- Chelating alcohols accelerate the samarium diiodide mediated reduction of 3-heptanone
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Initial rate studies of samarium diiodide mediated reduction of 3-heptanone to 3-heptanol are reported. The reduction of 3-heptanone with the polydentate tri(ethylene glycol) methyl ether is 16 times faster than without a proton donor, and 4.3 times faster than methanol. The primary kinetic isotope effect (KIE) was measured as kH/kD ≈ 2, indicating a rate-determining proton transfer. Diols are superior to mono-alcohols as proton donors, the reduction of 3-heptanone is 255 times as fast with di(ethylene glycol) than in the absence of a proton donor. A mechanism of glycol accelerated samarium diiodide reduction is discussed.
- Dahlén, Anders,Hilmersson, G?ran
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Read Online
- Mechanistic Insights into the Aerobic Oxidation of Aldehydes: Evidence of Multiple Reaction Pathways during the Liquid Phase Oxidation of 2-Ethylhexanal
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The liquid-phase aldehyde oxidation by molecular oxygen (autoxidation) has been known for about 2 centuries and is a critical organic transformation in both industrial applications and academic research. However, the general reaction pathway proposed for the aerobic oxidation of aldehydes into the corresponding carboxylic acid exhibits some inconstancies, in particular, for β-substituted aliphatic aldehydes. Thus, the liquid-phase aerobic oxidation of 2-ethylhexanal was further studied in acetonitrile at 20 °C with O2 at atmospheric pressure. By precisely monitoring the primary intermediate (peracid), product (carboxylic acid), and byproducts as a function of time and catalysts used, we demonstrated the pivotal role of the acylperoxy radical. The direct formation of peracid and carboxylic acid from the latter was highlighted by analyzing the composition of the reaction mixture at low conversion. Peracid could be converted into carboxylic acid by metal catalysts or through reaction workup. Consequently, the commonly accepted pathway of aerobic oxidation of aldehyde via a Criegee intermediate can be overlooked under these conditions.
- Vanoye, Laurent,Favre-Réguillon, Alain
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p. 335 - 346
(2022/02/10)
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- Iron(III) Complexation with Galactodendritic Porphyrin Species and Hydrocarbons’ Oxidative Transformations
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The iron metalation of the known free-base porphyrins H2P2 and H2P3, obtained by structural modification of the well-known TPPF20 (H2P1) with galactose dendritic units, gave the corresponding iron(III) porphyrin complex FeP2 and the solid hybrid material FeP3S. Their synthesis, characterization and catalytic efficacy toward the oxidation of the organic substrates (Z)-cyclooctene, cyclohexane and heptane, are reported. In this work, the possibility to modulate selectivity and chemical efficiency of the catalytic system by using simple and more sophisticated metalloporphyrins is demonstrated. Furthermore, the presence of the galactose dendrimer units at the meso-porphyrin ring positions can tune the oxidation at the terminal positions in linear alkanes. In addition, the FeP3S material was easily recovered and reused at least 3 times for the cyclooctene oxidation. The catalytic performance of material FeP3S, associated with their possibility of reuse, makes this material a promising catalyst.
- Castro, Kelly A. D. F.,Westrup, Kátia C. M.,Silva, Sandrina,Pereira, Patrícia M. R.,Sim?es, Mário M. Q.,Neves, Maria da Gra?a P. M. S.,Cavaleiro, José A. S.,Tomé, Jo?o P. C.,Nakagaki, Shirley
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p. 2857 - 2869
(2021/07/14)
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- Robust Mn(iii): N -pyridylporphyrin-based biomimetic catalysts for hydrocarbon oxidations: heterogenization on non-functionalized silica gel versus chloropropyl-functionalized silica gel
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Two classes of heterogenized biomimetic catalysts were prepared and characterized for hydrocarbon oxidations: (1) by covalent anchorage of the three Mn(iii) meso-tetrakis(2-, 3-, or 4-pyridyl)porphyrin isomers by in situ alkylation with chloropropyl-functionalized silica gel (Sil-Cl) to yield Sil-Cl/MnPY (Y = 1, 2, 3) materials, and (2) by electrostatic immobilization of the three Mn(iii) meso-tetrakis(N-methylpyridinium-2, 3, or 4-yl)porphyrin isomers (MnPY, Y = 4, 5, 6) on non-modified silica gel (SiO2) to yield SiO2/MnPY (Y = 4, 5, 6) materials. Silica gel used was of column chromatography grade and Mn porphyrin loadings were deliberately kept at a low level (0.3% w/w). These resulting materials were explored as catalysts for iodosylbenzene (PhIO) oxidation of cyclohexane, n-heptane, and adamantane to yield the corresponding alcohols and ketones; the oxidation of cyclohexanol to cyclohexanone was also investigated. The heterogenized catalysts exhibited higher efficiency and selectivity than the corresponding Mn porphyrins under homogeneous conditions. Recycling studies were consistent with low leaching/destruction of the supported Mn porphyrins. The Sil-Cl/MnPY catalysts were more efficient and more selective than SiO2/MnPY ones; alcohol selectivity may be associated with hydrophobic silica surface modification reminiscent of biological cytochrome P450 oxidations. The use of widespread, column chromatography, amorphous silica yielded Sil-Cl/MnPY or SiO2/MnPY catalysts considerably more efficient than the corresponding, previously reported materials with mesoporous Santa Barbara Amorphous No 15 (SBA-15) silica. Among the materials studied, in situ derivatization of Mn(iii) 2-N-pyridylporphyrin by covalent immobilization on Sil-Cl to yield Sil-Cl/MnP1 showed the best catalytic performance with high stability against oxidative destruction and reusability/recyclability.
- Pinto, Victor Hugo A.,Falc?o, Nathália K. S. M.,Mariz-Silva, Bárbara,Fonseca, Maria Gardennia,Rebou?as, Júlio S.
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supporting information
p. 16404 - 16418
(2020/12/03)
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- Regioselective C-H hydroxylation of: N -alkanes using Shilov-type Pt catalysis in perfluorinated micro-emulsions
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Shilov-chemistry inspired catalysis has remained largely overlooked as a tool for establishing the remote hydroxylation of non-polar compounds, such as long linear alkanes, due to the need for an acidic aqueous solution. To circumvent the solubility issue, the concept of micellar catalysis is introduced, using PtII in perfluorinated micro-emulsions. Notably, the terminal C-H activation of n-heptane is demonstrated under an oxygen atmosphere using perfluorooctanoic acid (PFOA) as a surfactant, along with the intrinsic ability of PtII to convert the highly inert primary C-H bonds. Coordination of PtII to the carboxylate groups of PFOA proved to be particularly important for achieving maximum catalyst activity towards the hydrocarbon substrate solubilized inside the micelle interior. Based on these insights, optimization of the reaction parameters allowed a positional selectivity of 60% for 1-heptanol, among the C7 alcohols, to be achieved, using low catalyst and surfactant loadings under acid-free conditions.
- De Vos, Dirk E.,Janssen, Michiel
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p. 1264 - 1272
(2020/03/23)
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- Metal-Organic Architectures Assembled from Multifunctional Polycarboxylates: Hydrothermal Self-Assembly, Structures, and Catalytic Activity in Alkane Oxidation
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A three-component aqueous reaction system comprising copper(II) acetate (metal node), poly(carboxylic acid) with a phenylpyridine or biphenyl core (main building block), and 1,10-phenanthroline (crystallization mediator) was investigated under hydrothermal conditions. As a result, four new coordination compounds were self-assembled, namely, {[Cu(μ3-cpna)(phen)]·H2O}n (1), {[Cu(μ-Hbtc)(phen)]·H2O}n (2), {[Cu(μ3-Hcpic)(phen)]·2H2O}n (3), and [Cu6(μ-Hcptc)6(phen)6]·6H2O (4), where H2cpna = 5-(2′-carboxylphenyl)nicotinic acid, H3btc = biphenyl-2,4,4′-tricarboxylic acid, H3cpic = 4-(5-carboxypyridin-2-yl)isophthalic acid, H3cptc = 2-(4-carboxypyridin-3-yl)terephthalic acid, and phen = 1,10-phenanthroline. Crystal structures of compounds 1-3 reveal that they are 1D coordination polymers with a ladder, linear, or double-chain structure, while product 4 is a 0D hexanuclear complex. All of the structures are extended further [1D a?' 2D (1 and 2), 1D a?' 3D (3), and 0D a?' 3D (4)] into hydrogen-bonded networks. The type of a multicarboxylate building block has a considerable effect on the final structures of 1-4. The magnetic behavior and thermal stability of 1-4 were also investigated. Besides, these copper(II) derivatives efficiently catalyze the oxidation of cycloalkanes with hydrogen peroxide under mild conditions. The obtained products are the unique examples of copper derivatives that were assembled from H2cpna, H3btc, H3cpic, and H3cptc, thus opening up their use as multicarboxylate ligands toward the design of copper-organic architectures.
- Gu, Jinzhong,Wen, Min,Cai, Yan,Shi, Zifa,Arol, Aliaksandr S.,Kirillova, Marina V.,Kirillov, Alexander M.
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p. 2403 - 2412
(2019/02/28)
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- Heptanuclear Fe5Cu2-Phenylgermsesquioxane containing 2,2′-Bipyridine: Synthesis, Structure, and Catalytic Activity in Oxidation of C-H Compounds
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A new representative of an unusual family of metallagermaniumsesquioxanes, namely the heterometallic cagelike phenylgermsesquioxane (PhGeO2)12Cu2Fe5(O)OH(PhGe)2O5(bipy)2 (2), was synthesized and structurally characterized. Fe(III) ions of the complex are coordinated by oxa ligands: (i) cyclic (PhGeO2)12 and acyclic (Ph2Ge2O5) germoxanolates and (ii) O2- and (iii) HO- moieties. In turn, Cu(II) ions are coordinated by both oxa (germoxanolates) and aza ligands (2,2′-bipyridines). This "hetero-type" of ligation gives in sum an attractive pagoda-like molecular architecture of the complex 2. Product 2 showed a high catalytic activity in the oxidation of alkanes to the corresponding alkyl hydroperoxides (in yields up to 30%) and alcohols (in yields up to 100%) and in the oxidative formation of benzamides from alcohols (catalyst loading down to 0.4 mol % in Cu/Fe).
- Bilyachenko, Alexey N.,Khrustalev, Victor N.,Zubavichus, Yan V.,Shul'Pina, Lidia S.,Kulakova, Alena N.,Bantreil, Xavier,Lamaty, Frédéric,Levitsky, Mikhail M.,Gutsul, Evgeniy I.,Shubina, Elena S.,Shul'Pin, Georgiy B.
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p. 528 - 534
(2018/01/11)
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- New oxidovanadium(iv) complex with a BIAN ligand: synthesis, structure, redox properties and catalytic activity
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Reaction of VCl3 with bis[N-(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) in air afforded [VOCl2(dpp-bian)] (1). The complex was characterized by IR and UV-vis spectroscopies and elemental analysis. The crystal structure of 1 was determined by X-ray diffraction (XRD) analysis. The vanadium atom is in a square-pyramidal OCl2N4 coordination environment. The cyclic voltammogram (CV) in dichloromethane reveals an irreversible oxidation process at +1.40 V (vs. Ag/AgCl) assigned to the V(iv)/V(v) couple, and two consecutive quasi-reversible one-electron reduction processes at ?0.32 V and ?1.05 V (vs. Ag/AgCl), respectively, assigned to the bian/bian?/ and bian?//bian2? couples, followed by irreversible reduction at ?1.6 V (vs. Ag/AgCl). The EPR spectrum of 1 in toluene shows a single 8-line signal typical for oxidovanadium(iv) complexes with d1 configuration. The magnetic behavior of 1 confirms the presence of one unpaired electron (μeff (330 K) = 1.67 μB), and the isolation of the paramagnetic centers. Application of 1 to oxidation of alkanes documented high catalytic activity under mild conditions. The kinetics and selectivity of alkane oxygenation by the 1/H2O2 and 1/PCA/H2O2 systems (PCA is pyrazine-2-carboxylic acid) were studied. The reaction is more efficient in the presence of PCA.
- Fomenko, Iakov S.,Gushchin, Artem L.,Shul'pina, Lidia S.,Ikonnikov, Nikolay S.,Abramov, Pavel A.,Romashev, Nikolay F.,Poryvaev, Artem S.,Sheveleva, Alena M.,Bogomyakov, Artem S.,Shmelev, Nikita Y.,Fedin, Matvey V.,Shul'pin, Georgiy B.,Sokolov, Maxim N.
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supporting information
p. 16200 - 16210
(2018/10/04)
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- Mild and selective reduction of aldehydes utilising sodium dithionite under flow conditions
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We recently reported a novel hybrid batch-flow synthesis of the antipsychotic drug clozapine in which the reduction of a nitroaryl group is described under flow conditions using sodium dithionite. We now report the expansion of this method to include the reduction of aldehydes. The method developed affords yields which are comparable to those under batch conditions, has a reduced reaction time and improved space-time productivity. Furthermore, the approach allows the selective reduction of aldehydes in the presence of ketones and has been demonstrated as a continuous process.
- Neyt, Nicole C.,Riley, Darren L.
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supporting information
p. 1529 - 1536
(2018/07/05)
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- Interplay between H-bonding and interpenetration in an aqueous copper(ii)-aminoalcohol-pyromellitic acid system: self-assembly synthesis, structural features and catalysis
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Two new copper(ii) coordination compounds, [Cu(H1.5mdea)2]2(H2pma) (1a) and [{Cu2(μ-Hmdea)2}2(μ4-pma)]n·2nH2O (1b), were self-assembled at different temperatures from the same multicomponent reaction system, comprising copper(ii) nitrate, N-methyldiethanolamine (H2mdea), pyromellitic acid (H4pma), and potassium hydroxide. Products 1a and 1b were isolated as microcrystalline solids and fully characterized and their structures were established by single-crystal X-ray diffraction. Compound 1a features the bis-aminoalcohol(ate) monocopper(ii) units and H2pma2? anions that are multiply interconnected by strong H-bonds into a firm 2D H-bonded layer. Compound 1b reveals the bis-aminoalcoholate dicopper(ii) motifs that are interlinked by the μ4-pma4? spacers into a 3D + 3D interpenetrated metal-organic framework. From a topological perspective, both networks of 1a and 1b are uninodal and driven by similar 4-connected H2pma2? or pma4? nodes, but result in distinct sql and dia topologies, respectively. Compound 1a was applied as an efficient catalyst for two model cycloalkane functionalization reactions: (1) oxidation by H2O2 to form cyclic alcohols and ketones and (2) hydrocarboxylation by CO/H2O and S2O82? to form cycloalkanecarboxylic acids. The substrate scope, effects of various reaction parameters, selectivity and mechanistic features were also investigated.
- Fernandes, Tiago A.,Kirillova, Marina V.,André, Vania,Kirillov, Alexander M.
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p. 16674 - 16683
(2018/12/05)
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- OPEN-FLASK HYDROBORATION AND THE USE THEREOF
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The present disclosure generally relates to a process for hydroboration of an alkene or alkyne using ammonia borane (AB). In particular, the present invention relates to hydroboration of an alkene or alkyne in the presence of air or moisture, and a clean process for facile preparation of an alcohol by oxidizing the organoborane so formed with hydrogen peroxide. The products, including aminodialkylboranes, ammonia trialkylborane complexes, as well as various alcohols so prepared, are within the scope of this disclosure.
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Paragraph 0046; 0049; 0059; 0060; 0061
(2018/03/25)
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- Synthesis, structures and catalytic activity of p-tolylimido rhenium(V) complexes incorporating quinoline-derived ligands
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p-Tolylimido rhenium(V) complexes, trans-(Cl,Cl)-[Re(p-NC6H4CH3)Cl2(4-MeO-quin-2-COO)(PPh3)] (1), trans-(Br,Br)-[Re(p-NC6H4CH3)Br2(4-MeO-quin-2-COO)(PPh3)]·2MeCN (2), trans-(Cl,Cl)-[Re(p-NC6H4CH3)Cl2(isoquin-1-COO)(PPh3)] (3), trans-(Br,Br)-[Re(p-NC6H4CH3)Br2(isoquin-1-COO)(PPh3)] (4), cis-(Cl,Cl)-[Re(p-NC6H4CH3)Cl2(4-MeO-quin-2-COO)(PPh3)] (5), cis-(Br,Br)-[Re(p-NC6H4CH3)Br2(4-MeO-quin-2-COO)(PPh3)]·MeOH (6), cis-(Cl,Cl)-[Re(p-NC6H4CH3)Cl2(isoquin-1-COO)(PPh3)] (7) and cis-(Br,Br)-[Re(p-NC6H4CH3)Br2(isoquin-1-COO)(PPh3)] (8), have been synthesized and characterized using X-ray analysis and spectroscopic methods (IR,1H,13C and31P NMR, UV–Vis). To elucidate the structural, spectroscopic and bonding properties, the theoretical calculations at the DFT level were undertaken for 1, 3, 5 and 7. The synthesized complexes exhibited moderate activity in the oxidation of 1-phenylethanol and certain alkanes (n-heptane and methylcyclohexane) with tert-butyl hydroperoxide (TBHP) in acetonitrile. Chromatograms of products obtained from the alkanes indicated that a sufficient sterical hindrance exists around of the rhenium catalytic center.
- Gryca,Machura,Shul'pina, Lidia S.,Shul'pin, Georgiy B.
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supporting information
p. 683 - 695
(2016/12/02)
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- Oxidation of Alkanes by Periodate Using a MnV Nitrido Complex as Catalyst
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The design of catalytic systems that can selectively oxidize unactivated C?H bonds under mild conditions is a challenge to chemists. We report here that the manganese(V) nitrido complex [MnV(N)(CN)4]2? is a highly efficient catalyst for the oxidation of alkanes by periodate (IO4 ?) at ambient conditions. Excellent yields of alcohols and ketones (>95 %) are obtained with a maximum turnover number (TON) of 3000.
- Ma, Li,Chen, Lingjing,Lau, Tai-Chu
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p. 2846 - 2848
(2016/10/25)
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- Dinuclear Di(N-heterocyclic carbene) iridium(III) complexes as catalysts in transfer hydrogenation
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Two novel di(N-heterocyclic carbene) complexes of formula (μ-PyrIm-CH2-ImPyr)[IrCp?Cl]2(PF6)2 (1) and μ-MeIm-CH2(p-C6H2)CH2-ImMe[IrCp? Cl]2 (2) (Im = imidazol-2-ylidene) have been synthesised by transmetallation of the dicarbene ligand from the corresponding dicarbene silver complex, using [IrCp?(μ-Cl)Cl]2 as an iridium precursor. The structure of complex 2 has been determined by X-ray diffraction and is characterized by a double ortho-metallation of the p-xylylene bridge between the carbene units. Both complexes show good activity in the transfer hydrogenation of ketones to alcohols in 2-propanol. Dinuclear iridium(III) complexes bearing a bridging di(NHC) ligand have been synthesised and tested as catalysts in transfer hydrogenation reactions.
- Volpe, Andrea,Baldino, Salvatore,Tubaro, Cristina,Baratta, Walter,Basato, Marino,Graiff, Claudia
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p. 247 - 251
(2016/01/20)
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- A non-dissociative open-flask hydroboration with ammonia borane: Ready synthesis of ammonia-trialkylboranes and aminodialkylboranes
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Under open-flask conditions, ammonia borane hydroborates olefins in refluxing tetrahydrofuran. Unlike conventional hydroboration, the Lewis base (ammonia) is not dissociated from the boron center. Terminal alkenes selectively provide ammonia-trialkylborane complexes. On the other hand, internal alkenes afford aminodialkylboranes via a metal-free hydroboration-dehydrogenation sequence. Alkaline hydrogen peroxide oxidation of the products provides the corresponding alcohols in high yields.
- Ramachandran, P. Veeraraghavan,Drolet, Michael P.,Kulkarni, Ameya S.
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supporting information
p. 11897 - 11900
(2016/10/09)
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- ALKANE OXIDATION BY MODIFIED HYDROXYLASES
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This invention relates to modified hydroxylases. The invention further relates to cells expressing such modified hydroxylases and methods of producing hydroxylated alkanes by contacting a suitable substrate with such cells.
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Paragraph 0341
(2016/02/16)
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- Synthesis of new metalloporphyrin derivatives from [5,10,15,20-tetrakis (pentafluorophenyl)porphyrin] and 4-mercaptobenzoic acid for homogeneous and heterogeneous catalysis
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Synthetic metalloporphyrins are catalysts that can efficiently insert oxygen and other atoms such as nitrogen and sulfur in hydrocarbons and in a wide variety of other organic compounds. This work reports on a synthetic strategy to prepare new metalloporphyrins via structural modification of [5,10,15,20-tetrakis (pentafluorophenyl)porphyrin], or [H2(TPFPP)], with 4-mercaptobenzoic acid; it also describes their characterization and catalytic activity. The substituent groups present in the structure of the resulting porphyrins furnished structured solids, which could potentially serve as catalysts in heterogeneous medium. Investigation of the catalytic activity of the new derivatives in the oxidation of (Z)-cyclooctene, cyclohexane, and heptane, under homogeneous conditions, and in the oxidation of (Z)-cyclooctene, in heterogeneous medium, proved that the new metalloporphyrins constituted excellent catalysts for (Z)-cyclooctene epoxidation. As for alkane oxidation, they selectively gave the corresponding alcohol in good yields.
- de F. Castro, Kelly A.D.,Sim?es, Mário M.Q.,da Gra?a P.M.S. Neves, Maria,Cavaleiro, José A.S.,Ribeiro, Ronny R.,Wypych, Fernando,Nakagaki, Shirley
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- Catalytic oxidation of alkanes by a (salen)osmium(VI) nitrido complex using H2O2 as the terminal oxidant
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The osmium(vi) nitrido complex, [OsVI(N)(L)(CH3OH)]+ (1, L = N,N′-bis(salicylidene)-o-cyclohexyldiamine dianion) is an efficient catalyst for the oxidation of alkanes under ambient conditions using H2O2 as the oxidant. Alkanes are oxidized to the corresponding alcohols and ketones, with yields up to 75% and turnover numbers up to 2230. Experimental and computational studies are consistent with a mechanism that involves O-atom transfer from H2O2 to [OsVI(N)(L)]+ to generate an [OsVIII(N)(O)(L)]+ active intermediate.
- Chen, Man,Pan, Yi,Kwong, Hoi-Ki,Zeng, Raymond J.,Lau, Kai-Chung,Lau, Tai-Chu
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supporting information
p. 13686 - 13689
(2015/09/02)
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- Oxidation of alkanes and benzene with hydrogen peroxide catalyzed by ferrocene in the presence of acids This article is dedicated to the memory of Aleksandr Evgenievich Shilov (1930-2014).
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The efficient (turnover numbers attained 1200) oxidation of alkanes to the corresponding alkyl hydroperoxides by H2O2 in the presence of catalytic amounts of ferrocene proceeds in MeCN at 40-50 °C. Benzene is oxidized in the same system to phenol. An obligatory component of the catalytic system for both reactions is pyrazine-2-carboxylic acid (PCA) or trifluoroacetic acid (TFA). Kinetic study as well as selectivity parameters testified that the oxidation proceeds with the participation of hydroxyl radicals. In the case of PCA as a co-catalyst the initial rate W0 of the reaction with both cyclohexane and benzene depends quadratically on [Cp2Fe]0 whereas the two reactions in the presence of TFA are of half order in ferrocene. The ferrocene-catalyzed reaction of cyclohexane with H2O216 in an atmosphere of labeled 18O2 gave after 2 h a mixture of labeled and unlabeled cyclohexyl hydroperoxide (total yield 20% based on starting cyclohexane) containing up to 69% of 18O (the analysis was after reduction of cyclohexyl hydroperoxide into cyclohexanol with PPh3).
- Shul'pina, Lidia S.,Kudinov, Aleksandr R.,Mandelli, Dalmo,Carvalho, Wagner A.,Kozlov, Yuriy N.,Vinogradov, Mikhail M.,Ikonnikov, Nikolay S.,Shul'pin, Georgiy B.
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p. 217 - 231
(2015/09/01)
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- Facile Protocol for Catalytic Frustrated Lewis Pair Hydrogenation and Reductive Deoxygenation of Ketones and Aldehydes
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A series of ketones and aldehydes are reduced in toluene under H2 in the presence of 5 mol % B(C6F5)3 and either cyclodextrin or molecular sieves affording a facile metal-free protocol for reduction to alcohols. Similar treatment of aryl ketones resulted in metal-free deoxygenation yielding aromatic hydrocarbons.
- Mahdi, Tayseer,Stephan, Douglas W.
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supporting information
p. 8511 - 8514
(2015/11/27)
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- Enabling catalytic ketone hydrogenation by frustrated lewis pairs
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Hydrogenation of alkyl and aryl ketones using H2 is catalytically achieved in 18 examples using 5 mol % B(C6F5)3 in an ethereal solvent. In these cases the borane and ether behave as a frustrated Lewis pair to activate H2 and effect the reduction.
- Mahdi, Tayseer,Stephan, Douglas W.
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supporting information
p. 15809 - 15812
(2015/02/19)
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- Highly efficient transfer hydrogenation of aldehydes and ketones using potassium formate over AlO(OH)-entrapped ruthenium catalysts
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Ruthenium encapsulated in an aluminium oxyhydroxide-support was investigated for the transfer hydrogenation of aldehydes and ketones with potassium formate as a sustainable green hydrogen donor. The entrapped ruthenium were narrowly distributed with mean diameters of 1.5-1.8 nm. XPS studies show that the ruthenium was present as Ru0 and Ru3+. The catalysts showed high activity even at low metal loadings of 0.5-2 wt.%. The maximum TOF for benzaldehyde hydrogenation was over 1 wt.% Ru. The reduction of aromatic and aliphatic aldehydes was facile and occurred with 100% yield. In comparison, ketones were less readily reduced although moderate to excellent yields could be obtained after a longer reaction time. No leaching of ruthenium was observed in contrast to a catalyst prepared by wet impregnation. Washing of the used catalyst with water and ethanol effectively removed the deposited bicarbonate co-product and the recycled catalyst maintained its activity up to five runs.
- Gao, Yanxiu,Jaenicke, Stephan,Chuah, Gaik-Khuan
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- Highly efficient alkane oxidation catalyzed by [MnV(N)(CN) 4]2-. Evidence for [MnVII(N)(O)(CN) 4]2- as an active intermediate
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The oxidation of various alkanes catalyzed by [MnV(N)(CN) 4]2- using various terminal oxidants at room temperature has been investigated. Excellent yields of alcohols and ketones (>95%) are obtained using H2O2 as oxidant and CF3CH 2OH as solvent. Good yields (>80%) are also obtained using (NH4)2[Ce(NO3)6] in CF 3CH2OH/H2O. Kinetic isotope effects (KIEs) are determined by using an equimolar mixture of cyclohexane (c-C6H 12) and cyclohexane-d12 (c-C6D12) as substrate. The KIEs are 3.1 ± 0.3 and 3.6 ± 0.2 for oxidation by H2O2 and Ce(IV), respectively. On the other hand, the rate constants for the formation of products using c-C6H12 or c-C6D12 as single substrate are the same. These results are consistent with initial rate-limiting formation of an active intermediate between [Mn(N)(CN)4]2- and H2O2 or CeIV, followed by H-atom abstraction from cyclohexane by the active intermediate. When PhCH2C(CH3)2OOH (MPPH) is used as oxidant for the oxidation of c-C6H12, the major products are c-C6H11OH, c-C6H10O, and PhCH2C(CH3)2OH (MPPOH), suggesting heterolytic cleavage of MPPH to generate a Mn=O intermediate. In the reaction of H2O2 with [Mn(N)(CN)4]2- in CF 3CH2OH, a peak at m/z 628.1 was observed in the electrospray ionization mass spectrometry, which is assigned to the solvated manganese nitrido oxo species, (PPh4)[Mn(N)(O)(CN)4] -·CF3CH2OH. On the basis of the experimental results the proposed mechanism for catalytic alkane oxidation by [MnV(N)(CN)4]2-/ROOH involves initial rate-limiting O-atom transfer from ROOH to [Mn(N)(CN)4]2- to generate a manganese(VII) nitrido oxo active species, [MnVII(N)(O) (CN)4]2-, which then oxidizes alkanes (R'H) via a H-atom abstraction/O-rebound mechanism. The proposed mechanism is also supported by density functional theory calculations.
- Ma, Li,Pan, Yi,Man, Wai-Lun,Kwong, Hoi-Ki,Lam, William W.Y.,Chen, Gui,Lau, Kai-Chung,Lau, Tai-Chu
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p. 7680 - 7687
(2014/06/10)
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- A novel P450-based biocatalyst for the selective production of chiral 2-alkanols
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A P450 monooxygenase from Nocardia farcinica (CYP154A8) catalyses the stereo- and regioselective hydroxylation of n-alkanes, still a challenging task in chemical catalysis. In a biphasic reaction system, the regioselectivity for the C2-position of C7-C9 alkanes was over 90%. The enzyme showed strict S-selectivity for all tested substrates, with enantiomeric excess (ee) of up to 91%. This journal is the Partner Organisations 2014.
- Von Bühler, Clemens J.,Urlacher, Vlada B.
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supporting information
p. 4089 - 4091
(2014/04/03)
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- Highly efficient divanadium(V) pre-catalyst for mild oxidation of liquid and gaseous alkanes
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A new binuclear oxovanadium(V) complex bearing an NO2-donor Schiff base ligand, [{VO(EtO)(EtOH)}2(1κ2O,κN: 2κ2O,κN-L)]·2H2O (H4L = bis(2-hydroxybenzylidene)oxalohydrazonic acid) was prepared and fully characterized by IR, 1H NMR and electronic spectroscopies, elemental analysis and single crystal X-ray diffraction. In the presence of 2-pyrazinecarboxylic acid (PCA) or another acid promoter, this compound acts as a highly efficient pre-catalyst towards the oxidation of gaseous and liquid alkanes by aqueous H2O2 under mild conditions, in aqueous MeCN. Total yields of oxygenates up to 45% and overall turnover numbers up to 7.8 × 103 are achieved.
- Gupta, Samik,Kirillova, Marina V.,Guedes Da Silva, M. Fátima,Pombeiro, Armando J.L.
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- Synthesis of ruthenium (II) complexes containing a dihydroperimidine- derived phosphine ligand and their application in transfer hydrogenation of ketones
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The new ruthenium (II) phosphine complexes (η6-C 6H6)RuCl2[μ- (PPh2CH 2N)2CH2(C10H6)]RuCl 2(η6-C6H6) (1) and RuCl 2(PPh3)[(PPh2CH2N) 2CH2(C10H6)] (2) were synthesized and characterized by 1H NMR, 31P {1H} NMR and elemental analysis. Moreover, the structure of ruthenium (II) phosphine complex 1 was confirmed by X-ray crystallography. With complex 1 as the catalyst, the transfer hydrogenation of ketones reacted well, affording the corresponding alcohols in good yields under mild conditions.
- Fu, Qi,Zhang, Lei,Yi, Tao,Zou, Mingjun,Wang, Xiaoyan,Fu, Haiyan,Li, Ruixiang,Chen, Hua
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- Alkali metal directed assembly of heterometallic Vv/M (M = Na, K, Cs) coordination polymers: Structures, topological analysis, and oxidation catalytic properties
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The reactions of [VO(acac)2] with bis(salicylaldehyde)- oxaloyldihydrazone (H4L) and an alkali metal carbonate M 2CO3 (M = K, Na, Cs), in EtOH/H2O medium upon reflux, resulted in the generation of three new heterometallic VV/M materials, namely the 1D [(VO2)2(μ4-L) {Na2(μ-H2O)2(H2O) 2}]n (1), 2D [{V(μ-O)2}2(μ 4-L){K2(μ-H2O)2(H 2O)2}]n (2), and 3D [{V(μ-O) (μ3-O)}2(μ8-L){Cs2(μ-H 2O)2(H2O)2}]n (3) coordination polymers. They were isolated as air-stable solids and fully characterized by IR, UV-vis, 1H, and 51V NMR spectroscopy, ESI-MS(±), elemental, thermal, and single-crystal X-ray diffraction analyses, the latter showing that 1-3 are constructed from the resembling [(VO2)2(μ4/8-L)]2- blocks assembled by the differently bound aqua-metal [M2(μ-H 2O)2(H2O)2]2+ moieties (M = Na, K, Cs). The main distinctive features of 1-3 arise from the different coordination numbers of Na (5), K (7), and Cs (9) atoms, thus increasing the complexity of the resulting networks from the ladder-like 1D chains in 1 to double 2D layers in 2, and layer-pillared 3D framework in 3. The topological analysis of 2 disclosed a uninodal 4-connected underlying net with a rare kgm [Shubnikov plane net (3.6.3.6)/kagome pattern] topology, while 3 features a trinodal 4,7,8-connected underlying net with an unprecedented topology. Compounds 1-3 also show solubility in water (S25 C ≈ 4-7 mg mL-1) and were applied as efficient precatalysts for the homogeneous oxidation of cyclohexane by aqueous H2O2, under mild conditions (50 C) in MeCN/H2O medium and in the presence of an acid promoter. Total yields (based on substrate) of cyclohexanol and cyclohexanone up to 36% and turnover numbers (TONs) up to 5700 were achieved.
- Gupta, Samik,Kirillova, Marina V.,Guedes Da Silva, M. Fatima C.,Pombeiro, Armando J. L.,Kirillov, Alexander M.
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p. 8601 - 8611
(2013/09/02)
-
- A safe and efficient flow oxidation of aldehydes with O2
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A safe, straightforward, and atom economic approach for the oxidation of aliphatic aldehydes to the corresponding carboxylic acids within a continuous flow reactor is reported. Typically, the reaction is performed at room temperature using 5 bar of oxygen in PFA tubing and does require neither additional catalysts nor radical initiators except for those already contained in the starting materials. In some cases, a catalytic amount of a Mn(II) catalyst is added. Such a flow process may prove to be a valuable alternative to traditionally catalyzed aerobic processes.
- Vanoye, Laurent,Aloui, Asma,Pablos, Mertxe,Philippe, Regis,Percheron, Aurelien,Favre-Reguillon, Alain,De Bellefon, Claude
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supporting information
p. 5978 - 5981
(2014/01/06)
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- A new binuclear oxovanadium(v) complex as a catalyst in combination with pyrazinecarboxylic acid (PCA) for efficient alkane oxygenation by H 2O2
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A new binuclear oxovanadium(v) complex [{VO(OEt)(EtOH)}2L] (1) where H4L is bis(2-hydroxybenzylidene)terephthalohydrazide has been synthesized and fully characterized. The combination of 1 with pyrazine-2-carboxylic acid (PCA; a cocatalyst) affords a catalytic system for the efficient oxidation of saturated hydrocarbons, RH, with hydrogen peroxide and air in acetonitrile solution at 50°C to produce alkyl hydroperoxides, ROOH, as the main primary products. Very high turnover numbers (TONs) have been attained in this reaction: for example, after 2220 min, TON = 44 000 and initial TOF (turnover frequency) = 3300 h-1 per molecule of complex 1. The estimated activation energy of the cyclohexane oxygenation in the presence of 1/PCA is Ea = 16 ± 2 kcal mol-1. This value is identical to that obtained for the cyclohexane oxidation with H 2O2 catalyzed by the (n-Bu4N)[VO 3]/PCA combination (17 ± 2 kcal mol-1). The dependences of initial oxidation rates W0 on the initial concentrations of all components of the reaction mixture have been determined. Based on these kinetic data and on the regio- and bond-selectivity parameters measured in the oxidation of linear and branched alkanes a mechanism of the oxidation has been proposed which includes the generation of hydroxyl radicals in the crucial stage. The Royal Society of Chemistry.
- Sutradhar, Manas,Shvydkiy, Nikita V.,Guedes Da Silva, M. Fátima C.,Kirillova, Marina V.,Kozlov, Yuriy N.,Pombeiro, Armando J. L.,Shul'Pin, Georgiy B.
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p. 11791 - 11803
(2013/09/02)
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- Cationic and anionic metalloporphyrins simultaneously immobilized onto raw halloysite nanoscrolls catalyze oxidation reactions
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We simultaneously immobilized an anionic iron(III) porphyrin (FePor) and a cationic manganese(III) porphyrin (MnPor) onto raw halloysite nanoscrolls. The positive and negative residual charges at the edges of the halloysite nanoscrolls and the negative residual charges on the surface of this support favored FePor and MnPor immobilization. We characterized the material containing simultaneously immobilized FePor and MnPor (FeMn-Hallo) by powder X-ray diffraction, Fourier transform infrared spectroscopy, textural analysis, and UV-vis spectroscopy (solid sample); these techniques confirmed that both FePor and MnPor were present on the support. We also investigated whether FeMn-Hallo catalyzed cyclooctene epoxidation as well as cyclohexane and n-heptane oxidation. FeMn-Hallo was an effective catalyst for oxidation reaction, attesting the efficiency and versatility of both immobilized metalloporphyrins in the same support. The simultaneous immobilization of metalloporphyrins paves the way for chemists to develop multifunctional catalysts that can simultaneously promote distinct reactions.
- Machado, Guilherme Sippel,Ucoski, Geani Maria,Lima, Omar José De,Ciuffi, Kátia Jorge,Wypych, Fernando,Nakagaki, Shirley
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p. 124 - 131
(2013/07/27)
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- Hydrogenation and redox isomerization of allylic alcohols catalyzed by a new water-soluble Pd-tetrahydrosalen complex
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For applications in aqueous media, sulfonated tetrahydrosalen (sulfosalan, HSS) was synthesized by sulfonation of tetrahydrosalen in fuming sulfuric acid. The Pd(II) complex of this ligand, [Pd(HSS)], showed outstanding activity in hydrogenation and redox isomerization of allylic alcohols in homogeneous aqueous solutions or in aqueous-organic biphasic systems (for oct-1-en-3-ol TOF(hydrogenation) = 1580 h-1, TOF(redox isomerization) = 400 h -1). DFT calculations revealed that H2 is activated heterolytically, resulting in a Pd(II)-hydride complex, [Pd(H)(HSS-Hphen)], in which one of the phenolate oxygens is protonated. Both hydrogenation and redox isomerization take place via concerted transfer of a proton and a hydride from the hydrogenated catalyst to the allylic alcohol.
- Voronova, Krisztina,Purgel, Mihaly,Udvardy, Antal,Benyei, Attila C.,Katho, Agnes,Joo, Ferenc
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p. 4391 - 4401
(2013/09/02)
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- Synthesis of [RuX(CO)(dppp)(NN)]Cl (X = H, Cl; NN = en, ampy) complexes and their use as catalysts for transfer hydrogenation
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The monocarbonyl hydride complexes [RuH(CO)(dppp)(NN)]Cl (dppp = Ph 2P(CH2)3PPh2; NN = ethylenediamine (en), 1; NN = 2-aminomethylpyridine (ampy), 3) have been isolated in high yield by reaction of RuHCl(CO)(PPh3)(dppp) with en and ampy, respectively, in toluene at reflux. The chloride complexes [RuCl(CO)(dppp)(NN)]Cl (NN = en, 2; NN = ampy, 4) have been obtained quantitatively by dissolution of 1 in CH 2Cl2 and 3 in CHCl3, through substitution of the hydride with a chloride and isomerization. Treatment of 4 with NaOiPr in 2-propanol at room temperature cleanly leads to the hydride complex 3. Complexes 1-4 have been proven to be robust and productive catalysts for the transfer hydrogenation of alkyl aryl, diaryl, dialkyl, and cyclic ketones using 0.2-0.004 mol % of catalyst and in the presence of 2 mol % of NaOiPr, affording TOF values up to 2.5 × 105 h-1.
- Zhang, Shuanming,Baldino, Salvatore,Baratta, Walter
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p. 5299 - 5304
(2013/11/06)
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- A heterogenized vanadium oxo-aroylhydrazone catalyst for efficient and selective oxidation of hydrocarbons with hydrogen peroxide
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A hydrazone Schiff base ligand derived from salicylaldehyde and benzhydrazide has been synthesized and reacted with vanadium(IV) leading to the corresponding vanadium(V) complex. The complex has been anchored on the surface of functionalized silica gel by N,O-coordination to the covalently Si-O bound modified salicylaldiminato ligand. The supported complex has been evaluated as a catalyst for hydrocarbon oxidation with hydrogen peroxide in acetonitrile. The heterogeneous system proved to be an efficient catalyst and was able to activate hydrogen peroxide toward the oxidation of alkenes, alkanes, benzene, and alkylaromatic compounds with more than 2,500 h-1 activity. Springer Science+Business Media B.V. 2011.
- Monfared, Hassan Hosseini,Abbasi, Vahideh,Rezaei, Adineh,Ghorbanloo, Massomeh,Aghaei, Alireza
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experimental part
p. 85 - 92
(2012/08/28)
-
- Syntheses of enantiopure aliphatic secondary alcohols and acetates by bioresolution with lipase B from candida antarctica
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The lipase B from Candida antarctica (Novozym 435, CALB) efficiently catalyzed the kinetic resolution of some aliphatic secondary alcohols: (±)-4-methylpentan- 2-ol (1), (±)-5-methylhexan-2-ol (3), (±)-octan-2-ol (4), (±)-heptan-3-ol (5) and (±)-oct-1- en-3-ol (6). The lipase showed excellent enantioselectivities in the transesterifications of racemic aliphatic secondary alcohols producing the enantiopure alcohols (>99% ee) and acetates (>99% ee) with good yields. Kinetic resolution of rac-alcohols was successfully achieved with CALB lipase using simple conditions, vinyl acetate as acylating agent, and hexane as non-polar solvent.
- Ferreira, Hercules V.,Rocha, Lenilson C.,Severino, Richele P.,Porto, Andre L. M.
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p. 8955 - 8967,13
(2020/08/31)
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- Transfer hydrogenation of ketones by ceria-supported Ni catalysts
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Ni-loaded CeO2, prepared by H2-reduction of NiO-loaded CeO2, was found to be an effective and recyclable catalyst for the transfer hydrogenation of aliphatic and aromatic ketones by 2-propanol to the corresponding alcohols under base free conditions with low catalyst loading (1-3 mol%).
- Shimura, Katsuya,Shimizu, Ken-Ichi
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supporting information
p. 2983 - 2985
(2013/01/15)
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- Ni/Pd@MIL-101: Synergistic catalysis with cavity-conform Ni/Pd Nanoparticles
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A perfect fit: Cavity-conform bimetallic Ni/Pd nanoparticles of different composition were generated in the metal-organic framework MIL-101. Experimental evidence and molecular dynamic simulations indicate the existence of mixed bimetallic particles. Pronounced synergistic effects have been observed in liquid-phase catalysis. Copyright
- Hermannsdoerfer, Justus,Friedrich, Martin,Miyajima, Nobuyoshi,Albuquerque, Rodrigo Q.,Kuemmel, Stephan,Kempe, Rhett
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p. 11473 - 11477
(2013/01/15)
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- Anionic iron(III) porphyrins immobilized on zinc hydroxide chloride as catalysts for heterogeneous oxidation reactions
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This work describes the immobilization of an anionic iron(III) porphyrin (FePor) family on zinc hydroxide chloride (ZHC), a layered hydroxide salt prepared by reacting an aqueous zinc chloride solution with an ammonium hydroxide solution. The FePor immobilization was performed at room temperature under magnetic stirring, under air atmosphere, of each complex ethanol solution and the ZHC solid support suspension. The materials obtained were characterized by X-ray powder diffraction (XRPD), ultraviolet-visible spectroscopy (UV-vis) (solid samples), Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance (EPR). The catalytic activity of the solids was investigated in cyclooctene, cyclohexane and n-heptane heterogeneous catalytic oxidation reactions with iodosylbenzene as the oxygen donor. The solid catalyst's reutilization capacity was also investigated and the heterogeneous character of the catalytic process was confirmed. The compounds and the catalytic activity of FePor-ZHC were compared with the synthesis and catalytic activity of the same FePor immobilized on zinc hydroxide nitrate (ZHN). Though the matrixes are similar, the results obtained were exactly the opposite when the selectivity was analyzed.
- MacHado, Guilherme Sippel,Wypych, Fernando,Nakagaki, Shirley
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experimental part
p. 94 - 102
(2012/03/27)
-
- A family of novel cationic ruthenium pincer complexes: Synthesis, characterization and catalytic activity in the transfer hydrogenation of ketones
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A family of novel cationic ruthenium complexes [RuHL(PAr3) 2]Cl (Ar = phenyl, p-methoxyphenyl, and p-trifluoromethylphenyl; L = 2,6-bis(1,5-diphenyl-1H-pyrazol-3-yl)pyridine) has been synthesized and characterized by IR, 31P{1H} NMR, 1H NMR and elemental analyses. The [RuHL(PPh3)2]Cl was further identified by X-ray crystallography. These complexes exhibit good to excellent catalytic activities for the transfer hydrogenation of ketones in refluxing 2-propanol, and the highest TOF is up to 3534 h- 1. The effect of electronic factors of these complexes on the transfer hydrogenation of ketones reveals that the catalytic activity is promoted by the electron-withdrawing phosphine.
- Wang, Lei,Pan, Hai-Ran,Yang, Qin,Fu, Hai-Yan,Chen, Hua,Li, Rui-Xiang
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scheme or table
p. 1422 - 1427
(2011/10/02)
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- Ru-η6-benzene-phosphine complex-catalyzed transfer hydrogenation of ketones
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Three Ru-η6-benzene-phosphine complexes bearing tri-(p-methoxyphenyl)phosphine, triphenylphosphine and tri-(p- trifluoromethylphenyl)phosphine were synthesized and characterized by 31P{1H} NMR, 1H NMR, 13C{ 1H} NMR and elemental analyses. Complex 1 was further identified by X-ray crystallography. These complexes exhibit good to excellent activities for the transfer hydrogenation of ketones in refluxing 2-propanol, and the highest turnover frequency (TOF) is up to 5940 h-1. The effect of electronic factors of these complexes on the transfer hydrogenation of ketones reveals that the catalytic activity is promoted by electron-donating phosphine and the catalyst stability is improved by electron-withdrawing phosphine.
- Wang, Lei,Yang, Qin,Fu, Hai-Yan,Chen, Hua,Yuan, Mao-Lin,Li, Rui-Xiang
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experimental part
p. 626 - 631
(2011/10/18)
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- A novel cationic dinuclear ruthenium complex: Synthesis, characterization and catalytic activity in the transfer hydrogenation of ketones
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A novel cationic dinuclear ruthenium complex [RuCl(HL)(TFTPP)]2 (H2L = 2,6-bis(5-phenyl-1H-pyrazol-3-yl)pyridine; TFTPP = tri(p-trifluoromethylphenyl)phosphine) has been synthesized and characterized by 31P{1H} NMR, 1H NMR, elemental analysis and X-ray crystallography. This complex is the first cationic dinuclear ruthenium complex bearing N4 ligand characterized by single crystal X-ray analysis. It exhibits good catalytic activity for the transfer hydrogenation of ketones in refluxing 2-propanol.
- Wang, Lei,Yang, Qin,Chen, Hua,Li, Rui-Xiang
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experimental part
p. 1884 - 1888
(2012/02/03)
-
- Silica aerogel-iron oxide nanocomposites: Recoverable catalysts for the oxidation of alcohols with hydrogen peroxide
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Various aerogels of silica gel doped with Fe2O3 were prepared by sol-gel method. They were calcined to produce nanoparticle solids. The nanosized mixed oxides were active in the oxidation of alcohols and produced carbonyl compounds in very good to excellent yields using hydrogen peroxide.
- Masoudian, Shahla,Hosseini Monfared, Hassan,Aghaei, Alireza
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experimental part
p. 521 - 530
(2012/04/17)
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- Mild homogeneous oxidation of alkanes and alcohols including glycerol with tert-butyl hydroperoxide catalyzed by a tetracopper(II) complex
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The homogeneous catalytic system composed of the aqua-soluble tetracopper(II) triethanolaminate complex [O?Cu4{N(CH2CH2O)3}4(BOH)4][BF4]2 (1), t-BuOOH (TBHP), water and acetonitrile solvent (optional) has been applied for the mild oxidation of (i) linear and cyclic alkanes to the corresponding alkyl peroxides, alcohols and ketones, (ii) secondary or primary alcohols to ketones or aldehydes, respectively and (iii) glycerol (GLY) to dihydroxyacetone (DHA). Unusual regio-, bond and stereoselectivity parameters have been determined for the alkane oxygenations and discussed in terms of possible steric, hydrophobic and electronic effects. In alcohol oxidations, secondary alcohols are the most reactive substrates. Yields and TONs up to 82% and 1200, respectively, have been obtained in the oxidation of isopropanol to acetone. The selective oxidation of GLY to DHA by the 1/TBHP system has been also achieved, although providing lower conversions. The 1/H2O2 system for the GLY oxidation is particularly advantageous in terms of selectivity and oxidant efficiency. These systems constitute one of the first examples of a metal-catalyzed oxidation of glycerol under homogeneous conditions.
- Kirillova, Marina V.,Kirillov, Alexander M.,Mandelli, Dalmo,Carvalho, Wagner A.,Pombeiro, Armando J.L.,Shul'Pin, Georgiy B.
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scheme or table
p. 9 - 17
(2010/09/09)
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- Catalytic ionic hydrogenation of ketones by {[Cp*Ru(CO) 2]2(μ-H)}+
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{[Cp*Ru(CO)2]2(μ-H)}OTf functions as a homogeneous catalyst precursor for hydrogenation of ketones to alcohols, with hydrogenations at 1 mol % catalyst loading at 90 °C under H2 (820 psi) proceeding to completion and providing > 90% yields. Hydrogenation of methyl levulinate generates y-valerolactone, presumably by ring-closing of the initially formed alcohol with the methyl ester. Experiments in neat Et2C=O show that the catalyst loading can be 2(η2- H2)]OTf being formed under the reaction conditions from reaction of H2 with [[Cp*Ru(CO)2] 2(μ-H)+OTf.
- Fagan, Paul J.,Voges, Mark H.,Morris Bullock
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experimental part
p. 1045 - 1048
(2010/04/25)
-
- Immobilization of anionic metalloporphyrins on zinc hydroxide nitrate and study of an unusual catalytic activity
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This paper is the first report on the immobilization of an anionic iron(III) porphyrin family on zinc hydroxide nitrate (ZHN), a layered hydroxide salt. ZNH was prepared by means of a precipitation reaction between a zinc nitrate solution and ammonium hydroxide. Two immobilization systems were investigated, namely magnetic stirring at room temperature and stirring/reflux in an ethanolic solution. The solids were characterized by powder X-ray diffraction (XRD), electron paramagnetic resonance (EPR), thermogravimetric and derivative thermogravimetric (TGA/DTG), transmission electron microscopy (TEM), as well as ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopic analyses. The catalytic activity of the materials was investigated in the oxidation of cyclooctene, cyclohexane, and n-heptane using iodosylbenzene as oxygen donor. The oxidation products were analyzed by gas chromatography. The results revealed an unusual selectivity for cyclohexanone in the reactions of cyclohexane oxidation catalyzed by the anionic iron(III) porphyrins immobilized onto ZHN. These results suggest that the structure of the ZHN support influences the catalytic mechanism and that cyclohexane oxidation occurs via a radicalar pathway.
- MacHado, Guilherme S.,Arizaga, Gregorio G.C.,Wypych, Fernando,Nakagaki, Shirley
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experimental part
p. 130 - 141
(2011/01/08)
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- New oxidation catalysts based on iron(III) porphyrins immobilized on Mg-Al layered double hydroxides modified with triethanolamine
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An Mg-Al layered double hydroxide containing intercalated NO 3- anions (LDH-N) was synthesized and subsequently submitted to a reaction with triethanolamine as modifying agent (LDH-TEA). A neutral iron(III) porphyrin was immobilized onto both solids LDH-N and LDH-TEA, and the catalytic activity of the resulting FePor-LDH-N and FePor-LDH-TEA was evaluated in the oxidation of (Z)-cyclooctene, cyclohexane, and heptane using iodosylbenzene as oxidant. Characterization of FePor-LDH-N and FePor-LDH-TEA by UV-vis, FTIR, XRD, XPS, EPR, TGA/DTA, and SEM was also accomplished. The products from the catalytic reactions were analyzed by GC, using an FID detector. The catalytic activity of FePor-LDH-TEA in the oxidation of cyclohexane was around 5 times higher than that obtained with FePor-LDH-N, which does not contain the modifying agent. Moreover, the FePor-LDH-TEA solid displayed significant selectivity in the oxidation of heptane, a substrate that is difficult to oxidize; in fact, a total product yield over 30.0% was achieved. Finally, the performance of the FePor-LDH-TEA catalyst can be attributed to the higher FePor load in this solid, which is 3 times larger compared with FePor-LDH-N. A proposal concerning the mode of FePor immobilization onto the modified LDH is suggested.
- Castro, Kelly Aparecida Dias De Freitas,Bail, Alesandro,Groszewicz, Pedro Braga,MacHado, Guilherme Sippel,Schreiner, Wido Herwig,Wypych, Fernando,Nakagaki, Shirley
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experimental part
p. 51 - 59
(2011/01/03)
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- Coordination compounds from the planar tridentate schiff-base ligand 2-methoxy-6-((quinolin-8-ylimino)methyl)phenol (mqmpH) with several transition metal ions: Use of [FeIII(mqmp)(CH3OH)Cl2] in the catalytic oxidation of alkanes and alkenes
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Four coordination compounds were synthesized in high yields from different transition metal ions (FeIII, CoII, and CuII) and an in situ generated Schiff-base ligand, i.e. 2-methoxy-6-((quinolin-8- ylimino) methyl)phenol (mqmpH). The compounds were characterized by single-crystal X-ray diffraction, ESIMS, IR spectroscopy, and ligand-field spectroscopy. The iron(III) complex is an efficient catalyst for the oxidation of alkanes and alkenes, under relatively mild conditions and with dihydrogen peroxide as terminal oxidant.
- Nayak, Sanjit,Gamez, Patrick,Kozlev?ar, Bojan,Pevec, Andrej,Roubeau, Olivier,Dehnen, Stefanie,Reedijk, Jan
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experimental part
p. 2291 - 2296
(2010/09/06)
-
- Alkane oxidation by the H2O2-NaVO3-H2SO4 system in acetonitrile and water
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A simple system is described, which oxidizes saturated hydrocarbons either in acetonitrile or (less efficiently) in water. The system consists of 50% aqueous hydrogen peroxide as an oxidant, sodium metavanadate, NaVO3, as a catalyst and sulfuric (or oxalic) acid as a co-catalyst. The reactions were carried out at 20-50 °C. In the oxidation of cyclohexane in acetonitrile, the highest yield (37% based on cyclohexane) and turnover number (TON=1700) were attained after 3 h at 50 °C. The corresponding parameters were 16% and 1090 for n-heptane oxidation under the same conditions. The oxidation of higher alkanes, RH, in acetonitrile gives almost exclusively the corresponding alkyl hydroperoxides, ROOH. Light alkanes (n-butane, propane, ethane, and methane) have been also oxygenated by the system under consideration. The highest TON (200) was attained for ethane and the highest yield (19%) was obtained in the case of n-butane. The selectivity parameters measured for the oxidation of linear and branched alkanes are low, the reaction with cis- and trans-1,2-dimethylcyclohexanes is not stereoselective. These facts lead us to conclude that the oxidation occurs with the formation of hydroxyl radicals in the crucial step.
- Shul'pina, Lidia S.,Kirillova, Marina V.,Pombeiro, Armando J.L.,Shul'pin, Georgiy B.
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experimental part
p. 2424 - 2429
(2009/07/25)
-
- Ruthenium-catalyzed redox isomerization/transfer hydrogenation in organic and aqueous media: A one-pot tandem process for the reduction of allylic alcohols
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The hexamethylbenzene-ruthenium(ii) dimer [{RuCl(μ-Cl) (η6-C6Me6)}2] 1 and the mononuclear bis(allyl)-ruthenium(iv) complex [RuCl2(η 3:η2:η3-C12H 18)]2, associated with base and a hydrogen donor, were found to be active catalysts for the selective reduction of the CC bond of allylic alcohols both in organic and aqueous media. The process, which proceeds in a one-pot manner, involves a sequence of two independent reactions: (i) the initial redox-isomerization of the allylic alcohol, and (ii) subsequent transfer hydrogenation of the resulting carbonyl compound. The highly efficient transformation reported herein represents, not only an illustrative example of auto-tandem catalysis, but also an appealing alternative to the classical transition-metal catalyzed CC hydrogenations of allylic alcohols. The process has been successfully applied to aromatic as well as aliphatic substrates affording the corresponding saturated alcohols in 45-100% yields after 1.5-24 h. The best performances were reached using (i) 1-5 mol% of 1 or 2, 2-10 mol% of Cs2CO3, and propan-2-ol or (ii) 1-5 mol% of 1 or 2, 10-15 equivalents of NaO2CH, and water. The catalytic efficiency is strongly related to the structure of the allylic alcohol employed. Thus, in propan-2-ol, the reaction rate essentially depends on the steric requirement around the CC bond, therefore decreasing with the increasing number of substituents. On other hand, in water the transformation is favoured for primary allylic alcohols vs. secondary ones.
- Cadierno, Victorio,Crochet, Pascale,Francos, Javier,Garcia-Garrido, Sergio E.,Gimeno, Jose,Nebra, Noel
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scheme or table
p. 1992 - 2000
(2010/06/19)
-
- Efficient catalytic oxidation of alkanes by lewis acid/[Os VI(N)Cl4]- using peroxides as terminal oxidants. Evidence for a metal-based active intermediate
-
The oxidation of alkanes by various peroxides (tBuOOH, H 2O2, PhCH2C(CH3)2OOH) is efficiently catalyzed by [OsVI(N)Cl4]-/Lewis acid (FeCl3 or Sc(OTf)3) in CH2Cl 2/CH3CO2H to give alcohols and ketones. Oxidations occur rapidly at ambient conditions, and excellent yields and turnover numbers of over 7500 and 1000 can be achieved in the oxidation of cyclohexane with tBuOOH and H2O2, respectively. In particular, this catalytic system can utilize PhCH2C(CH 3)2OOH (MPPH) efficiently as the terminal oxidant; good yields of cyclohexanol and cyclohexanone (>70%) and MPPOH (>90%) are obtained in the oxidation of cyclohexane. This suggests that the mechanism does not involve alkoxy radicals derived from homolytic cleavage of MPPH but is consistent with heterolytic cleavage of MPPH to produce a metal-based active intermediate. The following evidence also shows that no free alkyl radicals are produced in the catalytic oxidation of alkanes: (1) The product yields and distributions are only slightly affected by the presence of O2. (2) Addition of BrCCl3 does not affect the yields of cyclohexanol and cyclohexanone in the oxidation of cyclohexane. (3) A complete retention of stereochemistry occurs in the hydroxylation of cis- and trans-1,2- dimethylcyclohexane. The proposed mechanism involves initial O-atom transfer from ROOH to [OsVI(N)Cl4]-/Lewis acid to generate [OsVIII(N)(O)Cl4]-/Lewis acid, which then oxidizes alkanes via H-atom abstraction.
- Yiu, Shek-Man,Man, Wai-Lun,Lau, Tai-Chu
-
scheme or table
p. 10821 - 10827
(2009/02/05)
-
- Hydroperoxidation of alkanes with hydrogen peroxide catalyzed by aluminium nitrate in acetonitrile
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The first example of alkane oxygenation with hydrogen peroxide catalyzed by a non-transition metal derivative (aluminium) is reported. Heating (70 °C) a solution of an alkane, RH, hydrogen peroxide (70% aqueous) and a catalytic amount of Al(NO3)3·9H2O in air for a few hours afforded the corresponding alkyl hydroperoxide, ROOH. With cyclooctane, the hydroperoxide yield attained 31% and the maximum turnover number was 150. It is proposed on the basis of measurements of the selectivity parameters for the oxidation of linear and branched alkanes and a kinetic study that the oxidation occurs with the participation of hydroxyl radicals.
- Mandelli, Dalmo,Chiacchio, Karyna C.,Kozlov, Yuriy N.,Shul'pin, Georgiy B.
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scheme or table
p. 6693 - 6697
(2009/04/07)
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- Transfer hydrogenation of ketones with 2-propanol and Raney nickel
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Raney nickel in refluxing 2-propanol containing a trace of HCl is an effective catalytic system for the reduction of ketones to secondary alcohols. Copyright Taylor & Francis Group, LLC.
- Mebane, Robert C.,Holte, Kimberly L.,Gross, Benjamin H.
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p. 2787 - 2791
(2008/02/12)
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