- Microencapsulated VO(acac)2: Preparation and Use in Allylic Alcohol Epoxidation
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(matrix presented) Microencapsulated VO(acac)2 [MC-VO(acac)2] has been prepared and screened with success as a catalyst for the epoxidation of allylic alcohols using tert-butyl hydroperoxide as oxidant. The reactions are run in hexane at room temperature. The MC-VO(acac)2 is reusable without significant loss of activity.
- Lattanzi, Alessandra,Leadbeater, Nicholas E.
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- Click functionalization of magnetite nanoparticles: A new magnetically recoverable catalyst for the selective epoxidation of olefins
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A new magnetically recoverable heterogeneous molybdenum catalyst was developed by means of a click chemistry approach. First, silica-coated magnetite nanoparticles were functionalized using a bidentate ligand via thiol–ene click reaction of mercaptopropyl-modified magnetite nanoparticles with acrylic acid. Then, a molybdenum complex was covalently supported on the surface of the clicked silica-coated magnetite nanoparticles. The prepared catalyst was characterized using Fourier transform infrared and inductively coupled plasma optical emission spectroscopies, X-ray diffraction, vibrating sample magnetometry and transmission electron microscopy. The catalytic performance of the prepared heterogeneous catalyst was investigated in the epoxidation of olefins with tert-butyl hydroperoxide as oxidant. This catalyst could be reused for five runs without significant loss of activity and selectivity.
- Masteri-Farahani, Majid,Shahsavarifar, Samaneh
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- Surface modification of magnetite nanoparticles with molybdenum-dithiocarbamate complex: a new magnetically separable nanocatalyst
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Surface modification of silica-coated magnetite nanoparticles (SCMNPs) by anchoring of molybdenum-dithiocarbamate complex resulted in the preparation of a new magnetically separable nanocatalyst for the epoxidation of olefins. The prepared nanocatalyst was characterized by various physicochemical techniques which indicated that the molybdenum complex is successfully supported on the SCMNPs support. This heterogeneous catalyst exhibited good catalytic activity and high selectivity in the epoxidation of olefins with tert-butyl hydroperoxide as oxidant under mild reaction conditions. It can be easily recovered by an external magnetic field and reused up to three times without noticeable deactivation. Graphical abstract: [Figure not available: see fulltext.].
- Masteri-Farahani, Majid,Modarres, Maryam
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- Organocatalyzed Domino [3+2] Cycloaddition/Payne-Type Rearrangement using Carbon Dioxide and Epoxy Alcohols
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An unprecedented organocatalytic approach towards highly substituted cyclic carbonates from tri- and tetrasubstituted oxiranes and carbon dioxide has been developed. The protocol involves the use of a simple and cheap superbase under mild, additive- and metal-free conditions towards the initial formation of a less substituted carbonate product that equilibrates to a tri- or even tetrasubstituted cyclic carbonate under thermodynamic control. The latter are conveniently trapped in situ, providing overall a new domino process for synthetically elusive heterocyclic scaffolds. Control experiments provide a rationale for the observed cascade reactions, which demonstrate similarity to the well-known Payne rearrangement of epoxy alcohols.
- Sope?a, Sergio,Cozzolino, Mariachiara,Maquilón, Cristina,Escudero-Adán, Eduardo C.,Martínez Belmonte, Marta,Kleij, Arjan W.
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- Rational Design of a Polyoxometalate Intercalated Layered Double Hydroxide: Highly Efficient Catalytic Epoxidation of Allylic Alcohols under Mild and Solvent-Free Conditions
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Intercalation catalysts, owing to their modular and accessible gallery and unique interlamellar chemical environment, have shown wide application in various catalytic reactions. However, the poor mass transfer between the active components of the intercalated catalysts and organic substrates is one of the challenges that limit their further application. Herein, we have developed a novel heterogeneous catalyst by intercalating the polyoxometalate (POM) of Na9LaW10O36?32 H2O (LaW10) into layered double hydroxides (LDHs), which have been covalently modified with ionic liquids (ILs). The intercalation catalyst demonstrates high activity and selectivity for the epoxidation of various allylic alcohols in the presence of H2O2. For example, trans-2-hexen-1-ol undergoes up to 96 % conversion and 99 % epoxide selectivity at 25 °C in 2.5 h. To the best of our knowledge, the Mg3Al?ILs?C8?LaW10composite material constitutes one of the most efficient heterogeneous catalysts for the epoxidation of allylic alcohols (including the hydrophobic allylic alcohols with long alkyl chains) reported so far.
- Li, Tengfei,Wang, Zelin,Chen, Wei,Miras, Haralampos N.,Song, Yu-Fei
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- Immobilized molybdenum-thiosemicarbazide Schiff base complex on the surface of magnetite nanoparticles as a new nanocatalyst for the epoxidation of olefins
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In this work, a new magnetically recoverable nanocatalyst was developed by immobilization of thiosemicarbazide ligand on the surface of silica coated magnetite nanoparticles (SCMNPs) through Schiff base condensation and followed complexation with MoO2(acac)2. Characterization of the prepared nanocatalyst was performed with different physicochemical methods such as Fourier transform infrared (FT-IR) and atomic absorption spectroscopies, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The prepared catalyst catalyzed the epoxidation of olefins and allyl alcohols with tert-butyl hydroperoxide (TBHP) and cumene hydroperoxide (CHP) quantitatively with excellent selectivity toward the corresponding epoxides under mild reaction conditions.
- Mohammadikish,Masteri-Farahani,Mahdavi
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- Oxidation of geraniol and other substituted olefins with hydrogen peroxide using mesoporous, sol-gel-made tungsten oxide-silica mixed oxide catalysts
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The preparation of a series of mesoporous tungsten oxide-silica mixed oxides by sol-gel methods under basic conditions is reported. Surface modification with methyl and 3-chloropropyl groups is possible in an amount between 10 and 40 mol% with respect to the silane precursor. The amount of polar organic functional groups controls the surface area, the porosity, and the catalytic activity of the solids in the oxidation of different substrates with hydrogen peroxide. The oxidation of geraniol is studied in detail. The catalysts are active and produce epoxides in good yields. The latter are influenced by the presence of polar organic groups. The preparation method allows the preparation of catalysts that are resistant to leaching and can be recycled several times without appreciable loss of activity.
- Somma, Filippo,Strukul, Giorgio
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- Olefin epoxidation with ionic liquid catalysts formed by supramolecular interactions
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This work demonstrated that the specific ionic liquids (ILs) have been designed via the supramolecular complexation between 18-crown-6 (CE) and ammonium peroxoniobate (NH4-Nb). The resultant ILs have been characterized by elemental analysis, FT-IR, Raman, NMR, DSC, conductivity measurement and MALDI-TOF, etc. The IL (CE-1) consisting of CE and ammonium peroxoniobate can be further coordinated with GLY to generate a new IL (CE-2), which showed both high catalytic activity in epoxidation with H2O2 and good recyclability. The characterization of 93Nb NMR spectra revealed that the peroxoniobate anions has demonstrated a structural evolution in the presence of hydrogen peroxide, in which Nb[dbnd]O species can be easily oxidized into the catalytically active niobium?peroxo species. Especially, the supramolecular complexation can provide suitable hydrophobicity, which ensured that the hydrophobic olefins and allylic alcohols were easily accessible to the catalytically active anions, and thus facilitated the epoxidation reaction. Notably, the supramolecular IL catalysts in this work exhibited a huge advantage of the easy availability, as compared with the previously reported peroxoniobate-based ILs. As far as we know, this is the first example of the highly selective epoxidation of olefins and allylic alcohols by using supramolecular ILs as catalysts.
- Ding, Bingjie,Hou, Zhenshan,Li, Difan,Ma, Wenbao,Yao, Yefeng,Zhang, Ran,Zheng, Anna,Zhou, Qingqing
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- Synthesis, characterization and immobilization of a novel mononuclear vanadium (V) complex on modified magnetic nanoparticles as catalyst for epoxidation of allyl alcohols
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The 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) undergoes hydrolysis in the presence of VO(SO4) in an alkaline solution, affording mainly the bis(2-pyridyl carbonyl)amid) VO2 complex, designated as [VO2(bpca)]. Single-crystal X-ray crystallography revealed that the coordination of V in complex is a distorted square-pyramid coordinated with three nitrogen of bis(2-pyridyl carbonyl)amid) ligand and two binding oxygen atoms. The prepared complex which successfully supported on modified Fe3O4 nanoparticles using tetraethylorthosilicate (TEOS) and (3-aminopropyl)trimethoxysilane(APTMS)was designated as Fe3O4@SiO2@APTMS@[VO2(bpca)] complex (nanocatalyst). The complex and nanocatalyst were characterized by means of FT-IR, XRD, VSM, SEM and TEM. The catalytic activity of [VO2(bpca)] complex and Fe3O4@SiO2@APTMS@complex as catalysts 1 and 2 were evaluated by the epoxidation of geraniol, 3-methyl-2-buten-1-ol, trans-2-hexen-1-ol and 1-octen-3-ol with 70–98% conversions and 95–100% selectivities. Based on the obtained results, the heterogeneity and reusability of the catalyst seems promising. In addition, the in vitro antibacterial activity of [VO2 (bpca)] complex have also been evaluated and compared to the activities of other vanadium complexes, tptz ligand and two standard antibacterial drugs, Nalidixic acid and Vancomycin.
- Azarkamanzad, Zahra,Farzaneh, Faezeh,Maghami, Mahboobeh,Simpson, Jim,Azarkish, Mohammad
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- A Ni-containing decaniobate incorporating organic ligands: Synthesis, structure, and catalysis for allylic alcohol epoxidation
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An organic-inorganic hybrid polyoxoniobate, Na8{Ni[Ni(en)]2Nb10O32}·28H2O (1) (en = ethanediamine), has been synthesized and characterized. It represents the first example of a trinuclear nickel-containing polyoxoniobate. The catalysis of 1 for allylic alcohol epoxidation was investigated at room temperature in aqueous solution, and was found to catalyze the epoxidation of 3-methyl-2-buten-1-ol with high conversion (98%) and selectivity (94%). Furthermore, magnetic measurements showed that the compound exhibits ferromagnetic interactions.
- Li, Li,Niu, Yanjun,Dong, Kaili,Ma, Pengtao,Zhang, Chao,Niu, Jingyang,Wang, Jingping
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- A new magnetically recoverable nanocatalyst for epoxidation of olefins
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In this work, a new magnetically recoverable nanocatalyst was developed by covalent binding of a Schiff base ligand, N,N′-bis(3- salicylidenaminopropyl)amine (salpr), on the surface of silica coated magnetite nanoparticles (SCMNPs) and followed complexation with MoO2(acac) 2. Characterization of the prepared nanocatalyst was performed with different physicochemical methods such as FT-IR and atomic absorption spectroscopies, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). Finally, catalytic activity of the prepared MoO2salpr/SCMNPs was examined in the epoxidation of olefins with tert-butyl hydroperoxide (TBHP) and cumene hydroperoxide (CHP).
- Masteri-Farahani,Tayyebi
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- Total Synthesis of (-)-Nemorosone and (+)-Secohyperforin
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A general strategy for the synthesis of polycyclic polyprenylated acylphloroglucinols is described in which a scalable, Lewis acid catalyzed epoxide-opening cascade cyclization is used to furnish common intermediate 4. The utility of this approach is exemplified by the total syntheses of both ent-nemorosone and (+)-secohyperforin, which were each accomplished in four steps from this intermediate.
- Sparling, Brian A.,Tucker, James K.,Moebius, David C.,Shair, Matthew D.
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- Molybdenum complex tethered to the surface of activated carbon as a new recoverable catalyst for the epoxidation of olefins
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A new recoverable catalyst for the epoxidation of olefins was developed by covalent attachment of aminopropyl groups on the surface of oxidized activated carbon (AC) and next reaction with bis(acetylacetonato)dioxomolybdenum(VI). Characterization of the prepared catalyst was performed with different physicochemical methods such as Fourier transform infrared and atomic absorption spectroscopies, scanning electron microscopy, energy-dispersive X-ray and nitrogen sorption analyses. Nitrogen adsorption-desorption analysis revealed that the textural characteristics of the support were changed during the grafting experiments but the channels remained relatively accessible despite sequential reduction in surface area, pore volume and pore size. Elemental analysis showed the presence of 0.06 mmol g-1 molybdenum in the catalyst. The prepared catalyst catalyzed the epoxidation of olefins and allyl alcohols with tert-butyl hydroperoxide (TBHP) and cumene hydroperoxide (CHP) quantitatively with excellent selectivity toward the corresponding epoxides under mild reaction conditions. The results indicated that the hydrophobicity of the AC support promoted the catalytic efficiency of the catalyst in the epoxidation of olefins.
- Masteri-Farahani,Abednatanzi
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- Oxidovanadium(V) Anchored to Silanol-Functionalized Polyoxotungstates: Molecular Models for Single-Site Silica-Supported Vanadium Catalysts
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The metalation of two different types of silanol-decorated polyoxotungstates, [XW9O34-x(tBuSiOH)3]3- (X = P, x = 0; X = Sb, x = 1) and [PW10O36(tBuSiOH)2]3-, by Cl3VO or (iPrO)3VO has been achieved. The characterization of the resulting oxidovanadium(V) complexes [XW9O34-x(tBuSiO)3VO]3- (X = P, 3; X = Sb, 3′) and [PW10O36(tBuSiO)2VO(iPrO)]3- (4) has been fully detailed, including X-ray analysis. These compounds are present in monomeric forms and therefore represent original molecular models for tris-grafted and bis-grafted isolated (V=O)3+ species dispersed onto silica. Their ability as precatalysts for the epoxidation of cyclic olefins and allylic alcohols with tert-butyl hydroperoxide (TBHP) has been studied. The results suggested that a confined tris-grafted species, such as 3 or 3′, does not act as an efficient catalyst whereas a more labile bis-grafted species, such as 4, does. To gain a better understanding, we have assessed their suitability for ligand exchange with alcohols and TBHP and performed reaction progress kinetic analysis by monitoring the epoxidation of 3-methyl-2-buten-1-ol by 1H and 51V nuclear magnetic resonance.
- Guillemot, Geoffroy,Matricardi, Edoardo,Chamoreau, Lise-Marie,Thouvenot, René,Proust, Anna
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- Polyoxotungstates incorporated organophosphonate and nickel: Synthesis, characterization and efficient catalysis for epoxidation of allylic alcohols
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Three new sandwich-type organophosphonate-functionalized polyoxotungstate clusters, [{Ni(H2O)5}x(AsW6O21)2{Ni(OOCCH2NCH2PO3)2}3] (x = 0 (Ni1), 1 (Ni2 and Ni3)), were successfully isolated via a "top-down" synthetic strategy. Compounds (Ni1-Ni3) were characterized by single crystal X-ray analysis, X-ray powder diffraction (XRPD), IR spectroscopy, UV-vis spectroscopy, and thermogravimetric analyses (TGA). Magnetic properties provide evidence for antiferromagnetic coupling in Ni2 and Ni3 and ferromagnetic interaction in Ni1. Catalytic studies of the three polyoxotungstates for the oxidation of allylic alcohols to epoxides have been investigated in water with H2O2 as the oxidant. All three polyoxotungstates exhibit efficient catalytic performance with excellent conversion and high selectivity at room temperature.
- Xu, Qiaofei,Li, Yingguang,Ban, Ran,Li, Zhao,Han, Xiao,Ma, Pengtao,Singh, Vikram,Wang, Jingping,Niu, Jingyang
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- Epoxidation of allylic alcohols on self-assembled polyoxometalates hosted in layered double hydroxides with aqueous H2O2 as oxidant
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A series of self-assembled polyoxometalate (POM) catalysts were directly immobilized into layered double hydroxides (LDH) by a selective ion-exchange method. Sandwich-type POM species are found to be more favorable than Keggin-type POM for the direct immobilization in LDH, because strict pH controlling is not needed and the LDH hosts can be kept intact. The resulting LDH-POM catalysts were evaluated in the epoxidation of allylic alcohols with aqueous H2O2 as the oxidant without using organic solvent. The heterogeneous LDH-POM catalysts show much higher epoxide selectivity than the corresponding homogeneous Na-POM catalysts, which can be attributed to the beneficial effect of basic LDH host on the suppression of the acid-catalyzed epoxide hydrolysis. The cooperation between the POM guest and the LDH host can achieve up to 99% selectivity of epoxide, 95% H2O2 efficiency and 37200 h-1 TOF without the need of base additives and pH controlling, and the host-guest catalysts can be readily recycled with no apparent loss of catalytic performance.
- Liu, Peng,Wang, Changhao,Li, Can
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- One-pot, facile synthesis and fast separation of a UiO-66 composite by a metalloporphyrin using nanomagnetic materials for oxidation of olefins and allylic alcohols
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One-pot facile synthesis of a new composite based on the incorporation of a metalloporphyrin within the UiO-66 metal-organic framework is reported. To enhance the catalytic activity of UiO-66, pore modification with (CoTHPP(OAC) = meso-tetrakis(4-hydroxyp
- Abbasi, Alireza,Masteri-Farahani, Majid,Rayati, Saeed,Zamani, Samira
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p. 654 - 662
(2022/01/22)
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- Role of Organic Fluoride Salts in Stabilizing Niobium Oxo-Clusters Catalyzing Epoxidation
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We present here that easily available organic salts can stabilize/modify niobium (Nb) oxo-clusters. The as-synthesized Nb oxo-clusters have been characterized by various methods. These Nb oxo-clusters were catalytically active for the epoxidation of allylic alcohols and olefins with H2O2 as an oxidant. Notably, Nb-OC@TBAF-0.5 appeared as highly dispersed nanosized particles and showed the highest catalytic activity, which can be attributed to the following reasons on the basis of characterization. First, the strong coordination of fluorine ions with Nb sites and the steric protection with bulky organic cations led to high stabilization and dispersion of the oxo-clusters in the course of the reaction. Second, a hydrogen-bond interaction between the coordinated fluorine atom and the -OH group of allylic alcohol favored the epoxidation reaction. Third, the electron density of Nb sites decreased due to the strong electron-withdrawing ability of F- adjacent to Nb sites, thus promoting the electrophilic oxygen transfer to the CC bond.
- Dai, Sheng,Ding, Bingjie,Gong, Xueqing,Hou, Zhenshan,Li, Difan,Tang, Xuan,Xu, Beibei,Yao, Yefeng,Zhang, Tong,Zheng, Anna,Zhou, Qingqing
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p. 8190 - 8203
(2021/07/26)
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- ADENOSINE RECEPTOR BINDING COMPOUNDS
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The present invention relates to pharmaceutical compounds and compositions of Formula (I) and methods of treatment using the compounds and compositions, especially for the treatment and/or prevention of a proliferation disorder, such as cancer. Compounds of Formula (I) as further described herein are shown modulators of the adenosine A2A receptor and exhibit antiproliferative activity. Accordingly, these compounds are useful to treat proliferative disorders such as cancer, and other adenosine receptor-related conditions including an inflammatory disease, renal disease, diabetes, vascular disease, lung disease, or an autoimmune disease.
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Paragraph 00414
(2020/02/06)
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- Three- and two-site heteropolyoxotungstate anions as catalysts for the epoxidation of allylic alcohols by H2O2 under biphasic conditions: Reactivity and kinetic studies of the [Ni3(OH2)3(B-PW9O34){WO5(H2O)}]7?, [Co3(OH2)6(A-PW9O34)2]12?, and [M4(OH2)2(B-PW9O34)2]10? anions, where M?=?Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)
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The trimetallic phosphopolyoxotungstate anions [Ni3(OH2)3(B-PW9O34){WO5(H2O)}]7? and [Co3(OH2)6(A-PW9O34)2]12? have been studied as epoxidation catalysts for oxygen transfer from 30% H2O2 to a range of allylic alcohols under biphasic conditions (1,2-dichloroethane/H2O) at 15 °C. The reaction mechanism involves coordination of an allylic alcohol at an M(II) site in each case, prior to transfer of a peroxy oxygen from an adjacent W(O2) site. The latter is formed from a terminal W = O unit by reaction with H2O2. Evidence of W(O2) formation was obtained through IR studies. The W(O2) group forms the epoxide by transfer of an oxygen atom to the C[dbnd]C bond of the coordinated allylic alcohol. Kinetic studies using 3-methyl-2-buten-1-ol as the allylic alcohol substrate have been modelled with all three metal sites catalytically active. The reaction involves an autocatalysis mechanism involving an induction period, which can be rationalised by proposing not only coordination of the allylic alcohol to M(II), but also the product hydroxy epoxide, both through their –OH groups. The autocatalysis is generated by formation of the W(O2) group adjacent to a coordinated hydroxy epoxide, which competes with coordination of allylic alcohol. The mechanism requires some twenty-one steps involving just the generic steps listed above, with all three metal sites catalytically active. Temperature-dependent kinetic studies and subsequent Eyring analyses have shown that the Co(II)-containing catalyst is the most active of the two. Analogous studies of the epoxidation of 3-methyl-2-buten-1-ol by the two-site [M4(OH2)2(B-PW9O34)2]10? ions as catalysts, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II), at 15 °C gave an order of reactivity of Cu(II) > Ni(II) > Zn(II), Co(II), Mn(II), which mostly mimics the natural order of stability constants (the Irving-Williams series), suggesting that the formation of the allylic alcohol complexes play a dominant role in this series of related complex anions, with greater replacement of water by allylic alcohol leading to greater reactivity.
- Abram, Paulus Hengky,Burns, Robert C.,Li, Lichun
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supporting information
(2019/10/19)
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- Ionic Liquid Stabilized Niobium Oxoclusters Catalyzing Oxidation of Sulfides with Exceptional Activity
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We present here a new class of niobium oxoclusters that are stabilized effectively by carboxylate ionic liquids. These functionalized ILs are designated as [TBA][LA], [TBA][PA], and [TBA][HPA] in this work, in which TBA represents tetrabutylammonium and LA, PA, and HPA refer to lactate, propionate, 3-hydroxypropionate anions, respectively. The as-synthesized Nb oxoclusters have been characterized by use of elemental analysis, NMR, IR, XRD, TGA, HRTEM. It was found that [TBA][LA]-stabilized Nb oxoclusters (Nb?OC@[TBA][LA]) are uniformly dispersed with an average particle size of 2–3 nm and afforded exceptionally high catalytic activity for the selective oxidation of various thioethers. The turnover number with Nb?OC@[TBA][LA] catalyst was over 56 000 at catalyst loading as low as 0.0033 mol % (1 ppm). Meantime, the catalyst also showed the high activity for the epoxidation of olefins and allylic alcohols by using only 0.065 mol % of catalyst (50 ppm). The characterization of 93Nb NMR spectra revealed that the Nb oxoclusters underwent structural transformation in the presence of H2O2 but regenerated to their initial state at the end of the reaction. In particular, the highly dispersed Nb oxoclusters can absorb a large amount of polar organic solvents and thus were swollen greatly, which exhibited “pseudo” liquid phase behavior, and enabled the substrate molecules to be highly accessible to the catalytic center of Nb oxocluster units.
- Zhou, Qingqing,Ye, Man,Ma, Wenbao,Li, Difan,Ding, Bingjie,Chen, Manyu,Yao, Yefeng,Gong, Xueqing,Hou, Zhenshan
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p. 4206 - 4217
(2019/03/26)
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- A mononuclear tantalum catalyst with a peroxocarbonate ligand for olefin epoxidation in compressed CO2
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A new class of tantalum-based peroxocarbonate ionic liquid ([P4,4,4,4]3[Ta(η2-O2)3(CO4)]) has been generated through the reaction of pressurized CO2 with [P4,4,4,4]3[Ta(O)3(η2-O2)] in the presence of H2O2 during the reaction process. The newly formed species has been verified by NMR, FT-IR, HRMS and density functional theory (DFT) calculations. The CO2-induced monomeric peroxocarbonate anion-based ionic liquid is more advantageous than the monomeric peroxotantalate analogue for the epoxidation of olefins under very mild conditions. Interestingly, the transformation between peroxotantalate and peroxocarbonate species is completely reversible, and CO2 can actually act as a trigger agent for epoxidation reaction. The further mechanism studies by DFT calculation reveal that peroxo η2-O2 (site a) affords higher reactivity towards the CC bond than that of peroxocarbonate-CO4 (site b). These quantitative illustrations of the relationship between structural properties and kinetic consequences enable rational design for an efficient and environmental IL catalyst for the epoxidation of olefins.
- Ma, Wenbao,Qiao, Yunxiang,Theyssen, Nils,Zhou, Qingqing,Li, Difan,Ding, Bingjie,Wang, Dongqi,Hou, Zhenshan
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p. 1621 - 1630
(2019/04/10)
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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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- Unveiling the Active Surface Sites in Heterogeneous Titanium-Based Silicalite Epoxidation Catalysts: Input of Silanol-Functionalized Polyoxotungstates as Soluble Analogues
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We report on a site-isolated model for Ti(IV) by reacting [Ti(iPrO)4] with the silanol-functionalized polyoxotungstates [XW9O34-x(tBuSiOH)3]3- (X = P, x = 0, 1; X = Sb, x = 1, 2) in tetrahydrofuran. The resulting titanium(IV) complexes [XW9O34-x(tBuSiO)3Ti(OiPr)]3- (X = P, 3; X = Sb, 4) were obtained in monomeric forms both in solution and in the solid state, as proved by diffusion NMR experiments and by X-ray crystallographic analysis. Anions 3 and 4 represent relevant soluble models for heterogeneous titanium silicalite epoxidation catalysts. The POM scaffolds feature slight conformational differences that influence the chemical behavior of 3 and 4 as demonstrated by their reaction with H2O. In the case of 3, the hydrolysis reaction of the isopropoxide ligand is only little shifted toward the formation of a monomeric [PW9O34(tBuSiO)3Ti(OH)]3- (5) species [log K = -1.96], whereas 4 reacted readily with H2O to form a μ-oxo bridged dimer {[SbW9O33(tBuSiO)3Ti]2O}6- (6). The more confined was the coordination site, the more hydrophobic was the metal complex. By studying the reaction of 3 and 4 with hydrogen peroxide using NMR and Raman spectroscopies, we concluded that the reaction leads to the formation of a titanium-hydroperoxide Ti-(η1-OOH) moiety, which is directly involved in the epoxidation of the allylic alcohol 3-methyl-2-buten-1-ol. The combined use of both spectroscopies also led to understanding that a shift of the acid-base equilibrium toward the formation of Ti(η2-O2) and H3O+ correlates with the partial hydrolysis of the phosphotungstate scaffold in 3. In that case, the release of protons also catalyzed the oxirane opening of the in situ formed epoxide, leading to an increased selectivity for 1,2,3-butane-triol. In the case of the more stable [SbW9O33(tBuSiO)3Ti(OiPr)]3- (4), the evolution to Ti(η2-O2) peroxide was not detected by Raman spectroscopy, and we performed reaction progress kinetic analysis by NMR monitoring the 3-methyl-2-buten-1-ol epoxidation to assess the efficiency and integrity of 4 as precatalyst.
- Zhang, Teng,Mazaud, Louis,Chamoreau, Lise-Marie,Paris, Céline,Proust, Anna,Guillemot, Geoffroy
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p. 2330 - 2342
(2018/03/13)
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- Peroxotantalate-Based Ionic Liquid Catalyzed Epoxidation of Allylic Alcohols with Hydrogen Peroxide
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The efficient and environmentally benign epoxidation of allylic alcohols has been attained by using new kinds of monomeric peroxotantalate anion-functionalized ionic liquids (ILs=[P4,4,4,n]3[Ta(O)3(η-O2)], P4,4,4,n=quaternary phosphonium cation, n=4, 8, and 14), which have been developed and their structures determined accordingly. This work revealed the parent anions of the ILs underwent structural transformation in the presence of H2O2. The formed active species exhibited excellent catalytic activity, with a turnover frequency for [P4,4,4,4]3[Ta(O)3(η-O2)] of up to 285 h?1, and satisfactory recyclability in the epoxidation of various allylic alcohols under very mild conditions by using only one equivalent of hydrogen peroxide as an oxidant. NMR studies showed the reaction was facilitated through a hydrogen-bonding mechanism, in which the peroxo group (O–O) of the peroxotantalate anion served as the hydrogen-bond acceptor and hydroxyl group in the allylic alcohols served as the hydrogen-bond donor. This work demonstrates that simple monomeric peroxotantalates can catalyze epoxidation of allylic alcohols efficiently.
- Ma, Wenbao,Chen, Chen,Kong, Kang,Dong, Qifeng,Li, Kun,Yuan, Mingming,Li, Difan,Hou, Zhenshan
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p. 7287 - 7296
(2017/05/31)
-
- Aerobic Stereoselective Oxidation of Olefins on a Visible-Light-Irradiated Titanium Dioxide-Cobalt-Ascorbic Acid Nanohybrid
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A visible-light-driven photocatalytically active nanocrystalline TiO2 was prepared by surface modification with a cobalt-ascorbic acid complex. The photocatalyst exhibited high activity and excellent chemo-, diastereo-, and stereoselectivities
- Jafarpour, Maasoumeh,Feizpour, Fahimeh,Rezaeifard, Abdolreza
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supporting information
p. 235 - 238
(2017/01/25)
-
- Highly Efficient Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Peroxoniobate-Based Ionic Liquids
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This work reports new kinds of monomeric peroxoniobate anion functionalized ionic liquids (ILs) designated as [A+][Nb=O(O-O)(OH)2] (A+ = tetrapropylammonium, tetrabutylammonium, or tetrahexylammonium cation), which have been prepared and characterized by elemental analysis, HRMS, NMR, IR, TGA, etc. With hydrogen peroxide as an oxidant, these ILs exhibited excellent catalytic activity and recyclability in the epoxidation of various allylic alcohols under solvent-free and ice bath conditions. Interestingly, subsequent activity tests and catalyst characterization together with first-principles calculations indicated that the parent [Nb=O(O-O)(OH)2]- anion has been oxidized into the anion [Nb(O-O)2(OOH)2]- in the presence of H2O2, which constitutes the real catalytically active species during the reaction; this anion has higher activity in comparison to the analogous peroxotungstate anion. Moreover, the epoxidation process of the substrate (allylic alcohol) catalyzed by [Nb(O-O)2(OOH)2]- was explored at the atomic level by virtue of DFT (density functional theory) calculations, identifying that it is more favorable to occur through a hydrogen bond mechanism, in which the peroxo group of [Nb(O-O)2(OOH)2]- serves as the adsorption site to anchor the substrate OH group by forming a hydrogen bond, while OOH as the active oxygen species attacks the C=C bond in substrates to produce the corresponding epoxide. This is the first example of the highly efficient epoxidation of allylic alcohols using a peroxoniobate anion as a catalyst.
- Chen, Chen,Yuan, Haiyang,Wang, Haifeng,Yao, Yefeng,Ma, Wenbao,Chen, Jizhong,Hou, Zhenshan
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p. 3354 - 3364
(2016/07/06)
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- A reusable catalytic system for sulfide oxidation and epoxidation of allylic alcohols in water catalyzed by poly(dimethyl diallyl) ammonium/polyoxometalate
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An effective catalyst based on a polyoxometalate and a polymer has been developed for the oxidation of sulfides and allylic alcohols under mild conditions in water. The synthetic procedure to form the catalyst and the separation of the products are convenient, and the system is reusable.
- Zhao, Wei,Yang, Chunxia,Cheng, Zhiguo,Zhang, Zhenghui
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supporting information
p. 995 - 998
(2016/02/27)
-
- Enhanced aqueous oxidation activity and durability of simple manganese(III) salen complex axially anchored to maghemite nanoparticles
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Simple Mn-salen complex was anchored coordinatively to γ-Fe2O3 nanoparticles through amine functionality which provide a new magnetically recoverable nanocatalyst with high oxidation activity and stability. Catalyst characterization was performed using FT-IR, UV-Vis, XRD, EDS, TGA and ICP-AES. TEM image revealed a quasi-spherical structure with size smaller than 20 nm for nanocatalyst. A thermal stability up to around 300 °C was verified for prepared nanocatalyst based on thermogravimetric analysis. Finally, the catalytic performance of magnetically recoverable Mn-catalyst was exploited in the green oxidation of different types of functional groups including olefins, alcohols, saturated hydrocarbons and sulfur containing compounds with n-Bu4NHSO5 (TBAOX) in water under heterogeneous conditions. The salen catalyst proved to be reusable for at least eight times and the oxidant's by-product (n-Bu4NHSO4) could also be recycled.
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Farrokhi, Alireza,Parvin, Sousan,Feizpour, Fahimeh
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p. 64640 - 64650
(2016/07/21)
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- A synergistic effect of a cobalt Schiff base complex and TiO2 nanoparticles on aerobic olefin epoxidation
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In this study, a cobalt Schiff base complex and TiO2 nanoparticles exhibited a synergistic effect on the visible-light photocatalytic activity in the aerobic oxidation of various olefins in the absence of a reducing agent. The catalyst structure was found to be well preserved after the oxidation reaction and the catalyst could be reused at least five times.
- Jafarpour, Maasoumeh,Kargar, Hossein,Rezaeifard, Abdolreza
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p. 79085 - 79089
(2016/09/09)
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- Asymmetric epoxidation of α,β-unsaturated aldehydes catalyzed by a spiro-pyrrolidine-derived organocatalyst
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The asymmetric epoxidation of α,β-unsaturated aldehydes, catalyzed by a spiro-pyrrolidine (SPD)-derived organocatalyst, has been accomplished with good diastereoselectivities (up to dr >20:1) and with high to excellent enantioselectivities (up to 99% ee).
- Xu, Ming-Hui,Tu, Yong-Qiang,Tian, Jin-Miao,Zhang, Fu-Min,Wang, Shao-Hua,Zhang, Shi-Heng,Zhang, Xiao-Ming
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p. 294 - 300
(2017/03/01)
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- Post-synthetic modification of nanoporous Cu3(BTC)2 metal-organic framework via immobilization of a molybdenum complex for selective epoxidation
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In the present work, nanoporous Cu3(BTC)2 (abbreviated as CuBTC and BTC = benzene-1,3,5-tricarboxylate) metal-organic framework (MOF) was modified in a two-step post-synthetic reaction by covalent attachment of aminopyridine groups followed by the reaction with bis(acetylacetonato) dioxomolybdenum(VI). The prepared molybdenum containing MOF was utilized as a heterogeneous catalyst in the epoxidation of olefins and allylic alcohols. Characterization of the prepared catalyst was performed using Fourier transform infrared, atomic absorption spectroscopies, CHN elemental analysis, powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and nitrogen adsorption/desorption techniques. The resulting catalyst showed high selectivity and catalytic activity toward the epoxidation reaction. Moreover, the catalyst demonstrated size-selective properties suggested the reaction occurred inside the pores.
- Abednatanzi, Sara,Abbasi, Alireza,Masteri-Farahani, Majid
-
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- Organosulfate and nitrate formation and reactivity from epoxides derived from 2-methyl-3-buten-2-ol
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Recent work has suggested that 2-methyl-3-butene-2-ol (MBO)-derived epoxide intermediates are responsible for some of the molecular species commonly found in ambient secondary organic aerosol (SOA). Nuclear magnetic resonance techniques were used to study the reaction kinetics and products of two potential MBO-derived epoxides under acidic solution conditions in the presence of sulfate and nitrate nucleophiles. These epoxides were found to undergo reasonably fast acid-catalyzed reaction at typical SOA acidities and to produce a variety of organosulfate and nitrate species. This finding supports a previous supposition that 3-methylbutane-1,2,3-triol and at least some of the MBO-derived organosulfates previously detected on SOA are formed from the reactions of these epoxides. In general, the particular MBO-derived organosulfates and nitrates produced from MBO-derived epoxides and their respective stability toward hydrolysis were similar to those found for isoprene-derived epoxides; the nucleophilic reactions were observed to be quite regiospecific, and the tertiary addition product species were found to hydrolyze on atmospherically relevant time scales.
- Mael, Liora E.,Jacobs, Michael I.,Elrod, Matthew J.
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p. 4464 - 4472
(2015/05/27)
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- Enhanced catalytic activity of nanoporous Cu3(BTC)2 metal-organic framework via immobilization of oxodiperoxo molybdenum complex
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Molybdenum(vi) oxodiperoxo complex was immobilized into a post synthetically modified Cu3(BTC)2 metal-organic framework (abbreviated as CuBTC MOF, BTC = benzene-1,3,5-tricarboxylate). Characterization of the modified CuBTC MOF by Fourier transform infrared and atomic absorption spectroscopies as well as thermogravimetric and CHN elemental analyses confirmed successful modification of the framework. Powder X-ray diffraction revealed a shift for all peaks to smaller 2 angles during the molybdenum complex attachment as the result of MOF expansion. Nitrogen adsorption/desorption techniques demonstrated a significant decrease in BET surface area and total pore volume during the modification process. The resulting molybdenum-containing MOF showed higher catalytic activity and selectivity than the CuBTC MOF due to the presence of the molybdenum(vi) oxodiperoxo complex.
- Abednatanzi, Sara,Abbasi, Alireza,Masteri-Farahani, Majid
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p. 5322 - 5328
(2015/07/07)
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- The catalytic efficiency of Fe-porphyrins supported on multi-walled carbon nanotubes in the heterogeneous oxidation of hydrocarbons and sulfides in water
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Novel recoverable biomimetic catalysts were prepared by the coordinative anchoring of an iron(iii) meso-tetraphenyl porphyrin complex [Fe(TPP)Cl] and some derivatives on the activated multi-walled carbon nanotube (AMWCNT) via hydroxyl functionality (Fe-Por-AMWCNT). The simple heterogeneous catalyst [Fe(TPP)Cl-MWCNT] was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman, FT-IR and UV-vis spectroscopy. The amount of catalyst loading on the nanotubes, was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The thermogravimetric analysis (TGA) demonstrated that the nanocatalyst was thermally stable up to almost 400 °C, exhibiting high thermostability. The epoxidation of olefins and the oxidation of saturated hydrocarbons to the related ketones and also sulfides to the sulfones by aqueous solution of tetra-n-butylammonium peroxomonosulfate (n-Bu4NHSO 5, TBAOX) were efficiently enhanced with excellent selectivity under the influence of the separable nanocatalyst with very low catalyst loading. Sulfoxides could also be selectively produced in ethanol, which makes the title methodology a good alternative for both sulfoxide and sulfone production. The separation and recycling of the catalyst and oxidant by-products were simple, effective and economical in this clean oxidation method. The FT-IR, UV-vis and leaching experiments after ten successive cycles showed that the catalyst was most strongly anchored to the MWCNT support. The Royal Society of Chemistry 2014.
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh
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p. 1960 - 1969
(2014/06/24)
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- Catalytic activity and selectivity of reusable α-MoO3 nanobelts toward oxidation of olefins and sulfides using economical peroxides
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The novel catalytic activity of α-MoO3 nanobelts prepared by a new and safe sol-gel method for the epoxidation of olefins and oxidation of sulfides to sulfoxides using H2O2 in ethanol as a safe solvent has been exploited. The reactions also proceeded efficiently in the presence of tert-butyl hydroperoxide (TBHP). Good/high yields and excellent selectivity resulted. The ammonia TPD profile demonstrated strong acidic sites in synthesized α-MoO3 nanobelts, which generated different catalytic activity than the bulk material. The separation and reuse of this heterogeneous nanocatalyst was simple, effective and economical in the presented oxidation methods.
- Jafarpour, Maasoumeh,Ghahramaninezhad, Mahboube,Rezaeifard, Abdolreza
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p. 1601 - 1608
(2014/01/06)
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- Silica-coated magnetite nanoparticles stabilized simple Mn-tetraphenylporphyrin for aqueous phase catalytic oxidations with tert-butyl hydroperoxide
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An economic and environmentally friendly system for efficient and selective oxidation of industrially and biologically important substrates in water using tert-butyl hydroperoxide catalyzed by a new magnetically recoverable Mn-porphyrin was developed. The easily prepared heterogeneous catalyst was characterized by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, FT-IR and UV-vis spectroscopy. The size of the catalyst was estimated to be about 10 nm. The thermal gravimetric analysis demonstrated that the nanocatalyst was thermally stable up to almost 300 °C. The reactivity, selectivity and scope of the reaction were investigated with a variety of olefins, saturated hydrocarbons, alcohols and organosulfur compounds. The reactions proceeded smoothly in the absence of surfactants, organic co-solvents and thus take place "on water". The separation and recycling of nanocatalyst as well as isolation of water-insoluble products were simple, effective and economical in this clean oxidation method.
- Rezaeifard, Abdolreza,Farshid, Parisa,Jafarpour, Maasoumeh,Moghaddam, Gholamreza Kardan
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p. 9189 - 9196
(2014/03/21)
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- Function-oriented investigations of a peptide-based catalyst that mediates enantioselective allylic alcohol epoxidation.
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We detail an investigation of a peptide-based catalyst (6) that is effective for the site- (>100 - 1 - 1) and enantioselective epoxidation (86% ee) of farnesol. Studies of the substrate scope exhibited by the catalyst are included, along with an exploration of optimized reaction conditions. Mechanistic studies are reported, including relative rate determinations for the catalyst and propionic acid, a historical perspective, truncation studies, and modeling using NMR data. Our compiled data advances our understanding of the inner workings of a catalyst that was identified through combinatorial means.
- Abascal, Nadia C.,Lichtor, Phillip A.,Giuliano, Michael W.,Miller, Scott J.
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p. 4504 - 4511
(2015/02/19)
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- Niobium peroxide-catalyzed selective epoxidation of allylic alcohols
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Modified niobium peroxides were prepared and used for catalyzing the epoxidation of allylic alcohols with hydrogen peroxide in the absence of any other solvent under ice bath conditions. Niobium peroxides modified with ionic liquid-type 1-dodecyl- 3-methylimidazolium hydroxide or conventional tetradecyl trimethyl ammonium hydroxide surfactants demonstrated excellent yields (80-99%) for the epoxidation of allylic alcohols to their epoxides even if the reaction was performed without any other solvent at 0°C for 0.5 h. The catalyst characterization demonstrated that the surfactant molecules were anchored on the surface of the niobium catalyst by weak noncovalent interactions. Compared with niobium peroxides, the modified amphiphilic catalysts allowed easier accessibility to hydrophobic substrates and thus demonstrated high reaction rate and excellent recyclability for the epoxidation under mild conditions.
- Chen, Chen,Zhao, Xiuge,Chen, Jizhong,Hua, Li,Zhang, Ran,Guo, Li,Song, Baoning,Gan, Huimei,Hou, Zhenshan
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p. 3231 - 3238
(2015/02/19)
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- Aqueous heterogeneous oxygenation of hydrocarbons and sulfides catalyzed by recoverable magnetite nanoparticles coated with copper(ii) phthalocyanine
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In this work, a novel magnetically recoverable phthalocyanine catalyst was prepared by immobilization of the Cu(ii) phthalocyanine-tetrasulfonic acid tetrasodium complex (CuPcS) on the silica coated magnetic nanoparticles (Fe 3O4@SiO2, SMNP) via the amine functionality (ASMNP). The epoxidation of olefins and the oxidation of saturated hydrocarbons to the related ketones and also sulfides to the sulfones by an aqueous solution of tetra-n-butylammonium peroxomonosulfate (n-Bu4NHSO5, TBAOX) were efficiently enhanced with excellent selectivity under the influence of the catalytic activity of the magnetically separable catalyst. Sulfoxides could also be selectively produced in the mixture of water-ethanol, which makes the title methodology a good alternative for both sulfoxide and sulfone production. The separation and recycling of the catalyst and the reduced form of the oxidant were simple, effective and economical in this clean oxidation method. The FT-IR and leaching experiments after seven successive cycles showed that the catalyst was most strongly anchored to the magnetite nanoparticles.
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Naeimi, Atena,Haddad, Reza
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p. 3386 - 3394
(2013/01/16)
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- An efficient recyclable peroxometalate-based polymer-immobilised ionic liquid phase (PIILP) catalyst for hydrogen peroxide-mediated oxidation
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A linear cation-decorated polymeric support with tuneable surface properties and microstructure has been prepared by ring-opening metathesis polymerisation (ROMP) of a pyrrolidinium-functionalised norbornene-based monomer with cyclooctene. The derived peroxophosphotungstate-based polymer-immobilised ionic liquid phase (PIILP) catalyst is an efficient and recyclable system for the epoxidation of allylic alcohols and alkenes, with only a minor reduction in performance on successive cycles.
- Doherty, Simon,Knight, Julian G.,Ellison, Jack R.,Weekes, David,Harrington, Ross W.,Hardacre, Christopher,Manyar, Haresh
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supporting information; experimental part
p. 925 - 929
(2012/06/18)
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- Highly selective aqueous heterogeneous oxygenation of hydrocarbons catalyzed by recyclable hydrophobic copper (II) phthalocyanine nanoparticles
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A novel aqueous catalytic method for selective epoxidation of olefins and oxidation of saturated hydrocarbons to ketones using aqueous solution of tetra-n-butylammonium peroxomonosulfate (TBAOX) containing water-insoluble copper (II) phthalocyanine nanoparticles has been developed. No surfactants, additives, toxic reagents or solvents were involved. The impressive turnover numbers obtained for CuPc in this oxidation system displayed the high catalytic activity and relative stability of catalyst. The effective dispersity of CuPc in aqueous solution of TBAOX which yielded particles with average size of 30 nm, was the most important factor to affect the reaction rate. The catalyst could easily be recovered and reused without loss of activity and the reduced form of starting oxidant (n-Bu4NHSO4) could also be recycled.
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Naeimi, Atena,Mohammadi, Khosro
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experimental part
p. 141 - 147
(2012/05/20)
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- Nanomagnet-supported partially brominated manganese-porphyrin as a promising catalyst for the selective heterogeneous oxidation of hydrocarbons and sulfides in water
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A novel, magnetically recoverable porphyrin catalyst has been prepared by the coordinative anchoring of the [Mn(Br2TPP)OAc] complex on silica-coated magnetic nanoparticles (Fe3O4@SiO 2, SMNP) through an amine functionality. The heterogeneous catalyst was characterized by powder X-ray diffraction, transmision electron microscopy, scanning electron microscopy, and FTIR spectroscopy. The catalyst loading on the magnetic support was determined by thermogravimetric (TG) analysis and inductively coupled plasma atomic emission spectroscopy. The catalyst nanoparticles were estimated to have a diameter of less than 10 nm. The TG curve demonstrated that the nanocatalyst was thermally stable up to almost 350 °C, exhibiting high thermostability. The epoxidation of olefins and the oxidation of saturated hydrocarbons to the corresponding ketones as well as sulfides to sulfones in an aqueous solution of tetra-n-butylammonium peroxomonosulfate (n-Bu4NHSO5, TBAOX) were efficiently enhanced with excellent selectivity under the influence of the magnetically separable catalyst. Sulfoxides could also be selectively produced in a mixture of water and ethanol, which makes the title methodology a good alternative for both sulfoxide and sulfone production. The separation and recycling of the catalyst and the byproduct of the oxidant were simple, effective, and economic in this clean oxidation method. FTIR and leaching experiments after seven successive cycles showed that the catalyst was very strongly anchored to the SMNP support. Copyright
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Farshid, Parisa,Naeimi, Atena
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p. 5515 - 5524
(2013/01/15)
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- Economical oxygenation of olefins and sulfides catalyzed by new molybdenum(VI) tridentate schiff base complexes: Synthesis and crystal structure
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New cis-dioxomolybdenum(VI) complexes (MoO2YxCH 3OH) were synthesized using MoO2(acac)2 and 2[(1-hydroxy-2-methylpropane-2-ylimino)methyl]phenol derivatives as tridentate ONO donor Schiff base ligands (H2Yx). MoY1 was crystallized in orthorhombic space group Pbca. The epoxidation of olefins using tert-butyl hydroperoxide and oxidation of sulfides to the sulfoxides by hydrogen peroxide were efficiently enhanced by the catalytic activity of title Mo VI complexes with excellent selectivity. The high efficiency and relative stability of the catalysts was observed by turnover number and UV/Vis investigations. The electron-rich and bulky ligands promoted the effectiveness of the catalysts. Copyright
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Raissi, Heidar,Alipour, Mahboubeh,Stoeckli-Evans, Helen
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experimental part
p. 1023 - 1030
(2012/08/07)
-
- Combinatorial evolution of site- and enantioselective catalysts for polyene epoxidation
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Selectivity in the catalytic functionalization of complex molecules is a major challenge in chemical synthesis. The problem is magnified when there are several possible stereochemical outcomes and when similar functional groups occur repeatedly within the same molecule. Selective polyene oxidation provides an archetypical example of this challenge. Historically, enzymatic catalysis has provided the only precedents. Although non-enzymatic catalysts that meet some of these challenges became known, a comprehensive solution has remained elusive. Here, we describe low molecular weight peptide-based catalysts, discovered through a combinatorial synthesis and screening protocol, that exhibit site- and enantioselective oxidation of certain positions of various isoprenols. This diversity-based approach, which exhibits features reminiscent of the directed evolution of enzymes, delivers catalysts that compare favourably to the state-of-the-art for the asymmetric oxidation of these compounds. Moreover, the approach culminated in catalysts that exhibit alternative-site selectivity in comparison to oxidation catalysts previously described.
- Lichtor, Phillip A.,Miller, Scott J.
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p. 990 - 995
(2013/02/25)
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- Peroxometalates immobilized on magnetically recoverable catalysts for epoxidation
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Magnetically separable catalysts were prepared and employed for the epoxidation of olefins with hydrogen peroxide. In all cases the magnetic core was firstly covered with a silica layer to prevent iron ion-initiated decomposition of hydrogen peroxide. The catalytic active species, an ionic liquid-type peroxotungstate, was then immobilized either by hydrogen bonding (catalyst 1) or by covalent SiO linkage (catalyst 2). In addition to a thorough characterization by FT-IR, XRD, NMR, DRIFT, XPS, and TEM, the catalytic potential was evaluated in the epoxidation of a variety of olefins as well as allylic alcohols. Both catalysts showed essentially a constant activity after at least ten consecutive cycles. On the basis of the research above, a new type of magnetically separable catalyst was constructed by immobilization of lacunary-type phosphotungstate by hydrogen bonding between the sulfonate anion and silanol group on the surface of the core-shell magnetic nanoparticles. After the detailed characterization, the catalyst was used in the epoxidation of a variety of olefins and allylic alcohols and was found to possess high activity, selectivity towards epoxides, and a constant activity after at least ten catalytic recycles without solvent.
- Qiao, Yunxiang,Li, Huan,Hua, Li,Orzechowski, Lars,Yan, Kai,Feng, Bo,Pan, Zhenyan,Theyssen, Nils,Leitner, Walter,Hou, Zhenshan
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p. 1128 - 1138
(2013/03/13)
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- A practical innovative method for highly selective oxidation of alcohols in neat water using water-insoluble iron and manganese porphyrins as reusable heterogeneous catalysts
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A novel heterogeneous method for clean and selective oxidation of alcohols to the aldehydes and ketones using tetrabutylammonium peroxomonosulfate (n-Bu4NHSO5) in neat water catalyzed by simple Fe (III) and Mn (III) meso-tetraphenylporphyrin as a water-insoluble catalyst has been developed. The oxidation system proceeds well in the absence of organic co-solvents and surfactants. The presence of an electron-donating group on the phenyl ring of benzyl alcohol increases the reactivity of substrate. The catalysts could easily be recycled and reused without noticeable loss of activity and the oxidant's by-product (n-Bu4NHSO4) could also be recycled.
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Naeimi, Atena
-
experimental part
p. 240 - 244
(2012/02/04)
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- A Ti-substituted polyoxometalate as a heterogeneous catalyst for olefin epoxidation with aqueous hydrogen peroxide
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The Ti-substituted polyoxometalates ([C12mim] 5PTiW11O40, [CTA]5PTiW 11O40 and [TBA]5PTiW11O 40) were prepared and characterized by FT-IR, NMR, UV-vis and ICP-AES. Then the polyoxometalates (POM) were used as catalysts for the epoxidation of various olefins. It was found that the organic countercations had a considerable effect on the catalytic performance. In addition, UV-vis and the FT-IR spectroscopy indicated that the peroxo structure regarded as the active site for oxygen transfer was present even after the reaction, which led to the increasing reaction rate in the second run due to the disappearance of the induction period, as compared with that in the first run. A heterogeneous reaction mechanism has been suggested in olefin epoxidation catalyzed by a Ti-substituted polyoxometalate ([C12mim]5PTiW 11O40) with aqueous hydrogen peroxide in ethyl acetate. The heterogeneous POM catalyst can be easily separated and recycled eight times without decreasing the catalytic activities.
- Hua, Li,Qiao, Yunxiang,Yu, Yinyin,Zhu, Wenwen,Cao, Ting,Shi, Yu,Li, Huan,Feng, Bo,Hou, Zhenshan
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experimental part
p. 1836 - 1841
(2011/10/10)
-
- Epoxidation of olefins with O2 and isobutyraldehyde catalyzed by cobalt (II)-containing zeolitic imidazolate framework material
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Co-containing zeolitic imidazolate framework material (Co-ZIF) was prepared and its catalytic performance in the aerobic epoxidation of olefins using isobutyraldehyde as reductant under mild conditions was first studied. Co-ZIF was characterized by XRD, FT-IR and X-ray single-crystal diffraction. It showed good performance in the epoxidation of olefins, with 100% conversion, 98.5% selectivity and 638.3 turnover frequency for the epoxidation of cyclooctene. Co-ZIF could be reused for 5 times without loss of its catalytic activity and the structure of the recovered catalyst was almost unchanged compared to that of the fresh one.
- Zhang, Aiping,Li, Linqing,Li, Jun,Zhang, Yi,Gao, Shuang
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experimental part
p. 1183 - 1187
(2012/05/20)
-
- Synthesis, characterization and pronounced epoxidation activity of cis-dioxo-molybdenum(VI) tridentate Schiff base complexes using tert-butyl hydroperoxide
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The synthesis and catalytic performance of novel cis-dioxo-Mo(VI) complexes containing simple ONO tridentate Schiff base ligands in the epoxidation of various olefins using tert-butyl hydroperoxide in desired times with excellent chemo- and stereoselectivity have been described. The study of turnover numbers and the UV-Vis spectra of the Mo complexes in the present epoxidation system indicate well the high efficiency and stability of the catalysts during the reaction. The electron-deficient and bulky groups on the salicylidene ring of the ligand promote the effectiveness of the catalyst.
- Rezaeifard, Abdolreza,Sheikhshoaie, Iran,Monadi, Niaz,Alipour, Mahboubeh
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experimental part
p. 2703 - 2709
(2011/01/10)
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- Polymer-supported Oxone and tert-butyl hydroperoxide: new reagents for the epoxidation of α,β-unsaturated aldehydes and ketones
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Efficient, mild and selective epoxidation of α,β-unsaturated aldehydes and ketones was performed using polyvinylpyrrolidonesupported Oxone (Oxone/PVP) and ButOOH/PVP.
- Pourali, Ali Reza
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experimental part
p. 113 - 115
(2010/06/19)
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- Synthesis, crystal structure, and catalytic properties of novel dioxidomolybdenum(VI) complexes with tridentate schiff base ligands in the biomimetic and highly selective oxygenation of alkenes and sulfides
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Four novel dioxidomolybdenum(VI) complexes [MoO2(L x)(CH3OH)] have been synthesized, using 2[(E)-(2-hydroxy-2-phenylethylimino)methyl]phenol derivatives as tridentate ONO donor Schiff base ligands (H2Lx) and MoO 2(acac)2. A monoclinic space group was determined by X-ray crystallography from single-crystal data of a sample of these new complexes. The epoxidation of alkenes by using tert-butyl hydroperoxide and oxidation of sulfides to sulfoxides by urea hydrogen peroxide were efficiently enhanced with excellent selectivity under the catalytic influence these new MoVI complexes. The high efficiency and relative stability of the catalysts have been observed, by turnover numbers and UV/Vis investigations. The electron-poor and bulky ligands promoted the effectiveness of the catalysts. 2010 Wiley-VCH Verlag GmbH & Co. KGaA.
- Rezaeifard, Abdolreza,Sheikhshoaie, Iran,Monadi, Maz,Stoeckli-Evans, Helen
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experimental part
p. 799 - 806
(2010/07/04)
-