- Heterogenized C-Scorpionate Iron(II) Complex on Nanostructured Carbon Materials as Recyclable Catalysts for Microwave-Assisted Oxidation Reactions
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The C-scorpionate iron(II) complex [FeCl2(Tpm)] [Tpm=κ3-HC(C3H3N2)3] (1) was immobilized on five different nanostructured carbon materials (nanodiamonds, graphene nanoplatelets, graphene ox
- Ribeiro, Ana P. C.,Martins, Luísa M. D. R. S.,Carabineiro, Sónia A. C.,Buijnsters, Josephus G.,Figueiredo, José L.,Pombeiro, Armando J. L.
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- Preparation of supported catalyst and 1, 4 - cyclohexanediol prepared by hydrogenation of fixed bed hydroquinone
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The invention relates γ-Al. 2 O3 Or γ-Al. 2 O3 The preparation of and inorganic carbon supported catalysts and the catalytic hydrogenation of 1, 4 - cyclohexanediol in fixed beds mainly uses γ-Al. 2 O3 Or γ-Al. 2 O3 The transition metal supported by the inorganic carbon is a catalyst, at H. 2 The reaction was carried out in a solution filled with hydroquinone, and 1, 4 - cyclohexanediol was prepared on a fixed bed. The catalyst disclosed by the invention is simple in preparation process, high in conversion rate, 1 and 4 -cyclohexanediol selectivity. The catalyst is low in manufacturing cost, easy to amplify and produce, and closer to industrial production.
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Paragraph 0022-0066
(2021/08/25)
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- Ceria supported Ru0-Ruδ+ clusters as efficient catalyst for arenes hydrogenation
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Selective hydrogenation of aromatic amines, especially chemicals such as aniline and bis(4-aminocyclohexyl)methane for non-yellowing polyurethane, is of particular interests due to the extensive applications. To conquer the existing difficulties in selective hydrogenation, the Ru0-Ruδ+/CeO2 catalyst with solid frustrated Lewis pairs was developed for aromatic amines hydrogenation with excellent activity and selectivity under relative milder conditions. The morphology, electronic and chemical properties, especially the Ru0-Ruδ+ clusters and reducible ceria were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), CO2 temperature programmed desorption (CO2-TPD), H2 temperature programmed reduction (H2-TPR), H2 diffuse reflectance Fourier transform infrared spectroscopy (H2-DRIFT), Raman, etc. The 2% Ru/CeO2 catalyst exhibited good conversion of 95% and selectivity greater than 99% toward cyclohexylamine. The volcano curve describing the activity and Ru state was found. Owning to the “acidic site isolation” by surrounding alkaline sites, condensation between the neighboring amine molecules could be effectively suppressed. The catalyst also showed good stability and applicability for other aromatic amines and heteroarenes containing different functional groups.
- Cao, Yanwei,Zheng, Huan,Zhu, Gangli,Wu, Haihong,He, Lin
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supporting information
p. 770 - 774
(2020/08/24)
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- Composite oxide supported double-transition metal catalyst used for fixed bed catalytic hydroquinone hydrogenation to prepare 1 and 4 - cyclohexanediol
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The double-transition metal-based catalyst is used for fixed bed catalytic hydroquinone hydrogenation preparation 1, 4 - cyclohexanediol, mainly taking composite oxide as a carrier and carrying double-transition metal as a catalyst, and is used for catalyzing hydroquinone hydrogenation to prepare 1 and 4 - cyclohexanediol in a fixed bed. To the catalyst, high selectivity 1 and 4 - cyclohexanediol can be obtained through high-efficiency benzenediol hydrogenation on a fixed bed. The catalyst prepared by the method is simple in process, low in cost, easy to amplify and beneficial to industrial production.
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Paragraph 0022-0069
(2021/08/25)
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- Carbon-supported Ni-based catalyst, preparation method thereof and 1-4 -cyclohexanediol prepared by catalyzing hydroquinone hydrogenation in fixed bed
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The invention provides 1-cyclohexanediol high-surface-area porous-4 - structure inorganic carbon carrier-supported-supported catalyst used for selective hydrogenation Ni of hydroquinone and a preparation method thereof. The catalyst includes a main active component. Auxiliaries and carriers or main active components and carriers. The support is an inorganic carbon support or an acid or base treatment. The main active component is Ni, Ni is 0.01-50 .0 wt % in the weight of the catalyst, and the content of other auxiliaries is 0 - 10.0 wt % of the catalyst. Ni And auxiliaries are supported on an inorganic carbon support by means of impregnation or the like, and the main active component is highly dispersed in the support. In fixed-bed reactors, under certain temperature and pressure and of the catalyst, hydroquinone can be converted to 1 and 4 - cyclohexanediol with high activity and selectivity.
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Paragraph 0021-0050
(2021/08/25)
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- Catalytic transfer hydrogenation of 4-O-5 models in lignin-derived compounds to cycloalkanes over Ni-based catalysts
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There is an urgent need to develop a selective hydrogenolysis of Caryl-O bonds in lignin to produce valued-added chemicals and fuels. Recently, hydrogen has been used in the hydrogenation reaction, which hides inevitable danger and is not economical. Therefore, isopropanol, as a hydrogen-donor solvent, is employed for aryl ether hydrogenolysis in lignin models over nickel supported on a carbon nanotube (CNT). Except for aromatic ether (4-O-5), the Ni/CNT catalyst is also found to be suitable for alkyl-aryl ether (α-O-4 and β-O-4) cleavage in control experiments. The physicochemical characterizations were carried out by means of H2-temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. The catalyst can be magnetically recovered and efficiently reused for five consecutive recycling tests in the transfer hydrogenation of aromatic ethers. A mechanism study indicated that the hydrogenolysis cleavage of the ether bond is the first step in the reaction process, and hydrogenation of aromatic rings is only a successive step in which phenol and benzene are intermediate states and are then further hydrogenated. Furthermore, it has been demonstrated that aryl groups play an important role in the hydrogenation of phenol in the competitive catalytic hydrogenation reaction of phenol.
- Chen, Changzhou,Liu, Peng,Xia, Haihong,Zhou, Minghao,Jiang, Jianchun
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p. 582 - 591
(2020/12/01)
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- Highly Efficient Cleavage of Ether Bonds in Lignin Models by Transfer Hydrogenolysis over Dual-Functional Ruthenium/Montmorillonite
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Cleavage of ether bonds is a crucial but challenging step for lignin valorization. To efficiently realize this transformation, the development of robust catalysts or catalytic systems is required. In this study, montmorillonite (MMT)-supported Ru (denoted as Ru/MMT) is fabricated as a dual-functional heterogeneous catalyst to cleave various types of ether bonds through transfer hydrogenolysis without using any additional acids or bases. The prepared Ru/MMT material is found to efficiently catalyze the cleavage of various lignin models and lignin-derived phenols; cyclohexanes (fuels) and cyclohexanols (key intermediates) are the main products. The synergistic effect between electron-enriched Ru and the acidic sites on MMT contributes to the excellent performance of Ru/MMT. Systematic studies reveal that the reaction proceeds through two possible reaction pathways, including the direct cleavage of ether bonds and the formation of intermediates with one hydrogenated benzene ring, for all examined types of ether bonds, namely, 4-O-5, α-O-4, and β-O-4.
- Xue, Zhimin,Yu, Haitao,He, Jing,Zhang, Yibin,Lan, Xue,Liu, Rundong,Zhang, Luyao,Mu, Tiancheng
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p. 4579 - 4586
(2020/06/21)
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- Selective hydrogenation of lignin-derived compounds under mild conditions
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A key challenge in the production of lignin-derived chemicals is to reduce the energy intensive processes used in their production. Here, we show that well-defined Rh nanoparticles dispersed in sub-micrometer size carbon hollow spheres, are able to hydrogenate lignin derived products under mild conditions (30 °C, 5 bar H2), in water. The optimum catalyst exhibits excellent selectivity and activity in the conversion of phenol to cyclohexanol and other related substrates including aryl ethers.
- Chen, Lu,Van Muyden, Antoine P.,Cui, Xinjiang,Laurenczy, Gabor,Dyson, Paul J.
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p. 3069 - 3073
(2020/06/17)
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- One-pot Synthesis of 4-Aminocyclohexanol Isomers by Combining a Keto Reductase and an Amine Transaminase
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The efficient multifunctionalization by one-pot or cascade catalytic systems has developed as an important research field, but is often challenging due to incompatibilities or cross-reactivities of the catalysts leading to side product formation. Herein we report the stereoselective preparation of cis- and trans-4-aminocyclohexanol from the potentially bio-based precursor 1,4-cyclohexanedione. We identified regio- and stereoselective enzymes catalyzing reduction and transamination of the diketone, which can be performed in a one-pot sequential or cascade mode. For this, we identified regioselective keto reductases for the selective mono reduction of the diketone to give 4-hydroxycyclohexanone. The system is modular and by choosing stereocomplementary amine transaminases, both cis- and trans-4-aminocyclohexanol were synthesized with good to excellent diastereomeric ratios. Furthermore, we identified an amine transaminase that produces cis-1,4-cyclohexanediamine with diastereomeric ratios >98 : 2. These examples highlight that the high selectivity of enzymes enable short and stereoselective cascade multifunctionalizations to generate high-value building blocks from renewable starting materials. Introduction.
- Sviatenko, Olha,Ríos-Lombardía, Nicolás,Morís, Francisco,González-Sabín, Javier,Venkata Manideep, Kollipara,Merdivan, Simon,Günther, Sebastian,Süss, Philipp,H?hne, Matthias
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p. 5794 - 5799
(2019/08/30)
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- Ru subnanoparticles on N-doped carbon layer coated SBA-15 as efficient Catalysts for arene hydrogenation
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The N-doped carbon layer coated SBA-15 support has been accomplished via a pyrolysis process. The ultra-low loading Ru nanoparticles (ca. 0.1 wt.%) was incorporated into the support by impregnation and the sequential reduction. The images of HAADF-STEM revealed that the Ru particles with sub-1-nm size (0.2-0.7 nm) were uniformly dispersed on the support. The ultrafine Ru particles displayed the excellent activity for the hydrogenation of olefins, arenes, phenol derivatives and heteroarenes in aqueous phase. The aliphatic or alicyclic compounds were produced selectively without the hydrogenolysis of C–O and C–N bonds. The high turnover frequency (TOF) values can reach up to 10,000 h?1. Notably, the activity of these catalysts improved dramatically with decreasing the sizes of Ru particles. Meanwhile, the N-doped carbon layer coating endowed the high stability of the Ru catalysts and prevented the leaching of the Ru species owning to the strong interaction between doped-N atoms and the ultrafine Ru particles. Overall, this work provides a highly attractive strategy to construct the supported sub-1-nm Ru particles utilized for the aqueous hydrogenation.
- Qian, Wei,Lin, Lina,Qiao, Yunxiang,Zhao,Xu, Zichen,Gong, Honghui,Li,Chen,Huang, Rong,Hou, Zhenshan
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- A novel cluster of C5-curcuminoids: design, synthesis, in vitro antiproliferative activity and DNA binding of bis(arylidene)-4-cyclanone derivatives based on 4-hydroxycyclohexanone scaffold
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A new series (6) of C5-curcuminoid derivatives (2E,6E-2,6-dibenzylidene-4-hydroxycyclohexanones) is described here with their evaluation for in vitro antiproliferative activities. Evaluation of 31 compounds against human A2780 (ovarian), C33A (cervix) and MDA-MB-231 (breast) cancer cell lines was performed to obtain structure activity relation data. The best performer was (2E,6E)-2,6-bis(3′-nitrobenzylidene)-4-hydroxycyclohexanone (6h) with IC50 values of 0.68?μM (A2780), 0.69?μM (C33A) and 0.92?μM (MDA-MB-231) compared to cisplatin with 1.30?μM, 3.69?μM and 19.13?μM, respectively. According to calculated physicochemical properties some members in series 6, namely (2E,6E)-2,6-bis[(4′-pyridinyl)methylene]-4-hydroxycyclohexanone (6p) [IC50 = 0.76?μM (A2780), 2.69?μM (C33A), 1.28?μM (MDA-MB-231)] seem to have improved bioavailability compared to curcumin. Selected members of series 6 were involved in circular dichroism spectroscopic measurements in order to determine their interaction with natural DNA. Based on these data, we conclude that these derivatives do not bind to DNA in vitro. A proposal is summarized based on mass spectrometric assessment for fingerprint analysis in biological research of such C5-curcuminoids.
- Huber, Imre,Zupkó, István,Gyovai, András,Horváth, Péter,Kiss, Eszter,Gulyás-Fekete, Gergely,Schmidt, János,Perjési, Pál
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p. 4711 - 4735
(2019/06/04)
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- Metal-Organic Framework Nodes Support Single-Site Nickel(II) Hydride Catalysts for the Hydrogenolysis of Aryl Ethers
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Herein we report that the Ti8-BDC (MIL-125) (BDC is 1,4-benzenecarboxylate) metal-organic framework (MOF) supports single-site solid NiII-hydride catalyst for the hydrogenolysis of aryl ethers containing α-O-4, β-O-4, and 4-O-5 linkages to exclusively afford hydrocarbons under mild conditions without the addition of a base. The catalytic activity of Ti8-BDC-NiH is highly dependent on the reduction of Ti8(μ2-O)8(μ2-OH)4 nodes. Density functional theory (DFT) calculations revealed two key steps of σ-bond metathesis in the catalytic cycle of Ti8-BDC-NiH catalyzed hydrogenolysis. This work highlights the potential of MOF-supported single-site catalysts in aryl ether bond scission and other processes for the efficient production of biofuels and chemical feedstocks.
- Song, Yang,Li, Zhe,Ji, Pengfei,Kaufmann, Michael,Feng, Xuanyu,Chen, Justin S.,Wang, Cheng,Lin, Wenbin
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p. 1578 - 1583
(2019/02/05)
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- A biomass phenolic compound catalytic hydrogenation method of synthesizing cyclohexyl alcohol compound (by machine translation)
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The invention relates to a biomass phenolic compound catalytic hydrogenation method of synthesizing cyclohexyl alcohol compound. It in order to load the noble metal palladium titanium dioxide as catalyst, biomass phenolic compound by catalytic hydrogenation synthesis of cyclohexyl alcohol compound, the obtained cyclohexyl alcohol compound can be used as fuel additives or pharmaceutical chemical intermediate, improving the utilization rate of renewable sources of energy, to relieve the energy crisis and the increasing importance attached to the problem of environmental pollution, its catalyst has simple preparation process, green environmental protection, does not pollute the environment, suitable for popularization and application. (by machine translation)
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Paragraph 0029; 0033
(2017/09/26)
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- A stable and practical nickel catalyst for the hydrogenolysis of C-O bonds
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The selective hydrogenolysis of C-O bonds constitutes a key step for the valorization of biomass including lignin fragments. Moreover, this defunctionalization process offers the possibility of producing interesting organic building blocks in a straightforward manner from oxygenated compounds. Herein, we demonstrate the reductive hydrogenolysis of a wide variety of ethers including diaryl, aryl-alkyl and aryl-benzyl derivatives catalyzed by a stable heterogeneous NiAlOx catalyst in the presence of a Lewis acid (LA). The special feature of this catalyst system is the formation of substituted cyclohexanols from the corresponding aryl ether.
- Cui, Xinjiang,Yuan, Hangkong,Junge, Kathrin,Topf, Christoph,Beller, Matthias,Shi, Feng
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p. 305 - 310
(2017/01/24)
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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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- Method for preparing 1,4-cyclohexanediol from p-benzoquinone through catalytic hydrogenation
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The invention relates to a method for preparing 1,4-cyclohexanediol from p-benzoquinone through catalytic hydrogenation. According to the method, palladium supported titanium dioxide is taken as a catalyst, p-benzoquinone is taken as a reaction raw material in an aqueous solution, and 1,4-cyclohexanediol is directly synthesized through direct catalytic hydrogenation. Water is taken as a solvent in both steps of reactions in the method, any other organic or inorganic solvents are not required to be added, a post-processing step for catalyst preparation is reduced, an operation process is simplified, green catalysis is realized, prevention of environmental pollution is realized, and the requirement for environmental protection is met; the reaction conditions are mild, post-processing is convenient, all that is required is to remove filter residues through filtering to obtain a product, the catalytic activity, the conversion rate and the selectivity are high, the yield can reach 98% or higher, the conversion degree can reach 100%, the industrial cost is low, the profit is large, and competition is facilitated.
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Paragraph 0015-0024
(2018/02/04)
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- Post-synthesized zirconium-containing Beta zeolite in Meerwein-Ponndorf-Verley reduction: Pros and cons
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Zr-Beta zeolite was prepared by a two-step post-synthesis method involving dealumination of Al-Beta followed by wet impregnation with Zr(NO3)4. Compared with Zr-Beta formed under fluoride-mediated hydrothermal conditions, the post-synthesized samples had smaller particle size and stronger Lewis acidity. The materials were tested as catalysts for Meerwein-Ponndorf-Verley reduction. In the reduction of 4-tert-butylcyclohexanone, it exhibited the same excellent stereoselectivity toward cis-4-tert-butylcyclohexanol (>99%) as the HF-synthesized Zr-Beta, but had a lower TOF. Because of the higher density of zirconium sites and the nanosized crystallites, it was a more effective catalyst for the MPV reduction of 1,4-cyclohexanedione, bulky aldehydes and aromatic ketones. However, it is more susceptible to poisoning by water adsorption because of its hydrophilic nature. The easily scalable synthesis method allows a faster preparation of metal-substituted Lewis acid zeolites, although differences in textural and chemical properties should be taken into consideration when the material is applied as a catalyst.
- Wang, Jie,Okumura, Kazu,Jaenicke, Stephan,Chuah, Gaik-Khuan
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p. 112 - 120
(2015/09/28)
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- Ruthenium Nanoparticles Stabilized in Cross-Linked Dendrimer Matrices: Hydrogenation of Phenols in Aqueous Media
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Novel catalysts consisting of ruthenium nanoparticles encapsulated in cross-linked matrices based on the poly(propylene imine) dendrimers of the 1st and 3rd generations have been synthesized with a narrow particle size distribution (3.8 and 1.0 nm, respectively). The resulting materials showed high activity for the hydrogenation of phenols in aqueous media (specific catalytic activity reached turnover frequencies of 2975h-1 with respect to hydrogen uptake). It has been shown that the use of water as a solvent leads to a 1.5 to 50-fold increase in the reaction rate depending upon the nature of the substrate. It has been established that unlike the traditional heterogeneous catalysts based on ruthenium, during the hydrogenation of dihydroxybenzenes, the hydrogenation rate decreases in the order: resorcinol>hydroquinoneacatechol. The maximum specific activity for resorcinol was a turnover frequency of 243150h-1 with respect to hydrogen uptake. The catalyst based on the dendrimer of the 3rd generation containing finer particles has significantly inferior activity to the catalyst based on the dendrimer of the 1st generation by virtue of steric factors, as well as the need for prereduction of the ruthenium oxide contained on the surface. These catalysts showed resistance to metal leaching and may be reused several times without loss of activity.
- Maximov, Anton,Zolotukhina, Anna,Murzin, Vadim,Karakhanov, Edward,Rosenberg, Edward
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p. 1197 - 1210
(2015/04/14)
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- Greener selective cycloalkane oxidations with hydrogen peroxide catalyzed by copper-5-(4-pyridyl)tetrazolate metal-organic frameworks
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Microwave assisted synthesis of the Cu(I) compound [Cu(μ4-4-ptz)]n [1, 4-ptz = 5-(4-pyridyl)tetrazolate] has been performed by employing a relatively easy method and within a shorter period of time compared to its sister compounds. The syntheses of the Cu(II) compounds [Cu3(μ3-4-ptz)4(μ2-N3)2(DMF)2]n·(DMF)2n (2) and [Cu(μ2-4-ptz)2(H2O)2]n (3) using a similar method were reported previously by us. MOFs 1-3 revealed high catalytic activity toward oxidation of cyclic alkanes (cyclopentane, -hexane and -octane) with aqueous hydrogen peroxide, under very mild conditions (at room temperature), without any added solvent or additive. The most efficient system (2/H2O2) showed, for the oxidation of cyclohexane, a turnover number (TON) of 396 (TOF of 40 h?1), with an overall product yield (cyclohexanol and cyclohexanone) of 40% relative to the substrate. Moreover, the heterogeneous catalytic systems 1-3 allowed an easy catalyst recovery and reuse, at least for four consecutive cycles, maintaining ca. 90% of the initial high activity and concomitant high selectivity.
- Martins, Luísa,Nasani, Rajendar,Saha, Manideepa,Mobin, Shaikh,Mukhopadhyay, Suman,Pombeiro, Armando
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p. 19203 - 19220
(2015/11/27)
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- Efficient room-temperature aqueous-phase hydrogenation of phenol to cyclohexanone catalyzed by Pd nanoparticles supported on mesoporous MMT-1 silica with unevenly distributed functionalities
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Efficient and selective aqueous-phase hydrogenation of phenol by a novel Pd catalyst supported on dually and selectively functionalized mesoporous MMT-1 silica nanoparticles has been developed. The catalyst features small (~1.1 nm) Pd nanoparticles surrounded by unevenly distributed nitrogen- or heteroatom-free organic groups in the helical mesopores and the presence of non-hydrogen-bonded isolated silanol groups on the mesopore surface. The catalyst exhibited superior conversion of phenol and high selectivity of cyclohexanone at room temperature under atmospheric pressure of hydrogen and remained highly active after ten catalytic runs. The catalyst was active for the aqueous-phase hydrogenation of a variety of mono- and dihydroxylated aromatic compounds. The green protocol with the designed catalyst would be practical for the hydrogenation of phenol and other derivatives.
- Lin, Chi-Jui,Huang, Shao-Hsien,Lai, Nien-Chu,Yang, Chia-Min
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p. 4121 - 4129
(2015/11/11)
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- Titanium nitride-nickel nanocomposite as heterogeneous catalyst for the hydrogenolysis of aryl ethers
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Lignin from biomass can become a sustainable source of aromatic compounds. Its depolymerization can be accomplished through hydrogenolysis, although the development of catalysts based on cheap and abundant metals is lacking. Herein, a sustainable composite based on titanium nitride and nickel is synthesized and employed as catalyst for the hydrogenolysis of aryl ethers as models for lignin. The catalytic activity of the new material during hydrogenation reactions is proven to be superior to that of either component alone. In particular, different aryl ethers could be efficiently converted under relatively mild conditions into aromatic compounds and cycloalkanes within minutes.
- Molinari, Valerio,Giordano, Cristina,Antonietti, Markus,Esposito, Davide
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supporting information
p. 1758 - 1761
(2014/03/21)
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- Mechanisms of selective cleavage of C-O bonds in di-aryl ethers in aqueous phase
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A route for cleaving the C-O aryl ether bonds of p-substituted H-, CH 3-, and OH- diphenyl ethers has been explored over Ni/SiO2 catalyst at very mild conditions (393 K, 0.6 MPa). The C-O bond of diphenyl ether is cleaved by parallel hydrogenolysis and hydrolysis (hydrogenolysis combined with HO* addition) on Ni. The rates as a function of H2 pressure from 0 to 10 MPa indicate that the rate-determining step is the C-O bond cleavage on Ni surface. H* atoms compete with the organic reactant for adsorption leading to a maximum in the rate with increasing H2 pressure. In contrast to diphenyl ether, hydrogenolysis is the exclusive route for cleaving a C-O bond of di-p-tolyl ether to form p-cresol and toluene. 4,4′-Dihydroxydiphenyl ether undergoes sequential surface hydrogenolysis, first to phenol and OC6H4OH * (adsorbed), which is then cleaved to phenol (C 6H4OH* with added H*) and H2O (O* with two added H*) in a second step. Density function theory supports the operation of this pathway. Notably, addition of H* to OC6H4OH * is less favorable than a further hydrogenolytic C-O bond cleavage. The TOFs of three diaryl ethers with Ni/SiO2 in water follow the order 4,4′-dihydroxydiphenyl ether 69molmolNi Surf-1h -1 > diphenyl ether 26molmolNi Surf-1h-1 > di-p-tolyl ether 1.3molmolNi Surf-1h-1, in line with the increasing apparent activation energies, ranging from 4,4′-dihydroxydiphenyl ether (93 kJ mol-1) -1) -1).
- He, Jiayue,Zhao, Chen,Mei, Donghai,Lercher, Johannes A.
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p. 280 - 290
(2014/04/03)
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- An efficient cleavage of the aryl ether C-O bond in supercritical carbon dioxide-water
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A simple and highly efficient Rh/C catalyzed route for the cleavage of the C-O bond of aromatic ether at 80 °C in the presence of 0.5 MPa of H 2 in the scCO2-water medium is reported; CO2 pressure and water play a key role under the tested conditions.
- Chatterjee, Maya,Ishizaka, Takayuki,Suzuki, Akira,Kawanami, Hajime
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supporting information
p. 4567 - 4569
(2013/06/04)
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- Continuous hydrogenation of hydroquinone to 1,4-cyclohexanediol over alkaline earth metal modified nickel-based catalysts
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Effects of different alkaline earth metals (Mg, Ca, Sr) on the nickel-based catalysts for the continuous hydrogenation of hydroquinone were studied, and it was found that the by-products, characterized by GC-MS analysis, were mainly composed of phenol and cyclohexanol. The conversion of hydroquinone was 99.2% and the selectivity to 1,4-cyclohexanediol was above 96.7% over a Ni-Sr/γ-Al2O3 catalyst at 160°C and 2.0 MPa hydrogen pressure. The high selectivity of the Ni-Sr/γ-Al 2O3 catalyst was ascribed to its weak acidity due to the formation of SrCO3, confirmed from XRD and NH3-TPD characterizations. Moreover, it was proposed that SrCO3 can disperse and stabilize the active Ni species, making the catalyst stable during the 90 h service life test.
- Bai, Guoyi,Li, Fei,Fan, Xinxin,Wang, Yalong,Qiu, Mande,Ma, Zheng,Niu, Libo
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scheme or table
p. 126 - 130
(2012/03/26)
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- High-performance gold-promoted palladium catalyst towards the hydrogenation of phenol with mesoporous hollow spheres as support
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A high-performance, gold-promoted Pd catalyst with mesoporous hollow silica spheres as support, PdAu/MHSS, was prepared using an impregnation-reduction approach. The catalyst showed 10 times higher activity than commercial Pd/C catalyst and 6 times higher activity than Pd/MHSS catalyst. The conversion of phenol was 100% within 30 min of reaction at 80 °C. The catalyst was characterized by XRD, XPS, and TEM, which revealed that its high performance may result from both the high dispersion of active components on the MHSS, caused by the addition of gold, and the interaction between palladium and gold.
- Yang, Xu,Du, Li,Liao, Shijun,Li, Yuexia,Song, Huiyu
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scheme or table
p. 29 - 33
(2012/03/26)
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- A tuneable bifunctional water-compatible heterogeneous catalyst for the selective aqueous hydrogenation of phenols
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A water-tolerant bifunctional heterogeneous catalyst is able to effectively catalyse the selective hydrogenation of phenol to cyclohexanone in water at atmospheric pressure and room temperature with >99.9% selectivity to cyclohexanone at phenol conversions >99.9%. The catalyst was found to be highly active and reusable, giving identical activities and selectivities after >5 uses. Moreover, this reported simple bifunctional catalyst is also able to hydrogenate a range of substituted phenols in high yields under the investigated aqueous conditions. Copyright
- Liu, Hongli,Li, Yingwei,Luque, Rafael,Jiang, Huanfeng
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supporting information; experimental part
p. 3107 - 3113
(2012/01/02)
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- Green and efficient procedure for the trimethylsilylation of hydroxy groups and their regeneration using sulfamic acid as recyclable catalyst
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Structurally diverse alcohols and phenols were efficiently transformed into their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) in the presence of catalytic amounts of sulfamic acid (SA) at room temperature under both acetonitrile and solvent-free conditions. Deprotection of these trimethylsilyl ethers to their parent alcohols and phenols was also achieved using this catalyst in water at room temperature. Copyright Taylor & Francis Group, LLC.
- Rostami, Amin,Ahmad-Jangi, Firoz,Zarebin, Mohammad Rezgar,Akradi, Jamal
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experimental part
p. 1500 - 1507
(2010/07/15)
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- Boric acid as cost-effective and recyclable catalyst for trimethylsilyl protection and deprotection of alcohols and phenols
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Boric acid has been used as a green, selective and recyclable catalyst for trimethysilylation of alcohols and phenols using hexamethyldisilazane in acetonitrile. Deprotection of trimethylsilyl ethers to their parent alcohols and phenols was also achieved using this catalyst in water at room temperature. The salient features of this methodology are cheap processing, mild acidity conditions, excellent yields of products and easy availability of the catalyst.
- Rostami, Amin,Akradi, Jamal,Ahmad-Jangi, Firoz
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experimental part
p. 1587 - 1592
(2010/11/04)
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- Identification and Counting of Carbonyl and Hydroxyl Functionalities in Protonated Bifunctional Analytes by Using Solution Derivatization Prior to Mass Spectrometric Analysis Via Ion-Molecule Reactions
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A mass spectrometric method has been developed for the identification of carbonyl and hydroxyl functional groups, as well as for counting the functional groups, in previously unknown protonated bifunctional oxygen-containing analytes. This method utilizes solution reduction before mass spectrometric analysis to convert the carbonyl groups to hydroxyl groups. Gas-phase ion-molecule reactions of the protonated reduced analytes with neutral trimethylborate (TMB) in a FT-ICR mass spectrometer give diagnostic product ions. The reaction sequence likely involves three consecutive steps, proton abstraction from the protonated analyte by TMB, addition of the neutral analyte to the boron reagent, and elimination of a neutral methanol molecule. The number of methanol molecules eliminated upon reactions with TMB reveals the number of hydroxyl groups in the analyte. Comparison of the reactions of the original and reduced analytes reveals the presence and number of carbonyl and hydroxyl groups in the analyte.
- Somuramasami, Jayalakshmi,Winger, Brian E.,Gillespie, Todd A.,Kenttaemaa, Hilkka I.
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experimental part
p. 773 - 784
(2011/11/12)
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- P-toluenesulfonyl chloride (p-TsCl)-catalyzed trimethylsilylation of hydroxyl groups using hexamethyldisilazane and their regeneration under mild conditions: The first example for catalytic application of p-toluenesulfonyl chloride
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The first catalytic application of p-toluenesulfonyl chloride (p-TsCl) for the efficient and selective trimethylsilylation of various types of hydroxyl groups with hexamethyldisilazane (HMDS) in dichloromethane and desilylation of these compounds in water is reported. The reactions were carried out at room temperature and were found to proceed in good to excellent yields.
- Khazaei, Ardeshir,Rostami, Amin,Mantashlo, Fatemeh
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experimental part
p. 2288 - 2296
(2010/04/06)
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- Hydrogenation of phenol in supercritical carbon dioxide catalyzed by palladium supported on Al-MCM-41: A facile route for one-pot cyclohexanone formation
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The hydrogenation of phenol has been carried out in supercritical carbon dioxide (scCO2) under very mild reaction conditions at the temperature of 50°C over palladium supported Al-MCM-41 (metal loading ~1%). This palladium catalyst is shown to be highly active and promotes the selective formation of cyclohexanone (~98%), an industrially important compound, in a "one-pot~ way. The effects of different variables like carbon dioxide and hydrogen pressure, reaction time and also silica/alumina ratio of the MCM-41 support along with palladium dispersion are presented and discussed. The pressure effect of carbon dioxide is significantly prominent in terms of conversion and cyclohexanone selectivity. Moreover, the silica/alumina ratio was also found to be an important parameter to enhance the effectiveness of the catalyst as it exhibits a remarkable increase in phenol conversion from 20.6% to 98.4% as the support changes from only silica MCM-41 to Al-MCM-41. A plausible mechanism for the hydrogenation of phenol to cyclohexanone over the palladium catalyst has been proposed. The proposition is vali-dated by transition state calculations using density functional theory (DFT), which reveal that cyclohexanone is a favorable product and stabilized by -1 over cyclohexanol in ScCO2 medium. Under similar reaction conditions, phenol hydrogenation was also carried out with rhodium, supported on Al-MCM-41. In contrast to the palladium catalyst, a mixture of cyclohexanone (57.8%) and cyclohexanol (42.2%) was formed. Detailed characterization by X-ray diffraction and transmission electron microscopy confirmed the presence of metal nanoparticles (palladium and rhodium) between 10-20 nm. Both the catalysts exhibit strikingly different product distributions in solventless conditions compared to scCO2. This method can also be successfully applied to the other hydroxylated aromatic compounds.
- Chatterjee,Kawanami,Sato,Chatterjee,Yokoyama,Suzuki
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experimental part
p. 1912 - 1924
(2011/03/17)
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- Chemoselective chemical and electrochemical deprotections of aromatic esters
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Alcohols can be easily and chemoselectively deprotected from the corresponding aromatic esters by using either SmI2/HMPA or by electrolysis In the presence of a proton source.
- Lam, Kevin,Marko, Istvan E.
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experimental part
p. 2752 - 2755
(2009/11/30)
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- Toluates: unexpectedly versatile reagents
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The mechanism of the monoelectronic reduction of aromatic esters has been investigated. The unexpected synthetic utility of the toluate moiety in the deoxygenation of alcohols and the allylation of ketones is also reported. Finally, the use of aromatic esters as robust, though easily removable, protecting groups is depicted.
- Lam, Kevin,Markó, István E.
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experimental part
p. 10930 - 10940
(2010/02/28)
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- Selective partial hydrogenation of hydroxy aromatic derivatives with palladium nanoparticles supported on hydrophilic carbon
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Selective hydrogenation of phenol to cyclohexanol in the aqueous phase was achieved using a new catalytic system based on palladium particles supported on hydrophilic carbon prepared by one-pot hydrothermal carbonisation. The Royal Society of Chemistry.
- Makowski, Philippe,Demir Cakan, Rezan,Antonietti, Markus,Goettmann, Frederic,Titirici, Maria-Magdalena
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p. 999 - 1001
(2008/09/21)
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- PROCESS FOR PRODUCTION OF 1,6-HEXANEDIOL
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A method is provided for obtaining highly pure 1,6-hexanediol in which the contents of impurities such as 1,4-cyclohexanediol, 1,5-hexanediol, 1,2-cyclohexanediol, 1,7-pentanediol, 1,5-pentanediol and high boiling point components are significantly reduced. This process for producing 1,6-hexanediol from cyclohexane comprises the steps of: (1) treating an aqueous extraction concentrate of a reaction mixture obtained by oxidation of cyclohexane with a lower alcohol to esterify monocarboxylic acids and dicarboxylic acids contained in the extract, and simultaneously remove and separate by distillation water, excess lower alcohols and carboxylic acid esters; (2) converting oligomer esters contained in the bottom liquid to carboxylic acid esters by depolymerizing the oligomer esters at a high temperature and high pressure in the presence of a lower alcohol and a catalyst; and (3) hydrogenating the carboxylic acid esters distilled off in the step (1) and the carboxylic acid esters obtained in the step (2) either respectively or collectively to convert to 1,6-hexanediol.
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Page/Page column 8
(2008/12/07)
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- METHOD FOR PRODUCTION OF 1,6-HEXANEDIOL WITH A PURITY IN EXCESS OF 99.5 %
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The invention relates to a method for the production of 1,6-hexanediol by hydrogenation of ester mixtures of dialkyl adipates and alkyl 6-hydroxycaproates, containing 1,4-cyclohexanedione and 4-hydroxycyclohexan-1-one as impurities, by a) removing excess alcohol and low-boilers from the obtained ester mixture in a first distillation stage (alcohol removal) b) separation of the sump product into an ester fraction essentially free of 1,4-cyclohexanediols and a fraction containing at least the greater part of the 1,4-cyclohexanediols in a second distillation stage, c) catalytic hydrogenation of the ester fraction essentially free of 1,4-cyclohexanediols (ester hydrogenation) and d) isolation of 1,6-hexanediol from the hydrogenation product in a known manner by a simple distillation step, characterised in that, before step a) and/or before step b), the ester mixture is selectively hydrogenated (purification hydrogenation).
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Page/Page column 8
(2008/06/13)
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- Facile deoxygenation of dicarbonyl compounds using a samarium diiodide-additive system
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The reduction of α- and β-dicarbonyl compounds was investigated with samarium diiodide in the presence of additive. Diketones and ketocarboxylic acids were easily reduced at room temperature to give the mono-alcohols in good to excellent yield, and ketoester afforded the saturated ester as the major product in moderate yield. These reductions containing the reductive deoxygenation can be rapidly performed under the facile and mild conditions by this method.
- Kamochi, Yasuko,Kudo, Tadahiro,Masuda, Toshinobu,Takadate, Akira
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p. 1017 - 1020
(2007/10/03)
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- METHOD FOR PRODUCING HEXANEDIOL
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A process for preparing 1,6-hexanediol from a carboxylic acid mixture comprising adipic acid, 6-hydroxycaproic acid and small amounts of 1,4-cyclohexanediols which is obtained as by-product in the oxidation of cyclohexane to cyclohexanone/cyclohexanol after water extraction of the reaction mixture followed by extraction with aqueous sodium hydroxide solution, by esterification of the acids and hydrogenation comprisesa) liberating the carboxylic acids from the alkaline extract by addition of a mineral acid,b) fractionating the organic phase comprising carboxylic acids to give a distillate comprising the low molecular weight monocarboxylic acids and a residue comprising adipic acid and 6-hydroxycaproic acid,c) reacting the monocarboxylic an dicarboxylic acids present in the aqueous dicarboxylic acid mixture with a low molecular weight alcohol to give the corresponding carboxylic esters,d) freeing the esterification mixture obtained of excess alcohol and low boilers in a first distillation step,e) fractionating the bottom product in a second distillation step to give an ester fraction essentially free of 1,4-cyclohexanediols and a fraction comprising at least the major part of the 1,4-cyclohexanediols,f) catalytically hydrogenating the ester fraction which is essentially free of 1,4-cyclohexanediols andg) isolating 1,6-hexanediol from the hydrogenation product in a manner known per se in a final distillation step.
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- Titanyl Acetylacetonate as an Efficient Catalyst for a Mild and Convenient Reduction of Carbonyl Compounds with NaBH4 under Aprotic Condition
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Titanyl acetylacetonate, TiO(acac)2, is used as an efficient catalyst for the reduction of carbonyl compounds with sodium borohydride under aprotic condition. Reduction reactions are performed in CH3CN and THF. The corresponding alcohols are obtained in high to excellent yields and the chemoselective reduction of aldehydes over ketones is achieved successfully.
- Zeynizadeh, Behzad
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p. 1220 - 1226
(2007/10/03)
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- Mild and efficient method for reduction of aldehydes and ketones with NaBH4 in the presence of Dowex1-x8
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Various aldehydes and ketones are reduced efficiently to alcohols with NaBH4/Dowex1-x8.
- Zeynizadeh, Behzad,Shirini, Farhad
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p. 335 - 339
(2007/10/03)
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- Modified hydroborate agent: (2,2′-bipyridyl)(tetrahydroborato)zinc complex, [Zn(BH4)2(bpy)], as a new, stable, efficient ligand-metal hydroborate and chemoselective reducing agent
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(2,2′-Bipyridyl)(tetrahydroborato)zinc complex, [Zn(BH4)2(bpy)], is a new white stable compound which has been used for efficient reduction of variety of carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and α, β-unsaturated carbonyl compounds (1,2-reduction) to their corresponding alcohols in acetonitrile at room temperature. Excellent chemoselectivity was also observed for the reduction of aldehydes over ketones with this reducing agent.
- Zeynizadeh, Behzad
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p. 317 - 326
(2007/10/03)
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- Ruthenium-catalyzed oxidation of alkanes with tert-butyl hydroperoxide and peracetic acid
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The ruthenium-catalyzed oxidation of alkanes with tert-butyl hydroperoxide and peracetic acid gives the corresponding ketones and alcohols highly efficiently at room temperature. The former catalytic system, RuCl2(PPh3)3-t-BuOOH, is preferable to the oxidation of alkylated arenes to give aryl ketones. The latter system, Ru/C-CH3CO3H, is suitable especially for the synthesis of ketones and alcohols from alkanes. The ruthenium-catalyzed oxidation of cyclohexane with CH3CO3H in trifluoroacetic acid/CH2Cl2 at room temperature gave cyclohexyl trifluoroacetate and cyclohexanone with 90% conversion and 90% selectivity (85:15). The mechanistic study indicates that these catalytic oxidations of hydrocarbons involve oxo-ruthenium species as key intermediates.
- Murahashi,Komiya,Oda,Kuwabara,Naota
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p. 9186 - 9193
(2007/10/03)
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- NOVEL AND FACILE REDUCTION OF PHENOL DERIVATIVES WITH SAMARIUM DIIODIDE-BASE SYSTEM
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Phenol was rapidly reduced with samarium diiodide-base system in the presence of protic solvent at room temperature to afford 3-cyclohexen-1-ol accompanied by cyclohexanol.The similar reduction of 4-methoxyphenol and 2-naphthol gave 4-hydroxycyclohexanone and 1,2,3,4-tetrahydro-2-naphthol in excellent yield, respectively.
- Kamochi, Yasuko,Kudo, Tadahiro
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p. 4169 - 4172
(2007/10/02)
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- Ruthenium-Catalyzed Isomerization of Allylic Alcohols to Saturated Ketones
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Highly efficient ruthenium-catalyzed isomerization of allylic alcohols to ketones have been developed.A dramatic rate enhancement by the presence of a catalytic amount of base was observed in the isomerization catalyzed by either RuCl2(PPh3) (3) or 2 (4).Dimetallic catalyst 5, which can itself serve as a base, led to a rapid reaction without the addition of extra base.
- Baeckvall, Jan-E.,Andreasson, Ulrika
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p. 5459 - 5462
(2007/10/02)
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- Polyetherimide bisphenol compositions
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Polyetherimide bisphenols and bischloroformates are prepared by the reaction of dianhydrides or certain bisimides with aminophenols or mixtures thereof with diamines. They are useful as intermediates for the preparation of cyclic heterocarbonates, which may in turn be converted to linear copolycarbonates. The bisphenols can also be converted to salts which react with cyclic polycarbonate oligomers to form block copolyetherimidecarbonates.
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- CYCLOALKANOL ESTERS OF DIHYDROLYSERGIC ACID USEFUL AS 5HT2 RECEPTOR ANTAGONISTS
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Cycloalkyl or ketocycloalkyl esters of 1-substituted-6-C 1-4 straight chain alkyl (or allyl)-ergoline-8β-carboxylic acids, useful as 5HT. sub.2 receptor antagonists.
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- Hydroboration. 76. Hydroboration of Cyclic Dienes with Representative Hydroborating Agents
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A detailed study was made of the hydroboration of cyclic dienes with representative hydroborating agents: borane-methyl sulfide (BMS), 9-borabicyclononane (9-BBN), disiamylborane (Sia2BH), dibromo-borane-methyl sulfide (Br2BH*SMe2), and dibromoborane (Br2BH). 1,4-Cyclohexadiene essentially undergoes monohydroboration with a stoichiometric amount of the representative hydroborating agents, whereas 1,5-cyclooctadiene gives the dihydroboration product predominantly.The rapid dimerization of 1,3-cyclopentadiene introduces a complication into its hydroboration.However, monomeric cyclopentadiene undergoes hydroboration primarily to the homoallylic derivative with little of the desired allylic product.Hydroboration of 1,3-cyclohexadiene with a stoichiometric amount of the hydroborating agent furnishes mainly the allylboranes, which upon treatment with acetaldehyde followed by oxidation, furnishes 1-(2-cyclohexenyl)-1-ethanol in good yield.Similary, hydroboration of 1,3-cycloheptadiene and 1,3-cyclooctadiene furnished dihydroborated products preferentially, with lower yields of the corresponding allylboranes, characterized as 1-(2-cycloheptenyl)-1-ethanol and 1-(2-cyclooctenyl)-1-ethanol, respectively, following reaction with acetaldehyde.
- Brown, Herbert C.,Bhat, Krishna S.
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p. 445 - 449
(2007/10/02)
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- Liquid phase ammoxidation of cyclohexanone and/or cyclohexanol
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Cyclohexanone and/or cyclohexanol can be ammoxidized in the liquid phase to heterocyclic compounds by contacting the cyclohexanone and/or cyclohexanol with various oxidation catalysts in the presence of molecular oxygen and ammonia.
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