3234-26-2Relevant academic research and scientific papers
Olefin epoxidation in solventless conditions and apolar media catalysed by specialised oxodiperoxomolybdenum complexes
Herbert, Matthew,Montilla, Francisco,Galindo, Agustín
, p. 111 - 120 (2011)
The epoxidation of olefin substrates, in both apolar organic media and under solventless conditions, with aqueous hydrogen peroxide and catalysed by molybdenum complexes has been investigated. The catalysts compounds employed were the oxodiperoxomolybdenum complexes of several pyridine, 2,2′-bipyridine and pyrazole ligands with apolar functions (alkyl chains, alkyl-trimethylsilyl groups and polydimethylsiloxanyl polymer), which showed enhanced solubility in relatively apolar organic media. Both the isolated complexes and in situ preparations were catalytically active. The solubility of the new catalyst complexes appears to facilitate the catalytic activity in these systems, since activity was not observed for the analogous, insoluble complexes of unfunctionalised ligands. In these systems, the oxidant, aqueous hydrogen peroxide, forms a separate phase and the catalyst resides in the organic phase. From a green chemistry and economic perspective the elimination of organic solvents and co-catalysts from a reaction system would present advantages and, consequently, the epoxidation reaction was also investigated under solventless conditions. The 3-hexyl-5-methylpyrazole and 3-hexyl-5-heptylpyrazole complexes were found to show heightened activities, the latter being particularly efficient in these conditions, whilst bipyridines apparently inhibit the epoxidation. In addition, the mechanism of the epoxidation reaction was studied through DFT calculations for the model olefin substrate ethylene with the oxodiperoxomolybdenum complex of 3-hexyl-5-heptylpyrazole. The oxo-transfer reaction occurred by interaction of the ethylene with the peroxo ligand via the spirocyclic transition state proposed by Sharpless.
Molybdenum hexacarbonyl supported on amine modified multi-wall carbon nanotubes: An efficient and highly reusable catalyst for epoxidation of alkenes with tert-butylhydroperoxide wileyonlinelibrary.com
Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Sadat Mirbagheri, Naghmeh
, p. 708 - 713 (2010)
In the present work, highly efficient epoxidation of alkenes catalyzed by Mo(CO)6 supported on multi-wall carbon nanotubes modified by 2-aminopyrazine, APyz-MWCNTs, is reported. The prepared catalyst was characterized by elemental analysis, scanning electron microscopy, FT IR and diffuses reflectance UV-vis spectroscopic methods. This new heterogenized catalysts, [Mo(CO)6@APyz-MWCNT], was used asa highly efficient catalyst for epoxidation of alkenes with tert-BuOOH. This robust catalyst was reused several times without loss of its catalytic activity. Copyright
Synthesis, characterization and catalytic activity of supported vanadium Schiff base complex as a magnetically recoverable nanocatalyst in epoxidation of alkenes and oxidation of sulfides
Bagherzadeh, Mojtaba,Bahjati, Mohammad,Mortazavi-Manesh, Anahita
, p. 200 - 206 (2019)
A new magnetically separable nanocatalyst was successfully synthesized by immobilizing of vanadyl acetylacetonate complex, [VO(acac)2], onto silica coated magnetite nanoparticles previously functionalized with 3-aminopropyltriethoxysilane (3-APTES) and reacted by 5-bromosalicylaldehyde to form Schiff base moiety. The obtained nanocatalyst was characterized by elemental analysis (CHN), FT-IR spectroscopy, Powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), inductively coupled plasma optical emission spectrometry (ICP-OES) and thermogravimetric analysis (TGA). Eventually, the resulting nanoparticles were used as catalyst for epoxidation of alkenes and oxidation of sulfides using tert-butyl hydroperoxide (TBHP) as an oxidant.
Isolation and Molecular Structure of Unusual Oxochromium(V) Cations for the Catalytic Epoxidation of Alkenes
Siddall, Thomas L.,Miyaura, Norio,Huffman, John C.,Kochi, Jay K.
, p. 1185 - 1186 (1983)
The first X-ray crystal structure of an oxochromium(V) complex capable of effecting oxygen atom transfer to alkenes in stoicheiometric and catalytic systems is reported.
Ionic liquid surfactants as multitasking micellar catalysts for epoxidations in water
Cokoja, Mirza,Jess, Andreas,Korth, Wolfgang,Schmidt, Fabian,Zehner, Bastian
, p. 4448 - 4457 (2020)
We present a single-component catalyst system for the epoxidation of hydrophobic olefins in aqueous solution. The aggregation of surface-active 1-alkyl-3-methylimidazolium ionic liquids (IL) containing the catalytically active tungstate dianion leads to micelles, which solubilise apolar olefins in aqueous media. The micellisation of tungstate allows for the epoxidation of cyclooctene and other olefins in water, using environmentally benign hydrogen peroxide as oxidant. The structural characterisation of the micelles under catalysis conditions as well as the substrate uptake have been studied by cryo-TEM. 183W-NMR studies revealed that the catalytically active species is a tetraperoxotungstate complex. The addition of organophosphonic acids results in a significant boost of the catalytic activity by formation of a tungstate-phosphonate adduct, investigated using electrospray ionisation mass spectrometry (ESI-MS). The versatile functionalisability of the imidazolium cation enables a covalent linkage of a phosphonate group, which is further increasing the catalytic activity.
Polyoxotungstate incorporating organotriphosphonate ligands: Synthesis, characterization, and catalytic for alkene epoxidation
Huo, Yu,Huo, Zhiyuan,Ma, Pengtao,Wang, Jingping,Niu, Jingyang
, p. 406 - 408 (2015)
A S-shaped organotriphosphonate polyoxotungstate, K4H6[H4{(AsW9O33)Zn(H2O)W5O11(N(CH2PO3)3)}2(μ2-O)2]·27H2O (1), has been synthesized and characterized. Compound 1 contains a different geometry of [{Zn(H2O)W5O19(N(CH2PO3)3)}]12- clusters, which forms a chiral conformation. The catalysis of 1 for alkene epoxidation was investigated with a hydrogen peroxide (H2O2) oxidant.
Olefin epoxidation with ionic liquid catalysts formed by supramolecular interactions
Ding, Bingjie,Hou, Zhenshan,Li, Difan,Ma, Wenbao,Yao, Yefeng,Zhang, Ran,Zheng, Anna,Zhou, Qingqing
, (2020/12/29)
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.
Nonheme manganese(III) complexes for various olefin epoxidation: Synthesis, characterization and catalytic activity
Lee, Sojeong,Park, Soyoung,Lee, Myoung Mi,Lee, Jiyoung,Kim, Cheal
, (2021/03/14)
Three mononuclear imine-based non-heme manganese(III) complexes with tetradentate ligands which have two deprotonated phenolate moieties, ([(X2saloph)Mn(OAc)(H2O)], 1a for X = Cl, 1b for X = H, and 1c for X = CH3, saloph = N,N-o-phenylenebis(salicylidenaminato)), were synthesized and characterized by 1H NMR, 13C NMR, ESI-Mass and elemental analysis. MnIII complexes catalysed efficiently various olefin epoxidation reactions with meta-chloroperbenzoic acid (MCPBA) under the mild condition. MnIII complexes 1a and 1c with the electron-withdrawing group -Cl and electron-donating group –CH3 showed little substituent effect on the epoxidation reactions. Product analysis, Hammett study and competition experiments with cis- and trans-2-octene suggested that MnIV = O, MnV = O, and MnIII-OOC(O)R species might be key oxidants in the epoxidation reaction under this catalytic system. In addition, the use of PPAA as a mechanistic probe demonstrated that Mn-acylperoxo intermediate (MnIII-OOC(O)R) 2 generated from the reaction of peracid with manganese complexes underwent both the heterolysis and the homolysis to produce MnV = O (3) or MnIV = O species (4). Moreover, the MnIII-OOC(O)R 2 species could react directly with the easy-to-oxidize substrate to give epoxide, whereas the species 2 might not be competent to the difficult-to-oxidize substrate for the epoxidation reaction.
Enantioselective, Stereoconvergent Resolution Copolymerization of Racemic cis-Internal Epoxides and Anhydrides
He, Guang-Hui,Ren, Bai-Hao,Chen, Shi-Yu,Liu, Ye,Lu, Xiao-Bing
supporting information, p. 5994 - 6002 (2021/02/11)
Unprecedented enantioselective resolution copolymerization of racemic cis-internal epoxides and anhydrides was mediated by dinuclear aluminum complexes with multiple chirality, affording optically active polyesters with two contiguous stereogenic centers, and the unreacted substrates in good enantioselectivity. Unexpected stereoconvergence is observed in this resolution copolymerization, where the selectivity factor for the enantioselective formation of copolymer significantly exceeds the kinetic resolution coefficient based on the unreacted epoxide at various conversions. Catalytic activity and copolymer enantioselectivity are strongly influenced by the phenolate ortho-substituents of the ligand set, as well as the axial linker and its chirality. An enantiopure binaphthol-linked bimetallic AlIII complex allows stereoconvergent access to the stereoregular semi-crystalline polyesters and a concomitant kinetic resolution of the epoxide substrates.
Activation of hydrogen peroxide by the nitrate anion in micellar media
Schmidt, Fabian,Zehner, Bastian,Kaposi, Marlene,Drees, Markus,Mink, János,Korth, Wolfgang,Jess, Andreas,Cokoja, Mirza
supporting information, p. 1965 - 1971 (2021/03/26)
We present the activation of hydrogen peroxide by micellar imidazolium nitratesviaH-bond formation in water, as shown by vibrational spectroscopy and supported by DFT calculations. Mechanistic insight into the interactions of the surfactant cation, the nitrate anion and H2O2is given. The micelles solubilise and epoxidise cyclooctene in the aqueous phase.
