- A simple and effective catalytic system for epoxidation of aliphatic terminal alkenes with manganese(II) as the catalyst
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A simple catalytic system that uses commercially available manganese(II) Perchlorate as the catalyst and peracetic acid as the oxidant is found to be very effective in the epoxidation of aliphatic terminal alkenes with high product selectivity at ambient temperature. Many terminal alkenes are epoxidised efficiently on a gram scale in less than an hour to give excellent yields of isolated product (>90%) of epoxides in high purity. Kinetic studies with some C9-alkenes show that the catalytic system is more efficient in epoxidising terminal alkenes than internal alkenes, which is contrary to most commonly known epoxidation systems. The reaction rate for epoxidation decreases in the order: 1-nonene>cis-3-nonene> trans-3-nonene. ESI-MS and EPR spectroscopic studies suggest that the active form of the catalyst is a high-valent oligonuclear manganese species, which probably functions as the oxygen atomtransfer agent in the epoxidation reaction.
- Ho, Kam-Piu,Wong, Wing-Leung,Lam, Kin-Ming,Lai, Cheuk-Piu,Chan, Tak Hang,Wong, Kwok-Yin
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- A bulky bis-pocket manganese(V)-oxo corrole complex: Observation of oxygen atom transfer between triply bonded MnV≡O and alkene
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(Graph Presented) The highly bulky bis-pocket corrole 5,10,15-tris(2,4,6- triphenylphenyl)corrole (H3TTPPC) has been synthesized. Resonance Raman spectroscopy revealed a triply bonded Mn≡O moiety in its manganese(V)-oxo complex. Direct oxygen atom transfer from (TTPPC)Mn≡O to styrene was confirmed by an 18O-labeling experiment. The (TTPPC)MnIII complex also exhibits significant shape selectivity in the catalytic epoxidation of nonconjugated dienes.
- Liu, Hai-Yang,Yam, Fei,Xie, Yu-Tao,Li, Xiao-Yuan,Chang, Chi K.
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- Optimisation of alkene epoxidation catalysed by polymer supported Mo(VI) complexes and application of artificial neural network for the prediction of catalytic performances
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A greener and efficient alkene epoxidation process using heterogeneous molybdenum (Mo) based catalysts and tert-butyl hydroperoxide (TBHP) as an oxidant has been developed. A polybenzimidazole supported Mo(VI) complex, i.e. PBI.Mo and polystyrene 2-(aminomethyl) pyridine supported Mo(VI) complex, i.e. Ps.AMP.Mo catalysts have been successfully prepared and characterised. The catalytic activities of the polymer supported Mo(VI) catalysts have been tested for epoxidation of 1-hexene and 4-vinyl-1-cyclohexene in a jacketed stirred batch reactor. Batch experiments have been conducted to study the effect of different types of catalysts, catalyst loading, feed mole ratio (FMR) of alkene to TBHP and reaction temperature on the yield of epoxide for both alkenes, i.e. 1-hexene and 4-vinyl-1-cyclohexene. The long-term stability of PBI.Mo and Ps.AMP.Mo catalysts has been evaluated by recycling the catalyst several times for batch experiments using conditions that will form the basis of a continuous epoxidation process. The extent of Mo leaching from each polymer supported catalyst has been investigated by isolating any residue from reaction supernatant solutions after the removal of the heterogeneous catalyst and using the residue as potential catalyst for epoxidation. An artificial neural network (ANN) model has been employed to predict the catalytic performance of PBI.Mo and Ps.AMP.Mo catalysts for all batch experimental results. The ANN predicted values are in good agreement with the batch experimental results. The results obtained from batch experiments and ANN modelling provided useful information for conducting continuous epoxidation experiments in multi-functional reactors such as FlowSyn and reactive distillation column (RDC).
- Mohammed, Misbahu Ladan,Patel, Dipesh,Mbeleck, Rene,Niyogi, Debdarsan,Sherrington, David C.,Saha, Basudeb
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- Tris(pyrazolyl)methane molybdenum tricarbonyl complexes as catalyst precursors for olefin epoxidation
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The molybdenum tricarbonyl complexes [Mo(CO)3(HC(3,5-Me 2pz)3)] (1) and [Mo(CO)3(HC(pz)3)] (2) (HC(3,5-Me2pz)3 = tris(3,5-dimethyl-1-pyrazolyl) methane, HC(pz)3 = tris(1-pyrazolyl)methane) were obtained in good yields by the microwave-assisted reaction of Mo(CO)6 with the respective organic ligand. Complete oxidative decarbonylation of 1 and 2 was achieved by reaction with excess tert-butylhydroperoxide (TBHP) in 1,2-dichloroethane at 55 °C. For complex 1, the (μ2-oxo) bis[dioxomolybdenum(VI)] hexamolybdate of composition [{MoO2(HC(3,5- Me2pz)3)}2(μ2-O)][Mo 6O19] (3) was obtained in good yield, and its structure was determined by single crystal X-ray diffraction. The compound (4) obtained by oxidative decarbonylation of 2 was not unambiguously identified, but may be chemically analogous to 3. Compounds 1-4 were examined for the first time as homogeneous (pre)catalysts for the epoxidation of olefins with TBHP, using different types of cosolvents at 55 °C. During the catalytic reactions 1 and 2 transform in situ into 3 and 4, respectively, and the latter two are fairly stable catalysts. Catalytic tests and characterization studies of the recovered catalysts were carried out in an attempt to understand the kinetic differences observed between the compounds prepared in situ during the catalytic reaction and those prepared prior to the catalytic reaction, from the same precursor complex.
- Gomes, Ana C.,Neves, Patrícia,Figueiredo, Sónia,Fernandes, José A.,Valente, Anabela A.,Almeida Paz, Filipe A.,Pillinger, Martyn,Lopes, André D.,Gon?alves, Isabel S.
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- A Recoverable Ruthenium Aqua Complex Supported on Silica Particles: An Efficient Epoxidation Catalyst
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The preparation and characterization of complexes with a phosphonated terpyridine (trpy) ligand (trpy-P-Et) and a bidentate pyridylpyrazole (pypz-Me) ligand, with formula [RuII(trpy-P-Et)(pypz-Me)X]n+ (2: X=Cl, n=1; 3: X=H2O, n=2), is described, together with the anchoring of 3 on two types of supports: mesoporous silica particles (SP) and silica-coated magnetic particles (MSP). Aqua complex 3 is easily obtained by heating 2 in refluxing water and exhibits a two-electron RuIV/II redox process. It was anchored on SP and MSP supports by two different synthetic strategies, yielding the heterogeneous systems SP@3 and MSP@3, which were fully characterized by IR and UV/Vis spectroscopy, SEM, cyclic voltammetry, and differential pulse voltammetry. Catalytic olefin epoxidation was tested with molecular complex 3 and its SP@3 and MSP@3 heterogeneous counterparts, including reuse of the heterogeneous systems. The MSP@3 material can be easily recovered by a magnet, which facilitates its reusability.
- Ferrer, íngrid,Fontrodona, Xavier,Roig, Anna,Rodríguez, Montserrat,Romero, Isabel
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- Efficient, regioselective epoxidation of dienes with hydrogen peroxide catalyzed by [γ-SiW10O34(H2O) 2]4-
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A divacant, lacunary, Keggin-type silicotungstate, [γ-SiW 10O34(H2O)2]4-, exhibits high catalytic performance for the epoxidation of various nonconjugated dienes using hydrogen peroxide under mild conditions, high regioselectivity to the more accessible double bonds, and high efficiency of hydrogen peroxide utilization. The high regioselectivity for the [γ-SiW10O34(H 2O)2]4--catalyzed epoxidation would be caused by the steric hindrance of the active site.
- Kamata, Keigo,Nakagawa, Yoshinao,Yamaguchi, Kazuya,Mizuno, Noritaka
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- EPOXIDATION OF OLEFINS BY HYDROGEN PEROXIDE IN THE PRESENCE OF TETRACHLOROACETONE
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1,1,3,3-Tetrachloroacetone, an inexpensive, commercially available material, has been shown to be effective in mediating the hydrogen peroxide oxidation of a variety of olefins to epoxides.The chloroacetone is readily recovered for re-use.
- Stark, Charles J.
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- Epoxidation of allyl chloride to epichlorohydrin by a reversible supported catalyst with H2O2 under solvent-free conditions
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Allyl chloride was epoxidized to epichlorohydrin with H2O 2 under solvent-free conditions in 94% selectivity using a new reversible supported catalyst, heteropolyphosphatotungstate/silanized silica gel. By the action of H2O2 the heteropolyphosphatotungstate dissolves from the carrier surface and forms an active homogeneous reagent. When all H2O2 is consumed, the reduced catalyst redeposits on the support carrier. The supported catalyst retains the character of a homogeneous catalyst during reaction but exhibits heterogeneous properties upon work-up. The solid-supported catalyst is easily isolated and can be reused. The reaction system for synthesis of epichlorohydrin therefore avoids the serious pollution issues known from the commercialized chlorohydrin methods. Some other olefins can also be epoxidized by this catalytic system under neat conditions.
- Li, Jun,Zhao, Gongda,Gao, Shuang,Lv, Ying,Li, Jian,Xi, Zuwei
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- Stereospecific and regioselective catalytic epoxidation of alkenes by a novel ruthenium(II) complex under aerobic conditions
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Epoxidation of alkenes by molecular oxygen is effected in high yields by catalysis of RuCl2(biox)2 using isobutyraldehyde as the co-reductant: the reaction is stereospecific and regioselective.
- Kesavan, Venkitasamy,Chandrasekaran, Srinivasan
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- Synthesis of epoxides catalyzed by a halide-free reaction-controlled phase-transfer catalytic system: [(CH3(CH2) 17)2N(CH3)2]3[PW 4O32]/H2O2/Dioxan/Olefin
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The epoxidation of alkenes was successfully catalyzed by a recyclable catalytic system: [(CH3(CH2)17) 2N(CH3)2]3[PW4O 32]/H2O2/dioxan/olefin. This new catalytic system is not only capable of catalyzing homogeneous epoxidation of alkenes with a unique reaction-controlled phase-transfer character, but also avoids the use of chlorinated solvents. The reactions were conducted in a biphasic mixture of aqueous H2O2/dioxan, and many kinds of alkenes could be efficiently converted to the corresponding epoxides in high yields. Both new and used [(CH3(CH2)17)2N(CH 3)2]3[PW4O32] catalyst was characterized by 31P magic angle spin NMR, and IR. CSIRO 2009.
- Ding, Yong,Ma, Baochun,Tong, Dejie,Hua, Hui,Zhao, Wei
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- Metal silicates by a molecular route as catalysts for epoxidation of alkenes with tert-butyl hydroperoxide
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Macroporous, site isolated metal silicates are synthesized by a molecular route; the molybdenum silicate is especially active for the selective epoxidation of alkenes with tert-butyl hydroperoxide.
- Juwiler, David,Blum, Jochanan,Neumann, Ronny
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- New aqua N-heterocyclic carbene Ru(II) complexes with two-electron process as selective epoxidation catalysts: An evaluation of geometrical and electronic effects
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New ruthenium complexes with general formula [RuII(T)(CN-Me)X] n+ (X = Cl- or H2O; T = 2,2′:6′, 2″-terpyridine, trpy, or N,N-bis(2-pyridyl)ethylamine, bpea; CN-Me = N-methyl-N′-2-pyridylimidazolium) have been prepared. The complexes obtained have been characterized in solution by spectroscopic (1D- and 2D-NMR and UV-vis) techniques, mass spectrometry, and elemental analysis. The chloro complexes have also been characterized by X-ray diffraction analysis. The redox properties of all the compounds were studied by CV revealing, for the reported Ru-OH2 complexes, bielectronic Ru(IV/II) redox processes throughout a wide pH range. The catalytic activity of aquo complexes was evaluated in the epoxidation of olefins using PhIO as oxidant, displaying in general good yields and high selectivities for the epoxide product. The influence of electronic and geometrical factors on the spectroscopic and electrochemical properties as well as on the catalytic activity is discussed.
- Dakkach, Mohamed,Atlamsani, Ahmed,Parella, Teodor,Fontrodona, Xavier,Romero, Isabel,Rodriguez, Montserrat
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- New Ru(II) complexes with anionic and neutral N-donor ligands as epoxidation catalysts: An evaluation of geometrical and electronic effects
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The synthesis of a family of new Ru complexes containing the meridional trpy ligand with general formula [RuII(T)(D)(X)]n+ (T = 2,2′:6′,2″-terpyridine (trpy); D = 3,5-dimethyl-2-(2-pyridyl) pyrrolate (pyrpy), and 2-(1-Methyl-3-pyrazolyl)pyridine (pypz-Me); X = Cl, H2O) have been described. All complexes have been spectroscopically characterized in solution through 1H NMR and UV-vis techniques, and the chloro complexes have also been characterized in the solid state through monocrystal X-ray diffraction analysis. The pyrpy ligand undergoes an oxidation at the 3-position of the pyrrolate ring during the formation of the corresponding aqua complex thus generating the analogous compound containing the oxidized ligand pyrpy-O. The redox properties of all complexes have also been studied by means of CV and DPV techniques, where both geometrical (trans vs cis) and electronic (neutral vs anionic) effects can be unveiled and rationalized. Finally, the reactivity of the whole set of Ru-OH2 complexes has been tested with regard to the epoxidation of different alkenes with PhI(OAc) 2. In all cases good selectivities and conversions were obtained. Furthermore, total retention of the initial cis configuration was achieved when using these catalysts to epoxidize cis-β-methylstyrene.
- Dakkach, Mohamed,Lopez, M. Isabel,Romero, Isabel,Rodriguez, Montserrat,Atlamsani, Ahmed,Parella, Teodor,Fontrodona, Xavier,Llobet, Antoni
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- Highly selective epoxidation of cycloaliphatic alkenes with aqueous hydrogen peroxide catalyzed by [PO4{WO(O2) 2}4]3-/imidazole
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In the presence of imidazole as an additive, a phosphorus-containing tetranuclear peroxotungstate, THA3[PO4{WO(O 2)2}4] (I, THA=tetra-n-hexylammonium), could act as an efficient catalyst for epoxidation of cycloaliphatic alkenes with 30% aqueous hydrogen peroxide (H2O2). Compound I showed higher catalytic activity and selectivity to epoxide than other tungstates. By using the I/imidazole system, various kinds of cycloaliphatic alkenes could be highly selectively converted into the acid-sensitive epoxides including industrially important diepoxides in high to excellent yields under the almost stoichiometric conditions. The 1H NMR spectroscopy showed that imidazole would work not only as a proton acceptor but also as a Lewis base to remarkably suppress the acid-catalyzed ring opening of epoxides.
- Kamata, Keigo,Sugahara, Kosei,Ishimoto, Ryo,Nojima, Susumu,Okazaki, Motoya,Matsumoto, Takaya,Mizuno, Noritaka
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- Polypyrrole-functionalized ruthenium carbene catalysts as efficient heterogeneous systems for olefin epoxidation
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New Ru complexes containing the bpea-pyr ligand (bpea-pyr stands for N,N-bis(pyridin-2-ylmethyl)-3-(1H-pyrrol-1-yl)propan-1-amine), with the formula [RuCl2(bpea-pyr)(dmso)] (isomeric complexes 2a and 2b) or [Ru(CN-Me)(bpea-pyr)X)]n+ (CN-Me = 3-methyl-1-(pyridin-2-yl)-1H- imidazol-3-ium-2-ide; X = Cl, 3, or X = H2O, 4), have been prepared and fully characterized. Complexes 3 and 4 have been anchored onto an electrode surface through electropolymerization of the attached pyrrole group, yielding stable polypyrrole films. The electrochemical behaviour of 4, which displays a bielectronic Ru(IV/II) redox pair in solution, is dramatically affected by the electropolymerization process leading to the occurrence of two monoelectronic Ru(IV/III) and Ru(III/II) redox pairs in the heterogeneous system. A carbon felt modified electrode containing complex 4 (C-felt/poly-4) has been evaluated as a heterogeneous catalyst in the epoxidation of various olefin substrates using PhI(OAc)2 as an oxidant, displaying TON values of several thousands in all cases and good selectivity for the epoxide product.
- Dakkach, Mohamed,Fontrodona, Xavier,Parella, Teodor,Atlamsani, Ahmed,Romero, Isabel,Rodriguez, Montserrat
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- A Ruthenium(II) Aqua Complex as Efficient Chemical and Photochemical Catalyst for Alkene and Alcohol Oxidation
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Different synthetic routes have been developed to obtain the aqua complex trans-[RuII(trpy)(pypz-H)(OH2)](PF6)2, Ru6. This complex, together with the chlorido intermediate complexes cis- and trans-[RuIICl(pypz-H)(trpy)]+, Ru5a and Ru5b, have been fully characterized by analytical, spectroscopic, and electrochemical methods. Furthermore, the trans-Ru5b complex has been characterized in the solid state through single-crystal X-ray diffraction analysis. The aqua complex Ru6 was tested as catalyst in the photooxidation of alcohols in water and in the chemical oxidation of alkenes, displaying a good performance with high selectivity values in both catalytic processes.
- Manrique, Ester,Fontrodona, Xavier,Rodríguez, Montserrat,Romero, Isabel
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- Catalysis of alkene epoxidation by a series of gallium(III) complexes with neutral N-donor ligands
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Six gallium(III) complexes with N-donor ligands were synthesized to study the mechanism of GaIII-catalyzed olefin epoxidation. These include 2:1 ligand/metal complexes with the bidentate ligands ethylenediamine, 5-nitro-1,10-phenanthroline, and 5-amino-1,10-phenanthroline, as well as 1:1 ligand/metal complexes with the tetradentate N,N′-bis(2-pyridylmethyl)-1, 2-ethanediamine, the potentially pentadentate N,N,N′-tris(2-pyridylmethyl) -1,2-ethanediamine, and the potentially hexadentate N,N,N′,N′- tetrakis(2-pyridylmethyl)-1,2-ethanediamine. In solution, each of the three pyridylamine ligands appears to coordinate to the GaIII through four donor atoms. The six complexes were tested for their ability to catalyze the epoxidation of alkenes by peracetic acid. Although the complexes with relatively electron-poor phenanthroline derivatives display faster initial reactivity, the gallium(III) complexes with the polydentate pyridylamine ligands appear to be more robust, with less noticeable decreases in their catalytic activity over time. The more highly chelating trispicen and tpen are associated with markedly decreased activity.
- Jiang, Wenchan,Gorden, John D.,Goldsmith, Christian R.
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- A novel carbene ruthenium complex as reusable and selective two-electron catalyst for alkene epoxidation
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A new ruthenium aquo catalyst with the formula trans-[Ru(II)(CN-Me)(trpy) OH2](PF6)2 [where trpy=2,2a:6′,2″- terpyridine and CN-Me=3-methyl-1-(pyridin-2-yl)-imidazolylidene] has been prepared and thoroughly characterized by spectroscopic and electrochemical techniques. The complex has been tested in epoxidation catalysis both in dichloromethane and dichloromethane:ionic liquid media, displaying excellent performances and selectivities. Reuse of the catalyst in ionic liquid:solvent media has been explored for the first time in ruthenium-mediated epoxidation catalysis and its performance is fully maintained for up to ten runs.
- Dakkach, Mohamed,Fontrodona, Xavier,Parella, Teodor,Atlamsani, Ahmed,Romero, Isabel,Rodriguez, Montserrat
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- A homogeneous gallium(III) compound selectively catalyzes the epoxidation of alkenes
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We demonstrate that a simple gallium(III) complex, [Ga(phen) 2Cl2]Cl (phen = 1,10-phenanthroline), can serve as a homogeneous catalyst for the epoxidation of alkenes. The olefin epoxidations proceed relatively quickly at mild temperatures and, under optimum conditions, are highly selective for the epoxide product.
- Jiang, Wenchan,Gorden, John D.,Goldsmith, Christian R.
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- A broad substrate-scope method for fast, efficient and selective hydrogen peroxide-epoxidation
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The efficient epoxidation of a broad range of olefins using hydrogen peroxide (H2O2) as the oxidant has been accomplished by a manganese catalyst that exhibits an uncommon chemoselectivity.
- Garcia-Bosch, Isaac,Ribas, Xavi,Costas, Miquel
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- Aerobic epoxidation of alkenes catalysed by cobalt(II) 1,1,1,5,5,5-hexafluoroacetylacetonate or cobalt(II) benzoylacetonate
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The aerobic epoxidation of terminal or electron deficient alkenes with an aldehyde does not proceed with cobalt(II) acetylacetonate but goes to completion with the cobalt(II) benzoylacetonate and cobalt(II) 1,1,1,5,5,5-hexafluoroacetylacetonate complexes.
- Hunter,Turner,Rimmer
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- A stand-alone cobalt bis(dicarbollide) photoredox catalyst epoxidates alkenes in water at extremely low catalyst load
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The cobalt bis(dicarbollide) complex, Na[3,3′-Co(η5-1,2-C2B9H11) (Na[1]), is an effective photoredox catalyst for the oxidation of alkenes to epoxides in water. Advantageous features of Na[1] include its lack of photoluminescence, high solubility and surfactant behavior in aqueous media, as well as the donor ability of the carborane ligand and high oxidizing power of the Co4+/3+ couple. These features differentiate it from the well-known and widely used photosensitizer tris (2,2′-bipyridine) ruthenium(ii) ([Ru(bpy)3]2+), which also participates in electron transfer through an outer sphere mechanism. A comparison of the catalytic performance of [Ru(bpy)3]2+ with Na[1] for alkene photo-oxidation is fully in favor of Na[1], as the former shows very low or null efficiency. With a catalyst loading of 0.1 mol% conversions between 65-97% have been obtained in short reaction times, 15 minutes, with moderate selectivity for the corresponding epoxide, due to the formation of side products as diols. But when the catalyst loading is reduced to 0.01 mol%, the selectivity for the corresponding epoxide increased considerably, being the only compound formed after 15 minutes of reaction (selectivity >99%). High TON values have been obtained (TON = 8500) for the epoxidation of aromatic and aliphatic alkenes in water. We have verified that Na[3,3′-Co(η5-1,2-C2B9H11)2] acts as a photocatalyst in both the epoxidation of alkenes and in their hydroxylation in aqueous medium with a higher rate for epoxidation than for hydroxylation. Preliminary photooxidation tests using methyl oleate as the substrate led to the selective epoxidation of the double bond. These results represent a promising starting point for the development of practical methods for the processing of unsaturated fatty acids, such as the valorisation of animal fat waste using this sustainable photoredox catalyst. This journal is
- Guerrero, Isabel,Romero, Isabel,Teixidor, Francesc,Vi?as, Clara
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supporting information
p. 10123 - 10131
(2021/12/27)
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- METHOD FOR PRODUCING EPOXY COMPOUND
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The invention provides a method for producing an epoxy compound by hydrogen peroxide using an organic compound having a carbon-carbon double bond as a raw material, wherein a by-product is suppressed from being generated and the epoxy compound is produced in a high yield. In particular, the invention provides a method for producing an epoxy compound involving oxidizing a carbon-carbon double bond in an organic compound with hydrogen peroxide in the presence of a catalyst, wherein the catalyst comprises a tungsten compound; a phosphoric acid, a phosphonic acid or salts thereof; and an onium salt having an alkyl sulfate ion represented by formula (I) as an anion: wherein R1 is a linear or branched aliphatic hydrocarbon group having 1 to 18 carbons, which may be substituted with 1 to 3 phenyl groups.
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Paragraph 0089-0091
(2021/11/05)
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- 1,2-epoxy-4-vinylcyclohexane and preparation method thereof
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The invention relates to 1,2-epoxy-4-vinylcyclohexane. 1,2-epoxy-4-vinylcyclohexane is prepared from the following raw materials in percentage by mass: 12%-14% of 4-vinyl-1-cyclohexene, 40%-45% of toluene, 17%-19% of acetic anhydride, 2%-4% of sodium acetate and 21%-23% of 35% hydrogen peroxide. The invention further relates to a preparation method of 1,2-epoxy-4-vinylcyclohexane. Prepared 1,2-epoxy-4-vinylcyclohexane has high yield and selectivity, and purity of a reaction product is improved; besides, 1,2-epoxy-4-vinylcyclohexane has low chlorine content and has no heavy metal residues, andgelation time of the product is short.
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Paragraph 0027-0068
(2018/06/26)
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- Reusable manganese compounds containing pyrazole-based ligands for olefin epoxidation reactions
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We describe the synthesis of new manganese(ii) and manganese(iii) complexes containing the bidentate ligands 2-(3-pyrazolyl)pyridine, pypz-H, and 3(5)-(2-hydroxyphenyl)pyrazole, HOphpz-H, with formula [MnX2(pypz-H)2] (X = Cl-, 1, CF3SO3-, 2, OAc-, 3 or NO3- (4)), [MnCl2(pypz-H)(H2O)2], 5, or [MnCl(Ophpz-H)2], 6. All the complexes have been characterized through analytical, spectroscopic and electrochemical techniques. Single X-ray structure analysis revealed a six-coordinated Mn(ii) ion in complexes 1-5, and a five-coordinated Mn(iii) ion in complex 6. Compound 5 is the first co-crystal of Mn(ii) containing Cl and H2O ligands together with bidentate nitrogen ligands. The catalytic activity of complexes 1-6 has been tested with regard to the epoxidation of styrene and, in the case of 1, 5 and 6, other alkenes have been epoxidized using peracetic acid as oxidant in different media, among which glycerol, a green solvent never used in epoxidation reactions using peracetic acid as oxidant. The catalysts show moderate to high conversions and selectivities towards the corresponding epoxides. For complexes 1, 5 and 6, a certain degree of cis → trans isomerization is observed in the case of cis-β-methylstyrene. These observations have been explained through computational calculations. The reutilization of catalysts 1 and 6 for the epoxidation of alkenes has been evaluated in [bmim]:acetonitrile mixture (bmim = 1-butyl-3-methylimidazolium), allowing the effective recyclability of the catalytic system and keeping high conversion and selectivity values up to 12 successive runs, in all cases.
- Manrique, Ester,Poater, Albert,Fontrodona, Xavier,Solà, Miquel,Rodríguez, Montserrat,Romero, Isabel
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p. 17529 - 17543
(2015/10/19)
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- A new halide-free efficient reaction-controlled phase-transfer catalyst based on silicotungstate of [(C18H37)2(CH 3)2N]3[SiO4H(WO5) 3] for olefin epoxidation, oxidation of sulfides and alcohols with hydrogen peroxide
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A new reaction-controlled phase-transfer catalyst based on silicotungstate of [(C18H37)2(CH3) 2N]3[SiO4H(WO5)3] for oxidation of hydrocarbons is developed. The catalyst is a new heteropoly compound with silicon as heteroatom, which is different to the previously reported reaction-controlled phase transfer catalysts that were composed of quaternary ammonium heteropolyoxotungstates of [π-C5H 5N(CH2)15CH3]3[PW 4O16] and [π-C5H5N(CH 2)15CH3]3[PW4O 32] with phosphorus as heteroatom. The oxidation of various alkenes (such as linear terminal olefins, internal olefins, cyclic olefins and unactivated alkenes) to epoxides, sulfides to sulfoxides and sulfones, alcohols to carbonyl compounds, are successfully catalyzed by this recyclable and environmentally benign catalyst using H2O2 as oxidant and ethyl acetate as solvent. This catalyst is not only capable of catalyzing homogeneous oxidation of organic substrates with unique reaction-controlled phase-transfer character, but also avoids the use of toxic solvents. The catalyst could be easily recovered and reused after reaction, and the epoxidation of cyclohexene was performed twenty times without obvious loss in activity. The fresh catalyst and the used one were characterized by ICP, IR, UV-vis, 29Si MAS NMR and 183W NMR in detail. the Partner Organisations 2014.
- Ma, Baochun,Zhao, Wei,Zhang, Fuming,Zhang, Yingshuai,Wu, Songyun,Ding, Yong
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p. 32054 - 32062
(2014/08/18)
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- Oxidative dihydroxylation of alicyclic unsaturated hydrocarbons with vinyl- and norbornene fragments in pseudohomogenic system
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Oxidation of alicyclic unsaturated hydrocarbons (4-vinylcyclohexene, 5-vinylnorbornene, 5-cyclohexenylnorbornene, and 5-vinylbicyclooctene) with 30% hydrogen peroxide solutions and percarbamide is studied. Reaction was carried out at 40-70 C in the presence of heterogenized peroxocomplex compounds of molybdenum and tungsten formed "in situ" in the reaction of metal oxohalides with H3PO4, nano-dimensional particles of carbon material, and hydrogen peroxide. Main oxidation products of alicyclic diene hydro-carbons are the corresponding unsaturated epoxides and diols. Depending on the reaction condition their ratio varies in a wide range.
- Alimardanov, Kh. M.,Garibov,Abdullaeva, M. Ya.,Sadygov,Kuliev,Ismailov
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- Designing the synthesis of catalytically active Ti-β by using various new templates in the presence of fluoride anion
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Crystallization of large-pore Ti-β by using a variety of diquaternary ammonium derivatives of dibromoalkane and amines such as triethylamine, 1,4-diazabicyclo[2,2,2]octane (DABCO), and quinuclidine as structure-directing agents (SDA) is described. The size of hydrophobic bridging alkyl-chain length of the template [R3N+-(CH2)x-N +R3](OH-)2 directs the final crystalline product: Ti-β, Ti-ZSM-12, Ti-nonasil or Ti-ZSM-5, as x gradually changes from 6 to 1, in the fluoride medium under hydrothermal conditions. A dense phase such as Ti-nonasil (clathrasil type) is crystallized as the size of hydrophobic bridging alkyl-chain length decreases. The use of F- anions as a mineralizer and Ti4+ as a heteroatom in the synthesis gel also influences the selectivity of final crystalline product. The phase purity and incorporation of Ti4+ into the lattice of β (BEA) and ZSM-12 frameworks are confirmed using XRD, UV-visible, FT-IR, 29Si NMR spectroscopes, elemental analysis (ICP), surface area measurements and catalytic test reactions. The morphology of Ti-β samples is dependent on the nature of the structure-directing agent as revealed by the scanning electron microscopic (SEM) observations. The catalytic activity in the epoxidation of 4-vinyl-1-cyclohexene is increased with the amount of tetrahedral Ti4+ atoms in the framework. The new templates can be effectively used for preparation of catalytically active Ti-β with the minimum number of framework defect sites.
- Sasidharan, Manickam,Bhaumik, Asim
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experimental part
p. 16282 - 16294
(2012/01/14)
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- New Ru(II) complexes containing oxazoline ligands as epoxidation catalysts. Influence of the substituents on the catalytic performance
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The synthesis of a family of new Ru complexes containing the facial tridentate ligand with general formula [RuII(T)(D)(X)]n+ (T = trispyrazolylmethane (tpm); D = ((4S,4′S)-(-)-4,4′,5,5′- tetrahydro-4,4′-bis(1-methylethyl)-2,2′-bioxazole) (iPr-box-C) or N-(1-hydroxy-3-methylbutan-(2S)-(-)-2-yl)-(4S)-(-)-4-isopropyl-4, 5-dihydrooxazole-2-carbimidate (iPr-box-O); X = Cl, H2O) has been described. All complexes have been spectroscopically characterized in solution through 1H NMR and UV-vis techniques, and the redox properties of complexes have also been studied by means of cyclic voltammetry (CV). Furthermore, the chloro complexes presented here have been characterized in the solid state through monocrystal X-ray diffraction analysis. The oxazolinic iPr-box-C ligand undergoes a Ru-assisted hydrolysis reaction generating the corresponding amidate anionic ligand iPr-box-O, that keeps coordinated to the Ru metal center and that produces a strong σ-donation effect over it. The reactivity of the Ru-OH2 complexes described in this paper together with other similar ones, previously synthesized by us, has been tested with regard to the epoxidation of different olefins. Complexes [Ru II(R-box-C)(tpm)OH2](BF4)2, R = Bz, 3′c/iPr, 3c, show high stereoselectivity in the epoxidation of cis-β-methylstyrene, with the exclusive formation of the cis-epoxide. However, there is a significant difference in regioselectivity between the two catalysts in the epoxidation of 4-vinylcyclohexene; complex 3′c leads to the regioselective oxidation at the ring alkene position, whereas complex 3c leads to the oxidation at the terminal position. Computational calculations indicate only small energy differences between the two possible products of 4-vinylcyclohexene epoxidation, but the energy barriers for the interaction of the catalytic systems with the alkene groups of 4-vinylcyclohexene agree with the reactivity differences found for the two catalysts having isopropyl or benzyl as substituent of the oxazole ligand. Computed local Fukui functions help to explain the observed reactivity trends.
- Serrano, Isabel,Lopez, M. Isabel,Ferrer, Ingrid,Poater, Albert,Parella, Teodor,Fontrodona, Xavier,Sola, Miquel,Llobet, Antoni,Rodriguez, Montserrat,Romero, Isabel
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experimental part
p. 6044 - 6054
(2011/09/13)
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- Regioselective epoxidation of different types of double bonds over large-pore titanium silicate Ti-β
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Regioselective epoxidation of different types of double bonds located within the cyclic and acyclic parts of bulky olefins has been investigated using large-pore titanium silicate Ti-β in the presence of dilute aqueous H 2O2 as oxidant under mild liquid-phase conditions. Our experimental results revealed that side-chain vinylic double bonds are selectively epoxidized than those in the cyclohexene-ring. The epoxidation tendency of various bulky olefins with different positional and/or geometric isomers over Ti-β follows the order: terminal -CC- > ring -CC- ≈ bicyclic ring -CC- > allylic C - H bond. Unlike 4-vinyl-1-cyclohexene, epoxidation of an equimolar mixture of cyclohexene and 1-hexene under identical conditions using Ti-β exhibits completely different selectivity and product distributions. Steric factor and accessibility of reactants to active Ti-sites are responsible for the observed regioselectivity of bulky alkenes.
- Sasidharan, Manickam,Bhaumik, Asim
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experimental part
p. 60 - 67
(2010/12/18)
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- Novel N-phosphonio imine-catalyzed epoxidation reactions
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(Chemical Equation Presented) A new type of acyclic N-phosphonio imine catalyst for selective epoxidations has been synthesized. The activity of these imine catalysts can easily be modulated by varying its substituents. The substituent attached to the imine nitrogen atom is particularly important for an efficient oxygen transfer.
- Prieur, David,El Kazzi, Aimee,Kato, Tsuyoshi,Gornitzka, Heinz,Baceiredo, Antoine
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supporting information; experimental part
p. 2291 - 2294
(2009/05/11)
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- Olefin epoxidation with hydrogen peroxide catalyzed by lacunary polyoxometalate [γ-SiW10O34(H2O) 2]4-
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The tetra-n-butylammonium (TBA) salt of the divacant Keggin-type polyoxometalate [TBA]4[γ-SiW10O34-(H 2O)2] (I) catalyzes the oxygen-transfer reactions of olefins, allylic alcohols, and sulfides with 30% aqueous hydrogen peroxide. The negative Hammett ρ+ (-0.99) for the competitive oxidation of p-substituted styrenes and the low value of (nucleophilic oxidation)/(total oxidation), Xso = 0.04, for I-catalyzed oxidation of thianthrene 5-oxide (SSO) reveals that a strongly electrophilic oxidant species is formed on I. The preferential formation of trans-spoxide during epoxidation of 3-methyl-1-cyclohexene demonstrates the steric constraints of the active site of I. The I-catalyzed epoxidation proceeds with an induction period that disappears upon treatment of I with hydrogen peroxide. 29Si and 183W NMR spectroscopy and CSI mass spectrometry show that reaction of I with excess hydrogen peroxide leads to fast formation of a diperoxo species, [TBA]4[γ-SiW10O32(O2) 2] (II), with retention of a γ-Keggin type structure. Whereas the isolated compound II is inactive for stoichiometric epoxidation of cyclooctene, epoxidation with II does proceed in the presence of hydrogen peroxide. The reaction of II with hydrogen peroxide would form a reactive species (III), and this step corresponds to the induction period observed in the catalytic epoxidation. The steric and electronic characters of III are the same as those for the catalytic epoxidation by I. Kinetic, spectroscopic, and mechanistic investigations show that the present epoxidation proceeds via III.
- Kamata, Keigo,Kotani, Miyuki,Yamaguchi, Kazuya,Hikichi, Shiro,Mizuno, Noritaka
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p. 639 - 648
(2007/10/03)
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- Catalytic epoxidation of olefins in the presence of a vanadyl porphyrin complex
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It was found that vanadyl porphyrin complexes synthesized from petroleum metal porphyrin concentrates stimulated epoxidation during the olefin oxygenation process. The yields of obtained oxiranes turned out to be 38-75%, depending on the olefin structure. An epoxidation mechanism that suggests the formation of a protonated dioxygen adduct as an intermediate during oxygenation of olefins in the presence of vanadyl porphyrin complexes was proposed. An analogy is drawn between the epoxide formation reaction upon the catalytic oxygenation of olefins and the Prilezhaev reaction. MAIK "Nauka/Interperiodica".
- Miralamov,Mamedov
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- Trimanganese complexes bearing bidentate nitrogen ligands as a highly efficient catalyst precursor in the epoxidation of alkenes
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A series of trinuclear manganese complexes coordinated with neutral bidentate nitrogen ligands, [Mn3L2-(OAc)6], were prepared from manganese acetate and the corresponding ligands. Using peracetic acid as the oxidant, the air- and moisture-stable manganese clusters exhibited excellent catalytic activity and selectivity in the epoxidation of olefins under mild conditions. The highest activity was observed with a trinuclear complex containing a 2-pyridylimino ligand, [Mn3(ppei) 2(OAc)6] (ppei = 2-pyridinal-1-phenylethylimine). With this system, the substrate scope was extremely wide to include terminal and electron-deficient double bonds of both aliphatic and aromatic alkenes. The high activity was undiminished under the reaction conditions even directly using a mixture of the pyridylimino ligands and manganese acetates, making this process more convenient. It was also observed that analogous trinuclear complexes, such as [Mn3(bipy)2(OAc)6] and [Mn 3(phen)2(OAc)6], displayed excellent activities. While radical intermediacy was inferred from the product distribution, kinetic data revealed that the epoxidation is roughly first-order in manganese cluster precursor and oxidant, respectively, and zero-order in olefin. These results led us to propose that the trinuclear complexes [Mn 3L2(OAc)6] serve as catalyst precursors that dissociate into monomeric species with the formulation of [MnL 2(OAc)2] under the reaction conditions.
- Kang, Byungman,Kim, Min,Lee, Junseong,Do, Youngkyu,Chang, Sukbok
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p. 6721 - 6727
(2007/10/03)
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- Epoxidation of alkenes by hydrogen peroxide over 12-heteropolyacids of molybdenum and tungsten (H3PMo3W9O 40) combined with cetylpyridinium bromide
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In the epoxidation of 4-vinylcyclohex-1-ene with H2O2 in monophasic acetonitrile solution catalysed by Keggin-type 12-heteropolyacids, i.e., H3PMo12-nWnO 40 (n = 0-12), which are precursors of active peroxo complexes, and phase transfer catalysts Q+Br, the catalyst H3PMo 3W9O40 showed the highest activity, giving a conversion of 98% and a selectivity of 88%. By this method, a variety of water-insoluble unactivated alkenes, internal or terminal, open chain or cyclic and isolated, were epoxidised under mild conditions and after relatively short reaction times. The state of the H3PMo3W9O 40/CPB/H2O2/CH3CN system was studied using UV, IR, and 31P NMR spectroscopies with the [H 2O2]: [HPA] ratio = 50. Several peroxo species were observed by 31P NMR spectroscopy at a lower field than the original heteropolyacids. Their composition varied regularly with that of the starting catalyst. The P-containing peroxo species formed were deduced as [(PO 4){Mo4-xWxO20}]3- (x= 0-4), which are the true catalytically active species under the reaction conditions.
- Ding, Yong,Ma, Baochun,Gao, Qiang,Suo, Jishuan
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p. 499 - 503
(2007/10/03)
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- Construction of regulated nanospace around a porphyrin core
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A series of 1,3,5-phenylene-based rigid dendritic porphyrins were synthesized by Suzuki coupling between a porphyrin core and dendron units. The intramolecular energy transfer was studied by absorption and fluorescence spectroscopies. The encapsulation of the porphyrin core within the 1,3,5-phenylene dendron units was found to provide highly efficient energy transfer from the dendron units to the porphyrin core. The dendritic wedge structure affected the energy transfer efficiency. The 1,3,5-phenylene-based rigid dendron units act as highly efficient light-harvesting antennae. These dendritic porphyrins have also been examined as C60 hosts and substrate-selective oxidation catalysts. The attachment of the second generation of 1,3,5-phenylene-based dendron units with the porphyrin core enabled a stable inclusion of C60 in toluene. Furthermore, the size and shape of the nanospace in the rigid dendritic porphyrins were found to affect the selectivity of substrates in the catalytic olefin oxidations.
- Kimura,Shiba,Yamazaki,Hanabusa,Shirai,Kobayashi
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p. 5636 - 5642
(2007/10/03)
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- CATALYTIC DIHYDROXYLATION OF CYCLOHEXENE DERIVATIVES
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An investigation has been made of the dihydroxylation of 4-vinylcyclohexene, individual methylcyclohexenes and a mixture of 1,3-dimethylcyclohexane isomers.It has been established that the most effective catalyst is a complex produced by the reaction of molybdenum oxybromide, acetic acid and hydrogen peroxide.The yield of corresponding diols in the presence of this complex is 46-83.3percent, with a process selectivity of 70.0-90.7percent.The dependence of the direction of oxidation of cyclo-olefinic hydrocarbons on the nature and concentration of the organic acids used has been determined.
- Alimardanov, Kh. M.,Suleimanova, E. T.,Ismailov, E. G.,Akhundova, A. A.
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p. 333 - 339
(2007/10/02)
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- Oxidation of Organic Substrates by Molecular Oxygen/Aldehyde/ Heteropolyoxometalate System
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Heteropolyoxometalate-catalyzed oxidations of organic compounds such as olefins and cyclic ketones with molecular oxygen in the presence of an aldehyde were examined.Olefins were epoxidized with dioxygen in the presence of 2 equiv of 2-methylpropanal under the influence of a catalytic amount of the mixed heteropolyoxometalate NPV6Mo6 (3) to give the corresponding epoxides in moderate to good yields.This catalytic oxidation method was also applied to the epoxidation of allylic and homoallylic alcohols.In the absence of olefins, the aldehydes were efficiently convertedinto the corresponding carboxylic acids.In addition, the Baeyer-Villiger oxidation of cyclic ketones was accomplished by using benzaldehyde instead of 2-methylpropanal as the aldehyde.
- Hamamoto, Masatoshi,Nakayama, Kouichi,Nishiyama, Yutaka,Ishii, Yasutaka
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p. 6421 - 6425
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF EPOXIDES FROM OLEFINS USING MOLECULAR OXYGEN IN THE ABSENCE OF METAL CATALYSTS
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The system consisting of molecular oxygen and aldehydes (e.g., isobutyraldehyde and pivalaldehyde) oxidizes various olefins to give epoxides in high yields at 40 deg C for 3-6 h.Key Words: Epoxidation, Olefin, Molecular oxygen, Aldehyde
- Kaneda, Kiyotomi,Haruna, Shigeru,Imanaka, Toshinobu,Hamamoto, Masatoshi,Nishiyama, Yutaka,Ishii, Yasutaka
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p. 6827 - 6830
(2007/10/02)
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- Hydrogen Peroxide Oxidation Catalyzed by Heteropoly Acids Combined with Cetylpyridinium Chloride: Epoxidation of Olefins and Allylic Alcohols, Ketonization of Alcohols and Diols, and Oxidative Cleavage of 1,2-Diols and Olefins
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A general and versatile oxidation catalyst has been developed by using hydrogen peroxide as the oxidant.Olefins and allylic alcohols were epoxidized with commercially available hydrogen peroxide (30-35percent H2O2) using a combination of Mo- or W-based heteropoly acids, H3PMo12O40 (MPA) or H3PW12O40 (WPA), with an appropriate ammonium salt such as cetylpyridinium chloride (CPC), under two-phase conditions using chloroform as the solvent (Tables I and II).The tris(cetylpyridinium) 12-tungtophosphate (CWP), +(CH2)15CH3>3(PW12O40)3-, prepared independently from WPA and 3 equiv of CPC, catalyzes the efficient ketonization of the secondary hydroxy group of alcohols and diols with H2O2 under homogeneous conditions using tert-butyl alcohol as the solvent (Table III).Under the same conditions, oxidative cleavage of vic-diols was successfully conducted by the CWP-H2O2 system to give carboxylic acids in good yields (Table IV).This catalyst-oxidant system was also efficient for the oxidative cleavage of carbon-carbon double bonds of olefins which provides a new valuable conversion of olefins to carboxylic acids (Table V).
- Ishii, Yasutaka,Yamawaki, Kazumasa,Ura, Toshikazu,Yamada, Hiroshi,Yoshida, Tsutomu,Ogawa, Masaya
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p. 3587 - 3593
(2007/10/02)
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- Quaternary Ammonium Tetrakis(diperoxotungsto)phosphates(3-) as a New Class of Catalysts for Efficient Alkene Epoxidation with Hydrogen Peroxide
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The use of quaternary ammonium tetrakis(diperoxotungsto)phosphates(3-) in conjuction with hydrogen peroxide as the primary oxidant in an aqueous/organic biphase system provides an efficient, versatile, and synthetically valuable catalytic method for olefin epoxidation.By this method, a variety of water-insoluble unactivated alkenes, internal or terminal, open-chain or cyclic, isolated or carrying diversified functionalities, were epoxidized in high yields under mild conditions and after relatively short reaction times.
- Venturello, Carlo,D'Aloiso, Rino
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p. 1553 - 1557
(2007/10/02)
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- Autoxidation of Vinylcyclopentane, Vinylcyclohexane, and 4-Vinylcyclohex-1-ene
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The title olefins were oxidized with molecular oxygen at 75-80 deg C.About 40percent of the oxygen absorbed were found by iodometric titration as peroxidic oxygen.The reaction products were analyzed by a combination of chemical methods, gas chromatography, and 13C-n.m.r.-spectroscopy.Vinylcyclopentane and vinylcyclohexane are attacked preferably at the tertiary allylic C-H-bonds giving almost equimolar mixtures of the corresponding allylisomeric hydroperoxides.In the case of 4-vinylcyclohex-1-ene the C-H-bonds in position 6 are preferably attacked, but products of attack on the other allylic C-H-bonds also could be identified.In all cases the amount of products which could not be detected gaschromatographically was determined by balance experiments in the presence of an internal standard.
- Biela, R.,Bilas, W.,Ihsan, U.,Pritzkow, W.,Schmidt-Renner, W.
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p. 893 - 900
(2007/10/02)
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