- Formation of dimethyloligosulfides in Lake Kinneret: Biogenic formation of inorganic oligosulfide intermediates under oxic conditions
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The mechanism of formation of dimethyloligosulfides in Lake Kinneret was investigated by field and laboratory studies. The process was simulated under laboratory conditions using obligate aerobic and facultative bacteria that were isolated from Lake Kinneret and fed with different types of organo-sulfur nutrients. The lysis products of Peridinium gatunense - a dinoflagellate that dominates the phytoplankton population in Lake Kinneret during the winter - spring season - are the primary source of dimethyloligosulfides. Bacterial assimilation of the aged alga or algae lysis products yields inorganic oligosulfides, which are then methylated to form the dimethyloligosulfides. All the steps of this process are carried out under oxic conditions.
- Ginzburg, Boris,Dor, Inka,Chalifa, Irit,Hadas, Ora,Lev, Ovadia
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- Allium discoloration: The color-forming potential of individual thiosulfinates and amino acids: Structural requirements for the color-developing precursors
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Structural requirements for compounds involved in Allium discoloration have been investigated in detail. The abilities of all 20 protein amino acids and six naturally occurring 1-propenyl-containing thiosulfinates to form the pigments have been studied. Furthermore, several analogues of these thiosulfinates were prepared by synthesis, and their color-forming abilities were evaluated, together with those of various amino compounds. It has been found that an unsubstituted primary amino group and a free carboxyl group are essential structural features required for amino compounds to be able to generate the pigments. Out of the thiosulfinate analogues tested, only those containing at least a three-carbon chain with the β-carbon bearing a hydrogen atom yielded the pigments after reacting with glycine. Thiosulfonates, sulfoxides, sulfides, and disulfides did not form any colored products when mixed with glycine. The pH optimum for pigment formation has been found to be between 5.0 and 6.0 for all thiosulfinates tested.
- Kubec, Roman,Velisek, Jan
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- Effect of Zinc Oxide on the Thermal Decomposition of Dimethyl Sulfoxide
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Dimethyl sulfoxide (DMSO) is widely used in the chemical industry. However, it has a non-neglectful thermal runaway risk due to the nature of self-accelerating decomposition near the boiling point. Under the background that zinc oxide (ZnO) may extend the isothermal induction period of thermal decomposition of DMSO, this article conducts an in-depth study for the phenomenon with the techniques such as differential scanning calorimetry (DSC), accelerating rate calorimetry (ARC), gas chromatography-mass spectrometry (GC-MS), X-ray photoelectron spectroscopy (XPS), and X-ray diffractometry (XRD). After being mixed with ZnO, the maximum decomposition rate of DMSO was significantly reduced and the adiabatic induction period of DMSO decomposition was extended by 3.27 times, indicating that the thermal decomposition intensity of DMSO was obviously reduced. It was experimentally demonstrated that ZnO did not change the decomposition pathways of DMSO, but it could promote the decomposition of methanethiol, which was a decomposition intermediate of DMSO and could potentially serve as a promoter on the decomposition of DMSO.
- Chen, Liping,Chen, Wanghua,Guo, Zichao,Li, Huabo,Weng, Shichun,Wu, Wenqian
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- K2S as Sulfur Source and DMSO as Carbon Source for the Synthesis of 2-Unsubstituted Benzothiazoles
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We describe a three-component reaction of o-iodoanilines with K2S and DMSO that provides 2-unsubstituted benzothiazoles in moderate to good isolated yields with good functional group tolerance. Electron-rich aromatic amines and o-phenylenediamines instead of o-iodoanilines provided 2-unsubstituted benzothiazoles and 2-unsubstituted benzimidazoles with and without K2S under similar conditions. Notably, DMSO plays three vital roles: carbon source, solvent, and oxidant.
- Deng, Guobo,Kuang, Daizhi,Liang, Yun,Yang, Yuan,Yu, Jiangxi,Zhang, Fuxing,Zhu, Xiaoming
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supporting information
p. 3789 - 3793
(2020/06/04)
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- Catalytic reactions of dimethyl disulfide with thiophene and benzene
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The gas-phase reaction of dimethyl disulfide with thiophene proceeds under the action of acid catalysts under atmospheric pressure at 160-350°C and a residence time of τ = 0.6-21 s to form thioalkylation and alkylation products. Dimethyl disulfide reacts with benzene to form only alkylation products. Catalysts containing both strong protic and Lewis acid sites, as well as basic sites of moderate strength, are the most active ones.
- Mashkina,Khairulina
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- Chromatographic component of identification of the transformation products of 1,1-dimethylhydrazine in the presence of sulfur
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The gas-chromatographic retention indices of the products of 1,1-dimethylhydrazine transformations in the presence of sulfur allows one to confirm and, in ceratin cases, make more exact the results of their gas chromatography-mass spectrometry identificat
- Zenkevich,Ul'Yanov,Golub,Buryak
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p. 1106 - 1114
(2014/08/05)
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- Synthesis, stability, and reactivity of [(TPA)Zn(SH)]+ in aqueous and organic solutions
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Reaction of the complex [(TPA)Zn(H2O)]2+ [TPA = tris(2-pyridylmethyl)amine] with hydrogen sulfide in aqueous buffered solution gives the corresponding monomeric hydrogensulfido complex [(TPA)Zn(SH)] +, which was fully characterized, including by XRD. This complex is stable at neutral pH, but decomposes under basic conditions to yield the free ligand and zinc sulfide, and under acidic conditions to give hydrogen sulfide and the starting aqua complex. In organic solvents, the coordinated sulfur atom reacts with electrophiles such as methylmethanethiosulfonate to yield methyltrisulfide. Reaction with the hydroxo complex [(TpPh,Me)Zn(OH)] [TpPh,Me = hydridotris{(5-methyl-3-phenyl)pyrazolyl}borate] promotes the formation of the unsymmetrical dinuclear μ-sulfido species [(TPA)Zn-S-Zn(TpPh,Me)]+, which, upon treatment with one molar equivalent of trifluoroacetic acid, dissociates into [(Tp Ph,Me)Zn(SH)] and [(TPA)Zn(CF3CO2)] +, resulting in the transfer of the hydrogensulfido ligand from one zinc center to another.
- Galardon, Erwan,Tomas, Alain,Roussel, Pascal,Artaud, Isabelle
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scheme or table
p. 3797 - 3801
(2011/11/29)
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- Process for the preparation of organic disulfides
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The invention relates to a process for the preparation of organic disulfides by oxidation of mercaptans with sulfur dissolved in an organic disulfide using an amine as catalyst, where the mercaptans are used as “crude mercaptan stream” from a reaction of alcohols with hydrogen sulfide over a catalyst suitable for mercaptan synthesis. Furthermore, the invention relates to the use of the organic disulfides for the preparation of alkanesulfonic acids.
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Page column 5
(2008/06/13)
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- Sulfur-atom insertion into the S-S bond - Formation of symmetric trisulfides
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The reaction of triphenylmethanesulfenyl chloride (3a) with acyclic disulfides 4 or 5 give the respective trisulfides 1 or 2 in moderate to good yield and selectivity. A mechanism is advanced to explain the chemistry.
- Hou, Yihua,Abu-Yousef, Imad A.,Doung, Yen,Harpp, David N.
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p. 8607 - 8610
(2007/10/03)
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- Three sulfur atom insertion into the S-S bond - Pentasulfide preparation
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Chloro(triphenylmethyl)trisulfide (1) reacts under mild conditions with symmetric primary dialkyl disulfides and aromatic disulfides giving pentasulfides as the main products in good yield and selectivity. A mechanism involving a triphenylmethyl alkyl/phenyl tetrasulfide intermediate is discussed. (C) 2000 Elsevier Science Ltd.
- Hou,Abu-Yousef,Harpp
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p. 7809 - 7812
(2007/10/03)
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- Insertion of a two sulfur unit into the S-S bond - Tailor-made polysulfides
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Triphenylthiosulfenyl chloride (1) reacts with disulfides RSSR, yielding tetrasulfides as the main products. The results of the insertion for different R groups are reported. A two-step mechanism involving the formation of unsymmetrical trisulfide intermediates containing the trityl group is proposed. (C) 2000 Elsevier Science Ltd.
- Rys,Harpp
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p. 7169 - 7172
(2007/10/03)
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- Nucleophilic substitution of alkyl halides by electrogenerated polysulfide ions in N,N-dimethylacetamide
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The reactions between a series of alkyl halides RX: X = I, R = CH3 (1), C3H7 (2); X = Br, R = C4H9 (3), 2-C4H9 (4), 3-C5H11 (5), PhCH2 (6); X = Cl, R = PhCH2 (7), C6H13 (8), and electrogenerated S1/3- ions (S62- ?S3.-) have been investigated by spectroelectrochemistry in N,N-dimethylacetamide at 20°C. RX substrates react in two steps: (i) nucleophilic substitution of S1/3- ions (SN2 process) yielding RSx- ions (x = 5.2, R = alkyl; x = 4.8, R = PhCH2); (ii) subsequent substitutions of RSx- ions lead to RSzR polysulfanes (z ≈ 3.5), probably through partial disproportionation of the anionic species. On a preparative scale, mixtures of CH3SzCH3 (z = 2-6, z = 3.9) or PhCH2Sz CH2Ph (z = 2-5, z = 3.7) were obtained from chemical reactions between 1, 6 and S62- ions, or electrochemical syntheses. Kinetic studies at 20°C of the reactions between S3.- ions and substrates 4, 5, 7 and 8 imply that the dianions S62- are the nucleophilic agents in the first step rather than S3.- radical anions.
- Ahrika, Abdelkader,Robert, Julie,Anouti, Meriem,Paris, Jacky
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p. 513 - 520
(2007/10/03)
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- Hydrogen Sulfide Reactivity with Thiols in the Presence of Copper(II) in Hydroalcoholic Solutions or Cognac Brandies: Formation of Symmetrical and Unsymmetrical Dialkyl Trisulfides
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In the presence of copper(II), hydrogen sulfide reacts with thiols (methanethiol and ethanethiol) to yield symmetrical or unsymmetrical trisulfides (dimethyl trisulfide, diethyl trisulfide, and ethyl methyl trisulfide). In alcoholic beverages, these compounds are known for their nauseous character, reminiscent of onion smell, and for their low detection levels (dimethyl trisulfide: 0.1 μg/L). A mechanism for trisulfide formation is proposed that involves a two-step redox reaction.
- Nedjma, Mustapha,Hoffmann, Norbert
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p. 3935 - 3938
(2007/10/03)
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- Highly Efficient Solvents and Reagents for Elemental Sulfur
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Elemental sulfur is easily activated in the hydrazine hydrate-alkali system with formation of polysulfide anions. The procedure is developed for yielding highly concentrated solutions of alkali metal polysulfides. The latter compounds are readily alkylated with alkyl halides to form dialkyl polysulfides. The alkylation using higher alkyl halides (C7-C9) yields dialkyl sulfides that are difficult to prepare by other methods.
- Deryagina,Kozlov,Vershal',Babkin
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p. 1240 - 1243
(2007/10/03)
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- Solution reactivity of thiyl radicals with molecular oxygen: Unsensitized photooxidation of dimethyldisulfide
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Irradiation of dimethyldisulfide in a protic solvent in the presence of molecular oxygen leads to the formation of sulfonic and sulfuric acids as major products. The addition of molecular oxygen on the thiyl radical formed by S-S bond cleavage is postulated.
- Banchereau, Evelyne,Lacombe, Sylvie,Ollivier, Jean
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p. 8197 - 8200
(2007/10/02)
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- Reactions of dimethyl polysulfides with organomagnesium reagents
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Reactions of a mixture of dimethyl polysulfides (DMPS, CH3SxCH3, x = 3 - 8) with methyl- and phenylmagnesium halides are described.The type of product obtained was dependent on the molar ratio of DMPS to Grignard reagent.When a 6:1 methyl-Grignard to DMPS ratio was used, methanethiol and dimethyl sulfide were the major products obtained after acidification of the reaction mixture.Lesser quantities of methyl-Grignard favored the formation of dimethyl sulfide, dimethyl disulfide, and H2S.Experiments with a 6:1 phenylmagnesium bromide to DMPS ratio produced benzenethiol and phenylmethyl sulfide as major products after acidification.No methanethiol was observed in these experiments.Mixtures of phenylmethyl mono-, di- and trisulfides and H2S were obtained with a 3:1 Grignard/DMPS molar ratio.From a mechanistic viewpoint, product distributions obtained from reaction of Grignard reagents with DMPS can be explained by the formation of magnesium thiolates that are most readily stabilized by adjacent structures.Experiments using phenyl Grignard reagent in limited supply suggested that the internal sulfur atoms of the polysulfide chains were more reactive.
- Clark, Peter D.,Mann, Russell S.,Lesage, Kevin L.
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- SYNTHESIS OF DISULPHIDES AND TRISULPHIDES via ORGANOSILICON COMPOUNDS
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Silyl sulphides 2a-b smoothly react with thiolsulphinates 1a-c and thiolsulphonates 6a-c to give unsymmetrical disulphides under mild conditions and in very good yields.The "neutral" conditions used allow one to avoid any side reactions and subsequent randomization of the products.When bis(trimethylsilyl)sulphide, 8, is used, symmetrical trisulphides may be obtained under the same experimental conditions.
- Capozzi, Giuseppe,Capperucci, Antonella,Degl'Innocenti, Alessandro,Duce, Rosa Del,Menichetti, Stefano
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p. 421 - 426
(2007/10/02)
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- SILICON IN ORGANOSULFUR CHEMISTRY. Part 1. SYNTHESIS OF TRISULPHIDES
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The reaction of bis(trimethylsilyl)sulphide with thiosulphinates in an inert solvent under neutral and mild conditions gives symmetrical alkyl- or aryl-trisulphides.
- Capozzi, Giuseppe,Capperucci, Antonella,Degl'Innocenti, Alessandro,Duce, Rosa Del,Menichetti, Stefano
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p. 2991 - 2994
(2007/10/02)
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- SCAVENGING OF RADICALS FROM THE GAS PHASE BY FREEZING WITH DIMETHYL DISULFIDE: 1. TEST OF THE METHOD FOR LIGHT RADICALS.
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H and O atoms and methyl radicals produced in microwave discharges of H//2/He, O//2/He and CH//4/He mixtures, respectively, were scavenged by supersonic nozzle probing with subsequent freezing and reaction with dimethyl disulfide on a liquid nitrogen cooled wall. The main reaction products for the three kinds of radicals were CH//3SH, CH//3S(O)SCH//3 and CH//3SCH//3, respectively. The scavenging efficiencies for the different radicals were determined and measured as a function of the gas phase radical concentration, the flow of scavenger molecules, the pressure in the vacuum chamber, and the conditions of the discharge and the flow through the sampling nozzle. It is concluded that this method is suitable for light radicals with reservations in the case of H atoms and can probably be used with still better success for heavier radicals.
- Schottler,Homann
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p. 688 - 694
(2007/10/02)
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- Synthesis and Characterisation of Bispolysulphanes
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Bispolysulphanes with a linear chain of 1-6 sulphurs have been prepared and characterised; in particular X-ray crystallographic analyses proved the structures of the tri- and tetra-sulphanes.The tri-to hexa-sulphanes were formed by reactions of O,S-dimethyl dithiocarbonate with the appropriate dichlorosulphane containing two less sulphurs.The disulphane was prepared by chlorination of O-t-butyl S-methyl dithiocarbonate or by controlled desulphurisation of the trisulphane using triphenylphosphine; further desulphurisation provided the monosulphide. (Methyl thio)carbonylsulphenyl chloride is proposed as an intermediate in the above chlorination; it was synthesised by an indirect route and shown to rearrange to its isomer, (methylthio)carbonyl chloride.
- Mott, Andrew W.,Barany, George
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p. 2615 - 2621
(2007/10/02)
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- Reaction of methanethiol with species produced in a microwave discharge through water vapor
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The products of reaction of methanethiol with species produced by passage of water vapor through a microwave discharge were studied.Mass spectrometric analysis demonstrated the presence of SO2, CH3SSCH3, CH3SSSCH3, CH3SSSSCH3, CH3SSCH2SCH3, CH3SCH2SCH3, and S8.These products are consistent with a mechanism involving abstraction of hydrogen from CH3SH by OH and other radicals as the important primary process.
- Chang, C. H.,Goodfriend, P. L.,Bentley, M. D.,Anderegg, R. J.
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p. 1617 - 1619
(2007/10/02)
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