- Epoxidation and hydroxylation reactions catalyzed by the manganese and iron complexes of 5,10,15,20-tetrakis(2,6-dimethoxyphenyl)porphyrin
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Manganese(III) and iron(III) complexes of 5,10,15,20-tetrakis-(2,6-dimethoxyphenyl)porphyrin (H2TDMeOPP) were tested as catalysts in the epoxidation of alkenes and in the hydroxylation of adamantane with H2O2 (in the prese
- Baciocchi, Enrico,Boschi, Tristano,Galli, Carlo,Lapi, Andrea,Tagliatesta, Pietro
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- Highly active Ga promoted Co-HMS-X catalyst towards styrene epoxidation reaction using molecular O2
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Atom efficient synthesis of various value added products has been focused as an intense research area after Kyoto protocol. Styrene epoxidation is a challenging reaction as styrene epoxide is an important monomer for large number of polymers. It has been found that surface acidity and redox property of the catalyst has a major contribution to the catalytic activity for oxidation reaction. In this study Co-HMS-X catalyst was prepared and characterized by BET surface area and porosity measurement, SAXS, SANS, FESEM, HRTEM, UV-vis spectra, FTIR, 29Si NMR, H2-TPR and NH3-TPD techniques. It is observed that 5 mol% Co-HMS-X showed highest catalytic activity for styrene epoxidation reaction using molecular O2 as an oxidant. Interestingly it is found that among three different dopant (Al, Ga, Tl), the Ga promoted Co-HMS-X catalyst (Si:Co:Ga = 100:5:1.25) showed highest catalytic activity in terms of styrene conversion (100%) and styrene epoxide selectivity (68%). The unusual trend of Al, Ga and Tl towards the activity of Co-HMS-X (5 mol%) catalyst has been discussed from the results obtained in the H 2-TPR and NH3-TPD study.
- Rahman, Sumbul,Santra, Chiranjit,Kumar, Rawesh,Bahadur, Jitendra,Sultana, Asima,Schweins, Ralf,Sen, Debasis,Maity, Sudip,Mazumdar,Chowdhury, Biswajit
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- Cp* iridium complexes give catalytic alkane hydroxylation with retention of stereochemistry
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A series of Cp Ir complexes can catalyze C-H oxidation, with ceric ammonium nitrate as the terminal oxidant and water as the source of oxygen. Remarkably the hydroxylation of cis-decalin and 1,4-dimethylcyclohexane proceeds with retention of stereochemistry. With H2O18, cis-decalin oxidation gave 18O incorporation into the product cis-decalol.
- Zhou, Meng,Schley, Nathan D.,Crabtree, Robert H.
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- Catalytic activity of Mn(III) and Fe(III) complexes of meso-tetra(n-propyl) porphyrin in oxidation of olefins: Meso-alkyl substituent in comparison with the alkenyl and aryl ones
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Catalytic activity of Mn(III) and Fe(III) complexes of meso-tetra(n-propyl) porphyrin, MnT(n-Pr)P(X) and FeT(n-Pr)P(X) (X = Cl, SCN, OAc) in oxidation of olefins with tetra-n-butylammonium periodate at room temperature has been studied. The influence of different parameters including the molar ratio of catalyst to imidazole, type of counter ion (X) and oxidative stability of metalloporphyrins on the efficiency of the catalysts was investigated. The results of competitive oxidation of cis- and trans-stilbene suggest the presence of a high-valent Mn-oxo as the predominant oxidant species in equilibrium with a six coordinate complex, MnT(n-Pr)P(ImH)(IO4) in the case of MnT(n-Pr)P(OAc). An unusual preference for trans-stilbene over cis-stilbene was observed in the reaction catalyzed by FeT(n-Pr)P(OAc). Control reaction indicated a significant cis- to trans-isomerization (81%) in oxidation of cis-stilbene catalyzed by FeT(n-Pr)P(OAc) which may explain the observed unusual cis to trans-stilbene oxide ratio. While oxidation of cyclooctene and styrene led to the exclusive formation of the corresponding epoxides, oxidation of cyclohexene gave 2-cyclohexe-1-ol and cyclohexene oxide as the products. However, the results of this study clearly demonstrate the key role played by the group substituted at the meso positions of metalloporphyrins on their catalytic activity, apart from the electron-donating or electron-withdrawing properties of the substituents.
- Zakavi, Saeed,Talebzadeh, Sadegh,Rayati, Saeed
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- Metal-cation-directed de novo assembly of a functionalized guest molecule in the nanospace of a metal-organic framework
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In this work, a new strategy is developed to encapsulate a metal-functionalized guest molecule into a metal-organic framework (MOF) via metal-cation-directed de novo assembly from the component fragments of the guest molecule. This strategy, as illustrate
- Li, Baiyan,Zhang, Yiming,Ma, Dingxuan,Ma, Tianliang,Shi, Zhan,Ma, Shengqian
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- Comparative study of catalytic activity of some biomimetic models of cytochrome P450 in oxidation of olefins with tetra-n-butylammonium periodate: Electron-rich Mn-porphyrins versus the electron-deficient ones
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Oxidation of a wide range of cyclic and acyclic olefins with tetra-n-butylammonium periodate shows different orders of catalytic activity for a series of electron-rich and electron-deficient Mn-porphyrins in oxidation of various alkenes. While the Mn(III) complex of meso-tetra(4-thiomethoxyphenyl) porphyrin, MnT(4-SCH3P)P(OAc), has the highest activity among the series, the β tetra-brominted derivative shows the lowest catalytic efficiency for the oxidation of the used olefins with the exception of cis- and trans-stilbene. The results clearly show that the electron-withdrawing effects of meso- and β-substituents may increase or decrease the catalytic activity of Mn-porphyrins in the case of different olefins.
- Zakavi, Saeed,Heidarizadi, Fatemeh,Rayati, Saeed
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- Oxygen atom transfer from a chiral oxaziridinium salt. Asymmetric epoxidation of unfunctionalized olefins
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The synthesis of an optically pure oxaziridinium salt from (1S,2R)-(+)- norephedrine and the study of the asymmetric oxygen transfer reactions from this reagent to unfunctionalized olefins are described.
- Bohe, Luis,Lusinchi, Marie,Lusinchi, Xavier
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- Use of titanium-containing silica catalysts prepared by rapid and straightforward method in selective oxidations
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A series of titanium-containing silica catalysts (Ti4/SiO 2) with small oligomeric Ti centres is obtained by impregnation of the air-stable and water-soluble tetranuclear Ti complex (NH4) 8[Ti4(C6H4O7) 4(O2)4]·8H2O onto commercial non-ordered mesoporous silica supports. Catalyst preparation is performed under very mild conditions, with no controlled atmosphere, following a simple, cheap, safe and sustainable methodology. Ti4/SiO2 catalysts can be used in the presence of TBHP or aqueous hydrogen peroxide and were tested in the selective oxidation of limonene, cyclohexene, trans-stilbene and 2,3,6-trimethylphenol. These catalysts showed performances fully comparable to (or even better than) those obtained with titanium-silicate materials prepared via conventional post-synthesis grafting approaches from organometallic precursors.
- Pirovano,Guidotti,Dal Santo,Psaro,Kholdeeva,Ivanchikova
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- NiO promoted CuO-NiO/SBA-15 composites as highly active catalysts for epoxidation of olefins
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In this paper, CuO-NiO supported on mesoporous silica SBA-15 was developed using the ultrasonic post-grafting method. The bi-metallic oxides were well-dispersed in very small sizes in the mesoporous channels, and the presence of NiO enhanced the surface content of CuO, leading to a redistribution of CuO and good dispersion of CuO nanoparticles, which were characterized by high-resolution transmission electron microscopy (HRTEM), XRD and N2 adsorption and desorption isotherm examination. Compared with the CuO/SBA-15 or NiO/SBA-15, the electron transfer that occurred between the two metal oxides and high dispersion of the active components improved the overall selective olefin oxidation.
- Tang, Yinhai,Gao, Hongyi,Yang, Mu,Wang, Ge,Li, Jie,Zhang, Huan,Tao, Zhang
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- Catalytic ferrocenyl sulfides for the asymmetric transformation of aldehydes into epoxides
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Six ferrocenyl sulfides, exhibiting planar and central chiralities, have been screened as a catalytic source of asymmetric sulfonium ylides. A one-pot reaction has been achieved, involving the addition of an aldehyde, benzyl bromide, 20% molar equivalent of the ferrocenyl sulfide, sodium iodide in a mixture of tert-butanol and water. The best results were observed with enantiopure sulfide 3a, bearing a tert-butyl group. Good yields of stilbene oxides were obtained, with enantiomeric excesses ranging from 74% to 94%. trans/cis-Diastereomeric ratios ranged from 60:40 to 86:14. The chiral sulfide was recovered. An unexpected case of stereoconvergence was observed with diastereoisomers 3a and 3b. A model is proposed to account for the asymmetric induction, based on a conformation locked by the tert-butyl group and the interplay of planar and remote central chiralities.
- Miniere, Stephanie,Reboul, Vincent,Metzner, Patrick,Fochi, Mariafrancesca,Bonini, Bianca Flavia
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- The development and evaluation of a continuous flow process for the lipase-mediated oxidation of alkenes
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We report the use of an immobilised form of Candida antarctica lipase B, Novozym 435, in a preliminary investigation into the development of a continuous flow reactor capable of performing the chemo-enzymatic oxidation of alkenes in high yield and purity,
- Wiles, Charlotte,Hammond, Marcus J.,Watts, Paul
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- First structurally characterized optically active mononuclear Mn(IV) complex: Synthesis, crystal structure and properties of [MnIVL 2] {H2L = S-(-)-2-[(2-hydroxy-1-phenylethylimino)methyl] phenol}
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The reaction of Mn(CH3COO)2·4H2O with H2L {H2L = S-(-)-2-[(2-hydroxy-1-phenylethylimino) methyl]phenol} in the presence of air afforded dark brown crystals of [Mn IVL2], 1. Compo
- Pradeep, Chullikkattil P.,Htwe, Tin,Zacharias, Panthapally S.,Das, Samar K.
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- Preparation of Optically Active Epoxides Via Sulfur Ylides. Origin of the Chiral Induction.
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The sulfonium ylide derived from (1R, 2S, 3R, 5S)-2,3-dibenzyl-1,8,8-trimethyl-3-thianiumbicyclooctane perchlorate 6 (prepared from (1R,3S)-(+)-camphoric acid) transfers its benzylidene group to some carbonyl compounds with ee's approaching enantiomeric purity.It is suggested that in this system the chiral induction is due to the facial selectivity at the ylide rather than the carbonyl carbon.
- Breau, L.,Durst, T.
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- Asymmetric epoxidation catalyzed by esters of α-hydroxy-8-oxabicyclo[3.2.1]octan-3-one
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Several esters of α-hydroxy-8-oxabicyclo[3.2.1]octan-3-one were prepared and tested as catalysts for alkene epoxidation by Oxone.
- Armstrong, Alan,Moss, William O.,Reeves, Jonathan R.
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- Photocatalytic asymmetric epoxidation oftrans-stilbene with manganese-porphyrin/graphene-oxide nanocomposite and molecular oxygen: axial ligand effect
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An efficient, visible light-driven manganese-porphyrin photocatalyst was developed for the asymmetric epoxidation by molecular oxygen under mild conditions. A Mn-porphyrin complex covalently bonded to graphene oxide (GO) sheets was synthesized and characterized, where chirality is induced by enantiopurel-tartrate (tart), acting either as a counter ion or axial ligand. The heterogeneous photocatalyst GO-[Mn(T2PyP)(tart)](tart) showed an excellent epoxide selectivity of 100% toward the enantioselective epoxidation oftrans-stilbene (ee 100%) in the presence of imidazole under irradiation with a white LED light source. An imidazole molecule hydrogen bonded to the high-valent manganese-oxo intermediate and (tartrate)?counter ion seems to be responsible for substantially enhancing the enantioselectivity of the catalyst. Also, an imidazole molecule coordinated to the metal centre is probably involved in the increased catalytic activity. With immobilized manganese porphyrin as photocatalyst, significant improvements in rate and enantioselectivity were attained by simply adding imidazole as an axial ligand and a hydrogen bond donor intrans-stilbene epoxidation. At the end of the reaction, GO-[Mn(T2PyP)(tart)](tart) was readily separated by filtration and reused for subsequent runs without any loss of its activity and enantioselectivity, resulting in a total turnover number (TON) of 3000.
- Ahadi, Elahe,Hosseini-Monfared, Hassan,Janiak, Christoph,Spie?, Alex
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- Availability and reactivity of concentrated dimethyldioxirane solutions in solvents other than acetone
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Four to five-fold increase in concentration or the possibility of isolation in 'acetone-free' medium has become possible for dimethyldioxirane solutions in CH2Cl2, CHCl3, CCl4 and CFCl3 by employing a
- Gibert, Mariona,Ferrer, Marta,Saenchez-Baeza, Francisco,Messeguer, Angel
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- Flexible and Hierarchical Metal–Organic Framework Composites for High-Performance Catalysis
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The development of porous composite materials is of great significance for their potentially improved performance over those of individual components and extensive applications in separation, energy storage, and heterogeneous catalysis. Now mesoporous metal–organic frameworks (MOFs) with macroporous melamine foam (MF) have been integrated using a one-pot process, generating a series of MOF/MF composite materials with preserved crystallinity, hierarchical porosity, and increased stability over that of melamine foam. The MOF nanocrystals were threaded by the melamine foam networks, resembling a ball-and-stick model overall. The resulting MOF/MF composite materials were employed as an effective heterogeneous catalyst for the epoxidation of cholesteryl esters. Combining the advantages of interpenetrative mesoporous and macroporous structures, the MOF/melamine foam composite has higher dispersibility and more accessibility of catalytic sites, exhibiting excellent catalytic performance.
- Huang, Ning,Drake, Hannah,Li, Jialuo,Pang, Jiandong,Wang, Ying,Yuan, Shuai,Wang, Qi,Cai, Peiyu,Qin, Junsheng,Zhou, Hong-Cai
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- Preferential azido bridging regulating the structural aspects in cobalt(III) and copper(II)-Schiff base complexes: Syntheses, magnetostructural correlations and catalytic studies
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A tridentate NNO donor Schiff base ligand [(1Z,3E)-3-((pyridin-2-yl) methylimino)-1-phenylbut-1-en-1-ol = LH] in presence of azide ions coordinates with cobalt(II) and copper(II) ions giving rise to three new coordination complexes [Co2(L)2(μ1,1-N3) 2(N3)2] (1), [Cu2(L) 2(μ1,3-N3)]·ClO4 (2) and [(μ1,1-N3)2Cu5(μ-OL) 2(μ1,1-N3)4(μ1,1,1- N3)2]n (3). The complexes have been characterized by elemental analysis, FT-IR, UV-Vis spectral studies, and single crystal X-ray diffraction studies. These complexes demonstrate that under different synthetic conditions the azide ions and the Schiff base ligand (LH) show different coordination modes with cobalt(II) and copper(II) ions, giving rise to unusual dinuclear and polynuclear species (1, 2 and 3) whose structural variations are discussed. Magneto-structural correlation for the very rare singly μ1,3-N3 bridged CuII-Schiff base dinuclear species (2) has been studied. In addition, the catalytic properties of 1 for alkene oxidation and the general catalase-like activity behavior of 2 have been discussed.
- Ray, Aurkie,Rosair, Georgina M.,Pilet, Guillaume,Dede, Bülent,Gómez-García, Carlos J.,Signorella, Sandra,Bellú, Sebastián,Mitra, Samiran
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- Rapid and highly selective epoxidation of alkenes by tetrabutylammonium monopersulfate in the presence of manganese meso-tetrakis(pentafluorophenyl)porphyrin and tetrabutylammonium salts or imidazole co-catalysts
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Epoxidation of various alkenes in low to high yields (29-100%) and good to excellent selectivities (75-100%) was performed with tetrabutylammonium monopersulfate in the presence of meso-tetrakis(pentafluorophenyl)porphyrin as catalyst and tetrabutylammonium acetate or fluoride or imidazole as co-catalysts in CH2Cl2, in less than 10 min at room temperature (~25 °C).
- Mohajer, Daryoush,Solati, Zahra
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- A host-guest epoxidation catalyst with enhanced activity and stability
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A porphyrin-capped molecular clip epoxidises olefins, depending on the axial ligand used, with enhanced activity or stability.
- Elemans,Bijsterveld,Rowan,Nolte
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- Supported manganese porphyrin catalysts as P450 enzyme mimics for alkene epoxidation
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Manganese porphyrin catalysts have been supported on Merrifield and Argogel resins and their catalytic activity has been demonstrated in alkene epoxidation. Furthermore, recyclability studies have shown that the reuse of the Merrifield-supported catalyst can be achieved three times with minimum loss of activity.
- Brulé, Emilie,De Miguel, Yolanda R
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- A route to magnetically separable nanocatalysts: Combined experimental and theoretical investigation of alkyl substituent role in ligand backbone towards epoxidation ability
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We have prepared two chiral Schiff base ligands, H2L1 and H2L2, and one achiral Schiff base ligand, H2L3, by treating 2,6-diformyl-4-methylphenol separately with (R)-1,2-diaminopropane, (R)
- Chattopadhyay, Tanmay,Chakraborty, Aratrika,Dasgupta, Sanchari,Dutta, Arnab,Menéndez, M. Isabel,Zangrando, Ennio
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- Olefin epoxidation with bis(trimethylsilyl) peroxide catalyzed by inorganic oxorhenium derivatives. Controlled release of hydrogen peroxide
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The replacement of organometallic rhenium species (e.g., CH3ReO3) by less expensive and more readily available inorganic rhenium oxides (e.g., Re2O7, ReO3(OH), and ReO3) can be accomplished using bis(trimethylsilyl) peroxide (BTSP) as oxidant in place of aqueous H2O2. Using a catalytic amount of a proton source, controlled release of hydrogen peroxide helps preserve sensitive peroxorhenium species and enables catalytic turnover to take place. Systematic investigation of the oxorhenium catalyst precursors, substrate scope, and effects of various additives on olefin epoxidation with BTSP are reported in this contribution.
- Yudin,Chiang,Adolfsson,Copéret
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- Evaluation of some 5-pyrazolone-based copper(II) complexes as catalysts for the oxidation of trans-stilbene
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[Figure not available: see fulltext.] The catalytic properties of the azo- and bisazo-5-pyrazolone-based three copper(II) complexes have been studied. Heating under reflux with or without ultrasonic irradiation was applied for the different equivalent amounts of three copper(II) catalysts (0.6 and 1.0 mol %) in ethyl acetate. It has been shown that all pyrazolone-based copper(II) complexes are active for catalytic oxidation of trans-stilbene in the presence of tert-butyl hydroperoxide as the oxidant, providing high selectivity and good conversion values. Heating was applied to the different solvents: chloroform, tetrahydrofuran, N,N-dimethylformamide, and dioxane. All catalysts can be safely used near to the boiling point of the oxidant without decomposition and the efficacy of ethyl acetate under conventional heating and heating–ultrasonic conditions has been determined. Heating–ultrasonic conditions and 1.0 mol % of catalysts gave higher conversion than conventional heating and 0.6 mol % of catalysts. A mechanism is proposed for the catalytic oxidation of trans-stilbene with tert-butyl hydroperoxide.
- Bagdatli, Emine
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- In the Presence of Imidazole, Iron- and Manganese-prophyrins catalyse the Epoxidation of Alkenes by Alkyl Hydroperoxides
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In the presence of imidazole, Mn(TPP)(Cl) and Fe(TPP)(Cl) (TPP = tetraphenylporphyrin) catalyse the epoxidation of styrene, cyclohexene, 2-methylhept-2-ene, and stilbene by cumyl hydroperoxide; in the case of Mn(TPP)(Cl), a transient species, characterize
- Mansuy, Daniel,Battioni, Pierrette,Renaud, Jean-Paul
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- Ni (II) schiff base complex immobilized on graphene oxide nano-sheets catalyzed epoxidation of alkenes
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Ni (II) schiff base complex was synthesized by the reaction of nickel acetate tetrahydrate with N, N’-Bis(2,4-di-hydroxybenzaldehyde)-1,2-cyclohexanediamine and supported on modified grapheme oxide nano-sheets using 3-chloropropyltrimethoxysilane as a rea
- Allahresani, Ali
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- Epoxidation of alkenes with molecular oxygen catalyzed by a manganese porphyrin-based metal-organic framework
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The flexible nature of reticular assemblies and high specific surfaces ofmetalorganic frameworks (MOFs) offers new opportunities for the design of heterogeneous catalysts capable of industrially relevant reactions. We demonstrate the first instance of alkene epoxidation at mild conditions using molecular oxygen by a manganese porphyrin containing MOF, MOF-525-Mn [Zr6O4 (OH)4 (MgC48H24O8N4Cl)3]. This zirconium MOF with a manganese porphyrin catalyst shows minimal deactivation over long periods and maintains its structure and high activity aftermultiple catalytic cycles. Kinetic studies of styrene epoxidation are in agreement with theoretical and experimental studies of homogeneous reactions with the same porphyrin unit, suggesting that the heterogeneous catalyst operates according to a similar mechanism as its homogeneous counterpart.
- Brown, Jonathan W.,Nguyen, Quyen T.,Otto, Trenton,Jarenwattananon, Nanette N.,Gl?ggler, Stefan,Bouchard, Louis-S.
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- Olefin epoxidation with H2O2 in the presence of Mn(II) dicarboxylate coordination polymer catalysts
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The Mn(II) dicarboxylate coordination polymers [Mn(μ-terephthalate) (H2O)2] n, [Mn(μ-oxalate)(H 2O)2] n, and [Mn(μ-d-(-)-tartrate)] n were prepared in water and characterized by FT-IR spectroscopy and CHN analysis. Particles of the terephthalate catalyst were also synthesized, by reaction of terephthalic acid and MnCl2?4H2O by a sonochemical method. The catalytic potential of these coordination polymers as slow-release sources of catalytically active Mn species was tested in the oxidation of cyclooctene to its epoxide in acetonitrile, using hydrogen peroxide as oxygen source. For the terephthalate species the catalytic activity was found to increase with increasing dielectric constant and dipole moment of the solvent (being highest in acetonitrile), with reaction temperature to a maximum at 60 °C, and with an imidazole co-catalyst (highest activity found for a imidazole-to-catalyst molar ratio of 20:1). Good activity with more than 64% conversion in 24 h was obtained for epoxidation of cyclooctene and cyclohexene, whereas low yields only were obtained from aryl-substituted olefins. Some exo versus endo regioselectivity was found for norbornene.
- Hosseini Monfared, Hassan,Mohajeri, Azar,Morsali, Ali,Janiak, Christoph
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- The catalytic function of a silica gel-immobilized Mn(II)-hydrazide complex for alkene epoxidation with H2O2
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An efficient and highly selective heterogeneous catalyst was developed by immobilization of a manganese complex on an inorganic support to yield (silica gel)-O2(EtO)Si-L1-Mn(HL2) [(L1) - modified salicylaldiminato and H2L2(E)- N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide]. Mn(II) has been anchored on the surface of functionalized silica by means of N,O-coordination to the covalently Si-O bound modified salicylaldiminato Schiff base ligand. The prepared material (silica gel)-O2(EtO)Si-L1-Mn(HL 2), was characterized by elemental and thermogravimetric analyses (TGA and DTA), UV-vis and FT-IR spectroscopy. This new material is demonstrated to be a very active catalyst in clean epoxidation reactions using a combined oxidant of aqueous hydrogen peroxide and actonitrile in the presence of aqueous sodium hydrogencarbonate. The effects of reaction parameters such as solvent, NaHCO3 and oxidant in the epoxidation of cis-cyclooctene were investigated. Cycloalkenes were oxidized efficiently to their corresponding epoxide with 87-100% selectivity in the presence of this catalyst. This catalytic system showed also good activities in the epoxidation of linear alkenes. The obtained results show that this catalyst is a robust and stable heterogeneous catalyst which can be recovered quantitatively by simple filtration and reused multiple times without loss of its activity.
- Ghorbanloo, Massomeh,Monfared, Hassan Hosseini,Janiak, Christoph
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- Temperature effect on the epoxidation of olefins by an iron(III) porphyrin complex and tert-alkyl hydroperoxides
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An electron-deficient iron porphyrin complex catalyzes the epoxidation of olefins by tert-alkyl hydroperoxides via radical-free oxidation reactions in aprotic solvent; the epoxidation reactions were markedly influenced by reaction temperature and high yields of epoxide products were obtained with retention of stereospecificity at low temperature.
- Nam,Oh,Mi Hee Lim,Choi,Han,Jhon
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- Salicylaldoxime and salen containing imidazolium ionic liquids for biphasic catalysis and metal extractions
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Imidazolium salts containing salicylaldoxime or salen ligands readily form ionic metal complexes with copper and manganese; hence offering applications in metal extractions and biphasic catalysis.
- Naik, Prashant U.,McManus, Gregory J.,Zaworotko, Michael J.,Singer, Robert D.
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- Too Many Cooks Spoil the Broth - Variable Potencies of Oxidizing Mn Complexes of a Hexadentate Carboxylato Ligand
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Given the hexadenticity of the monoanionic ligand in the procatalyst [Mn(tpena)(H2O)](ClO4) {tpena- = N,N,N′-tris(2-pyridylmethyl)ethylenediamine-N′-acetate}, it is perhaps surprising that this complex can catalyze the epoxidation of alkenes. When peracetic acid is used as terminal oxidant, the selectivity and rates of reactions are comparable with those reported for the manganese complexes of the commonly employed neutral tetradentate N4 ligands under analogous conditions. Cyclooctene conversion rates are similar when tert-butyl hydroperoxide (TBHP) is used; however, the selectivity is greatly diminished. In the absence of organic substrates, [MnII(tpena)]+ catalyzes water oxidation by TBHP (initial rate ca. 23 mmol/h when [Mn] = 0.1 mM, at room temp.). To explain the variations in the selectivity of catalytic epoxidations and the observation of competing water oxidation, we propose that several metal-based oxidants (the "cooks") can be generated from [MnII(tpena)]+. These embody different potencies. The most powerful, and hence least selective, is proposed to be the isobaric isomer of [MnIV2(O)2(tpena)2]2+, namely an oxylic radical complex, [(tpena)MnIII(μ2-O)MnIV(O·)(tpena)]2+. The formation of this species depends on the catalyst concentration, and it is favoured when TBHP is used as the terminal oxidant. The generation of the less potent [MnIV(O)(tpena)]+, which we propose as the direct oxidant in epoxidation reactions, is favoured in non-aqueous solutions when peracetic acid is used as the terminal oxidant. A manganese(II) complex of a hexadentate ligand catalyzes epoxidation. However, reaction conditions are critical since several metal-based oxidants with varying potencies can be generated. This observation is probably general for related catalysts, and consequences include decreased selectivity and competing water oxidation.
- Deville, Claire,Finsel, Maik,De Sousa, David P.,Szafranowska, Barbara,Behnken, Julian,Svane, Simon,Bond, Andrew D.,Seidler-Egdal, Rune Kirk,McKenzie, Christine J.
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- Homochiral Metal-Organic Frameworks for Enantioselective Separations in Liquid Chromatography
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Selective separation of enantiomers is a substantial challenge for the pharmaceutical industry. Chromatography on chiral stationary phases is the standard method, but at a very high cost for industrial-scale purification due to the high cost of the chiral stationary phases. Typically, these materials are poorly robust, expensive to manufacture, and often too specific for a single desired substrate, lacking desirable versatility across different chiral analytes. Here, we disclose a porous, robust homochiral metal-organic framework (MOF), TAMOF-1, built from copper(II) and an affordable linker prepared from natural l-histidine. TAMOF-1 has shown to be able to separate a variety of model racemic mixtures, including drugs, in a wide range of solvents of different polarity, outperforming several commercial chiral columns for HPLC separations. Although not exploited in the present article, it is worthy to mention that the preparation of this new material is scalable to the multikilogram scale, opening unprecedented possibilities for low-energy chiral separation at the industrial scale.
- Corella-Ochoa, M. Nieves,Tapia, Jesús B.,Rubin, Heather N.,Lillo, Vanesa,González-Cobos, Jesús,Nú?ez-Rico, José Luis,Balestra, Salvador R.G.,Almora-Barrios, Neyvis,Lledós, Marina,Gu?ll-Bara, Arnau,Cabezas-Giménez, Juanjo,Escudero-Adán, Eduardo C.,Vidal-Ferran, Anton,Calero, Sofiá,Reynolds, Melissa,Martí-Gastaldo, Carlos,Galán-Mascarós, José Ramón
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- Chiral Stationary Phase Derived from (-)-anti Head-to-Head Coumarin Dimer: Preparation, Characterization, and Chiral Recognition Ability
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A monoamide derived from (-)-anti head-to-head coumarin dimer with propylamine has been successfully bonded to silica gel (Lichrospher 100 NH2: Merck) through amide linkage to prepare CSP-1.Another monoamide derivative CSP-2 was prepared by direct nucleophilic opening of one lactone ring of (-)-CD by Lichospher 100 NH2, followed by hydrolysis of the other lactone.CSP-1 and CSP-2 showed high enantioselectivity to trans-stilbene oxide with separation factors (α) at 2.42 and 2.46, respectively, and the (-)-isomer eluted first.The capacity factor (k') and α decrease with increasing polarity of the eluent (hexane/2-propanol), indicating that hydrogen bonding plays important role in chiral recognition.CSP-3, obtained by ligand exchange of CSP-2 with CuSO4(aq), resolved DL-tryptophan, DL-tyrosine, and DL-phenylalanine (α = kD'/KL' = 1.14-1.33), which all contain aromatic chromophore.The stability difference of the ternary complexes formed with D-isomer and L-isomer is explained by steric hindrance and aromatic ?-? interactions.
- Chen, Yun,Shiao, Ming-Tang
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- Epoxidations catalyzed by manganese(v) oxo and lmido complexes: Role of the oxidant mn oxo (lmido) intermediate
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The manganese(V) oxo complex (TBP8Cz)Mnv(O) (1) is shown to catalyze the epoxidation of alkenes with a series of iodosylarenes (ArIO) as oxidants. Competition experiments reveal that the identity of ArIO influences the product ratios, implicating an unusual coordinated oxo-metal-ArIO intermediate (1-OIAr) as the active catalytic species. The isoelectronic manganese(V) imido complex (TBP8Cz)Mnv(NMes) (2) does not participate in NR transfer but does catalyze epoxidations with ArIO as the O-atom source, suggesting a mechanism similar to that seen for 1. Direct evidence (ESIMS) is obtained for 1-OIMes.
- Leeladee, Pannee,Goldberg, David P.
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- Efficient synthesis of epoxides from vicinal diols via cyclic sulfates
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Reaction of cyclic sulfates of vic-diols with sodium hydroxide in THF-MeOH produced the corresponding epoxides in excellent isolated yields at room temperature. Cyclic sulfates of trans-diols gave cis-epoxides, and cyclic sulfates of cis-diols afforded tr
- Jang,Joo,Cho
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- Laser flash photolysis formation and direct kinetic studies of manganese(V)-oxo porphyrin intermediates
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Irradiation of porphyrin-manganese(III) perchlorate complexes in acetonitrile with 355 nm laser light gave MnV-oxo intermediates that were characterized by their UV-vis spectra and reactivities. The MnV-oxo species of tetrakis(pentaf
- Zhang, Rui,Newcomb, Martin
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- Terpenyl tellurides - Synthesis and application in asymmetric epoxidation
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This work presents a synthesis of new group of unsymmetrical chiral tellurides obtained in the reaction of sodium methanetellurolate or sodium benzenetellurolate with appropriate terpenyl tosylates from p-menthane, carane, and pinane systems. Additionally, symmetrical diterpenyl tellurides were prepared according to our recently published method using sodium telluride and terpenyl tosylates. Methyl terpenyl, phenyl terpenyl, and diterpenyl tellurides were successfully used in tellurium ylide-mediated asymmetric epoxidation reaction. The best result of asymmetric epoxidation was obtained for dicaranyl telluride (d.r. cis:trans 11:89, e.r. trans 84:16).
- ?cianowski, Jacek,Banach, Anna,Pacu?a, Agata J.
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- Heterogenization of three homogeneous catalysts: A comparative study as epoxidation catalyst
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Three homogeneous catalysts, MnL1Cl·2H2O(1.2 H2O) (HmC-1), FeL1(NO3)·3H2O (HmC-2) and CoL1(NO3)-·2H2O (HmC-3) [L1 = N,N′-ethylenebis(3-formyl-5-m
- Adhikary, Jaydeep,Guha, Averi,Chattopadhyay, Tanmay,Das, Debasis
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- MONOOXYGEN TRANSFER POTENTIAL OF THE TRANSANNULAR OZONIDE OF 9-TERT-BUTYL-10-METHYLANTHRACENE
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The efficiency of oxygen transfer from the transannular ozonide 1 to several organic substrates was investigated.The effiency was estimated to be as high as 90percent in the case of Ph3P as the substrate.
- Ito, Yoshikatsu,Matsuura, Akira,Matsuura, Teruo
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- Carboranycarboxylate Complexes as Efficient Catalysts in Epoxidation Reactions
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This work presents the first examples of carboranylcarboxylate complexes as precatalysts in epoxidation reactions with the use of peracetic acid as the oxidant. The manganese [Mn(μ-H2O)(1-CH3-2-CO2-1,2-closo-C2B10H10)2]n·(H2O)n (1), [Mn2(1-CH3-2-CO2-1,2-closo-C2B10H10)4(2,2′-bpy)2] (2, bpy = bipyridine), [Mn(1-CH3-2-CO2-1,2-closo-C2B10H10)2(bpm)]n (3, bpm = bipyrimidine), and [Mn(1-CH3-2-CO2-1,2-closo-C2B10H10)2(2,2′-bpy)2] (4) complexes and the cobalt [Co2(μ-H2O)(1-CH3-2-CO2-1,2-closo-C2B10H10)4(thf)4] (6) complex, all containing the carboranylcarboxylic 1-CH3-2-CO2H-1,2-closo-C2B10H10 (LH) ligand, together with Mn3(OAc)6(2,2′-bpy)2 (5) displayed good performance with high conversions and selectivity values in short reaction times, in most cases. This work highlights that the coordination of the carboranylcarboxylic ligand to the metal ions is crucial to the performance of the complexes as catalysts.
- Fontanet, Mònica,Rodríguez, Montserrat,Vi?as, Clara,Teixidor, Francesc,Romero, Isabel
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- A mesoporous NNN-pincer-based metal-organic framework scaffold for the preparation of noble-metal-free catalysts
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Through topology-guided synthesis, a Zr-based mesoporous MOF was successfully constructed, adopting a β-cristobalite-type structure. The MOF is embedded with well-arranged terpyridine coordination sites for facile post-synthetic metalation, and can be effectively used as a general scaffold for the preparation of noble-metal-free catalysts. For instance, the scaffolded metal@MOF material exhibits highly efficient catalytic activity for alkene epoxidation and arene borylation.
- Zhang, Yingmu,Li, Jialuo,Yang, Xinyu,Zhang, Peng,Pang, Jiandong,Li, Bao,Zhou, Hong-Cai
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- Efficient epoxidation of alkenes with sodium periodate catalyzed by manganese porphyrins in ionic liquid: Investigation of catalyst reusability
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In the present work, efficient epoxidation of alkenes with sodium periodate catalyzed by tetraphenylporphyrinatomanganese(III) chloride, Mn(TPP)Cl, and octabromotetraphenylporphyrinatomanganese(III) chloride, Mn(Br 8TPP)Cl, using (1-n-butyl-3-m
- Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Hajian, Robabeh
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- Computer-assisted discovery of novel amino acid derived sulfides for enantioselective epoxidation of aldehydes
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With the aid of molecular modeling, thiazolidine derivatives have been designed as catalysts for epoxidation of aldehydes. Accessible from amino acids, the thiazolidine derivatives can be synthesized in both enantiomeric forms and with a diverse array of substituents. A representative member, (S)-N-tert-butoxycarbonyl-2,2-dimethyl-4-isopropyl thiazolidine, of the thiazolidine family has been prepared, and it has been shown to catalyze the formation of trans-stilbene oxide with high enantioselectivity. Experimental and theoretical characterization has allowed the evaluation of the factors affecting enantioselectivity, facilitating the design of second-generation thiazolidines and other chiral sulfides as epoxidation catalysts.
- Myllym?ki, Vesa T.,Lindvall, Mika K.,Koskinen, Ari M. P.
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- First chiral selenium ylides used for asymmetric conversion of aldehydes into epoxides
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Enantioenriched selenonium ylides have been generated by addition of benzyl bromide to C2 symmetric (2R,5R)2,5-dimethylselenolane in the presence of NaOH, and subsequently reacted with a variety of aldehydes to give oxiranes with excellent enantiomeric excesses (a catalytic version has been achieved); also, an aliphatic cyclic hypervalent dibromoselenurane structure has been demonstrated by X-ray analysis.
- Takada,Metzner,Philouze
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- Catalytic efficacy of copper(II)and cobalt(III)schiff base complexes in alkene epoxidation
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A potentially hexadentate N2O4 donor Schiff base ligand N,N-bis(5-bromo-3-methoxysalicylideneimino)-1,3- diaminopropane (H2L1) has been used to synthesize two mononuclear coordination complexes [Cu(L1)]H2O (1) and [Co(L1)(HL2)]ClO4CH3CN (2). The cobalt co
- Maiti, Monami,Sadhukhan, Dipali,Thakurta, Santarupa,Zangrando, Ennio,Pilet, Guillaume,Signorella, Sandra,Bellu, Sebastian,Mitra, Samiran
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- Asymmetric Epoxidation of Unfunctionalized Olefins Using Novel Chiral Dihydroisoquinolinium Salts as Organocatalysts
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Abstract: Two new non-racemic chiral dihydroisoquinolinium salts with N-substituents bulkier than a methyl group have been synthesized from (1S,2R)-norephedrine. These salts were used to catalyze asymmetric epoxidation of a series of prochiral olefins. One of the two new catalysts provided higher enantioselectivities (up to 66% ee) than the reference salt containing an N-methyl substituent.
- Ali, K. Ben
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p. 638 - 646
(2021/06/02)
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- Effect of the Ligand Backbone on the Reactivity and Mechanistic Paradigm of Non-Heme Iron(IV)-Oxo during Olefin Epoxidation
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The oxygen atom transfer (OAT) reactivity of the non-heme [FeIV(2PyN2Q)(O)]2+ (2) containing the sterically bulky quinoline-pyridine pentadentate ligand (2PyN2Q) has been thoroughly studied with different olefins. The ferryl-oxo complex 2 shows excellent OAT reactivity during epoxidations. The steric encumbrance and electronic effect of the ligand influence the mechanistic shuttle between OAT pathway I and isomerization pathway II (during the reaction stereo pure olefins), resulting in a mixture of cis-trans epoxide products. In contrast, the sterically less hindered and electronically different [FeIV(N4Py)(O)]2+ (1) provides only cis-stilbene epoxide. A Hammett study suggests the role of dominant inductive electronic along with minor resonance effect during electron transfer from olefin to 2 in the rate-limiting step. Additionally, a computational study supports the involvement of stepwise pathways during olefin epoxidation. The ferryl bend due to the bulkier ligand incorporation leads to destabilization of both (Formula presented.) and (Formula presented.) orbitals, leading to a very small quintet–triplet gap and enhanced reactivity for 2 compared to 1. Thus, the present study unveils the role of steric and electronic effects of the ligand towards mechanistic modification during olefin epoxidation.
- Biswas, Jyoti Prasad,Ansari, Mursaleem,Paik, Aniruddha,Sasmal, Sheuli,Paul, Sabarni,Rana, Sujoy,Rajaraman, Gopalan,Maiti, Debabrata
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supporting information
p. 14030 - 14039
(2021/05/11)
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- Nonheme manganese(III) complexes for various olefin epoxidation: Synthesis, characterization and catalytic activity
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Three mononuclear imine-based non-heme manganese(III) complexes with tetradentate ligands which have two deprotonated phenolate moieties, ([(X2saloph)Mn(OAc)(H2O)], 1a for X = Cl, 1b for X = H, and 1c for X = CH3, saloph = N,N-o-phenylenebis(salicylidenaminato)), were synthesized and characterized by 1H NMR, 13C NMR, ESI-Mass and elemental analysis. MnIII complexes catalysed efficiently various olefin epoxidation reactions with meta-chloroperbenzoic acid (MCPBA) under the mild condition. MnIII complexes 1a and 1c with the electron-withdrawing group -Cl and electron-donating group –CH3 showed little substituent effect on the epoxidation reactions. Product analysis, Hammett study and competition experiments with cis- and trans-2-octene suggested that MnIV = O, MnV = O, and MnIII-OOC(O)R species might be key oxidants in the epoxidation reaction under this catalytic system. In addition, the use of PPAA as a mechanistic probe demonstrated that Mn-acylperoxo intermediate (MnIII-OOC(O)R) 2 generated from the reaction of peracid with manganese complexes underwent both the heterolysis and the homolysis to produce MnV = O (3) or MnIV = O species (4). Moreover, the MnIII-OOC(O)R 2 species could react directly with the easy-to-oxidize substrate to give epoxide, whereas the species 2 might not be competent to the difficult-to-oxidize substrate for the epoxidation reaction.
- Lee, Sojeong,Park, Soyoung,Lee, Myoung Mi,Lee, Jiyoung,Kim, Cheal
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- Radical-mediated aerobic oxidation of substituted styrenes and stilbenes
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A 2,2-azobis(isobutyronitrile)-catalyzed oxidative cleavage of alkenes with molecular oxygen as the oxidant was described. Carbonyl compounds and oxiranes were obtained in moderate yield under mild conditions. This study provided useful insights into the mechanism of aerobic oxidative cleavage of alkenes.
- Aman, Hasil,Chiu, Wei-Hua,Chuang, Gary Jing,Liu, Pin-Heng
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supporting information
p. 20103 - 20106
(2021/12/02)
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- Construction of an Asymmetric Porphyrinic Zirconium Metal-Organic Framework through Ionic Postchiral Modification
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Herein, one kind of neutral chiral zirconium metal-organic framework (Zr-MOF) was reported from the porphyrinic MOF (PMOF) family with a metallolinker (MnIII-porphyrin) as the achiral polytopic linker [free base tetrakis(4-carboxyphenyl)porphyrin] and chiral anions. Achiral Zr-MOF was chiralized through the exchange of primitive anions with new chiral organic anions (postsynthetic exchange). This chiral functional porphyrinic MOF (CPMOF) was characterized by several techniques such as powder X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, 1H NMR, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller measurements. In the resulting structure, there are two active metal sites as Lewis acid centers (Zr and Mn) and chiral species as Br?nsted acid sites along with their cooperation as nucleophiles. This CPMOF shows considerable bimodal porosity with high surface area and stability. Additionally, its ability was investigated in asymmetric catalyses of prochiral substrates. Interactions between framework chiral species and prochiral substrates have large impacts on the catalytic ability and chirality induction. This chiral catalyst proceeded asymmetric epoxidation and CO2 fixation reactions at lower pressure with high enantioselectivity due to Lewis acids and chiral auxiliary nucleophiles without significant loss of activity up to the sixth step of consecutive cycles of reusability. Observations revealed that chiralization of Zr-MOF could happen by a succinct strategy that can be a convenient method to design chiral MOFs.
- Berijani, Kayhaneh,Morsali, Ali
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p. 206 - 218
(2021/01/11)
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- Proton Switch in the Secondary Coordination Sphere to Control Catalytic Events at the Metal Center: Biomimetic Oxo Transfer Chemistry of Nickel Amidate Complex
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High-valent metal-oxo species are key intermediates for the oxygen atom transfer step in the catalytic cycles of many metalloenzymes. While the redox-active metal centers of such enzymes are typically supported by anionic amino acid side chains or porphyrin rings, peptide backbones might function as strong electron-donating ligands to stabilize high oxidation states. To test the feasibility of this idea in synthetic settings, we have prepared a nickel(II) complex of new amido multidentate ligand. The mononuclear nickel complex of this N5 ligand catalyzes epoxidation reactions of a wide range of olefins by using mCPBA as a terminal oxidant. Notably, a remarkably high catalytic efficiency and selectivity were observed for terminal olefin substrates. We found that protonation of the secondary coordination sphere serves as the entry point to the catalytic cycle, in which high-valent nickel species is subsequently formed to carry out oxo-transfer reactions. A conceptually parallel process might allow metalloenzymes to control the catalytic cycle in the primary coordination sphere by using proton switch in the secondary coordination sphere.
- Kim, Soohyung,Jeong, Ha Young,Kim, Seonghan,Kim, Hongsik,Lee, Sojeong,Cho, Jaeheung,Kim, Cheal,Lee, Dongwhan
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supporting information
p. 4700 - 4708
(2021/02/12)
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- Self-assembled ionic liquid based organosilica-titania: A novel and efficient catalyst for green epoxidation of alkenes
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A novel titanium-containing self-assembled ionic liquid based hybrid organic-inorganic organosilica (Ti-ILOS) was prepared, characterized and applied as highly effective catalyst for the green epoxidation of alkenes in the presence of hydrogen peroxide as
- Yari, Omolbanin,Elhamifar, Dawood,Shaker, Masoumeh
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- Substituent effects in dioxovanadium(V) schiff-base complexes: Tuning the outcomes of oxidation reactions
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Dioxovanadium(V) salicylaldehyde semicarbazone complexes with substituents on the ligand that span the range of electron donating (methoxy) to electron withdrawing (nitro) have been synthesized and characterized by NMR, IR, CV and EPR. The reactivity of these complexes toward the oxidation of styrene (as compared to the proteo complex and vanadyl acetylacetonate) has been studied in the presence of two different oxidants (hydrogen peroxide and tert-butyl hydrogen peroxide, TBHP). The complexes have been shown to exhibit different selectivity towards epoxidation versus oxidative cleavage based on the substitution of the ligand and the oxidant chosen. Epoxidation is favored with the methoxy substituted complex in the presence of hydrogen peroxide, while oxidative cleavage is the preferred reaction pathway for the nitro substituted complex with hydrogen peroxide. Conversions for these reaction are comparable to similar catalysts but with improved selectivity.
- McCaffrey, Vanessa P.,Conover, Olivia Q.,Bernard, Michael A.,Yarranton, Jonathan T.,Lessnau, Nicholas R.,Hempfling, Jordan P.
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- Lipase catalysed oxidations in a sugar-derived natural deep eutectic solvent
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Chemoenzymatic oxidations involving the CAL-B/H2O2 system was developed in a sugar derived Natural Deep Eutectic Solvent (NaDES) composed by a mixture of glucose, fructose and sucrose. Good to excellent conversions of substrates like cyclooctene, limonene, oleic acid and stilbene to their corresponding epoxides, cyclohexanone to its corresponding lactone and 2-phenylacetophenone to its corresponding ester, demonstrate the viability of the sugar NaDES as a reaction medium for epoxidation and Baeyer-Villiger oxidation.
- Vagnoni, Martina,Samorì, Chiara,Pirini, Daniele,Vasquez De Paz, Maria Katrina,Gidey, Dawit Gebremichael,Galletti, Paola
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- Bifunctional Metal-Organic Layers for Tandem Catalytic Transformations Using Molecular Oxygen and Carbon Dioxide
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Tandem catalytic reactions improve atom- and step-economy over traditional synthesis but are limited by the incompatibility of the required catalysts. Herein, we report the design of bifunctional metal-organic layers (MOLs), HfOTf-Fe and HfOTf-Mn, consisting of triflate (OTf)-capped Hf6 secondary building units (SBUs) as strong Lewis acidic centers and metalated TPY ligands as metal active sites for tandem catalytic transformations using O2 and CO2 as coreactants. HfOTf-Fe effectively transforms hydrocarbons into cyanohydrins via tandem oxidation with O2 and silylcyanation whereas HfOTf-Mn converts styrenes into styrene carbonates via tandem epoxidation and CO2 insertion. Density functional theory calculations revealed the involvement of a high-spin FeIV (S = 2) center in the challenging oxidation of the sp3 C-H bond. This work highlights the potential of MOLs as a tunable platform to incorporate multiple catalysts for tandem transformations.
- Jiang, Xiaomin,Lan, Guangxu,Lin, Wenbin,Ni, Kaiyuan,Quan, Yangjian,Shi, Wenjie,Song, Yang,Wang, Cheng
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supporting information
p. 16718 - 16724
(2021/10/21)
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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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- Immobilization of molybdenum-based complexes on dendrimer-functionalized graphene oxide and their catalytic activity for the epoxidation of alkenes
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Two novel molybdenum-based heterogeneous catalysts immobilized on dendrimer-functionalized graphene oxide via electrostatic interactions (Mo-1) or covalent bonding (Mo-2) are reported. The catalysts show excellent catalysis in epoxidation of alkenes with high conversion, better selectivity and good recyclability. The characteristics were identified by SEM, TEM (EDS-mapping), FT-IR, XRD, and XPS. The cause of the difference between the two catalysts is supported by DFT calculations.
- Cheng, Maosheng,Fan, Zhanfang,Lin, Bin,Liu, Yang,Liu, Yongqing
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- Domino Processes of Arynes Reacting with Three Classes of Nucleophiles for Organic Syntheses
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Synthetic application of arynes is broadened by their reactions with neutral N-, S-, and O-containing nucleophiles to produce three types of compounds. Accordingly, 1,2-dihydroquinolines are synthesized from Schiff bases, alkynes, and arynes through a Diels-Alder reaction. Epoxides are prepared from thioethers and arynes along with aldehydes or ketones through a Johnson-Corey-Chaykovsky reaction. Phenolic ethers are produced from allyl ethers and arynes through a Claisen-type rearrangement. These target molecules, including natural products γ-asarone, asaricin, and a cholesteryl phenolic ether, are formed through reactions initiated by arynes. These new reactions share a prevailing feature of domino processes, which are carried out in a single flask and afford the desired products in good to high yields.
- Hwu, Jih Ru,Panja, Avijit,Gupta, Nitesh K.,Hu, Yu-Chen,Tan, Kui-Thong,Lin, Chun-Cheng,Hwang, Kuo-Chu,Hsu, Ming-Hua,Huang, Wen-Chieh,Tsay, Shwu-Chen
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p. 683 - 693
(2021/01/18)
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- A stand-alone cobalt bis(dicarbollide) photoredox catalyst epoxidates alkenes in water at extremely low catalyst load
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The cobalt bis(dicarbollide) complex, Na[3,3′-Co(η5-1,2-C2B9H11) (Na[1]), is an effective photoredox catalyst for the oxidation of alkenes to epoxides in water. Advantageous features of Na[1] include its lack of photoluminescence, high solubility and surfactant behavior in aqueous media, as well as the donor ability of the carborane ligand and high oxidizing power of the Co4+/3+ couple. These features differentiate it from the well-known and widely used photosensitizer tris (2,2′-bipyridine) ruthenium(ii) ([Ru(bpy)3]2+), which also participates in electron transfer through an outer sphere mechanism. A comparison of the catalytic performance of [Ru(bpy)3]2+ with Na[1] for alkene photo-oxidation is fully in favor of Na[1], as the former shows very low or null efficiency. With a catalyst loading of 0.1 mol% conversions between 65-97% have been obtained in short reaction times, 15 minutes, with moderate selectivity for the corresponding epoxide, due to the formation of side products as diols. But when the catalyst loading is reduced to 0.01 mol%, the selectivity for the corresponding epoxide increased considerably, being the only compound formed after 15 minutes of reaction (selectivity >99%). High TON values have been obtained (TON = 8500) for the epoxidation of aromatic and aliphatic alkenes in water. We have verified that Na[3,3′-Co(η5-1,2-C2B9H11)2] acts as a photocatalyst in both the epoxidation of alkenes and in their hydroxylation in aqueous medium with a higher rate for epoxidation than for hydroxylation. Preliminary photooxidation tests using methyl oleate as the substrate led to the selective epoxidation of the double bond. These results represent a promising starting point for the development of practical methods for the processing of unsaturated fatty acids, such as the valorisation of animal fat waste using this sustainable photoredox catalyst. This journal is
- Guerrero, Isabel,Romero, Isabel,Teixidor, Francesc,Vi?as, Clara
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supporting information
p. 10123 - 10131
(2021/12/27)
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- Microwave-Assisted Palladium-Catalyzed Reductive Cyclization/Ring-Opening/Aromatization Cascade of Oxazolidines to Isoquinolines
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An efficient palladium-catalyzed reaction of N-propargyl oxazolidines for the construction of 4-substituted isoquinolines under microwave irradiation is developed. This transformation proceeds through a sequential palladium-catalyzed reductive cyclization/ring-opening/aromatization cascade via C-O and C-N bond cleavages of the oxazolidine ring. The practical value of this method has also been explored by conducting a millimole-scale reaction, as well as by transforming the isoquinoline into a key intermediate for the synthesis of a lamellarin analogue.
- Xu, Xianjun,Feng, Huangdi,Van Der Eycken, Erik V.
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supporting information
p. 6578 - 6582
(2021/09/02)
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- Cu(ii)Cl2containing bispyridine-based porous organic polymer support preparedviaalkyne-azide cycloaddition as a heterogeneous catalyst for oxidation of various olefins
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A new type of porous organic polymer (POP) based heterogeneous catalystCu-POPwas prepared by immobilizing Cu(ii)Cl2into bpy containing POP preparedviaalkyne-azide cycloaddition. This new catalyst showed efficient catalytic activities and outstanding reusability. Remarkably, one batch ofCu-POPwas continuously used for all olefins without losing its activity by simply washing.
- Choi, Hye Min,Lee, Suk Joong,Yoon, Jongho
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supporting information
p. 9149 - 9152
(2020/06/17)
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- Biochar as supporting material for heterogeneous Mn(II) catalysts: Efficient olefins epoxidation with H2O2
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A novel type of hybrid catalytic materials [MnII-L?BC] has been developed using biochar (BC) as support material for covalent grafting of a MnII Schiff-base catalyst (MnII-L). The hybrid [MnII-L?BC] materials have been evaluated for an important catalytic process, epoxidation of olefins using H2O2 as oxidant. A number of different substrates were used, with cyclohexene achieving the highest yields. When compared to the non-grafted, homogeneous MnII-L, the hybrid catalysts [MnII-L?BC] show a significant enhancement of the catalytic efficiency i.e. as documented by the increase of Turnover Numbers (TONs) (826 for [MnII-L-SS550ox] and 822 for [MnII-L-SW550ox]) and Turnover Frequencies (TOFs) (551 h?1 for [MnII-L-SS550ox] and 411 h?1 for [MnII-L-SW550ox]). The interfacial catalytic mechanism and the role of the BC support have been analyzed by Raman and Electron Paramagnetic Resonance spectroscopies. Based on these data we discuss a mechanism where the high efficiency of the hybrid materials involves the biochar carbon layers acting as promoters of the substrate and products kinetics. To a broader context, this work exemplifies that biochar-based hybrid materials are potent for oxidative catalysis technologies.
- Borges Regitano, Jussara,Deligiannakis, Yiannis,Gemenetzi, Aikaterini,Louloudi, Maria,Mavrogiorgou, Alexandra,Pierri, Leticia
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- Immobilization of (tartrate-salen)Mn(III) polymer complexes into SBA-15 for catalytic asymmetric epoxidation of alkenes
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A series of (tartrate-salen)Mn(III) polymer complexes were prepared and immobilized into SBA-15, being subsequently employed as catalysts in the asymmetric epoxidation of alkenes. 1H NMR, FT-IR, UV–vis, elemental analysis, GPC and ICP-AES demonstrated the successful synthesis of polymer complexes, while powdered XRD, nitrogen physisorption and XPS studies proved the immobilization of polymer complexes into SBA-15. Both homogeneous and heterogeneous catalysis revealed that configurations of major epoxide products were still determined by salen chirality but e.e. values could be improved when tartrate and salen were configurationally identical. Combinations of (R,R)-salen with (R,R)-tartrate usually offered higher enantioselectivities. SBA-15 was satisfactory supporting material due to the high enantioselectivities and recycling yields obtained. The synthesized SBA-15-supported (tartrate-salen)Mn(III) catalysts showed continuous high enantioselectivities for epoxidation of α-methylstyrene, indicating great prospects for large-scale production.
- Jia, Yihong,ALOthman, Zeid A.,Liang, Rui,Cha, Shuangshuang,Li, Xiaoyong,Ouyang, Weiyi,Zheng, Aqun,Osman, Sameh M.,Luque, Rafael,Sun, Yang
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- New chiral stationary phases for liquid chromatography based on small molecules: Development, enantioresolution evaluation and chiral recognition mechanisms
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Recently, we reported the development of new chiral stationary phases (CSPs) for liquid chromatography (LC) based on chiral derivatives of xanthones (CDXs). Based on the most promising CDX selectors, 12 new CSPs were successfully prepared starting from suitable functionalized small molecules including xanthone and benzophenone derivatives. The chiral selectors comprising one, two, three, or four chiral moieties were covalently bonded to a chromatographic support and further packed into LC stainless-steel columns (150?×?2.1?mm I.D.). The enantioselective performance of the new CSPs was evaluated by LC using different classes of chiral compounds. Specificity for enantioseparation of some CDXs was observed in the evaluation of the new CSPs. Besides, assessment of chiral recognition mechanisms was performed by computational studies using molecular docking approach, which are in accordance with the chromatographic parameters. X-Ray analysis was used to establish a chiral selector 3D structure.
- Phyo, Ye' Zaw,Teixeira, Joana,Tiritan, Maria Elizabeth,Cravo, Sara,Palmeira, Andreia,Gales, Luís,Silva, Artur M.S.,Pinto, Madalena M.M.,Kijjoa, Anake,Fernandes, Carla
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- Chirally-Modified Graphite Oxide as Chirality Inducing Support for Asymmetric Epoxidation of Olefins with Grafted Manganese Porphyrin
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Abstract: A chirality inducer was prepared by graphite oxide (GO) functionalization with enantiopure l-tartrate (GO*) and used as asymmetric support for a covalently-linked manganese porphyrine complex [Mn(TPyP)OAc]. The thereby obtained heterogeneous catalyst, GO*-[Mn(TPyP)OAc], showed excellent performance and ee-values of 92–99% for the asymmetric epoxidation of prochiral olefins with O2 as oxidant and isobutyraldehyde as co-reductant in acetonitrile; linear terminal olefins with 54–76% conversion and quantitative conversion of aromatic olefins. The GO*-[Mn(TPyP)OAc] catalyst is highly active, recyclable, and at the same time simple and inexpensive to prepare with a chiral inducer from the chiral pool. The structure of the catalyst was elucidated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET analysis,?FT-IR, Raman, and photoluminescence spectroscopic methods. Graphic Abstract: Graphite oxide functionalized with an enantiopure group was used as a chirality inducer and asymmetric support for a Mn-porphyrine complex. The thereby obtained heterogeneous catalyst is an excellent enantioselective catalyst for the epoxidation of prochiral olefins.[Figure not available: see fulltext.].
- Ahadi, Elahe,Hosseini-Monfared, Hassan,Schlüsener, Carsten,Janiak, Christoph,Farokhi, Afsaneh
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p. 861 - 873
(2019/11/03)
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- Manganese(Ⅲ)-iodosylbenzene complex, preparation method thereof and oxidant comprising the same
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The present invention relates to a manganese(III)-iodosylbenzene complex, a preparation method thereof, and an oxidant comprising the same. The manganese(III)-iodosylbenzene complex provided in one aspect of the present invention has an effect of inducing a hydrogen atom abstraction (HAA) reaction of cyclohexadiene, dihydroanthracene and xanthine, and an oxygen atom transfer (OAT) reaction of thioanisole and stilbene with excellent electrophilic reactivity. The manganese(III)-iodosylbenzene complex is represented by a compound of formula 1: [Mn^III(L)(OIPh)(OH)]^2+.COPYRIGHT KIPO 2020
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Paragraph 0130; 0143-0147; 0153-0166
(2020/09/22)
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- Visible-light assisted of nano Ni/g-C3N4 with efficient photocatalytic activity and stability for selective aerobic C?H activation and epoxidation
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A selective, economical, and ecological protocol has been described for the oxidation of methyl arenes and their analogs to the corresponding carbonyl compounds and epoxidation reactions of alkenes with molecular oxygen (O2) or air as a green oxygen source, under mild reaction conditions. The nano Ni/g-C3N4 exhibited high photocatalytic activity, stability, and selectivity in the C?H activation of methyl arenes, methylene arenes, and epoxidation of various alkenes under visible- light irradiation without the use of an oxidizing agent and under base free conditions.
- Akrami, Zahra,Hosseini-Sarvari, Mona
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supporting information
(2020/10/13)
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- Method for synthesizing epoxy compound by catalyzing epoxidation of olefin with nano-alumina
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The invention belongs to the field of organic synthesis and catalysis, and discloses a method for synthesizing an epoxy compound by catalyzing epoxidation of olefin with nano-alumina. The method comprises the following steps: adding a solvent, olefin, nano-alumina and fatty aldehyde into a reactor to obtain a mixed solution, vacuumizing a reaction container, introducing oxygen, heating and stirring for a reaction by taking olefin as a raw material, taking nano-alumina as a catalyst and taking fatty aldehyde as a reducing agent, obtaining a reaction solution after the reaction is finished, andseparating and purifying the reaction solution to obtain the epoxy compound. The method has the advantages of cheap and easily available in the catalyst, easy to obtain, mild in reaction condition, wide in substrate applicability and safe and simple to operate, and has a potential industrial application prospect.
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Paragraph 0117-0125
(2020/06/17)
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- Post-synthetic Modification of DUT-5-based Metal Organic Frameworks for the Generation of Single-site Catalysts and their Application in Selective Epoxidation Reactions
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New single-site catalysts based on mixed-linker metal-organic frameworks with DUT-5 structure, which contain immobilized Co2+, Mn2+ and Mn3+ complexes, have successfully been synthesized via post-synthetic modification. 2,
- Yildiz, Ceylan,Kutonova, Ksenia,O?wald, Simon,Titze-Alonso, Alba,Bitzer, Johannes,Br?se, Stefan,Kleist, Wolfgang
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p. 1134 - 1142
(2020/01/21)
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- Formal [3+2] cycloaddition reactions of electron-rich aryl epoxides with alkenes under Lewis acid catalysis affording tetrasubstituted tetrahydrofurans
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We report on the regio- and stereoselective synthesis of tetrahydrofurans by reaction between epoxides and alkenes in the presence of a Lewis acid. This is an unprecedented formal [3+2] cycloaddition reaction between an epoxide and an alkene. The chemical reaction represents a very concise synthesis of tetrahydrofurans from accessible starting compounds.
- Macías-Villamizar, Víctor E.,Cuca-Suárez, Luís,Rodríguez, Santiago,González, Florenci V.
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supporting information
(2020/02/18)
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- Method for catalyzing epoxidation of olefin
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The invention discloses a method for catalyzing epoxidation of olefin. According to the method, an olefin compound is used as a raw material, hydrogen peroxide, peracetic acid, tert-butyl hydroperoxide and m-chloroperoxybenzoic acid are used as oxidants, a metalloporphyrin-based super-cross-linked polymer is used as a catalyst, and a catalytic reaction is carried out at a reaction temperature of 25-80 DEG C to obtain an epoxide at high selectivity. The method has the advantages of simple process, high yield, catalyst recyclability, mild conditions and the like.
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Paragraph 0035-0036
(2020/04/17)
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- A Bifunctional Iron Nanocomposite Catalyst for Efficient Oxidation of Alkenes to Ketones and 1,2-Diketones
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We herein report the fabrication of a bifunctional iron nanocomposite catalyst, in which two catalytically active sites of Fe-Nx and Fe phosphate, as oxidation and Lewis acid sites, were simultaneously integrated into a hierarchical N,P-dual doped porous carbon. As a bifunctional catalyst, it exhibited high efficiency for direct oxidative cleavage of alkenes into ketones or their oxidation into 1,2-diketones with a broad substrate scope and high functional group tolerance using TBHP as the oxidant in water under mild reaction conditions. Furthermore, it could be easily recovered for successive recycling without appreciable loss of activity. Mechanistic studies disclose that the direct oxidation of alkenes proceeds via the formation of an epoxide as intermediate followed by either acid-catalyzed Meinwald rearrangement to give ketones with one carbon shorter or nucleophilic ring-opening to generate 1,2-diketones in a cascade manner. This study not only opens up a fancy pathway in the rational design of Fe-N-C catalysts but also offers a simple and efficient method for accessing industrially important ketones and 1,2-diketones from alkenes in a cost-effective and environmentally benign fashion.
- Ma, Zhiming,Ren, Peng,Song, Tao,Xiao, Jianliang,Yang, Yong,Yuan, Youzhu
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p. 4617 - 4629
(2020/05/19)
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- Synthesis of Epoxides from Alkyl Bromides and Alcohols with in Situ Generation of Dimethyl Sulfonium Ylide in DMSO Oxidations
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Direct conversion of the readily available alkyl bromides and alcohols to value-added epoxides using dimethyl sulfoxide (DMSO) under mild reaction conditions has been developed. Benzyl and allyl bromides, and activated and unactivated alcohols all proceeded smoothly to give epoxides in high to excellent yield. Dimethyl sulfide, generated by DMSO oxidations, was in situ elaborated to form the substituted dimethyl sulfonium ylide species that participates in the Corey-Chaykovsky epoxidation in a domino and one-pot fashion, respectively.
- Zhang, Zhi-Wei,Li, Hai-Bo,Li, Jin,Wang, Cui-Cui,Feng, Juan,Yang, Yi-Hua,Liu, Shouxin
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p. 537 - 547
(2020/01/02)
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- An Aminopyridinium Ionic Liquid: A Simple and Effective Bifunctional Organocatalyst for Carbonate Synthesis from Carbon Dioxide and Epoxides
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An aminopyridinium ionic liquid is presented as a green, tunable, and active metal-free one-component catalytic system for the atom-efficient transformation of oxiranes and CO2 to cyclic carbonates. Inclusion of a positively charged moiety into aminopyridines, through a simple single-step synthesis, provides a one-component ionic liquid catalytic system with superior activity; effective in ring opening of epoxide, CO2 inclusion, and stabilization of oxoanionic intermediates. An efficiency assessment of a variety of positively charged aminopyridines was pursued, and the impact of temperature, catalyst loading, and the kind of nucleophile on the catalytic performance was also investigated. Under solvent-free conditions, this bifunctional organocatalytic system was used for the preparation of 18 examples of cyclic carbonates from a broad range of alkyl- and aryl-substituted oxiranes and CO2, where up to 98 percent yield and high selectivity were achieved. DFT calculations validated a mechanism in which nucleophilic ring-opening and CO2 inclusion occur simultaneously towards cyclic carbonate formation.
- Al-Harrasi, Ahmed,Ebrahimi, Amirhossein,Khosravi, Hormoz,Rezazadeh, Mostafa,Rostami, Ali
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p. 1587 - 1595
(2020/08/05)
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- Dendrimer crown-ether tethered multi-wall carbon nanotubes support methyltrioxorhenium in the selective oxidation of olefins to epoxides
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Benzo-15-crown-5 ether supported on multi-wall carbon nanotubes (MWCNTs) by tethered poly(amidoamine) (PAMAM) dendrimers efficiently coordinated methyltrioxorhenium in the selective oxidation of olefins to epoxides. Environmentally friendly hydrogen peroxide was used as a primary oxidant. Up to first and second generation dendrimer aggregates were prepared by applying a divergent PAMAM methodology. FT-IR, XRD and ICP-MS analyses confirmed the effective coordination of methyltrioxorhenium by the benzo-15-crown-5 ether moiety after immobilization on MWCNTs. The novel catalysts converted olefins to the corresponding epoxides in high yield without the use of Lewis base additives, or anhydrous hydrogen peroxide, the catalyst being stable for more than six oxidative runs. In the absence of the PAMAM structure, the synthesis of diols largely prevailed.
- Bizzarri, Bruno Mattia,Botta, Lorenzo,Crucianelli, Marcello,Fanelli, Angelica,Ferella, Francesco,Gontrani, Lorenzo,Sadun, Claudia,Saladino, Raffaele
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p. 17185 - 17194
(2020/05/18)
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- An effective strategy for creating asymmetric MOFs for chirality induction: A chiral Zr-based MOF for enantioselective epoxidation
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Recently the construction of chiral MOFs (CMOFs) has been very challenging and complex. For the first time, we synthesized a chiral Zr-based MOF with l-tartaric acid by solvent-assisted ligand incorporation (SALI). We show that a CMOF can be postsynthetically generated by a simple method: incorporating chiral carboxylic groups on the achiral NU-1000. The post-synthesized chiral NU-1000 was used as an asymmetric support for producing a chiral catalyst with molybdenum catalytic active centers as Lewis acid sites. Enantioselective epoxidation of various prochiral alkens to epoxids by using [C-NU-1000-Mo] is comparable to that using other asymmetric homogeneous and heterogeneous catalysts, along with high enantiomeric excess and selectivity to epoxide (up to 100%). The CMOF could be reused in the styrene oxidation after five cycles without substantial deterioration in the CMOF crystallinity or catalytic performance.
- Berijani, Kayhaneh,Morsali, Ali,Hupp, Joseph T.
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p. 3388 - 3397
(2019/07/10)
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- Dual activity of durable chiral hydroxyl-rich MOF for asymmetric catalytic reactions
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The quest to prepare of asymmetric heterogeneous catalysts with both effective Br?nsted acid sites (BASs) and Lewis acid sites is very significant challenge. Herein, we report the construction of a chiral metal-organic framework with two kinds of catalytic active sites (Lewis acid/Br?nsted acid). It contains coordinative unsaturation metal centers and chiral functional groups that have cooperation in the catalytic activity. In the synthesized CMOF, the chiral decoration of metal node was performed through the practical method: anions exchange hypothesis (post-synthetic exchange). For this aim, the elimination of framework fluorides happened by using the enantiopure auxiliary anions (L-(+)-tartrate anion (tart?)) that led to a chiral cationic MOF with eventual chemical formula [Cr3tart(H2O)2O(bdc)3]. XRD, BET, 1H NMR, SEM and EDX were employed to characterize of the present CMIL. Despite the chiral tartrate anions generate a chiral environment, they have main role in the activating of epoxide ring due to hydrogen-bonding interaction. Experiments show that the enantiopure tartrate-functionalized MIL-101(Cr) as a green asymmetric catalyst has the considerable performance in the enantioselective reactions due to chiral modified surface without remarkable loss in activity.
- Berijani, Kayhaneh,Morsali, Ali
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- Unified Mechanism of Oxygen Atom Transfer and Hydrogen Atom Transfer Reactions with a Triflic Acid-Bound Nonheme Manganese(IV)-Oxo Complex via Outer-Sphere Electron Transfer
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Outer-sphere electron transfer from styrene, thioanisole, and toluene derivatives to a triflic acid (HOTf)-bound nonheme Mn(IV)-oxo complex, [(N4Py)MnIV(O)]2+-(HOTf)2 (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine), has been shown to be the rate-determining step of different types of redox reactions such as epoxidation, sulfoxidation, and hydroxylation of styrene, thioanisole, and toluene derivatives, respectively, by [(N4Py)MnIV(O)]2+-(HOTf)2. The rate constants of HOTf-promoted epoxidation of all styrene derivatives with [(N4Py)MnIV(O)]2+ and electron transfer from electron donors to [(N4Py)MnV(O)]2+ exhibit a remarkably unified correlation with the driving force of outer-sphere electron transfer in light of the Marcus theory of electron transfer. The same electron-transfer driving force dependence is observed in the oxygen atom transfer from [(N4Py)MnIV(O)]2+-(HOTf)2 to thioanisole derivatives as well as in the hydrogen atom transfer from toluene derivatives to [(N4Py)MnIV(O)]2+-(HOTf)2. Thus, mechanisms of oxygen atom transfer (epoxidation and sulfoxidation) reactions of styrene and thioanisole derivatives and hydrogen atom transfer (hydroxylation) reactions of toluene derivatives by [(N4Py)MnIV(O)]2+-(HOTf)2 have been unified for the first time as the same reaction pathway via outer-sphere electron transfer, followed by the fast bond-forming step, which exhibits the singly unified electron-transfer driving force dependence of the rate constants as outer-sphere electron-transfer reactions. In the case of the epoxidation of cis-stilbene by [(N4Py)MnIV(O)]2+-(HOTf)2, the isomerization of cis-stilbene radical cation to trans-stilbene radical cation occurs after outer-sphere electron transfer from cis-stilbene to [(N4Py)MnIV(O)]2+-(HOTf)2 to yield trans-stilbene oxide selectively, which is also taken as evidence for the occurrence of electron transfer in the acid-catalyzed epoxidation.
- Lee, Yong-Min,Kim, Surin,Ohkubo, Kei,Kim, Kyung-Ha,Nam, Wonwoo,Fukuzumi, Shunichi
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p. 2614 - 2622
(2019/03/04)
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- Mononuclear manganese(III) complex with a monodeprotonated N-(2-pyridylmethyl)iminodiisopropanol ligand: synthesis, crystal structure, and catalytic properties
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The reaction of N-(2-pyridylmethyl)iminodiisopropanol (H2pmidip), sodium azide, and manganese(II) salt in methanol leads to the isolation of a monomeric manganese complex of [Mn(Hpmidip)(N3)2]·CH3OH (1). The structure of 1 has been verified by single crystal X-ray diffractometry. The manganese ion in 1 is bonded with one Hpmidip? as tetradentate and two azido ligands in cis position in which the manganese ion is displayed a distorted octahedral geometry. One of two hydroxyl groups in the coordinated Hpmidip? ligand is protonated, while the other one is deprotonated. The manganese ion is assigned as 3+ oxidation state that verified by bond lengths and bond valence sum. Furthermore, the complex reveals a dimeric structure by O[sbnd]H?O hydrogen bonding interactions. 1 exhibited selective and effective catalytic properties for various olefins with moderate yields using m-CPBA (meta-chloroperoxybenzoic acid). The mechanistic studies of 1 for olefin epoxidation have been investigated by the Hammett study, the O[sbnd]O bond cleavage of PPAA (peroxyphenylacetic acid) as a mechanistic probe, and competitive experiments of cis- and trans-2-octene.
- Choi, Jihye,Lee, Sojeong,Jeong, Ah Rim,Kim, Cheal,Min, Kil Sik
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- Iterative synthesis of alkenes by insertion of lithiated epoxides into boronic esters
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The insertion of lithiated epoxides into boronic esters followed by thermal syn-elimination provides a stereospecific entry to alkenes. This process avoids transition metals and is amenable to iteration to provide higher substitution patterns.
- Bojaryn, Kevin,Fritsch, Stefan,Hirschhaüser, Christoph
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supporting information
p. 2218 - 2222
(2019/04/10)
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- A novel homochiral metal-organic framework with an expanded open cage based on (: R)-3,3′-bis(6-carboxy-2-naphthyl)-2,2′-dihydroxy-1,1′-binaphthyl: synthesis, X-ray structure and efficient HPLC enantiomer separation
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A new homochiral metal-organic framework (MOF) with an expanded open cage based on the (R)-3,3′-bis(6-carboxy-2-naphthyl)-2,2′-dihydroxy-1,1′-binaphthyl ligand was synthesized and utilized as a novel chiral stationary phase for high-performance liquid chromatography. Twelve racemates including sec-alcohols, sulfoxides, epoxides, lactone, 1,3-dioxolan-2-one, and oxazolidinone were used as analytes for evaluating the separation properties of the chiral-MOF-packed column. Experimentally, the homochiral MOF offered good molecular recognition ability, which suggests good prospects for the application of chiral MOFs as stationary phases for enantioseparation.
- Tanaka, Koichi,Kawakita, Tomohiro,Morawiak, Maja,Urbanczyk-Lipkowska, Zofia
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p. 487 - 493
(2019/01/21)
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- HPLC with cellulose Tris (3,5-DimethylPhenylcarbamate) chiral stationary phase: Influence of coating times and coating amount on chiral discrimination
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Coating cellulose tris (3,5-dimethylphenylcarbamate) (CDMPC) on silica gels with large pores have been demonstrated as an efficient way for the preparation of chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC). During the process, a number of parameters, including the type of coating solvent, amount of coating, and the method for subsequent solvent removing, have been proved to affect the performance of the resultant CSPs. Coating times and the concentration of coating solution, however, also makes a difference to CSPs' performance by changing the arrangement of cellulose derivatives while remaining the coating amount constant, have much less been studied before, and thereby, were systematically investigated in this work. Results showed that CSPs with more coating times exhibited higher chiral recognition and column efficiency, suggesting that resolution was determined by column efficiency herein. Afterwards, we also investigated the effect of coating amount on the performance of CSPs, and it was shown that the ability of enantio-recognition did not increase all the time as the coating amount; and four of seven racemates achieved best resolution when the coating amount reached to 18.37%. At the end, the reproducibility of CDMPC-coated CSPs were further confirmed by two methods, ie, reprepared the CSP-0.15-3 and reevaluated the effect of coating times.
- Wei, Qiuhong,Su, Hongjiu,Gao, Diannan,Wang, Shudong
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p. 164 - 173
(2019/01/18)
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- Highly selective and efficient olefin epoxidation with pure inorganic-ligand supported iron catalysts
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Over the past two decades, there have been major developments in the transition iron-catalyzed selective oxidation of alkenes to epoxides; a common structure found in drug, isolated natural products, and fine chemicals. Many of these approaches have enabled highly efficient and selective epoxidation of alkenes via the design of specialized ligands, which facilitates to control the activity and selectivity of the reactions catalyzed by iron atom. Herein, we report the development of the olefin epoxidation with inorganic-ligand supported iron-catalysts using 30% H2O2 as an oxidant, and the mechanism is similar to iron-porphyrin type. With the catalyst 1, (NH4)3[FeMo6O18(OH)6], various aromatic and aliphatic alkenes were successfully transformed into the corresponding epoxides with excellent yields as well as chemo- and stereo-selectivity. This catalytic system possesses the advantages of being able to avoid the use of expensive, toxic, air/moisture sensitive and commercially unavailable organic ligands. The generality of this methodology is simple to operate and exhibits high catalytic activity as well as excellent stability, which gives it the potential to be used on an industrial scale, and maybe opens a way for the catalytic oxidation reaction via inorganic-ligand coordinated iron catalysis.
- Zhou, Zhuohong,Dai, Guoyong,Ru, Shi,Yu, Han,Wei, Yongge
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supporting information
p. 14201 - 14205
(2019/10/02)
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- Conglomerated system of Ag nanoparticles decorated Al2O3 supported cobalt and copper complexes with enhanced catalytic activity for oxidation reactions
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In this study, our aim is to increase the effectiveness of heterogeneous catalysts by reducing its drawback. For this purpose we have developed a new method to synthesize heterogeneous catalyst by dispersion of Silver nanoparticles onto Alumina supported cobalt and copper Schiff base complexes (AgNPs-Al2O3@ML).Initially Schiff base and its corresponding Co (III) complex, (CoL) and Cu (II) complex, (CuL)(L = Schiff base) were synthesized. Both the complexes were immobilized on Al2O3 to generate Al2O3@CoL (HT1) and Al2O3@CuL (HT2). Finally, Silver was dispersed onto both the heterogeneous complexes to generate our desired heterogeneous catalyst Ag NPs-Al2O3@CoL (AgHT1) and Ag NPs-Al2O3@CuL (AgHT2).A hike in BET surface area from HT1 to AgHT1 highlighted the fruitfulness of decoration of Ag NPs onto HT1. FESEM studies of AgHT1 and AgHT2 reveal the formation of pyramidal type silver nanoparticle onto HT1 and HT2. The catalytic ability of CoL, CuL (homogeneous catalyst), HT1, HT2 and AgHT1, AgHT2 (heterogeneous catalyst) were investigated by enrolling it on oxidation of alcohols, alkanes and epoxidation of alkenes using H2O2 as oxidant. Among the four heterogeneous catalysts AgHT1 showed highest activity. Finally a plausible mechanism has been put forward to elucidate the role of each substituent of the catalytic system. The heterogeneous catalysts HT1, HT2, AgHT1 and AgHT2 can be reused up to six times without any significant loss in its catalytic activity.
- Chakraborty, Tonmoy,Chakraborty, Aratrika,Maity, Suvendu,Das, Debasis,Chattopadhyay, Tanmay
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p. 104 - 113
(2018/11/21)
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- Chiral salen Cr(iii) complexes encapsulated in thermo-responsive polymer nanoreactors for asymmetric epoxidation of alkenes in water
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Chiral salen Cr(iii) (Cr(salen)) complexes were encapsulated in thermo-responsive polymer nanoreactors through folding an amphiphilic random copolymer of poly(N-isopropylacrylamide-co-IL/Cr(salen)) (poly(NIPAAM-co-IL/Cr(salen)) around Cr(salen) in water. The resulting catalytic nanoreactors exhibited several advantages over the traditional Cr(salen) system for asymmetric epoxidation of alkenes in water. First, they were dispersed in water, behaving as a quasi-homogeneous catalyst for the aqueous asymmetric epoxidation. Second, they effectively sequestered substrates from the surrounding environment, creating a highly concentrated environment for efficient catalysis. Third, water was excluded from the nanoreactor, minimizing the undesired hydrolysis of epoxides. As a result, the compartmentalized catalysts mediated aqueous asymmetric epoxidation with unprecedented yields (92-95%) and enantioselectivities (ee, 92-99%), whereas the traditional Cr(salen) catalyst was far less efficient (4-12% yield and 29-44% ee). Moreover, the catalytic nanoreactor could be facilely recovered for reuse by thermo-controlled separation. This work highlighted the potential of using folded polymers as a platform for developing highly efficient catalytic nanoreactors for a number of important organic transformations in water.
- Wang, Weiying,Li, Chaoping,Pi, Yibing,Wang, Jiajun,Tan, Rong,Yin, Donghong
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p. 5626 - 5635
(2019/10/23)
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- Designing of a magnetically separable Fe3O4@dopa@ML nano-catalyst for multiple organic transformations (epoxidation, reduction, and coupling) in aqueous medium
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A copper(II) macrocyclic Schiff base complex (ML) was synthesized by condensation between 2,2-dimethylpropane-1,3-diammine and 2,6-diformyl-4-butylphenol with the aim to modify the surface of widely used magnetically separable nanocatalyst Fe3O
- Dasgupta, Sanchari,Chatterjee, Sourav,Chattopadhyay, Tanmay
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p. 550 - 568
(2019/02/26)
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- Tailoring chemoenzymatic oxidation: Via in situ peracids
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Epoxidation chemistry often suffers from the challenging handling of peracids and thus requires in situ preparation. Here, we describe a two-phase enzymatic system that allows the effective generation of peracids and directly translate their activity to the epoxidation of olefins. We demonstrate the approach by application to lipid and olefin epoxidation as well as sulfide oxidation. These methods offer useful applications to synthetic modifications and scalable green processes.
- Re, Rebecca N.,Proessdorf, Johanna C.,La Clair, James J.,Subileau, Maeva,Burkart, Michael D.
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supporting information
p. 9418 - 9424
(2019/11/14)
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- Trapping of a Highly Reactive Oxoiron(IV) Complex in the Catalytic Epoxidation of Olefins by Hydrogen Peroxide
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The generation of a nonheme oxoiron(IV) intermediate, [(cyclam)FeIV(O)(CH3CN)]2+ (2; cyclam=1,4,8,11-tetraazacyclotetradecane), is reported in the reactions of [(cyclam)FeII]2+ with aqueous hydrogen peroxide (H2O2) or a soluble iodosylbenzene (sPhIO) as a rare example of an oxoiron(IV) species that shows a preference for epoxidation over allylic oxidation in the oxidation of cyclohexene. Complex 2 is kinetically and catalytically competent to perform the epoxidation of olefins with high stereo- and regioselectivity. More importantly, 2 is likely to be the reactive intermediate involved in the catalytic epoxidation of olefins by [(cyclam)FeII]2+ and H2O2. In spite of the predominance of the oxoiron(IV) cores in biology, the present study is a rare example of high-yield isolation and spectroscopic characterization of a catalytically relevant oxoiron(IV) intermediate in chemical oxidation reactions.
- Engelmann, Xenia,Malik, Deesha D.,Corona, Teresa,Warm, Katrin,Farquhar, Erik R.,Swart, Marcel,Nam, Wonwoo,Ray, Kallol
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supporting information
p. 4012 - 4016
(2019/02/20)
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- Olefins oxidation with molecular O2 in the presence of chiral Mn (III) salen complex supported on magnetic CoFe2O4@SiO2@CPTMS
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In the present study, CoFe2O4@SiO2@CPTMS nanocomposite was synthesized and the homogeneous chiral Mn-salen complex was anchored covalently onto the surface of CoFe2O4@SiO2@CPTMS nanocomposite. The heterogeneous Mn-salen magnetic nanocatalyst (CoFe2O4@SiO2@CPTMS@ chiral Mn (III) Complex) was characterized by different techniques including transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Then, the aerobic enantioselective oxidation of olefins to the corresponding epoxide was investigated in the presence of magnetic chiral CoFe2O4@SiO2@Mn (III) complex at ambient conditions within 90?min. The results showed the corresponding products were synthesized with excellent yields and selectivity. In addition, the heterogeneous CoFe2O4@SiO2@ CPTMS@ chiral Mn (III) complex has benefits such as high selectivity and comparable catalytic reactivity with its homogeneous analog as well as mild reaction condition, facile recovery, and recycling of the heterogeneous catalyst.
- Hemmat, Kaveh,Nasseri, Mohammad A.,Allahresani, Ali
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- Iron(II) tetrafluoroborate complexes of new tetradentate C-scorpionates as catalysts for the oxidative cleavage of: Trans-stilbene with H2O2
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Attachment of a 2-methylpyridyl group onto the unique 1-nitrogen atom on nitrogen-confused C-scorpionates with either pyrazol-1-yl or 3,5 dimethylpyrazol-1-yl donors gives two new cis-directing tetradentate-N4 ligands (L and L?). The complexes [(L or L?)Fe(CH3CN)2](BF4)2 (1 or 2) were prepared, fully characterized, and investigated for their ability to catalyse the oxidative cleaveage of trans-stilbene in CH3CN. Complexes 1 and 2 are capable of catalysing stilbene cleavage when H2O2 is used as an oxidant but up to six different products are formed, with CC cleavage products (benzaldehyde and benzoic acid) dominating over four products of oxygen transfer. Catalytic amounts of 1 or 2 enhance the ability for the organic photocatalyst riboflavin tetraacetate to use atmospheric oxygen and blue light irradation (450-460 nm) to selectively cleave stilbene to benzaldehyde. However, when benzaldehyde oxidizes further to benzoic acid, the iron species begin giving increasing amounts of stilbene oxygenation products.
- Wang, Denan,Gardinier, James R.,Lindeman, Sergey V.
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p. 14478 - 14489
(2019/10/11)
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- Method for preparing epoxide by one-pot olefin aerobic epoxidation
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The invention relates to a method for preparing an epoxide by one-pot olefin aerobic epoxidation, and belongs to the technical field of organic synthesis. An olefin, an alkyl aromatic compound and analkali are added into a solvent, or an olefin, an alkyl aromatic compound and an alkali are directly mixed; the temperature is raised to 70-160 DEG C in an air or oxygen atmosphere; reacting is carried out for 1-48 hours; and the olefin is directly oxidized into the corresponding epoxide in the presence of the alkyl aromatic compound, the alkali and air (or oxygen), wherein the yield is up to 99%.In the reaction process, the generated alkyl peroxide is generated in situ and consumed in situ, so that the concentration of the alkyl peroxide is kept at a lower level; and generated alkyl peroxy free radicals can also react with the olefin to further generate the peroxide, and efficiency is improved. The method has the advantages of simple operation, mild conditions, low raw material cost andno need of special complex equipment, and has a good industrial application prospect.
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Paragraph 0074-0075
(2020/01/03)
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- A practical innovative method for highly selective oxidation of alkenes and alkanes using Fe (III) and Mn (III) porphyrins supported onto multi-wall carbon nanotubes as reusable heterogeneous catalysts
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Functionalized multi-walled carbon nanotubes were used for covalent immobilization of meso-tetrakis(4-carboxyphenyl) porphyrinatoiron (III) chloride [Fe (TCPP)Cl] and meso-tetrakis(4-carboxyphenyl) porphyrinatomanganese (III) acetate [Mn (TCPP)OAc]. The full characterization of the hybrid porphyrinic nanomaterials, by Fourier transform-infrared and UV–Vis spectroscopy, transmission electron microscopy, thermogravimetry and flame atomic absorption spectrometry is described. The oxidation of alkenes and alkanes with molecular oxygen as green oxidant in the presence of Mn- and Fe-catalysts has been studied in a comparative manner. The Fe-catalyst was shown to have higher catalytic activity compared with the Mn-catalyst. In addition, both separable solid catalysts can be recovered and reused at least 10 times along with good yields.
- Rayati, Saeed,Nafarieh, Parinaz
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