- Oxidation of alkenes by oxodiperoxomolybdenum: Trialkyl(aryl)phosphine oxide complexes
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Catalytic amounts of short-chain (2-4 carbons) trialkylphosphine oxide ligands and MoO5 have been shown to efficiently convert di- and higher substituted alkenes to the corresponding epoxides using a biphasic system with either 30% hydrogen peroxide or 70% TBHP acting as the stoichiometric oxidant. Georg Thieme Verlag Stuttgart.
- Kiraz, Christine I. Altinis,Mora, Luis,Jimenez, Leslie S.
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- Highly selective synthesis of cyclododecanone over mesostructured VSBA-15 catalysts
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Highly ordered VSBA-15 mesoporous catalysts have been synthesized under pH-adjusting direct hydrothermal (pH-aDH) method using vanadyl sulphate hydrate and Pluronic P123 as the sources of vanadium and template, respectively. The mesoporous catalysts characterized by sophisticated instrumental techniques, viz. ICP-AES, XRD, N2 adsorption, ESR, UV-vis DRS, 51V MAS NMR, 29Si MAS NMR and TEM show their two-dimensional mesostructures with tetrahedral vanadium species on the silica surface. The well ordered VSBA-15 catalysts have been used in the oxidation of cyclododecane (CDD) with hydrogen peroxide (H2O2, 30%) to find their catalytic activities. The regenerated VSBA-15 catalysts have been examined to find their catalytic stabilities. VSBA-15(5) catalyst has been washed with ammonium acetate solution to investigate the leaching of vanadium species in the framework of silica network of SBA-15, and the catalytic activity of washed VSBA-15(5) has also been examined in the catalytic reactions. Moreover, the hydrothermally stable VSBA-15(5) catalyst has also been examined in the catalytic reaction to find the effect of its catalytic activity. Additionally, the influences of various reaction parameters such as temperature, time, ratios of reactant and solvents on the oxidation of CDD have been investigated. Based on the catalytic results, VSBA-15(5) catalyst is found to be a highly active, recyclable and promising heterogeneous catalyst for selective synthesis of cyclododecanone (CDDO).
- Selvaraj,Park
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- Dendritic phosphonates and the in situ assembly of polyperoxophosphotungstates: Synthesis and catalytic epoxidation of alkenes with hydrogen peroxide
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First and second-generation rigid dendrimers based on polyphenylated tetrahedral adamantane cores with four or sixteen peripheral phosphonate moieties, PD1 and PD2, respectively, were synthesized and characterized. Further reaction of the dendritic phosphonates with tungstic acid in the presence of hydrogen peroxide led to the stepwise in situ formation of mono- and dinuclear phosphoperoxotungstates. These assemblies were effective catalysts for the epoxidation of alkenes in an aqueous acetonitrile solvent.
- Vasylyev, Maxym V.,Astruc, Didier,Neumann, Ronny
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- SYNTHESIS OF 1,2-CYCLOALKANEDIOLS BY INTRAMOLECULAR TITANIUM-INDUCED PINACOL COUPLING
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Seven representative 1,2-cycloalkanediols of ring size 6-14 were prepared in high yield by titanium-induced pinacol coupling of dialdehydes.Cis stereochemistry predominated in six- and eight-membered rings, but trans products were formed in ring sizes ten and above.
- McMurry, John E.,Rico, Joseph G.
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p. 1169 - 1172
(2007/10/02)
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- Permanganate Ion Oxidations. 19. Hexadecyltrimethylammonium Permanganate Oxidation of Cycloalkenes
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The kinetics of hexadecyltrimethylammonium permanganate (cetyltrimethylammonium permanganate, CTAP) oxidation of cycloalkenes in dichloromethane have been studied.The relative rates of oxidation versus 13C NMR chemical shifts, vertical ionization potentials, and strain energies are discussed.A comparison of the relative rate of permanganate ion oxidation with the relative rates of addition of other reagents to carbon-carbon double bonds suggests that it may act as a 1,3-dipole.
- Freeman, Fillmore,Kappos, John C.
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p. 2730 - 2734
(2007/10/02)
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