- Synthesis of poly(ethylene glycol)-supported manganese porphyrines: Efficient, recoverable and recyclable catalysts for epoxidation of alkenes
-
Two new poly(ethylene glycol) supported manganese porphyrins have been prepared and their catalytic activity and recyclability were investigated for the epoxidation of alkenes using H2O2 and PhIO as stoichiometric oxidants.
- Benaglia, Maurizio,Danelli, Tamara,Pozzi, Gianluca
-
-
Read Online
- Epoxidation of olefins by molecular oxygen over supported metal heterogeneous catalysts
-
Molecular oxygen (1 atm) conveniently reacts with olefins in the presence of simple supported metal heterogeneous catalysts and aldehydes (e.g., isobutyraldehyde and benzaldehyde) at room temperature to give epoxides in good yields.
- Gao, Hanrong,Angelici, Robert J.
-
-
Read Online
- A new methodology for synthesis of 1,2-epoxy alkane with the linear aliphatic olefins in presence of molecular oxygen
-
The linear aliphatic olefins, such as 1-octene, 1-decene, 1-dodecene and 1-tetradecene, were effectively epoxidized with molecular oxygen catalyzed by the amino acid Schiff base manganese complex (Sal-Phe-Mn). The products of the reaction was 1,2-epoxy alkane.
- Wang,Hao,Wang
-
-
Read Online
- Efficient epoxidation of cyclododecene and dodecene catalysed by polybenzimidazole supported Mo(VI) complex
-
A polybenzimidazole supported Mo(VI) complex (PBI.Mo) has been prepared and characterised. The catalytic activity of PBI.Mo for the epoxidation of cyclododecene and dodecene with tert-butyl hydroperoxide (TBHP) as an oxidant has been studied under different reaction conditions in a batch reactor. The stability of heterogeneous Mo(VI) catalyst was evaluated by recycling a sample in batch reaction using conditions that will form the basis of continuous process. The leaching of Mo species from PBI.Mo has been investigated by isolating any residue from reaction supernatant solutions following the removal of the heterogeneous catalyst, then using the residues as potential catalyst in epoxidation reactions. The batch epoxidation experimental data provided useful information for conducting continuous epoxidation in a reactive distillation column (RDC).
- Mbeleck, Rene,Mohammed, Misbahu Ladan,Ambroziak, Krzysztof,Sherrington, David C.,Saha, Basudeb
-
-
Read Online
- Ruthenium Nanoparticles Immobilized on Nano-silica Functionalized with Thiol-Based Dendrimer: A Nanocomposite Material for Oxidation of Alcohols and Epoxidation of Alkenes
-
Abstract: In this work, ruthenium nanoparticles were immobilized on thiol-based dendrimer functionalized nano-silica and its catalytic activity was investigated in the oxidation reactions. To do this, silica nanoparticles were functionalized with a thiol-
- Haghshenas Kashani, Sara,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
-
-
Read Online
- Investigation of physicochemical properties for novel perrhenate ionic liquid and its catalytic application towards epoxidation of olefins
-
Abstract: A novel ionic liquid (IL) based on catalytic functional metal rhenium, [Smim][ReO4] (1-heptyl-3-methyl-imidazolium perrhenate) was synthesized and characterized. Density and surface tension values of the IL were determined at different temperatures, and the volume and surface properties were calculated and discussed, respectively. Furthermore, the synthesized ionic liquid [Smim][ReO4] was used as a green solvent and catalyst for homogeneous catalyzed epoxidation of olefin with urea hydrogen peroxide (UHP) oxidant. The effect of factors of catalyst, oxidant, reaction time, and reaction temperature was discussed. The conversion of cyclohexene and cyclooctene is over 99% at optimum conditions. The IL [Smim][ReO4] as catalyst and solvent are characterized by high efficiency, long service life and recoverability, which is a better green homogeneous catalyst for epoxidation of olefins. Graphic Abstract: A novel IL based on catalytic functional metal rhenium, [Smim][ReO4] was synthesized and characterized. The volume and surface properties were calculated and discussed by the density and surface tension values at different temperatures, respectively. Furthermore, the as-synthesized [Smim][ReO4] was used as a green solvent and catalyst for homogeneous catalyzed epoxidation of olefin with urea hydrogen peroxide (UHP) oxidant. The results showed that the yield and selectivity of the reaction were up to 99%, and the catalytic efficiency of [Smim][ReO4] did not decrease significantly after five times recycling. Easy separation, recycle, nontoxicity and homogeneous catalysis are the main advantages of perrhenate ionic liquids over other heterogeneous catalysts containing organic solvents.[Figure not available: see fulltext.].
- Song, Zongren,Liu, Xueke,Zhang, Hao,Fang, Dawei,Ma, Xiaoxue
-
-
Read Online
- A new protocol for in situ dioxirane reactions: Stoichiometric in oxone and catalytic in fluorinated acetophenones
-
(Matrix presented) Dioxiranes made in situ from the commercially available tetrafluoroacetophenones (7, 8) and pentafluoroacetophenone (9) are reported for highly efficient epoxidation of olefins for the first time. Studies showed that ketone 7, 8, or 9 c
- Li, Wei,Fuchs, Philip L.
-
-
Read Online
- Efficient and selective oxidation of hydrocarbons with tert-butyl hydroperoxide catalyzed by oxidovanadium(IV) unsymmetrical Schiff base complex supported on γ-Fe2O3 magnetic nanoparticles
-
The catalytic activity of an oxidovanadium(IV) unsymmetrical Schiff base complex supported on γ-Fe2O3 magnetic nanoparticles, γ-Fe2O3@[VO(salenac-OH)] in which salenac-OH = [9-(2′,4′-dihydroxyphenyl)-5,8-diaza-4
- Samani, Mahnaz,Ardakani, Mehdi Hatefi,Sabet, Mohammad
-
p. 1481 - 1494
(2022/01/22)
-
- Dioxo-molybdenum(VI) unsymmetrical Schiff base complex supported on CoFe2O4@SiO2 nanoparticles as a new magnetically recoverable nanocatalyst for selective epoxidation of alkenes
-
In the present work, a dioxo-molybdenum unsymmetrical Schiff base complex, [MoO2(salenac-OH)], in which salenac-OH = [9-(2',4'-dihydroxyphenyl)-5,8-diaza-4-methylnona-2,4,8-trienato](-2), has been prepared and covalently immobilized on the sili
- Ardakani, Mehdi Hatefi,Sabet, Mohammad,Samani, Mahnaz
-
-
- Iron-Catalyzed Epoxidation of Linear α-Olefins with Hydrogen Peroxide
-
The combination of Fe(OTf)2 with N-methyl bis(picolylamine) (Me-bpa) L7 enables epoxidation of linear olefins including terminal, internal, and cyclic ones, using hydrogen peroxide as terminal oxidant under mild conditions. In the presence of picolinic acid as additive improved yields of epoxides up to 75 % have been achieved.
- Mao, Shuxin,Budweg, Svenja,Spannenberg, Anke,Wen, Xiaodong,Yang, Yong,Li, Yong-Wang,Junge, Kathrin,Beller, Matthias
-
-
- Synthesis, characterization and catalytic activities of nonheme manganese(III) complexes: Preferential formation of cis olefin oxide owing to steric hindrance
-
Three mononuclear nonheme MnIII(salophen) complexes, 1a-1c, with tetradentate ligands containing two deprotonated phenolates ([(X2-tert-butyl-salophen)Mn(OAc)(H2O)] (tert-butyl-salophen = N,N′-bis(6-di-tert-butylsalicylidene)-1,2-phenylenediaminato, 1a for X = Cl, 1b for X = H, and 1c for X = CH3)) were synthesized and characterized using 1H NMR, 13C NMR, elemental analysis and ESI-Mass spectrometry. These Mn(III) complexes were used to efficiently catalyze the epoxidation reactions of diverse aliphatic, aromatic and terminal alkenes to form the corresponding epoxides with MCPBA (m-chloroperoxybenzoic acid) as an oxidant under mild conditions. Notably, catalysts 1a-1c preferably react with the cis-alkene because of the steric hindrance between the reactive intermediate MnIII-OOC(O)R and the trans-type substrate. A Hammett study and product analysis using PPAA (peroxyphenylacetic acid) as a mechanistic indicator suggested that the peracid reacted with the Mn(III) complex to generate the MnIII-OOC(O)R intermediate, which underwent both homolysis and heterolysis to form MnIV=O or MnV=O. The reactive MnV=O might participate in the alkene epoxidation with good stereospecificity, whereas the MnIV=O species might trigger radical-type oxidation to produce non-stereospecific by-products, such as ketones and aldehyde. On the other hand, MnIII-OOC(O)R (2) could oxidize the reactive cyclohexene to the epoxide, whereas it was unable to epoxidize the poorly reactive 1-octene.
- Kim, Cheal,Lee, Jiyoung,Moon, Sungjin,Park, Soyoung
-
-
- A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles
-
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
-
supporting information
p. 519 - 526
(2021/03/31)
-
- Proton Switch in the Secondary Coordination Sphere to Control Catalytic Events at the Metal Center: Biomimetic Oxo Transfer Chemistry of Nickel Amidate Complex
-
High-valent metal-oxo species are key intermediates for the oxygen atom transfer step in the catalytic cycles of many metalloenzymes. While the redox-active metal centers of such enzymes are typically supported by anionic amino acid side chains or porphyrin rings, peptide backbones might function as strong electron-donating ligands to stabilize high oxidation states. To test the feasibility of this idea in synthetic settings, we have prepared a nickel(II) complex of new amido multidentate ligand. The mononuclear nickel complex of this N5 ligand catalyzes epoxidation reactions of a wide range of olefins by using mCPBA as a terminal oxidant. Notably, a remarkably high catalytic efficiency and selectivity were observed for terminal olefin substrates. We found that protonation of the secondary coordination sphere serves as the entry point to the catalytic cycle, in which high-valent nickel species is subsequently formed to carry out oxo-transfer reactions. A conceptually parallel process might allow metalloenzymes to control the catalytic cycle in the primary coordination sphere by using proton switch in the secondary coordination sphere.
- Kim, Soohyung,Jeong, Ha Young,Kim, Seonghan,Kim, Hongsik,Lee, Sojeong,Cho, Jaeheung,Kim, Cheal,Lee, Dongwhan
-
supporting information
p. 4700 - 4708
(2021/02/12)
-
- Fast-synthesis and catalytic property of heterogeneous Co-MOF catalysts for the epoxidation of α-pinene with air
-
In the past decades, many methods have been developed for synthesizing MOFs, including solvothermal synthesis, mechanical synthesis, electrochemical synthesis, and microwave synthesis. Based on the existing research, a method is proposed for synthesizing Co-MOF by rapidly rotating hydrothermal crystallization, which largely shortens the crystallization time of Co-MOF. When the rotation speed was 150 rpm, only 2 h of crystallization time was needed to synthesize Co-MOF-150-2 with high crystallinity and stability. The optimal Co-MOF-150-2 manifested remarkable activity and selectivity for the epoxidation of α-pinene under mild conditions. The catalytic conversion of α-pinene reached the highest over the Co-MOF-150-2 catalyst, in which the conversion of α-pinene was 99.5% and the yield of 2,3-epoxypinane was 95.7%. The Co-MOF materials synthesized by the rotary method also had excellent stability and highly catalytic activity in recycling experiments. This journal is
- Zhang, Haifu,He, Jie,Lu, Xinhuan,Yang, Lu,Wang, Chenlong,Yue, Fanfan,Zhou, Dan,Xia, Qinghua
-
p. 17413 - 17421
(2020/11/02)
-
- METHOD FOR PRODUCING 1,2-ALKANEDIOL
-
The present application relates to a method for producing 1,2-alkanediol. The method for producing 1,2-alkanediol of the present invention is industrially very simple compared to a chemical equation 1, which is a conventional method.COPYRIGHT KIPO 2020
- -
-
Paragraph 0088-0089
(2020/08/20)
-
- Method for preparing epoxide by one-pot olefin aerobic epoxidation
-
The invention relates to a method for preparing an epoxide by one-pot olefin aerobic epoxidation, and belongs to the technical field of organic synthesis. An olefin, an alkyl aromatic compound and analkali are added into a solvent, or an olefin, an alkyl aromatic compound and an alkali are directly mixed; the temperature is raised to 70-160 DEG C in an air or oxygen atmosphere; reacting is carried out for 1-48 hours; and the olefin is directly oxidized into the corresponding epoxide in the presence of the alkyl aromatic compound, the alkali and air (or oxygen), wherein the yield is up to 99%.In the reaction process, the generated alkyl peroxide is generated in situ and consumed in situ, so that the concentration of the alkyl peroxide is kept at a lower level; and generated alkyl peroxy free radicals can also react with the olefin to further generate the peroxide, and efficiency is improved. The method has the advantages of simple operation, mild conditions, low raw material cost andno need of special complex equipment, and has a good industrial application prospect.
- -
-
Paragraph 0072-0073
(2020/01/03)
-
- Oxidative Cleavage of Long-Chain Terminal Alkenes to Carboxylic Acids
-
Oxidation of aliphatic terminal alkenes having more than 30 carbon atoms to carboxylic acids is presented. Such long carboxylic acids are useful as waxes, lubricants, plasticizers, etc. The oxidation was conducted under solvent-free conditions or with small amounts of diluents (heptane, methylcyclohexane, and tert-butylbenzene). Hydrogen peroxide was used as the oxidant, and tungstic acid was used as the catalyst. Halogen-free quaternary ammonium salts were used as phase-transfer catalysts, and the importance of the elimination of halide ions is discussed. Purification of the crude oxidized product and tungsten removal are also presented. The products have a maximum acid number of 75 mg of KOH/g, a saponification number of 100 mg of KOH/g, and tungsten content below 400 ppm.
- Pyszny, Dariusz,Piotrowski, Tomasz,Orlińska, Beata
-
-
- Oxidative Cleavage of Long-Chain Terminal Alkenes to Carboxylic Acids
-
Oxidation of aliphatic terminal alkenes having more than 30 carbon atoms to carboxylic acids is presented. Such long carboxylic acids are useful as waxes, lubricants, plasticizers, etc. The oxidation was conducted under solvent-free conditions or with small amounts of diluents (heptane, methylcyclohexane, and tert-butylbenzene). Hydrogen peroxide was used as the oxidant, and tungstic acid was used as the catalyst. Halogen-free quaternary ammonium salts were used as phase-transfer catalysts, and the importance of the elimination of halide ions is discussed. Purification of the crude oxidized product and tungsten removal are also presented. The products have a maximum acid number of 75 mg of KOH/g, a saponification number of 100 mg of KOH/g, and tungsten content below 400 ppm.
- Pyszny, Dariusz,Piotrowski, Tomasz,Orlińska, Beata
-
p. 309 - 319
(2019/03/21)
-
- 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane: An efficient and high oxygen content oxidant in various oxidative reactions
-
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
-
supporting information
p. 6584 - 6592
(2018/10/05)
-
- Non-redox metal ions accelerated oxygen atom transfer by Mn-Me3tacn complex with H2O2 as oxygen resource
-
This work demonstrates a novel strategy that the introduction of non-redox metal ions as Lewis acids to the classic dinuclear manganese complex [MnIV2(μ-O)3(Me3tacn)2](PF6)2 can greatly promote the alkene epoxidation efficiency under mild conditions with H2O2 as the solely terminal oxidant because of its economic and environmental advantages. When [MnIV2(μ-O)3(Me3tacn)2](PF6)2 was used as the catalyst in the absence of Lewis acids, only 16.4% conversion of cyclooctene with 6.2% yield of epoxide was obtained and the obvious decomposition of H2O2 was observed. However, the oxygen transfer efficiency of the catalyst was sharply improved with 100% conversion and 90.2% yield of epoxide under identical conditions when the non-redox metal ion, such as Sc3+, was introduced to the catalytic system. The novel strategy was successfully applied to the epoxidation reactions of different types of alkenes. Through UV–vis, FT-IR, EPR and CV characterizations, it was evidenced that the non-redox metal ions with high positive charge as Lewis acids could dissociate the sluggish dinuclear Mn-(μ-O)3-Mn core and the open-loop dinuclear manganese complex, HO-MnIII-(μ-O)-MnIV = O or O = MnIV-(μ-O)-MnIV = O, was proposed as the active species, which was capable of the alkene epoxidation process. This work illustrated an alternative protocol to manipulate the reactivity of those sluggish catalysts by the introduction of non-redox metal ions and provided clues to understand the role of non-redox metal ions in metalloenzymes and heterogeneous catalysts.
- Lv, Zhanao,Choe, Cholho,Wu, Yunfeng,Wang, Haibin,Chen, Zhuqi,Li, Guangxing,Yin, Guochuan
-
-
- Dinuclear Iron(III) and Nickel(II) Complexes Containing N-(2-Pyridylmethyl)-N′-(2-hydroxyethyl)ethylenediamine: Catalytic Oxidation and Magnetic Properties
-
Dinuclear FeIII and NiII complexes, [(phenO)Fe(N3)]2(NO3)2 (1) and [(phenOH)Ni(N3)2]2 (2), were prepared by treating Fe(NO3)3?9 H2O and Ni(NO3)2?6 H2O in methanol, respectively, with phenOH (=N-(2-pyridylmethyl)-N′-(2-hydroxyethyl)ethylenediamine) and NaN3; both 1 and 2 were characterized by elemental analysis, IR spectroscopy, X-ray diffraction, and magnetic susceptibility measurements. Two ethoxo-bridged FeIII and two azido-bridged NiII were observed in 1 and 2, respectively; corresponding antiferromagnetic interaction via the bridged ethoxo groups and strong ferromagnetic coupling via the bridged end-on azido ligands within the dimeric unit were observed. Complex 1 did not exhibit any catalytic activity, while 2 exhibited excellent catalytic activities for the epoxidation of aliphatic, aromatic, and terminal olefins.
- Jeong, Ah Rim,Shin, Jong Won,Jeong, Jong Hwa,Bok, Kwon Hee,Kim, Cheal,Jeong, Donghyun,Cho, Jaeheung,Hayami, Shinya,Min, Kil Sik
-
p. 3023 - 3033
(2017/03/13)
-
- Transformation of Methylene Acetals to Bromoformates with a Combination of Trimethyl(phenylthio)silane and N-Bromosuccinimide
-
A novel transformation reaction of methylene acetals, using a combination of trimethyl(phenylthio)silane (PhSTMS) and N-bromosuccinimide (NBS) under mild reaction conditions, is described. Various methylene acetals were converted to their corresponding br
- Maegawa, Tomohiro,Nogata, Misa,Hirose, Yuuka,Ohgami, Shun,Nakamura, Akira,Miki, Yasuyoshi,Fujioka, Hiromichi
-
p. 7608 - 7613
(2017/07/26)
-
- Trinuclear nickel and cobalt complexes containing unsymmetrical tripodal tetradentate ligands: Syntheses, structural, magnetic, and catalytic properties
-
The coordination chemistries of the tetradentate N2O2-type ligands N-(2-pyridylmethyl)iminodiethanol (H2pmide) and N-(2-pyridylmethyl)iminodiisopropanol (H2pmidip) have been investigated with nickel(ii) and cobalt(ii/iii) ions. Three novel complexes prepared and characterized are [(Hpmide)2Ni3(CH3COO)4] (1), [(Hpmide)2Co3(CH3COO)4] (2), and [(pmidip)2Co3(CH3COO)4] (3). In 1 and 2, two terminal nickel(ii)/cobalt(ii) units are coordinated to one Hpmide- and two CH3CO2-. The terminal units are each connected to a central nickel(ii)/cobalt(ii) cation through one oxygen atom of Hpmide- and two oxygen atoms of acetate ions, giving rise to nickel(ii) and cobalt(ii) trinuclear complexes, respectively. Trinuclear complexes 1 and 2 are isomorphous. In 3, two terminal cobalt(iii) units are coordinated to pmidip2- and two CH3CO2-. The terminal units are each linked to a central cobalt(ii) cation through two oxygen atoms of pmidip2- and one oxygen atom of a bidentate acetate ion, resulting in a linear trinuclear mixed-valence cobalt complex. 1 shows a weak ferromagnetic interaction with the ethoxo and acetato groups between the nickel(ii) ions (g = 2.24, J = 2.35 cm-1). However, 2 indicates a weak antiferromagnetic coupling with the ethoxo and acetato groups between the cobalt(ii) ions (g = 2.37, J = -0.5 cm-1). Additionally, 3 behaves as a paramagnetic cobalt(ii) monomer, due to the diamagnetic cobalt(iii) ions in the terminal units (g = 2.53, =D= = 36.0 cm-1). No catalytic activity was observed in 1. However, 2 and 3 showed significant catalytic activities toward various olefins with modest to good yields. 3 was slightly less efficient toward olefin epoxidation reaction than 2. Also 2 was used for terminal olefin oxidation reaction and was oxidised to the corresponding epoxides in moderate yields (34-75%) with conversions ranging from 47-100%. The cobalt complexes 2 and 3 promoted the O-O bond cleavage to ~75% heterolysis and ~25% homolysis.
- Shin, Jong Won,Jeong, Ah Rim,Lee, Sun Young,Kim, Cheal,Hayami, Shinya,Min, Kil Sik
-
p. 14089 - 14100
(2016/11/06)
-
- Selective oxidation of styrene catalyzed by cerium-doped cobalt ferrite nanocrystals with greatly enhanced catalytic performance
-
The rare earth metal Ce-doped cobalt ferrite samples CexCo1?xFe2O4 (x?=?0.1, 0.3, 0.5) were prepared by the sol–gel autocombustion route. The as-prepared samples were characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, ICP–atomic emission spectroscopy, and N2 physisorption. Their catalytic performance was evaluated in oxidation of styrene using hydrogen peroxide (30%) as oxidant. Compared with pristine CoFe2O4, the Ce-doped samples were found to be more efficient catalysts for the oxidation of styrene to benzaldehyde, with greatly enhanced catalytic performance. Especially, when Ce0.3Co0.7Fe2O4 was used as catalyst, 90.3% styrene conversion and 91.5% selectivity for benzaldehyde were obtained at 90?°C for 9?h reaction. The catalyst can be magnetically separated easily for reuse, and no obvious loss of activity was observed when it was reused in five consecutive runs.
- Tong, Jinhui,Li, Wenyan,Bo, Lili,Wang, Huan,Hu, Yusen,Zhang, Zhixia,Mahboob, Abdulla
-
p. 474 - 481
(2016/11/18)
-
- Olefin epoxidation with hydrogen peroxide using octamolybdate-based self-separating catalysts
-
Mo8O264- based organic polyoxomolybdate salts of general formula [Hmim]4Mo8O26 (Hmim = 1-hexyl-3-methylimidazolium), [Dhmim]4Mo8O26 (Dhmim = 1,2-dimethyl-3-hexylimidazolium) and [Hpy]4Mo8O26·H2O (Hpy = 1-hexylpyridinium) have been prepared and characterized. These compounds were applied as catalysts for olefin epoxidation using hydrogen peroxide (H2O2) as oxidant in CH3CN. The polyoxomolybdate salts exhibit excellent catalytic performance and are also self-separating, a great advantage for catalyst recycling. The catalysts can be reused for at least 10 runs without significant loss of activity. This journal is
- Zhou, Ming-Dong,Liu, Mei-Ju,Huang, Liang-Liang,Zhang, Jian,Wang, Jing-Yun,Li, Xue-Bing,Kühn, Fritz E.,Zang, Shu-Liang
-
p. 1186 - 1193
(2015/03/04)
-
- Switching the reaction pathways of electrochemically generated β-haloalkoxysulfonium ions - Synthesis of halohydrins and epoxides
-
β-Haloalkoxysulfonium ions generated by the reaction of electrogenerated Br+ and I+ ions stabilized by dimethyl sulfoxide (DMSO) reacted with sodium hydroxide and sodium methoxide to give the corresponding halohydrins and epoxides, respectively, whereas the treatment with triethylamine gave α-halocarbonyl compounds.
- Shimizu, Akihiro,Hayashi, Ryutaro,Ashikari, Yosuke,Nokami, Toshiki,Yoshida, Jun-Ichi
-
supporting information
p. 242 - 248
(2015/06/01)
-
- Selective Oxidation with Aqueous Hydrogen Peroxide by [PO4{WO(O2)2}4]3- Supported on Zinc-Modified Tin Dioxide
-
We prepared supported phosphorus-containing tetranuclear peroxotungstate ([PO4{WO(O2)2}4]3-, denoted by PW4) catalysts by using zinc-modified SnO2 supports with different zinc contents [PW4-Zn(x)/SnO2, in which x denotes the zinc content (wt%)]. The supported catalysts, in particular PW4-Zn(0.8)/SnO2, could act as efficient and reusable heterogeneous catalysts for selective oxidation with aqueous H2O2 as the terminal oxidant. The catalytic performance of PW4-Zn(0.8)/SnO2 was much superior to those of the corresponding homogeneous analogue THA3PW4 (THA=tetra-n-hexylammonium) and the previously reported tungstate-based heterogeneous catalysts such as our W-Zn/SnO2. In the presence of PW4-Zn(0.8)/SnO2, various types of organic substrates such as alkenes, amines, silanes, and sulfides could be converted into the corresponding oxygenated products in high to excellent yields by using near-stoichiometric amounts of H2O2 with respect to the substrates (typically 1.2 equiv.). The PW4 species interacting with highly dispersed Zn2+ species on SnO2 likely plays an important role in the present oxidation.
- Nojima, Susumu,Kamata, Keigo,Suzuki, Kosuke,Yamaguchi, Kazuya,Mizuno, Noritaka
-
p. 1097 - 1104
(2015/04/14)
-
- Non-redox metal ion promoted oxygen transfer by a non-heme manganese catalyst
-
This work demonstrates that non-redox metal ions as Lewis acids can sharply improve the oxygen transfer efficiency of a manganese(II) catalyst having a non-heme ligand. In the absence of Lewis acid, oxidation of a manganese(II) complex will generate the k
- Chen, Zhuqi,Yang, Ling,Choe, Cholho,Lv, Zhanao,Yin, Guochuan
-
supporting information
p. 1874 - 1877
(2015/02/05)
-
- Redox-inactive metal ions promoted the catalytic reactivity of non-heme manganese complexes towards oxygen atom transfer
-
Redox-inactive metal ions can modulate the reactivity of redox-active metal ions in a variety of biological and chemical oxidations. Many synthetic models have been developed to help address the elusive roles of these redox-inactive metal ions. Using a non-heme manganese(ii) complex as the model, the influence of redox-inactive metal ions as a Lewis acid on its catalytic efficiency in oxygen atom transfer was investigated. In the absence of redox-inactive metal ions, the manganese(ii) catalyst is very sluggish, for example, in cyclooctene epoxidation, providing only 9.9% conversion with 4.1% yield of epoxide. However, addition of 2 equiv. of Al3+ to the manganese(ii) catalyst sharply improves the epoxidation, providing up to 97.8% conversion with 91.4% yield of epoxide. EPR studies of the manganese(ii) catalyst in the presence of an oxidant reveal a 16-line hyperfine structure centered at g = 2.0, clearly indicating the formation of a mixed valent di-μ-oxo-bridged diamond core, MnIII-(μ-O)2-MnIV. The presence of a Lewis acid like Al3+ causes the dissociation of this diamond MnIII-(μ-O)2-MnIV core to form monomeric manganese(iv) species which is responsible for improved epoxidation efficiency. This promotional effect has also been observed in other manganese complexes bearing various non-heme ligands. The findings presented here have provided a promising strategy to explore the catalytic reactivity of some di-μ-oxo-bridged complexes by adding non-redox metal ions to in situ dissociate those dimeric cores and may also provide clues to understand the mechanism of methane monooxygenase which has a similar diiron diamond core as the intermediate.
- Choe, Cholho,Yang, Ling,Lv, Zhanao,Mo, Wanling,Chen, Zhuqi,Li, Guangxin,Yin, Guochuan
-
p. 9182 - 9192
(2015/05/20)
-
- Oxidation of alkenes and sulfides catalyzed by a new binuclear molybdenum bis-oxazoline complex
-
A novel bis(oxazoline) ligand derived from 1,3-dicyanobenzene was prepared and applied as a ligand for the preparation of a new binuclear molybdenyl complex. This ligand was characterized by UV-Vis, mass, 1H NMR, and FT-IR spectroscopic methods, thermal and elemental analysis and X-ray diffraction. The molybdenum complex was prepared by the reaction of this ligand with MoO2(acac)2. The catalyst was also characterized by FT-IR, UV-Vis, and ICP spectroscopy, elemental and thermal analysis. This catalytic system was efficiently used for the oxidation of alkenes and sulfides in the presence of TBHP. The effect of different solvents and kind of oxygen donor was also studied in the oxidation reactions.
- Moshref Javadi, Maedeh,Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Kargar, Hadi,Tahir, Muhammad Nawaz
-
-
- Synthesis of linear aza and thio analogues of acetogenins and evaluation of their cytotoxicity
-
We report the stereoselective synthesis of thio and aza analogues of Annonaceous acetogenins. The synthetic route allows easy variation of the stereochemistry and of the thio- and aza-fragments. Kinetic resolution of terminal bis-epoxides was used to set two remote stereocentres with high enantio- and diastereoselectivities in one step. The cytotoxicity of the analogues was assessed using the HeLa cell line. Four aza and two thio analogues of Annonaceous acetogenins were synthesized according to a general synthetic route. Two remote stereocentres in the analogues were set with high enantio- and diastereoselectivity in one step by hydrolytic kinetic resolution of a terminal bis-epoxide. Copyright
- Villo, Piret,Toom, Lauri,Eriste, Elo,Vares, Lauri
-
p. 6886 - 6899
(2013/11/06)
-
- Rhodium acetate-catalyzed aerobic Mukaiyama epoxidation of alkenes
-
Mukaiyama epoxidation of alkenes under oxygen catalyzed by rhodium acetate with isobutyraldehyde as the reducing agent is as or more effective than previously reported procedures. A variety of alkenes, including terpenes and cholesterol derivatives, were oxidized. And high regioselectivity for monoepoxidation was observed with neryl, geranyl, and linalyl acetates.
- Shabashov, Dmitry,Doyle, Michael P.
-
p. 10009 - 10013
(2013/11/06)
-
- Fe(PyTACN)-catalyzed cis-dihydroxylation of olefins with hydrogen peroxide
-
A family of iron complexes with general formula [Fe(II)( R,Y,XPyTACN)(CF3SO3)2], where R,Y,XPyTACN=1-[2′-(4-Y-6-X-pyridyl)methyl]-4,7-dialkyl-1,4, 7-triazacyclononane, X and Y refer to the groups at positions 4 and 6 of the pyridine, respectively, and R refers to the alkyl substitution at N-4 and N-7 of the triazacyclononane ring, are shown to be catalysts for efficient and selective alkene oxidation (epoxidation and cis-dihydroxylation) employing hydrogen peroxide as oxidant. Complex [Fe(II)(Me,Me,HPyTACN)(CF 3SO3)2] (7), was identified as the most efficient and selective cis-dihydroxylation catalyst among the family. The high activity of 7 allows the oxidation of alkenes to proceed rapidly (30 min) at room temperature and under conditions where the olefin is not used in large amounts but instead is the limiting reagent. In the presence of 3 mol% of 7, 2 equiv. of H2O2 as oxidant and 15 equiv. of water, in acetonitrile solution, alkenes are cis-dihydroxylated reaching yields that might be interesting for synthetic purposes. Competition experiments show that 7 exhibits preferential selectivity towards the oxidation of cis olefins over the trans analogues, and also affords better yields and high [syn-diol]/[epoxide] ratios when cis olefins are oxidized. For aliphatic substrates, reaction yields attained with the present system compare favourably with state of the art Fe-catalyzed cis-dihydroxylation systems, and it can be regarded as an attractive complement to the iron and manganese systems described recently and which show optimum activity against electron-deficient and aromatic olefins. Copyright
- Prat, Irene,Font, David,Company, Anna,Junge, Kathrin,Ribas, Xavi,Beller, Matthias,Costas, Miquel
-
supporting information
p. 947 - 956
(2013/05/08)
-
- The effect of encapsulated Zn-POM on the catalytic activity of MIL-101 in the oxidation of alkenes with hydrogen peroxide
-
Zinc monosubstituted Keggin heteropolyanion [PZnMo2W 9O39]5- was electrostatically bound to nanocages of MIL-101 polymer matrix. The Zn-POM@MIL-101 catalyst was characterized by XRD, N2 adsorption, atomic absorption (AAS), and FT-IR spectroscopic methods. The catalytic activity of the new composite material, Zn-POM@MIL-101, was assessed in the oxidation of alkenes using aqueous hydrogen peroxide as oxidant. Zn-POM@MIL-101/H2O2 catalytic system demonstrated good catalytic activity in the oxidation reactions. Zn-POM@MIL-101 was reusable for three catalytic cycles. While the MIL-101 matrix is an active catalyst in these oxidation reactions, the presence of Zn-POM significantly changed the selectivity and reaction times. Copyright
- Saedi, Zahra,Tangestaninejad, Shaharm,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
-
experimental part
p. 463 - 473
(2012/05/20)
-
- Organocatalyzed epoxidation of alkenes in continuous flow using a multi-jet oscillating disk reactor
-
The times are changing: A batch process, the Minisci epoxidation, is transformed into a continuous-flow protocol for the selective aerobic radical epoxidation of alkenes. The use of a novel reactor type allows to considerably shorten reactor residence times. Experimental results suggest that two different reaction mechanisms exist for the oxidation: one for the batch conditions and a different one for flow synthesis protocol. Copyright
- Spaccini, Raffaele,Liguori, Lucia,Punta, Carlo,Bj?rsvik, Hans-René
-
scheme or table
p. 261 - 265
(2012/05/05)
-
- Structural and dynamical aspects of alkylammonium salts of a silicodecatungstate as heterogeneous epoxidation catalysts
-
The structural and dynamical aspects of alkylammonium salts of a silicodecatungstate [(CH3)4N]4[γ-SiW 10O34(H2O)2] [C1], [(n-C 3H7)4N]4[γ-SiW 10O34(H2O)2] [C3], [(n-C 4H9)4N]4[γ-SiW 10O34(H2O)2] [C4], and [(n-C 5H11)4N]4[γ-SiW 10O34(H2O)2] [C5] were investigated. The results of sorption isotherms, XRD analyses, and solid-state NMR spectroscopy show that facile sorption of solvent molecules, flexibility of structures, and high mobility of alkylammonium cations are crucial to the uniform distribution of reactant and oxidant molecules throughout the bulk solid, which are related to the high catalytic activities for epoxidation of alkenes.
- Uchida, Sayaka,Kamata, Keigo,Ogasawara, Yoshiyuki,Fujita, Megumi,Mizuno, Noritaka
-
supporting information; scheme or table
p. 9979 - 9983
(2012/09/10)
-
- PROCESS FOR MAKING AND USING HOF.RCN
-
The invention relates to a process for making HOF.RCN and using it to oxidise organic substrates in a quick and safe way. The process comprises passing diluted fluorine through a conduit and RCN in water through another conduit into a microreactor to form HOF.RCN and reacting this with an organic substrates.
- -
-
Page/Page column 5
(2011/04/14)
-
- Efficient heterogeneous epoxidation of alkenes by a supported tungsten oxide catalyst
-
Oxidation optimization: A combination of tungsten and zinc oxides on a SnO2 support (W-Zn/SnO2) is a heterogeneous and reusable solid catalyst for selective oxidation with aqueous H2O2. With it, various substrates, such as alkenes, amines, silanes, and sulfides, were oxidized into the corresponding products in high yields (see scheme). The catalyst can be reused several times without an appreciable loss in catalytic performance. Copyright
- Kamata, Keigo,Yonehara, Koji,Sumida, Yasutaka,Hirata, Kazuhisa,Nojima, Susumu,Mizuno, Noritaka
-
supporting information; scheme or table
p. 12062 - 12066
(2012/02/03)
-
- (5R,7R)-5-Methylheptadecan-7-ol: A novel sex pheromone component produced by a female lichen moth, Miltochrista calamina, in the family Arctiidae
-
A methyl-branched heptadecanol was found in the pheromone gland extract of a female lichen moth, Miltochrista calamina (Arctiidae, Lithosiinae). GC-MS analyses of the alcohol and a hydrocarbon derived from it by subsequent treatments with methanesulfonyl chloride and LiAlD4 in microscale reactions indicated 5-methylheptadecan-7-ol (1) as one possible structure. The four stereoisomers of 1 in a ratio of 4:4:1:1 were prepared from (S)-b-citronellol with 60% ee, and were separated by a combination of achiral and chiral HPLC columns. The absolute configuration of each isomer was determined by the comparison with the chromatographic behaviors of other samples synthesized by a different scheme, which applied the Jacobsen hydrolytic kinetic resolution of racemic 1,2-epoxydodecane to fix the configuration of the 7-hydroxy group. Only the (5R,7R)-isomer attracted male moths; thus, we concluded that M. calamina females secrete (5R,7R)-1 as a sex pheromone, indicating a new chemical class of lepidopteran female sex pheromones.
- Yamakawa, Rei,Kiyota, Ryutaro,Taguri, Tomonori,Ando, Tetsu
-
scheme or table
p. 5808 - 5811
(2011/12/14)
-
- Selective oxidation of terminal aryl and aliphatic alkenes to aldehydes catalyzed by iron(iii) porphyrins with triflate as a counter anion
-
[Fe(Por)CF3SO3] (Por = porphyrin dianion) can efficiently catalyze selective oxidation of terminal aryl alkenes and aliphatic alkenes to aldehydes in good to high yields under mild conditions.
- Chen, Guo-Qiang,Xu, Zhen-Jiang,Zhou, Cong-Ying,Che, Chi-Ming
-
supporting information; experimental part
p. 10963 - 10965
(2011/11/06)
-
- Synthesis and characterization of supported heteropolymolybdate nanoparticles between silicate layers of Bentonite with enhanced catalytic activity for epoxidation of alkenes
-
A new heterogeneous catalyst (PVMo/Bentonite) consisting of vanadium substituted heteropolymolybdate with Keggin-type structure Na 5[PV2Mo10O40]·14H 2O (PVMo) supported between silicate layers of bentonite has been synthesized by impregnation method and characterized using X-ray diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy and elemental analysis. X-ray diffraction and scanning electron microscopy analysis indicated that PVMo was finely dispersed into layers of bentonite as support. The PVMo/Bentonite used as an efficient heterogeneous catalyst for epoxidation of alkenes. Various cyclic and linear alkenes were oxidized into the corresponding epoxides in high yields and selectivity with 30% aqueous H2O 2. The catalyst was reused several times, without observable loss of activity and selectivity. The obtained results showed that the catalytic activity of the PVMo/Bentonite was higher than that of pure heteropolyanion (PVMo).
- Salavati, Hossein,Rasouli, Nahid
-
scheme or table
p. 1853 - 1859
(2011/11/05)
-
- Zirconia-supported Keggin phosphomolybdovanadate nanocomposite: A heterogeneous and reusable catalyst for alkene epoxidation under thermal and ultrasonic irradiation conditions
-
Keggin phosphomolybdovanadate, PVMo, was supported on a zirconia matrix by the wet impregnation method. The phase and chemical structure, optical absorption, surface physicochemical properties and morphology of PVMo-ZrO 2 composite were studied by X-ray diffraction (XRD) technique, FT-IR and diffuse reflectance UV-vis spectroscopic (DR UV-vis) methods, and scanning electron microscopy (SEM), which indicated that the primary Keggin structure has remained intact after formation of the composite. Moreover, the obtained nanocomposite was used as an efficient catalyst of olefins under reflux and ultrasonic irradiation conditions. The catalyst was reused several times, without observable loss of activity and selectivity. Indeed, the catalytic activity of the PVMo-ZrO2 was compared with pure Keggin phosphomolybdovanadate.
- Salavati, Hossein,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
-
experimental part
p. 588 - 596
(2012/05/20)
-
- OXIDIZING AGENT COMPOSITION FOR EPOXIDATION AND OXIDATION METHOD THEREOF
-
Disclosed is a method for epoxidizing olefins, which enables an epoxy compound containing no halogen atom with high yield. Specifically disclosed is an oxidizing agent composition for epoxidation of olefins, which is characterized by containing peroxide which exhibits basicity when dissolved in water and an acid anhydride.
- -
-
Page/Page column 6
(2010/06/17)
-
- "click" tetradentate ligands
-
A series of triazole-based N4 tetradenate ligands 1a-d are efficiently synthesized using CuI-catalyzed azide-alkyne "click" strategy and are readily coordinated to many metal ions (e.g. MnII, NiII, ZnII and FeII). The X-ray structures of the resultant metal-complexes (4a-d, 5a, 6a and 7a) reveal an octahedral mononuclear structure with two co-ligands bonded in cis sites and the two triazoles as nitrogen donors to the metal center. The MnII-complexes (4a-d) show efficient catalytic activities in the epoxidation of various aliphatic terminal olefins with peracetic acid, and feature with low catalyst loading, fast conversion and high yields. The Royal Society of Chemistry 2010.
- Hao, Erhong,Wang, Zhaoyun,Jiao, Lijuan,Wang, Shaowu
-
experimental part
p. 2660 - 2666
(2010/06/13)
-
- Synthesis and catalytic epoxidation potential of oxodiperoxo molybdenum(VI) complexes with 2-hydroxybenzohydroxamate and 2-hydroxybenzoate: The crystal structure of PPh4[MoO(O2)2(HBA)]
-
(PPh4)2[MoO(O2)2(SHAH)] ·H2O and PPh4[MoO-(O2)2(HBA)] (SHAH3 = 2-hydroxybenzohydroxamic acid and HBAH = 2-hydroxybenzoic acid) have been synthesized and characterized by physico-chemical and spectroscopic methods. In addition, the second complex has been structurally characterized by single-crystal X-ray diffraction analysis. We have compared the catalytic activities of these two new complexes, together with the previously reported PPh4[MoO(O2)2(BZ)] (BZH = benzoic acid), with respect to the epoxidation of alkenes. The hydroxamate complex is the most efficient catalyst among the three complexes, showing excellent catalytic activity for the substrates cyclohexene, cyclooctene, cinnamyl alcohol, pent-4-en-1-ol and hex-1-ene. Springer Science+Business Media B.V. 2010.
- Gharah, Narottam,Chattopadhyay, Basab,Maiti, Swarup K.,Mukherjee, Monika
-
experimental part
p. 531 - 539
(2011/11/12)
-
- Novel polyaniline supported cobalt catalyzed aerobic oxidation of unsaturated organic compounds
-
The oxidation of organic compounds with carbon-carbon double bond with molecular oxygen under atmospheric pressure in the presence of new polyaniline supported catalyst 1 has been studied. This catalyst turned out to be efficient and selective for oxidation of some unsaturated organic compounds. Oxidation of alkenes, cycloalkenes and terpenes give corresponding epoxy derivatives, whereas organic compounds with carbon carbon double bond in benzylic position give ketones as a main product. Taylor & Francis Group, LLC.
- Pielichowski, Jan,Kowalski, Grzegorz
-
experimental part
p. 105 - 111
(2011/08/03)
-
- Epoxidation of olefins by β-bromoalkoxydimethylsulfonium ylides
-
Olefins can be converted to their respective epoxides in a one-pot procedure by dissolving the olefin in anhydrous DMSO, adding NBS to the reaction mixture to generate a β-bromoalkoxydimethylsulfonium ylide, and then adding DBU to the reaction mixture. A large variety of alkenes were successfully epoxi-dized with yields largely dependent on the structure of the alkene. Most importantly, the facial selectivity of this one-pot process is the opposite of that observed when using traditional epoxidizing reagents. Electron-poor alkenes are not epoxidized under these conditions.
- Majetich, George,Shimkus, Joel,Li, Yang
-
supporting information; experimental part
p. 6830 - 6834
(2011/03/18)
-
- A flexible nonporous heterogeneous catalyst for size-selective oxidation through a bottom-up approach
-
Size does matter: The nonporous tetra-n-butylammonium salt of silicodecatungstate, synthesized through a bottom-up approach, heterogeneously catalyzes the size-selective oxidation of various organic compounds, including olefins, sulfides, and organosilanes, with aqueous H2O2 in ethyl acetate. The catalyst can be easily separated by filtration and reused several times with retention of high catalytic activity. Copyright
- Mizuno, Noritaka,Uchida, Sayaka,Kamata, Keigo,Ishimoto, Ryo,Nojima, Susumu,Yonehara, Koji,Sumida, Yasutaka
-
supporting information; experimental part
p. 9972 - 9976
(2011/03/18)
-
- Regioselective epoxidation of different types of double bonds over large-pore titanium silicate Ti-β
-
Regioselective epoxidation of different types of double bonds located within the cyclic and acyclic parts of bulky olefins has been investigated using large-pore titanium silicate Ti-β in the presence of dilute aqueous H 2O2 as oxidant under mild liquid-phase conditions. Our experimental results revealed that side-chain vinylic double bonds are selectively epoxidized than those in the cyclohexene-ring. The epoxidation tendency of various bulky olefins with different positional and/or geometric isomers over Ti-β follows the order: terminal -CC- > ring -CC- ≈ bicyclic ring -CC- > allylic C - H bond. Unlike 4-vinyl-1-cyclohexene, epoxidation of an equimolar mixture of cyclohexene and 1-hexene under identical conditions using Ti-β exhibits completely different selectivity and product distributions. Steric factor and accessibility of reactants to active Ti-sites are responsible for the observed regioselectivity of bulky alkenes.
- Sasidharan, Manickam,Bhaumik, Asim
-
experimental part
p. 60 - 67
(2010/12/18)
-
- Sonocatalytic oxidation of olefins catalyzed by heteropolyanion-montmorillonite nanocomposite
-
A Keggin-type heteropolyanion compound (HPO) was doped within the montmorillonite (MMT) structure by impregnation method. The synthesized catalyst was characterized by FT-IR, XRD, UV-vis, CV, SEM and elemental analysis. Based on chemical adsorption between HPO, and hydroxyl surface groups, HPOs nanoparticles were successfully located on the MMT. Moreover, the obtained nanocomposite was found as an efficient catalyst for oxidation of hydrocarbons under reflux and ultrasonic irradiation conditions.
- Salavati, Hossein,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
-
experimental part
p. 145 - 152
(2010/11/18)
-
- Sonocatalytic epoxidation of alkenes by vanadium-containing polyphosphomolybdate immobilized on multi-wall carbon nanotubes
-
A Keggin type polyoxometalate (POM) has been immobilized in the unique network structure of multi-wall carbon nanotubes (CNTs). The vanadium-containing polyphosphomolybdate (PVMo) supported on CNTs, which was prepared by a one-step solid-state reaction, was characterized by FT-IR, XRD, SEM and elemental analyses. These uniform nanoparticles have an average size 20-30 nm. Furthermore, due to the chemical interaction between PVMo and carboxylic acid groups, PVMo nanoparticles were successfully immobilized on the CNTs. Moreover, the obtained composite was found as an efficient catalyst for oxidation of hydrocarbons under reflux and ultrasonic irradiation (US) conditions.
- Salavati, Hossein,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
-
experimental part
p. 453 - 459
(2010/12/25)
-
- Epoxidation of alkenes using HOF·MeCN by a continuous flow process
-
Continuous flow methodology is described which allows the in situ generation of the highly effective oxidising agent HOF·MeCN from fluorine and wet acetonitrile and immediate reaction with alkenes to afford epoxides in high yield. The HOF·MeCN continuous flow oxidising system provides an environmentally benign process that is suitable for large scale synthesis and is atom efficient, because the only by-product is hydrogen fluoride which, in principle, could be recycled to produce fluorine by electrolysis. Crown Copyright
- McPake, Christopher B.,Murray, Christopher B.,Sandford, Graham
-
experimental part
p. 1674 - 1676
(2009/09/05)
-
- Oxidoperoxidotungsten(VI) complexes with secondary hydroxamic acids: Synthesis, structure and catalytic uses in highly efficient, selective and ecologically benign oxidation of olefins, alcohols, sulfides and amines with H2O2 as a terminal oxidant
-
The reaction of a solution of freshly precipitated WO3 in H 2O2 separately with the secondary hydroxamic acids N-benzoyl-N-phenylhydroxamic acid (BPHAH), N-benzoyl-Northo-tolylhydroxamic acid (BOTHAH), N-benzoyl-N-meta-tolylhydroxamic acid (BMTHAH), N-benzoyl-N-para- tolyl-hydroxamic acid (BPTHAH) and N-cinnamyl-N-phenylhy-droxamic acid (CPHAH) afforded [WO(O2)(BPHA)2] (1), [WO(O2)(BOTHA) 2] (2), [WO(O2)(BMTHA)2] (3), [WO(O 2)-(BPTHA)2] (4) and [WO(O2)(CPHA)2] (5), respectively. Aqueous tungstate solution, on reaction with all these hydroxamic acids, produced [W(O)2(hydroxamato)2] (6). The complexes show excellent catalytic functions in the oxidation of (a) olefins at room temperature in the presence of NaHCO3 as promoter, (b) alcohols, sulfides and amines, at reflux, with H2O2 as a terminal oxidant, yielding a high turnover number (TON), the highest being for olefin-to-epoxide conversion. An attempt to synthesize peroxide-rich complexes of the type PPh4[WO(O2)2(hydroxamato)] (7), for example PPh4[WO-(O2)2BMTHA] (7C), resulted in the isolation of PPh4[WO-(O2)2(C 6H5COO)] (8), which was probably obtained by the hydrolysis of coordinated BMTHA. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Maiti, Swarup K.,Dinda, Subhajit,Banerjee, Surajit,Mukherjee, Alok K.,Bhattacharyya, Ramgopal
-
experimental part
p. 2038 - 2051
(2009/03/11)
-
- A simple and effective catalytic system for epoxidation of aliphatic terminal alkenes with manganese(II) as the catalyst
-
A simple catalytic system that uses commercially available manganese(II) Perchlorate as the catalyst and peracetic acid as the oxidant is found to be very effective in the epoxidation of aliphatic terminal alkenes with high product selectivity at ambient temperature. Many terminal alkenes are epoxidised efficiently on a gram scale in less than an hour to give excellent yields of isolated product (>90%) of epoxides in high purity. Kinetic studies with some C9-alkenes show that the catalytic system is more efficient in epoxidising terminal alkenes than internal alkenes, which is contrary to most commonly known epoxidation systems. The reaction rate for epoxidation decreases in the order: 1-nonene>cis-3-nonene> trans-3-nonene. ESI-MS and EPR spectroscopic studies suggest that the active form of the catalyst is a high-valent oligonuclear manganese species, which probably functions as the oxygen atomtransfer agent in the epoxidation reaction.
- Ho, Kam-Piu,Wong, Wing-Leung,Lam, Kin-Ming,Lai, Cheuk-Piu,Chan, Tak Hang,Wong, Kwok-Yin
-
experimental part
p. 7988 - 7996
(2009/11/30)
-