13107-39-6Relevant articles and documents
Mononuclear Nonheme Iron(III)-Iodosylarene and High-Valent Iron-Oxo Complexes in Olefin Epoxidation Reactions
Wang, Bin,Lee, Yong-Min,Seo, Mi Sook,Nam, Wonwoo
, p. 11740 - 11744 (2015)
High-spin iron(III)-iodosylarene complexes are highly reactive in the epoxidation of olefins, in which epoxides are formed as the major products with high stereospecificity and enantioselectivity. The reactivity of the iron(III)-iodosylarene intermediates is much greater than that of the corresponding iron(IV)-oxo complex in these reactions. The iron(III)-iodosylarene species - not high-valent iron(IV)-oxo and iron(V)-oxo species - are also shown to be the active oxidants in catalytic olefin epoxidation reactions. The present results are discussed in light of the long-standing controversy on the one oxidant versus multiple oxidants hypothesis in oxidation reactions. On active duty: High-spin iron(III)-iodosylarene complexes epoxidize olefins with high stereospecificity and enantioselectivity. The iron(III)-iodosylarene species, not high-valent iron(IV)- and iron(V)-oxo species, are the active oxidants in catalytic olefin epoxidation reactions. The present results resolve the long-standing controversy on the one oxidant versus multiple oxidants hypothesis in oxidation reactions.
Immobilization of a molybdenum complex on the surface of magnetic nanoparticles for the catalytic epoxidation of olefins
Zare, Maryam,Moradi-Shoeili, Zeinab,Bagherzadeh, Mojtaba,Akbayrak, Serdar,?zkar, Saim
, p. 1580 - 1586 (2016)
Novel organic-inorganic hybrid heterogeneous nanocatalysts were obtained by covalent anchoring of a molybdenum(vi) complex of salicylidene 2-picoloyl hydrazine, MoO2(sal-phz)(CH3OH), (1) on the surface of magnetic nanoparticles funct
Hydrocarbon oxidation by β-halogenated dioxoruthenium(vi) porphyrin complexes: Effect of reduction potential (RuVI/V) and C-H bond-dissociation energy on rate constants
Che, Chi-Ming,Zhang, Jun-Long,Zhang, Rui,Huang, Jie-Sheng,Lai, Tat-Shing,Tsui, Wai-Man,Zhou, Xiang-Ge,Zhou, Zhong-Yuan,Zhu, Nianyong,Chang, Chi Kwong
, p. 7040 - 7053 (2005)
β-Halogenated dioxoruthenium(VI) porphyrin complexes [Ru VI-(F28-tpp)O2] [F28-tpp = 2,3,7,8,12,13, 17,18-octafluoro-5,10,15,20-tetrakis-(pentafluorophenyl)porphyrinato(2-)] and [RuVI(β-Br8-tmp)O2] [β-Br 8-tmp = 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(2,4,6-trimethylphenyl) porphyrinato(2-)] were prepared from reactions of [RuII(por)(CO)] [por = por-phyrinato(2-)] with m-chloroperoxybenzoic acid in CH 2Cl2. Reactions of [RuVI(por)O2] with excess PPh3 in CH2Cl2 gave [Ru II(F20tpp)(PPh3)2] [F 20)-tpp = 5,10,15,20-tetrakis(pentafluo-rophenyl)porphyrinato(2-)] and [RuII-(F28-tpp)(PPh3)2]. The structures of [RuII(por)(CO)(H2O)] and [Ru II(por)-(PPh3)2] (por = F20-tpp, F28-tpp) were determined by X-ray crystallography, revealing the effect of β-fluorination of the porphyrin ligand on the coordination of axial ligands to ruthenium atom. The X-ray crystal structure of [Ru VI(F20-tpp)O2] shows a Ru=O bond length of 1.718(3) A. Electrochemical reduction of [RuVI(por)O 2] (RuVI to RuV) is irreversible or quasi-reversible, with the Ep.c(RuVI/V) spanning -0.31 to -1.15V versus Cp2Fe+/0. Kinetic studies were performed for the reactions of various [RuVI(por)O2], including [RuVI-(F28-tpp)O2] and [Ru VI(β-Br8-tmp)O2], with para-substituted styrenes p-X-C6H4CH=CH2 (X = H, F, Cl, Me, MeO), cis- and trans-β-methylstyrene, cyclohexene, norbornene, ethylbenzene, cumene, 9,10-dihydroanthracene, xanthene, and fluorene. The second-order rate constants (k2) obtained for the hydrocarbon oxidations by [RuVI-(F28-tpp)O2] are up to 28-fold larger than by [RuVI(F20-tpp)O2]. Dual-parameter Hammett correlation implies that the styrene oxidation by [RuVI(F28-tpp)O2] should involve rate-limiting generation of a benzylic radical intermediate, and the spin delocalization effect is more important than the polar effect. The k2 values for the oxidation of styrene and ethylbenzene by [RuVI-(por)O 2] increase with Ep.c(RuVI/V), and there is a linear correlation between log k2 and Ep.c(Ru VI/V). The small slope (≈2 V-1) of the log k 2 versus Ep.c(RuVI/V) plot suggests that the extent of charge transfer is small in the rate-determining step of the hydrocarbon oxidations. The rate constants correlate well with the C-H bond dissociation energies, in favor of a hydrogen-atom abstraction mechanism.
Epoxidation by sodium chlorite with aldehyde-promoted chlorine dioxide formation
Jangam, Ashok,Richardson, David E.
, p. 6481 - 6484 (2010)
An improved method is described for selective room temperature epoxidation of alkenes by sodium chlorite in a solvent mixture of ethanol, acetonitrile, and water buffered at pH 7. In addition, the use of aldehydes as promoters in chlorite oxidations is described for the first time. The amount of sodium chlorite, the solvent mixture, and the addition of formaldehyde as a practical promoter were optimized. Styrene was used as a test substrate in the optimization studies and the generality of the method was assessed by using a variety of nucleophilic and electrophilic substrates. Yields up to 89% were obtained with styrene and other nucleophilic alkenes are readily converted into epoxides.
Kinetics of (porphyrin)manganese(III)-catalyzed olefin epoxidation with a soluble iodosylbenzene derivative
Collman, James P.,Zeng, Li,Wang, Hong J. H.,Lei, Aiwen,Brauman, John I.
, p. 2707 - 2714 (2006)
We examined the kinetics of a well-behaved system for homogeneous porphyrin-catalyzed olefin epoxidation with a soluble iodosylbenzene derivative 1 as the terminal oxidant and Mn(TPFPP)Cl (2) as the catalyst. The epoxidation rates were measured by using the initial rate method, and the epoxidation products were determined by gas chromatography. The epoxidation rate was found to be first order with respect to the porphyrin catalyst and zero order on the terminal oxidant. In addition, we found the rate law to be sensitive to the nature and concentration of olefin substrates. Saturation kinetics were observed with all olefin substrates at high olefin concentrations, and the kinetic data are consistent with a Michaelis-Menten kinetic model. According to the observed saturation kinetic results, we propose that there is a complexation between the active oxidant and the substrate, and the rate-determining step is thought to be the breakdown of this putative substrate-oxidant complex that generates the epoxidation products and the resting state porphyrin catalyst. Competitive epoxidations further indicate a reversible complexation of the active oxidant and the olefin substrate. The activation parameters ΔH? and ΔS? for the oxygen-transfer process (k2) in the cis-cyclooctene epoxidation were determined to be 12.3±0.9 k cal mol-1 and -15.6±3.2 cal mol-1 K-1, respectively. In addition, the Hammett constant ρ+ was measured for the epoxidation of para-substituted styrenes, and the value of -0.27±0.04 is too low to be consistent with the involvement of a discrete carbocation in the transition state. We also prepared a (porphyrin)-manganese catalyst immobilized on silica support, and found the epoxidation of cis-cyclooctene catalyzed by this heterogeneous catalyst proceeds at virtually the same turnover frequency as by the homogeneous porphyrin catalyst. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
A Nanosized Gly-Decorated Praseodymium-Stabilized Selenotungstate Cluster: Synthesis, Structure, and Oxidation Catalysis
Yang, Ling,Li, Li,Guo, Jipeng,Liu, Qisen,Ma, Pengtao,Niu, Jingyang,Wang, Jingping
, p. 2441 - 2446 (2017)
A flexible one-pot strategy with pyramidal SeIV heteroatoms was employed for the assembly of the praseodymium-containing gly-decorated polyoxotungstate [{Pr3(H2O)10[Se2W22O76(gly)2]}2(Se2W7O30H2)]18? (1 a), which is constructed from one {Se2W7O30H2} unit and two identical {Pr3(H2O)10[Se2W22O76(gly)2]} units. Furthermore, the catalytic performance of Cs2Na4H12[{Pr3(H2O)10[Se2W22O76(gly)2]}2(Se2W7O30H2)]?25 H2O (1) for alkene epoxidation with hydrogen peroxide was investigated under mild reaction conditions, and the experimental results suggested that compound 1 exhibits good catalytic performance for the epoxidation of cyclooctene.
Substituent effects on the catalytic activity of a series of manganese meso-tetra(aryl)porphyrins: (2-, 3-, 4)-Pyridyl, 4-sulfonatophenyl and 3-sulfonato-4-methoxyphenyl groups compared to phenyl and 4-methoxyphenyl ones
Zakavi, Saeed,Mojarrad, Aida Ghanbelanie,Rayati, Saeed
, p. 153 - 158,6 (2012)
Catalytic activity and oxidative stability of a series of Mn-porphyrins (Mn-pors) with pyridyl (2-, 3- or 4-), 4-sulfonatophenyl, 3-sulfonato-4- methoxyphenyl, phenyl and 4-methoxyphenyl in oxidation of olefins with tetra-n-butylammonium periodate has been investigated in a comparative study. While the complexes with pyridyl substituents, MnT(py)P(OAc) are generally more stable than those with the other aryl groups toward oxidative degradation in reaction conditions, their catalytic activity is usually lower than these Mn-pors. MnT(4-py)P(OAc) was found to be unusually more stable than MnT(2- or 3-py)P(OAc). The order of catalytic performance of the used Mn-pors and their oxidative stability are less correlated with the electronic properties of the meso substituents. On the basis of indirect evidence obtained in competition oxidation of cis- and trans-stilbene, the involvement of a six coordinate (IO4)Mn(III)(Porphyrin)(ImH) and a high valent Mn-oxo species has been proposed. However, in the case of MnT(py)P(OAc), the latter seems to be more dominant than the former.
Catalytic properties of the homologous series of the β-brominated-pyrrole manganese(III) tetraphenylporphyrins
Rayati, Saeed,Nejabat, Fatemeh
, p. 52 - 57 (2016)
A homologous series of β-brominated Mn-porphyrins were prepared and their catalytic activities were investigated in the oxidation of cyclooctene with urea hydrogen peroxide (UHP). The highest conversion of cyclooctene with UHP in ethanol was obtained in t
Intramolecular arene hydroxylation versus intermolecular olefin epoxidation by (μ-η2:η2-peroxo)dicopper(II) complex supported by dinucleating ligand
Matsumoto, Takahiro,Furutachi, Hideki,Kobino, Masashi,Tomii, Masato,Nagatomo, Shigenori,Tosha, Takehiko,Osako, Takao,Fujinami, Shuhei,Itoh, Shinobu,Kitagawa, Teizo,Suzuki, Masatatsu
, p. 3874 - 3875 (2006)
A discrete (μ-η2:η2-peroxo)Cu(II)2 complex, [Cu2(O2)(H-L)]2+, is capable of performing not only intramolecular hydroxylation of a m-xylyl linker of a dinucleating ligand but also intermolec
Epoxidation of Styrene with Aqueous Hypochlorite Catalyzed by a Manganese(III) Porphyrin Bound to Colloidal Anion-Exchange Particles
Turk, Hayrettin,Ford, Warren T.
, p. 1253 - 1260 (1991)
Epoxidation of styrene in aqueous sodium hypochlorite solution was catalyzed by the tetrasodium salt of 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphinatomanganese(III) chloride (1).Manganese porphyrin 1 was more active bound to 60 nm diameter
