- A new halide-free efficient reaction-controlled phase-transfer catalyst based on silicotungstate of [(C18H37)2(CH 3)2N]3[SiO4H(WO5) 3] for olefin epoxidation, oxidation of sulfides and alcohols with hydrogen peroxide
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A new reaction-controlled phase-transfer catalyst based on silicotungstate of [(C18H37)2(CH3) 2N]3[SiO4H(WO5)3] for oxidation of hydrocarbons is developed. The catalyst is a new heteropoly compound with silicon as heteroatom, which is different to the previously reported reaction-controlled phase transfer catalysts that were composed of quaternary ammonium heteropolyoxotungstates of [π-C5H 5N(CH2)15CH3]3[PW 4O16] and [π-C5H5N(CH 2)15CH3]3[PW4O 32] with phosphorus as heteroatom. The oxidation of various alkenes (such as linear terminal olefins, internal olefins, cyclic olefins and unactivated alkenes) to epoxides, sulfides to sulfoxides and sulfones, alcohols to carbonyl compounds, are successfully catalyzed by this recyclable and environmentally benign catalyst using H2O2 as oxidant and ethyl acetate as solvent. This catalyst is not only capable of catalyzing homogeneous oxidation of organic substrates with unique reaction-controlled phase-transfer character, but also avoids the use of toxic solvents. The catalyst could be easily recovered and reused after reaction, and the epoxidation of cyclohexene was performed twenty times without obvious loss in activity. The fresh catalyst and the used one were characterized by ICP, IR, UV-vis, 29Si MAS NMR and 183W NMR in detail. the Partner Organisations 2014.
- Ma, Baochun,Zhao, Wei,Zhang, Fuming,Zhang, Yingshuai,Wu, Songyun,Ding, Yong
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p. 32054 - 32062
(2014/08/18)
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- Organocatalyzed epoxidation of alkenes in continuous flow using a multi-jet oscillating disk reactor
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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
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scheme or table
p. 261 - 265
(2012/05/05)
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- Synthesis of epoxides catalyzed by a halide-free reaction-controlled phase-transfer catalytic system: [(CH3(CH2) 17)2N(CH3)2]3[PW 4O32]/H2O2/Dioxan/Olefin
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The epoxidation of alkenes was successfully catalyzed by a recyclable catalytic system: [(CH3(CH2)17) 2N(CH3)2]3[PW4O 32]/H2O2/dioxan/olefin. This new catalytic system is not only capable of catalyzing homogeneous epoxidation of alkenes with a unique reaction-controlled phase-transfer character, but also avoids the use of chlorinated solvents. The reactions were conducted in a biphasic mixture of aqueous H2O2/dioxan, and many kinds of alkenes could be efficiently converted to the corresponding epoxides in high yields. Both new and used [(CH3(CH2)17)2N(CH 3)2]3[PW4O32] catalyst was characterized by 31P magic angle spin NMR, and IR. CSIRO 2009.
- Ding, Yong,Ma, Baochun,Tong, Dejie,Hua, Hui,Zhao, Wei
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experimental part
p. 739 - 746
(2010/02/16)
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- Substrate-induced diastereoselectivity in the dimethyldioxirane epoxidation of simple alkenes and dienes
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Various alkenes and dienes, such as (R)- or (S)-limonene 2, 2-carene 6, 3-carene 8, (R)-α-pinene 10, (S)-α-pinene 12, and endo-dicyclopentadiene 14 were transformed into the corresponding mono- and bis-epoxides by epoxidation with dimethyldioxirane (as an acetone solution). The selectivity observed in these epoxidations is explained by the assumption of hydrogen bonding between bridge protons and the dioxirane.
- Asouti,Hadjiarapoglou
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p. 1847 - 1850
(2007/10/03)
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- Regioselective and diastereoselective dimethyldioxirane epoxidation of substituted norbornenes and hexamethyl Dewar benzene
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Various substituted norbornenes, such as endo-dicyclopentadiene 1, exo- dicyclopentadiene 5, 5-methylenebicyclo[2.2.1]hept-2-ene 8 and hexamethyl Dewar benzene 10 were transformed into the corresponding mono- and bis- epoxides by epoxidation with dimethyldioxirane (as an acetone solution).
- Asouti, Amalia,Hadjiarapoglou, Lazaros P.
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p. 539 - 542
(2007/10/03)
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- Oxidation of Organic Substrates by Molecular Oxygen/Aldehyde/ Heteropolyoxometalate System
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Heteropolyoxometalate-catalyzed oxidations of organic compounds such as olefins and cyclic ketones with molecular oxygen in the presence of an aldehyde were examined.Olefins were epoxidized with dioxygen in the presence of 2 equiv of 2-methylpropanal under the influence of a catalytic amount of the mixed heteropolyoxometalate NPV6Mo6 (3) to give the corresponding epoxides in moderate to good yields.This catalytic oxidation method was also applied to the epoxidation of allylic and homoallylic alcohols.In the absence of olefins, the aldehydes were efficiently convertedinto the corresponding carboxylic acids.In addition, the Baeyer-Villiger oxidation of cyclic ketones was accomplished by using benzaldehyde instead of 2-methylpropanal as the aldehyde.
- Hamamoto, Masatoshi,Nakayama, Kouichi,Nishiyama, Yutaka,Ishii, Yasutaka
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p. 6421 - 6425
(2007/10/02)
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- SODIUM PERBORATE OXIDATIONS OF CYCLIC AND ACYCLIC ALKENES TO OXIRANES OR VICINAL ACETOXY ALCOHOLS
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Under different reaction conditions, sodium perborate/acetic anhydride oxidizes alkenes into oxiranes or vicinal acetoxy alcohols in good yields.
- Xie, Gaoyang,Xu, Linxiao,Hu, Jun,Ma, Shiming,Hou, Wei,Tao, Fenggang
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p. 2967 - 2968
(2007/10/02)
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- REACTION OF CYCLIC EPOXIDE COMPOUNDS WITH TRIPHENYLPHOSPHINE
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Significant differences were found in the reactivity of a series of epoxides of cycloalkenes and methylenecycloalkanes and diepoxides in reaction with triphenylphosphine, depending both on the steric effects of the cyclic fragments and on their strain.The level of the strain can be judged indirectly from the chemical shifts of the 1H and 13C nuclei and the spin-spin coupling constants of the C-H bonds in the epoxide ring.
- Kas'yan, L. I.,Stepanova, N. V.,Galafeeva, M. F.,Boldeskul, I. E.,Trachevskii, V. V.,Zefirov, N. S.
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p. 109 - 112
(2007/10/02)
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- Regioselective Oxidation of Carbon-Carbon Double Bond of endo-Dicyclopentadiene
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endo-9-Oxatetracyclo2.6.08.10>undec-3-ene (2) has been selectively prepared by the oxidation of endo-dicyclopentadiene (1) with chromium trioxide in acetic acid.On the other hand oxidation of 1 by pyridinium chlorochromate furnishes a 1 : 1 mixture of α-chloroketones (3 and 4) in high yield.A plausible mechanism is advanced to explain the formation of 3 and 4.
- Pandey, Paras N.,Purkayastha, Makhan L.
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p. 717 - 719
(2007/10/02)
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- Dicyclopentadiene Oxidation. IV. Oxidation of 4,5- and 8,9-Dihydro-dicyclopentadiene
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A mixture of exo- and endo-4,5-dihydro-dicyclopentadiene 5 and also pure endo-8,9-dihydro-dicyclopentadiene 7 and pure exo-dicyclopentadiene 10 was oxidized in the absence and in the presence of catalysts.The compounds containing the norbornene structure mainly gave the corresponding exo-epoxides.No catalytic effects were observed in the formation of these norbornene epoxides.Compound 7 containing only the cyclopentene structure mainly yielded the corresponding hydroperoxide 9.In this case a catalytic effect of epoxidation catalysts was observed : in the presence of such catalysts the epoxide was increased. The results obtained prove the mechanism of dicyclopentadiene oxidation proposed by us.
- Schnurpfeil, D.,Lauterbach, G.
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p. 121 - 128
(2007/10/02)
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- Dicyclopentadiene Oxidation. II. Catalyzed Liquid-Phase Oxidation of Dicyclopentadiene
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The liquid-phase oxidation of dicyclopentadiene 1 by molecular oxygen was studied in the presence of MoO2(acac)2 as a typical epoxidation catalyst.The yield of the mono-epoxides 2 and 3 is increased to 56.4 percent (uncatalyzed reaction: 43.6 percent).The ratio of the two mono-epoxides is decreased to 2/3 = 2.6 in relation to the uncatalyzed reaction 2/3 = 7.1).The influence of temperature, conversion and solvents is described.The bisepoxide 4 is formed at lower conversions than in the uncatalyzed reaction.But also at higher conversion of 1 not more than 10 percent of the bisepoxide 4 is formed.
- Schnurpfeil, D.
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p. 842 - 847
(2007/10/02)
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- Dicyclopentadiene Oxidation I. Uncatalyzed Liquid-Phase Oxidation of Dicyclopentadiene
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Dicyclopentadiene is oxidized by molecular oxygen to a mixture of the monoepoxides 2 and 3.The identification of the epoxides 2, 3 and 4 was executed with authentic samples prepared by epoxidation with peracetic acid or with tert-butylhydroperoxide in the presence of MoO2(acac)2.The main product is the substituted norbornene oxide 2.Allylic oxidation is also observed.Remarkable amounts of hydroperoxides can be determined iodometrically.The formation of allylic oxidation products 7, 8, 9 and 10 was proved by GC-MS-analysis.It is shown that in the uncatalyzed liquid phase oxidation of dicyclopentadiene no more than 50 percent of epoxides are formed.The bisepoxide 4 was found in small amounts only at higher conversions of the dicyclopentadiene.
- Schnurpfeil, D.
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p. 481 - 488
(2007/10/02)
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