- Efficient conversion of furfural into cyclopentanone over high performing and stable Cu/ZrO2 catalysts
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Currently, biomass transformation to produce high value-added chemicals and liquid biofuels is attracting more and more interest by the virtue of its importance in the sustainable development of human society. Herein, we reported the conversion of furfural (FFA) into cyclopentanone (CPO) in water over high performing and stable Cu/ZrO2 catalysts prepared by our developed one-pot reduction-oxidation method. It was demonstrated that surface structures and catalytic performances of catalysts could be delicately adjusted by varying the calcination temperatures for catalyst precursors. Especially, an appropriate calcination temperature of 500 °C could significantly enhance the interactions between surface Cu species and the ZrO2 support, thus greatly facilitating the formation of Cu+-O-Zr-like structure at the metal-support interface, and the resulting Cu/ZrO2 catalyst showed a superior catalytic performance with a high CPO yield of 91.3% under mild reaction conditions (i.e. a low hydrogen pressure of 1.5 MPa and 150 °C) to other metal oxides supported copper catalysts prepared by the conventional impregnation. It was revealed that in addition to surface acidic sites, surface Cu+/(Cu°+Cu+) ratio also played a key role in promoting the formation of CPO in the present Cu/ZrO2 catalytic system.
- Zhang, Yifeng,Fan, Guoli,Yang, Lan,Li, Feng
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- Catalytic Oxidation of Cyclopentene by O2 over Pd(II)-SBA-15 Complexes
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Abstract: Novel catalysts with Pd(II)-picolinamide complexes anchored into the channels of mesoporous material SBA-15 were prepared for chemical transformation of cyclopentene, and characterized in details. Spectra of 29Si NMR, 13C NMR and XPS revealed the organic ligands were grafted into the SBA-15 and Pd(II) complexes formed. Spacial diversity of the complexes, especially distances from –C=O to N on pyridyl cycles, may influence electronic distribution of conjugated system and further the catalytic activity. With the help of the newly synthesized catalytic materials, a new heterogeneous oxidation system was developed for selective catalytic transformation of cyclopentene to cyclopentanone with molecular oxygen as the sole oxidant. Analytic results of the reaction mixtures indicated that all catalysts exhibited high activity, while the cat.1 and cat.2 with 2-pyridinecarbonyl or 3-pyridinecarbonyl on the ligands gave better yields of cyclopentanone. 96.2% conversion of cyclopentene and 76.3% yied of cyclopentanone were achieved over the catalyst cat.2 under the conditions of 0.7?MPa O2, 323?K and 6?h reaction. In addition, the catalysts were also appealing for easy separation and recyclable property. Graphical Abstract: [Figure not available: see fulltext.] A new heterogeneous reaction system was developed for the catalytic oxidation of cyclopentene to cyclopentanone by molecular oxygen over novel catalysts. The synthesized catalysts are comprised of Pd(II)-picolinamide complexes anchored into the channels of SBA-15. The new system was efficient for the mentioned reaction, and the catalysts were reusable.
- Yue, Lumin,Wang, Zhenwei,Bao, Lele,Fu, Wei,Xu, Li,Li, Jun,Lu, Guanzhong
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- PREPARATION OF KETONES BY A NOVEL DECARBALKOXYLATION OF β-KETO ESTERS: STEREOELECTRONIC ASSISTANCE TO C-C BOND FISSION
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Reaction of β-keto esters with the sodium derivative of propane-1,2-diol in an excess of anhydrous propane-1,2-diol causes facile decarboxylation to ketones in excellent yields.
- Aneja, R.,Hollis, W. M.,Davies A. P.,Eaton, G.
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- Trinuclear triangular copper(II) clusters - Synthesis, electrochemical studies and catalytic peroxidative oxidation of cycloalkanes
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The reactions of CuII carboxylates (valerate, 2-methylbutyrate, hexanoate, heptanoate) with pyrazole (Hpz) in EtOH or EtOH/water solutions easily afford the triangular trinuclear copper derivatives [Cu 3(μ3-OH)(μ-pz)3(RCOO)2(L) x] [R = CH3(CH2)3, L = H 2O, x = 1 for 5; R = CH3CH2CH(CH3), L = EtOH, x = 2 for 6; R = CH3(CH2)4, L = EtOH, x = 1 for 7; R = CH3(CH2)5, L = EtOH, x = 1 for 8] as it has been previously found for R = H, L = Hpz, x = 2, (1); R = CH3, L = Hpz, x = 1, (2); R = CH3CH2, L = EtOH, x = 1, (3) and [Cu3(μ3-OH)(μ-pz) 3-(CH3(CH2)2COO)2(MeOH) (H2O)], (4). The trinuclear structure common to 5-8 has been assigned on the basis of magnetic susceptibility studies, ESI MS, IR and UV/Vis spectroscopy as well as 1H NMR measurements. The room temp. magnetic susceptibilities of 5-8 almost correspond to the presence of a single unpaired electron for each trinuclear unit. The IR spectra exhibit signals due to the bridging μ3-OH in accordance with what was observed in the spectra of 1-4. Solid-state and MeOH solution UV/Vis spectra show the same features previously reported for 1-4 and 1H NMR spectra of 1-8 show almost identical low field signals that can be assigned to pz- hydrogens. A detailed investigation of the supramolecular structures of 1 and 4 and the single-crystal X-ray study of the polymeric paddlewheel Cu(2-methylbutyrate) 2, A, are also reported. Electrochemical experiments show that in 1-8 the CuII ions can be reduced, in distinct steps, to CuI and Cu0. All the complexes act as catalysts or catalyst precursors for the efficient peroxidative oxidation, by aqueous hydrogen peroxide in acetonitrile and at room temp., of cycloalkanes RH (cyclohexane and cyclopentane) to the corresponding cyclic alcohols and ketones, with overall yields of up to 34% and TONs up to 42. Radical pathways involving the formation of alkyl hydroperoxides (ROOH) are involved. Wiley-VCH Verlag GmbH & Co. KGaA, 2009.
- Di Nicola, Corrado,Garau, Federica,Karabach, Yauhen Y.,Martins, Luisa M. D. R. S.,Monari, Magda,Pandolfo, Luciano,Pettinari, Claudio,Pombeiro, Armando J. L.
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- Synthesis of Unsaturated Spiroacetals, Cyclopentanone Derivatives, in the Presence of Natural Aluminosilicate Modified with Zirconium Cations
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Abstract: Conditions for the condensation of cyclopentanone and n-valeric aldehyde to 2-pentylidenecyclopentanone in the presence of an alcoholic solution of piperidine have been developed. The isomerization of the latter in a continuous-flow system over γ-Al2O3 yields 2-pentylcyclopent-2-en-1-one. The condensation of the obtained unsaturated ketones with ethane-1,2-diol in the presence of a heterogeneous catalyst, a natural aluminosilicate (perlite) modified with zirconyl sulfate, has been studied. The optimum conditions for the preparation of the corresponding unsaturated spiroacetals have been found. The synthesized compounds can be used as synthetic fragrances for different purposes.
- Abbasov,Alimardanov, Kh. M.,Abbaszade,Guseinova,Azimli
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- Kinetics and mechanisms of the thermal decomposition of 2-methyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane, and cyclopentanone ethylene ketal in the gas phase. Combined experimental and DFT study
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The kinetics of the gas-phase thermal decomposition of 2-methyl-1,3- dioxolane, 2,2-dimethyl-1,3-dioxolane, and cyclopentanone ethylene ketal were determined in a static system and the reaction vessel deactivated with allyl bromide. The decomposition reactions, in the presence of the free radical suppressor propene, are homogeneous, are unimolecular, and follow first-order law kinetics. The products of these reactions are acetaldehyde and the corresponding ketone. The working temperature range was 459-490 °C, and the pressure range was 46-113 Torr. The rate coefficients are given by the following Arrhenius equations: for 2-methyl-1,3-dioxolane, log k = (13.61 ± 0.12) - (242.1 ± 1.0)(2.303RT)-1, r = 0.9997; for 2,2-dimethyl-1,3-dioxolane, log k = (14.16 ± 0.14) - (253.7 ± 2.0)(2.303RT)-1, r = 0.9998; for cyclopentanone ethylene ketal, log k = (14.16 ± 0.14) - (253.7 ± 2.0)(2.303RT)-1, r = 0.9998. Electronic structure calculations using DFT methods B3LYP and MPW1PW91 with 6-31G(d,p), and 6-31++G(d,p) basis sets suggest that the decomposition of these substrates takes place through a stepwise mechanism. The rate-determining step proceeds through a concerted nonsynchronous four-centered cyclic transition state, and the elongation of the C-OCH3 bond in the direction C αδ+...OCH3δ- is predominant. The intermediate products of these decompositions are unstable, at the working temperatures, decomposing rapidly through a concerted cyclic six-centered cyclic transition state type of mechanism.
- Rosas, Felix,Lezama, Jesus,Mora, Jose R.,Maldonado, Alexis,Chuchani, Gabriel,Cordova, Tania
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- Regeneration of aldehydes and ketones from oximes using bis(trimethylsilyl)chromate
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Bis(trimethylsilyl) chromate transforms oximes of not only ketones but also aldehydes and 1,2-diketones to the corresponding carbonyl compounds, in high yields.
- Lee,Kwak,Hwang
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- Catalytic oxidation of cycloalkanes by porphyrin cobalt(II) through efficient utilization of oxidation intermediates
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The catalytic oxidation of cycloalkanes using molecular oxygen employing porphyrin cobalt(II) as catalyst was enhanced through use of cycloalkyl hydroperoxides, which are the primary intermediates in oxidation of cycloalkanes, as additional oxidants to further oxidize cycloalkanes in the presence of porphyrin copper(II), especially for cyclohexane, for which the selectivity was enhanced from 88.6 to 97.2% to the KA oil; at the same time, the conversion of cyclohexane was enhanced from 3.88 to 4.41%. The enhanced efficiency and selectivity were mainly attributed to the avoided autoxidation of cycloalkanes and efficient utilization of oxidation intermediate cycloalkyl hydroperoxides as additional oxidants instead of conventional thermal decomposition. In addition to cyclohexane, the protocol presented in this research is also very applicable in the oxidation of other cycloalkanes such as cyclooctane, cycloheptane and cyclopentane, and can serve as a applicable and efficient strategy to boost the conversion and selectivity simultaneously in oxidation of alkanes. This work also is a very important reference for the extensive application of metalloporphyrins in catalysis chemistry.
- Shen, Hai M.,Wang, Xiong,Guo, A. Bing,Zhang, Long,She, Yuan B.
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- Mild homogeneous oxidation and hydrocarboxylation of cycloalkanes catalyzed by novel dicopper(II) aminoalcohol-driven cores
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N-benzylethanolamine (Hbea) and triisopropanolamine (H3tipa) were applied as unexplored aminoalcohol N,O-building blocks for the self-assembly generation of two novel dicopper(II) compounds, [Cu2(μ-bea)2(Hbea)2](NO3)2 (1) and [Cu2(H3tipa)2(μ-pma)]·7H2O (2) {H4pma = pyromellitic acid}. These were isolated as stable and aqua-soluble microcrystalline products and were fully characterized by IR spectroscopy, ESI–MS(±), and single-crystal X-ray diffraction, the latter revealing distinct Cu2 cores containing the five-coordinate copper(II) centers with the {CuN2O3} or {CuNO4} environments. Compounds 1 and 2 were used as homogeneous catalysts for the mild oxidation of C5–C8 cycloalkanes to give the corresponding cyclic alcohols and ketones in up to 23% overall yields based on cycloalkane. The reactions proceed in aqueous acetonitrile medium at 50 °C using H2O2 as an oxidant. The effects of different reaction conditions were studied, including the type and loading of catalyst, amount and kind of acid promoter, and water concentration. Despite the fact that different acids (HNO3, H2SO4, HCl, or CF3COOH) promote the oxidation of alkanes, the reaction is exceptionally fast in the presence of a catalytic amount of HCl, resulting in the TOF values of up to 430 h?1. Although water typically strongly inhibits alkane oxidations due to the reduction of H2O2 concentration and lowering of the alkane solubility, in the systems comprising 1 and 2 we observed a significant growth (up to 5-fold) of an initial reaction rate in the cyclohexane oxidation on increasing the amount of H2O in the reaction mixture. The bond-, regio- and stereo-selectivity parameters were investigated in oxidation of different linear, branched, and cyclic alkane substrates. Both compounds 1 and 2 also catalyze the hydrocarboxylation of C5–C8 cycloalkanes, by CO, K2S2O8, and H2O in a water/acetonitrile medium at 60 °C, to give the corresponding cycloalkanecarboxylic acids in up to 38% yields based on cycloalkanes.
- Fernandes, Tiago A.,André, Vania,Kirillov, Alexander M.,Kirillova, Marina V.
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- Highly dispersed Co and Ni nanoparticles encapsulated in N-doped carbon nanotubes as efficient catalysts for the reduction of unsaturated oxygen compounds in aqueous phase
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N-Doped carbon nanotube-encapsulated metal nanoparticles are of great interest in heterogeneous catalysis owing to their improved mass transfer ability and superior stability. Herein, a facile one-pot pyrolysis approach using melamine as the carbon and nitrogen source was developed to fabricate metal nanoparticles embedded in bamboo-like N-doped carbon nanotubes (named as Co@NCNTs-600-800 and Ni@NCNTs-600-800). The optimized Co@NCNTs-600-800 catalyst exhibited outstanding activity in furfural (FAL) selective hydrogenation to furfuryl alcohol (FOL) or cyclopentanone (CPO) in aqueous media. High yields of FOL (100%) and CPO (75.3%) were achieved at 80 °C and 140 °C, respectively. Besides, this cobalt catalyst showed very good stability and recyclability during the reaction. The synergistic effect between metallic cobalt and N-doped carbon nanotubes was systematically investigated. In addition, the as-prepared Ni@NCNTs-600-800 catalyst also exhibited remarkable activity. Under optimal conditions (100 °C and 4 MPa H2 pressure), a maximum tetrahydrofurfuryl alcohol (THFOL) yield (99.5%) was obtained in the aqueous-phase hydrogenation of FAL. The research thus highlights new perspectives for non-noble metal-based N-doped carbon nanotube catalysts for biomass transformation.
- Gong, Wanbing,Chen, Chun,Zhang, Haimin,Wang, Guozhong,Zhao, Huijun
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- Solvent and substituent effects on the thermolysis of antimalarial fluorophenyl substituted 1,2.4-trioxanes
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The kinetics and mechanism of the thermal decomposition reaction of cis-6-(4-fluoropheny1)-5,6-[2-(4-fluorophenyl)-propylidene]-3, 3-tetramethylene-1,2,4-trioxacyclo-hexane (I) were investigated separately in n-hexane and in methanol solutions over the te
- Cafferata, Lazaro F. R.,Rimada, Ruben S.
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- Dehydration of 1,5-Pentanediol over Na-Doped CeO2 Catalysts
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The effects of CeO2 doped with Na on the dehydration of 1,5-pentanediol were studied by using a fixed-bed reactor at two different temperatures (350 and 400 °C) and atmospheric pressure. For characterization, BET surface area, hydrogen temperature-programmed reduction, CO2 temperature-programmed desorption, and diffuse reflectance infrared Fourier transform spectroscopy techniques were utilized. The conversion of the diol on CeO2 was found to depend on Na loading. The selectivity to the desired product (i.e., unsaturated alcohol) increased and the selectivity to undesired products (i.e., tetrahydropyran, tetrahydropyran-2-one, cyclopentanol and cylopentanone) decreased with increasing Na content on CeO2. The basicity of hydroxyl groups or surface oxygen on CeO2 was altered with the addition of Na, and controlled the dehydration reaction pathway.
- Gnanamani, Muthu Kumaran,Jacobs, Gary,Martinelli, Michela,Shafer, Wilson D.,Hopps, Shelley D.,Thomas, Gerald A.,Davis, Burtron H.
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- Hydrogenolysis of Furfuryl Alcohol to 1,2-Pentanediol Over Supported Ruthenium Catalysts
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Hydrogenolysis of the furan rings of furfural and furfuryl alcohol, which can be obtained from biomass, has attracted attention as a method for obtaining valuable chemicals such as 1,2-pentanediol. In this study, we examined the hydrogenolysis of furfuryl alcohol to 1,2-pentanediol over Pd/C, Pt/C, Rh/C, and various supported Ru catalysts in several solvents. In particular, we investigated the effects of combinations of solvents and supports on the reaction outcome. Of all the tested combinations, Ru/MgO in water gave the best selectivity for 1,2-pentanediol: with this catalyst, 42 % selectivity for 1,2-pentanediol was achieved upon hydrogenolysis of furfuryl alcohol for 1 h at 463 K. In contrast, reaction in water in the presence of Ru/Al2O3 afforded cyclopentanone and cyclopentanol by means of hydrogenation and rearrangement reactions.
- Yamaguchi, Aritomo,Murakami, Yuka,Imura, Tomohiro,Wakita, Kazuaki
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- Highly selective hydrogenation of furfural to tetrahydrofurfuryl alcohol over MIL-101(Cr)-NH2 supported Pd catalyst at low temperature
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An efficient heterogeneous catalyst, Pd@MIL-101(Cr)-NH2, is prepared through a direct pathway of anionic exchange followed by hydrogen reduction with amino-containing MIL-101 as the host matrix. The composite is thermally stable up to 350 °C and the Pd nanoparticles uniformly disperse on the matal organic framework (MOF) support, which are attributed to the presence of the amino groups in the frameworks of MIL-101(Cr)-NH2. The selective hydrogenation of biomass-based furfural to tetrahydrofurfuryl alcohol is investigated by using this multifunctional catalyst Pd@MIL-101(Cr)-NH2 in water media. A complete hydrogenation of furfural is achieved at a low temperature of 40 °C with the selectivity of tetrahydrofurfuryl alcohol close to 100%. The amine-functionalized MOF improves the hydrogen bonding interactions between the intermediate furfuryl alcohol and the support, which is conducive for the further hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol in good coordination with the metal sites.
- Yin, Dongdong,Ren, Hangxing,Li, Chuang,Liu, Jinxuan,Liang, Changhai
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- Hydrogenation of Furfural to Cyclopentanone under Mild Conditions by a Structure-Optimized Ni?NiO/TiO2 Heterojunction Catalyst
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The catalytic conversion of biomass-derived furfural (FFA) into cyclopentanone (CPO) in aqueous solution is an important pathway to obtain sustainable resources. However, the conversion and selectivity under mild conditions are still unsatisfactory. In this study, a catalyst consisting of Ni?NiO heterojunction supported on TiO2 with optimized composition of anatase and rutile (Ni?NiO/TiO2-Re450) is prepared by pyrolysis at 450 °C. With Ni?NiO/TiO2-Re450, as catalyst, complete conversion of FFA and 87.4 % yield of CPO are achieved under mild reaction conditions (1 MPa, 140 °C, 6 h). 95.4 % FFA conversion is retained up to the fifth run, indicating the high stability of the catalyst. Multiple characterizations, control experiments, and theoretical calculations demonstrate that the good catalytic performance of Ni?NiO/TiO2-Re450 can be attributed to a synergistic effect of the Ni?NiO heterojunction and the TiO2 support. This low-cost catalyst may expedite the catalytic upgrading and practical application of biomass-derived chemicals.
- Chen, Shuo,Qian, Ting-Ting,Ling, Li-Li,Zhang, Wenhua,Gong, Bing-Bing,Jiang, Hong
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- Catalytic hydrogenation of furfural to tetrahydrofurfuryl alcohol using competitive nickel catalysts supported on mesoporous clays
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Nickel catalysts supported on mesoporous clays with different acid properties, such as montmorillonite MK-10, Al-pillared montmorillonite, mesoporous Na-saponite and mesoporous H-saponite, were prepared, characterized and tested for the hydrogenation of furfural to tetrahydrofurfuryl alcohol (THFA). Clays were also modified introducing basicity through magnesium oxide in different amounts. Catalysts with higher acidity or low amounts of metallic centres favoured deactivation and/or selectivity to the non-desired products. Interestingly, the addition of MgO both neutralized the acidity of the montmorillonite supports and improved the hydrogenation of the furanic ring, resulting in higher selectivity to THFA. The best catalyst was the one prepared with montmorillonite MK-10 covered by 30 wt% of magnesium oxide and with 8.8 % of the Ni metal phase achieving total conversion and total selectivity to THFA. The activity of this catalyst was maintained after several reuses.
- Sunyol,English Owen,González,Salagre,Cesteros
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- Ruthenium Trichloride Catalyst in Water: Ru Colloids versus Ru Dimer Characterization Investigations
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An easy-to-prepare ruthenium catalyst obtained from ruthenium(III) trichloride in water demonstrates efficient performances in the oxidation of several cycloalkanes with high selectivity toward the ketone. In this work, several physicochemical techniques were used to demonstrate the real nature of the ruthenium salt still unknown in water and to define the active species for this Csp3-H bond functionalization. From transmission electron microscopy analyses corroborated by SAXS analyses, spherical nanoobjects were observed with an average diameter of 1.75 nm, thus being in favor of the formation of reduced species. However, further investigations, based on X-ray scattering and absorption analyses, showed no evidence of the presence of a metallic Ru-Ru bond, proof of zerovalent nanoparticles, but the existence of Ru-O and Ru-Cl bonds, and thus the formation of a water-soluble complex. The EXAFS (extended X-ray absorption fine structure) spectra revealed the presence of an oxygen-bridged diruthenium complex [Ru(OH)xCl3-x]2(μ-O) with a high oxidation state in agreement with catalytic results. This study constitutes a significant advance to determine the true nature of the RuCl3·3H2O salt in water and proves once again the invasive nature of the electron beam in microscopy experiments, routinely used in nanochemistry.
- Lebedeva, Anastasia,Albuquerque, Brunno L.,Domingos, Josiel B.,Lamonier, Jean-Fran?ois,Giraudon, Jean-Marc,Lecante, Pierre,Denicourt-Nowicki, Audrey,Roucoux, Alain
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- Identification, characterization, and application of three enoate reductases from Pseudomonas putida in in vitro enzyme cascade reactions
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Enoate reductases are versatile enzymes for the enantio- and regioselective addition of hydrogen to double bonds. We identified three EREDs (XenA, XenB, NemA) from Pseudomonas putida ATCC 17453 through a sequence motif search. In addition to cloning, functional expression, and biochemical characterization of these enzymes, the enoate reductases were also applied in enzyme cascade reactions in combination with a Baeyer-Villiger monooxygenase and an alcohol dehydrogenase to produce lactones. Good things come in threes: The identification, cloning, expression, and characterization of three enoate reductases from Pseudomonas putida reveal broad substrate scope and high stereoselectivities. Furthermore, the enoate reductases could be integrated into cascade reactions together with an alcohol dehydrogenase and a Baeyer-Villiger monooxygenase.
- Peters, Christin,Koelzsch, Regina,Kadow, Maria,Skalden, Lilly,Rudroff, Florian,Mihovilovic, Marko D.,Bornscheuer, Uwe T.
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- Simultaneous Upgrading of Furanics and Phenolics through Hydroxyalkylation/Aldol Condensation Reactions
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The simultaneous conversion of cyclopentanone and m-cresol has been investigated on a series of solid-acid catalysts. Both compounds are representative of biomass-derived streams. Cyclopentanone can be readily obtained from sugar-derived furfurals through Piancatelli rearrangement under reducing conditions. Cresol represents a family of phenolic compounds, typically obtained from the depolymerization of lignin. In the first biomass conversion strategy proposed here, furfural is converted in high yields and selectivity to cyclopentanone (CPO) over metal catalysts such as Pd-Fe/SiO2 at 600 psi (～4.14 MPa) H2 and 150 °C. Subsequently, CPO and cresol are further converted through acid-catalyzed hydroxyalkylation. This C?C coupling reaction may be used to generate products in the molecular weight range that is appropriate for transportation fuels. As molecules beyond this range may be undesirable for fuel production, a catalyst with a suitable porous structure may be advantageous for controlling the product distribution in the desirable range. If Amberlyst resins were used as a catalyst, C12–C24 products were obtained whereas when zeolites with smaller pore sizes were used, they selectively produced C10 products. Alternatively, CPO can undergo the acid-catalyzed self-aldol condensation to form C10 bicyclic adducts. As an illustration of the potential for practical implementation of this strategy for biofuel production, the long-chain oxygenates obtained from hydroxyalkylation/aldol condensation were successfully upgraded through hydrodeoxygenation to a mixture of linear alkanes and saturated cyclic hydrocarbons, which in practice would be direct drop-in components for transportation fuels. Aqueous acidic environments, which are typically encountered during the liquid-phase upgrading of bio-oils, would inhibit the efficiency of base-catalyzed processes. Therefore, the proposed acid-catalyzed upgrading strategy is advantageous for biomass conversion in terms of process simplicity.
- Bui, Tuong V.,Sooknoi, Tawan,Resasco, Daniel E.
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- Effect of Ni Metal Content on Emulsifying Properties of Ni/CNTox Catalysts for Catalytic Conversion of Furfural in Pickering Emulsions
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Ni/CNTox catalysts with variable metal content have been prepared to investigate their emulsifying and catalytic properties for the liquid-phase conversion of furfural. The solid catalysts and emulsions were analyzed by several characterization techniques. The catalytic activity linearly increased with increasing Ni content (up to 10 wt.%) before dropping down again for a Ni content of 15 wt.%. The loss of catalytic activity was attributed to larger emulsion droplets formed by the inhibition of hydrophilic sites. All Ni/CNTox catalysts were highly selective to cyclopentanone as a main product, while several changes regarding secondary products were observed. Ni/CNTox catalysts with a Ni content up to 10 wt.% favor the formation of levulinic acid, while catalysts with a Ni content of 15 wt.% were selective to tetrahydrofurfuryl alcohol. This was attributed to an inhibition of the acid sites thus favoring the catalyst's hydrogenation capacity.
- Herrera,Pinto-Neira,Fuentealba,Sepúlveda,Rosenkranz,García-Fierro,González,Escalona
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- Aqueous phase hydrogenation of furfural to furfuryl alcohol over Pd-Cu catalysts
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A series of Pd, Cu and bimetallic Pd-Cu catalysts with different metals loadings on various supports were prepared for the selective hydrogenation of furfural to furfuryl alcohol in water as a solvent. In the literature are almost missing the data about the selective hydrogenation of furfural in water. Among the catalysts screened, bimetallic Pd-Cu catalysts supported on MgO and Mg(OH)2 prepared by electroless plating method showed the highest conversion and selectivity to furfuryl alcohol. The catalysts 5% Pd-5% Cu supported on MgO or Mg(OH)2 exhibited at 110°C and 0.6 MPa of hydrogen complete conversion of furfural and higher than 98% selectivity toward furfuryl alcohol after 80 min of reaction. The complete conversion of furfural and the same selectivity could be achieved after five catalytic cycles without extra catalyst treatment or reactivation. Based on physico-chemical characterization the role of Cu loading on the performance of bimetallic Pd-Cu catalysts was discussed. We assume that over Pd-Cu catalyst prepared by electroless plating method on the surface are present monometallic Pd0 sites and closely interacting bimetallic Pd0-Cu2O catalytic sites. The Cu+ sites participate on activation of CO group in furfural. The interaction between active metal species and the support also influence the performance of catalyst.
- Fulajtárova, Katarína,Soták, Tomá?,Hronec, Milan,Vávra, Ivo,Dobro?ka, Edmund,Omastová, Mária
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- Wacker-type oxidation of cyclopentene under dioxygen atmosphere catalyzed by Pd(OAc)2/NPMoV on activated carbon
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Wacker-type oxidation of cyclopentene to cyclopentanone under dioxygen atmosphere was successfully achieved by the use of Pd(OAc)2 and molybdovanadophosphate supported on activated carbon, [Pd(OAc)2-NPMoV/C], catalyst. Thus, the reaction of cyclopentene under O2 (1 atm) in aqueous acetonitrile acidified by CH3SO3H in the presence of [Pd(OAc)2-NPMoV/C] at 50°C produced cyclopentanone in 85% yield along with a small amount of cyclopentenone (1%).
- Kishi, Arata,Higashino, Takashi,Sakaguchi, Satoshi,Ishii, Yasutaka
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- One-Step Encapsulation of Bimetallic Pd–Co Nanoparticles Within UiO-66 for Selective Conversion of Furfural to Cyclopentanone
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Abstract: The design of efficient catalysts is of important significance for the transformation of biomass into chemicals. In this work, bimetallic Pd–Co nanoparticles were encapsulated within UiO-66 to form a core–shell Pd–Co@UiO-66 catalyst via a facile one-step strategy. The as-synthesized Pd–Co@UiO-66 catalysts were characterized and applied to the selective hydrogenation of furfural (FUR) to cyclopentanone (CPO). Compared with the monometallic Pd@UiO-66, the Pd–Co@UiO-66 could demonstrate excellent performance with 96% CPO selectivity and 99% FUR conversion at 120?°C under 3?MPa H2 pressure for 12?h. It was found that trace Co had synergetic and promoting effects on the catalytic performance. The core–shell catalysts showed more outstanding recyclability than the supported catalysts, which could maintain high CPO yield after 5th runs. Graphic Abstract: [Figure not available: see fulltext.].
- Wang, Yanling,Liu, Cun,Zhang, Xiongfu
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- Characterization and reactivity of γ-Al2O3 supported Pd-Cu bimetallic nanocatalysts for the selective oxygenization of cyclopentene
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In this work, Pd-Cu/γ-Al2O3 is prepared by the impregnation method and investigated for selective oxygenization of cyclopentene to cyclopentanone. A series of bimetallic Pd-Cu/γ-Al2O3 nanocatalysts were prepared and the structures characterized by XRD, XPS and TEM. We determined that the obtained Pd-Cu/γ-Al2O3 (molar ratio Pd:Cu = 5:1) was an efficient catalyst for the oxygenization of cyclopentene to cyclopentanone with >95% selectivity and >85% conversion (100 °C, 1 MPa initial O2 pressure, 7 h).
- Liu, Wei-Wei,Feng, Yi-Si,Wang, Guang-Yu,Jiang, Wei-Wei,Xu, Hua-Jian
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- Conversion of furfural to cyclopentanol on Cu/Zn/Al catalysts derived from hydrotalcite-like materials
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The Cu/Zn/Al catalysts, prepared from the calcination and reduction of hydrotalcite-like compounds containing Cu, Zn and Al, were introduced to the aqueousphase hydrogenation of furfural from pyrolysis of biomass. And the target production was cyclopentanol. The catalyst performance was investigated from the aspects of catalyst composition, calcination temperature, reaction temperature, initial hydrogen pressure and reaction time. Among all the variables, calcination temperature had a profound impact on the catalyst performance. The furfural conversion was up to nearly 100 % with a cyclopentanol yield of 84 %, when the hydrogenation reaction was carried out over 600 °C calcined hydrotalcite catalyst with a Cu/Zn/Al molar ratio of 6:9:5 at 150 °C with an initial hydrogen pressure of 4 MPa for 10 h. The features of Cu/Zn/Al catalysts were investigated via XRD, XPS, TPR, SEM and BET.
- Wang, Yuan,Zhou, Minghao,Wang, Tongzhen,Xiao, Guomin
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- Influence of furanic polymers on selectivity of furfural rearrangement to cyclopentanone
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The influence of furanic polymers upon the activity and selectivity of Ni, Pd, Pt catalysts in rearrangement of furfural to cyclopentanone, and its consecutive hydrogenation to cyclopentanol in an aqueous phase has been studied. The coverage of surface of
- Hronec, Milan,Fulajtárova, Katarina,Mi?u?ik, Matej
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- Sorption and catalysis by robust microporous metalloporphyrin framework solids
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Two isostructural metalloporphyrin framework solids have been synthesized. Both frameworks contains manganese(III) metal complexes of trans-dicarboxylateporphyrins whose peripheralcarboxylates coordinate the edges of tetrahedral Zn4O+6 clusters; the two metalloporphyrins explored are Mn(III) and Co(II). The cubic interpenetrated frameworks have 72% free volume and 4 × 7 ? averaged size pores. The evacuated frameworks are robust and retain a structure open to the sorption of substrates with medium polarity. The manganese porphyrin framework catalyzes the hydroxylation of cyclic and linear alkanes with iodosylbenzene as oxidant in a size-and polarity-selective manner. In addition, the catalysis was found to occur within the pores, making this a rare case of porphyrin framework solid with interior catalysis.
- Smithenry, Dennis W.,Wilson, Scott R.,Nakagaki, Shirley,Suslick, Kenneth S.
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- Reductive Elimination of Ketones from Ruthenium(II) Complexes
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Complexes (R = aryl or alkyl) decompose at room temperature in CHCl3 or Me2CO solution to yield the ketones R2CO.Decomposition is intramolecular, since the complexes yield only the unsymmetrical ketones RR'CO, and the disappearance of follows simple first-order kinetics.The acyl complex also decomposes in CHCl3 solution to give (4-MeC6H4)2CO, but the decomposition is inhibited by free Me3CNC.It is believed that the ketones are formed by reductive elimination from .A ruthenium(0) product could not be isolated, but the ruthenium(II) complex Ru(CO)ClC6H4Me>(PMe2Ph)2> was obtained when the decomposition of in CHCl3 was carried out at higher temperatures.
- Saunders, David R.,Mawby, Roger J.
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- Catalytic Allylation of 1-Trimethylsilyloxycyclopent-1-ene into 2-Allylcyclopentanone over Palladium supported on Silica
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1-Trimethylsilyloxycyclopent-1-ene can be catalytically converted into 2-allylcyclopentanone by its reaction with diallyl carbonate over palladium supported on silica.
- Baba, T.,Nakano, K.,Nishiyama, S.,Tsurya, S.,Masai, M.
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- A one-pot synthesis of 1,6,9,13-tetraoxadispiro(4.2.4.2)tetradecane by hydrodeoxygenation of xylose using a palladium catalyst
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In an effort to expand the number of biobased chemicals available from sugars, xylose has been converted to 1,6,9,13-tetraoxadispiro(4.2.4.2)tetradecane in a one-pot reaction using palladium supported on silica-alumina as the catalyst. The title compound is produced in 35-40% yield under 7 MPa H2 pressure at 733 K using 3-10 wt%Pd on silica-alumina catalyst. It is isolated using a combination of liquid-liquid extractions and flash chromatography. This dimer can be converted to its monomer, 2-hydroxy-(2-hydroxymethyl)tetrahydrofuran, which ring opens under acid conditions to 1,5-dihydroxy-2-pentanone. This diol can then be esterified with vinylacetate in phosphate buffer to produce 1,5-bis(acetyloxy)-2-pentanone which is an inhibitor of mammalian 11β-hydroxysteroid dehydrogenase 1. 1H and 13C nmr spectra of each of these species are reported. The single crystal X-ray structure of the title compound is also reported. These data were collected in a temperature range of 100 K-273 K and show a solid state phase change from triclinic to monoclinic between 175 K and 220 K without a conformational change.
- Jackson, Michael A.,Blackburn, Judith A.,Price, Neil P.J.,Vermillion, Karl E.,Peterson, Steven C.,Ferrence, Gregory M.
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- Copper(II) Coordination Polymers Self-Assembled from Aminoalcohols and Pyromellitic Acid: Highly Active Precatalysts for the Mild Water-Promoted Oxidation of Alkanes
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Three novel water-soluble 2D copper(II) coordination polymersˉ[{Cu2(μ2-dmea)2(H2O)}2(μ4-pma)]n·4nH2O (1), [{Cu2(μ2-Hedea)2}2(μ4-pma)]n·4nH2O (2), and [{Cu(bea)(Hbea)}4(μ4-pma)]n·2nH2O (3)ˉwere generated by an aqueous medium self-assembly method from copper(II) nitrate, pyromellitic acid (H4pma), and different aminoalcohols [N,N-dimethylethanolamine (Hdmea), N-ethyldiethanolamine (H2edea), and N-benzylethanolamine (Hbea)]. Compounds 2 and 3 represent the first coordination polymers derived from H2edea and Hbea. All the products were characterized by infrared (IR), electron paramagnetic resonance (EPR), and ultraviolet-visible light (UV-vis) spectroscopy, electrospray ionization-mass spectroscopy (ESI-MS(±)), thermogravimetric and elemental analysis, and single-crystal X-ray diffraction (XRD), which revealed that their two-dimensional (2D) metal-organic networks are composed of distinct dicopper(II) or monocopper(II) aminoalcoholate units and μ4-pyromellitate spacers. From the topological viewpoint, the underlying 2D nets of 1-3 can be classified as uninodal 4-connected layers with the sql topology. The structures of 1 and 2 are further extended by multiple intermolecular hydrogen bonds, resulting in three-dimensional (3D) hydrogen-bonded networks with rare or unique topologies. The obtained compounds also act as highly efficient precatalysts for the mild homogeneous oxidation, by aqueous H2O2 in acidic MeCN/H2O medium, of various cycloalkanes to the corresponding alcohols and ketones. Overall product yields up to 45% (based on cycloalkane) were attained and the effects of various reaction parameters were investigated, including the type of precatalyst and acid promoter, influence of water, and substrate scope. Although water usually strongly inhibits the alkane oxidations, a very pronounced promoting behavior of H2O was detected when using the precatalyst 1, resulting in a 15-fold growth of an initial reaction rate in the cyclohexane oxidation on increasing the amount of H2O from ～4 M to 17 M in the reaction mixture, followed by a 2-fold product yield growth.
- Fernandes, Tiago A.,Santos, Carla I. M.,André, Vania,K?ak, Julia,Kirillova, Marina V.,Kirillov, Alexander M.
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- Aqueous phase hydrogenation of furfural to tetrahydrofurfuryl alcohol on alkaline earth metal modified Ni/Al2O3
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Al2O3 modified by alkaline earth metals M-Al2O3 (M = Mg, Ca, Sr, Ba) was synthesised by coprecipitation method. The nickel-based catalysts supported by M-Al2O3 were prepared by impregnation method. The catalysts were characterized by TEM, N2 adsorption/desorption, XRD, H2-TPR, NH3-TPD and XPS, and used for the direct hydrogenation of furfural to tetrahydrofurfuryl alcohol (THFA) in water. The reaction was demonstrated to proceed through furfuryl alcohol as an intermediate. The modification of Al2O3 by alkaline earth metals has a significant effect on the activity and selectivity of THFA. A high yield of THFA was obtained over Ni/Ba-Al2O3 under optimized conditions. Moreover, the catalyst is recyclable and reusable at least four times without significant loss of the conversion of furfural and selectivity of THFA.
- Yang, Yanliang,Ma, Jiping,Jia, Xiuquan,Du, Zhongtian,Duan, Ying,Xu, Jie
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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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- Synthesis of azasilacyclopentenes and silanols: Via Huisgen cycloaddition-initiated C-H bond insertion cascades
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An unusual transition metal-free cascade reaction of alkynyl carbonazidates was discovered to form azasilacyclopentenes. Mild thermolysis afforded the products via a series of cyclizations, rearrangements, and an α-silyl C-H bond insertion (rather than the more common Wolff rearrangement, 1,2-shift, or β-silyl C-H insertion) to form silacyclopropanes. A mechanistic proposal for the sequence was informed by control experiments and the characterization of reaction intermediates. The substrate scope and post-cascade transformations were also explored.
- Shih, Jiun-Le,Jansone-Popova, Santa,Huynh, Christopher,May, Jeremy A.
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- Selective transformation of furfural to cyclopentanone
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An entirely new route for highly selective preparation of cyclopentanone from furfural is described. It has been found that furfural dissolved in water is converted to cyclopentanone with very high selectivity at temperatures above 140 °C and hydrogen pressures > 30 bar. The selectivity of this reaction is strongly influenced by the heterogeneous catalyst and depends on the reaction conditions. Prolongation of the reaction time leads to the hydrogenation of cyclopentanone to cyclopentanol. If instead of water other solvents are used, the main products of reaction are well known hydrogenated derivatives of furfural, i.e. furfuryl alcohol, tetrahydrofurfuryl alcohol, 2-methylfuran and 2-methyltetrahydrofuran. In the presence of 5% Pt/C catalyst, 76.50 mol% yield of cyclopentanone (81.32 mol% comprehensive yield of cyclopentanone and cyclopentanol) is obtained after 30 min of reaction at 160 °C and a hydrogen pressure of 80 bar.
- Hronec, Milan,Fulajtarová, Katarina
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- Hydrogenative Ring-Rearrangement of Biobased Furanic Aldehydes to Cyclopentanone Compounds over Pd/Pyrochlore by Introducing Oxygen Vacancies
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Upgrading furanic aldehydes (such as furfural or 5-hydroxymethyl furfural) to cyclopentanone compounds (such as cyclopentanone or 3-hydroxymethyl cyclopentanone) is of great significance for the synthesis of high-value chemicals and biomass utilization. Developing an efficient reduced metal/acidic support with Lewis acidity is the key to facilitating the carbonyl hydrogenation and hydrolysis steps in the hydrogenative ring-rearrangement reaction. Herein, three pure Lewis acidic pyrochlore supports of the form A2B2O7 (La2Sn2O7, Y2Sn2O7, and Y2(Sn0.7Ce0.3)2O7-δ) with the same crystal structures and different metals are synthesized. The Lewis acidity and the surface properties of the pyrochlore can be tuned by inserting different kinds of A and B site metals. After impregnation, Pd nanoparticles with appropriate particle sizes are uniformly loaded on the surface of pyrochlore. For the reaction of the furanic aldehydes, all of these pyrochlore-based catalysts exhibit hydrogenation and hydrolysis rates that are both faster than those of traditional support-based catalysts due to the oxygen vacancy and pure Lewis acidity of the support. Among these pyrochlore-based catalysts, Pd/Y2Sn2O7 exhibits activity and selectivity that are higher than those of Pd/La2Sn2O7. Moreover, the Y2Sn2O7-based catalyst partially substituted by Ce3+ ions at the B site is more efficient, with the highest cyclopentanone yield and 3-hydroxymethyl cyclopentanone yield of 95.0percent and 92.5percent, respectively. Furthermore, the catalyst can still maintain an effective activity and stability after 4 runs. This study not only presents an efficient biobased route for the production of cyclopentanone compounds but also focuses on the acid catalytic performance of pyrochlore based on its pure Lewis acidity.
- Deng, Qiang,Deng, Shuguang,Gao, Rui,Li, Xiang,Wang, Jun,Zeng, Zheling,Zou, Ji-Jun
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- Self-assembled two-dimensional water-soluble dipicolinate Cu/Na coordination polymer: Structural features and catalytic activity for the mild peroxidative oxidation of cycloalkanes in acid-free medium
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The new water-soluble 2D Cu/Na coordination polymer [Cu(μ-dipic) 2{Na2(μ-H2O)4}] n·2nH2O (1) has been synthesized by self-assembly in aqueous medium from copper(II) nitrate, dipicolinic acid (H2dipic) and sodium hydroxide in the presence of triethanolamine. It has been characterized by IR spectroscopy, FAB+-MS, elemental and single-crystal X-ray diffraction analyses, the latter featuring a layered 2D metal-organic structure that is extended to a 3D supramolecular assembly by extensive hydrogen bonding between adjacent layers and involving crystallization water molecules. Compound 1 has been shown to act as a catalyst precursor for the peroxidative oxidation of cyclohexane and cyclopentane to the corresponding cyclic ketones and alcohols by aqueous H2O2 in MeCN solution and in the absence of acid additives. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Kirillova, Marina V.,Kirillov, Alexander M.,Guedes Da Silva, M. Fatima C.,Pombeiro, Armando J. L.
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- Production of cyclopentanone from furfural over Ru/C with Al11.6PO23.7 and application in the synthesis of diesel range alkanes
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The bio-based platform molecule furfural was converted to the high value chemical cyclopentanone over Ru/C (0.5?wt%) and Al11.6PO23.7 catalysts in good yield (84%) with water as the medium. After screening the reaction conditions, the selectivity for cyclopentanone and cyclopentanol could be controlled by adjusting the hydrogen pressure at the temperature of 433 K. Herein, we propose a new mechanism for the synergistic catalysis of a Bronsted acid and Lewis acid for the conversion of furfural to cyclopentanone through the cyclopentenone route, which is catalyzed by Ru/C and Al11.6PO23.7. In addition, based on cyclopentanone, higher octane number cyclic alkanes (>85% selectivity), which are used as hydrocarbon fuels, were synthesized via a C-C coupling reaction followed by hydrodeoxygenation.
- Shen, Tao,Hu, Ruijia,Zhu, Chenjie,Li, Ming,Zhuang, Wei,Tang, Chenglun,Ying, Hanjie
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- Selective conversion of furfural to cyclopentanone or cyclopentanol using different preparation methods of Cu-Co catalysts
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Cu-Co catalysts, prepared by a co-precipitation method (CP) and an oxalate sol-gel method (OG), can selectively convert furfural (FFA) to cyclopentanone (CPO) or cyclopentanol (CPL), respectively. The conversion of FFA to CPO or CPL by Cu-Co catalysts were studied in aqueous solutions. We found that the product distribution was influenced by the catalyst support, Cu loading, calcination temperature, hydrogen pressure, the number of times the catalyst was reused and the preparation method of the catalyst. The surface morphology, surface area and composition of the catalysts were studied by XRD, XPS, BET, ICP-AES and TEM characterization. We found that there was a strong interaction between Cu and Co. Cu0, Cu2O and Co0 were the main active catalyst phases on the surfaces of the catalysts, but the amounts were different in the different catalysts. Cu0, Co0 and Cu2O were the active hydrogenation species, and Cu2O also played the role of an electrophile or Lewis acid to polarize the CO bond via lone pair electrons on the oxygen atom. According to XRD and XPS, the main phases on the surface of the CP catalysts were Cu0 and Cu2O. The hydrogenation activity of the CP catalyst was relatively weak and the main product was CPO. In contrast, the hydrogenation activity of the OG catalyst was high and the main product was the fully hydrogenated product CPL due to the main active phases of Co0 and Cu2O on the surface of the OG catalyst. At lower hydrogen pressure (2 MPa) and lower Cu loadings (2% for OG, 5% for CP), we obtained the highest yield of 67% CPO and 68% CPL, respectively. This journal is
- Li, Xing-Long,Deng, Jin,Shi, Jing,Pan, Tao,Yu,Xu, Hua-Jian,Fu, Yao
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- Photoinduced reversible structural transformation and selective oxidation catalysis of unsaturated ruthenium complexes supported on SiO2
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(Chemical Equation Presented) Ru experienced? Two novel coordinatively unsaturated SiO2-supported Ru complexes were prepared by photoinduced ligand elimination, accompanied by dissociative coordination of a surface OH group to the unsaturated Ru center by photoirradiation. Wavelength- and atmosphere-dependent photoinduced reversible interconversion occurs between the two Ru complexes. One of the complexes is catalytically active for the photooxidation of cycloalkanes with O2.
- Tada, Mizuki,Akatsuka, Yusaku,Yang, Yong,Sasaki, Takehiko,Kinoshita, Mutsuo,Motokura, Ken,Iwasawa, Yasuhiro
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- An efficient method for the catalytic aerobic oxidation of cycloalkanes using 3,4,5,6-Tetrafluoro-N-Hydroxyphthalimide (F4-NHPI)
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N-Hydroxyphthalimide (NHPI) is known to be an effective catalyst for the oxidation of hydrocarbons. The catalytic activity of NHPI derivatives is generally increased by introducing an electron-withdrawing group on the benzene ring. In a previous report, two NHPI derivatives containing fluorinated alkyl chain were prepared and their catalytic activity was investigated in the oxidation of cycloalkanes. It was found that the fluorinated NHPI derivatives showed better yields for the oxidation reaction. As a continuation of our work with fluorinated NHPI derivatives, our next aim was to investigate the catalytic activity of the NHPI derivatives by introducing fluorine atoms in the benzene ring of NHPI. In the present research, 3,4,5,6-Tetrafluoro-N-Hydroxyphthalimide (F4-NHPI) is prepared and its catalytic activity has been investigated in the oxidation of two different cycloalkanes for the first time. It has been found that F4-NHPI showed higher catalytic efficiency compared with that of the parent NHPI catalyst in the present reactions. The presence of a fluorinated solvent and an additive was also found to accelerate the oxidation.
- Guha, Samar K.,Ishii, Yasutaka
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p. 327 - 335
(2021/12/13)
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- Solvent effect on the rate and direction of furfural transformations during hydrogenation over the Pd/C catalyst
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The rate and directions of transformations during the liquid-phase hydrogenation of furfural with molecular hydrogen in the presence of the 5%Pd/C catalyst (at 423 K, 3 MPa) depend substantially on the chemical nature of the solvent. The main products of
- Belskaya, O. B.,Likholobov, V. A.,Mironenko, R. M.
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- Chemoselective Hydrogenation of Olefins Using a Nanostructured Nickel Catalyst
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The selective hydrogenation of functionalized olefins is of great importance in the chemical and pharmaceutical industry. Here, we report on a nanostructured nickel catalyst that enables the selective hydrogenation of purely aliphatic and functionalized olefins under mild conditions. The earth-abundant metal catalyst allows the selective hydrogenation of sterically protected olefins and further tolerates functional groups such as carbonyls, esters, ethers and nitriles. The characterization of our catalyst revealed the formation of surface oxidized metallic nickel nanoparticles stabilized by a N-doped carbon layer on the active carbon support.
- Klarner, Mara,Bieger, Sandra,Drechsler, Markus,Kempe, Rhett
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supporting information
p. 2157 - 2161
(2021/05/21)
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- Synthesis of Chiral Amines via a Bi-Enzymatic Cascade Using an Ene-Reductase and Amine Dehydrogenase
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Access to chiral amines with more than one stereocentre remains challenging, although an increasing number of methods are emerging. Here we developed a proof-of-concept bi-enzymatic cascade, consisting of an ene reductase and amine dehydrogenase (AmDH), to afford chiral diastereomerically enriched amines in one pot. The asymmetric reduction of unsaturated ketones and aldehydes by ene reductases from the Old Yellow Enzyme family (OYE) was adapted to reaction conditions for the reductive amination by amine dehydrogenases. By studying the substrate profiles of both reported biocatalysts, thirteen unsaturated carbonyl substrates were assayed against the best duo OYE/AmDH. Low (5 %) to high (97 %) conversion rates were obtained with enantiomeric and diastereomeric excess of up to 99 %. We expect our established bi-enzymatic cascade to allow access to chiral amines with both high enantiomeric and diastereomeric excess from varying alkene substrates depending on the combination of enzymes.
- Fossey-Jouenne, Aurélie,Jongkind, Ewald P. J.,Mayol, Ombeline,Paul, Caroline E.,Vergne-Vaxelaire, Carine,Zaparucha, Anne
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- Application of imidazole carbonate in preparation of chemical intermediate
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The invention provides an application of an imidazole carbonate in preparation of a chemical intermediate cyclopentanone, which is characterized by comprising the following steps: placing cyclopentenein a reaction vessel, adding ionic liquid imidazole carbonate and a Wacker catalyst, introducing an oxygen source, stirring and heating to react at normal pressure, and carrying out after-treatment to obtain cyclopentanone. The ionic liquid imidazole carbonate is used as a solvent, the system can fully react without a high-pressure condition, the reaction time is greatly shortened, the high yieldand purity of the product can be ensured, the method is particularly suitable for industrial production, and an unexpected technical effect is achieved.
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Paragraph 0036-0049
(2021/03/13)
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- Green oxidation of amines by a novel cold-adapted monoamine oxidase mao p3 from psychrophilic fungi pseudogymnoascus sp. p3
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The use of monoamine oxidases (MAOs) in amine oxidation is a great example of how biocatalysis can be applied in the agricultural or pharmaceutical industry and manufacturing of fine chemicals to make a shift from traditional chemical synthesis towards more sustainable green chemistry. This article reports the screening of fourteen Antarctic fungi strains for MAO activity and the discovery of a novel psychrozyme MAOP3 isolated from the Pseudogymnoascus sp. P3. The activity of the native enzyme was 1350 ± 10.5 U/L towards a primary (n-butylamine) amine, and 1470 ± 10.6 U/L towards a secondary (6,6-dimethyl-3-azabicyclohexane) amine. MAO P3 has the potential for applications in biotransformations due to its wide substrate specificity (aliphatic and cyclic amines, pyrrolidine derivatives). The psychrozyme operates at an optimal temperature of 30? C, retains 75% of activity at 20? C, and is rather thermolabile, which is beneficial for a reduction in the overall costs of a bioprocess and offers a convenient way of heat inactivation. The reported biocatalyst is the first psychrophilic MAO; its unique biochemical properties, substrate specificity, and effectiveness predispose MAO P3 for use in environmentally friendly, low-emission biotransformations.
- Bia?kowska, Aneta M.,Jod?owska, Iga,Szymczak, Kamil,Twarda-Clapa, Aleksandra
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supporting information
(2021/10/25)
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- Chromium-Catalyzed Production of Diols From Olefins
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Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
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Paragraph 0111
(2021/03/19)
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- Time-Dependent Self-Assembly of Copper(II) Coordination Polymers and Tetranuclear Rings: Catalysts for Oxidative Functionalization of Saturated Hydrocarbons
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This study describes a time-dependent self-assembly generation of new copper(II) coordination compounds from an aqueous-medium reaction mixture composed of copper(II) nitrate, H3bes biobuffer (N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid), ammonium hydroxide, and benzenecarboxylic acid, namely, 4-methoxybenzoic (Hfmba) or 4-chlorobenzoic (Hfcba) acid. Two products were isolated from each reaction, namely, 1D coordination polymers [Cu3(μ3-OH)2(μ-fmba)2(fmba)2(H2O)2]n (1) or [Cu2(μ-OH)2(μ-fcba)2]n (2) and discrete tetracopper(II) rings [Cu4(μ-Hbes)3(μ-H2bes)(μ-fmba)]·2H2O (3) or [Cu4(μ-Hbes)3(μ-H2bes)(μ-fcba)]·4H2O (4), respectively. These four compounds were obtained as microcrystalline air-stable solids and characterized by standard methods, including the single-crystal X-ray diffraction. The structures of 1 and 2 feature distinct types of metal-organic chains driven by the μ3- or μ-OH- ligands along with the μ-benzenecarboxylate linkers. The structures of 3 and 4 disclose the chairlike Cu4 rings assembled from four μ-bridging and chelating aminoalcoholate ligands along with μ-benzenecarboxylate moieties playing a core-stabilizing role. Catalytic activity of 1-4 was investigated in two model reactions, namely, (a) the mild oxidation of saturated hydrocarbons with hydrogen peroxide to form alcohols and ketones and (b) the mild carboxylation of alkanes with carbon monoxide, water, and peroxodisulfate to generate carboxylic acids. Cyclohexane and propane were used as model cyclic and gaseous alkanes, while the substrate scope also included cyclopentane, cycloheptane, and cyclooctane. Different reaction parameters were investigated, including an effect of the acid cocatalyst and various selectivity parameters. The obtained total product yields (up to 34% based on C3H8 or up to 47% based on C6H12) in the carboxylation of propane and cyclohexane are remarkable taking into account an inertness of these saturated hydrocarbons and low reaction temperatures (50-60 °C). Apart from notable catalytic activity, this study showcases a novel time-dependent synthetic strategy for the self-assembly of two different Cu(II) compounds from the same reaction mixture.
- Costa, Ines F. M.,Kirillova, Marina V.,André, Vania,Fernandes, Tiago A.,Kirillov, Alexander M.
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supporting information
p. 14491 - 14503
(2021/07/19)
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- Three metal centers (Co _AOMARKENCODEAMPX0AOA) Cu _AOMARKENCODEAMPX0AOA Method using Zn) 2D MOFs/ultraviolet light to catalyze oxidation of cycloalkane
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The invention relates to a three-metal center (Co _AOMARKENCODEAMPX0AOA). Cu _AOMARKENCODEAMPX0AOA The method comprises Zn) 2D MOFs/ultraviolet light catalytic oxidation of cycloalkane to synthesize cycloalkyl alcohol and cycloalkanone, and belongs to the field of industrial catalysis and fine organic synthesis. To the application method, metalloporphyrin three-metal center (Co _AOMARKENCODEAMPX0AOA) is used. Cu _AOMARKENCODEAMPX0AOA Zn) 2D MOFs dispersed in cycloalkane, wherein metalloporphyrin three-metal center (Co _AOMARKENCODEAMPX0AOA) Cu _AOMARKENCODEAMPX0AOA Zn) 2D MOFs mass is 0.01% - 20%, g / mol of the substance of the cycloalkane, and the reaction system is sealed. An oxidant is introduced, the ultraviolet lamp is a light source, and the reaction liquid of the stirring reaction 2.0-24 . 0h. is subjected to post-treatment to obtain the product cycloalkyl alcohol and cycloalkyl ketone. The method provided by the invention has the advantages of low reaction temperature, mild reaction conditions, high reaction efficiency, high selectivity of cycloalkyl alcohol and cycloalkyl ketone, less byproducts and small environmental impact. The invention provides a high efficiency. Available, safe cycloalkanes selectively catalyze the oxidative synthesis of cycloalkyl alcohols and cycloalkyl ketones.
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Paragraph 0028; 0075-0076
(2021/11/06)
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- Efficient Aliphatic C-H Oxidation and C═C Epoxidation Catalyzed by Porous Organic Polymer-Supported Single-Site Manganese Catalysts
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Bioinspired manganese complexes have emerged over recent decades as attractive catalysts for a number of selective oxidation reactions. However, these catalysts still suffer from oxidative degradation. In the present study, we prepared a series of porous Mn-N4 catalysts in which the catalytic units are embedded in the skeleton of porous organic polymers (POPs). These POP-based manganese catalysts demonstrated high reactivity in the oxidation of aliphatic C-H bonds and the asymmetric epoxidation of olefins. Furthermore, these catalysts could be readily recycled and reused due to their heterogeneous nature. Morphological characterization revealed that the Mn-N4 complex was individually distributed over a porous polymer network. Remarkably, the nature of the single-site catalyst prevented oxidative degradation during the reaction. The present work has thus developed a successful approach for bioinspired single-site manganese catalysts in which the oxidation reaction is confined to a specific channel in an enzyme-like mode.
- Wang, Bingyang,Lin, Jin,Sun, Qiangsheng,Xia, Chungu,Sun, Wei
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p. 10964 - 10973
(2021/09/08)
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- SBA-15 Supported Silver Catalyst for the Efficient Aerobic Oxidation of Toluene Under Solvent-Free Conditions
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The efficient SBA-15 supported silver catalysts(Ag/SBA-15) were prepared and characterized by ICP-OES, XRD, TEM, SEM, XPS and N2 adsorption–desorption techniques. The catalysts exhibited an excellent catalytic activity for the aerobic oxidation of toluene to benzaldehyde under solvent-free conditions. Conversion of toluene and selectivity of benzaldehyde were 50% and 89% respectively over catalyst with 9.1 wt% Ag loading (10Ag/SBA-15). A wide range of substrates were tolerated under the selected reaction conditions. The kinetic study shows that the oxidation of toluene over 10Ag/SBA-15 is pseudo-first-order reaction and the activation energy Ea is 45.1?kJ/mol. A plausible mechanism involving oxygen free radicals was proposed for the aerobic oxidation reaction. Compared with the traditional method, the newly designed heterogeneous catalytic system shows better economic applicability, environmental friendliness and broader application prospects. Graphical abstract: [Figure not available: see fulltext.]
- Chen, Lei,Chen, Yanjiao,Dai, Xuan,Guo, Jiaming,Peng, Xinhua
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- Visible-light photocatalytic selective oxidation of C(sp3)-H bonds by anion-cation dual-metal-site nanoscale localized carbon nitride
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Selective oxidation of C(sp3)-H bonds to carbonyl groups by abstracting H with a photoinduced highly active oxygen radical is an effective method used to give high value products. Here, we report a heterogeneous photocatalytic alkanes C-H bonds oxidation method under the irradiation of visible light (λ= 425 nm) at ambient temperature using an anion-cation dual-metal-site modulated carbon nitride. The optimized cation (C) of Fe3+or Ni2+, with an anion (A) of phosphotungstate (PW123?) constitutes the nanoscale dual-metal-site (DMS). With a Fe-PW12dual-metal-site as a model (FePW), we demonstrate a A-C DMS nanoscale localized carbon nitride (A-C/g-C3N4) exhibiting a highly enhanced photocatalytic activity with a high product yield (86% conversion), selectivity (up to 99%), and a wide functional group tolerance (52 examples). The carbon nitride performs the roles of both the visible light response, and improves the selectivity for the oxidation of C(sp3)-H bonds to carbonyl groups, along with the function of A-C DMS in promoting product yield. Mechanistic studies indicate that this reaction follows a radical pathway catalyzed by a photogenerated electron and hole on A-C/g-C3N4that is mediated by thetBuO˙ andtBuOO˙ radicals. Notably, a 10 g scale reaction was successfully achieved for alkane photocatalytic oxidation to the corresponding product with a good yield (80% conversion), and high selectivity (95%) under natural sunlight at ambient temperature. In addition, this A-C/g-C3N4photocatalyst is highly robust and can be reused at least six times and the activity is maintained.
- Duan, Limei,Li, Peihe,Li, Wanfei,Liu, Jinghai,Liu, Ying,Liu, Zhifei,Lu, Ye,Sarina, Sarina,Wang, Jinghui,Wang, Yin,Wang, Yingying,Zhu, Huaiyong
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p. 4429 - 4438
(2021/07/12)
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- Nature of polymeric condensates during furfural rearrangement to cyclopentanone and cyclopentanol over Cu-based catalysts
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Catalyst deactivation and carbon loss are frequently encountered problems in furfural conversion in the aqueous phase. Although several mechanisms were proposed, an in-depth experimental study on the spent catalysts and condensates formed on catalyst surfaces is essential for the development of catalysts with high resistance to condensation. A series of Cu catalysts with various alkali or alkaline earth metal additives was synthesized and tested for furfural conversion to cyclopentanone and cyclopentanol. The addition of alkali or alkaline earth metals significantly inhibited the condensate formation, likely due to the stabilization effect of the important carbocation intermediate. Characterization techniques including FT-IR, XRD, thermogravimetric analysis, and pyrolysis GC-MS were used to analyze the spent catalysts. The results revealed that the condensates formed on the catalyst surface were highly conjugated polymers resulting from the polymerization of furfuryl alcohol. The conclusions of this research are applicable to other furfural hydroconversions in the aqueous phase in acidic or neutral environments. This journal is
- Cai, Xichen,Li, Cuiqing,Li, Dongsheng,Li, Zhanqiao,Song, Yongji,Tian, Ziyou,Wang, Hong,Zhang, Chen,Zhang, Wei
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p. 22767 - 22777
(2021/12/24)
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- Nitrogen-Doped Carbon Composites with Ordered Macropores and Hollow Walls
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Metal-organic frameworks provide versatile templates for the fabrication of various metal/carbon materials, but most of the derived composites possess only microspores, limiting the accessibility of embedded active sites. Herein, we report the construction of cobalt/nitrogen-doped carbon composites with a three-dimensional (3D) ordered macroporous and hollow-wall structure (H-3DOM-Co/NC) using a single-crystal ordered macropore (SOM)-ZIF-8@ZIF-67 as precursor. During the pyrolysis, the interconnected macroporous structure of SOM-ZIF-8@ZIF-67 is mostly preserved, whereas the pore wall achieves a solid-to-hollow transformation with Co nanoparticles formed in the hollow walls. The 3D-ordered macroporous carbon skeleton may effectively promote long-range mass transfer and the hollow wall can facilitate local accessibility of active sites. This unique structure can greatly boost its catalytic activity in the selective hydrogenation of biomass-derived furfural to cyclopentanol, much superior to its counterparts without this well-designed hierarchically porous structure.
- Chen, Jianmin,Chen, Liyu,Fang, Ruiqi,Li, Yingwei,Qin, Ze,Wang, Yajing,Yang, Xianfeng,Yao, Wen
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supporting information
p. 23729 - 23734
(2021/10/04)
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- Selective tandem hydrogenation and rearrangement of furfural to cyclopentanone over CuNi bimetallic catalyst in water
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Tandem catalysis for the hydrogenation rearrangement of furfural (FA) provides an attractive solution for manufacturing cyclopentanone (CPO) from renewable biomass resources. The CuNi/Al-MCM-41 catalyst was synthesized and afforded excellent catalytic performance with 99.0% conversion and 97.7% selectivity to CPO in a near-neutral solution under 2.0 MPa H2 at 160 °C for 5 h, much higher than those on other molecular sieve supports including MCM-41, SBA-15, HY, and ZSM-5. A small amount of Al highly dispersed in MCM-41 plays an anchoring role and ensures the formation of highly dispersed CuNi bimetallic nanoparticles (NPs). The remarkably improved catalytic performance may be attributed to the bimetallic synergistic and charge transfer effects. In addition, the initial FA concentration and the aqueous system pH required precise control to minimize polymerization and achieve high selectivity of CPO. Fourier transform infrared spectroscopy and mass spectra results indicated that polymerization was sensitive to pH values. Under acidic conditions, FA and intermediate furfuryl alcohol polymerize, while the intermediate 4-hydroxy-2-cyclopentenone mainly polymerizes under alkaline conditions, blocking the cascade of multiple reactions. Therefore, near-neutral conditions are most suitable for minimizing the impact of polymerization. This study provides a useful solution for the current universal problems of polymerization side reactions and low carbon balance for biomass conversion.
- Gao, Jin,Liu, Xin,Luo, Yang,Ma, Hong,Sun, Yuxia,Xu, Jie,Zhang, Meiyun,Zhang, Shujing
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p. 2216 - 2224
(2021/09/20)
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- Method for preparing cyclopentanone compound by aqueous phase hydrogenation rearrangement of furfural and derivative thereof
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The invention provides a method for preparing a cyclopentanone compound by aqueous phase hydrogenation rearrangement of furfural and a derivative thereof, and belongs to the field of catalytic conversion of biomass resources. Specifically, a supported Ni3P catalyst converts furfural and a derivative thereof into a cyclopentanone compound in an H2 atmosphere, wherein the supported Ni3P catalyst provided by the invention is prepared by a deposition-precipitation chemical plating method. According to the invention, the catalyst obtained by the method is high in dispersity and small in particle size, and has high furfural and derivative conversion rate and cyclopentanone compound selectivity in the reaction of preparing cyclopentanone and derivatives thereof by aqueous phase hydrogenation rearrangement of furfural and derivatives thereof; and the furfural conversion rate and the cyclopentanone selectivity respectively reach 89.1% and 81.3% after the reaction is carried out for 1 hour at the pressure of 4 MPa H2 and the temperature of 160 DEG C.
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Paragraph 0024-0047; 0057-0059
(2021/01/20)
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- Highly Controllable Hydrogenative Ring Rearrangement and Complete Hydrogenation Of Biobased Furfurals over Pd/La2B2O7 (B=Ti, Zr, Ce)
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Developing a highly selective catalyst to upgrade furfurals (5-hydroxymethyl furfural and furfural) to cyclopentanones (3-hydroxymethyl cyclopentanone and cyclopentanone) and tetrahydrofuran alcohols (2,5-bishydroxymethyl tetrahydrofuran and tetrahydrofuran alcohol) is highly significant for biobased fine chemical synthesis. Here, a series of La2B2O7 (B=Ti, Zr, Ce) metal oxides, featuring the same chemical formula but different topological structures are fabricated. After Pd loading, the Lewis acidity and metal-support interaction are well governed by the support type, which further affects the hydrogenation and acid-catalyzed ability. A greater than 82 % yield of cyclopentanones is obtained via a hydrogenative ring rearrangement route over Pd/La2Ti2O7. However, Pd/La2Ce2O7 shows high catalytic efficiency for tetrahydrofuran alcohols with an approximately 80 % yield via a complete hydrogenation route. Additionally, the catalyst exhibits outstanding recycling performance and structural stability. This study presents an interesting design strategy for the selective preparation of cyclopentanones and tetrahydrofuran alcohols through the regulation of the adsorption mechanism.
- Tong, Zhikun,Gao, Rui,Li, Xiang,Guo, Lingyun,Wang, Jun,Zeng, Zheling,Deng, Qiang,Deng, Shuguang
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p. 4549 - 4556
(2021/09/09)
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- Hydrogenative ring-rearrangement of furfural to cyclopentanone over pd/uio-66-no2 with tunable missing-linker defects
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Upgrading furfural (FAL) to cyclopentanone (CPO) is of great importance for the synthesis of high-value chemicals and biomass utilization. The hydrogenative ring-rearrangement of FAL is catalyzed by metal-acid bifunctional catalysts. The Lewis acidity is a key factor in promoting the rearrangement of furan rings and achieving a high selectivity to CPO. In this work, highly dispersed Pd nanoparticles were successfully encapsulated into the cavities of a Zr based MOF, UiO-66-NO2, by impregnation using a double-solvent method (DSM) followed by H2 reduction. The obtained Pd/UiO-66-NO2 catalyst showed a significantly better catalytic performance in the aforementioned reaction than the Pd/UiO-66 catalyst due to the higher Lewis acidity of the support. Moreover, by using a thermal treatment. The Lewis acidity can be further increased through the creating of missing-linker defects. The resulting defective Pd/UiO-66-NO2 exhibited the highest CPO selectivity and FAL conversion of 96.6% and 98.9%, respectively. In addition, the catalyst was able to maintain a high activity and stability after four consecutive runs. The current study not only provides an efficient catalytic reaction system for the hydrogenative ring-rearrangement of furfural to cyclopentanone but also emphasizes the importance of defect sites.
- Leus, Karen,Liu, Ying-Ya,Shi, Chuan,Sun, Zhichao,Van Der Voort, Pascal,Wang, Anjie,Wang, Chunhua,Wang, Yao,Yang, Yuhao,Yu, Zhiquan
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- Efficient oxidation of cycloalkanes with simultaneously increased conversion and selectivity using O2 catalyzed by metalloporphyrins and boosted by Zn(AcO)2: A practical strategy to inhibit the formation of aliphatic diacids
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The direct sources of aliphatic acids in cycloalkanes oxidation were investigated, and a strategy to suppress the formation of aliphatic acids was adopted through enhancing the catalytic transformation of oxidation intermediates cycloalkyl hydroperoxides to cycloalkanols by Zn(II) and delaying the emergence of cycloalkanones. Benefitted from the delayed formation of cycloalkanones and suppressed non-selective thermal decomposition of cycloalkyl hydroperoxides, the conversion of cycloalkanes and selectivity towards cycloalkanols and cycloalkanones were increased simultaneously with satisfying tolerance to both of metalloporphyrins and substrates. For cyclohexane, the selectivity towards KA-oil was increased from 80.1% to 96.9% meanwhile the conversion was increased from 3.83 % to 6.53 %, a very competitive conversion level with higher selectivity compared with current industrial process. This protocol is not only a valuable strategy to overcome the problems of low conversion and low selectivity lying in front of current cyclohexane oxidation in industry, but also an important reference to other alkanes oxidation.
- Shen, Hai-Min,Wang, Xiong,Ning, Lei,Guo, A-Bing,Deng, Jin-Hui,She, Yuan-Bin
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- Selective aqueous-phase hydrogenation of furfural to cyclopentanol over Ni-based catalysts prepared from Ni-MOF composite
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Metal-organic frameworks (MOFs) as an emerging class of porous materials exhibit some unique advantages, including controllable composition, a large surface area, high porosity, and so on. In this work, the spherical NiMo bimetal catalysts supported on porous carbon matrix were prepared using a simple wet impregnation method and studied for selective hydrogenation of furfural (FFA). Three different catalysts were investigated including Ni/C-Mo-BTC, Ni/C-Mo-DHTA and Ni/C-Mo-PTA. Of the catalysts studied the Ni/C-Mo-BTC catalyst could achieve the highest selectivity of CPL (up to 90%) under moderate reaction conditions (140 °C, 2 MPa, 2 h) in aqueous medium. In addition, other Ni-based catalysts (Ni/C-Fe, Ni/C-Zn, Ni/C-Cu, Ni/C-Ce) were also investigated to achieve yields of 20–70% under the same reaction conditions. The influence of temperature, H2 pressure, time and solvent were investigated for the best performing catalyst. Based on the optimal reaction condition, various of furfural derivatives could also be effectively transferred to produce corresponding products. The detailed physicochemical characterization was carried out by means of XRD, SEM, TEM, XPS, NH3-TPD and Raman analysis. In the end, the optimal Ni/C-Mo0.4 catalyst could be recycled magnetically and efficiently applied in the next run for five consecutive recycling tests in the FFA hydrogenation to CPL. The results suggested Ni/C-Mo0.4 catalyst occurred to increasingly favor the formation of Ni-Mo alloys and suggested a metallic active site in FFA hydrogenation with the addition of element Mo. Mechanism study indicated that water was a key factor contributing to the formation of different desired products, which was responsible for the arrangement of furan compound.
- Chen, Changzhou,Jiang, Jianchun,Li, Jing,Ren, Jurong,Wu, Dichao,Xia, Haihong,Zhou, Minghao
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- Heterogeneous Cobalt-Catalyzed C?C Bond Cleavage in Alcohols to Carbonyl Compounds
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Cobalt oxide hydrate (Co(OH)x) supported on metal oxides were prepared. The oxidative cleavage of C(OH)?C bond in alcohol was catalyzed by Co(OH)x/metal oxides using molecular oxygen as the oxidant, and the corresponding product was obtained with high selectivity. The composition and characteristics of the catalysts were analyzed by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), high-angle ring dark-field scanning TEM (HAADF-STEM), N2 physico-adsorption characterization, inductively coupled plasma optical emission spectrometry (ICP-OES), Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectroscopy (XPS) and NH3-temperature-programmed desorption (NH3-TPD). Additionally, a reasonable reaction mechanism was proposed based on the characterization results and a series of controlled experiments. Notably, this heterogeneous catalytic system did not require any additives and had good recycling performance.
- Teng, Jia-nan,Zhu, Rui,Li, Xinglong,Fu, Yao
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p. 4355 - 4363
(2021/09/14)
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- Selective Aerobic Oxidation of Secondary C (sp3)-H Bonds with NHPI/CAN Catalytic System
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Abstract: The direct aerobic oxidation of secondarty C(sp3)-H bonds was achieved in the presence of N-hydroxyphthalimide (NHPI) and cerium ammonium nitrate (CAN) under mild conditions. Various benzylic methylenes could be oxidized to carbonyl compounds in satisfied selectivity while saturated cyclic alkanes could be further oxidized to the corresponding lactones with the catalytic system. Remarkably, 25% of isochroman was converted to corresponding ketone with a selectivity of 96%. The reaction was initiated by hydrogen atom abstraction from NHPI by cerium and nitrates under oxygen atmosphere to form PINO radicals. 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) addition experiments showed that the oxidation proceeded via a complex radical chain mechanism and an ion pathway. Graphic Abstract: [Figure not available: see fulltext.]
- Wang, Lingyao,Zhang, Yuanbin,Yuan, Haoran,Du, Renfeng,Yao, Jia,Li, Haoran
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p. 1663 - 1669
(2020/10/21)
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- Fine-Bubble-Slug-Flow Hydrogenation of Multiple Bonds and Phenols
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We describe a promising method for the continuous hydrogenation of alkenes or alkynes by using a newly developed fine-bubble generator. The fine-bubble-containing slug-flow system was up to 1.4 times more efficient than a conventional slug-flow method. When applied in the hydrogenation of phenols to the corresponding cyclohexanones, the fine bubble-slug-flow method suppressed over-reduction. As this method does not require the use of excess gas, it is expected to be widely applicable in improving the efficiency of gas-mediated flow reactions.
- Iio, Takuya,Nagai, Kohei,Kozuka, Tomoki,Sammi, Akhtar Mst,Sato, Kohei,Narumi, Tetsuo,Mase, Nobuyuki
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supporting information
p. 1919 - 1924
(2020/11/09)
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- Regioselective Wacker-Type Oxidation of Internal Olefins in tBuOH Using Oxygen as the Sole Oxidant and tBuONO as the Organic Redox Cocatalyst
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A regioselective Wacker-Tsuji oxidation of internal olefins in tBuOH has been developed using oxygen as the terminal oxidant and tert-butyl nitrite as the simple organic redox cocatalyst without the involvement of hazardous cocatalysts or harsh reaction conditions. A series of internal olefins bearing various functional groups can be oxidized to the corresponding substituted ketones in generally good yields with high regioselectivities.
- Huang, Qing,Li, Ya-Wei,Ning, Xiao-Shan,Jiang, Guo-Qing,Zhang, Xiao-Wei,Qu, Jian-Ping,Kang, Yan-Biao
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supporting information
p. 965 - 969
(2020/02/15)
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- Catalytic Oxidative Deamination by Water with H2Liberation
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Selective oxidative deamination has long been considered to be an important but challenging transformation, although it is a common critical process in the metabolism of bioactive amino compounds. Most of the synthetic methods developed so far rely on the use of stoichiometric amounts of strong and toxic oxidants. Here we present a green and efficient method for oxidative deamination, using water as the oxidant, catalyzed by a ruthenium pincer complex. This unprecedented reaction protocol liberates hydrogen gas and avoids the use of sacrificial oxidants. A wide variety of primary amines are selectively transformed to carboxylates or ketones in good to high yields. It is noteworthy that mechanistic experiments and DFT calculations indicate that in addition to serving as the oxidant, water also plays an important role in assisting the hydrogen liberation steps involved in amine dehydrogenation.
- Tang, Shan,Rauch, Michael,Montag, Michael,Diskin-Posner, Yael,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 20875 - 20882
(2020/12/23)
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- Supramolecular bimetallic vanadium(V) complex driven by hydrogen bonding and O???O chalcogen bonding interaction: Oxidation of cyclohexane and its application toward C[sbnd]H bond activation
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Vanadium(V) complex was synthesized in good yield and characterized by FT-IR, UV–Visible and NMR spectroscopy. The structure of the complex was confirmed by single X-ray crystallography. X-ray structural analysis the complex featuring O???O chalcogen bonding interaction and other short interaction. The O???O intermolecular interactions distance is 2.794 ?. Clearly, the O???O intermolecular distance in the O-linked complex is less than the sum of van der Waals atomic radii of oxygen 3.00 ? (rvdW (O) = 1.50 ?). Oxidations of cyclohexane to cyclohexanol were also carried out, using the synthetic complex as a catalyst. The catalytic studies were carried out successfully using m-chloroperbenzoic acid as oxidant at 100 °C, under solvents free conditions. The catalytic protocols are very simple and the catalyst can be recovered without any lost in products formation in the next consecutive cycle.
- Clovis, Ndege Simisi,Kurbah, Sunshine Dominic
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- Method for catalyzing liquid-phase selective oxidation of aromatic hydrocarbon and cycloalkane
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The invention provides a method for catalyzing liquid-phase selective oxidation of aromatic hydrocarbon and cycloalkane. The method comprises the following steps of: dispersing a raw material, a radical initiator and a catalyst in a solvent, and carrying out reaction at 60-90DEG C under a reaction pressure of 0.5-2MPa for 5-12h by using oxygen as an oxidant; wherein the raw material is aromatic hydrocarbon or cycloalkane; the catalyst is a binuclear copper porphyrin compound with a structure shown as a general formula (I), wherein M is Cu, and R is selected from halogen; the dosage of the catalyst is 0.003-0.005% of the molar weight of the raw material, and the dosage of the radical initiator is 2-5% of the molar weight of the raw material. According to the method, binuclear metalloporphyrin is used as a catalyst, oxygen is used as an oxidant to directly catalyze selective oxidation of cycloalkane and aromatic hydrocarbon in one step on the premise of not needing an assistant, the reaction conditions are mild (60-90DEG C and 0.5-2MPa), and the dosage of the catalyst is small.
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Paragraph 0027-0031; 0037-0038
(2020/12/30)
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- A gradient reduction strategy to produce defects-rich nano-twin Cu particles for targeting activation of carbon-carbon or carbon-oxygen in furfural conversion
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Complexity of chemical linkages (C-C/C-H/C-O, C=C/C=O, or C-O-H/C-O-C) in biomass-derived molecules makes the selective activation of targeted bonds much more challenging, expecting well-defined catalysts and definite catalytically-active sites. This work demonstrates an effective gradient reduction strategy to control the definite structure of catalytically-active sites, affording defects-rich nano-twin Cu particles. This strategy just involves the reduction (calcination under H2) of CuII-containing layered double hydroxides (LDHs) simply with controlling the reduction gradient (interval time) of CuII species in two chemical micro-environments (CuII-O-CuII and CuII-O-MII/III/IV (M ≠ Cu)) in the brucite-like layer of LDHs. The nano-twin Cu particles efficiently promote the target activation of C-O and C=C in the conversion of furfural to cyclopentanone (CPO). With ~100% furfural conversion, the defects-rich nano-twin Cu particles afford a CPO selectivity of 92%, 50% higher than regular spherical Cu particles. The multi-stepped defect sites, originating from the planar defects, play a decisive role in promoting the CPO selectivity by facilitating the hydro-deoxygenation to C-O of 4-hydroxycyclopentenone (HCP) and hydrogenation to C=C of HCP or cyclopentenone.
- An, Zhe,Guo, Shaowei,He, Jing,Ma, Xiaodan,Shu, Xin,Song, Hongyan,Xiang, Xu,Zhang, Jian,Zhu, Yanru
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- Reductive Electrochemical Activation of Molecular Oxygen Catalyzed by an Iron-Tungstate Oxide Capsule: Reactivity Studies Consistent with Compound i Type Oxidants
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The reductive activation of molecular oxygen catalyzed by iron-based enzymes toward its use as an oxygen donor is paradigmatic for oxygen transfer reactions in nature. Mechanistic studies on these enzymes and related biomimetic coordination compounds designed to form reactive intermediates, almost invariably using various "shunt" pathways, have shown that high-valent Fe(V)=O and the formally isoelectronic Fe(IV) =O porphyrin cation radical intermediates are often thought to be the active species in alkane and arene hydroxylation and alkene epoxidation reactions. Although this four decade long research effort has yielded a massive amount of spectroscopic data, reactivity studies, and a detailed, but still incomplete, mechanistic understanding, the actual reductive activation of molecular oxygen coupled with efficient catalytic transformations has rarely been experimentally studied. Recently, we found that a completely inorganic iron-tungsten oxide capsule with a keplerate structure, noted as {Fe30W72}, is an effective electrocatalyst for the cathodic activation of molecular oxygen in water leading to the oxidation of light alkanes and alkenes. The present report deals with extensive reactivity studies of these {Fe30W72} electrocatalytic reactions showing (1) arene hydroxylation including kinetic isotope effects and migration of the ipso substituent to the adjacent carbon atom ("NIH shift"); (2) a high kinetic isotope effect for alkyl C - H bond activation; (3) dealkylation of alkylamines and alkylsulfides; (4) desaturation reactions; (5) retention of stereochemistry in cis-alkene epoxidation; and (6) unusual regioselectivity in the oxidation of cyclic and acyclic ketones, alcohols, and carboxylic acids where reactivity is not correlated to the bond disassociation energy; the regioselectivity obtained is attributable to polar effects and/or entropic contributions. Collectively these results also support the conclusion that the active intermediate species formed in the catalytic cycle is consistent with a compound I type oxidant. The activity of {Fe30W72} in cathodic aerobic oxidation reactions shows it to be an inorganic functional analogue of iron-based monooxygenases.
- Bugnola, Marco,Shen, Kaiji,Haviv, Eynat,Neumann, Ronny
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p. 4227 - 4237
(2020/05/05)
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- Metal-free Photocatalytic Aerobic Oxidative Cleavage of C?C Bonds in 1,2-Diols
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The preparation of carbonyl compounds by the aerobic oxidative cleavage of C?C bonds in 1,2-diols under mild reaction conditions is a very significant reaction and is widely employed in various scenarios. Avoiding the use of harmful stoichiometric oxidants and adopting a greener chemical process remain a challenge for this reaction to date. In this manuscript, a heterogeneous metal-free photocatalytic strategy without any additive was developed for aerobic oxidative cleavage of C?C bonds in 1,2-diols at ambient conditions with visible light. The reaction mechanism was further studied through a series of control experiments and density functional theory (DFT) calculations. In addition, the catalytic system showed a broad substrates scope, including aliphatic (linear or cyclic) 1,2-diols, benzylic, alkenyl 1,2-diols, and α-hydroxy acids (such as lactic acid). Thus, this strategy could serve as a method for the transformation of 1,2-diols to corresponding carbonyl compounds by the aerobic oxidative cleavage of C?C bonds.
- Zhu, Rui,Zhou, Gongyu,Teng, Jia-nan,Li, Xinglong,Fu, Yao
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p. 5248 - 5255
(2020/08/21)
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- Highly dispersed Pd catalysts supported on various carbons for furfural hydrogenation
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Furfural (FAL), one of the important platform molecules derived from lignocellulosic biomass, can be converted into valuable chemicals such as furfuryl alcohol or cyclopentanone via hydrogenation. While carbon materials have been used as versatile catalyst supports for FAL hydrogenation, systematic studies on the structure of the catalytic performances are lacking. In this work, we prepare various types of carbon supports to investigate the impact of carbon structures for Pd-catalyzed FAL hydrogenation. Mesoporous carbons, including CMK-3, CMK-5, CMK-8, and MSU-F-C, as well as carbon nanotube and Vulcan XC are used as carbon supports. For the preparation of highly dispersed Pd-supported carbon (Pd/C) catalysts, chemical reduction by sodium borohydride is applied, in which trisodium citrate plays a critical role in anchoring small Pd clusters on the carbons. In the liquid-phase hydrogenation of FAL, CMK-5 with the largest surface area and hexagonal hollow tubular framework is proven to be the most efficient carbon support for Pd/C catalysts, with the highest conversion of FAL in both 2-propanol (100percent) and water (86.4percent) solvents. It is also demonstrated that the product selectivity in FAL hydrogenation over various Pd/C catalysts is changed dramatically depending on the type of solvent. The Pd/C catalysts exhibit similar fractions of product distributions containing furfuryl alcohol, cyclopentanol, tetrahydrofurfuryl alcohol, and minor products in 2-propanol. However, the production of cyclopentanone is increased when water is used as a solvent.
- Lee, Jihyeon,Woo, Jinwoo,Nguyen-Huy, Chinh,Lee, Man Sig,Joo, Sang Hoon,An, Kwangjin
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- Method for catalytic oxidation of cycloalkane by confinement porphyrin Co (II)
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The invention relates to a method for catalytic oxidation of cycloalkane by confinement porphyrin Co (II). The method comprises the following steps: dispersing confinement cobalt porphyrin (II) in cycloalkane, sealing the reaction system, heating to 100-130 DEG C while stirring, introducing oxygen to 0.2-3.0 MPa, keeping the set temperature and oxygen pressure, stirring to react for 3.0-24.0 h, and carrying out post-treatment on a reaction solution to obtain products naphthenic alcohol and naphthenic ketone. The method achieves high selectivity of naphthenic alcohol and naphthenic ketone, andeffectively inhibits the generation of aliphatic diacid. The aliphatic diacid is low in selectivity, so that the continuity of the cycloalkane oxidation process and the separation of the products arefacilitated; the method has the potential of solving the problem that naphthenic alcohol and naphthenic ketone are easily and deeply oxidized to generate aliphatic diacid in the industrial cycloalkanecatalytic oxidation process; and the method is a novel efficient and feasible method for selective catalytic oxidation of cycloalkane.
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Paragraph 0067; 0068
(2020/05/01)
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- Confinement porphyrin Co (II), and preparation method and application thereof
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Confinement porphyrin Co (II). A preparation method includes: under acidic condition, performing condensation on aromatic aldehyde and pyrrole in equal molar ratio to obtain a phenylporphyrin compound, and carrying out metallization in a chloroform-methanol solution to obtain porphyrin Cu (II), performing bromination and demetalization by perchloric acid to obtain confinement porphyrin, performingstirring reflux on the confinement porphyrin in a methanol solution for 12.0-24.0 h to obtain confinement porphyrin Co (II). An application includes: dissolving the confinement porphyrin Co (II) in naphthenic hydrocarbon and sealing the reaction system, stirring and heating the reaction system to 100-130 DEG C and feeding oxygen to 0.2-3.0 MPa; maintaining the set temperature and oxygen pressureand performing a stirring reaction for 3.0-24.0 h; performing after treatment on the reaction liquid to prepare the product. In the invention, generation of fatty diacid is effectively inhibited, andcontinuity of a naphthenic hydrocarbon oxidization process and product separation is facilitated. The invention has the potential of solving the problem that naphthene alcohols and naphthene ketones are liable to undergo deep oxidization and form the fatty diacid in an industrial naphthenic hydrocarbon catalytic oxidation process.
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Paragraph 0099-0100
(2020/04/17)
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- Method for synergistically catalyzing and oxidizing cycloparaffin through confined metalloporphyrin cobalt (II)/Cu (II) salt
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The invention discloses a method for synergistically catalyzing and oxidizing cycloparaffin through confined metalloporphyrin cobalt (II)/Cu (II) salt. The preparation method comprises the following steps: dispersing confined metalloporphyrin cobalt (II) (0.001%-5%, g/mol) and Cu (II) salt (0.01%-10%, mol/mol) into cycloparaffin; and sealing the reaction system, heating the temperature to 90-150 DEG C while stirring, introducing an oxidant, keeping the set temperature and pressure, carrying out stirring and reacting for 2.0-24.0 hours, and carrying out after-treatment on the reaction solutionto obtain the products cycloalkyl alcohol and cycloalkyl ketone. The method disclosed by the invention has the advantages of high cycloalkyl alcohol and cycloalkyl ketone selectivity, low reaction temperature, few byproducts, small environmental influence and the like. In addition, the content of cycloalkyl hydroperoxide is low, and the safety coefficient is high. The invention provides an efficient, feasible and safe method for synthesizing cycloalkyl alcohol and cycloalkyl ketone through selective catalytic oxidation of cycloparaffin.
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Paragraph 0041-0042
(2020/12/10)
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- H2-free Synthesis of Aromatic, Cyclic and Linear Oxygenates from CO2
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The synthesis of oxygenate products, including cyclic ketones and phenol, from carbon dioxide and water in the absence of gas-phase hydrogen has been demonstrated. The reaction takes place in subcritical conditions at 300 °C and pressure at room temperature of 25 barg. This is the first observation of the production of cyclic ketones by this route and represents a step towards the synthesis of valuable intermediates and products, including methanol, without relying on fossil sources or hydrogen, which carries a high carbon footprint in its production by conventional methods. Inspiration for these studies was taken directly from natural processes occurring in hydrothermal environments around ocean vents. Bulk iron and iron oxides were investigated to provide a benchmark for further studies, whereas reactions over alumina and zeolite-based catalysts were employed to demonstrate, for the first time, the ability to use catalyst properties such as acidity and pore size to direct the reaction towards specific products. Bulk iron and iron oxides produced methanol as the major product in concentrations of approximately 2–3 mmol L?1. By limiting the hydrogen availability through increasing the initial CO2/H2O ratio the reaction could be directed to yield phenol. Alumina and zeolites were both observed to enhance the production of longer-chained species (up to C8), likely owing to the role of acid sites in catalysing rapid oligomerisation reactions. Notably, zeolite-based catalysts promoted the formation of cyclic ketones. These proof-of-concept studies show the potential of this process to contribute to sustainable development through either targeting methanol production as part of a “methanol economy” or longer-chained species including phenol and cyclic ketones.
- Gomez, Laura Quintana,Shehab, Amal K.,Al-Shathr, Ali,Ingram, William,Konstantinova, Mariia,Cumming, Denis,McGregor, James
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p. 647 - 658
(2020/01/24)
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- Site-specific catalytic activities to facilitate solvent-free aerobic oxidation of cyclohexylamine to cyclohexanone oxime over highly efficient Nb-modified SBA-15 catalysts
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The development of highly active and selective heterogeneous catalysts for efficient oxidation of cyclohexylamine to cyclohexanone oxime is a challenge associated with the highly sensitive nitrogen center of cyclohexylamine. In this work, dispersed Nb oxide supported on SBA-15 catalysts are disclosed to efficiently catalyze the selective oxidation of cyclohexylamine with high conversion (>75%) and selectivity (>84%) to cyclohexanone oxime by O2without any addition of solvent (TOF = 469.8 h?1, based on the molar amount of Nb sites). The role of the active-site structure identity in dictating the site-specific catalytic activities is probed with the help of different reaction and control conditions and multiple spectroscopy methods. Complementary to the experimental results, further poisoning tests (with KSCN or dehydroxylation reagents) and DFT computational studies clearly unveil that the surface exposed active centers toward activation of the reactants are quite different: the surface -OH groups can catch the NH2group from cyclohexylamine by forming a hydrogen bond and lead to a more facile cyclohexylamine oxidation to desired products, while the monomeric or oligomeric Nb sites with a highly distorted structure play a key role in the dissociation of O2molecules beneficial for insertion of active oxygen species into cyclohexylamine. These catalysts exhibit not only satisfactory recyclability for cyclohexylamine oxidation but also efficiently catalyze the aerobic oxidation of a wide range of amines under solvent-free conditions.
- Ding, Wei,Mao, Liqiu,Peng, Haoyu,Yin, Dulin,Zhong, Wenzhou
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p. 3409 - 3422
(2020/06/09)
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- Effect of pretreatment conditions on acidity and dehydration activity of CeO2-MeOx catalysts
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A series of MeOx-modified CeO2 (CeO2-MnOx, CeO2-ZnO, CeO2-MgO, CeO2-CaO, and CeO2-Na2O) catalysts were prepared by the impregnation of CeO2 with corresponding metal nitrates. Acidity and oxidation state of cerium were investigated on both oxidized and reduced catalysts by employing Fourier Transform Infrared spectroscopy (FTIR) on adsorbed pyridine and in situ H2-Temperature Programmed Reduction/X-ray Absorption Spectroscopy (H2-TPR/XAS) techniques, respectively. Metal oxide addition tended to alter both type and number of acid sites on ceria. EXAFS data showed a significant difference in NCe-O between unmodified and CeO2-MeOx, suggesting that added MeOx interferes with vacancy formation on ceria during reduction. In comparison with air-pretreated samples, H2-pretreated ones under similar conversion of 1,5 pentanediol exhibited a higher selectivity towards linear alcohols. Alcohol conversion found to correlate with total acidity (i.e., Br?nsted and Lewis). CeO2 benefited from the addition of alkali (Na) or alkaline earth metals (Mg, Ca) by producing unsaturated alcohols.
- Cronauer, Donald C.,Góra-Marek, Kinga,Garcia, Richard,Gnanamani, Muthu Kumaran,Jacobs, Gary,Kropf, A. Jeremy,Marshall, Christopher L.
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- Revisiting the role of acids and hydrogen bond acceptors in enamine formation
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A systematic investigation into the effects of acids and hydrogen bond acceptors on the reaction rates and equilibria of enamine formation is reported. Acids can accelerate the reaction but do not change the reaction equilibria. In comparison, hydrogen bond acceptors facilitate the enamine formation via their strong hydrogen bonding interaction with the water generated in the reaction.
- Hammond, Gerald B.,Lu, Zhichao,Xu, Bo
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supporting information
p. 6849 - 6852
(2020/10/02)
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- One-pot biosynthesis of 1,6-hexanediol from cyclohexane by: De novo designed cascade biocatalysis
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1,6-Hexanediol (HDO) is an important precursor in the polymer industry. The current industrial route to produce HDO involves energy intensive and hazardous multistage (four-pot-four-step) chemical reactions using cyclohexane (CH) as the starting material, which leads to serious environmental problems. Here, we report the development of a biocatalytic cascade process for the biotransformation of CH to HDO under mild conditions in a one-pot-one-step manner. This cascade biocatalysis operates by using a microbial consortium composed of three E. coli cell modules, each containing the necessary enzymes. The cell modules with assigned functions were engineered in parallel, followed by combination to construct E. coli consortia for use in biotransformations. The engineered E. coli consortia, which contained the corresponding cell modules, efficiently converted not only CH or cyclohexanol to HDO, but also other cycloalkanes or cycloalkanols to related dihydric alcohols. In conclusion, the newly developed biocatalytic process provides a promising alternative to the current industrial process for manufacturing HDO and related dihydric alcohols. This journal is
- Kang, Lixin,Li, Aitao,Li, Qian,Li, Renjie,Wang, Fei,Yu, Xiaojuan,Zhang, Zhongwei,Zhao, Jing
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p. 7476 - 7483
(2020/11/23)
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- A Deoximation Method for Deprotection of Ketones and Aldhydes Using a Graphene-Oxide-Based Co-catalysts System
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The deoximation of a wide range of ketoximes and aldoximes to their corresponding carbonyl compounds with high yields has been achieved using graphene oxide (GO) and sodium nitrite (NaNO2) as highly efficient catalysts and air as the green oxidant under mild conditions. The mechanism of deprotection and recycling use of catalyst were revealed in deep experiment. The carboxylic acid groups on the GO were essential for high catalytic activity. (Figure presented.).
- Tong, Qiaolin,Liu, Yang,Gao, Xuezhi,Fan, Zhanfang,Liu, Tianfu,Li, Bo,Su, Dangsheng,Wang, Qinghe,Cheng, Maosheng
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supporting information
p. 3137 - 3145
(2019/05/01)
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- Novel Old Yellow Enzyme Subclasses
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Many drug candidate molecules contain at least one chiral centre, and consequently, the development of biocatalytic strategies to complement existing metal- and organocatalytic approaches is of high interest. However, time is a critical factor in chemical process development, and thus, the introduction of biocatalytic steps, even if more suitable, is often prevented by the limited availability of off-the-shelf enzyme libraries. To expand the biocatalytic toolbox with additional ene reductases, we screened 19 bacterial strains for double bond reduction activity by using the model substrates cyclohexanone and carvone. Overall, we identified 47 genes coding for putative ene reductases. Remarkably, bioinformatic analysis of all genes and the biochemical characterization of four representative novel ene reductases led us to propose the existence of two new Old Yellow Enzyme subclasses, which we named OYE class III and class IV. Our results demonstrate that although, on a DNA level, each new OYE subclass features a distinct combination of sequence motifs previously known from the classical and the thermophilic-like group, their substrate scope more closely resembles the latter subclass.
- Peters, Christin,Frasson, David,Sievers, Martin,Buller, Rebecca
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p. 1569 - 1577
(2019/05/15)
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- Efficient Palladium(0) supported on reduced graphene oxide for selective oxidation of olefins using graphene oxide as a ‘solid weak acid’
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Selective oxidation of olefin derivatives to ketones has made innovative development over palladium(0) supported on reduced graphene oxide. Compared to traditional Wacker oxidation, the novel method offers an economical and environment-friendly option by using graphene oxide (GO) as a ‘solid weak acid’ instead of classical homogeneous catalysts like H2SO4 and CF3COOH. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscopy images of Pd0/RGO showed that the nanoscaled Pd particles generated at the flake structure of reduced graphene oxide. Under optimized condition, up to 44 kinds of ketones with different structures can be prepared with excellent yields.
- Gao, Xi,Zhou, Jianhao,Peng, Xinhua
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