- Role of hydrogenolysis and nucleophilic substitution in hydrodenitrogenation over sulfided NiMo/γ-Al2O3
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The HDS of cyclohexanethiol and 2-methylcyclohexanethiol was studied over a sulfided NiMO/γ-Al2O3 catalyst. About 66% of the thiols reacted by elimination to (methyl)cyclohexene and 33% by hydrogenolysis of the C-S bond to (methyl)cyclohexane. These values were slightly lower than those for the selectivity to methylcyclohexene and slightly higher than those for the selectivity to methylcyclohexane in the HDN of 2-methylcyclohexylamine. HDN occurred predominantly in aliphatic molecules that contained H atoms in the β position relative to the nitrogen atom by elimination of ammonia. Part of the remaining HDN occurred by nucleophilic substitution of the amine by H2S, followed by elimination of H2S from the resulting thiol and, to a lesser extent, by C-S bond hydrogenolysis, the rest of the remaining HDN occurred by direct hydrogenolysis of the C-N bond.
- Prins,Rota
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- Influence of noble metals (Pd, Pt) on the performance of Ru/Al2O3 based catalysts for toluene hydrogenation in liquid phase
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Catalytic hydrogenation of aromatic compounds is of great interest due to environmental aspects and the wide range of industrial processes involving such reaction. In this context, the present work aims to study the influence of Pd or Pt addition on the performance of Ru/Al2O3 based catalysts for toluene hydrogenation in liquid phase. For this, catalysts were prepared by wet impregnation from chlorinated precursors and reduced in liquid phase by formaldehyde (H2CO). After impregnation, a part of the catalysts were activated ex situ at 573?K or in situ at 523?K under H2. The studied solids were characterized by N2 physisorption, SEM?+?EDX, TEM, XPS and TPR techniques. Catalytic tests were conducted in a slurry Parr reactor at 373?K under constant H2 pressure of 5?MPa. Results show that solids reduction by H2CO led to metallic species, while the activation treatments form oxides and decrease the catalytic activity. The initial reaction rate of non-activated monometallic catalysts follows the order: Ru/Al2O3???Pd/Al2O3?≈?Pt/Al2O3. A synergistic effect on the activity of Ru/Al2O3 based catalysts is induced by the Pt addition.
- Suppino, Raphael Soeiro,Landers, Richard,Cobo, Antonio José Gomez
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- Kinetics and mechanism of unimolecular heterolysis of cage-like compounds: XIX. Effect of the nucleofuge nature on the activation parameters of heterolysis of 1-halo-1-methylcyclohexanes in cyclohexane. Heterolysis rate ratio in aprotic and protic solvents
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Heterolysis of 1-bromo-1-methylcyclohexane in cyclohexane (E1 reaction) involves solvation of the transition state (ΔS≠ = -81 J mol-1K-1), while heterolysis of 1-chloro-1- methylcyclohexane is characterized by desolvation of the transition state (ΔS≠ = 92 J mol-1K-1). The probability for the formation of transition state (interaction between cationoid intermediate and solvent cavity) increases in the first case due to enhanced stability of the solvated intermediate, and in the second, due to reduction in its size. The bromide/chloride heterolysis rate ratio decreases as the ionizing power of aprotic solvent decreases and that of protic solvent increases.
- Dvorko,Koshchii,Ponomareva
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- Kinetic investigation of the effect of nickel and fluorine on the HDN of methylcyclohexylamine over WS2/Al2O3 catalysts
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The effects of incorporation of nickel and fluorine in WS2/Al2O3 catalysts on the kinetics of the hydrodenitrogenation of methylcyclohexylamine were investigated. The catalysts were prepared from ammonium tetrathiotungstat
- Sun, Mingyong,Prins, Roel
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- Synergy of Ru and Ir in the Electrohydrogenation of Toluene to Methylcyclohexane on a Ketjenblack-Supported Ru-Ir Alloy Cathode
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An organic hydride system based on hydrogenation/dehydrogenation of toluene (TL)/methylcyclohexane (MCH) has been studied as a hydrogen storage technology. Electrohydrogenation of TL to MCH using a proton exchange membrane (PEM) electrolyzer is proposed as a candidate for the hydrogenation of TL in the organic hydride system. Recently, we reported that a Ketjenblack-supported Ru-Ir alloy (Ru-Ir/KB) cathode was effective for the reaction; however, electrohydrogenation mechanisms and catalyses of Ru and Ir in the electrohydrogenation have been unclear. In this paper, detailed characterization studies using transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS), and electrochemical studies using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) for hydrogen evolution and kinetic studies for catalytic hydrogenation of TL by Ru-Ir/KB catalysts were conducted. On the basis of the experimental results, the electrohydrogenation mechanisms and synergy of Ru and Ir were proposed.
- Inami, Yuta,Ogihara, Hitoshi,Nagamatsu, Shinichi,Asakura, Kiyotaka,Yamanaka, Ichiro
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- Method for hydrocarbylation synthesis of trisubstituted and tetrasubstituted olefins from non-terminal olefins
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The invention discloses a method for hydrocarbylation synthesis of trisubstituted and tetrasubstituted olefins from non-terminal olefins, wherein the method comprises the steps: carrying out hydrocarbylation reaction on the non-terminal olefins and sulfoxide in the presence of ferric salt and hydrogen peroxide, carrying out one-pot reaction on disubstituted non-terminal olefins to generate the trisubstituted olefins, and carrying out one-pot reaction on the trisubstituted non-terminal olefins to generate the tetrasubstituted olefins. In the method, sulfoxide is simultaneously used as a hydrocarbylation reagent and a solvent of olefins, and one more hydrocarbyl substituent is added to a reaction product compared with a double-bond carbon atom of a reactant, so that an olefin carbon chain isincreased; the reaction conditions are mild, the selectivity is good, the yield is high, and industrial production is facilitated.
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Paragraph 0054-0066
(2021/02/06)
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- Hydrodeoxygenation of m-cresol as a depolymerized lignin probe molecule: Synergistic effect of NiCo supported alloys
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Three bimetallic Ni-Co (Ni:Co ratio 1:3, 1:1 and 3:1) and two monometallic (Ni and Co) nanoparticles supported on Al2O3 were synthesized by incipient wet impregnation and characterized by various technics (N2-physisorption, XRD, H2-TPR, CO-chemisorption and elemental analysis). It was demonstrated by XRD that NiCo alloys nanoparticles were present on bimetallic solids. The catalytic properties of all catalysts were determined for the hydrodeoxygenation of m-cresol at 340 °C under 4 MPa of total pressure. It was demonstrated that NiCo alloy developed better deoxygenation catalytic properties than pure Ni metallic phase, these properties being evaluated both by the total reaction rate (kTOT) and the selectivity into deoxygenation products. Indeed, bimetallic NiCo(3:1)/Al2O3 was 1.2 times more active than Ni/Al2O3 and 8.8 times than Co/Al2O3, deoxygenated products being favored on bimetallic catalysts compared to Ni one. In addition, the kTOT values seems to be related to the amount of CO uptakes, indicating that active sites in HDO were of similar nature than those allowing the adsorption of CO, and could be oxygen vacancies which were promoted in bimetallic Ni-Co particles.
- Gon?alves, Vinicius Ottonio O.,Talon, Walter Henrique S.M.,Kartnaller, Vinicius,Venancio, Fabricio,Cajaiba, Jo?o,Cabioc'h, Thierry,Clacens, Jean-Marc,Richard, Frédéric
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p. 135 - 144
(2021/01/04)
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- Effects of Water Addition on the Conversion of o-Cresol in the Presence of In Situ Ni–Mo Sulfide Catalysts
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Abstract: Ni-Mo sulfide systems generated in situ from precursor salts were used for the hydrodeoxygenation of o-cresol. After the reaction, the catalysts were recovered and analyzed by transmission electron microscopy and X-ray photoelectron spectroscopy. It was shown that the addition of water into the reaction system affects the composition of the o-cresol conversion product due to a change in the texture and phase composition of the surface layer of the in situ sulfide particles.
- Kniazeva,Kuchinskaya,Erasheva
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p. 682 - 687
(2021/04/09)
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- Influence of Intracrystalline Ionic Strength in MFI Zeolites on Aqueous Phase Dehydration of Methylcyclohexanols
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The impact of the concentration of hydrated hydronium ions and in turn of the local ionic strength in MFI zeolites has been investigated for the aqueous phase dehydration of 4-methylcyclohexanol (E1 mechanism) and cis-2-methylcyclohexanol (E2 mechanism). The E2 pathway with the latter alcohol led to a 2.5-fold higher activity. The catalytic activity normalized to the hydronium ions (turnover frequency, TOF) passed through a pronounced maximum, which is attributed to the increasing excess chemical potential of the alcohols in the pores, increasing in parallel with the ionic strength and the additional work caused by repulsive interactions and charge separation induced by the bulky alcohols. While the maximum in rate observed is invariant with the mechanism or substitution, the reaction pathway is influencing the activation parameters differently.
- Milakovi?, Lara,Hintermeier, Peter H.,Liu, Yue,Baráth, Eszter,Lercher, Johannes A.
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supporting information
p. 24806 - 24810
(2021/09/08)
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- ISOMERIZATION OF ALKENES
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The present invention relates to an isomerization method for alkenes, comprising of reaction an alkene with a Ni(I)-compound. By this method, E-Alkenes are obtained in excellent yield.
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Page/Page column 20-21; 23-24
(2020/04/25)
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- Nickel-catalyzed deoxygenation of oxiranes: Conversion of epoxides to alkenes
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Deoxygenation of epoxides takes place under the catalysis of nickel in the presence of diethylzinc as a deoxygenation agent to yield alkenes. Epoxides with a wide variety of substitution patterns are deoxygenated in this catalytic system to give terminal, 1,1-disubstituted, 1,2-disubstituted, trisubstituted, and tetrasubstituted alkenes in high yields. Reactions of 1,2-disubstituted epoxides we examined proceeded in an E-stereoselective manner. High compatibility with other functional groups through this transformation was also observed.
- Mori, Takamichi,Takeuchi, Yoshihito,Hojo, Makoto
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supporting information
(2020/01/24)
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- Radical dehydroxylative alkylation of tertiary alcohols by Ti catalysis
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Deoxygenative radical C?C bond-forming reactions of alcohols are a long-standing challenge in synthetic chemistry, and the current methods rely on multistep procedures. Herein, we report a direct dehydroxylative radical alkylation reaction of tertiary alcohols. This new protocol shows the feasibility of generating tertiary carbon radicals from alcohols and offers an approach for the facile and precise construction of all-carbon quaternary centers. The reaction proceeds with a broad substrate scope of alcohols and activated alkenes. It can tolerate a wide range of electrophilic coupling partners, including allylic carboxylates, aryl and vinyl electrophiles, and primary alkyl chlorides/bromides, making the method complementary to the cross-coupling procedures. The method is highly selective for the alkylation of tertiary alcohols, leaving secondary/primary alcohols (benzyl alcohols included) and phenols intact. The synthetic utility of the method is highlighted by its 10-g-scale reaction and the late-stage modification of complex molecules. A combination of experiments and density functional theory calculations establishes a plausible mechanism implicating a tertiary carbon radical generated via Ti-catalyzed homolysis of the C?OH bond.
- Xie, Hao,Guo, Jiandong,Wang, Yu-Quan,Wang, Ke,Guo, Peng,Su, Pei-Feng,Wang, Xiaotai,Shu, Xing-Zhong
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supporting information
p. 16787 - 16794
(2020/11/09)
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- E-Olefins through intramolecular radical relocation
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Full control over the selectivity of carbon-carbon double-bond migrations would enable access to stereochemically defined olefins that are central to the pharmaceutical, food, fragrance, materials, and petrochemical arenas. The vast majority of double-bond migrations investigated over the past 60 years capitalize on precious-metal hydrides that are frequently associated with reversible equilibria, hydrogen scrambling, incomplete E/Z stereoselection, and/or high cost. Here, we report a fundamentally different, radical-based approach.We showcase a nonprecious, reductant-free, and atom-economical nickel (Ni)(I)-catalyzed intramolecular 1,3-hydrogen atom relocation to yield E-olefins within 3 hours at room temperature. Remote installations of E-olefins over extended distances are also demonstrated.
- Kapat, Ajoy,Sperger, Theresa,Guven, Sinem,Schoenebeck, Franziska
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p. 391 - 396
(2019/02/03)
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- Controllable Isomerization of Alkenes by Dual Visible-Light-Cobalt Catalysis
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We report herein that thermodynamic and kinetic isomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction further. Transformation of exocyclic alkenes into the corresponding endocyclic products could be efficiently realized by using 4CzIPN and Co(acac)2 in the absence of any additional ligands. Spectroscopic and spectroelectrochemical investigations indicate CoI being involved in the generation of a Co hydride, which subsequently adds to alkenes initiating the isomerization.
- Meng, Qing-Yuan,Schirmer, Tobias E.,Katou, Kousuke,K?nig, Burkhard
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supporting information
p. 5723 - 5728
(2019/04/03)
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- Trans -2 - substituted cycloalkyl three fluoro potassium borate synthesis method (by machine translation)
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The invention discloses trans - 2 - substituted cyclohexyl three fluoro potassium borate synthesis method, which belongs to the field of organic synthesis. From the cyclic ketone starting curing and reagent or lithium reagent addition subsequently dehydrated and gets substituted alkenes, subsequently with the catechol borane or after aminol borane addition reaction, fluorine hydride potassium direct quenching treatment to obtain trans - 2 - substituted cyclohexyl three fluoro potassium borate, the catechol borane to obtain the racemate product, [...] photoinitiators enantiomerically pure product. The method has low cost, convenient source of raw materials, the operation is simple, and has industrial amplifying of the prospect. (by machine translation)
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Paragraph 0020
(2019/04/04)
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- One-Pot Synthesis of N-Substituted Alkylaminocyclohexanols by the Addition of Electrophiles Formed in situ in the System Н2О2 + HBr (HCl)
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Highly selective one-pot synthesis of N-substituted aminocyclohexanols has been performed by hydroxyhalogenation of the corresponding cyclohexenes with electrophilic reagents formed in situ in the system Н2О2 + HHlg (Hlg = Cl, Br), with subsequent substitution of halogen atoms with amines. Some products were tested as antimicrobial additives to motor oils and cooling lubricants and showed high antibacterial and antifungal activity.
- Sadygov,Alimardanov, Kh. M.,Ismailova, Sh. I.,Babaev
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p. 650 - 657
(2018/06/14)
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- Effect of ketene additive and Si/Al ratio on the reaction of methanol over HZSM-5 catalysts
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The influence of ketene as possible intermediate for the reaction of methanol to aromatics was investigated over HZSM-5 catalysts (Si/Al ratio of 15 and 9) using diketene-acetone (2,2,6-trimethyl-4H-1,3-dioxin-4-one) as ketene precursor under atmospheric
- Hassanpour, Javad,Zamani, Mehdi,Dabbagh, Hossein A.
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- Selective Production of Renewable para-Xylene by Tungsten Carbide Catalyzed Atom-Economic Cascade Reactions
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Tungsten carbide was employed as the catalyst in an atom-economic and renewable synthesis of para-xylene with excellent selectivity and yield from 4-methyl-3-cyclohexene-1-carbonylaldehyde (4-MCHCA). This intermediate is the product of the Diels–Alder reaction between the two readily available bio-based building blocks acrolein and isoprene. Our results suggest that 4-MCHCA undergoes a novel dehydroaromatization–hydrodeoxygenation cascade process by intramolecular hydrogen transfer that does not involve an external hydrogen source, and that the hydrodeoxygenation occurs through the direct dissociation of the C=O bond on the W2C surface. Notably, this process is readily applicable to the synthesis of various (multi)methylated arenes from bio-based building blocks, thus potentially providing a petroleum-independent solution to valuable aromatic compounds.
- Dai, Tao,Li, Changzhi,Li, Lin,Zhao, Zongbao Kent,Zhang, Bo,Cong, Yu,Wang, Aiqin
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supporting information
p. 1808 - 1812
(2018/02/10)
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- Probing Synergistic Effects of DNA Methylation and 2′-β-Fluorination on i-Motif Stability
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The possible role of DNA i-motif structures in telomere biology and in the transcriptional regulation of oncogene promoter regions is supported by several recent studies. Herein we investigate the effect of four cytidine nucleosides (and combinations thereof) on i-motif structure and stability, namely 2′-deoxycytidine (dC), 2′-deoxy-5-methyl-cytidine (5-Me-dC), 2′-deoxy-2′-fluoro-arabinocytidine (2′F-araC), and 2′-deoxy-2′-fluoro-5-methyl-arabinocytidine (5-Me-2′F-araC). The base pair 5-Me-2′F-araC:2′F-araC produced i-motifs with a pH1/2 (“pKa”) value that closely matches physiological pH (7.34±0.3). NMR analysis of the most stable telomeric sequence (HJ-2) at pH 7.0 indicated that the structure is stabilized by hybrid 5-Me-dC:2′F-araC hemiprotonated base pairs and therefore highlights the significance of the interplay between base and sugar modifications on the stability of i-motif structures.
- Abou Assi, Hala,Lin, Yu Chen,Serrano, Israel,González, Carlos,Damha, Masad J.
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supporting information
p. 471 - 477
(2017/12/15)
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- Alkene Isomerization by “Sandwich” Diimine-Palladium Catalysts
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In contrast to traditional diimine-palladium complexes, sterically hindered “sandwich” diimine-palladium adducts act as olefin isomerization catalysts. Terminal olefins are selectively converted to 2-olefins by a sequence of migratory insertion, β-hydride elimination, and olefin displacement. The reaction is performed at 0 °C with 1 mol % of an air-stable precatalyst and tolerates functional groups such as ketones, silyl ethers, and halogens. The isomerization may be used to produce silyl enol ethers from protected allylic alcohols.
- Kocen, Andrew L.,Klimovica, Kristine,Brookhart, Maurice,Daugulis, Olafs
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supporting information
p. 787 - 790
(2017/04/21)
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- Toward a mild dehydroformylation using base-metal catalysis
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Dehydroformylation, or the reaction of aldehydes to produce alkenes, hydrogen gas, and carbon monoxide, is a powerful transformation that is underdeveloped despite the high industrial importance of the reverse reaction, hydroformylation. Interestingly, nature routinely performs a related transformation, oxidative dehydroformylation, in the biosynthesis of cholesterol and related sterols under mild conditions using base-metal catalysts. In contrast, chemists have recently developed a non-oxidative dehydroformylation method; however, it requires high temperatures and a precious-metal catalyst. Careful study of both approaches has informed our efforts to design a base-metal catalyzed, mild dehydroformylation method that incorporates benefits from each while avoiding several of their respective disadvantages. Importantly, we show that cooperative base metal catalysis presents a powerful, mechanistically unique approach to reactions which are difficult to achieve using conventional catalyst design.
- Abrams, Dylan J.,West, Julian G.,Sorensen, Erik J.
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p. 1954 - 1959
(2017/03/09)
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- One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: Insights into the major reaction pathways
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For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C6-C8 olefins over the catalysts' Br?nsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C6-C8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Br?nsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.
- Xing, Shiyou,Lv, Pengmei,Wang, Jiayan,Fu, Junying,Fan, Pei,Yang, Lingmei,Yang, Gaixiu,Yuan, Zhenhong,Chen, Yong
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p. 2961 - 2973
(2017/02/05)
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- Well-defined dendrimer encapsulated ruthenium SCILL catalysts for partial hydrogenation of toluene in liquid-phase
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Dendrimer encapsulated ruthenium nanoparticles (RuDEN) were prepared and immobilized on silica 60 and silica 100. The size of the supported RuDENs was investigated using HRTEM and the generation six G6-RuDEN was found to be the most stable RuDEN upon immobilization. The catalysts were evaluated in the liquid-phase hydrogenation of toluene at a hydrogen pressure of 30 bar and 110 °C. Several ionic liquids were used as coatings for the G5-RuSil100 catalysts to give various Solid Catalysts with Ionic Liquid Layer (SCILL). In each case the selectivity towards methylcyclohexenes was increased compared to the uncoated catalyst, accompanied by an expected decrease in activity with the highest methylcyclohexene selectivity being observed when using [EMIM][NTf2] as a coating.
- Antonels, Nathan Charles,Benjamin Williams, Marc,Meijboom, Reinout,Haumann, Marco
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p. 156 - 160
(2016/07/06)
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- Direct conversion of carboxylic acids (Cn) to alkenes (C2n - 1) over titanium oxide in absence of noble metals
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Carbon-carbon bond formations and deoxygenation reactions are important for biomass up-grading. The classical ketonic decarboxylation of carboxylic acids provides symmetrical ketones with 2n + 1 carbon atoms and eliminates three oxygen atoms. Herein, this reaction is carried out with titanium oxide at 400°C, and an olefin with 2n + 1 carbon atoms is obtained instead of the ketone. For olefin formation hydrogen transfer reactions are required from suitable precursors to form aromatics and coke. Additional aldol condensation reactions increase further molecular weight in the product mixture. Hence, a combination of titanium oxide with a hydrodeoxygenation bed provides double amount of diesel fuel as the combination with zirconium oxide when reacting hexose-derived pentanoic acid.
- Oliver-Tomas, Borja,Renz, Michael,Corma, Avelino
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- METHOD FOR PRODUCING ORGANIC COMPOUND
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PROBLEM TO BE SOLVED: To provide a method of subjecting a compound having on one carbon atom a carbon atom constituting a carbon-carbon double bond and a functional group such as a hydroxyl group to a reductive reaction condition and producing an organic compound having the functional group substituted with a hydrogen atom. SOLUTION: There is provided a method for producing a compound represented by a formula (50) from a raw material compound represented by a formula (10). The method includes a step of irradiating a reaction system with light, the reaction system comprising the raw material compound, a hydrogen source compound, and a catalyst having a palladium component supported by a carrier containing titanium oxide. (R11 to R15 are a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms which may have a cyclic structure or a derivative group thereof, or a heteroatom-containing group having 1 to 20 carbon atoms which may have a cyclic structure or a derivative group thereof; and R16 is a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms or an acyl group having 1 to 20 carbon atoms which may have a cyclic structure, or -CH(CH2OH)2).) COPYRIGHT: (C)2015,JPO&INPIT
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Paragraph 0084-0087; 0097; 0129; 0136; 0138
(2018/10/16)
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- Hydrodesulfurization of dibenzothiophene, 4,6-dimethyldibenzothiophene, and their hydrogenated intermediates over bulk tungsten phosphide
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The kinetics of the hydrodesulfurization (HDS) of dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (4,6-DMDBT), and their hydrogenated intermediates over bulk tungsten phosphide (WP) was studied. WP possessed high hydrogenation/dehydrogenation activity but was highly sensitive to piperidine inhibition. 4,6-DMDBT reacted faster than DBT, and both DBT and 4,6-DMDBT reacted mainly through the hydrogenation pathway. The methyl groups suppressed the direct desulfurization of 4,6-DMDBT but significantly promoted the hydrogenation of 4,6-DMDBT and the dehydrogenation of 1,2,3,4-tetrahydro-4,6-dimethyldibenzothiophene (TH-4,6-DMDBT) and 1,2,3,4,4a,9b-hexahydro-4,6-dimethyldibenzothiophene, but decreased the rate of hydrogenation of TH-4,6-DMDBT. Piperidine inhibited the HDS of 4,6-DMDBT much more strongly than that of DBT. Substantial dehydrogenation of TH-4,6-DMDBT to 4,6-DMDBT and two of its isomers occurred. The formation of these 4,6-DMDBT isomers in the dehydrogenation of TH-4,6-DMDBT and the hydrocracking of 1-methyl-4-(3-methylcyclohexyl)-benzene, as well as the formation of cyclopentylphenylmethane and (cyclopentylmethyl)cyclohexane, is ascribed to the metallic character of WP.
- Yang, Lei,Li, Xiang,Wang, Anjie,Prins, Roel,Chen, Yongying,Duan, Xinping
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p. 330 - 343
(2015/09/01)
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- Supported imidazolylphosphine catalysts for highly (E)-selective alkene isomerization
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For fine chemical synthesis, immobilized catalysts offer little advantage if they produce a product mixture that must be separated. Selective isomerization of terminal olefins is achieved by heterogenized bifunctional catalysts. Outstanding and consistent (E)-selectivity (>99%) even in cases where (E) and (Z) isomers are of comparable stability, combined with modest catalyst loadings (1 to 2 mol %), set these catalysts apart from previously reported systems. Ease of catalyst removal and high geometric selectivity avoid tedious purifications.
- Erdogan, Gulin,Grotjahn, Douglas B.
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supporting information
p. 2818 - 2821
(2014/06/23)
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- Increasing the aromatic selectivity of quinoline hydrogenolysis using Pd/MOx-Al2O3
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Catalysts consisting of Pd nanoparticles supported on highly dispersed TiOx-Al2O3, TaOx-Al2O3, and MoOx-Al2O3 are studied for catalytic quinoline hydrogenation and selective C-N bond cleavage at 275°C and 20 bar H2. The Pd/MOx-Al2O3 materials exhibit significantly greater aromatic product selectivity and thus 10-15 % less required H2 for a given level of denitrogenation relative to an unmodified Pd/Al2O3 catalyst.
- Bachrach, Mark,Morlanes-Sanchez, Natalia,Canlas, Christian P.,Miller, Jeffrey T.,Marks, Tobin J.,Notestein, Justin M.
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p. 1832 - 1838
(2015/02/19)
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- Towards a practical development of light-driven acceptorless alkane dehydrogenation
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The efficient catalytic dehydrogenation of alkanes to olefins is one of the most investigated reactions in organic synthesis. In the coming years, an increased supply of shorter-chain alkanes from natural and shale gas will offer new opportunities for inexpensive carbon feedstock through such dehydrogenation processes. Existing methods for alkane dehydrogenation using heterogeneous catalysts require harsh reaction conditions and have a lack of selectivity, whereas homogeneous catalysis methods result in significant waste generation. A strong need exists for atom-efficient alkane dehydrogenations on a useful scale. Herein, we have developed improved acceptorless catalytic systems under optimal light transmittance conditions using trans-[Rh(PMe3) 2(CO)Cl] as the catalyst with different additives. Unprecedented catalyst turnover numbers are obtained for the dehydrogenation of cyclic and linear (from C4) alkanes and liquid organic hydrogen carriers. These reactions proceed with unique conversion, thereby providing a basis for practical alkane dehydrogenations.
- Chowdhury, Abhishek Dutta,Weding, Nico,Julis, Jennifer,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 6477 - 6481
(2014/06/24)
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- Salt-free preparation of trimethylsilyl ethers by B(C6F 5)3-catalyzed transfer silylation by using a Me 3SiH surrogate
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An unprecedented transfer silylation of alcohols catalyzed by the strong Lewis acid B(C6F5)3 is described. Gaseous Me3SiH is released in situ by B(C6F5) 3-catalyzed decomposition of 3-trimethylsilylcyclohexa-1,4-diene and subsequently reacts with an alcohol in a dehydrogenative Si-O coupling promoted by the same boron catalyst. Benzene and dihydrogen are formed during the reaction, but no salt waste is. This expedient protocol is applicable to several silicon groups, and the preparation of trimethylsilyl ethers presented here is potentially useful for alcohol derivatization prior to GLC analysis. Copyright
- Simonneau, Antoine,Friebel, Jonas,Oestreich, Martin
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supporting information
p. 2077 - 2083
(2014/04/17)
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- Late-stage deoxyfluorination of alcohols with phenofluor
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An operationally simple protocol for the selective deoxyfluorination of structurally complex alcohols is presented. Several fluorinated derivatives of natural products and pharmaceuticals have been prepared to showcase the potential of the method for late-stage diversification and its functional group compatibility. A series of simple guidelines for predicting the selectivity in substrates with multiple alcohols is given.
- Sladojevich, Filippo,Arlow, Sophie I.,Tang, Pingping,Ritter, Tobias
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supporting information
p. 2470 - 2473
(2013/03/28)
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- Stereoselective alkene isomerization over one position
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Although controlling both the position of the double bond and E:Z selectivity in alkene isomerization is difficult, 1 is a very efficient catalyst for selective mono-isomerization of a variety of multifunctional alkenes to afford >99.5% E-products. Many reactions are complete within 10 min at room temperature. Even sensitive enols and enamides susceptible to further reaction can be generated. Catalyst loadings in the 0.01-0.1 mol% range can be employed. E-to-Z isomerization of the product from diallyl ether was only -6 times as fast as its formation, showing the extremely high kinetic selectivity of 1.
- Larsen, Casey R.,Grotjahn, Douglas B.
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supporting information; experimental part
p. 10357 - 10360
(2012/08/08)
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- Organic reactivity of alcohols in superheated aqueous salt solutions: An overview
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The low dielectric constant and high self-dissociation constant of water in a temperature range between 150 and 250 °C make it a very appealing solvent for synthesis. Surprisingly, while organic chemistry in water at low temperature or around its critical point has been investigated in detail, very little seems to be known about the behaviour of organic molecules under hydrothermal conditions. The present work thus aims at shading some light on this field. As a start, we decided to investigate the reactions in which alcohols can undergo in water in the above-mentioned temperature range. Knowing that very strong salt effects on organic reactions have already been observed in super critical water, the impact of salt on the outcome of our tests was also investigated in detail.
- Avola, Sabine,Goettmann, Frederic,Antonietti, Markus,Kunz, Werner
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scheme or table
p. 1568 - 1573
(2012/10/07)
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- Restricted rotation due to the lack of free space within a capsule translates into product selectivity: Photochemistry of cyclohexyl phenyl ketones within a water-soluble organic capsule
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The rotational mobility of organic guest molecules when included within a confined capsule is restricted and this feature could be translated into product selectivity as established with the photochemical behavior of cyclohexyl phenyl ketones. The Royal Society of Chemistry.
- Kulasekharan, Revathy,Choudhury, Rajib,Prabhakar, Rajeev,Ramamurthy
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body text
p. 2841 - 2843
(2011/05/05)
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- Hydrodeoxygenation of bio-derived phenols to hydrocarbons using RANEY Ni and Nafion/SiO2 catalysts
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A simple, green, cost- and energy-efficient route for converting phenolic components in bio-oil to hydrocarbons and methanol has been developed, with nearly 100% yields. In the heterogeneous catalysts, RANEY Ni acts as the hydrogenation catalyst and Nafion/SiO2 acts as the Bronsted solid acid for hydrolysis and dehydration.
- Zhao, Chen,Kou, Yuan,Lemonidou, Angeliki A.,Li, Xuebing,Lercher, Johannes A.
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experimental part
p. 412 - 414
(2010/04/04)
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- Palladium(0)-mediated rapid methylation and fluoromethylation on carbon frameworks by reacting methyl and fluoromethyl iodide with aryl and alkenyl boronic acid esters: Useful for the synthesis of [11C]CH 3-C-and [18F]FCH2-C-containing PET tracers (PET = positron emission tomography)
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The rapid methylation and fluoromethylation on aryl and alkenyl carbon frameworks by reacting methyl and fluoromethyl iodide with aryl and alkenyl boronates have been studied with the focus on the realization of the synthesis of [11C]CH3- and [18F]FCH2-labeled positron emission tomography (PET) tracers. The coupling of methyl iodide and pinacol phenylboronate (40 equiv) is accomplished in > 91% yield within 5 min at 60 °C under the conditions of [Pd2(dba)3]/P(o- CH3C6H4)3/K2CO 3 (0.5:2:2; dba = di-benzylideneacetone) in DMF. The reaction shows a high generality and is applicable to various types of aryl and alkenyl boronates, giving the corresponding methylated derivatives in high yields (80-99). This reaction is also useful for the rapid incorporation of the fluoromethyl group. Thus, this boron protocol provides a firm chemical basis for the synthesis of 11C- and 18F-incorporated PET tracers and can be used as a complementary method for [11C]methylation together with our previous and ongoing processes using organotributylstannanes.
- Doi, Hisashi,Ban, Ikuya,Nonoyama, Akihito,Sumi, Kengo,Kuang, Chunxiang,Hosoya, Takamitsu,Tsukada, Hideo,Suzuki, Masaaki
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experimental part
p. 4165 - 4171
(2009/12/01)
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- METHOD OF RAPID METHYLATION, KIT FOR PREPARING PET TRACER AND METHOD OF PRODUCING PET TRACER
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It is intended to provide a method of rapid methylation of an aromatic compound or an alkenyl compound, which is capable of obtaining an aromatic compound or an alkenyl compound labeled with a methyl group or a fluoromethyl group under a mild condition rapidly in high yield using an organic boron compound whose toxicity is not so high as a substrate; a kit for preparing a PET tracer to be used in the same, and a method of producing a PET tracer using the same. In an aprotic polar solvent, methyl iodide or X-CH2F (wherein X is a functional group which can be easily released as an anion), an organic boron compound in which an aromatic ring or an alkenyl group is attached to boron are subjected to cross-coupling in the presence of a palladium(0) complex, a phosphine ligand, and a base.
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Page/Page column 10
(2009/07/10)
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- METHOD OF RAPID METHYLATION OF ALKENE COMPOUND AND KIT FOR PET TRACER PREPARATION USING THE SAME
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To provide a method of rapid methylation of alkenes, which is applicable to the preparation of a PET tracer and which enables alkenes to be methylated through cross coupling between SP2 (alkenyl) and SP3 (alkyl) carbon atoms rapidly and in a high yield. Methyl iodide and an alkenyltrialkylstannane are subjected to cross coupling in an aprotic polar solvent in the presence of a palladium complex having a valence of 0, a phosphine ligand, a cuprous halide, and a carbonate and/or alkali metal fluoride.
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Page/Page column 5; 6; 13
(2008/12/07)
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- Unsaturated aldehydes as alkene equivalents in the Diels-Alder reaction
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A one-pot procedure is described for using α,β-unsaturated aldehydes as olefin equivalents in the Diels-Alder reaction. The method combines the normal electron demand cycloaddition with aldehyde dienophiles and the rhodium-catalyzed decarbonylation of aldehydes to afford cyclohexenes with no electron-with-drawing substituents. In this way, the aldehyde group serves as a traceless control element to direct the cycloaddition reaction. The Diels-Alder reactions are performed in a diglyme solution in the presence of a catalytic amount of boron trifluoride etherate. Subsequent quenching of the Lewis acid, addition of 0.3% of [Rh(dppp)2Cl] and heating to reflux achieves the ensuing decarbonylation to afford the product cyclohexenes. Under these conditions, acrolein, crotonaldehyde and cinnamaldehyde have been reacted with a variety of 1,3-dienes to afford cyclohexenes in overall yields between 53 and 88%. In these transformations, the three aldehydes serve as equivalents of ethylene, propylene and styrene, respectively.
- Taarning, Esben,Madsen, Robert
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supporting information; experimental part
p. 5638 - 5644
(2009/05/30)
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- Ionic-liquid-like copolymer stabilized nanocatalysts in ionic liquids: II. Rhodium-catalyzed hydrogenation of arenes
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Rhodium nanoparticles stabilized by the ionic-liquid-like copolymer poly[(N-vinyl-2-pyrrolidone)-co-(1-vinyl-3-butylimidazolium chloride)] were used to catalyze the hydrogenation of benzene and other arenes in ILs. The nanoparticle catalysts can endure forcing conditions (75 °C, 40 bar H2), resulting in high reaction rates and high conversions compared with other nanoparticles that operate in ILs. The hydrogenation of benzene attained record total turnovers of 20,000, and the products were easily separated without being contaminated by the catalysts. Other substrates, including alkyl-substituted arenes, phenol, 4-n-propylphenol, 4-methoxylphenol, and phenyl-methanol, were studied and in most cases were found to afford partially hydrogenated products in addition to cyclohexanes. In-depth investigations on reaction optimization, including characterization of copolymers, transmission electron microscopy, and an infrared spectroscopic study of nanocatalysts, were also undertaken.
- Zhao, Chen,Wang, Han-zhi,Yan, Ning,Xiao, Chao-xian,Mu, Xin-dong,Dyson, Paul J.,Kou, Yuan
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- Silica-supported dendrimer-palladium complex-catalyzed selective hydrogenation of dienes to monoolefins
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The selective hydrogenation of cyclic and acyclic dienes to monoolefins occurs under very mild conditions, in the presence of silica-supported PAMAM-Pd complexes. The activity and selectivity of this reaction is sensitive to the dendrimer structure. These dendritic complexes display excellent recycle properties, retaining activity for up to eight recycles.
- Zweni, Pumza P.,Alper, Howard
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p. 725 - 731
(2007/10/03)
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- Transformations of β-alkylcyclohexane hydrocarbons on modified pentasils with participation of methanol and oxidants
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The reactions of dehydroalkylation of methylcyclohexane, ethylcyclohexane, and methylcyclohexene isomers and toluene alkylation with methanol on platinum-and gallium-modified pentasil in the presence of an O 2-CO2 mixture was studied. Optimum conditions were found for the one-step dehydroalkylation of methylcyclohexane on the ring. Under these conditions, the degree of conversion of methylcyclohexane and methylcyclohexene isomers into xylene isomers is above that of toluene alkylation to afford xylene. According to the discussed reaction mechanism, the dehydroalkylation of cyclohexane hydrocarbons on Pt, Ga-pentasil involves both the steps of formation of unsaturated intermediates and toluene in status nascendi. Nauka/Interperiodica 2006.
- Alimardanov,Velieva,Dadasheva,Rustamov
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p. 353 - 361
(2008/04/18)
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- Rapid methylation on carbon frameworks useful for the synthesis of 11CH3-incorporated PET tracers: Pd(0)-mediated rapid coupling of methyl iodide with an alkenyltributylstannane leading to a 1-methylalkene
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The Pd(0)-mediated rapid coupling of methyl iodide with an excess of alkenyltributylstannane was examined with the aim of incorporating a short-lived 11C-labeled methyl group into a biologically significant organic compound with a 1-methylalkene unit for the synthesis of a PET tracer. Four sets of reaction conditions (A-D) were used, all performed in DMF at 60 °C for 5 min. Condition B, using CH3I/stannane/Pd2(dba) 3/P(o-tolyl)3/CuCl/K2CO3 (1: 40: 0.5: 4-6: 2: 5), works well in almost all cases. Condition D, using CH 3I/stannane/Pd2(dba)3/P(o-tolyl) 3/CuX (X = Br, Cl, or I)/CsF (1: 40: 0.5-5: 2-20: 2-20: 5-50), shows the best results with regard to general applicability to tin substrates, affording the corresponding methylated product in >90% yield based on consumption of methyl iodide. P(t-Bu)2Me was less effective than P(o-tolyl)3, particularly for α,β-unsaturated carbonyl substrates. No regio- or stereoisomerization occurred under these reaction conditions. The efficiency of the protocol was demonstrated by synthesis of an 11C-methylated compound. The Royal Society of Chemistry 2006.
- Hosoya, Takamitsu,Sumi, Kengo,Doi, Hisashi,Wakao, Masahiro,Suzuki, Masaaki
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p. 410 - 415
(2007/10/03)
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- User-friendly methylation of aryl and vinyl halides and pseudohalides with DABAL-Me3
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An extremely technically simple cross-methylation of aryl and vinyl halides and pseudohalides using an air-stable adduct of trimethylaluminium with a Pd(0) catalyst supported by commercially available biarylphosphines gives excellent yields of methylated products (mainly > 95%). Reactions can be run with either 0.5 mol% catalyst or without requiring the exclusion of atmospheric oxygen or the drying of solvents in some cases. A wide variety of functional groups is tolerated including CN, OH, CO2R, CHO and NO2.
- Cooper, Thea,Novak, Andrew,Humphreys, Luke D.,Walker, Matthew D.,Woodward, Simon
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p. 686 - 690
(2007/10/03)
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- Kinetics and mechanism of unimolecular heterolysis of framework compounds: XVII. Solvation effects in dehydrobromination of tert-butyl bromide, 1-bromo-1-methylcyclohexane, and 2-bromo-2-methyladamantane in dipolar aprotic solvents
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Dehydrobromination rate of tert-butyl bromide, 1-bromo-1-methylcyclohexane, and 2-bromo-2-methyladamantane grows with increasing polarity and dipole moment of solvents. No correlation was found between rate constants of the process and electrophilicity or ionizing power of the solvents. The observed solvation effects are due mainly to dispersion interactions. 2005 Pleiades Publishing, Inc.
- Vasil'kevich,Ponomareva,Dvorko
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p. 1594 - 1597
(2007/10/03)
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- Synthesis of biologically active substances based on phenoxyethanol derivatives
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By reaction of phenoxyethanol with diverse structure acyl chlorides phenoxyethanol esters were synthesized containing in the molecule fragments of undecene acid and also of some ketocarboxylic acids. The latter acids were obtained by ozonation of alkylcyclenes. 2005 Pleiades Publishing, Inc.
- Kukovinets,Yamansarova,Kasradze,Lozhkina,Zainullin,Abdullin
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p. 673 - 677
(2007/10/03)
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- Dehydroalkylation of methylcyclohexane by methanol on modified zeolites: Kinetic features and reaction mechanism
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The reaction of methylcyclohexane dehydroalkylation by methanol on modified forms of mordenite and pentasil was studied. The kinetic features of the process in the presence of HNa-pentasil modified by gallium and iron oxides and phosphorus were investigated. A kinetic model that fairly well describes the process at 430-570°C is suggested. The reaction mechanism is considered, which involves the dehydroalkylation of methylcyclohexane by methanol via the intermediate dehydrogenation of both hydrocarbons and alcohol and the subsequent interaction of the unsaturated compounds formed with formaldehyde adsorbed on the catalyst surface. Copyright
- Alimardanov,Velieva,Suleimanova,Tairova,Sh Sadygova
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- Polysulfones: Catalysts for alkene isomerization
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A radical intermediate is generated when methylidenecyclopentane (1) is isomerized by SO2 into 1-methylcyclopentene (3) through the formation of a polysulfone polymer (PS), which first abstracts a hydrogen atom from the alkene. The allyl radical intermediate 2 abstracts a hydrogen atom from another alkene molecule 1, to yield the isomerized alkene and regenerating the allyl radical. Polysulfones are organic catalysts.
- Markovic, Dean,Vogel, Pierre
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p. 2928 - 2930
(2007/10/03)
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- Kinetics and Mechanism of Monomolecular Heterolysis of Commercial Organohalogen Compounds: XXXIV. Solvent Effect on the Heterolysis Rate of 1-Chloro-1-methylcyclohexane. Correlation Analysis of Solvation Effects in Heterolysis of 1-Chloro-1-methylcyclohexane and 1-Chloro-1-methylcyclopentane
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The kinetics of heterolysis of 1-chloro-1-methylcyclohexane in 9 protic and 25 aprotic solvents at 25°C were studied by the verdazyl method. The kinetic equation is v = k[RCl] (El mechanism). The heterolysis rate of 1-chloro-1-methylcyclohexane in protic solvents is two orders of magnitude lower than that of 1-chloro-1-methylcyclopentane, whereas in low-polarity and nonpolar aprotic solvents the rates are close. A correlation analysis was made to reveal the solvation effects in heterolysis of both chlorides in a set of 9 protic and 25 aprotic solvents, and separately in protic and aprotic solvents.
- Dvorko,Koshchii,Ponomareva
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p. 204 - 212
(2007/10/03)
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