- A graphene oxide immobilized Cu(ii) complex of 1,2-bis(4-aminophenylthio)ethane: An efficient catalyst for epoxidation of olefins with tert-butyl hydroperoxide
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In this work, a new, recoverable and heterogeneous catalyst was prepared by covalent attachment of the Cu(ii) complex of 1,2-bis(4-aminophenylthio)ethane onto graphene oxide via the amide linkages. The structural and chemical nature of the catalyst was characterized by a variety of techniques such as Fourier transform infrared and diffuse reflectance UV-visible spectroscopies, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, field emission scanning electron microscopy and inductively coupled plasma atomic emission spectroscopy. The catalytic activity of this catalyst was investigated in the epoxidation of olefins with tert-butyl hydroperoxide. The catalyst has great reusability and stability in the epoxidation reactions.
- Zarnegaryan, Ali,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammdpoor-Baltork, Iraj
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- Copper(II) Schiff base complex immobilized on graphene nanosheets: a heterogeneous catalyst for epoxidation of olefins
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The present paper describes the preparation and characterization of Cu(II) Schiff base complex immobilized onto graphene oxide. The structural and morphological characterization of the heterogeneous catalyst was carried out by different techniques such as Fourier transform infrared and diffuse reflectance UV–Vis spectroscopies, X-ray diffraction, thermogravimetric analysis, nitrogen adsorption–desorption, transmission electron microscopy, field emission scanning electron microscopy and inductively coupled plasma atomic emission spectroscopy. The catalytic activity of the heterogeneous catalyst was studied in the epoxidation of various alkenes using tert-butyl hydroperoxide as an oxidant and it showed high selectivity and catalytic reactivity. The graphene-bound copper Schiff base was successfully reused for several runs without significant loss in its catalytic activity.
- Zarnegaryan, Ali,Pahlevanneshan, Zari,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammdpoor-Baltork, Iraj
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- Manganese meso-tetra-4-carboxyphenylporphyrin immobilized on MCM-41 as catalyst for oxidation of olefins with different oxygen donors in stoichiometric conditions
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Oxidation of olefins with tert-butyl hydroperoxide (TBHP), tetra-n-butylammonium periodate (TBAP) and potassium peroxomonosulfate (Oxone) in the presence of MCM-41 immobilized meso-tetra-4- carboxyphenylporphyrinatomanganese(III) acetate has been studied.
- Rayati, Saeed,Zakavi, Saeed,Jafarzadeh, Parisa,Sadeghi, Omid,Amini, Mostafa M.
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- Molybdenum Schiff base-polyoxometalate hybrid compound: A heterogeneous catalyst for alkene epoxidation with tert-BuOOH
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The hybrid compound consisting of molybdenum(salen) [salen = N,N′-bis(salicylidene)ethylnediamine] complex covalently linked to a lacunary Keggin-type polyoxometalate, K8[SiW11O39] (POM), was synthesized and characterized by elemental analysis, FT-IR, 1H NMR and diffuse reflectance UV-Vis spectroscopic methods and BET analysis. The complex, [Mo(O)2(salen)-POM], was studied, for the first time, in the epoxidation of various alkenes with tert-BuOOH and in 1,2-dichloroethane as solvent. This catalyst can catalyze epoxidation of various olefins including non-activated terminal olefins. The effect of the other parameters such as solvent, oxidant and temperature on the epoxidation of cyclooctene was also investigated. The interesting characteristic of this catalyst is that, in addition to being a heterogeneous catalyst, it gives higher yields towards epoxidation of olefins in comparison to the corresponding homogeneous [Mo(O)2(salen)] complex.
- Moghadam, Majid,Mirkhani, Valiollah,Tangestaninejad, Shahram,Mohammadpoor-Baltork, Iraj,Javadi, Maedeh Moshref
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- Efficient and selective hydrocarbon oxidation with sodium periodate catalyzed by supported manganese(III) porphyrin
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Manganese(III) tetrakis(p-sulfonatophenyl)porphyrin was successfully bound to silica modified with zirconium. The heterogeneous catalyst, MnTPPS-silica, was characterized by SEM, FT-IR and diffuse reflectance UV-Vis spectroscopic techniques. MnTPPS-silica catalyzes alkene epoxidation and alkanes hydroxylation with sodium periodate under agitation with magnetic stirring and ultrasonic irradiation in the presence of imidazole as an axial ligand. This catalytic system shows a good activity in the epoxidation of linear alkenes. Alkyl aromatic and cycloalkanes were efficiently oxidized to their corresponding alcohols and ketones in the presence of this catalyst. This new heterogeneous catalyst is of high stability and reusability in the oxidation reactions and can be reused several times without loss of its activity.
- Tangestaninejad,Moghadam,Mirkhani,Mohammadpoor-Baltork,Hoseini
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- Cleavage of the Carbon-Carbon Double Bond over Zeolites using Hydrogen eroxide
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Zeolite molecular sieves catalyse the cleavage of carbon-carbon double bonds of various alkenes in the presence of aqueous hydrogen peroxide as an oxidant; titanium silicate molecular sieves, TS-1 and TS-2 exhibit very high activity in the conversion of α-methylstyrene into acetophenone.
- Reddy, J. Sudhakar,Khire, Uday R.,Ratnasamy, P.,Mitra, Rajat B.
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- Dialkyl peroxides decomposition in the presence of quaternary ammonium halides
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Decomposition of dicumyl peroxide and cumyl tert-butyl peroxide was studied in the presence of tetraethylammonium halides in acetonitrile, dimethylformamide, 2-propanol, and acetic acid. The tetraethylammonium halides accelerate the decomposition of dialkyl peroxides in 2-propanol and acetic acid, but do not affect the reaction velocity in dimethylformamide and acetonitrile. The decomposition products character depends on the solvent nature.
- Maksyuta,Suprun,Opeida,Turovskii
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- Multi-wall carbon nanotube supported tungsten hexacarbonyl: An efficient and reusable catalyst for epoxidation of alkenes with hydrogen peroxide
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Highly efficient epoxidation of alkenes with H2O2 catalyzed by tungsten hexacarbonyl supported on multi-wall carbon nanotubes (MWCNTs) modified with 1,2-diaminobenzene is reported. The prepared catalyst, [W(CO)6@DAB-MWCNT], was characterized by elemental analysis, scanning electron microscopy, FT-IR, and diffuse reflectance UV-Vis spectroscopic methods. The prepared catalyst was applied as an efficient catalyst for green epoxidation of alkenes with hydrogen peroxide in CH3CN. This heterogeneous metal carbonyl catalyst showed high stability and reusability in epoxidation without loss of its catalytic activity. Copyright
- Nooraeipour, Mehdi,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Iravani, Nasir
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- Enhancement of the photoinduced oxidation activity of a ruthenium(II) complex anchored on silica-coated silver nanoparticles by localized surface plasmon resonance
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Plasmonic photocatalyst: Anchoring the dye [Ru(bpy)3] 2+ (bpy=2,2-bipyridine) on the surface of Ag nanoparticles coated with a thin SiO2 layer (see picture) afforded a photocatalyst whose phosphorescence emission and photoinduced oxidation activity in the selective liquid-phase oxidation of styrene are efficiently enhanced through interaction with the localized surface plasmon resonance of the core Ag nanoparticles.
- Mori, Kohsuke,Kawashima, Masayoshi,Che, Michel,Yamashita, Hiromi
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- New molybdenum(VI) complexes with thiazole-hydrazone ligand: Preparation, structural characterization, and catalytic applications in olefin epoxidation
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The reaction of [MoO2(acac)2] with (E)-2-((2-(benzo[d]thiazol-2-yl)hydrazono)methyl)-6-methoxyphenol (H2L), in acetonitrile and ethanol resulted in the formation of {[MoO2(HL)(H2O)]2[Mo6O19]·2MeCN} (1) (mononuclear cationic complex with hexamolybdate anion) and [MoO2L(EtOH)] (2) (neutral mononuclear complex), depending on the reaction conditions. In these compounds, the ligand is coordinated to the cis-MO22+ core via phenolic-oxygen, thiazole and azomethine nitrogen atoms, while the remaining sixth coordination site is occupied by the oxygen atom from the solvent molecule. Crystal and molecular structures of the compounds 1 and 2 were determined by the single crystal X-ray diffraction method. All of the investigated compounds were further characterized by elemental analysis, FT-IR and NMR spectroscopy. The molybdenum(VI) species were used as catalyst for olefin oxidation in the presence of tert-butylhydroperoxide (TBHP) as an oxidant. Under similar experimental conditions with equal Mo loading, the presence of the {[MoO2(HL)(H2O)]2[Mo6O19]·2MeCN} (1) resulted in higher oxidation conversion than [MoO2L(EtOH)] (2). It seems 1 contains two potentially active parts, the [MoO2(HL)H2O]+ cation and the Mo6O19?2 anion.
- Ghorbanloo, Massomeh,Bikas, Rahman,Ma?ecki, Grzegorz
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- Photoinduced electron transfer oxidation of α-methylstyrene with molecular oxygen sensitized by dimethoxybenzenes: A non-singlet-oxygen mechanism
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α-Methylstyrene (1) was photooxidized with oxygen in the presence of a series of alkylated dimethoxybenzenes as a sensitizer in acetonitrile, affording the cleaved ketone (2), epoxide (3) as well as a small amount of the ene product (4) in ca. 1:1:0.04 ratio. A non-singlet-oxygen mechanism is proposed, in which an excited sensitizer is quenched by oxygen to produce a sensitizer radical cation and a superoxide ion (O2·-), the former of which oxidizes 1, while O2·- reacts with the resulting 1·+ to give the major oxidation products.
- Mori, Tadashi,Takamoto, Makoto,Tate, Yoshimasa,Shinkuma, Junya,Wada, Takehiko,Inoue, Yoshihisa
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- Hybrid mesoporous-silica materials functionalized by PtII complexes: Correlation between the spatial distribution of the active center, photoluminescence emission, and photocatalytic activity
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[Pt(tpy)Cl]Cl (tpy: terpyridine) was successfully anchored to a series of mesoporous-silica materials that were modified with (3-aminopropyl) triethoxysilane with the aim of developing new inorganic-organic hybrid photocatalysts. Herein, the relationship between the luminescence characteristics and photocatalytic activities of these materials is examined as a function of Pt loading to define the spatial distribution of the Pt complex in the mesoporous channel. At low Pt loading, the Pt complex is located as an isolated species and exhibits strong photoluminescence emission at room temperature owing to metal-to-ligand charge-transfer (3MLCT) transitions (at about 530 nm). Energy- and/or electron-transfer from 3MLCT to O2 generate potentially active oxygen species, which are capable of promoting the selective photooxidation of styrene derivatives. On the other hand, short Pt...Pt interactions are prominent at high loading and the metal-metal-to-ligand charge-transfer (3MMLCT) transition is at about 620 nm. Such Pt complexes, which are situated close to each other, efficiently catalyze H2-evolution reactions in aqueous media in the presence of a sacrificial electron donor (EDTA) under visible-light irradiation. This study also investigates the effect of nanoconfinement on anchored guest complexes by considering the differences between the pore dimensions and structures of mesoporous-silica materials. Anchorman: [Pt(tpy)Cl]Cl (tpy: terpyridine) was anchored to a series of mesoporous-silica materials that were modified with (3-aminopropyl)trimethoxysilane to afford new inorganic-organic hybrid photocatalysts (see graphic). Copyright
- Mori, Kohsuke,Watanabe, Kentaro,Terai, Yoshikazu,Fujiwara, Yasufumi,Yamashita, Hiromi
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p. 11371 - 11378,8
(2012)
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- An efficient biomimetic Fe-catalyzed epoxidation of olefins using hydrogen peroxide
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A new, environmentally benign and practical epoxidation method was developed using inexpensive and efficient Fe catalysts. FeCl3· 6H2O in combination with commercially available pyridine-2,6- dicarboxylic acid and amines showed excellent reactivity and selectivity towards aromatic olefins and moderate reactivity towards 1,3-cyclooctadiene utilizing H2O2 as the terminal oxidant. The Royal Society of Chemistry.
- Anilkumar, Gopinathan,Bitterlich, Bianca,Gelalcha, Feyissa Gadissa,Tse, Man Kin,Beller, Matthias
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- Synthesis, structural characterization and catalytic potential of oxidovanadium(IV) and dioxidovanadium(V) complexes with thiazole-derived NNN-donor ligand
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Reaction between the tridentate NNN donor ligand, (E)-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)benzo[d]thiazole (HL), and V2O5 in ethanol gave a new vanadium(V) complex, [VO2L] (1), while the similar reaction by using [VIVO(acac)2] as the metal source gave two different types of crystals related to compounds [VO2L] (1) and [VIVO(acac)L] (2). The molecular structures of the complexes were determined by single-crystal X-ray diffraction and spectroscopic characterization was carried out by means of FT-IR, UV–vis and NMR experiments as well as elemental analysis. The oxidovanadium(IV) and dioxidovanadium(V) species were used as catalyst precursors for olefin oxidation in the presence of hydrogen peroxide (H2O2) as an oxidant. Under similar experimental conditions, the presence of 1 resulted in higher oxidation conversion than 2.
- Ghorbanloo, Massomeh,Bikas, Rahman,Jafari, Solmaz,Krawczyk, Marta S.,Lis, Tadeusz
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- The in situ generation and use of iodomethyllithium for the one-carbon homologation of boronic esters and epoxide formation from carbonyl compounds
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Iodomethyllithium is shown to be an effective reagent for the one-carbon homologation of oxygenated boronic esters. The use of iodomethyllithium for the preparation of pinacol iodomethaneboronate and for the synthesis of epoxides from carbonyl compounds is also discussed.
- Wallace,Battle
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- Graphene oxide nanosheets supported manganese(III) porphyrin: a highly efficient and reusable biomimetic catalyst for epoxidation of alkenes with sodium periodate
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Efficient epoxidation of alkenes catalyzed by tetrakis(p-aminophenyl)porphyrinatomanganese(III) chloride, [Mn(TNH2PP)Cl], supported on graphene oxide nanosheets, is reported. The catalyst, [Mn(TNH2PP)Cl]@GO, was prepared by covalent attachment of amino groups of porphyrin to carboxylic acid groups of GO. This new heterogenized catalyst was characterized by ICP, FT-IR and diffuse reflectance UV–vis spectroscopies, scanning electron microscopy and transmission electron microscopy. This catalyst was applied as an efficient and reusable catalyst in the epoxidation of alkenes with NaIO4 at room temperature, in the presence of imidazole as axial ligand. The most noteworthy advantage of [Mn(TNH2PP)Cl]@GO is its high reusability in the oxidation reactions, in which the catalyst was reused several times without significant loss of its catalytic activity.
- Zarrinjahan, Alireza,Moghadam, Majid,Mirkhani, Valiollah,Tangestaninejad, Shahram,Mohammadpoor-Baltork, Iraj
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- Synthesis of a new schiff base oxovanadium complex with melamine and 2-hydroxynaphtaldehyde on modified magnetic nanoparticles as catalyst for allyl alcohols and olefins epoxidation
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A new magnetically recoverable nanocatalyst designated as Fe3O4@SiO2@PTMS@Mel-Naph-VOcomplex was synthesize by covalent binding of a Schiff base ligand derived from melamine and 2-hydroxy1naphtaldehyde on the surface of silica coated iron oxide magnetic nanoparticles followed by complexation with VO (acac)2. Characterization of the prepared nanocatalyst was accomplished with FT-IR, XRD, SEM, HRTEM, VSM and atomic absorption techniques. It was found that the epoxidation of geraniol, trans-2-hexen-1-ol, 1-octen-3-ol, norbornene, and cyclooctene is highly selective, affording quantitative yields of the corresponding epoxides with tert-butyl hydroperoxide (TBHP) using Fe3O4@SiO2@Mel-Naph-VOcomplex as catalyst. High reaction yields, short reaction times, simple experimental and work up procedure, catalyst stability and excellent reusability even after five-cycles of usage in the case of geraniol are some advantages of this research.
- Farzaneh, Faezeh,Asgharpour, Zeinab
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- Asymmetric epoxidation of unfunctionalized alkenes catalyzed by sugar moiety-modified chiral salen-Mn(III) complexes
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Several chiral Schiff-base ligands with sugar moieties at C-3 (3′) or C-5 (5′) of salicylaldehyde were synthesized from reaction of salicylaldehyde derivatives with diamine. These ligands coordinated with Mn(III) to afford the corresponding chiral salen-M
- Zhao, Jiquan,Zhang, Yuecheng,Han, Furong,Zhao, Shanshan
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- Substituted perhydrofuropyrans: Easy preparation from 2-chloromethyl-3- (2-methoxyethoxy)propene through 3-methylene-1,6-diols
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The reaction of 2-chloromethyl-3-(2-methoxyethoxy)prop-1-ene (1) with an excess of lithium powder and a catalytic amount of naphthalene (2.5%) in the presence of a carbonyl compound (E1=R1R2CO) in THF at -78 to 0°C, followed by treatment with an epoxide [E2=R3R4C(O)CHR5] at 0 to 20°C leads, after hydrolysis, to the expected unsaturated diols 2. When some compounds 2 (2e-h) are successively hydroborated (BH3 · THF) and oxidised (33% H2O2 and then PCC), the expected perhydrofuropyrans 3e-h are isolated directly. (C) 2000 Elsevier Science Ltd.
- Lorenzo, Emilio,Alonso, Francisco,Yus, Miguel
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- Photoinduced electron-transfer oxidation of olefins with molecular oxygen sensitized by tetrasubstituted dimethoxybenzenes: A non-singlet-oxygen mechanism
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α-Methylstyrene (1) was photo-oxidized in the presence of a series of alkylated dimethoxybenzenes as sensitizers in an oxygen-saturated MeCN solution to afford the cleaved ketone 2, epoxide 3, as well as a small amount of the ene product 4 in ca. 1:1:0.04 ratio. The relative rate of conversion was well-correlated with the fluorescence quantum yield of sensitizers. Thus, a non-singlet-oxygen mechanism is proposed, in which an excited sensitizer is quenched by (ground-state) molecular oxygen to produce a sensitizer radical cation and a superoxide ion (O2-·), the former of which oxidizes the substrate, while the latter reacts with the resulting olefin radical cation (1-·) to give the major oxidation products. Photodurability of such electron-donating sensitizers is dramatically improved by substituting four aromatic H-atoms in 1,4-dimethoxybenzene with Me or fused alkyl groups, which provides us with an environmentally friendly, clean method of photochemical functionalization with molecular oxygen, alternative to the ene reaction via singlet oxygenation.
- Mori, Tadashi,Takamoto, Makolo,Wada, Takehiko,Inoue, Yoshihisa
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- A novel strategy for clean and selective oxygenation of hydrocarbons with n-Bu4NHSO5 in neat water catalyzed by recyclable water-insoluble iron (III) tetraphenylporphyrins
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A novel heterogeneous method for efficient oxygenation of olefins to epoxides and saturated hydrocarbons to the related ketones using tetrabutylammonium peroxomonosulfate (n-Bu4NHSO5) in neat water catalyzed by Fe(TPP)Cl and Fe(TDCPP)Cl complexes as water-insoluble catalysts has been developed. The oxidation system proceeds well in the absence of organic co-solvents and surfactants. The electron-deficient Fe(TDCPP)Cl catalyst could easily be recycled and reused without loss of activity and the oxidant's by-product (n-Bu4NHSO4) could also be recycled.
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Naeimi, Atena,Kaafi, Samira
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- Epoxidation of alkenes with NaIO4 catalyzed by an efficient and reusable natural polymer-supported ruthenium(III) salophen catalyst
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In the present study, preparation, characterization, and catalytic activity of Ru(salophen)Cl supported on chitosan were investigated. The prepared heterogeneous catalyst was characterized by diffuse reflectance UV-vis and FT-IR spectroscopic techniques, scanning electron microscopy, and neutron activation analysis. In this catalytic system, the effects of different solvents were studied in the epoxidation of cis-cyclooctene and CH3CN/H2O was found to be a better solvent. Also, the effects of oxygen donors such as NaIO4, H2O2, H2O2/urea(UHP), tert-BuOOH, NaClO, and Bu4NIO4 were studied in the epoxidation of cis-cyclooctene and NaIO4 was selected as an oxidant. The catalytic activity of this new heterogeneous catalyst in the epoxidation of cyclic and linear alkenes using NaIO4 as an oxidant in CH3CN/H2O at room temperature was studied. The obtained results led us to conclude that [Ru(salophen)Cl@ chitosan] is an efficient catalyst for the epoxidation of alkenes with NaIO4. The catalyst can be readily recovered simply by filtration and reused several times without any significant loss in its catalytic activity.
- Hatefi Ardakani,Moghadam,Saeednia,Pakdin-Parizi
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- MoO2(acac)2 supported on multi-wall carbon nanotubes: Highly efficient and reusable catalysts for alkene epoxidation with tert-BuOOH
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In the present work, the preparation, characterization and investigation of the catalytic activity of MoO2(acac)2 supported on multi-wall carbon nanotubes modified with 2-aminopyridine and 1,2-diaminobenzene are reported. The catalysts were characterized by elemental analysis, FT-IR and UV-Vis spectroscopic techniques and scanning electron microscopy (SEM). The catalytic activity of molybdenyl acetylacetonate supported on multi-wall carbon nanotubes, MoO2(acac)@amine-MWCNTs, was investigated in the alkene epoxidation with tert-BuOOH. These heterogenized catalysts were successfully applied for efficient epoxidation of olefins with tert-BuOOH in 1,2-dichloroethane as the solvent. The prepared catalysts can be reused several times without significant loss of their catalytic activity.
- Esnaashari, Fariba,Moghadam, Majid,Mirkhani, Valiollah,Tangestaninejad, Shahram,Mohammadpoor-Baltork, Iraj,Khosoropour, Ahmad Reza,Zakeri, Maryam,Hushmandrad, Shohreh
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- Manganese(II) complexes of hydrazone based NNO-donor ligands and their catalytic activity in the oxidation of olefins
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The reaction between tridentate NNO donor hydrazone ligands, (E)-2-cyano-N′-(phenyl(pyridin-2-yl)methylene)acetohydrazide (HL1) and (E)-2-cyano-N′-(1-(pyridin-2-yl)ethylidene)acetohydrazide (HL2), with MnCl2·4H2O in methanol resulted in [Mn(HL1)Cl2(CH3OH)] (1) and [Mn(HL2)Cl2(CH3OH)] (2). Molecular structures of the complexes were determined by single-crystal X-ray diffraction. All of the investigated compounds were further characterized by elemental analysis, FT-IR, TGA, and UV–Vis spectroscopy. These complexes were used as catalysts for olefin oxidation in the presence of tert-butylhydroperoxide (TBHP) as an oxidant. Under similar experimental conditions with equal manganese loading, the presence of [Mn(HL2)Cl2(CH3OH)] (2) resulted in higher conversion than [Mn(HL1)Cl2(CH3OH)] (1).
- Bikas, Rahman,Ghorbanloo, Massomeh,Sasani, Roya,Pantenburg, Ingo,Meyer, Gerd
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- Catalytic activity of carbon nanotube supported iron(III) and manganese(III) porphyrins in oxidation of olefins with tert-butyl hydroperoxide: Higher activity of the iron(III) porphyrin
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Oxidation of olefins with tert-butyl hydroperoxide (TBHP) catalyzed by carbon nanotube supported iron(III) and manganese(III) complexes of meso-tetrakis(4-hydroxyphenyl)porphyrin is reported. The results show higher catalytic activity of the Fe(III) complex compared to the Mn(III) one. With the exception of cyclooctene which gives cyclooctene oxide as the sole product, oxidation of styrene, α-methyl styrene and cyclohexene leads to the formation of benzaldehyde, acetophenone and cyclohexene-1-one as the major product, respectively. In this study, acetonitrile has been found to be the best solvent for reaction performed in the presence of the manganese and iron porphyrin. In comparison of the two metalloporphyrins, catalytic activity of the manganese porphyrin is more sensitive to the type of solvent than the iron one. In spite of the crucial role of imidazole (ImH) on catalytic performance of the manganese porphyrin, the presence of ImH has a negative effect on the activity of the iron porphyrin. The nano-tube supported iron porphyrin may be recovered and reused at least four times without significant loss of the catalytic activity.
- Rayati, Saeed,Jafarzadeh, Parisa,Zakavi, Saeed
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- Nickel complexes with N2O donor ligands: Syntheses, structures, catalysis and magnetic studies
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Two new terephthalato-bridged tetranuclear polymeric NiII complexes, namely [Ni4L41(μ-tp- κ4-O)(H2O)2(μ-tp-κ2- O)]· 2C2H5OH·CH3OH·3H 2O (1) and [Ni4L42(μ-tp- κ4-O)(H2O)2(μ-tp-κ2- O)]·3H2O (2) [L1 = N-(3-aminopropyl)-5- bromosalicylaldimine and L2 = N-(3-aminopropyl)salicylaldimine], are reported along with the syntheses and structures of the dicyanoargentate-bridged polymeric complexes [Ni(L1)(H2O)-{Ag(CN) 2}]α (3) and [Ni(L3)(MeOH){Ag(CN) 2}]α (4) [L3 = N-(3-amino-2,2-dimethylpropyl)-5- bromosalicylaldimine]. All four complexes are found to be effective heterogeneous catalysts for the epoxidation of alkenes such as styrene, α-methylstyrene and cyclohexene in the presence of tert-butyl hydroperoxide. The variable-temperature magnetic susceptibility measurements (300-2 K) of complex 1 show a fair degree of antiferromagnetic coupling between the NiII centers. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Chakraborty, Jishnunil,Nandi, Mahasweta,Mayer-Figge, Heike,Sheldrick, William S.,Sorace, Lorenzo,Bhaumik, Asim,Banerjee, Pradyot
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- AuCu/ZnO heterogeneous photocatalysts: Photodeposited AuCu alloy effect on product selectivity in alkene epoxidation
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AuCu metal alloy nanoparticles were photodeposited on ZnO nanorods (ZnO_NRs) which proved to be effective photocatalysts for alkene epoxidation. The alloy nanoparticles were photodeposited onto ZnO nanorods with controlled ratios of gold and copper, with the deposition monitored in situ by UV-Vis spectroscopy. The alloy catalyst hybrids were tested for activity toward styrene epoxidation and HMF oxidative esterification, where the photoreactions were both optimized for time, temperature, and metal ratio content of the catalyst. The Au0.54Cu1/ZnO_NR alloy catalysts showed excellent photocatalytic activity and were most effective for conversion of styrene to styrene epoxide, where the product selectivity could be controlled by varying the metal ratio. Cu content in the alloy NP was essential to this process, as shown by the extrema in terms of metal content, using Au/ZnO only, where 100% benzaldehyde was obtained as the product. Au/ZnO evidenced best photocatalytic activity for HMF esterification, with conversion rapidly diminishing upon alloying of Au with Cu. A detailed XPS study was carried out to investigate reaction mechanism based on these studies, in particular, mechanisms are proposed for styrene epoxidation and oxidation cycles using the AuCu/ZnO_NR photocatalysts.
- Brock, Aidan J.,Deshan, Athukoralalage Don K.,Sarina, Sarina,Waclawik, Eric R.,Weerathunga, Helapiyumi,Zhu, Huai-Yong
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- Chiral porous poly(ionic liquid)s: Facile one-pot, one-step synthesis and efficient heterogeneous catalysts for asymmetric epoxidation of olefins
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Ionic liquids are potential media/solvents for asymmetric synthesis when combined with chiral catalysts, while most reported catalysts are homogenous, making them difficult to separate from the reaction systems. Herein, chiral porous poly(ionic liquid)s (
- Tian, Yabing,Wang, Jixia,Zhang, Shiguo,Zhang, Yan
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- Aerobic epoxidation of styrene over Zr-based metal-organic framework encapsulated transition metal substituted phosphomolybdic acid
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Catalytic epoxidation of styrene with molecular oxygen is regarded as an eco-friendly alternative to producing industrially important chemical of styrene oxide (STO). Recent efforts have been focused on developing highly active and stable heterogeneous catalysts with high STO selectivity for the aerobic epoxidation of styrene. Herein, a series of transition metal monosubstituted heteropolyacid compounds (TM-HPAs), such as Fe, Co, Ni or Cu-monosubstituted HPA, were encapsulated in UiO-66 frameworks (denoted as TM-HPA@UiO-66) by direct solvothermal method, and their catalytic properties were investigated for the aerobic epoxidation of styrene with aldehydes as co-reductants. Among them, Co-HPA@UiO-66 showed relatively high catalytic activity, stability and epoxidation selectivity at very mild conditions (313 K, ambient pressure), that can achieve 82 % selectivity to STO under a styrene conversion of 96 % with air as oxidant and pivalaldehyde (PIA) as co-reductant. In addition, the hybrid composite catalyst can also efficiently catalyze the aerobic epoxidation of a variety of styrene derivatives. The monosubstituted Co atoms in Co-HPA@UiO-66 are the main active sites for the aerobic epoxidation of styrene with O2/PIA, which can efficiently converting styrene to the corresponding epoxide through the activation of the in-situ generated acylperoxy radical intermediate.
- Hu, Dianwen,Song, Xiaojing,Zhang, Hao,Chang, Xinyu,Zhao, Chen,Jia, Mingjun
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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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- 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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- Aldehyde-catalyzed epoxidation of unactivated alkenes with aqueous hydrogen peroxide
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The organocatalytic epoxidation of unactivated alkenes using aqueous hydrogen peroxide provides various indispensable products and intermediates in a sustainable manner. While formyl functionalities typically undergo irreversible oxidations when activating an oxidant, an atropisomeric two-axis aldehyde capable of catalytic turnover was identified for high-yielding epoxidations of cyclic and acyclic alkenes. The relative configuration of the stereogenic axes of the catalyst and the resulting proximity of the aldehyde and backbone residues resulted in high catalytic efficiencies. Mechanistic studies support a non-radical alkene oxidation by an aldehyde-derived dioxirane intermediate generated from hydrogen peroxide through the Payne and Criegee intermediates.
- Kokotos, Christoforos G.,Kokotou, Maroula G.,Lotter, Dominik,Sparr, Christof,Triandafillidi, Ierasia
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p. 10191 - 10196
(2021/08/12)
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- A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles
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A new heterogeneous catalytic system consisting of cobalt nanoparticles (CoNPs) supported on MgO and tert-butyl hydroperoxide (TBHP) as oxidant is presented. This CoNPs@MgO/t-BuOOH catalytic combination allowed the epoxidation of a variety of olefins with good to excellent yield and high selectivity. The catalyst preparation is simple and straightforward from commercially available starting materials and it could be recovered and reused maintaining its unaltered high activity.
- Rossi-Fernández, Lucía,Dorn, Viviana,Radivoy, Gabriel
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supporting information
p. 519 - 526
(2021/03/31)
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- Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides
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The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.
- Lambert, Tristan H.,Steiniger, Keri A.
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supporting information
p. 8013 - 8017
(2021/10/25)
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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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- Formation of β-Ga2O3nanorings from metal-organic frameworks and their high catalytic activity for epoxidation of alkenes
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Here we report a novel synthesis of hollow high-quality β-Ga2O3 nanorings based on an interesting structural evolution from concave Ga-MOF nanodisks. The concave low-crystallinity nanodisks were constructed by non-classical crystallization with particle a
- Wang, Wei Ping,Song, Le Xin,Li, Yao,Teng, Yue,Xia, Juan,Wang, Fang,Liu, Nan Ning
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p. 349 - 357
(2021/01/14)
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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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- Asymmetric azidohydroxylation of styrene derivatives mediated by a biomimetic styrene monooxygenase enzymatic cascade
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Enantioenriched azido alcohols are precursors for valuable chiral aziridines and 1,2-amino alcohols, however their chiral substituted analogues are difficult to access. We established a cascade for the asymmetric azidohydroxylation of styrene derivatives leading to chiral substituted 1,2-azido alcohols via enzymatic asymmetric epoxidation, followed by regioselective azidolysis, affording the azido alcohols with up to two contiguous stereogenic centers. A newly isolated two-component flavoprotein styrene monooxygenase StyA proved to be highly selective for epoxidation with a nicotinamide coenzyme biomimetic as a practical reductant. Coupled with azide as a nucleophile for regioselective ring opening, this chemo-enzymatic cascade produced highly enantioenriched aromatic α-azido alcohols with up to >99% conversion. A bi-enzymatic counterpart with halohydrin dehalogenase-catalyzed azidolysis afforded the alternative β-azido alcohol isomers with up to 94% diastereomeric excess. We anticipate our biocatalytic cascade to be a starting point for more practical production of these chiral compounds with two-component flavoprotein monooxygenases.
- Franssen, Maurice C. R.,Hollmann, Frank,Martínez-Montero, Lía,Paul, Caroline E.,Süss, Philipp,Schallmey, Anett,Tischler, Dirk
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p. 5077 - 5085
(2021/08/16)
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- Facile synthesis of libraries of functionalized cyclopropanes and oxiranes using ionic liquids – A new approach to the classical Corey-Chaykovsky reaction
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The potential of [PAIM][NTf2]/BMIM-ILs as a base/solvent in the Corey-Chaykovsky reaction is demonstrated by the facile synthesis of libraries of functionalized cyclopropanes from enones and oxiranes from aldehydes and ketones, at room temperature in respectable isolated yields. To demonstrate their application, the synthesized epoxides were employed as substrates for the synthesis of a library of 2,3-disubstituted quinolines, using [BMIM(SO3H)][OTf]/[BMIM][PF6] as a catalyst/solvent. The potential for recycling/reuse of the IL solvents was also explored.
- Malunavar, Shruti S.,Sutar, Suraj M.,Prabhala, Pavankumar,Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Aridoss, Gopalakrishnan,Laali, Kenneth K.
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supporting information
(2021/09/13)
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- Synthesis and characterization of molybdenum (VI) complex immobilized on polymeric Schiff base-coated magnetic nanoparticles as an efficient and retrievable nanocatalyst in olefin epoxidation reactions
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In this study, a new polymeric functionalized magnetic nanocatalyst containing a molybdenum Schiff base complex was prepared using a few consecutive steps. Poly (methylacrylate)-coated magnetic nanoparticles were synthesized via radical polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the amidation of the methyl ester groups with hydrazine. Polymeric functionalization efficiently provides the advantage that more catalytic units can be grafted on the surface of magnetic nanoparticles. The functionalization process was continued with salicylaldehyde which introduced Schiff base groups on to the surface of the polymeric support. In the final step, the desired catalytic system was prepared via complexation of the Schiff base groups with MoO2(acac)2. The resulting nanoparticles were characterized by infrared spectroscopy, powder X-ray diffraction, scanning and transmission electron microscopy, elemental analysis, inductively coupled plasma optical emission spectrometry, vibrating sample magnetometry and thermogravimetric analysis. This heterogenized catalytic system was also found to be highly active, sustainable and recyclable nanocatalyst in alkene epoxidation. Eventually, the attractive features of the synthesized catalyst such as simple work-up, good stability, magnetic separation, high TOF and high surface area; make it appropriate for oxidation reactions.
- Mortazavi-Manesh, Anahita,Bagherzadeh, Mojtaba
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- The big effect of a small change: formation of CuO nanoparticles instead of covalently bound Cu(ii) over functionalized mesoporous silica and its impact on catalytic efficiency
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Two different heterogeneous catalysts, one with Cu(ii) covalently bonded to functionalized mesoporous silica (FMS-Cu(II)) and another with CuO nanoparticles immobilized over the same silica (FMS-CuO-np), have been synthesized by a common route but with a minor alteration in the sequence of addition of reagents. It is interesting to find that by merely changing the order of the addition of reagents Cu(ii) can be incorporated into the framework in two different forms. In one case Cu(ii) binds to the N and O donor centers present in the functionalized material whereas in the other case CuO nanoparticles are generated in situ. The materials have been thoroughly characterized by powder X-ray diffraction, nitrogen adsorption/desorption, transmission electron microscopy, thermal analysis, FT-IR spectroscopy, solid state MAS-NMR spectroscopy and atomic absorption spectrophotometric studies. The synthesized products have been examined for their catalytic efficiencies in the oxidation of olefins, as a model case. Styrene, α-methyl styrene, cyclohexene, trans-stilbene and cyclooctene have been used as substrates in the presence of tert-butyl hydroperoxide as the oxidant in acetonitrile medium under mild conditions. The products of the catalytic reactions have been identified and estimated by gas chromatography and gas chromatography-mass spectrometry. The rate of conversion of the substrates for both the catalysts is high and the selectivity is also good. But from comparative studies, it is found that FMS-CuO-np which contains CuO nanoparticles shows better efficiency than FMS-Cu(II). The catalysts have been recycled for five catalytic cycles without showing much decrease in their catalytic activity. This journal is
- Das, Trisha,Nandi, Mahasweta,Singha, Debdas
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p. 10138 - 10155
(2020/08/17)
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- Magnetically recoverable porphyrin-based nanocatalysts for the effective oxidation of olefins with hydrogen peroxide: A comparative study
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In this paper, preparation, characterization and catalytic applications of metalloporphyrin-based magnetic nanocatalysts were investigated. meso-Tetrakis(4-carboxyphenyl)porphyrinatoiron(iii) chloride (Fe(TCPP)Cl) and meso-tetrakis(4-carboxyphenyl)porphyrinatomanganese(iii) acetate (Mn(TCPP)OAc) were separately immobilized onto the surface of amine functionalized magnetic nanoparticles (Fe3O4/SiO2/NH2) via covalent attachment. The obtained nanocatalysts were characterized using FT-IR and UV-Vis and atomic absorption spectroscopy, X-ray powder diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The catalytic efficiency of Fe3O4/SiO2/NH2-Fe(TCPP)Cl and Fe3O4/SiO2/NH2-Mn(TCPP)OAc for the green oxidation of alkenes with H2O2 was investigated in a comparative manner. The Mn-porphyrin based magnetic nanocatalyst shows higher catalytic efficiency compared to the Fe-porphyrin. In addition, the prepared magnetic nanocatalyst exhibited excellent reusability and could be reused at least five times without significant leaching or loss of activity. This journal is
- Rayati, Saeed,Moradi, Dana,Nejabat, Fatemeh
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p. 19385 - 19392
(2020/11/23)
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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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- 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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- Synthesis method and application of sulfo-group-containing sulfur ylide
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A synthesis method of sulfo-group-containing sulfur ylide comprises the following steps: reacting synthesized sulfonate represented by formula (IV) with a methylation reagent at 220-260 DEG C for 1-6h to obtain sulfur ylide represented by formula (III) when the reaction is finished; and carrying out an epoxidation reaction on the sulfur ylide of formula (III) and carbonyl compounds represented byformula (II) in a solvent at a reaction temperature of 40-60 DEG C for 1-7 h under the action of an alkaline substance, carrying out post-treatment on the reacted solution to obtain an oxirane derivative represented by formula (I), and simultaneously treating and recovering the generated protosolid sulfonate. The invention also discloses an application of the sulfo-group-containing sulfur ylide.The product is small in irritation and easy to be dissolved in water; and when the product is applied to the epoxidation reaction, the raw material alkyl sulfonate can be recycled, so that the industrial cost is reduced, and the production efficiency is improved.
- -
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Paragraph 0033; 0036; 0038; 0041; 0042; 0045; 0046; 0049
(2020/05/30)
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- Selective Functionalization of Styrenes with Oxygen Using Different Electrode Materials: Olefin Cleavage and Synthesis of Tetrahydrofuran Derivatives
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Electrode materials can have a significant impact on the course of an electrolysis reaction. Of particular interest is that different electrodes can generate different products from the same substrate. The electrode-material-selective transformations of styrene derivatives with molecular oxygen are reported. Platinum electrodes afford carbonyl products via cleavage of olefins, whereas tetrahydrofuran formation is achieved with carbon electrodes. A variety of different styrenes are available for both reactions. Electrolysis allows straightforward and mild chemical conversions that are metal- and oxidant-free. Electrochemical measurements illuminate the different effects of platinum and carbon electrodes on styrenes. The key to the differing reactions is probably that the oxidation potentials of the substrates are lower (higher HOMO energy) on carbon electrodes than on platinum electrodes. The adsorption of the substrates on carbon electrodes can also promote tetrahydrofuran formation.
- Imada, Yasushi,Okada, Yohei,Noguchi, Keiichi,Chiba, Kazuhiro
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supporting information
p. 125 - 129
(2018/12/05)
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- Preparation and characterization of Fe3O4@Boehmite core-shell nanoparticles to support molybdenum or vanadium complexes for catalytic epoxidation of alkenes
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Fe3O4 core nanoparticles were prepared via a solvothermal process, and then they were covered with a surface hydroxyl-rich boehmite shell via the hydrothermal-assisted sol–gel processing of aluminum 2-propoxide. The outer surface of the boehmite shell was subsequently covalently functionalized with 3-(tri-methoxysilyl)-propylamine or 3-(tri-methoxysilyl)-propyl chloride, and the terminal chlorine groups were treated with imidazole. These compounds were used to support the hexa-carbonyl molybdenum and oxo-sulfato vanadium (IV) complexes. The supported catalysts were characterized by the FT-IR, CHN, ICP, and TEM analysis techniques. They were then used in the epoxidation of cis-cyclooctene. The catalytic procedures were optimized for different parameters such as the solvent, oxidant, and temperature. The reaction progress was investigated by the gas–liquid chromatography analysis. The catalysts used were simply recovered from the solution by applying a magnet, and recycling the experiments revealed that the heterogeneous nanocatalysts could be repeatedly used for the epoxidation of cis-cyclooctene. The optimized conditions were also successfully used for the epoxidation of some other alkenes.
- Mirzaee, Mahdi,Bahramian, Bahram,Gholampour, Parichehr,Teymouri, Samaneh,Khorsand, Toktam
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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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- Retro-Corey-Chaykovsky Epoxidation: Converting Geminal Disubstituted Epoxides to Ketones
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Corey-Chaykovsky epoxidation has been widely applied in the conversion of aldehydes and ketones to epoxides with sulfonium and sulfoxonium ylides. The reverse transformation is realized for conversion of geminal disubstituted epoxides to ketones in the presence of DABCO in refluxing mesitylene. The method is a weak basic transformation from epoxides to ketones with loss of a methylene group and can be applied as an alternative strategy of the acid-catalyzed Meinwald rearrangement or oxidation for conversion of epoxides to carbonyl compounds.
- Li, Siqi,Li, Pingfan,Xu, Jiaxi
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- Asymmetric epoxidation of unfunctionalized olefins with C2-symmetrical diphenol-derived axially coordinated homogeneous chiral bi-Mn(III) salen complexes
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A novel type of C2-symmetrical diphenol-derived and axially coordinated homogeneous chiral bi-Mn(III) salen complexes are synthesized and their catalytic effects in asymmetric epoxidation of unfunctionalized olefins are investigated in details. The results show that excellent enantioselectivities and high activities are achieved (enantioselectivities up to >99% in 99.9%) in the absence of expensive NMO. Compared with Jacobsen's catalyst, the configuration of C2-symmetrical homogeneous chiral bi-Mn(III) salen complex contribute to the catalytic reactivity and stability. Furthermore, these new homogeneous catalysts could be easily recovered and reused for 5 cycles without significant loss of their properties.
- Dong, Tianyi,Wu, Xiaoju,Cai, Jiali,Huang, Jing
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- Peroxygenase-Catalysed Epoxidation of Styrene Derivatives in Neat Reaction Media
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Biocatalytic oxyfunctionalisation reactions are traditionally conducted in aqueous media limiting their production yield. Here we report the application of a peroxygenase in neat reaction conditions reaching product concentrations of up to 360 mM.
- Alcalde, Miguel,Arends, Isabel W. C. E.,Hollmann, Frank,Paul, Caroline E.,Rauch, Marine C. R.,Tieves, Florian
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- Mild Iridium-Catalysed Isomerization of Epoxides. Computational Insights and Application to the Synthesis of β-Alkyl Amines
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The isomerization of epoxides to aldehydes using the readily available Crabtree's reagent is described. The aldehydes were transformed into synthetically useful amines by a one-pot reductive amination using pyrrolidine as imine-formation catalyst. The reactions worked with low catalyst loadings in very mild conditions. The procedure is operationally simple and tolerates a wide range of functional groups. A DFT study of its mechanism is presented showing that the isomerization takes place via an iridium hydride mechanism with a low energy barrier, in agreement with the mild reaction conditions. (Figure presented.).
- Cabré, Albert,Cabezas-Giménez, Juanjo,Sciortino, Giuseppe,Ujaque, Gregori,Verdaguer, Xavier,Lledós, Agustí,Riera, Antoni
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supporting information
p. 3624 - 3631
(2019/07/10)
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- Chiral salen Mn (III) immobilized on ZnPS-PVPA through alkoxyl-triazole for superior performance catalyst in asymmetric epoxidation of unfunctionalized olefins
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Chiral salen Mn (III) catalysts anchored onto ZnPS-PVPA via click chemistry are prepared and applied in asymmetric epoxidations of unfunctionalized olefins. Superior catalytic performances (conv%, up to >99; ee%, up to >99) are achieved in the epoxidations of α-methylstyrene, styrene, indene and 1-octene. According to 6-cyano-2,2-dimethylchromene and 6-nitro-2,2-dimethylchromene, configuration of epoxides are reversed. And then the catalysts are selective in not only oxidative systems, but also substrates. Moreover, superior reusability (yield, 82%; ee, 86%) after recycling for nine times could also be obtained, which provide the potential application in industry.
- Huang, Jing,Liu, Sirui,Ma, Yan,Cai, Jiali
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supporting information
p. 27 - 33
(2019/02/28)
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- Unprecedented Asymmetric Epoxidation of Isolated Carbon–Carbon Double Bonds by a Chiral Fluorous Fe(III) Salen Complex: Exploiting Fluorophilic Effect for Catalyst Design
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The first asymmetric epoxidation of isolated carbon–carbon double bonds by a chiral salen complex using ubiquitous Fe(III) as a center-metal is described. By simultaneously introducing fluorous tags and tert-butyl groups into the ligand of the salen compl
- Kobayashi, Yuki,Obayashi, Riho,Watanabe, Yuki,Miyazaki, Hiroki,Miyata, Issei,Suzuki, Yuta,Yoshida, Yukihiro,Shioiri, Takayuki,Matsugi, Masato
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supporting information
p. 2401 - 2408
(2019/03/26)
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- Asymmetric epoxidation of unfunctionalized olefins catalyzed by chiral salen-Mn (III) immobilized on alkoxyl-modified ZnPS-PVPA
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Novel layered heterogeneous chiral salen Mn (III) catalysts anchored onto ZnPS-PVPA by means of click chemistry are synthesized and employed in asymmetric epoxidations of unfunctionalized olefins. The catalysts manifest superior catalytic performances (conv%, up to >99; ee%, up to >99) according to the epoxidations of α-methylstyrene, styrene, indene and 1-octene. But for 6-cyano- 2,2-dimethylchromene and 6-nitro-2,2-dimethylchromene, configuration of epoxides are reversed. Moreover, the catalysts could still indicate comparable properties (yield, 82%; ee, 86%) after recycling for nine times and excellent functions in large-scale reactions, which paves the way for the application in industry.
- Huang, Jing,Xie, Junjie,Cai, Jiali
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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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- Biomimetic non-heme iron-catalyzed epoxidation of challenging terminal alkenes using aqueous H2O2 as an environmentally friendly oxidant
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Catalysis mediated by iron complexes is emerging as an eco-friendly and inexpensive option in comparison to traditional metal catalysis. The epoxidation of alkenes constitutes an attractive application of iron(III) catalysis, in which terminal olefins are challenging substrates. Herein, we describe our study on the design of biomimetic non-heme ligands for the in situ generation of iron(III) complexes and their evaluation as potential catalysts in epoxidation of terminal olefins. Since it is well-known that active sites of oxidases might involve imidazole fragment of histidine, various simple imidazole derivatives (seven compounds) were initially evaluated in order to find the best reaction conditions and to develop, subsequently, more elaborated amino acid-derived peptide-like chiral ligands (10 derivatives) for enantioselective epoxidations.
- Fingerhut, Anja,Vargas-Caporali, Jorge,Leyva-Ramírez, Marco Antonio,Juaristi, Eusebio,Tsogoeva, Svetlana B.
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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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- Continuous Flow Synthesis of Terminal Epoxides from Ketones Using in Situ Generated Bromomethyl Lithium
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A scalable procedure for the direct preparation of epoxides from ketones has been developed. The method is based on the carefully controlled generation of (bromomethyl)lithium (LiCH2Br) from inexpensive CH2Br2 and MeLi in a continuous flow reactor. The reaction has shown excellent selectivity for a variety of substrates, including α-chloroketones, which typically fail under classic Corey-Chaykovsky conditions. This advantage has been used to develop a novel route toward the drug fluconazole.
- Von Keutz, Timo,Cantillo, David,Kappe, C. Oliver
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supporting information
p. 10094 - 10098
(2019/12/24)
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- Selective catalytic oxidation of aromatic substrates employing mononuclear copper(II) catalyst with H2O2
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A novel mononuclear complex [LCuCl2(H2O)]CH2Cl2 (L = 2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine) was synthesized and characterized by elemental analysis, ultraviolet visible (UV–Vis) spectrum, and fourier transform infrared spectroscopy (FTIR). The single-crystal X-ray diffraction structure analysis of the complex revealed that the copper atom was octahedrally coordinated. The catalytic potential of this complex was examined by the oxidation reaction of various aromatic substrates, such as styrene, ethyl benzene, α-methyl styrene, and benzyl alcohol. The oxidation reactions were carried out in acetonitrile with H2O2 and catalytic amounts of [LCuCl2(H2O)] at 70 °C. The catalyst exhibited good catalytic activity in the oxidation of benzyl alcohol (97.50% conv. in 1 h; TONs = 341.25), α-methyl styrene (97.72% conv. in 4 h; TONs = 342.02) and methyl styrene (99.00% conv. in 8 h; TONs = 346.50). The major products were 96.07% benzoic acid from benzyl alcohol, 93.54% acetophenone from α-methyl styrene and 86.38% benzaldehyde from styrene, respectively. A plausible catalytic mechanism involving an active cation [LCu2+] and an epoxy intermediate was proposed based the results of time-dependent electrospray ionization mass spectrometry (ESI-MS) of the reaction mixture.
- Wu, Chengcheng,Liu, Bin,Geng, Xin,Zhang, Zhenyu,Liu, Shenghua,Hu, Quanyuan
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p. 334 - 341
(2018/11/30)
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- Axial base-controlled catalytic activity, oxidative stability and product selectivity of water-insoluble manganese and iron porphyrins for oxidation of styrenes in water under green conditions
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A series of water-insoluble iron(III) and manganese(III) porphyrins, FeT(2-CH3)PPCl, FeT(4-OCH3)PPCl, FeT(2-Cl)PPCl, FeTPPCl, MnT(2-CH3)PPOAc, MnT(4-OCH3)PPOAc, MnT(2-Cl)PPOAc and MnTPPOAc, in the presence of imidazole (ImH), F?, Cl?, Br? and acetate were used as catalysts for the aqueous-phase heterogeneous oxidation of styrenes to the corresponding epoxides and aldehydes with sodium periodate. Also, the effect of various reaction parameters such as reaction time, molar ratio of catalyst to axial base, type of axial base, molar ratio of olefin to oxidant and nature of metal centre on the activity and oxidative stability of the catalysts and the product selectivity was investigated. Higher catalytic activities were found for the iron complexes. Interestingly, the selectivity towards the formation of epoxide and aldehyde (or acetophenone) was significantly influenced by the type of axial base. Furthermore, Br? and ImH were found to be the most efficient co-catalysts for the oxidation of olefins performed in the presence of the manganese and iron porphyrins, respectively. The optimized molar ratio of catalyst to axial base was different for various axial bases. Also, the order of co-catalyst activity of the axial bases obtained in aqueous medium was different from that reported for organic solvents. The use of a convenient axial base under optimum reaction catalyst to co-catalyst molar ratio in the presence of the manganese porphyrin gave the oxidative products with a conversion of ca 100% in a reaction time of less than 3?h. However, the catalytic activity of the iron porphyrins could not be effectively improved by increasing the catalyst to co-catalyst molar ratio.
- Zakavi, Saeed,Hashemi-Amiri, Akbar,Asadi, Fatemeh
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- "ship in a bottle" Porph@MOMs as highly efficient catalysts for selective controllable oxidation and insights into different mechanisms in heterogeneous and homogeneous environments
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In the present work, three "ship in a bottle" Porph@MOMs are reported as biomimetic oxidation catalysts for different reactions. These frameworks are constructed from trimesic acid and metal ions (M = Fe, Co and Mn) in which tetra(N-methyl-4-pyridyl)porphyrin (MTMPyP) is encapsulated within the cavities. Additionally, the catalytic activities of the corresponding homogeneous compounds, FeTMPyP, CoTMPyP and MnTMPyP, and the frameworks without porphyrins within the cavities were investigated in the foregoing oxidation reactions. The prepared 3D porous structures have the ability to control selectivity toward the desired product. Furthermore, they are capable of acting as effective peroxidase mimics, which successfully catalyze the oxidation of diverse olefins as well as hydrocarbons using TBHP as an oxidant. The heterogeneous catalysts significantly enhance conversion in contrast to their corresponding homogeneous systems. Remarkably, an insight into the catalyst behavior was gained from the proposed mechanism based on the reversal of selectivity. Investigation of the stability and reusability of the catalysts revealed the heterogeneity character of the catalyst with no desorption during the course of oxidation reactions. The high yields, clean reactions, high thermal stability and reusability of the catalysts make them good candidates for heterogeneous catalysts in various oxidation reactions.
- Saghian,Dehghanpour,Sharbatdaran
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p. 12872 - 12881
(2018/08/01)
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- Remarkable increase in the rate of the catalytic epoxidation of electron deficient styrenes through the addition of Sc(OTf)3 to the MnTMTACN catalyst
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The effect of Lewis acids on the catalytic activity of [Mn2(μ-O)3(TMTACN)2](PF6)2 in the epoxidation of styrenes using hydrogen peroxide as the oxidant has shown that the addition of Sc(OTf)3 at low catalytic loading results in a very significant increase in the efficiency of the catalyst and a reduction of the reaction time to only 3 minutes in most cases.
- Nodzewska, Aneta,Watkinson, Michael
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supporting information
p. 1461 - 1464
(2018/02/19)
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- 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane: An efficient and high oxygen content oxidant in various oxidative reactions
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Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times.
- Khosravi, Kaveh,Naserifar, Shirin
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supporting information
p. 6584 - 6592
(2018/10/05)
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- Multicore Artificial Metalloenzymes Derived from Acylated Proteins as Catalysts for the Enantioselective Dihydroxylation and Epoxidation of Styrene Derivatives
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Artificial metalloenzymes (AME′s) are an interesting class of selective catalysts, where the chiral environment of proteins is used as chiral ligand for a catalytic metal. Commonly, the active site of an enzyme is modified with a catalytically active metal. Here we present an approach, where the commercial proteins lysozyme (LYS) and bovine serum albumin (BSA) can be converted into highly active and enantioselective AME′s. This is achieved by acylation of the proteins primary amino groups, which affords the metal salts in the core of the protein. A series of differently acylated LYS and BSA were reacted with K2OsO2(OH)4, RuCl3, and Ti(OMe)4, respectively, and the conjugates were tested for their catalytic activity in dihydroxylation and epoxidation of styrene and its derivatives. The best suited system for dihydroxylation is fully acetylated LYS conjugated with K2OsO2(OH)4, which converts styrene to 1,2-phenylethanediol with an enantioselectivity of 95 % ee (S). BSA fully acylated with hexanoic acid and conjugated with three moles RuCl3 per mole protein shows the highest ee values for the conversion of styrene to the respective epoxide with enenatioselectivities of over 80 % ee (R), a TON of more than 2500 and a yield of up to 78 % within 24 h at 40 °C. LYS has two favored selective binding sites for the metal catalyst and BSA has even three. The AME′s with titanate in the active center invert the enantioselectivity of styrene epoxidation.
- Leurs, Melanie,Dorn, Bjoern,Wilhelm, Sascha,Manisegaran, Magiliny,Tiller, Joerg. C.
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p. 10859 - 10867
(2018/08/03)
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- Enantioselective, Lewis Base-Catalyzed Carbosulfenylation of Alkenylboronates by 1,2-Boronate Migration
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A catalytic, enantioselective method for the preparation of chiral, non-racemic, alkylboronic esters bearing two vicinal stereogenic centers is described. The reaction proceeds via a 1,2-migration of a zwitterionic thiiranium-boronate complex to give excl
- Tao, Zhonglin,Robb, Kevin A.,Panger, Jesse L.,Denmark, Scott E.
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p. 15621 - 15625
(2018/11/23)
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- Manganes-Porphyrin as Efficient Enantioselective Catalyst for Aerobic Epoxidation of Olefins
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A chiral manganese porphyrin, [Mn(TCPP-Ind)Cl], was synthesized using cis-1-amino-2-indanol substituent. It showed remarkable catalytic activity and enantioselectivity in the epoxidation of olefins with O2/RCHO. Terminal olefins and styrene derivatives were successfully oxidized (> 99% ee). TON of 73,000 was achieved in the epoxidation of α-methylstyrene after five times recycling. Graphical Abstract: [Figure not available: see fulltext.].
- Farokhi, Afsaneh,Berijani, Kayhaneh,Hosseini-Monfared, Hassan
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p. 2608 - 2618
(2018/06/14)
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- Collaborative effect of Mn-porphyrin and mesoporous SBA-15 in the enantioselective epoxidation of olefins with oxygen
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The rational design of heterogeneous, low cost transition metal complexes that can catalyze olefin with high enantioselectivity and activity has been a challenging goal for the synthetic chemist. In this study a chiral ion pair strategy was used for the synthesis of a biomimetic efficient manganese-tetrapyridylporphyrin (H2TPyP) catalyst for the asymmetric epoxidation of olefins with O2. Complex Mn-TPyP was covalently linked to mesoporous SBA-15 in heme-type environments and its counter ion was replaced by L-tartrate anion (SBA15-[Mn(TPyP)TA]). Chiral and achiral homogeneous analogous of Mn-TPyP were also prepared. The Mn-porphyrin confined in nanoreactors of SBA-15 exhibited enhanced activity (TOF = 652 h?1) and enantiomeric excess (ee 93%) compared with the value obtained when the same chiral catalyst functioned in homogeneous solution (TOF 97 h?1 and ee 83%) in the oxidation of 1-decene with O2/isobutyraldehyde. The high specific surface area, uniformly sized pore channels and site isolated active centers of the catalyst may contribute to the high activity and enantioselectivity. SBA15-[Mn(TPyP)TA] was structurally stable and could be recycled for repeated use. Total turnover number in the oxidation of styrene after five cycles was 47,400 with 86% epoxide selectivity and ee 86%.
- Berijani, Kayhaneh,Hosseini-Monfared, Hassan
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p. 113 - 120
(2017/11/10)
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- Enhanced Turnover for the P450 119 Peroxygenase-Catalyzed Asymmetric Epoxidation of Styrenes by Random Mutagenesis
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A randomized library is constructed based on pET30a-CYP119-T214V plasmid. This library of random mutants of CYP119-T214V was screened by means of the reduced CO difference spectra and epoxidation of styrene. By using directed evolution, a new CYP119 quadr
- Wang, Li,Wei, Siping,Pan, Xianchao,Liu, Pingxian,Du, Xi,Zhang, Chun,Pu, Lin,Wang, Qin
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p. 2741 - 2749
(2018/02/28)
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- Enhanced enantioselective oxidation of olefins catalyzed by Mn-porphyrin immobilized on graphene oxide
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An efficient enantioselective heterogeneous catalyst, GO-[Mn(TPyP)tart], was prepared by covalent attachment of Mn(III) complex of H2TPyP via the propyl linkage to graphene oxide (GO) nanosheet and using chiral tartrate counter ion. The catalyst was characterized by Fourier transform infrared (FT-IR), diffuse reflectance ultraviolet–visible (DR UV–Vis) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman and thermogravimetric analysis (TGA). The graphene-supported Mn-porphyrin showed higher activity for the enantioselective epoxidation of unfunctionalized olefins with molecular oxygen in the presence of isobutyraldehyde. It could be recovered easily and reused in asymmetric oxidation of styrene precursor in a five-step sequence without any considerable loss of its catalytic activity and selectivity. The obtained optically epoxide selectivities were achieved in 86% to 100%.
- Berijani, Kayhaneh,Farokhi, Afsaneh,Hosseini-Monfared, Hassan,Janiak, Christoph
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p. 2202 - 2210
(2018/04/02)
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- Cu-Schiff base complex grafted onto graphene oxide nanocomposite: Synthesis, crystal structure, electrochemical properties and catalytic activity in oxidation of olefins
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Copper(II) Schiff base complex has been immobilized onto graphene oxide (GO) via covalent bonding. The nanocomposite was characterized using powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and UV–visible spectroscopies, transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA) and the energy-dispersive X-ray spectroscopy (EDX). The amount of catalyst loading on the solid support was determined by atomic absorption spectroscopy. The thermogravimetric analysis (TGA) demonstrated that the nanocatalyst was stable up to almost 220?°C, exhibiting high thermostability. Highly active and selective catalyst was found with excellent turnover numbers (up to 47,000 for oxidation of styrene) for the epoxidation of olefins in ethanol using aqueous hydrogen peroxide as oxidant. It could be readily reused for successive ten times without discernible activity and selectivity deterioration, which displays potential for practical applications.
- Rayati, Saeed,Khodaei, Elham,Shokoohi, Saeedeh,Jafarian, Majid,Elmi, Bahareh,Wojtczak, Andrzej
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p. 520 - 528
(2017/07/22)
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- Dioxidovanadium(V) complexes containing thiazol-hydrazone NNN-donor ligands and their catalytic activity in the oxidation of olefins
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The reaction between tridentate NNN donor ligands, (E)-2-(2-(pyridin-2-ylmethylene)hydrazinyl)benzo[d]thiazole (HL1) and (E)-2-(2-(phenyl(pyridin-2-yl)methylene)hydrazinyl)benzo[d]thiazole (HL2), with VO(acac)2in ethanol gave [VO2(L1)] (1) and [VO2(L2)] (2) complexes. Complex [VO2(L2)]·0.2(H2O) (3) was produced from the reaction of HL2and V2O5in ethanol. Molecular structures of complexes were determined by single-crystal X-ray diffraction. All of the investigated compounds were further characterized by elemental analysis, FT-IR, UV–vis and NMR spectroscopy. The dioxidovanadium(V) species were used as catalysts for olefin oxidation in the presence of hydrogen peroxide (H2O2) as an oxidant. Under similar experimental conditions with equal vanadium loading, the presence of the [VO2(L1)] (1) resulted in higher conversion than in the case of using [VO2(L2)] (2) and [VO2(L2)]·0.2(H2O) (3) as catalytic agents.
- Ghorbanloo, Massomeh,Jafari, Solmaz,Bikas, Rahman,Krawczyk, Marta S.,Lis, Tadeusz
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