3185-99-7Relevant articles and documents
Hydrolytic stability and hydrogen peroxide activation of zirconium-based oxoclusters
Faccioli, Francesco,Bauer, Matthias,Pedron, Danilo,Sorarù, Antonio,Carraro, Mauro,Gross, Silvia
, p. 210 - 225 (2015)
The hydrolytic stability of [Zr6(OH)4O4{O(O)CC(CH3)=CH2}12] (Zr6), and [Zr6O4(OH)4{O(O)CCH2CH=CH2}12]2·6[CH2=CHCH2C(O)OH] (Zr12) oxoclusters in different environments was thoroughly investigated by FTIR, Raman, and X-ray photoelectron spectroscopy (XPS). Specific information about the local structures around the Zr centers during the stability tests was achieved by in situ extended X-ray absorption fine structure (EXAFS) measurements, and the exact compositions were determined by inductively coupled plasma MS (ICP-MS) and elemental analysis. By this multidimensional spectroscopic approach, an overview on the structures formed after different treatments could be gained. The stability of the oxoclusters was then investigated in the presence of hydrogen peroxide, and the formation of peroxo-metal complexes was detected. Thus, a kinetic study was performed in acetonitrile to evaluate the performances of the oxoclusters as oxygen transfer catalysts. The oxidation of methyl p-tolyl sulfide to the corresponding sulfoxide and sulfone was chosen as a model reaction; in some cases, an interesting selectivity towards the formation of the sulfone was found over more than 4700 catalytic cycles.
Evidence for cyclodextrin dioxiranes
Deary, Michael E.,Davies, D. Martin
, p. 17 - 29 (1998)
α-Cyclodextrin, β-cyclodextrin, 2,6-di-O-methyl-β-cyclodextrin, methyl-β-cyclodextrin and sucrose have been oxidised by aqueous bromine solution at neutral pH. Both ketone and carboxylic acid containing materials are among the products of the oxidations. For α-cyclodextrin there is clear 13C NMR evidence for the presence of a ketone group and its hydrate form. This together with the continued ability of the product to complex p-nitrophenol indicates that the ketone is present at the secondary rim of an intact cyclodextrin ring. A pH dependence for the reaction of bromine with cyclodextrin shows that the maximum rate of bromine loss roughly coincides with the maximum concentration of hypobromous acid, HOBr, indicating that this is the reactive species in these oxidations. The results are consistent with a mechanism involving attack by one of the secondary hydroxyls of cyclodextrin on HOBr, with Br- leaving to yield an intermediate dehydroxy hydroperoxy cyclodextrin that subsequently decomposes to a keto-cyclodextrin via a Kornblum-De La Mare-type reaction. An alternative pathway prevails when the reaction is carried out under alkaline conditions, where carboxylic acids are the principle products. The keto derivatives produced by bromine oxidation at neutral pH are capable of catalysing the oxidation of p-nitrophenol and aryl-alkyl sulfoxides by peroxomono-sulfate in an analogous way to cyclohexanone, which is known to form a dioxirane upon reaction with peroxomonosulfate. It is likely that dioxirane formation is responsible for the observed catalysis in the present case also.
Chemistry of Oxaziridines. 10. Selective Catalytic Oxidation of Sulfides to Sulfoxides Using N-Sulfonyloxaziridines
Davis, Franklin A.,Lal, Sankar G.,Durst, H. Dupont
, p. 5004 - 5007 (1988)
The chemoselective catalytic oxidation of aliphatic and aromatic sulfides to sulfoxides (90-95percent) using a buffered potassium peroxymonosulfate (Oxone) generated N-sulfonyloxaziridine is described.This oxidizing system is rapid and relatively intensitive to the reaction parameters and the structure of the sulfide.
Keggin-type polyacid clusters on apatite: Characteristic catalytic activities in solvent-free oxidation
Ichihara, Junko,Yamaguchi, Shunro,Nomoto, Takuya,Nakayama, Hirokazu,Iteya, Katsuma,Naitoh, Nozomu,Sasaki, Yoh
, p. 8231 - 8234 (2002)
We found that Keggin-type phosphometalates are effective catalysts for solvent-free oxidation with urea-H2O2 by dispersing on fluorapatite solid phase. In the solid phase system the phosphomolybdate (NH4)3PMo12O40 was more effective than the phosphotungstate (NH4)3PW12O40, whereas the latter was much superior to the former in the liquid-phase reaction with aqueous H2O2. In situ formation of novel peroxo-type species from (NH4)3PMo12O40/FAp and urea-H2O2, which may lead to the high catalytic activity in the solid phase system, was observed by 31P solid-state NMR.
Synthesis and characterization of a Sb(v)-containing polyoxomolybdate serving as a catalyst for sulfoxidation
Lu, Jingkun,Wang, Yaping,Ma, Xinyi,Niu, Yanjun,Singh, Vikram,Ma, Pengtao,Zhang, Chao,Niu, Jingyang,Wang, Jingping
, p. 8070 - 8077 (2018)
A Sb-containing Anderson-based polyoxomolybdate cluster, [(CH3)4N]4H8[Na5Sb3(Sb2Mo12O57)]·17H2O [1; (CH3)4N+ = TMA+], has been successfully synthesized by using an aqueous solution method and structurally characterized. In particular, UV-Vis spectroscopy has been employed to elucidate the stability of the polyoxoanions. Under mild conditions, the catalyst demonstrates high activity and selectivity for the sulfoxidation of various sulfides in the presence of hydrogen peroxide. For example, thioanisole undergoes up to 100% conversion and 100% sulfone selectivity at 25 °C in aqueous solution.
Optically active polyoxometalate-based silica nanohelices: Induced chirality from inorganic nanohelices to achiral POM clusters
Attoui, Mariam,Pouget, Emilie,Oda, Reiko,Talaga, David,Bourdon, Gwéna Lle Le,Buffeteau, Thierry,Nlate, Sylvain
, p. 11344 - 11353 (2018)
In order to investigate the principle of chiral induction from nanometric silica helices to polyoxometalate (POM) clusters, a series of optically active silica POM-based nanohelices (NANOPOMs) have been prepared by electrostatic grafting and direct adsorption of a-Keggin polyoxometalate [a-PW12 O40]3 to well-defined left-and right-handed silica nanohelices. UV/Vis, Raman, DRIFT, TEM, HR-TEM, EDS and circular dichroism (CD) spectroscopy were used to characterize these NANOPOMs, and confirm the presence of POM clusters as well as their interactions with the helical support. The optical activity of the left-handed and right-handed NANOPOMs has been proven by CD spectroscopy. Their CD spectra are mirror images of one another, showing cotton effects at around 214 and 276 nm, this last contribution corresponding to the oxygen-to-tungsten charge-transfer bands of Keggin polyoxoanions. The CD signal of POM clusters is strongly enhanced for NANOPOMs built by adsorption of POM onto silica nanohelices, indicating a better induced optical activity to POM clusters. These nanohelices are stable, recoverable and active catalysts in the oxidation of sulfides. To the best of our knowledge, the present research represents the first examples of optically active POM-containing silica nanohelices in which achiral POM clusters have been grafted onto silica nanohelices, and display chiroptical effects.
A Crown-Shaped Ru-Substituted Arsenotungstate for Selective Oxidation of Sulfides with Hydrogen Peroxide
Han, Mengdan,Niu, Yanjun,Wan, Rong,Xu, Qiaofei,Lu, Jingkun,Ma, Pengtao,Zhang, Chao,Niu, Jingyang,Wang, Jingping
, p. 11059 - 11066 (2018)
An acetate-bridged Ru-substituted arsenotungstate [H2N(CH3)2]14[As4W40O140{Ru2(CH3COO)}2]?22 H2O (1) has been synthesized and structurally characterized. Four Ru atoms occupy the respective lacunary S2 sites of the crown-shaped polyanion [As4W40O140]28?, and each Ru atom is coordinated by one As atom and five μ2-O atoms, comprising four from the S2 site and one from the acetate ligand. To the best of our knowledge, this coordination of the Ru atom, with an Ru?As bond length of 2.377(3)–2.387(3) ?, is unprecedented in polyoxometalate (POM) chemistry. Notably, 1 exhibits high efficiency, excellent selectivity, and good recyclability for the oxidation of sulfides with hydrogen peroxide (H2O2). Catalytic oxidation of various sulfides in the presence of 1 gives superior conversion and selectivity for sulfones in acetonitrile, whereas sulfoxides are obtained in methanol.
High Chemoselectivity in the Construction of Aryl Methyl Sulfones via an Unexpected C-S Bond Formation between Sulfonylhydrazides and Dimethyl Phosphite
Liu, Teng,Yu, Shiwen,Shen, Xiang,Li, Yixian,Liu, Jianjun,Huang, Chao,Cheng, Feixiang
, p. 153 - 160 (2021/10/04)
A highly chemoselective route to aryl methyl sulfones via an unexpected C S bond formation between sulfonylhydrazides and dimethyl phosphite catalyzed by NaI under mild conditions has been established. This transformation provides an alternative and metal-free pathway to acquire various aryl methyl sulfones in good to excellent yields. Notably, dimethyl phosphite was employed as a stable and readily available alkyl source.
Niobium(V) oxido tris-carbamate as easily available and robust catalytic precursor for the selective sulfide to sulfone oxidation
Bresciani, Giulio,Ciancaleoni, Gianluca,Crucianelli, Marcello,Gemmiti, Mario,Marchetti, Fabio,Pampaloni, Guido
, (2021/11/01)
The oxidation of the sulfide function promoted by a variety of vanadium compounds has been largely explored, whereas the use of homogeneous catalytic systems based on the heavier group 5 metals remains less explored. We report the use of easily available niobium and tantalum carbamates, i.e. [M(O2CNMe2)5] (M = Nb, 1; M = Ta, 2), [Nb(O2CNMe2)4], 3, [NbO(O2CNEt2)3], 4, and [NbCl3(O2CNEt2)2], 5, as effective catalysts for the conversion of a series of alkyl aryl and aromatic sulfides into the corresponding sulfones. NMR investigations on the performant niobium catalyst 4 unexpectedly revealed the substantial stability of this compound in the protic catalytic environment, and a plausible catalytic cycle was obtained by DFT studies. The two active catalytic species, i.e. 4 and its minor mono-methoxide derivative, presumably interconvert to each other exploiting the versatile coordination of the carbamato ligand.
