable catalyst for selective hydrogenations and dehydrohalogenations
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Collidal Pd formed in organic solvents from Pd(hfacac)2 and silane or an Si-H- containing polymer is an active, stable and selective catalyst for hydrogenation and dehydrohalogenation.
- Fowley, Lissa A.,Michos, Demetrius,Luo, Xiao-Liang,Crabtree, Robert H.
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p. 3075 - 3078
(2007/10/02)
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- Radical Cations of Cyclohexanes Alkyl-substituted on One Carbon: An ESR Study of the Jahn-Teller Distorted HOMO of Cyclohexane
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Cation radicals of cyclohexanes alkyl-substituted on one carbon have been stabilized in perfluoromethylcyclohexane and other halocarbon matrices at 4.2 K and studied by means of ESR spectroscopy.It was found that all have an electronic ground state resembling the 2Ag state of the cyclohexane cation, one of the possible states following a Jahn-Teller distortion of the D3d cyclohexane chair structure.The cations can be classified into two groups depending on the substituted alkyl group.To the first group belong the cations with a methyl group or a primary carbon (ethyl, n-propyl or isobutyl group) attached to the ring.The disubstituted cyclohexane cations of 1,1-dimethylcyclohexane and 1-methyl-1-ethylcyclohexane were also found to have a similar structure.The ESR spectra are characterized by a 1:2:1 three-line pattern with the hyperfine (hf) splitting due to two magnetically equivalent equatorial ring hydrogens.The magnitude of the splitting was found to depend on the size and number of substituents, ranging from 74 G (methylcyclohexane.+) to 55 G (isobutylcyclohexane.+).An additional doublet, 17-34 G, due to a hydrogen on the substituent could be detected in certain cases.Such hydrogens are axial with one of the elongated C-C bonds in the ring structure which contains a relatively large fraction of the unpaired electron.It follows that the substituents are located asymmetrically with respect to an ag-like SOMO in the ring.In the second group a secondary or tertiary carbon connects the substituent to the ring, such as an isopropyl or tert-butyl group.The largest hf splittings are ca. 30 G in magnitude, due to certain hydrogens on the substituent which are axial with respect to the cyclohexyl bond.It follows that an ag-like SOMO in the ring here is symmetrically arranged with respect to the position of the substituent.Hyperconjugation is the dominating mechanism for the spin transfer in all cations reported in this study.
- Shiotani, Masaru,Lindgren, Mikael,Ohta, Nobuaki,Ichikawa, Takahisa
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p. 711 - 719
(2007/10/02)
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- Hydrogenolysis of Small Cycloalkanes, X. - Catalytic Hydrogenation of Bicycloalkanes
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Dependent on n different products are obtained from bicycloalkanes by hydrogenation on Pt and Pd/C catalysts: from n = 5 onward only methylcycloalkanes of the same ring size; with n = 4 additionally 2-7 percent of cycloheptane is formed; with n = 3 ring enlargement increases to 5-20 percent and with n = 2 cyclopentane is the only product.Mainly butane is formed from bicyclobutane and no intermediate could be detected.Explanations are attempted.The expected products are produced on hydrogenation of methyl-substituted derivatives and spiroalkanes.
- Stahl, Karl-Johannes,Hertzsch, Winfried,Musso, Hans
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p. 1474 - 1484
(2007/10/02)
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- Ionization Energies and Entropies of Cycloalkanes. Kinetics of Free Energy Controlled Charge-Transfer Reactions.
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Enthalpies and entropies of ionization (ΔH0ion and ΔS0ion) of alkylcyclohexanes, as well as cycloheptane, cyclooctane, and trans-Decalin, have been determined by charge-transfer equilibrium measurements.Values of ΔHion, in units of kcal mol-1 (or eV), range from 229.6 (9.96) for cycloheptane to 210.7 (9.14) for trans-Decalin.A major effect of alkyl substitution is observed following substitution at a site α to a tertiary hydrogen atom (as from methylcyclohexane to 1,2-dimethylcyclohexane), or following replacement of a tertiary hydrogen atom (as from methylcyclohexane to 1,1-dimethylcyclohexane).In both cases, ΔH0 ion decreases by ca. 5 kcal mol-1.Entropies of ionization are near zero for alkylcyclohexanes but range up to 5 cal deg-1 mol-1 for nonsubstituted cycloalkanes (cyclooctane).The charge-transfer reactions involving the cycloalkanes are shown to be fast processes; i.e., the sum of the reaction efficiencies (r=k/kcollision) of the forward and reverse processes is near unity.The efficiencies of these processes appear to be determined uniquely by the overall free energy change (or equilibrium constant K).Specifically, the reaction efficiencies are defined, within a factor of 2 by the relation r=K/(1+K), which can be justified by using transition-state theory applied to the decomposition of a collision complex over surfaces lacking energy barriers.These reactions are defined as intrinsically fast processes in that they are slowed only by the overall reaction thermochemistry and not by any properties or reactions of the intermediate complex.
- Sieck, L. Wayne,Mautner, Michael
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p. 3646 - 3650
(2007/10/02)
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- Catalytic Hydrogenation of Aromatic Hydrocarbons. Stereochemical Definition of the Catalytic Cycle for η3-C3H5Co(P(OCH3)3)3
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The η3-C3H5Co(P(OCH3)3)3-catalyzed hydrogenations with D2of a series of unsaturated organic molecules, including cyclohexenes, cyclohexadienes, and arenes, have been investigated.Complete cis stereoselectivity was observed in the addition of deuterium to the unsaturated ring systems.When alkyl-substituted arenes were reduced with D2, the hydrogen atoms in the alkyl chains underwent H-D exchange as long as each successive carbon atom in the chain possessed at least one hydrogen atom.Hence, extensive H-D exchange occured in n-alkyl side chains while the tert-butyl side chain was deuterium free.When alkyl-substituted arenes were hydrogenated in the presence of olefins such as 1-hexene, a variety of isomeric alkylcyclohexenes and alkenylcyclohexanes were observed.The relative concentrations of these isomeric species provided information about the relative stabilities of the (olefin)cobalt species in the catalytic cycle.Further mechanistic information was obtained from other competitive reactions, i.e., hydrogenation reactions involving equimolar quantities of two different unsaturated molecules.The proposed initiation steps of the catalytic cycle have been revised on the basis of a study of η3-C8H13Co(P(OCH3)3)3 as a catalyst precursor.The cyclooctenyl-cobalt bond was cleaved by hydrogen early in the reaction, leaving the highly coordinately unsaturated hydride, HCo(P(OCH3)3)2, which is probably the true catalytic species.
- Bleeke, J. R.,Muetterties, E. L.
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p. 556 - 564
(2007/10/02)
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- APPLICATION OF 1H NMR AND 13C NMR FOR ESTABLISHING THE SPATIAL STRUCTURE OF STEREOISOMERIC o- AND p-MENTHANE, o- AND p-MENTHENES, AND ISOPROPYLCYCLOHEXANE.
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An attempt to establish the spatial structure of stereoisomeric o- and p-menthanes, 8-o- and 8-p-menthenes, and isopropylcyclohexane on the basis of an analysis of the **1H NMR and **1**3C NMR spectra is described.
- Bazyl'chik,Samitov,Ryabushkina
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p. 543 - 548
(2007/10/02)
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- THE PREPARATION OF HINDERED CUPRATES FROM ALDEHYDE TOSYLHYDRAZONES
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Copper reagents react with secondery and tertiary aldehyde tosylhydrazones to give unique, hindered cuprates which are alkylated in a one-flask procedure.
- Bertz, Steven H.
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p. 3151 - 3154
(2007/10/02)
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