- Oxygen Atom Transfer Mechanism for Vanadium-Oxo Porphyrin Complexes Mediated Aerobic Olefin Epoxidation
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The development of catalytic aerobic epoxidation by numerous metal complexes in the presence of aldehyde as a sacrificial reductant (Mukaiyama epoxidation) has been reported, however, comprehensive examination of oxygen atom transfer mechanism involving free radical and highly reactive intermediates has yet to be presented. Herein, meso-tetrakis(pentafluorophenyl) porphyrinatooxidovanadium(IV) (VOTPFPP) was prepared and proved to be efficient toward aerobic olefin epoxidation in the presence of isobutyraldehyde. In situ electron paramagnetic resonance spectroscopy (in situ EPR) showed the generation, transfer pathways and ascription of free radicals in the epoxidation. According to the spectral and computational studies, the side-on vanadium-peroxo complexes are considered as the active intermediate species in the reaction process. In the cyclohexene epoxidation catalyzed by VOTPFPP, the kinetic isotope effect value of 1.0 was obtained, indicating that epoxidation occurred via oxygen atom transfer mechanism. The mechanism was further elucidated using isotopically labeled dioxygen experiments and density functional theory (DFT) calculations.
- Han, Qi,Huang, Jia-Ying,Ji, Hong-Bing,Liu, Xiao-Hui,Tao, Lei-Ming,Xue, Can,Yu, Hai-Yang,Zhou, Xian-Tai,Zou, Wen
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supporting information
p. 115 - 122
(2021/12/04)
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- Liquid-phase oxidation of olefins with rare hydronium ion salt of dinuclear dioxido-vanadium(V) complexes and comparative catalytic studies with analogous copper complexes
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Homogeneous liquid-phase oxidation of a number of aromatic and aliphatic olefins was examined using dinuclear anionic vanadium dioxido complexes [(VO2)2(salLH)]? (1) and [(VO2)2(NsalLH)]? (2) and dinuclear copper complexes [(CuCl)2(salLH)]? (3) and [(CuCl)2(NsalLH)]? (4) (reaction of carbohydrazide with salicylaldehyde and 4-diethylamino salicylaldehyde afforded Schiff-base ligands [salLH4] and [NsalLH4], respectively). Anionic vanadium and copper complexes 1, 2, 3, and 4 were isolated in the form of their hydronium ion salt, which is rare. The molecular structure of the hydronium ion salt of anionic dinuclear vanadium dioxido complex [(VO2)2(salLH)]? (1) was established through single-crystal X-ray analysis. The chemical and structural properties were studied using Fourier transform infrared (FT-IR), ultraviolet–visible (UV–Vis), 1H and 13C nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), electron paramagnetic resonance (EPR) spectroscopy, and thermogravimetric analysis (TGA). In the presence of hydrogen peroxide, both dinuclear vanadium dioxido complexes were applied for the oxidation of a series of aromatic and aliphatic alkenes. High catalytic activity and efficiency were achieved using catalysts 1 and 2 in the oxidation of olefins. Alkenes with electron-donating groups make the oxidation processes easy. Thus, in general, aromatic olefins show better substrate conversion in comparison to the aliphatic olefins. Under optimized reaction conditions, both copper catalysts 3 and 4 fail to compete with the activity shown by their vanadium counterparts. Irrespective of olefins, metal (vanadium or copper) complexes of the ligand [salLH4] (I) show better substrate conversion(%) compared with the metal complexes of the ligand [NsalLH4] (II).
- Maurya, Abhishek,Haldar, Chanchal
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- Kinetic investigation of aerobic epoxidation of limonene over cobalt substituted mesoporous SBA-16
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Incorporation of low coordination Co2+within the structure of mesoporous silica SBA-16 has been accomplished through a facile and green “pH adjusting” method. The resulting materials were used as heterogeneous catalysts for aerobic Mukaiyama epoxidation of limonene in the presence of isobutyraldehyde, under very mild conditions. The structural integrity during the pH adjustment procedure at various loadings and states of cobalt ions within the mesoporous structure were determined using characterization techniques including nitrogen physisorption, X-ray fluorescence, diffuse reflectance UV-vis, scanning electron microscopy, temperature-programmed reduction, X-ray photoelectron spectroscopy and powder X-ray diffraction. These catalysts showed quite high reactivity for the epoxidation of limonene with high epoxide yields under optimized oxygen pressure. In this work, a thorough kinetic analysis of aerobic epoxidation of limonene was investigated to allow proposing a reaction scheme. A new mechanism, in which a surface reaction between a Co3+OO?peroxo intermediate and limonene was found to be involved in the formation of the epoxidized limonene. The kinetics developed from the proposed mechanism was accurately fitted with extensive experimental initial reaction rate data. The activation energy for limonene mono epoxide formation was determined to be 22 kJ mol?1
- Madadi, Sara,Bergeron, Jean-Yves,Kaliaguine, Serge
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p. 594 - 611
(2021/02/09)
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- A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles
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A new heterogeneous catalytic system consisting of cobalt nanoparticles (CoNPs) supported on MgO and tert-butyl hydroperoxide (TBHP) as oxidant is presented. This CoNPs@MgO/t-BuOOH catalytic combination allowed the epoxidation of a variety of olefins with good to excellent yield and high selectivity. The catalyst preparation is simple and straightforward from commercially available starting materials and it could be recovered and reused maintaining its unaltered high activity.
- Rossi-Fernández, Lucía,Dorn, Viviana,Radivoy, Gabriel
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supporting information
p. 519 - 526
(2021/03/31)
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- New heptacoordinate tungsten(II) complexes with α-diimine ligands in the catalytic oxidation of multifunctional olefins
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New tungsten(II) and molybdenum(II) heptacoordinate complexes [MX2(CO)3(LY)] (MXLy: M = W, Mo; X = Br, I; LY = C5H4NCY = N(CH2)2CH3 with Y = H (L1), Me (L2), Ph (L3)) were synthesized and characterized by spectroscopic techniques and elemental analysis. The two tungsten complexes WXL1 (X = Br, I) were also structurally characterized by single crystal X-ray diffraction. The metal coordination environment is in both a distorted capped octahedron. The complexes with L1 and L2 ligands were grafted in MCM-41, after functionalization of the ligands with a Si(OEt)3 group. The new materials were characterized by elemental analysis, N2 adsorption isotherms, 29Si MAS and 13C MAS NMR. The tungsten(II) complexes and materials were the first examples of this type reported. All complexes and materials were tested as homogeneous and heterogeneous catalysts in the oxidation of multifunctional olefins (cis-hex-3-en-1-ol, trans-hex-3-en-1-ol, geraniol, S-limonene, and 1-octene), with tert-butyl hydroperoxide (TBHP) as oxidant. The molybdenum(II) catalyst precursors are in general very active, reaching 99% conversion and 100% selectivity in the epoxidation of trans-hex-3-en-1-ol. Their performance is comparable with that of the [Mo(η3-C3H5)X(CO)2(LY)] complexes, but it increases with immobilization. On the other hand, most of the W(II) complexes display an activity similar or inferior to that of the Mo(II) analogues and it decreases after they are supported in MCM-41. DFT calculations show that tungsten complexes and iodide ligands are more easily oxidized from M(II) to M(VI) than molybdenum ones, while the energies of relevant species in the catalytic cycle are very similar for all complexes, making the theoretical rationalization of experimental catalytic data difficult.
- Vasconcellos-Dias, Maria,Nunes, Carla D.,Félix, Vítor,Brand?o, Paula,Calhorda, Maria José
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- Anchoring of a terpyridine-based Mo(VI) complex on manganese ferrite as a recoverable catalyst for epoxidation of olefins under solvent-free conditions
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A magnetically separable heterogeneous nanocatalyst was obtained by anchoring a terpyridine-based Mo(VI) complex on modified MnFe2O4 nanoparticles and characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and diffuse reflectance spectroscopies (DRS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) analysis. The catalytic activity of the supported molybdenum based catalyst was evaluated in the selective epoxidation of various olefins (cyclooctene, limonene, 1-dodecane, 1-heptene, styrene, 1-indene, α-pinene, cyclohexene) with tert-butyl hydroperoxide (TBHP) as an oxidant under solvent-free conditions. This nanocatalyst was easily separated by using an external magnetic field and reused consecutively at least five times with no significant loss in selectivity and catalytic activity. The short reaction time, simple preparation, high conversion, good physicochemical stability and magnetic recycling of the catalysts are beneficial.
- Fadaei Sarabi, Mahsa,Bezaatpour, Abolfazl,Mahmoudi, Ali
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p. 1597 - 1612
(2021/03/29)
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- Heterogeneous catalysis with an organic-inorganic hybrid based on MoO3chains decorated with 2,2′-biimidazole ligands
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The discovery of selective heterogeneous catalytic systems for industrial oxidation processes remains a challenge. Molybdenum oxide-based polymeric hybrid materials have been shown to be oxidation catalysts under mild reaction conditions, although difficulties remain with catalyst recovery/reuse since most perform as homogeneous catalysts or possess low activity. The present study shows that the hybrid material [MoO3(2,2′-biimidazole)]·H2O (1) is a superior catalyst regarding these issues. The structure of1was confirmed (by single crystal and synchrotron X-ray powder diffraction) to comprise one-dimensional chains of corner-sharing {MoO4N2} octahedra. Strong MoO?H-N hydrogen bonds separate adjacent chains to afford parallel channels that are occupied by disordered water molecules. Hybrid1was additionally characterised by FT-IR spectroscopy,1H and13C MAS NMR, scanning electron microscopy and thermogravimetric analysis. The catalytic studies highlighted the versatility of1for oxidation reactions withtert-butylhydroperoxide as oxidant. By complementing with characterisation studies, it was verified that the reaction occurs in the heterogeneous phase, the catalyst has good stability and is recoverableviasimple procedures. The chemical reaction scope covered epoxidation and sulfoxidation, and the substrate scope included biomass-deriveddl-limonene and fatty acid methyl esters to give renewable bio-products, as well as thiophene and thioanisole substrates.
- Amarante, Tatiana R.,Neves, Patrícia,Almeida Paz, Filipe A.,Gomes, Ana C.,Pillinger, Martyn,Valente, Anabela A.,Gon?alves, Isabel S.
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p. 2214 - 2228
(2021/04/12)
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- Aldehyde-catalyzed epoxidation of unactivated alkenes with aqueous hydrogen peroxide
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The organocatalytic epoxidation of unactivated alkenes using aqueous hydrogen peroxide provides various indispensable products and intermediates in a sustainable manner. While formyl functionalities typically undergo irreversible oxidations when activating an oxidant, an atropisomeric two-axis aldehyde capable of catalytic turnover was identified for high-yielding epoxidations of cyclic and acyclic alkenes. The relative configuration of the stereogenic axes of the catalyst and the resulting proximity of the aldehyde and backbone residues resulted in high catalytic efficiencies. Mechanistic studies support a non-radical alkene oxidation by an aldehyde-derived dioxirane intermediate generated from hydrogen peroxide through the Payne and Criegee intermediates.
- Kokotos, Christoforos G.,Kokotou, Maroula G.,Lotter, Dominik,Sparr, Christof,Triandafillidi, Ierasia
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p. 10191 - 10196
(2021/08/12)
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- A silicododecamolybdate/pyridinium-tetrazole hybrid molecular salt as a catalyst for the epoxidation of bio-derived olefins
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The hybrid polyoxometalate (POM) salt (Hptz)4[SiMo12O40]?nH2O (1) (ptz = 5-(2-pyridyl)tetrazole) has been prepared, characterized by X-ray crystallography, and examined as a catalyst for the epoxidation of cis-cyclooctene (Cy) and bio-derived olefins, namely dl-limonene (Lim; a naturally occurring monoterpene found in the rinds of citrus fruits), methyl oleate and methyl linoleate (fatty acid methyl esters (FAMEs) obtained by transesterification of vegetable oils). The crystal structure of 1 consists of α-Keggin-type heteropolyanions, [SiMo12O40]4-, surrounded by space-filling and charge-balancing 2-(tetrazol-5-yl)pyridinium (Hptz+) cations, as well as by a large number of water molecules of crystallization (n = 9). The water molecules mediate an extensive three-dimensional (3D) hydrogen-bonding network involving the inorganic anions and organic cations. For the epoxidation of the model substrate Cy in a nonaqueous system (tert-butylhydroperoxide as oxidant), the catalytic performance of 1 (100% epoxide yield at 24 h, 70 °C) was superior to that of the tetrabutylammonium salt (Bu4N)4[SiMo12O40] (2) (63% epoxide yield at 24 h), illustrating the role of the counterion Hptz+ in enhancing catalytic activity. The hybrid salt 1 was effective for the epoxidation of Lim (69%/85% conversion at 6 h/24 h) and the FAMEs (87–88%/100% conversion at 6 h/24 h), leading to useful bio-based products (epoxides, diepoxides and diol products).
- Nunes, Martinique S.,Neves, Patrícia,Gomes, Ana C.,Cunha-Silva, Luís,Lopes, André D.,Valente, Anabela A.,Pillinger, Martyn,Gon?alves, Isabel S.
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- Sustainable catalytic epoxidation of biorenewable terpene feedstocks using H2O2as an oxidant in flow microreactors
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Solvent-free continuous flow epoxidation of the alkene bonds of a range of biorenewable terpene substrates have been carried out using a recyclable tungsten-based polyoxometalate phase transfer catalyst and aqueous H2O2 as a benign oxidant. These sustainable flow epoxidation reactions are carried out in commercial microreactors containing static mixing channels that enable common monoterpenes (e.g. untreated crude sulfate turpentine, limonene, etc.) to be safely epoxidized in short reaction times and in good yields. These flow procedures are applicable for the flow epoxidation of trisubstituted and disubstituted alkenes for the safe production of multigram quantities of a wide range of epoxides. This journal is
- Bull, Steven D.,Cunningham, William B.,Plucinski, Pawel,Tibbetts, Joshua D.,Vezzoli, Massimiliano
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supporting information
p. 5449 - 5455
(2021/08/16)
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- Modification of MnFe2O4 surface by Mo (VI) pyridylimine complex as an efficient nanocatalyst for (ep)oxidation of alkenes and sulfides
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In this current paper, we report a new type of heterogeneous molybdenum (+6) complex, prepared by covalent grafting of cis-dioxo?molybdenum (VI) pyridylimine complex on the surface of MnFe2O4 nanoparticles (NP) and characterized using various physicochemical techniques. The recyclable prepared nanocatalyst was tested for sulfoxidation of sulfides and epoxidation of alkenes under solvent-free condition. The catalyst exhibited high turnover frequency for the oxidization of cyclooctene and cyclohexene (10,850 h?1) and thioanisole and dimethyl sulfide (41,250 h?1). The synthesized catalyst was found highly efficient, retrievable and eco-friendly catalyst for the (ep)oxidation of alkenes and sulfides in excellent yields in a short time. Furthermore, the synthesized nanocatalyst can be reused for four runs without apparent loss of its catalytic activity in the oxidation reaction.
- Bouzari, Narges,Bezaatpour, Abolfazl,Babaei, Behnam,Amiri, Mandana,Boukherroub, Rabah,Szunerits, Sabine
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- Limonene dioxide as a building block for 100% bio-based thermosets
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This study valorises the benign epoxidation of (R)-(+)-limonene to generate novel bio-resourced limonene dioxide monomers. Without additional steps of separation or functionalization, the racemic limonene dioxide was cured with glutaric and dimethylglutaric anhydrides leading to thermosets with a high Tg (~98 °C) and good mechanical properties (σ = 27 MPa; ? = 3.5%; E = 1150 MPa; E′ = 1650 MPa, Shore D = 78). This journal is
- Mija, Alice,Louisy, Elodie,Lachegur, Sara,Khodyrieva, Veronika,Martinaux, Philippe,Olivero, Sandra,Michelet, Veronique
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supporting information
p. 9855 - 9859
(2021/12/24)
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- Homogeneous catalytic oxidation of alkenes employing mononuclear vanadium complex with hydrogen peroxide
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Abstract: Homogeneous liquid-phase oxidation of alkenes (allylbenzene, cis-cyclooctene, 4-chlorostyrene, styrene, 2-norbornene, 1-methyl cyclohexene, indene, lemonine, and 1-hexene) were catalyzed by using vanadium complex [VO(hyap)(acac)2] in existence of H2O2. The complex [VO(hyap)(acac)2] was formed as a crystal by the reaction of [VO(acac)2] and 2-hydroxyacetophenone (hyap) in the presence of methanol by refluxing the reaction mixture. Various analytical and spectroscopic techniques, namely FTIR, ESI–MS, UV–Vis, single-crystal XRD, and EPR, were used to analyze and optimize the structure of the complexes. Graphic abstract: [Figure not available: see fulltext.].
- Maurya, Abhishek
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p. 3261 - 3269
(2020/07/14)
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- Selective Formation of Epoxylimonene Catalyzed by Phosphonyl/Arsonyl Derivatives of Trivacant Polyoxotungstates at Low Temperature
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The catalytic performances of three organophosphonyl/arsonyl derivatives of POMs were evaluated for the epoxidation of limonene in acetonitrile, using aqueous H2O2 as the oxidant. All three W-based POMs catalysts operated without any additional transition-metal ions and displayed excellent conversion for limonene at temperatures varying from 4 to 50 °C. Furthermore, the use of B,α-[NaHAsW9O33{P(O)R}2]3– (R = tBu, -CH2CH2CO2H) complexes led to the complete conversion of limonene to epoxylimonene at 4 °C. The selectivity of the reaction was modulated by varying the reaction solvent, and it was found that allylic reactions were favored in ethanol. The effect of the catalyst protonation was also investigated by DFT calculations, highlighting the role of protons in the epoxidation process.
- Makrygenni, Ourania,Vanmairis, Louise,Taourit, Sabrina,Launay, Franck,Shum Cheong Sing, Alain,Proust, Anna,Gérard, Hélène,Villanneau, Richard
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p. 605 - 612
(2019/12/24)
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- Sustainable catalytic protocols for the solvent free epoxidation and: Anti -dihydroxylation of the alkene bonds of biorenewable terpene feedstocks using H2O2 as oxidant
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A tungsten-based polyoxometalate catalyst employing aqueous H2O2 as a benign oxidant has been used for the solvent free catalytic epoxidation of the trisubstituted alkene bonds of a wide range of biorenewable terpene substrates. This epoxidation protocol has been scaled up to produce limonene oxide, 3-carene oxide and α-pinene oxide on a multigram scale, with the catalyst being recycled three times to produce 3-carene oxide. Epoxidation of the less reactive disubstituted alkene bonds of terpene substrates could be achieved by carrying out catalytic epoxidation reactions at 50 °C. Methods have been developed that enable direct epoxidation of untreated crude sulfate turpentine to afford 3-carene oxide, α-pinene oxide and β-pinene oxide. Treatment of crude epoxide products (no work-up) with a heterogeneous acid catalyst (Amberlyst-15) results in clean epoxide hydrolysis to afford their corresponding terpene-anti-diols in good yields.
- Cunningham, William B.,Tibbetts, Joshua D.,Hutchby, Marc,Maltby, Katarzyna A.,Davidson, Matthew G.,Hintermair, Ulrich,Plucinski, Pawel,Bull, Steven D.
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supporting information
p. 513 - 524
(2020/02/13)
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- Synthesis of dipyroromethanes in water and investigation of electronic and steric effects in efficiency of olefin epoxidation by sodium periodate catalyzed by manganese tetraaryl and trans disubstituted porphyrin complexes
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Condensation of pyrrole with various aldehydes in the presence of BF3?etherate as an acid catalyst in water provides good yield of some dipyrromethanes. Prolongation of the reaction time with aldehydes substituted by electron-donating (mesityl) or electron-withdrawing (2,6-dichlorophenyl) groups on the ortho positions of the phenyl did not lead to decomposition or scrambling. Manganese trans disubstituted porphyrin complexes which derive from various dipyrromethanes and manganese tetraaryl porphyrin complexes including various substituents with different steric and electronic properties show good catalytic activity in epoxidation of alkenes by NaIO4 in the presence of imidazole (ImH). The study of steric and electronic effects of the catalysts on the epoxidation of olefins shows that Mn-porphyrin complexes with more bulky and electron-releasing groups on meso phenyls could increase the epoxidation yield of most alkenes.
- Bagherzadeh, Mojtaba,Jonaghani, Mohammad Adineh,Amini, Mojtaba,Mortazavi-Manesh, Anahita
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p. 671 - 678
(2019/04/26)
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- Safe, environment-friendly and controllable synthetic process of di-epoxide
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The invention relates to the field of synthesis of epoxide, and more specifically, relates to a safe, environment-friendly and controllable synthetic process of di-epoxide. The synthetic process of the di-epoxide at least comprises the following steps: mixing diolefin, carboxylic acids, basic salt and solvent, and cooling; dropwise adding a hydrogen peroxide solution for 1-12 h; standing for layering to obtain a lower layer organic phase-1, washing the organic phase-1 with a cleaning solution, and standing for layering to obtain a lower layer organic phase-2; purifying. The reaction system ofthe synthetic process is simple, environmentally friendly, safe and controllable, is low in production cost, and can meet the requirements of technical economy; the prepared di-epoxide is high in purity and yield and low in solvent content, chroma and halogen content, and is suitable for large-scale industrial production.
- -
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Paragraph 0169-0185
(2019/10/01)
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- High surface area, nanostructured boehmite and alumina catalysts: Synthesis and application in the sustainable epoxidation of alkenes
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We report a new, straightforward and inexpensive sol-gel route to prepare boehmite nanorods [γ-AlO(OH)-NR] with an average length of 23 nm ± 3 nm, an average diameter of 2 nm ± 0.3 nm and a high specific surface area of 448 m2/g, as evidenced by TEM and N2-physisorption, respectively. The boehmite was converted to γ-alumina with preserved nanorod morphology (γ-Al2O3-NR) and high surface area upon calcination either at 400 or 600 °C. These nanostructured materials are active and selective heterogeneous catalysts for the epoxidation of alkenes with the environmentally friendly H2O2. The best catalyst, γ-Al2O3-NR-400, showed to be versatile in the scope of alkenes that could be converted selectively to their epoxide and displayed enhanced reusability compared to previously reported alumina catalysts. Furthermore, the catalytic performance of the material was enhanced by optimising the reaction conditions such as the solvent and the type of hydrogen peroxide source. Under the optimised reaction conditions, the γ-Al2O3-NR-400 catalyst displayed 58% cyclooctene oxide yield after 4 h of reaction at 80 °C with full selectivity towards the epoxide product. The correlation between the catalytic activity of these materials and their physicochemical properties such as surface area, hydrophilicity and number and type of acid sites was critically discussed based on a detailed characterisation study.
- Lueangchaichaweng, Warunee,Singh, Bhawan,Mandelli, Dalmo,Carvalho, Wagner A.,Fiorilli, Sonia,Pescarmona, Paolo P.
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p. 180 - 187
(2019/01/04)
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- High-yield synthesis and catalytic response of chainlike hybrid materials of the [(MoO3): M(2,2′-bipyridine)n] family
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The one-dimensional organic-inorganic hybrid material [MoO3(2,2′-bipy)] (1) (2,2′-bipy = 2,2′-bipyridine) has been used as a starting material to prepare the bipy-deficient phases [Mo2O6(2,2′-bipy)] (2) and [Mo3O9(2,2′-bipy)2] (3) in excellent yields. The hybrid 2 was obtained by a solid-state thermal treatment of 1 (300 °C, 10 min) while 3 was obtained by a hydrothermal treatment of 1 (160 °C, 6 d). A study was performed to compare the catalytic properties of 1-3 in the epoxidation of cis-cyclooctene at 55 °C with tert-butylhydroperoxide (TBHP) or aqueous H2O2 as oxidant. In all cases Cy was converted to cyclooctene oxide (CyO) with 100% selectivity, and Cy conversions increased in the order 1 2O2 (cosolvent CH3CN). The catalytic reactions occurred in homogeneous phase with active species formed in situ from 1-3. All three hybrids react with aqueous H2O2 to give the catalytically active oxodiperoxo complex [MoO(O2)2(2,2′-bipy)]. The 2:1 hybrid 2 was further examined for the epoxidation of other cyclic and linear non-functionalised olefins with TBHP, namely cyclododecene, 1-octene and trans-2-octene, and the biomass-derived olefins dl-limonene, α-pinene and methyl oleate.
- Bruno, Sofia M.,Nogueira, Lucie S.,Gomes, Ana C.,Valente, Anabela A.,Gon?alves, Isabel S.,Pillinger, Martyn
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p. 16483 - 16492
(2018/10/24)
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- Preparation method of dipentene dioxide and application thereof
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The invention discloses a preparation method of dipentene dioxide and an application thereof. Raw materials used in the preparation method include limonene 10%-12%; toluene 40%-45%; acetic anhydride 18%-22%; sodium acetate 5%-8%; hydrogen peroxide solution 17%-20%. The sum of the mass of the above raw materials is 100%, and the percentage is the mass percentage. The dipentene dioxide prepared by the method has high yield, high selectivity and high purity, and is an excellent epoxy resin reactive diluent, almost has no effect on glass transition temperature of epoxy resin cure in the main epoxyresin curing process, and has high mechanical strength retention rate and good alkali resistance in the hot state.
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Paragraph 0031-0068
(2019/01/16)
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- Oxidation reactions catalysed by molybdenum(VI) complexes grafted on UiO-66 metal–organic framework as an elegant nanoreactor
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A heterogeneous catalyst was synthesized by immobilizing Mo(CO)3 in a UiO-66 metal–organic framework. The benzene ring of the organic linker in UiO-66 was modified via liquid-phase deposition of molybdenum hexacarbonyl, Mo(CO)6, as starting precursor to form the (arene)Mo(CO)3 species inside the framework. The structure of this catalyst was characterized using X-ray diffraction, and chemical integrity was confirmed using Fourier transform infrared and diffuse reflectance UV–visible spectroscopic methods. The metal content was analysed with inductively coupled plasma. Field emission scanning electron microscopy was used to measure particle size and N2 adsorption measurements to characterize the specific surface area. This catalytic system was efficiently applied for epoxidation of alkenes and oxidation of sulfides. The Mo-containing metal–organic framework was reused several times without any appreciable loss of its efficiency.
- Afzali, Niloufar,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mechler, Adam,Mohammadpoor-Baltork, Iraj,Kardanpour, Reihaneh,Zadehahmadi, Farnaz
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- New perspective to catalytic epoxidation of olefins by Keplerate containing Keggin polyoxometalates
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Different Keggin encapsulated in Keplerate polyoxometalates (Mo72Fe30, PMo12 ? Mo72Fe30, SiMo12 ? Mo72Fe30 and BW12 ? Mo72Fe30) have been synthesized and their catalytic efficiency in the epoxidation of olefins with hydrogen peroxide investigated. Results were confirmed that Keggin encapsulated in Keplerates could show higher catalytic activity than parent ones. These POM catalysts lead to heterogeneous epoxidation of alkenes by hydrogen peroxide with green features of convenient recovery, steady reuse, high conversion and selectivity, and simple preparation.
- Taghiyar, Hamid,Yadollahi, Bahram
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supporting information
p. 98 - 104
(2018/10/05)
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- Ionic ammonium and anilinium based polymolybdate hybrid catalysts for olefin epoxidation
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Ionic polymolybdate hybrids (IPH) are interesting catalysts for liquid phase olefin epoxidation with tert-butylhydroperoxide; (tbhp), e.g. conversion of terpenic and fatty acid methyl ester (FAME) components of biomass to useful bio-products. IPHs may be easily prepared, under clean, mild, aqueous phase conditions. The type of organic precursor and the synthesis conditions influence the structural features of the IPHs. In this work, IPH epoxidation catalysts possessing one- (1-D) or two-dimensional (2-D) structures were investigated, which included the new materials 1-D methylammonium ammonium trimolybdate [Mo3O10?CH3NH3·NH4] (1) and 2-D bis(2,5-dimethylanilinium) pentamolybdate [Mo5O16?2(NH3C6H3(CH3)2)] (4) with solved structures, and 1-D bis(3,5-dimethylanilinium) trimolybdate [Mo3O10·2(NH3C6H3(CH3)2)] (2), bis(4-methylanilinium) trimolybdate [Mo3O10·2(NH3C6H4CH3)] (3), 2-D bis(anilinium) pentamolybdate [Mo5O16?2(NH3C6H5)] (5), bis(4-methylanilinium) pentamolybdate [Mo5O16?2(NH3C6H4CH3)] (6) and bis(4-ethylanilinium) pentamolybdate [Mo5O16?2(NH3C6H4C2H5)] (7). Systematic characterisation and catalytic studies helped gain insights into structure-activity relationships. The best-performing catalyst (2) was effective for the epoxidation of the FAMEs such as, methyl oleate which gave 92% methyl 9,10-epoxyoctadecanoate yield, at 99% conversion, at 70 °C. The reaction conditions (temperature, type of cosolvent and oxidant) influenced the catalytic reaction. Catalytic performance in consecutive batch runs was steady, and the structural features were essentially preserved.
- Bo?ek, Barbara,Neves, Patrícia,?asocha, Wies?aw,Valente, Anabela A.
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- Performance of chiral tetracarbonylmolybdenum pyrindanyl amine complexes in catalytic olefin epoxidation
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Tetracarbonylmolybdenum(0) complexes of the type cis-[Mo(CO)4(L)] containing chiral 7-(1-pyrindanyl) amine ligands were prepared and found to be effective precatalysts for the epoxidation of achiral (cis-cyclooctene) and prochiral (DL-limonene and trans-β-methylstyrene) olefins at 55 °C. Epoxides were the only products formed from cis-cyclooctene (100% yield) and trans-β-methylstyrene (100% selectivity at 82–85% conversion), and the main products formed from DL-limonene (80–82% 1,2-epoxide selectivity at 85% conversion). Characterization of recovered catalysts revealed that the precatalysts were transformed in situ to stable polyoxomolybdate salts containing the β-octamolybdate anion [β-Mo8O26]4?, which was responsible for the catalytic reaction.
- Neves, Patrícia,Nogueira, Lucie S.,Valente, Anabela A.,Pillinger, Martyn,Gon?alves, Isabel S.,Sampaio-Dias, Ivo E.,Sousa, Carlos A.D.,Rizzo-Aguiar, Fabio,Rodríguez-Borges, José E.
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- Epoxidation of limonene over low coordination Ti in Ti- SBA-16
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Epoxidation of limonene was studied over Ti-SBA-16 catalysts prepared using two different post grafting techniques. The first one consisted of an in-situ synthesis of a titanium acetylacetone (ACAC) precursor and the other one used directly TiO(ACAC)2. Reaction conditions such as temperature, concentration of TBHP and solvent polarity were examined. The reaction should be carried out at 75?°C in acetonitrile using a TBHP/limonene molar ratio of 11/6. The conversion of limonene reached 80% with a 1,2-limonene oxide selectivity of 79% for both impregnation methods using Ti-SBA-16 with a Ti/Si atomic ratio of 7.3%. Under the same conditions the 3D pore structure of SBA-16 support favors reactants and products mass transfer compared to the 2D pore structure of SBA-15. No differences in catalytic activity were observed as atomic ratio Ti/Si was varied from 5 to 13.4% in Ti-SBA-16. Repeated catalytic tests showed no change in activity over three process cycles.
- Charbonneau, Luc,Kaliaguine, Serge
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- Chemistry and Catalytic Performance of Pyridyl-Benzimidazole Oxidomolybdenum(VI) Compounds in (Bio)Olefin Epoxidation
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The chemistry and catalytic performance of the dichlorido complex [MoO2Cl2(pbim)] (1) [pbim = 2-(2-pyridyl)-benzimidazole] in the epoxidation of olefins is reported. Complex 1 acts as a precatalyst and is more effective with tert-butylhydroperoxide (TBHP) as the oxidant than with aq. hydrogen peroxide: the cis-cyclooctene (Cy) reaction with TBHP gave 98 % epoxide yield at 70 °C/24 h. Catalyst characterization showed that 1 is transformed in situ to the oxidodiperoxido complex [MoO(O2)2(pbim)] (2), with H2O2 and a hybrid molybdenum(VI) oxide solid formulated as [MoO3(pbim)] (3) with TBHP. The hybrid material 3 was prepared on a larger scale and explored for the epoxidation of the biorenewable olefins methyl oleate, methyl linoleate, and (R)-(+)-limonene. With TBHP as the oxidant, 3 acts as a source of soluble active species of the type 2. A practical method for recycling oxidodiperoxidomolybdenum(VI) catalysts for the Cy/TBHP reaction is demonstrated by using an ionic liquid as the solvent for the molecular catalyst 2.
- Neves, Patrícia,Nogueira, Lucie S.,Gomes, Ana C.,Oliveira, Tania S. M.,Lopes, André D.,Valente, Anabela A.,Gon?alves, Isabel S.,Pillinger, Martyn
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p. 2617 - 2627
(2017/05/29)
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- Development of a lipase-mediated epoxidation process for monoterpenes in choline chloride-based deep eutectic solvents
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Chemical syntheses in contemporary process industries today are predominantly conducted using organic solvents, which are potentially hazardous to humans and the environment alike. Green chemistry was developed as a means to overcome this hazard and it also holds enormous potential for designing clean, safe and sustainable processes. The present work incorporates the concepts of green chemistry in its design of a lipase-mediated epoxidation process for monoterpenes; the process uses alternative reaction media, namely deep eutectic solvents (DESs), which have not been reported for such an application before. Choline chloride (ChCl), in combination with a variety of hydrogen bond donors (HBD) at certain molar ratios, was screened and tested for this purpose. The process was optimized through the design of experiments (DoE) using the Taguchi method for four controllable parameters (temperature, enzyme amount, peroxide amount and type of substrate) and one uncontrollable parameter (DES reaction media) in a crossed-array design. Two distinct DESs, namely glycerol:choline chloride (GlCh) and sorbitol:choline chloride (SoCh), were found to be the best systems and they resulted in a complete conversion of the substrates within 8 h. Impurities (esters) were found to form in both the DESs, which was a concern; as such, we developed a novel minimal DES system that incorporated a co-substrate into the DES so that this issue could be overcome. The minimal DES consisted of urea·H2O2 (U·H2O2) and ChCl and exhibited better results than both the GlCh and SoCh systems; complete conversions were achieved within 2 h for 3-carene and within 3 h for both limonene and α-pinene. Product isolation with a simple water/ethyl acetate based procedure gave isolated yields of 87.2 ± 2.4%, 77.0 ± 5.0% and 84.6 ± 3.7% for 3-carene, limonene and α-pinene respectively.
- Ranganathan, Sumanth,Zeitlhofer, Sandra,Sieber, Volker
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p. 2576 - 2586
(2017/07/24)
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- Synthesis, characterization and catalytic application of a new organometallic oligomer based on polyhedral oligomeric silsesquioxane
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Although homogeneous catalysts provide high performance and selectivity, the difficulty of separation and recycling of these catalysts has bothered the scientific community worldwide. Therefore, the demand for heterogeneous catalysts that possess the advantages of homogeneous ones, with ease of separation and recyclability remains a topic of major impact. The oligomeric catalyst synthesized in this work was characterized using elemental analysis, Fourier transform infrared, 13C NMR, 29Si NMR and energy-dispersive X-ray spectroscopies, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and Brunauer–Emmett–Teller analysis and compared to its homogeneous counterpart [W(CO)3Br2(ATC)] in the epoxidation of 1-octene, cyclooctene, (S)-limonene, cis-3-hexen-1-ol, trans-3-hexen-1-ol and styrene. The results showed that the percentage conversion for the homogeneous species [W(CO)3Br2(ATC)] was slightly higher than for the oligomeric catalyst (POSS-ATC-[W(CO)3Br2]). Furthermore, the selectivity for epoxide of the oligomeric catalyst was greater than that of the homogeneous catalyst by about 25% when (S)-limonene was used. Great conversions (yields) of products were obtained with a wide range of substrates and the catalyst was recycled many times without any substantial loss of its catalytic activity.
- Vieira, Eduardo Guimar?es,Silva, Rafael Oliveira,Junior, Enes Furlani,Dias Filho, Newton Luiz
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- Catalytic homogeneous oxidation of monoterpenes and cyclooctene with hydrogen peroxide in the presence of sandwich-type tungstophosphates [M4(H2O)2(PW9O34)2]n?, M = CoII, MnII and FeIII
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Catalytic efficiency of tetrabutylammonium salts of sandwich tungstophosphates B‐α‐[M4(H2O)2(PW9O34)2]n?, M = CoII, MnII, FeIII, was studied in the oxidation of (R)-(+)-limonene, geraniol, linalool, linalyl acetate, carveol, and cis-cyclooctene with hydrogen peroxide, in acetonitrile. Oxidation of (R)-(+)-limonene gave limonene-1,2-diol as main product. Epoxidation of linalool takes place preferentially at the more substituted 6,7-double bond, the corresponding 6,7-epoxide reacting further, yielding furano- and pyrano-oxides, via intramolecular cyclization. Oxidation of linalyl acetate occurred preferentially at the more substituted 6,7-double bond for Mn4(PW9)2, affording 6,7-epoxide at 82% selectivity. Linalyl acetate 1,2-epoxide was the major product with 51% and 77% selectivity for Co4(PW9)2 and Fe4(PW9)2, respectively. Oxidation of carveol occurred with very good conversions in the presence of Mn4(PW9)2, Co4(PW9)2 and Fe4(PW9)2, yielding carvone and carveol 1,2-epoxide in similar amounts. Oxidation of cis-cyclooctene gave only the epoxide, while oxidation of geraniol at room temperature afforded 2,3-epoxygeraniol as the major product.
- Santos, Isabel C.M.S.,Gamelas, José A.F.,Duarte, Tiago A.G.,Sim?es, Mário M.Q.,Neves, M. Gra?a P.M.S.,Cavaleiro, José A.S.,Cavaleiro, Ana M.V.
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p. 593 - 599
(2016/12/16)
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- Oxidation of olefins with H2O2 catalyzed by gallium(III) nitrate and aluminum(III) nitrate in solution
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Soluble gallium and aluminum nitrates (simple salts of non-transition metals) are good catalysts for the epoxidation of olefins (cyclooctene, dec-1-ene) including terpenes (carvone, limonene) with hydrogen peroxide in ethyl acetate or tetrahydrofurane (THF). Typically, the gallium salt is more efficient in comparison with the aluminum derivative. Products are formed in yields up to 93%, turnover numbers (TONs) attained 40. Addition of trifluoroacetic acid or pyrazine-2-carboxylic acid (PCA) accelerates the reaction and improves the yield. In striking contrast, added 2,2′-bipyridine or phenanthroline dramatically inhibit the oxidation.
- Mandelli, Dalmo,Kozlov, Yuriy N.,da Silva, Cezar A.R.,Carvalho, Wagner A.,Pescarmona, Paolo P.,Cella, Daniele de A.,de Paiva, Polyana T.,Shul'pin, Georgiy B.
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p. 216 - 220
(2016/09/19)
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- Immobilizing of oxo-molybdenum complex on cross-linked copolymer and its catalytic activity for epoxidation reactions
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This work describes the immobilization of molybdenum acetylacetonate oxygen (MoO2(acac)2) on cross-linked porous copolymer support via covalent attachment under mild conditions. The obtained solid product DVB-AA-Mo was fully characterized by FT-IR, TG, CHN elemental analysis, nitrogen adsorption/desorption, and SEM, and was tested for the epoxidation of various alkenes with tert-butyl hydroperoxide (TBHP) as the oxidant. DVB-AA-Mo was proved to be a highly efficient catalyst for epoxidation reactions, it could easily be recovered by filtration and reused for five runs without significant loss in activity.
- Fan, Weizheng,Shi, Dongyang,Feng, Bainian
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- Regioselective Organocatalytic Formation of Carbamates from Substituted Cyclic Carbonates
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A highly regioselective catalytic approach has been developed towards carbamates derived from cyclic organic carbonates by reaction of the latter with amine reagents under organocatalytic control. For various combinations of carbonate and amine substrates, an organocatalyst (TBD: 1,5,7-triazabicyclo[4.4.0]dec-5-ene) was used to increase the reaction kinetics while exerting excellent regioselective control. The current method is the first general approach towards the control over the regioselectivity of this reaction using a wide variety of easily accessed substituted organic carbonates. (Figure presented.) .
- Sope?a, Sergio,Laserna, Victor,Guo, Wusheng,Martin, Eddy,Escudero-Adán, Eduardo C.,Kleij, Arjan W.
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supporting information
p. 2172 - 2178
(2016/07/16)
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- Optimization of the lipase mediated epoxidation of monoterpenes using the design of experiments—Taguchi method
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This work deals with the optimization of the Candida antartica lipase B (CALB) mediated epoxidation of monoterpenes by using the design of experiments (DoE) working with the Taguchi Method. Epoxides are essential organic intermediates that find various industrial applications making the epoxidation one of the most investigated processes in chemical industry. As many as 8 parameters such as the reaction medium, carboxylic acid type, carboxylic acid concentration, temperature, monoterpene type, monoterpene concentration, hydrogen peroxide concentration and amount of lipase were optimized using as less as 18 runs in triplicates (54 runs). As a result, the hydrogen peroxide concentration used was found to be the most influential parameter of this process while the type of monoterpene was least influential. Scaling up of the reaction conditions according to the findings of the optimization achieved full conversion in less than 6?h. In addition, a purification process for the epoxides was developed leading to an isolated yield of ca. 72.3%, 88.8% and 62.5% for α-pinene, 3-carene and limonene, respectively.
- Ranganathan, Sumanth,Tebbe, Johannes,Wiemann, Lars O.,Sieber, Volker
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p. 1479 - 1485
(2016/10/03)
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- Syntheses and catalytic activities of new metallodendritic catalysts
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This investigation presents the syntheses of new metallodendritic catalysts from a silsesquioxane core (Silsesq-PrNH3+Cl-) via a new route. For optimization of the syntheses of the catalysts, reaction times, thermodynamic effects, and the amounts of [Mo(η3-C3H5)Br(CO)2(NCCH3)2] (1) and [Mo(CO)3Br2(NCCH3)2] (2) complexes fixed on the second-generation dendrimer (PDG2.0) were studied. After the optimization studies and with the objective of application in catalysis, the catalysts were prepared by reaction of PDG2.0 with the organometallic complexes and characterized by elemental analysis (CNH), FTIR, 13C and 29Si NMR, XRD, TGA, SEM, EDS and BET. The metallodendritic catalysts were tested in the epoxidation of olefins and shown to be a vigorous catalyst with conversion rates between 76 and 97% for PDG2.0-[(Mo(η3-C3H5)(CO)2Br)8] and 30-80% for PDG2.0-[(Mo(CO)3Br2)5], and a high selectivity in the formation of epoxides using tertbutyl hydroperoxide (TBHP) as an oxidant. The catalysts remain highly active after being used for at least 5 cycles. To the best of our knowledge, this study is the first to have reported the preparation of these new dendritic catalysts, as well as the catalytic comparison with their previous generations in the epoxidation of 1-octene, cyclooctene, (S)-limonene, cis-3-hexen-1-ol, trans-3-hexen-1-ol and styrene.
- Vieira, Eduardo Guimar?es,Silva, Rafael Oliveira,Dal-Bó, Alexandre Gon?alves,Frizon, Tiago Elias Allievi,Filho, Newton Luiz Dias
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p. 9403 - 9414
(2016/11/09)
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- Cis-Dioxomolybdenum(VI) complexes with unsymmetric linear tetradentate ligands: Syntheses, structures and bromoperoxidase activities
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Reactions of [MoO2(acetylacetonate)2], 2-((2-(2-hydroxyethylamino)ethylamino)methyl)-4-R-phenols (H2Ln, n = 1-5 for R = H, Me, OMe, Cl and Br, respectively) and KOH in 1:1:2 mole ratio in methanol afford a series of complexes having the general formula cis-[MoO2(Ln)] (1, 2, 3, 4, 5) in 81-86% yields. The complexes have been characterized using elemental analysis, spectroscopy (infrared, UV-visible, and 1H NMR, 13C NMR and 13C-DEPT NMR) and electrochemical measurements. The molecular structures of 1, 2, 3, 4 have been determined using single-crystal X-ray crystallography. In each of 1, 2, 3, 4, the ONNO-donor 6,5,5-membered fused chelate rings forming (Ln)2- and the two mutually cis oxo groups assemble a distorted octahedral N2O4 coordination sphere around the metal centre. In the crystal lattice, each of 1, 2, 3, 4 forms a one-dimensional infinite chain structure via intermolecular N-H...O hydrogen bonding interactions. In cyclic voltammograms, the diamagnetic complexes display an irreversible metal-centred reduction in the potential range -0.73 to -0.88 V (vs Ag/AgCl). The physicochemical data are consistent with a very similar gross molecular structure for all of 1, 2, 3, 4, 5. All the complexes exhibit decent bromoperoxidase activities and are also able to effectively catalyse benzoin and methyl(phenyl)sulfide oxidation reactions.
- Kurapati, Sathish Kumar,Pal, Samudranil
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p. 116 - 124
(2016/02/18)
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- Catalytic activity of molybdenum(II) complexes in homogeneous and heterogeneous conditions
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The new complexes [MoBr(η3-C3H5)(CO)2(L)2] (C1) and [MX2(CO)3(L)2] (M = Mo(II), X = I (C2); M = Mo(II), X = Br (C3); M = W(II), X = I (C4); M = W(II), X = Br (C5)) were synthesized by reaction of 2-amino-1,3,4-thiadiazole (L) with [MoBr(η3-C3H5)(CO)2(NCCH3)2] (1), [MoI2(CO)3(CH3CN)2](M = Mo (2); M = W (4)), or [MoBr2(CO)3(CH3CN)2](M = Mo (3); M = W (5)) in 2:1 ratio. The five complexes were immobilized in MCM-41, yielding the materials MCM-Cn (n = 1-5), and C1 was also immobilized in silica gel (Silica-C1) and in a polyhedral oligomeric silsesquioxane (Cube-C1). Complexes and materials were fully characterized by spectroscopic techniques and elemental analysis. DFT calculations showed that several C1 isomers should coexist. The as synthesized and supported complexes were tested as catalysts on the oxidation of geraniol, cis-hex-3-en-1-ol, trans-hex-3-en-1-ol, (S)-limonene, and 1-octene. The conversions and TOF significantly depend on the complex and the nature of the substrate. The general conclusions are (i) complex C1 has the highest activity; (ii) tungsten complexes C4 and C5 are more active than the molybdenum analogues; (iii) the immobilization of the catalysts improves the performance; and (iv) silica gel and the polyhedral oligomeric silsesquioxane supports modify the selectivity, leading to products different from the one obtained with MCM for specific substrates.
- Vasconcellos Dias, Maria,Saraiva, Marta S.,Ferreira, Paula,Calhorda, Maria José
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p. 1465 - 1478
(2015/05/13)
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- An ionic liquid immobilized copper complex for catalytic epoxidation
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This article brings into focus an in situ strategy of immobilization of a copper complex onto an ionic liquid support. A practical method of olefin and terpene epoxidation by immobilizing a copper complex and 1-ethyl-3-methylimidazolium hexafluorophosphate and using H2O2 as the terminal oxidant is developed. The advantageous properties of this catalytic system redefine an exceptionally clean environment for catalytic epoxidations.
- Dileep,Rudresha
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p. 65870 - 65873
(2015/08/18)
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- A versatile method of epoxide formation with the support of peroxy ionic liquids
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The application of the peroxy ionic liquid, 1-butyl-3-methylimidazolium peroxymonosulphate, as an oxidation agent and a solvent for the synthesis of epoxides was described. The 2.5-molar excess of the peroxy ionic liquid to olefin was applied. The reaction system consisted of 1,1,1-trifluoroacetone as an oxirane precursor, which was used with the molar ratio of 1:3 relative to olefin and water solution of NaHCO3. Under these conditions the epoxidation of 4-bromocinnamic acid led to the epoxide formation at the ambient temperature in 30 minutes. Dioxiranes, generated from the peroxy ionic liquid and 1,1,1-trifluoroacetone, demonstrated encouraging potential for the epoxidation of a variety of other olefins: styrene, limonene, stilbene, linalyl acetate and a complex steroid molecule with high yields of final epoxides from 65-98%.
- Zawadzki, Przemys?aw,Matuszek, Karolina,Czardybon, Wojciech,Chrobok, Anna
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p. 5282 - 5286
(2015/07/07)
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- Pore size matters! Helical heterogeneous catalysts in olefin oxidation
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Helical mesoporous materials of the MCM-41 type with different pore sizes were prepared, choosing as templates myristyl (C14) or cetyl (C16) trimethyl ammonium salts, and functionalized with Mo(II) active sites based on MoI2(CO)3 (1) and MoBr(η3-C3H5)(CO)2 (2) fragments, respectively, using a pyridine-2-carbaldehyde ligand as anchor. The new materials were tested as the catalytic precursors in the epoxidation of cis-cyclooctene, styrene, R-(+)-limonene, trans-hex-2-en-1-ol, cis-3-hex-1-ol, and geraniol using tert-butylhydroperoxide (tbhp) as oxidant. All catalysts were moderately to highly selective toward the epoxide products. The materials with larger pores (C16 template) displayed a better catalytic activity, leading in general to higher conversions and selectivities, as well as faster kinetics. For instance, geraniol is epoxidized (more than 90%) with conversions above 90%. The major achievement of these catalysts, however, is the excellent product selectivity control, which is boosted when the allyl complex 1 is used, reaching 100% of the 2S, 3R species in the epoxidation of trans-hex-2-en-1-ol. The catalysts were also found to be stable through recycling experiments and truly heterogeneous with little or no leaching.
- Saraiva, Marta S.,Fernandes, Cristina I.,Nunes, Teresa G.,Calhorda, Maria José,Nunes, Carla D.
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p. 328 - 337
(2015/10/05)
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- Crystal Structure and Catalytic Behavior in Olefin Epoxidation of a One-Dimensional Tungsten Oxide/Bipyridine Hybrid
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The tungsten oxide/2,2′-bipyridine hybrid material [WO3(2,2′-bpy)]·nH2O (n = 1-2) (1) has been prepared in near quantitative yield by the reaction of H2WO4, 2,2′-bpy, and H2O in the mole ratio of ca. 1:2:700 at 160°C for 98 h in a rotating Teflon-lined digestion bomb. The solid-state structure of 1 was solved and refined through Rietveld analysis of high-resolution synchrotron X-ray diffraction data collected for the microcrystalline powder. The material, crystallizing in the orthorhombic space group Iba2, is composed of a one-dimensional organic-inorganic hybrid polymer, ∞1[WO3(2,2′-bpy)], topologically identical to that found in the previously reported anhydrous phases [MO3(2,2′-bpy)] (M = Mo, W). While in the latter the N,N′-chelated 2,2′-bpy ligands of adjacent corner-shared {MO4N2} octahedra are positioned on the same side of the 1D chain, in 1 the 2,2′-bpy ligands alternate above and below the chain. The catalytic behavior of compound 1 for the epoxidation of cis-cyclooctene was compared with that for several other tungsten- or molybdenum-based (pre)catalysts, including the hybrid polymer [MoO3(2,2′-bpy)]. While the latter exhibits superior performance when tert-butyl hydroperoxide (TBHP) is used as the oxidant, compound 1 is superior when aqueous hydrogen peroxide is used, allowing near-quantitative conversion of the olefin to the epoxide. With H2O2, compounds 1 and [MoO3(2,2′-bpy)] act as sources of soluble active species, namely, the oxodiperoxo complex [MO(O2)2(2,2′-bpy)], which is formed in situ. Compounds 1 and [WO(O2)2(2,2′-bpy)] (2) were further tested in the epoxidation of cyclododecene, trans-2-octene, 1-octene, (R)-limonene, and styrene. The structure of 2 was determined by single-crystal X-ray diffraction and found to be isotypical with the molybdenum analogue.
- Amarante, Tatiana R.,Antunes, Margarida M.,Valente, Anabela A.,Paz, Filipe A. Almeida,Pillinger, Martyn,Gon?alves, Isabel S.
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p. 9690 - 9703
(2015/11/03)
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- Regioselective Cleavage of Electron-Rich Double Bonds in Dienes to Carbonyl Compounds with [Fe(OTf)2(mix-BPBP)] and a Combination of H2O2 and NaIO4
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A method for the regioselective transformation of dienes to carbonyl compounds has been developed. Electron-rich olefins react selectively to yield valuable aldehydes and ketones. The method is based on the catalyst [Fe(OTf)2(mix-BPBP)] with an oxidant combination of H2O2 (1.0 equiv.) and NaIO4 (1.5 equiv.); it uses mild conditions and short reaction times, and it outperforms other olefin cleavage methodologies. The combination of an Fe-based catalyst, [Fe(OTf)2(mix-BPBP)], and the oxidants H2O2 and NaIO4 can discriminate between electronically different double bonds and oxidatively cleave the electron-rich bond in dienes to yield aldehydes and ketones in a regioselective manner. The reaction requires mild conditions (0-50 C) and short reaction times (70 min).
- Spannring, Peter,Yazerski, Vital A.,Chen, Jianming,Otte, Matthias,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.,Klein Gebbink, Robertus J. M.
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p. 3462 - 3466
(2015/08/06)
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- Investigation of a dichlorodioxomolybdenum(vi)-pyrazolylpyridine complex and a hybrid derivative as catalysts in olefin epoxidation
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Treatment of the solvent adduct [MoO2Cl2(THF) 2] with the ligand 2-(1-pentyl-3-pyrazolyl)pyridine (1, abbreviated as pent-pp) gave the dioxomolybdenum(vi) complex [MoO2Cl 2(pent-pp)] (2), which was characterised by elemental analysis, 1H NMR, FT-IR spectroscopy and single crystal X-ray diffraction (XRD). Reaction of 2 with water in a Teflon-lined stainless steel autoclave at 100 °C led to the isolation of a molybdenum oxide/pyrazolylpyridine hybrid material with the composition [Mo2O6(pent-pp)] (3), which was characterised by variable temperature powder XRD, scanning electron microscopy, thermogravimetric analysis, FT-IR and 13C{1H} CP MAS NMR spectroscopies. Compounds 2 and 3 display high activity and selectivity when used as (pre)catalysts for the epoxidation of cis-cyclooctene at 55 °C with tert-butylhydroperoxide as an oxidant. Further catalytic experiments with 3 as a (pre)catalyst were performed using the bio-derived olefins dl-limonene (Lim) and methyl oleate (Ole). The reaction of Lim gave mainly 1,2-epoxy-p-menth-8-ene and 1,2;8,9-diepoxy-p-menthane in a combined yield of 93% at 97% conversion (6 h), while the reaction of Ole led to 9,10-epoxystearate as the main product in 78% yield at 82% conversion (6 h). The catalytic reactions are homogeneous in nature. Starting with material 3, the oxodiperoxo complex [MoO(O2)2(pent-pp)] (4) was isolated from solution after a catalytic run, suggesting that it is formed from 3 and plays a catalytic role. This journal is the Partner Organisations 2014.
- Amarante, Tatiana R.,Neves, Patricia,Paz, Filipe A. Almeida,Valente, Anabela A.,Pillinger, Martyn,Goncalves, Isabel S.
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p. 6059 - 6069
(2014/04/17)
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- Limonene epoxidation with H2O2 promoted by Al2O3: Kinetic study, experimental design
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A highly efficient oxidation of limonene with hydrogen peroxide promoted by cheap aluminum oxide has been studied. The reaction is a rare example of the epoxidation promoted by a derivative of non-transition metal having a single stable non-zero oxidation state (SSOS metal), and it affords epoxides which are highly valuable products (fragrances, food additives and monomers). Typically, ethyl acetate at 80 °C was used as a solvent. The experimental data have been described by the proposed kinetic scheme. The optimization of the limonene epoxidation using a 23 experimental design has been carried out.
- Bonon, Anderson J.,Kozlov, Yuriy N.,Bahú, Juliana O.,Filho, Rubens Maciel,Mandelli, Dalmo,Shul'pin, Georgiy B.
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- New Mo(II) complexes in MCM-41 and silica: Synthesis and catalysis
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The new complexes [MoI2(CO)3(L1)] (1) and [MoI2(CO)3(L2)] (2) were prepared from reaction of [MoI2(CO)3(NCMe)2] with the ligands 2-(2′-hydroxyphenyl)imidazoline (L1), and 2-(2′- hydroxyphenyl) benzimidazole (L2). These complexes were immobilized in MCM-41 and in silica gel, by grafting (3- chloropropyl)trimethylsilane on the surface of the materials and allowing it to react with [MoI2(-CO) 3(L1)] (1) or [MoI2(CO)3(L 2)] (2). All the molybdenum derivatives were characterized by NMR and FTIR spectroscopies, which showed coordination of L1 and L 2 in neutral form. The structure of the MCM materials was analyzed by powder X-ray diffraction and nitrogen adsorption isotherms. The catalytic activity of the complexes and materials was tested in several substrates (cis-cyclooctene, styrene, 1- octene, R-(+)limonene, geraniol, cis-hex-3-en-1-ol and trans-hex-2-en-1-ol), using tert-butylhydroperoxide (TBHP) as oxidant. Complexes 1 and 2 were in general the more active catalysts and 100% selective towards the epoxide of cis-cyclooctene. Complex 1 immobilized in silica (Si-Pr-1) was the best material, showing higher conversion than 1 in the oxidation of R-(+)limonene, with comparable selectivity towards the ring epoxide.
- Saraiva, Marta S.,Fernandes, Cristina I.,Nunes, Teresa G.,Nunes, Carla D.,Calhorda, Maria José
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p. 443 - 452
(2014/03/21)
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- Oxidative catalytic versatility of a trivacant polyoxotungstate incorporated into MIL-101(Cr)
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The first immobilization of the trivacant Keggin-type polyoxometalate ([A-PW9O34]9-, PW9) to prepare a novel heterogeneous oxidative catalyst is here reported. PW9 was incorporated into the cavities of the chromium terephthalate metal-organic framework MIL-101(Cr). Characterization of the composite PW9@MIL-101 by powder X-ray diffraction, SEM-EDX, FT-IR, FT-Raman spectroscopy, N 2 adsorption-desorption isotherms and 31P solid-state NMR confirmed that the structures of MIL-101 and the polyoxometalate anion were retained after immobilization. The composite PW9@MIL-101 revealed versatility as a heterogeneous catalyst to oxidize efficiently monoterpenes as well as to reach a complete desulfurization of a model oil containing the most refractory sulfur compounds in fuel, using in both systems acetonitrile as the solvent and H2O2 as the oxidant. Complete conversion of geraniol to 2,3-epoxygeraniol was achieved after the first 30 min at room temperature, while the total desulfurization of the model oil containing 1707 ppm of sulfur was attained after 2 h. In both systems the catalyst was recyclable for various cycles without a significant loss of activity. The stability and heterogeneity of the catalyst were confirmed by several techniques and by leaching tests. the Partner Organisations 2014.
- Granadeiro, Carlos M.,Barbosa, Andre D. S.,Ribeiro, Susana,Santos, Isabel C. M. S.,De Castro, Baltazar,Cunha-Silva, Luis,Balula, Salete S.
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p. 1416 - 1425
(2014/05/06)
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- 2,2,2-Trifluoroacetophenone: An organocatalyst for an environmentally friendly epoxidation of alkenes
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A cheap, mild, fast, and environmentally friendly oxidation of olefins to the corresponding epoxides is reported using polyfluoroalkyl ketones as efficient organocatalysts. Namely, 2,2,2-trifluoroacetophenone was identified as an improved organocatalyst for the epoxidation of alkenes. Various olefins, mono-, di-, and trisubstituted, are epoxidized chemoselectively in high to quantitative yields utilizing 2-5 mol % catalyst loading and H2O 2 as the green oxidant.
- Limnios, Dimitris,Kokotos, Christoforos G.
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p. 4270 - 4276
(2014/06/09)
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- Efficient epoxidation of olefins by H2O2 catalyzed by iron "helmet" phthalocyanines
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High yields of epoxides were obtained in the oxidation of a large range of olefins using 1.2-2 equiv. of H2O2 in the presence of iron helmet phthalocyanines. The involvement of high-valent iron oxo species was evidenced using cryospray mass spectrometry.
- Skobelev, Igor Y.,Kudrik, Evgeny V.,Zalomaeva, Olga V.,Albrieux, Florian,Afanasiev, Pavel,Kholdeeva, Oxana A.,Sorokin, Alexander B.
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p. 5577 - 5579
(2013/07/25)
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- Hydrothermal synthesis, crystal structure, and catalytic potential of a one-dimensional molybdenum oxide/bipyridinedicarboxylate hybrid
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The reaction of MoO3, 2,2′-bipyridine-5,5-dicarboxylic acid (H2bpdc), water, and dimethylformamide in the mole ratio 1:1:1730:130 at 150 C for 3 days in a rotating Teflon-lined digestion bomb leads to the isolation of the molybdenum oxide/bipyridinedicarboxylate hybrid material (DMA)[MoO3(Hbpdc)]·nH2O (1) (DMA = dimethylammonium). Compound 1 was characterized by scanning electron microscopy, FT-IR and 13C{1H} CP MAS NMR spectroscopies, and elemental and thermogravimetric analyses. The solid state structure of 1 was solved and refined through Rietveld analysis of high resolution synchrotron X-ray powder diffraction data in conjunction with information derived from the above techniques. The material, crystallizing in the noncentrosymmetric monoclinic space group Pc, is composed of an anionic one-dimensional organic-inorganic hybrid polymer, ∞1[MoO 3(Hbpdc)]-, formed by corner-sharing distorted {MoO 4N2} octahedra, which cocrystallizes with charge-balancing DMA+ cations and one water molecule per metal center. In the crystal structure of 1, the close packing of individual anionic polymers, DMA + cations, and water molecules is mediated by a series of supramolecular contacts, namely strong (O-H···O, N +-H···O-) and weak (C-H···O) hydrogen bonding interactions, and π-π contacts involving adjacent coordinated Hbpdc- ligands. The catalytic potential of 1 was investigated in the epoxidation reactions of the bioderived olefins methyl oleate (Ole) and dl-limonene (Lim) using tert-butylhydroperoxide (TBHP) as the oxygen donor and 1,2-dichloroethane (DCE) or (trifluoromethyl) benzene (BTF) as cosolvent, at 55 or 75 C. Under these conditions, 1 acts as a source of active soluble species, leading to epoxide yields of up to 98% for methyl 9,10-epoxystearate (BTF, 75 C, 100% conversion of Ole) and 89% for 1,2-epoxy-p-menth-8-ene (DCE, 55 C, 95% conversion of Lim). Catalytic systems employing the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide as solvent could be effectively recycled.
- Amarante, Tatiana R.,Neves, Patricia,Valente, Anabela A.,Almeida Paz, Filipe A.,Fitch, Andrew N.,Pillinger, Martyn,Goncalves, Isabel S.
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p. 4618 - 4628
(2013/05/22)
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- Dimeric μ-oxo bridged molybdenum(vi) dioxo complexes as catalysts in the epoxidation of internal and terminal alkenes
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The preparation of the tridentate phenol based amine ligands HL1-HL4 is achieved via a convenient one-pot synthesis by reductive amination in quantitative yield in an autoclave under 7 bar H2 gas. Reaction of [MoO2(acac)2] and the corresponding ligand HLX (X = 1, 2 and 4) in methanol-H2O results in the formation of orange to red dimeric μ-oxo bridged [{MoO2(LX)}2(μ-O)] (X = 1, 2 and 4) complexes 1-3 in high yield and high purity. Complexes 1-3 are stable towards air and water. Both ligands coordinate via the phenolic O atom, the amine N atom and the third donor atom in the side chain (OMe for 1 and NMe 2 for 2 and 3) in a fac mode to the metal center. The molybdenum atoms are linked by a bridging μ-oxo moiety to each other as confirmed by X-ray diffraction analyses of complexes 2 and 3. All complexes have been tested in the epoxidation of several internal and terminal alkenes using TBHP as an oxidant. Depending on the nature of the substrate, the epoxides are obtained in moderate to good yields and high selectivities. In the epoxidation of cyclooctene a TOF = 467 h-1 with complex 1 has been observed, significantly higher compared to other dimeric complexes reported in the literature. In the more challenging epoxidation of styrene, complexes 1 and 2 have proven to be highly selective as only the formation of styrene oxide is observed. The OMe based complex 1 has also proven to be more active than the NMe2 based counterparts 2 and 3. The basic conditions induced by the NMe2 groups in complexes 2 and 3 lower their catalytic activity.
- Judmaier, Martina E.,Sala, Chris H.,Belaj, Ferdinand,Volpe, Manuel,Moesch-Zanetti, Nadia C.
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p. 2139 - 2149
(2013/10/08)
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- Dioxidomolybdenum(VI) complexes containing ligands with the bipyrrolidine backbone as efficient catalysts for olefin epoxidation
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Air-stable chiral dioxidomolybdenum(VI) complexes of the type [MoO 2(L)] (L = L12-; 1, L = L22-, 2) were prepared by the reaction of [MoO2Cl2] with the bis(phenol) ligands 1,4-bis(2-hydroxy-benzyl)-(S,S)-2,2′-bipyrrolidine [(S,S)-H2L1] and 1,4-bis(2-hydroxy-3,5-di-tert-butylbenzyl)-(S,S)-2,2′-bipyrrolidine [(S,S)-H2L2). They were characterized by NMR spectroscopy, mass spectrometry, elemental analysis, and single-crystal X-ray diffraction analysis, which revealed a distorted octahedral coordination geometry around the molybdenum(VI) center with a cis-α configuration. The Mo-Ooxo bond lengths are almost equal and vary only between 1.701 and 1.7091 A. Complexes 1 and 2 were found to be efficient and selective catalysts for various olefin epoxidation reactions. Catalyst loadings of 0.5 mol-%, the use of 2 equiv. of oxidant (tert-butyl hydroperoxide), as well as unchanged catalyst performance over three consecutive catalytic runs demonstrate the excellent stability of the catalysts. Various challenging substrates including 1-octene or limonene were converted selectively to their corresponding epoxides. However, no asymmetric induction was observed. The cis-α isomers of dioxidomolybdenum complexes with a chiral backbone exhibit higher catalytic epoxidation activity than the related cis-β complexes. Copyright
- Mayilmurugan, Ramasamy,Traar, Pedro,Schachner, Joerg A.,Volpe, Manuel,Moesch-Zanetti, Nadia C.
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p. 3664 - 3670
(2013/07/26)
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