Cleavage Of Sulfur-sulfur Bond Research Articles

A computational mechanistic study of the cleavage of sulfur-sulfur bond by Frustrated Lewis Pairs

A computational mechanistic study of the cleavage of sulfur-sulfur bond by Frustrated Lewis Pairs

The Key Heterolysis Selectivity of Divalent Sulfur–Sulfur Bonds for a Unified Mechanistic Scheme in the Thiosulfatolysis and Sulfitolysis of the Pentathionate Ion

The thiosulfatolysis and sulfitolysis of pentathionate were studied in the pH ranges 4.50–8.0 and 4.0–5.0 at T = (25.0 ± 0.1) °C by HPLC monitoring of the time‐dependence and distribution of different sulfur species. The two systems are first order with respect to both reactants. In contrast to tetrathionate, pentathionate and higher polythionates contain inequivalent divalent sulfur atoms; therefore, the complexity of the mechanism increases. The selective heterolytic cleavages of sulfur–sulfur bonds are essential steps for the time evolution and equilibrium distribution of the divalent sulfur species. A proposed eight‐step mechanistic model, which incorporates the proton equilibrium of sulfite and the heterolytic cleavage of divalent sulfur–sulfur bonds of hexathionate, was applied to evaluate the thiosulfatolysis and sulfitolysis of the pentathionate ion, and the kinetics of both systems are modulated by this mechanistic network.

On the Mechanism of the Copper-Mediated C–S Bond Formation in the Intramolecular Disproportionation of Imine Disulfides

The mechanism of the copper-mediated disproportionation of aromatic imine disulfides to benzothiazoles in the gas phase is investigated by experimental and theoretical methods. Application of infrared multiphoton dissociation and hydrogen/deuterium exchange experiments combined with density functional theory (DFT) calculations of the relevant molecular structures and the associated infrared spectra allows the identification of the observed ionic intermediates. The theoretical investigation of the possible reaction pathways supported by collision-induced dissociation experiments provides a consistent mechanistic picture of the reaction catalyzed by a single copper(I) ion. Activation of the substrate proceeds via homolytic sulfur-sulfur bond cleavage, yielding metal complexes in the formal +3 oxidation state; carbon-sulfur coupling and hydrogen-atom transfer complete the transformation to the products. Exploratory studies demonstrate that in the gas phase, the disproportionation of the imine disulfide can also be mediated by other metal ions via different either homo- or heterolytic mechanisms without involving high-valent intermediates.

Reactions of o-Aminothiophenol and o-Aminophenyl Disulfide with Itaconic Anhydride and (-)-Dimenthyl Itaconate: Access to Enantiomerically Pure 1,5-Benzothiazepines and Benzothiazolyl-2-methylacrylic Acid

A facile chemo- and regioselective reactions of o-aminothiophenol (o-ATP) with itaconic anhydride is described. 1,5-Benzothiazepinyl-3-acetic acid is obtained in 81% yield via the exclusive Michael type addition of the thiol unit from o-ATP to the carbon-carbon double bond in itaconic anhydride followed by an intramolecular anhydride ring opening with an amine unit. The moderately stereoselective Michael type addition of the thiol unit from o-ATP to (-)-dimenthyl itaconate to obtain a mixture of diastereomers in a 7:3 ratio in 82% yield has been demonstrated. The reductive sulfur-sulfur bond cleavage in the dicarboxylic acid, 2-({2-[2-(3-carboxybut-3-enoylamino)phenyldisulfanyl]phenylcarbamoyl}methyl)acrylic acid, to the corresponding benzothiazolyl-2-methylacrylic acid in 84% yield, instead of the desired benzothio-azocine is also reported.

Specificity of respiratory pathways involved in the reduction of sulfur compounds by Salmonella enterica.

The tetrathionate (Ttr) and thiosulfate (Phs) reductases of Salmonella enterica LT2, together with the polysulfide reductase (Psr) of Wolinella succinogenes, are unusual examples of enzymes containing a molybdopterin active-site cofactor since all formally catalyse sulfur-sulfur bond cleavage. This is in contrast to the oxygen or hydrogen transfer reactions exhibited by other molybdopterin enzymes. Here the catalytic specificity of Ttr and Phs has been compared using both physiological and synthetic electron-donor systems. Ttr is shown to catalyse reduction of trithionate but not sulfur or thiosulfate. In contrast, Phs cannot reduce tetrathionate or trithionate but allows whole cells to utilize elemental sulfur as an electron acceptor. Mechanisms are proposed by which the bacterium is able to utilize an insoluble sulfur substrate by means of reactions at the cytoplasmic rather than the outer membrane.

Oxidation of inorganic sulfur compounds: Chemical and enzymatic reactions

Microbial oxidation of inorganic sulfur compounds is governed by both chemical and enzymatic reactions. It is therefore essential to understand reactions possible in chemistry when we consider enzymatic reactions. Various oxidation states of sulfur atoms in inorganic sulfur compounds and chemical oxidation reactions as well as nucleophilic cleavage of sulfur-sulfur bonds are discussed. The scheme of enzymatic oxidation of sulfur compounds with S2-→> S0→> SO32-→> SO42-as the main oxidation pathway is discussed with thiosulfate and polythionates leading into the main pathway for complete oxidation to sulfate. Enzymatic reactions are related to chemical reactions and the use of inhibitors for S0→> SO32-and SO32-→> SO42-is discussed for analyzing and establishing reaction stoichiometries. The proposed pathway is supported by a variety of evidence in many different microorganisms including some genetic evidence if the oxidation steps include all the systems irrespective of oxidizing agents (O2, Fe3+, cytochromes etc.).Key words: sulfur, oxidation, chemical, enzymatic, reactions.

Interchange between monolayers on gold formed from unsymmetrical disulfides and solutions of thiols: evidence for sulfur-sulfur bond cleavage by gold metal

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInterchange between monolayers on gold formed from unsymmetrical disulfides and solutions of thiols: evidence for sulfur-sulfur bond cleavage by gold metalHans A. Biebuyck and George M. WhitesidesCite this: Langmuir 1993, 9, 7, 1766–1770Publication Date (Print):July 1, 1993Publication History Published online1 May 2002Published inissue 1 July 1993https://doi.org/10.1021/la00031a025RIGHTS & PERMISSIONSArticle Views817Altmetric-Citations158LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Reductive Cleavage of Sulfur-Sulfur Bonds with Sodium Hydrogen Telluride

Abstract Sodium hydrogen telluride is shown to be an effective reagent for reduction of alkyl, aryl and functionally substituted disulfides to thiols in good yield under mild conditions. Organic thiosulfites (Bunte salts) also give thiols through the corresponding disulfide on reaction with sodium hydrogen telluride.

Molybdenum-molybdenum and phosphorus-phosphorus or sulfur-sulfur bond cleavage reactions of organic substrates with compounds containing a metal-metal triple bond

(η 5 -MeC 5 H 5 )Mo(CO) 2 [(CH 3 ) 2 PS] cristallise dans le systeme orthorhombique, groupe d'espace P2 1 2 1 2 1 et sa structure est affinee jusqu'a R=0,026. (η 5 -C 5 H 5 )Mo(CO) 2 [S 2 CN(CH(CH 3 ) 2 ) 2 ] cristallise dans le systeme triclinique, groupe d'espace P1 avec R=0,038

Improved purification and sulfhydryl analysis of thiosulfate reductase

Thiosulfate reductase purified 900-fold from an extract of baker's yeast by a new procedure consisted of three charge-isomeric species, all with catalytic activity. Amino acid analysis of thiosulfate reductase and titrations with 5,5′-dithiobis(2-nitrobenzoate) and iodo[ 14C]acetate indicated only one cysteine residue per enzyme molecule. Alkylation of this cysteine with either iodoacetate or iodoacetamide did not inactivate the enzyme, indicating that sulfur-sulfur bond cleavage in the thiosulfate substrate does not require an enzymic sulfhydryl group as attacking nucleophile.

Organic sulfur chemistry. 42. Sulfur-sulfur bond cleavage processes. Selective desulfurization of trisulfides

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrganic sulfur chemistry. 42. Sulfur-sulfur bond cleavage processes. Selective desulfurization of trisulfidesDavid N. Harpp and Roger A. SmithCite this: J. Am. Chem. Soc. 1982, 104, 22, 6045–6053Publication Date (Print):November 1, 1982Publication History Published online1 May 2002Published inissue 1 November 1982https://doi.org/10.1021/ja00386a034RIGHTS & PERMISSIONSArticle Views923Altmetric-Citations70LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Sequence distribution of styrene units in poly(styrene-co-tetramethylene disulfide) obtained from chain transfer copolymerization

Copolymers obtained from radical styrene polymerization in the presence of poly(tetramethylene disulfide) were subjected to sulfur-sulfur bond cleavage by butyllithium. The resulting oligo-and poly (styrene) molecular weight distribution is identical with the sequence distribution of styrene sequences in the copolymer which proved to be a multiblock. From this, the apparent chain transfer constant of poly(tetramethylene disulfide) was calculated.

OXIDATION OF ORGANIC SULFUR COMPOUNDS WITH DINITROGEN TETROXIDE

Abstract Symmetrical disulfides were known to be oxidized with excess N2O4 to the corresponding sulfonic anhydride in good yields. We have found that the oxidation of methyl phenyl disufide or an intermediate, phenyl methanethiolsulfinate undergoes via forming the unstable intermediate, i.e. the thionitrite, which are derived by the cleavage of sulfur-sulfur bond of the subsrates. The oxidation products were symmetrical disulfides, thiolsulfonates, and sulfonic acids which were undoubtedly derived from the scission of sulfur-sulfur bond.

Sulfur-sulfur bond cleavage promoted by palladium(0) and Platinum(0) triphenylphosphine complexes

Sulfur-sulfur bond cleavage promoted by palladium(0) and Platinum(0) triphenylphosphine complexes

Kinetics of sulfur-sulfur bond cleavage in methylated methyl disulfide by nuclear magnetic resonance

Kinetics of sulfur-sulfur bond cleavage in methylated methyl disulfide by nuclear magnetic resonance

Light-induced single electron-transfer reactions between chlorophyll α and quinones in solution II. Some effects of non-quinonoid donors and acceptors: Riboflavin, thioctic acid and NADH

1. 1. Light-induced single electron-transfer reactions have been observed in two-component systems involving chlorophyll and riboflavin or thioctic acid and in three-component systems involving NADH, chlorophyll, and benzoquinone or riboflavin. 2. 2. In the chlorophyll-riboflavin system, illumination of acidic solutions leads to the formation of the semiquinone of riboflavin and, via a side reaction, to the destruction of chlorophyll. 3. 3. In the chlorophyll-thioctic acid system, excitation of thioctic acid produces a species (perhaps the biradical resulting from sulfur-sulfur bond cleavage) capable of forming free radicals upon interaction with an electronically excited chlorophyll molecule. 4. 4. In the three-component systems, from 2- to 8-fold enhancements in steady-state radical concentrations can be achieved by adding NADH to solutions of chlorophyll and acceptors.