- Phase-Transfer-Catalyzed Oxidation and Reduction of Organosulfur Compounds with Dichlorocarbene. Mechanism and Synthetic Utility
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Diaryl and dialkyl sulfoxides undergo facile phase-transfer-catalyzed (PTC) deoxygenation with dichlorocarbene at 25 deg C to afford excellent yields of sulfides.Comparisons of deoxygenation rates of dialkyl and diaryl sulfoxides suggest that steric acceleration occurs with the bulky sulfoxides while resonance interactions from aromatic rings retard the reduction.Less bulky sulfides also undergo the reverse reaction: addition of dichlorocarbene to the sulfide with hydrolysis of the dialkyl dichloromethylide with hydroxide ion to afford the corresponding sulfoxide. "Oxidation" of trans-thiadecalin by reaction with PTC dichlorocarbene addition followed by basic hydrolysis is highly stereoselective, affording 94 percent axial and 6 percent equatorial sulfoxide.
- Dyer, John C.,Evans, Slayton A.
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- Thermal Deposition of TiS Films from Volatile Ti(SBut)4
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Amorphous films of TiS are deposited by the low-pressure vapour-phase thermolysis of Ti(SBut)4 at 130-200 deg C.
- Bochmann, Manfred,Hawkins, Ian,Wilson, Ladislav M.
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- A Method To Generate and Study (CH3)2S+. Radical Cations. Reduction of Me2SO by H. Atoms in Aqueous HClO4 Solutions
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Radical cations (CH3)2S+. were found to be formed as intermediates in the reaction of dimethyl sulfoxide with hydrogen atoms in aqueous solutions containing high concentrations of HClO4.This method allows one to study the properties of this cation, e.g., by pulse radiolysis, under conditions which are not disturbed by usually rapid complexation with excess sulfide.Absolute rate constants were measured for the reactions of (CH3)2S+. with (CH3)2S (k=3.0+/-0.3)E9 M-1s-1), CH3SSCH3 (k=(4.0+/-0.4)E9 M-1s-1) and (t-Bu)2S (k=2.1E9 M-1s-1).The latter reaction leads to the formation of S(t-Bu)2>+ three electron-bonded radical cations which exhibit an optical absorption at 545 nm and equilibrate with the molecular radical cation (t-Bu)2S+. (λmax 310 nm).In the presence of chloride ions (CH3)2SCl (or its protonated form) with λmax 380 nm is formed.The (CH3)2S+. itself absorbs at 285 nm and is, in fact, assumed to exist as O(H)ClO3>+, possibly in equilibrium with OH2>+, i.e., in stochiometrically defined three-electron-bonded complexes with HClO4 or H2O.In pure H2O/HClO4 matrix an optically absorbing transient with λmax 335 nm is observed which is attributed to (HClO4)2+..
- Chaudhri, Shamim A.,Goebl, Manfred,Freyholdt, Torsten,Asmus, Klaus-Dieter
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- SYNTHESIS AND STRUCTURES OF SOME DIGLYCOLALDEHYDE THIOACETALS
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Diglycolaldehyde (2,2'-oxybisacetaldehyde, 1a) reacts with thiols under conditions similar to those for monosaccharides.The nature of the reaction products depends on the degree of α-substitution of the thiol.The acyclic dithioacetal 2a was the only product isolated when methanethiol was used, but mixtures of acyclic dithioacetals, cis-2,6-bis(alkylthio)-1,4-dioxanes, and trans-2,6-bis(alkylthio)-1,4-dioxanes were obtained when ethanethiol, 1-propanethiol, and 2-propanethiol were used.From 1a and 2-methylpropane-2-thiol the acyclic dithioacetal 2e and the cis (7) and trans (8) stereoisomers of 3,5-bis(tert-butylthio)-1,4-oxathiane were isolated.On the other hand, when diglycolaldehyde bis(dialkyl acetals) (9a-d) or 2,6-di-isopropoxy-1,4-dioxane (10) were treated with primary or secondary thiols in acid media, the acyclic dithioacetals were isolated as the only products.The acyclic dithioacetal 2e and the oxathiane derivatives 7 and 8 were obtained when 9a-d or 10 were treated with 2-methylpropane-2-thiol under the above conditions.
- Aparicio, F. J. Lopez,Benitez, F. Zorrilla,Gonzales, F. Santoyo
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- Chemical Conversions using Sheet Silicates: Novel Intermolecular Eliminations of Hydrogen Sulphide from Thiols
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Aliphatic primary and secondary thiols react in the interlamellar layers of ion-exchanged montmorillonite catalysts to produce dialkyl sulphides via intermolecular elimination of hydrogen sulphide; similar processes result in the production of diphenyl sulphide from benzenethiol and poly(phenylenemethylene) from α-toluenethiol.
- Ballantine, James A.,Galvin, Robert P.,O'Neil, Robert M.,Purnell, Howard,Rayanakorn, Mongkon,Thomas, John M.
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- Oxidation of Thiols by Radical Cations of Organic Sulfides
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Sulfur-centered radical cations from organic sulfides have been foun to oxidize thiols and thiolates to yield thiyl radicals.Absolute rate constants have been measured for the reaction of (t-But)2S(1+) radical with EtSH (1.6E9 M-1s-1), C6H5SH (6.0E9 M-1s-1), and cystaine, CySH (1.9E9 M-1s-1).The reactions of Me2S(1+) radical with EtSH, t-ButSH, C6H5SH, and cysteine occur with k = 1.8E9, 2.5E9, 7.2E9. and 9.4E8 M1-s-1, respectively.The three-electron bonded (Me2SSMe2)(1+) radical cation oxidizes the cysteine anion (CyS(1-)) with k = 8.1E9 M-1s-1 and C6H5SH with k = 5E8 M-1s-1, while its reactions with EtSH, t-ButSH, and CySH are slower by several orders of magnitude.The results of kinetics and product analysis are discussed in view of the pronounced tendency of the thiyl radical to undergo electrophilic addition reactions. the optical absorption spectrum of C6H5S radical is also repoted and shown to exhibit maxima at 460 and 295 nm with extintion coefficients of 2 500 and 10 000 M-1 cm-1, respectively.
- Bonifacic, M.,Weiss, J.,Chaudhri, Shamim A.,Asmus, K.-D.
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- A di-tert-butyl-terminated chain multi-sulfide synthesis method
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The invention provides a synthesis method for di-tert-butyl terminated chain polythiaether. The method is characterized by comprising the steps of: putting elemental sulfur and a catalyst (amino based metal-organic framework microporous material) into a reaction kettle, replacing the air in the reaction kettle with nitrogen, then injecting hydrogen sulfide, conducting stirring heating to 120-160DEG C, slowly injecting isobutene into the reaction kettle, then carrying out reaction at a pressure of 4-7MPa for 2-6 h, then cooling the reaction product to 100DEG C, performing purging with nitrogen, condensing the low-boiling point by-product tert-butyl mercaptan and di-tert-butyl sulfide, then performing recovery for reuse as a raw material, conducting filtering when the product is cooled to room temperature to obtain a di-tert-butyl terminated chain polythiaether product, and using the catalyst obtained by filtering repeatedly. The synthesis method provided by the invention has the characteristics of high yield, reusable catalyst, and reaction atom economy near 100%, realizes zero pollution and zero emission, and belongs to an environment-friendly synthesis method.
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Paragraph 0017; 0041; 0041
(2017/03/24)
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- A very useful and mild method for the deoxygenation of sulfoxide to sulfide with silica bromide as heterogeneous promoter
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Silica bromide (SB) as heterogeneous reagent and promoter is prepared from reaction of silica gel with PBr3 as a non-hydroscopic, filterable, cheap, and stable yellowish powder that can be stored for months. The results show that the SB is suitable and efficient reagent for deoxygenation of sulfoxides to the corresponding sulfides under mild conditions at room temperature. The easy availability of this reagent makes this simple procedure attractive and a practical alternative to the existing methods.
- Mohanazadeh, Farajollah,Veisi, Hojat,Sedrpoushan, Alireza,Zolfigol, Mohammad Ali,Golmohammad, Fereshteh,Hemmati, Saba,Hashemi, Majid
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- Process for the Removal By Oxidation, of Mercaptans Contained in Hydrocarbons
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The mercaptans R—SH contained in a hydrocarbon stream are oxidized to the corresponding (di)sulfides by means of a redox system which comprises trivalent iron and a heteropolyacid which allows the complete reoxidation of the reduced iron also with air.
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(2009/05/29)
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- Preparation of thioethers using SN1-active halides and zinc mercaptides
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SN1-Active (tertiary alkyl, allylic and benzylic) halides react with zinc mercaptides, prepared in situ by contacting mercaptans with either zinc carbonate or zinc sulphide, under optimised conditions, to afford thioethers in moderate to very good yields (50-95 percent). The method is particularly useful for the preparation of thioethers with at least one bulky alkyl group.
- Srinivas, S.,Srinivas, P.,Gurudutt, K. N.
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p. 1174 - 1176
(2007/10/03)
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- Three-electron bonded σ/σ* radical cations from mixedly substituted dialkyl sulfides in aqueous solution studied by pulse radiolysis
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The formation of several radical cations ([Ri,Rj]S S[Ri,Rj])+, ([Ri] 2S S[Rj]2])+ and ([R i,Rj]S S[Rj]2)+ with mixed alkyl substitution in aqueous solution has been investigated by means of pulse radiolysis. The following substituents were involved: Rij = H, methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl and octyl. Two methods of generation have been applied: (i) .OH-induced oxidation of a sulfide and (ii) one-electron reduction of the corresponding sulfoxide in very acidic solution. The 2σ/1σ * three-electron bonded (> S S +-type species exhibit optical absorptions with maxima ranging from 420 nm for (Me2S SH2)+ to 600 nm for ([Me,But]S S[But]2)+. The actual transition energy can be related to the electron induction by the substituents as concluded from a linear free energy correlation between the respective λmax and weighted Taft's inductive σ* parameters. For unbranched substituents λmax (in eV) = 1.40 (σ*)w + 2.65. Evidence is also provided for the destabilization of the three-electron bond by steric demands of bulky substituents and by the effect of the substitution pattern on the 'σ-lone pair' interaction. The latter becomes apparent by comparing ([Me2]S S[But]2)+ (λmax 545 nm) with ([Me,But]S S[Me,But])+ (λmax 510 nm). Kinetically, a number of rate constants have been determined for the forward and back reactions of the equilibrium > S.+ + S S S +. They are typically of the order of 109 dm3 mol-1 s -1 and 104-105 s-1, respectively. Equilibrium constants derived from these kinetic data range from 2.0 x 10 5 dm3 mol-1 for (Me2S SMe2)+ (confirming an earlier measurement) to ≤5 x 103 dm3 mol-1 for ([Me,But]S S[But]2)+. Their decrease parallels the total electron-releasing power of the substituents and the steric constraints exerted by them. The decay of the three-electron bonded radical cations includes first-order release of protons, possibly in association with the dissociation of the three-electron bond and second-order processes, presumably disproportionation. By and large, the kinetic stabilities are reflected in the trend in λmax, with shorter lifetimes referring to more red-shifted absorptions.
- Chaudhri, Shamim A.,Mohan, Hari,Anklam, Elke,Asmus, Klaus-Dieter
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p. 383 - 390
(2007/10/03)
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- The Dimethylhydroxysulfuranyl Radical
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By use of pulse radiolysis the one-electron reduction potentials, E0(DMS(.+)/DMS) and E0(DMS(.+)/DMS) and E0((DMS)2(.+)/2DMS) (dimethyl sulfide, DMS) were determined to be 1.66 +/- 0.03 and 1.40 +/- 0.02 V vs NHE, respectively.DMS(.+) was found to be in equilibrium with DMSOH(.) with a pKa = 10.2.The conditional equilibrium constant for the reaction DMSOH(.) + DMS ->//-1.DMSOH(.) reacts with O2 with a rate constant of 2E8 M-1 s-1, independent of pH (11-14).From this and other observations, we estimate the pKa for deprotonation of DMSOH(.) to exceed 17.From spectral and kinetic data, the maximum lifetime of the radical (DMS)2OH(.) was predicted to be 10 ns.The stability of DMS-X(.) (X = OH, I, Br, Cl) in aqueous solution was shown to correlate with the one-electron reduction potential of X(.).Comparison of gaseous and aqueous behavior of DMS-OH(.) reveals that aqueous solvation strongly stabilizes the S-O bond against dissociation into DMS and OH(.).The Gibbs free energy of solvation of DMSOH(.) was calculated to be -12 +/- 3 kcal/mol, an unusually large value for a neutral species.
- Merenyi, Gabor,Lind, Johan,Engman, Lars
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p. 8875 - 8881
(2007/10/03)
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- Rhenium catalyzed sulfoxide reduction
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A mild, efficient method for the catalytic reduction of sulfoxides to sulfides with triphenylphosphine and the catalyst ReOCl3(PPh3)2 (I) is reported. Aryl sulfoxides are reduced faster than alkyl, and the reaction is successful for sterically hindered sulfoxides and those with common organic functional groups.
- Arterburn, Jeffrey B.,Perry, Marc C.
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p. 7941 - 7944
(2007/10/03)
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- Deoxygenation and Desulphuration Reactions of Lithium: Part V - Reaction of Sulphoxides with Lithium
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Dialkyl and aralkyl sulphoxides are reduced to the corresponding sulphides in good yields by lithium in dimethoxyethane; however, the reaction of benzyl sulphoxides with lithium is more complex.
- Rajanikanth, B.,Ravindranath, B.
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p. 296 - 297
(2007/10/02)
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- RADICAL CATIONS OF ORGANIC SULPHIDES AND DISULPHIDES FORMED BY RADIOLYSIS: AN ELECTRON SPIN RESONANCE STUDY
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Exposure of dilute solutions of various organic sulphides in fluorotrichloromethane at 77 K to 60Co γ-rays gave species identified by their e.s.r. spectra as the parent radical cations.The average β-proton coupling (R2CHS.R)+ of ca. 20 G is about half that for the corresponding ether cations, indicating greatly reduced ?-? delocalisation.However, the spread of g-values (ca. 2.032, 2.015, 2.00) is much greater than that for the ether cations.These cations readily react with other disulphide molecules to form (R2S.-SR2)+ dimer cations.The spectrum for tetrahydrothiophene (tetramethylene sulphide) exhibits a large coupling to two axial protons (ca. 42 G) and two equatorial protons (ca. 19 G), the coupling constants again being about half those for tetrahydrofuran cations.However, conformational inversion did not occur below the softening point of the solids (ca. 160 K) in marked contrast with the ether cations.The three-and four-membered ring cations (ethylene and trimethylene sulphide cations) gave very similar spectra with gx = gy, and four equivalent protons having an isotropic coupling of ca. 31 G.Thus their structures are similar to the normal R2S.+ cations, the equivalence of the g-values being interpreted in terms of effective C-S-C bond angles (θ) close to 90 deg.This, in turn, implies that θ > 90 deg for the unconstrained cations.It is noteworthy that the ethylene oxide (oxirane) cation exhibits a smaller coupling to its four protons (16 G).This implies a drastic change in structure for the oxirane cation which is clearly not the case for the sulphur analogue.Disulphides of structure R-S-CH2-S-R form cyclic ?* radicals with weak S-S bonding, in marked contrast with the oxygen analogues (acetal cations) which have ?-structures conferring very high spin-density onto the CH2 protons.Other molecules containing two RSR units form similar cyclic ?* radicals.Persulphides of structure RS-SR readily give the ?-cations (RS.SR)+, characterised by g-values in the region of 2.035, 2.018, 2.002.The smaller range of g values for (PhS.-SPh)+ cations is interpreted in terms of ca. 30percent spin-delocalisation into both the benzene rings.
- Rao, Ramakrishna D. N.,Symons, M. C. R.,Wren B. W.
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p. 1681 - 1688
(2007/10/02)
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- Nucleophilic Substitution of Alkyl Halides by Zinc Salts: Part 4-Synthesis of Thioethers and Thiolesters
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A variety of alkyl halides including tertiary alkyl halides react smoothly with the zinc salts of thiols and thiolcarboxylic acids yielding thioethers and thiolesters.
- Rajanikanth, B.,Ravindranath, B.
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p. 1043 - 1045
(2007/10/02)
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