- Thermal degradation processes in polysulphide polymers investigated by flash pyrolysis gas chromatography/mass spectrometry
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Thermal degradation of four polysulphides, poly(methylenesulphide), poly(methylenedisulphide), poly(methylenetetrasulphide), and poly(styrenesulphide)-co-poly(methylenesulphide) have been investigated by pyrolysis gas chromatography/mass spectrometry technique (Py-GC/MS). The pyrolysis products detected by Py-GC/MS indicate that the thermal decomposition of these polymers yields cyclic sulphides by an intramolecular exchange process. The linear products with thiol end groups also form along with the cyclic products through a β-CH hydrogen transfer reaction.
- Sundarrajan, Subramanian,Ganesh, Kannan,Kishore, Kaushal,Surianarayanan, Mahadevan
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p. 491 - 496
(2007/10/03)
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- Synthesis of Heterocyclic Diynes and their Reaction with CpCo(CO)2
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The preparation of the heterocyclic diynes 1,16-dithia-3,8-cyclodecadiyne (1b), thia-3,8-cyclodecadiyne (11), 1-thia-6-selena-3,8-cyclodecadiyne (12), oxa-3,8-cyclodecadiyne (13), 1,6-dioxa-3,8-cyclodecadiyne (14), 1-oxa-6-thia-3,8-cyclodecadiyne (15), 1,6-diselena-3,8-cyclodecadiyne (26), thia-3,9-cycloundecadiyne (22a), thia-3,13-cyclopentadecadiyne (22b) and its selena analogues 23a, 23b is described.The thia and monoselena compounds are obtained by a thia- or selenacyclization of the corresponding dibromides.Compound 26 has been obtained by a Misumi coupling reaction.The thiacycloalkadienes of medium-sized rings (10, 11) react with CpCo(CO)2 to yield (2,5)thiophenophane derivatives.Acyclic thiadialkynes or thiacyclodialkynes of larger ring size (22b) with CpCo(CO)2 by cycloaddition.
- Gleiter, Rolf,Rittinger, Stefan,Langer, Heinrich
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p. 357 - 363
(2007/10/02)
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- The Molecular Structure of 1,3,5-Trithiane from Electron Diffraction
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The molecular structure of 1,3,5-trithiane has been determined by gas-phase electron diffraction at 466 K nozzle temperature.The experimental data are consistent with the chair conformation of the molecule with C3v symmetry.The ring is considerably more puckered than that of cyclohexane.The following lengths (rg), bond angles and torsional angle were obtained: S-C 1.812+/-0.004, C-H 1.114+/-0.004 Angstroem, C-S-C 99.1+/-0.4, S-C-S 115.8+/-0.1, H-C-H 109.7+/-1.2, S-C-S-C 65.2+/-0.5 deg.
- Bencze, Zsolt,Kucsman, Arpad,Schultz, Gyoergy,Hargittai, Istvan
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p. 953 - 956
(2007/10/02)
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- THE REACTION OF AQUEOUS THIOSULFATE WITH FORMALDEHYDE
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The reaction of aqueous thiosulfate with formaldehyde was followed by C-13 NMR and Raman spectroscopy.At pH 7 no reaction was observed.In acidic solution, the carbon containing compound formed was trithiane.No hydroxymethanesulfonate nor hydroxymethanesulfinate was observed.This indicates that intermediates in the reaction do not include sulfur oxyacids in oxidation states +2, +3, or +4.Therefore, the reaction involves auto-thiolysis of thiosulfate without redox reactions.Raman spectra reveal, in addition to trithiane, an equilibrium mixture of tri- and tetrathionate in a mole ratio corresponding to the overall stoichiometry:6HS2O2-+ 3CH2(OH)2 = (CH2S)3 + 3S3O62- + 6H2O Excess thiosulfate yielded elemental cyclooctasulfur, in addition to the above.Secondary reaction products correspond to those formed during the decomposition of polythionates.
- Meyer, B.,Hermanns, K.,Reddoch, J.
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p. 283 - 290
(2007/10/02)
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- Synthesis and Reactions of 2-Aryloxy-s-trithianes
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2-Aryloxy-s-trithianes 4 had been prepared from 1-tosyl-imino-1-SIV-1,3,5-trithiane and phenolates. - By self-condensation of 4 1,5-bis-(trithianyl)-1,3,5-trithiapentane 5 and triphenylorthoformate 7 are formed, accompanied by further products, which had been isolated in pure state and identified unambiguously by H-n.m.r. and mass-spectra.In the presence of acids the 2-aryloxy-s-trithianes 4 react with nucleophilic aromatic compounds such as phenoles, N,N-dimethylaniline, pyrrole, indole, and thiophenes to give the C-trithianylated products.With mercaptanes 2-alkylthio-s-trithianes are formed.
- Walther, H.,Gross, H.
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p. 939 - 950
(2007/10/02)
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- Stereoselective Enzyme-catalysed Oxidation-Reduction Reactions of Thioacetals-Thioacetal Sulphoxides by Fungy
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Enzymes present in the fungus Mortierella isabellina catalyse the transfer of an oxygen atom to the cyclic thioacetal 1,3-dithian and from 1,3-dithian 1-oxide, 1,3,5-trithian 1-oxide, and cis-1,3-dithian 1,3-dioxide.The oxidation of 1,3-dithian and the acyclic thioacetal bis-(p-tolylthio)methane to form the corresponding monosulphoxides occurred in the presence of growing cultures of Aspergillus foetidus and a Helminthosporium species.The degree and the preferred direction of stereoselectivity occurring during the asymmetric oxidation and reduction steps was deduced from the enantiomeric excess (e.e.) and absolute stereochemistry of the isolated 1,3-dithian 1-oxide and p-tolylthio-(p-tolylsulphinyl)metane.
- Auret, Barbara J.,Boyd, Derek R.,Breen, Fiona,Greene, Ruth M. E.,Robinson, Peter M.
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p. 930 - 933
(2007/10/02)
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- DARSTELLUNG UND EIGENSCHAFTEN VON SCHWEFELHALTIGEN SIEBENRINGEN 2. 1,2,4,6-TETRATHIEPAN
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Dilution of the yellow solution of polymeric thioform aldehyde in concentrated sulfuric acid with water leads to a mixture of compounds, which contains besides s-trithiane and an oxygen containing polymeric thioether some five to ten percent of 1,2,4,6-tetrathiepane.The properties of this compound are described.This reaction is an example for the conversion of polymer into cyclic thioethers.
- Weissflog, Eckhard
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p. 157 - 160
(2007/10/02)
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