- Air atmospheric photocatalytic oxidation by ultrathin C,N-TiO2nanosheets
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Herein, we demonstrate the highly efficient photocatalytic sulfide oxidation reaction under mild conditions,i.e.in air, at room temperature and in the absence of a sacrificial reagent, co-catalyst or redox mediator, by using ultrathin C,N-TiO2nanosheets as a photocatalyst.
- Cheng, Xiuyan,Zhang, Jianling,Liu, Lifei,Zheng, Lirong,Zhang, Fanyu,Duan, Ran,Sha, Yufei,Su, Zhuizhui,Xie, Fei
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supporting information
p. 1165 - 1170
(2021/02/26)
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- A novel binuclear iron(III)-salicylaldazine complex; synthesis, X-ray structure and catalytic activity in sulfide oxidation
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A novel binuclear iron(III)-salicylaldazine complex has been synthesized and characterized by various techniques such as IR and UV–Vis spectroscopy and X-ray crystallography. The catalytic oxidation of sulfides in the presence of the aforementioned complex was explored at room temperature using urea hydrogen peroxide (UHP) as an oxidant. Effects of different reaction conditions consisting catalyst and oxidant amount, solvent effect and reaction time on the catalytic activity and selectivity in the reaction of methylphenylsulfide oxidation has been surveyed. Perfect selectivity toward sulfoxide was achieved after 15 min in CH3CN by choice of a properly optimized reaction condition.
- Akbari, Ali,Amini, Mojtaba,Bagherzadeh, Mojtaba,Ellern, Arkady,Mesbahi, Elnaz,Woo, L. Keith
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- Selective catalytic oxidation of sulfides to sulfoxides or sulfones over amorphous Nb2O5/AC catalysts in aqueous phase at room temperature
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Selective oxidation of sulfides into sulfoxides or sulfones is an important transformation in organic synthesis. Activated carbon supported Nb-based catalysts were prepared by the impregnation method and then characterized by the XRD, TEM and XPS. The characterization results indicate Nb species is amorphous Nb2O5. The catalysts were applied for the catalytic oxidation of sulfides in aqueous phase with H2O2 as the oxidant. Sulfides could be converted into the corresponding sulfoxides or sulfones with high conversion and selectivity at room temperature. The recycling experiments showed the Nb2O5/AC catalysts exhibited good reusability. They could be recycled for 10 times without obvious loss of activity and selectivity.
- Zhang, Junjie,Jiang, Tingting,Mai, Yuliang,Wang, Xi,Chen, Jiazhi,Liao, Bing
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- Generation of VBr? VBi? VO?? defect clusters for 1O2 production for molecular oxygen activation in photocatalysis
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Defect engineering on a semiconductor surface can provide coordinatively unsaturated sites for molecular oxygen activation in photocatalysis. In this work, we demonstrated that the vacancy type was key to modulate the molecular oxygen activation process on BiOBr nanosheets. By regulating the reaction time, an oxygen vacancy (VO??), a double atom defect cluster (VBi? VO??) and triple atom clusters (VBi? VO?? VBi? and VBr? VBi? VO??) were accordingly generated on the surface, subsurface and bulk of BiOBr. More importantly, the newly-discovered VBr? VBi? VO?? defect cluster was highly related to the singlet oxygen (1O2) production ability of BiOBr. Meanwhile, the excellent photocatalytic selective oxidation reactions were successfully realized over BiOBr with the VBr? VBi? VO?? defect cluster. In addition, time-dependent defect cluster generation and the associated molecular oxygen activation were discussed.
- Ding, Jie,Dai, Zan,Tian, Fan,Zhou, Bo,Zhao, Bin,Zhao, Huiping,Chen, Zhiquan,Liu, Yunling,Chen, Rong
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supporting information
p. 23453 - 23459
(2017/11/30)
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- Chemoselective oxidation of sulfides to sulfoxides with urea hydrogen peroxide (UHP) catalyzed by non-, partially and fully β-brominated meso-tetraphenylporphyrinatomanganese(III) acetate
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Selective oxidation of sulfides to sulfoxides with urea hydrogen peroxide in the presence of the manganese complex of non-, partially and fully brominated meso-tetraphenylporphyrin, (MnTPPBrx(OAc) (x = 0, 2, 4, 6 and 8)) is reported. Although, the maximum conversion was achieved in the case of MnTPPBr4(OAc), little difference was found between the catalytic activity of MnTPP(OAc), MnTPPBr2(OAc) and MnTPPBr4(OAc). MnTPPBr8(OAc) showed an unusually very low catalytic efficiency compared to the other manganese porphyrins. The presence of small amounts of acetic acid was shown to have significant effect on the total conversion and the oxidative stability of the catalyst.
- Rayati, Saeed,Nejabat, Fatemeh,Zakavi, Saeed
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- Synthesis and characterization of 3-[N,N′-bis-3-(salicylidenamino) ethyltriamine] Mo(vi)O2@SBA-15: A highly stable and reusable catalyst for epoxidation and sulfoxidation reactions
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The efficient and reusable oxidation catalyst 3-[N,N′-bis-3- (salicylidenamino)ethyltriamine] Mo(vi)O2@SBA-15 has been synthesized by the anchoring of the 3-[N,N-bis-3-(salicylidenamino)ethyltriamine] ligand (L or Salpr) on the inner surfaces of organofunctionalized SBA-15 and subsequent complexation with Mo(vi)O2(acac)2. The physico-chemical properties of the functionalized catalysts were analyzed by elemental analysis, ICP-OES, XRD, N2-sorption measurements, TG & DTA, solid state 13C, 29Si NMR spectroscopy, FT-IR, Raman spectroscopy, XPS, DRS UV-Vis spectroscopy, SEM and TEM. XRD and N2 sorption analyses helped to find out the morphological and textural properties of the synthesized catalysts and confirm that an ordered mesoporous channel structure was retained even after the multistep synthetic procedures. The (100), (110) and (200) reflections in SBA-15 provide hints of a good structural stability, the existence of long range ordering and a high pore wall thickness. TG and DTA results reveal that the thermal stability of (L)Mo(vi)O2@SBA-15 was maintained up to 300°C. The organic moieties anchored over the surface of the SBA-15 support were determined by solid state 13C NMR and FT-IR spectroscopy. Further, solid state 29Si NMR spectroscopy provides the information about the degree of functionalization of the surface silanol groups with the organic moiety. The electronic environment and the oxidation state of the molybdenum site in (L)Mo(vi)O2@SBA-15 were monitored by Raman spectroscopy, XPS and DRS UV-Vis techniques. Moreover, the morphology and topographic information of the synthesized catalysts were confirmed by SEM and TEM imaging. The synthesized catalysts were evaluated in epoxidation and sulfoxidation reactions, and the results show that (L)Mo(vi)O2@SBA-15 exhibits high conversion and selectivity towards epoxidation and sulfoxidation reactions in combination with high stability. The anchored solid catalysts can be recycled effectively and reused several times without major loss in activity. In addition, Sheldon's hot filtration test was also carried out.
- Lazar, Anish,Thiel, Werner R.,Singh
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p. 14063 - 14073
(2014/04/17)
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- Selective oxidation of sulfides and olefins by a manganese (III) complex containing an N,O-type bidentate oxazine ligand
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A new manganese(III) complex [(N-O)2Mn(OAc)] was synthesized using 2-(2'-hydroxyphenyl)-5,6-dihydro-1,3-oxazine (N-O) as a bidentate O, N donor. The complex has been characterized by elemental analysis, IR, UV-vis spectroscopy, and X-ray structure analysis. Oxidation of sulfides and epoxidation of olefins, respectively, to their corresponding sulfoxides and epoxides were conducted by this catalyst using urea hydrogen peroxide as oxidant at room temperature under air. The catalyst is efficient in oxidation reactions giving high yields and selectivities.
- Amini, Mojtaba,Bagherzadeh, Mojtaba,Moradi-Shoeili, Zeinab,Boghaei, Davar M.,Ellern, Arkady,Woo, L. Keith
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p. 464 - 472
(2013/08/24)
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- Selective oxidation of nonrefractory and refractory sulfides by cyclopentadienyl molybdenum acetylide complexes as efficient catalysts
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The synthesis and catalytic properties of molybdenum acetylide complexes CpMo(CO)3(-C≡CR), R = Ph(1), C6H4-p- CF3 (2) and C6H4-p-CH3 (3) has been studied. The molybdenum acetylide complexes were synthesized from CpMo(CO) 3Cl and aryl acetylenes via Stephens- Castro coupling reaction. These complexes were characterized by single crystal X-ray diffraction analysis, FTIR and 1H NMR spectroscopy. These complexes on treatment with hydrogen peroxide, formed corresponding molybdenum oxo-peroxo species. These in situ formed oxo-peroxo species were found very active (up to 100 % conversion) and selective (up to 100 %) oxidation catalysts for various refractory and nonrefractory sulfides. Interestingly, even though the molybdenum acetylide complexes are homogeneous, they could be recycled very efficiently by extracting the catalytically active molybdenum oxoperoxo species in aqueous phase. Springer Science+Business Media, LLC 2012.
- Chandgude, MacChindra G.,Biradar, Ankush V.,Kotbagi, Trupti V.,Puranik, Vedavati G.,Dongare, Mohan K.,Umbarkar, Shubhangi B.
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p. 1352 - 1360
(2013/01/15)
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- CARBOCATALYSTS FOR CHEMICAL TRANSFORMATIONS
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The disclosure relates to catalytically active carbocatalysts, e.g., a graphene oxide or graphite oxide catalyst suitable for use in a variety of chemical transformations. In one embodiment, it relates to a method of catalyzing a chemical reaction of an organic molecule by reacting the organic molecule in the presence of a sufficient amount of graphene oxide or graphite oxide for a time and at a temperature sufficient to allow catalysis of a chemical reaction. According to other embodiments, the reaction may be an oxidation reaction, a hydration reaction, a dehydrogenation reaction, a condensation reaction, or a polymerization reaction. Some reactions may include auto-tandem reactions. The disclosure further provides reaction mixtures containing an organic molecule and graphene oxide or graphite oxide in an amount sufficient to catalyze a reaction of the organic molecule.
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-
Page/Page column 58-59
(2011/12/14)
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- Controlled oxidation of organic sulfides to sulfoxides under ambient conditions by a series of titanium isopropoxide complexes using environmentally benign H2O2 as an oxidant
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Controlled oxidation of organic sulfides to sulfoxides under ambient conditions has been achieved by a series of titanium isopropoxide complexes that use environmentally benign H2O2 as a primary oxidant. Specifically, the [N,N′-bis(2-oxo-3-R1-5-R2- phenylmethyl)-N,N′-bis(methylene-R3)-ethylenediamine]Ti(O iPr)2 [R1 = t-Bu, R2 = Me, R 3 = C7H5O2 (1b); R1 = R2 = t-Bu, R3 = C7H5O2 (2b); R1 = R2 = Cl, R3 = C7H 5O2 (3b) and R1 = R2 = Cl, R 3 = C6H5 (4b)] complexes efficiently catalyzed the sulfoxidation reactions of organic sulfides to sulfoxides at room temperature within 30 min of the reaction time using aqueous H2O 2 as an oxidant. A mechanistic pathway, modeled using density functional theory for a representative thioanisole substrate catalyzed by 4b, suggested that the reaction proceeds via a titanium peroxo intermediate 4c′, which displays an activation barrier of 22.5 kcal mol-1 (ΔG?) for the overall catalytic cycle in undergoing an attack by the S atom of the thioanisole substrate at its σ*-orbital of the peroxo moiety. The formation of the titanium peroxo intermediate was experimentally corroborated by a mild ionization atmospheric pressure chemical ionization (APCI) mass spectrometric technique. The Royal Society of Chemistry 2010.
- Panda, Manas K.,Shaikh, Mobin M.,Ghosh, Prasenjit
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experimental part
p. 2428 - 2440
(2010/06/18)
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- Observed and calculated 1Hand 13C chemical shifts induced by the in situ oxidation ofmodel sulfides to sulfoxides and sulfones
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A series of model sulfides was oxidized in the NMR sample tube to sulfoxides and sulfones by the stepwise addition of meta-chloroperbenzoic acid in deuterochloroform. Various methods of quantum chemical calculations have been tested to reproduce the observed 1H and 13C chemical shifts of the starting sulfides and their oxidation products. It has been shown that the determination of the energy-minimized conformation is a very important condition for obtaining realistic data in the subsequent calculation of the NMR chemical shifts. The correlation between calculated and observed chemical shifts is very good for carbon atoms (even for the 'cheap' DFT B3LYP/6-31G* method) and somewhat less satisfactory for hydrogen atoms. The calculated chemical shifts induced by oxidation (the δd values) agree even better with the experimental values and can also be used to determine the oxidation state of the sulfur atom (-S-, -SO-, -SO2 -). Copyright
- Dracinsky, Martin,Pohl, Radek,Slavetinska, Lenka,Budesinsky, Milos
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experimental part
p. 718 - 726
(2011/05/15)
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- A General and Expeditious One-Pot Synthesis of Sulfoxides in High Optical Purity from Norephedrine-Derived Sulfamidites
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A general and simple procedure for preparing any kind of enantiomerically enriched sulfoxide starting from norephedrine-derived N-benzyloxycarbonylsulfamidite 3a is reported. After one-pot reaction of 3a with RMgX, HBF4, and R'MgX, a variety of sulfoxides 6 are obtained in ee usually higher than 93% and isolated yields ranging between 50 and 78%. The obtained configuration is tunable by simply electing the order of the addition of the reagents.
- Ruano, Jose L. Garcia,Alemparte, Carlos,Aranda, M. Teresa,Zarzuelo, Maria M.
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- Mechanisms of hydrogen-, oxygen-, and electron-transfer reactions of cumylperoxyl radical
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Rates of hydrogen-transfer reactions from a series of para-substituted N,N-dimethylanilines to cumylperoxyl radical and oxygen-transfer reactions from cumylperoxyl radical to a series of sulfides and phosphines have been determined in propionitrile (EtCN) and pentane at low temperatures by use of ESR. The observed rate constants exhibit first-order and second-order dependence with respect to concentrations of N,N-dimethylanilines. This indicates that the hydrogen- and oxygen-transfer reactions proceed via 1:1 charge-transfer (CT) complexes formed between the substrates and cumylperoxyl radical. The primary kinetic isotope effects are determined by comparing the rates of N,N-dimethylanilines and the corresponding N,N-bis(trideuteriomethyl)anilines. The isotope effect profiles are quite different from those reported for the P-450 model oxidation of the same series of substrates. Rates of electron-transfer reactions from ferrocene derivatives to cumylperoxyl radical have also been determined by use of ESR. The catalytic effects of Sc(OTf)3 (OTf = triflate) on the electron-transfer reactions are compared with those of Sc(OTf)3 on the hydrogen- and oxygen-transfer reactions. Such comparison provides strong evidence that the hydrogen- and oxygen- transfer reactions of cumylperoxyl radical proceed via a one-step hydrogen atom and oxygen atom transfer rather than via an electron transfer from substrates to cumylperoxyl radical.
- Fukuzumi, Shunichi,Shimoosako, Kanji,Suenobu, Tomoyoshi,Watanabe, Yoshihito
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p. 9074 - 9082
(2007/10/03)
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- Efficient oxidation of sulfides catalyzed by transition metal salts with molecular oxygen in the presence of aldehydes
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Oxidation of sulfides to sulfoxides and sulfones was achieved in moderate to high yields with a good selectivity, by using Fe2O3, MnO2, Cu(OH)2 and Cu(OAc)2 as catalyst, with molecular oxygen in the presence of isovaleraldehyde under mild conditions.
- Song, Guoqiang,Wang, Fan,Zhang, Hao,Lu, Xiaoling,Wang, Chen
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p. 2783 - 2787
(2007/10/03)
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- Effect of alcohols on the photooxidative behavior of diethyl sulfide
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The reactions of singlet oxygen with diethyl sulfide (Et2S) in benzene alcohol mixtures have been examined. The salient discoveries include: (1) the rate constants of product formation, kr, in benzene/methanol mixtures are a function of the concentration of methanol, (2) the ability of alcohols to supress physical quenching are a function of their pKa's, and (3) trapping experiments with diphenyl sulfoxide are consistent with two distinct intermediates. A mechanism which involves formation of a persulfoxide followed by reaction with methanol to give a hydroperoxy-methoxy sulfurane is consistent with all of the results.
- Clennan, Edward L.,Greer, Alexander
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p. 4793 - 4797
(2007/10/03)
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- THIENOIMIDAZOLE DERIVATIVES, THEIR PRODUCTION AND USE
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Benzimidazole derivatives of the formula (I): STR1 wherein the ring A is a thiophene ring which may optionally contain substitution in addition to the R 3 group; R 1 is hydrogen or an optionally substituted hydrocarbon residue which may be bonded through a heteroatom; R 2 and R 3 are independently a group capable of forming an anion or a group convertible thereinto; X is a direct bond or a spacer having an atomic length of two or less between the phenylene group and the phenyl group; and n is an integer of 1 or 2; or a salt thereof, have potent angiotensin II antagonistic activity and antihypertensive activity, thus being useful as therapeutic agents for treating circulatory system diseases such as hypertensive diseases, heart diseases (e.g. hypercardia, heart failure, cardiac infarction, etc.), strokes, cerebral apoplexy, nephritis, etc.
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- Photosensitized oxidation of furans; Part 18: A simple method for a one-pot synthesis of functionalized methyl cis-4-oxoalk-2-enoates
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Functionalized methyl cis-4-oxoalk-2-enoates 2 are synthesized in a one-pot procedure by singlet oxygen oxygenation of the corresponding 2-methoxyfurans 1 in methanol and reduction of the resulting hydroperoxides 4 and 5 by the sulfides 6 which are selectively oxidized into the sulfoxides 7. The synthetic method has a wide range of applicability and affords compounds 2 stereoselectively and in good yields; concomitantly the sulfoxides 7 are obtained in excellent yields.
- Iesce,Cermola,Piazza,Scarpati,Graziano
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p. 439 - 443
(2007/10/02)
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- Sulfoxidation of Thioethers using Titanium Silicate Molecular Sieve Catalysts
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Titanium silicate molecular sieves having MEL (TS-2) or MFI (TS-1) topology efficiently catalyse the oxidation of various thioethers to the corresponding sulfoxides and sulfones using dilute hydrogen peroxide (26 wtpercent) as an oxidising agent.
- Reddy, Ravinder S.,Reddy, J. Sudhakar,Kumar, Rajiv,Kumar, Pradeep
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- Nature of 2?/1?* Three-Electron-Bonded Chlorine Adducts to Sulfoxides
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Reaction of sulfoxide radical cations, R2SO.+, with chloride ions in acidic aqueous solutions (pH * electron.The same species is formed upon oxidation of sulfoxides by Cl2*, although only with relatively low rate constants.The measured λmax are 390, 400, and 410 nm for the R2SO...Cl species with R = Me, Et, and n-Pr, respectively.Equilibrium constants for R2SO.+ + Cl- R2SO...Cl have been determined to be 560, 600, and 575 M-1, for the same respective series of species (error limit +/- 20percent).It is considered that our three-electron-bonded species is identical with an electronically not further specified chlorine-atom adduct to sulfoxide, R2SO(Cl)., observed earlier in sulfoxide-containing solutions of carbon tetrachloride and dichloromethane.The R2SO...Cl exhibit oxidizing properties and are shown to oxidize, for example organic sulfides and disulfides (rate constants on the order of 108 M-1 s-1) or SCN- (rate constants on the order of 109 M-1 s-1).The optical and kinetic results are discussed in light of the electronic properties of the radical species.
- Kishore, Kamal,Asmus, Klaus-Dieter
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p. 7233 - 7239
(2007/10/02)
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- Radical Cations from One-electron Oxidation of Aliphatic Sulphoxides in Aqueous Solution. A Radical Chemical Study
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Sulphoxide radical cations, (R2SO)+., have been observed upon one-electron oxidation of simple aliphatic sulphoxides by strongly oxidizing radicals with redox potentials >/=+2 V, e.g.SO4-., (CH3I)+., (CH3IICH3)+, or Ti2+ in pulse-irradiated aqueous solutions.They exhibit optical absorptions in the u.v. with λmax depending on the substituent (e.g. 300, 320, and 330 nm for R=Me, Et, and Pr, respectively).Extinction coefficients are of the order of 103 mol-1dm-3cm-1.The sulphoxide radical cations exist only at low pH and are probably best formulated in terms of an adduct with one water molecule, (R2SOOH2)+.The pK values for the equilibrium (R2SOOH2)+R2SO(OH). + H+ have been estimated to be 5.6, 6.1, and 6.5, for R=Me, Et, and Pr, respectively, from yield measurements.The neutral R2SO(OH). is identical with the hydroxyl radical adduct to sulphoxides formed at any pH in the reaction of R2SO + .OH, and decays irreversibly into R. + RSO2- + H+.The sulphoxide radical cationsare very good oxidants.Absolute rate constants have been measured for their reactions with a variety of electron donors, namely, organic sulphides, dithia compounds, disulphides, Br-, I-, and SCN-.The optical and kinetic results are discussed in the light of the electronic properties of the radical species.
- Kishore, Kamal,Asmus, Klaus-Dieter
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p. 2079 - 2084
(2007/10/02)
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- A NEW SOURCE FOR GENERATION OF BENZYNE AND PYRIDYNE: REACTIONS OF O-HALOPHENYL (OR 3-BROMO-4-PYRIDYL) PHENYL SULFOXIDES WITH GRIGNARD REAGENTS
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o-Chloro- and o-bromophenyl phenyl sulfoxides and (3-bromo-4-pyridyl) phenyl sulfoxide were treated with Grignard reagents to generate benzyne (or 3,4-pyridyne) in THF.The o-iodophenyl derivative, on the other hand, gave mainly o-(arylsulfinyl)phenyl Grignard reagent.
- Furukawa, Naomichi,Shibutani, Tadao,Fujihara, Hisashi
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p. 2727 - 2730
(2007/10/02)
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- PHOTOSENSITIZED OXYGENATION OF CYCLIC SULFIDES. SELECTIVE C-S BOND CLEAVAGE
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TPP-Senzitized photooxidation of five-membered ring sulfides in aprotic solvent afforded C-S bond cleavage products, unlike six- and seven-membered ring sulfides which gave only S-oxidation products.The products as well as substitution and concentration effects suggest that C-S bond cleavage depends upon acidity of α-proton of persulfoxide intermediate.
- Takata, Toshikazu,Ishibashi, Koichi,Ando, Wataru
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p. 4609 - 4612
(2007/10/02)
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- SOME KINETIC ASPECTS OF THE ALCOHOLYSIS OF N,N'-DIARYLSULPHURDIIMIDES
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Kinetic determinations (at 22 deg C) show that the ethanolysis of N,N'-diarylsulphurdiimides 1 - 9, catalysed by anhydrous copper(II) chloride, obeys a first-order rate law with respect to N,N'-diarylsulphurdiimide.The logarithm of the observed first-order rate constants (at the same concentration of the catalyst) can be correlated with the Hammett ? substituent constants.The ethanolysis rate of 1 - 9 is increased by the electron-withdrawing effect of the substituents linked to the aromatic rings of N,N'-diarylsulphurdiimide.The observed first-order rate constant of the CuCl2-catalysed ethanolysis of N,N'-bis(p-tolyl)sulphurdiimide, 3, is directly proportional to the catalyst concentration: kobs = k2.The second-order rate constants, k2, of the alcoholysis of 3 were measured in four alcohols different from ethanol.These constants seem to be a function of the polarity of the reaction medium and of the steric hindrance of the alcohol.Finally, it was ascertained that the catalysing power of CuCl2 in the ethanolysis of 3 is higher than that of NiCl2 and CoCl2.
- Carpanelli, Corrado,Gaiani, Giovanni
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p. 503 - 506
(2007/10/02)
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- DECARBOXYLATION OF α-KETO CARBOXYLIC ACIDS BY PERSULFOXIDE
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Photosensitized oxygenation of diethyl sulfide in the presence of α-keto carboxylic acids caused oxidative decarboxylation of the acids by persulfoxide and gave carboxylic acids, carbon dioxide, diethyl sulfoxide and diethyl sulfone.
- Ando, Wataru,Miyazaki, Hajime,Akasaka, Takeshi
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p. 2655 - 2656
(2007/10/02)
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- CHEMISTRY OF SINGLET OXYGEN - 38. TEMPERATURE EFFECT ON THE PHOTOOXIDATION OF SULFIDES.
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The reactivity of diethyl sulfide with singlet oxygen has been determined at room temperature (23-24 degree C) and at minus 78 degree C in various solvents. Although the consumption of sulfide is much faster at minus 78 degree C, the rate of removal of singlet oxygen by sulfide is relatively independent of solvent and temperature. A comparison of the rate of product formation with the rate of singlet oxygen removal shows that over 97% quenching is observed in aprotic and about 10% in protic solvents at room temperature. At minus 78 degree C, the quenching process is suppressed in both protic and aprotic solvents. Surprisingly, 2,5-diphenylfuran showed a similar but much smaller effect of solvent and temperature.
- Gu,Foote
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p. 6060 - 6063
(2007/10/02)
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- Mechanism of the Reaction of Dialkyl Sulphides with Bromamine T in Alkaline Medium
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Bromamine T (p-MeC6H4SO2NBr-K+) reacts readily with dialkyl sulphides (R2S) to yield sulphoxides (R2SO) and sulphimides (R2SNTs).The kinetics of the reaction were investigated in buffered alkaline water-methanol solutions.In rate-determining steps HOBr and p-MeC6H4SO2NHBr formed in equilibrium reactions convert dialkyl sulphides into bromosulphonium (R2SBr+) intermediates (ρ* -1.22 and 1.11, ρI -13.3 and -14.4, respectively.).Electrophilic additions of Br+ to sulphur atom are significantly hindered by the steric effect of S-alkyl groups (δ 0.713 and 0.765, ρs 0.766 and 0.792, respectively).Products are rapidly formed from bromosulphonium ions by nucleophilic displacement with OH- and p-MeC6H4SO2NH- nucleophiles.Product distribution depends on pH and the concentration of p-MeC6H4SO2NH2 but is not influenced markedly by S-alkyl groups in sulphides.Results are compared with those obtained earlier for chloramine T.
- Ruff, Ferenc,Kucsman Arpad
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p. 1075 - 1080
(2007/10/02)
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