1192-22-9Relevant articles and documents
Metalation and DFT studies of metal organic frameworks UiO-66(Zr) with vanadium chloride as allyl alcohol epoxidation catalyst
Geravand, Elham,Farzaneh, Faezeh,Ghiasi, Mina
, (2019)
UiO-66(Zr)-V as metal organic framework was prepared by metalation of the UiO-66(Zr) nodes with VCl3. The characterization of the prepared catalyst was carried out using XRD, EDX, FT IR, BET, ICP, Raman, DRS, SEM and XPS techniques. The density functional theory (DFT) was used in order to find the most stable position of the vanadium of metallated UiO-66(Zr). It was found that UiO-66(Zr)-V has been generated via metalation of V(V) ions with two OH groups of Zr-based nodes. The XPS results confirmed DFT studies. The catalytic activity of UiO-66(Zr)-V for epoxidation of some allyl alcohols such as trans-2-hexene-1-ol, geraniol, 1-octene-3-ol and 3-methyl-2-buten-1-ol with 46–97% conversions and 100% selectivity is considerable.
Kinetics of the epoxidation of geraniol and model systems by dimethyldioxirane
Baumstark,Franklin,Vasquez,Crow
, p. 117 - 124 (2004)
The mono-epoxidation of geraniol by dimethyldioxirane was carried out in various solvents. In all cases, the product ratios for the 2,3 and 6,7 mono-epoxides were in agreement with literature values. Kinetic studies were carried out at 23 °C in the following dried solvent systems: acetone (k 2 = 1.49 M-1s-1), carbon tetrachloride/acetone (9/1, k2=2.19 M-1s-1), and methanol/acetone (9/1, k2 = 17 M-1s-1). Individual k2 values were calculated for epoxidation of the 2,3 and 6,7 positions in geraniol. The non-conjugated diene system was modeled employing two simple independent alkenes: 2-methyl-2-pentene and 3-methyl-2-buten-1-ol by determining the respective k2 values for epoxidation in various solvents. The kinetic results for each independent alkene showed that the relative reactivity of the two epoxidation sites in geraniol as a function of solvent was not simply a summation of the independent alkene systems.
Selective Epoxidation of Olefins by Oxo(V) Alkylpreoxides. On the Mechanism of the Halcon Epoxidation Process
Mimoun, Hubert,Mignard, Michel,Brechot, Philippe,Saussine, Lucien
, p. 3711 - 3718 (1986)
Novel vanadium(V) alkylperoxy complexes with the general formula VO(OOR)(R'-OPhsal-R'') (II) were synthesized and characterized by physicochemical methods.These complexes most probably have a pentagonal pyramidal structure, with an axial vanadyl group and, in the pentagonal plane, three positions occupied by the Schiff base planar ligand and two positions occupied by a bidendate alkylperoxy group which is presumably weakly coordinatively bonded to the metal by the alkoxy oxygen atom.These complexes are very effective reagents for the selective transformation of olefins into epoxides, with yields ranging from 40percent for 1-octene to 98percent for tetramethylethylene.The reactivity of olefins is sensitive to steric hindrance and increases with the olefin nucleophilicity.The epoxidation of olefins by complexes II is steroselective, inhibited by water, alcohols, and basic ligands or solvents, and accelerated in polar nondonor solvents.Kinetic studies showed that the olefin coordinates to the metal prior to the decomposition of the metal-olefin complex in the rate-determining step.Competitive epoxidation of several olefins vs. cyclohexene showed that the more strongly coordinated olefins exert an inhibiting effect on the epoxidation of the less strongly coordinated ones.These data, which are similar to those of the Halcon catalytic epoxidation process, are consistent with a pseudocyclic peroxy metalation mechanism.
Selective catalytic oxidation of alcohols, aldehydes, alkanes and alkenes employing manganese catalysts and hydrogen peroxide
Saisaha, Pattama,Buettner, Lea,Van Der Meer, Margarethe,Hage, Ronald,Feringa, Ben L.,Browne, Wesley R.,De Boer, Johannes W.
supporting information, p. 2591 - 2603 (2013/10/21)
The manganese-containing catalytic system [MnIV,IV 2O3(tmtacn)2]2+ (1)/carboxylic acid (where tmtacn=N,N′,N′′-trimethyl-1,4,7-triazacyclononane), initially identified for the cis-dihydroxylation and epoxidation of alkenes, is applied for a wide range of oxidative transformations, including oxidation of alkanes, alcohols and aldehydes employing H2O2 as oxidant. The substrate classes examined include primary and secondary aliphatic and aromatic alcohols, aldehydes, and alkenes. The emphasis is not primarily on identifying optimum conditions for each individual substrate, but understanding the various factors that affect the reactivity of the Mn-tmtacn catalytic system and to explore which functional groups are oxidised preferentially. This catalytic system, of which the reactivity can be tuned by variation of the carboxylato ligands of the in situ formed [MnIII,III 2(O)(RCO2)2(tmtacn)2]2+ dimers, employs H2O2 in a highly atom efficient manner. In addition, several substrates containing more than one oxidation sensitive group could be oxidised selectively, in certain cases even in the absence of protecting groups. Copyright
Efficient epoxidation of electron-deficient alkenes with hydrogen peroxide catalyzed by [γ-PW10O38V2(μ-OH) 2]3-
Kamata, Keigo,Sugahara, Kosei,Yonehara, Kazuhiro,Ishimoto, Ryo,Mizuno, Noritaka
scheme or table, p. 7549 - 7559 (2011/08/03)
A divanadium-substituted phosphotungstate, [γ-PW10O 38V2(μ-OH)2]3- (I), showed the highest catalytic activity for the H2O2-based epoxidation of allyl acetate among vanadium and tungsten complexes with a turnover number of 210. In the presence of I, various kinds of electron-deficient alkenes with acetate, ether, carbonyl, and chloro groups at the allylic positions could chemoselectively be oxidized to the corresponding epoxides in high yields with only an equimolar amount of H2O2 with respect to the substrates. Even acrylonitrile and methacrylonitrile could be epoxidized without formation of the corresponding amides. In addition, I could rapidly (min) catalyze epoxidation of various kinds of terminal, internal, and cyclic alkenes with H;bsubesubbsubesub& under the stoichiometric conditions. The mechanistic, spectroscopic, and kinetic studies showed that the I-catalyzed epoxidation consists of the following three steps: 1) The reaction of I with H;bsubesubbsubesub& leads to reversible formation of a hydroperoxo species [I;circbsubesubbsubesubbsubesubcirccircbsupesup& (II), 2) the successive dehydration of II forms an active oxygen species with a peroxo group [ 2:2-O2)]3- (III), and 3) III reacts with alkene to form the corresponding epoxide. The kinetic studies showed that the present epoxidation proceeds via III. Catalytic activities of divanadium-substituted polyoxotungstates for epoxidation with H 2O2 were dependent on the different kinds of the heteroatoms (i.e., Si or P) in the catalyst and I was more active than [γ-SiW10O38V2(μ-OH)2] 4-. On the basis of the kinetic, spectroscopic, and computational results, including those of [γ-SiW10O38V 2(μ-OH)2]4-, the acidity of the hydroperoxo species in II would play an important role in the dehydration reactivity (i.e., k3). The largest k3 value of I leads to a significant increase in the catalytic activity of I under the more concentrated conditions. Copyright
