- Crack healing and reclaiming of vulcanized rubber by triggering the rearrangement of inherent sulfur crosslinked networks
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CuCl2 has been shown to effectively catalyze reshuffling of the inherent sulfur crosslinked networks of vulcanized rubber. Once activated, CuCl2-based complex catalysis enables disulfide metathesis through circulated crossover reactions among disulfide and polysulfide bonds without forming radicals and ionic intermediates. By taking advantage of this mechanism, the model material of this study, vulcanized polybutadiene rubber, acquires thermal remendability as characterized by repeated restoration of mechanical properties. Moreover, it can be reprocessed like thermoplastics. The compositions and fabrication of the model material simulate those of industrial vulcanized rubber, so as to facilitate formulation optimization under the circumstances close to the actual situation for possible future practical applications. It is hoped that the results of the present preliminary exploration would provide the basis for extending the service life and developing new recycling techniques of vulcanized rubber, which is produced, used and scrapped in large quantities every day.
- Xiang,Qian,Lu,Rong,Zhang
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supporting information
p. 4315 - 4325
(2015/08/11)
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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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- 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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- 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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p. 571 - 579
(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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- 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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- ELEKTROCHEMISCHE OXIDATION VON DITHIOCARBONSAEUREESTERN ZU ISOTHIAZOLEN
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Electrolysis of alkyl arenedithioates 1 in acetonitrile with benzyl-triethyl-ammonium chloride as supporting electrolyte yields 5-aryl-4-cyano-3-methyl-isothiazoles 4.A reaction path is discussed according to which the dithioesters 1 are chlorinated at the anode and subsequently react with 3-iminobutyronitrile (6), generated at the cathode, to form the isothiazoles 4.
- Voss, Juergen,Mischke, Peter,Adiwidjaja, Gunadi
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p. 261 - 274
(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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