- Investigations of the Thermal Responsiveness of 1,4,2-Oxathiazoles
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The first systematic study of the thermal rearrangement/fragmentation of 5,5-disubstituted 1,4,2-oxathiazoles into isothiocyanates is reported. Structure-activity relationships reveal that the choice of substituent at the 5-position of the 1,4,2-oxathiazoles is the predominant factor to influence the ease of fragmentation.
- Hewitt, Russell J.,Ong, Michelle Jui Hsien,Lim, Yi Wee,Burkett, Brendan A.
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p. 6687 - 6700
(2015/10/29)
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- Thermolysis of 3,3,5,5-tetramethyl-1,2,4-trithiolane 1-oxide: First matrix isolation of the HOSS· radical
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Flash vacuum pyrolysis of 3,3,5,5-tetramethyl-1,2,4-trithiolane 1-oxide performed at 700 °C yields the 1-oxatrisulfan-3-yl radical (HOSS ·) along with disulfur monoxide (S2O) and diisopropyl sulfide, which were isolated in argon matrices at 10 K. Upon irradiation with UV light, the 1-oxatrisulfan-3-yl radical undergoes isomerization to the 1-oxatrisulfan-1-yl radical (HSSO·). Both radicals were identified by comparison of their computed and experimental IR and UV/Vis spectra. In addition, density functional theory (DFT) computations offer a plausible explanation of the most likely reaction mechanism, suggesting that the initial step is a 1,3-H shift with simultaneous ring opening. A 1-oxatrisulfane derivative formed thereby undergoes fragmentations via a radical and a competitive concerted pathway leading to the observed final products. The same mechanism also governs the thermal fragmentation of di-tert-butyl disulfide S-oxide. Its pyrolysis at 700 °C affords an analogous set of products, including the 1-oxatrisulfan-3-yl radical (HOSS·) as the key intermediate. 3,3,5,5-Tetramethyl-1,2,4-trithiolane 1-oxide was pyrolyzed in vacuo (FVP) yielding the 1-oxotrisulfan-1-yl radical, which was isolated in an Ar matrix at 10 K and subsequently characterized by spectroscopic methods (IR and UV/Vis). The same radical was obtained after vacuum pyrolysis of di-tert-butyl disulfide S-oxide.
- Reisenauer, Hans Peter,Mloston, Grzegorz,Romanski, Jaroslaw,Schreiner, Peter R.
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scheme or table
p. 3408 - 3415
(2012/09/11)
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- Photochemical formation and reactivities of substituted oxathiiranes in low-temperature argon matrices
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Thiocarbonyl S-oxides (sulfines) derived from aliphatic and cycloaliphatic thioketones were irradiated in argon matrices at 10 K, and the resulting oxathiiranes were identified by comparison of computed and experimental IR spectra. Upon photolysis at 10 K, depending on the substitution pattern, the oxathiiranes underwent either H-shift reactions or regioselective ring enlargements to form the corresponding thioesters. After warming of the matrix material to 38-40 K, the oxathiiranes underwent fast desulfurization to yield the corresponding ketones. Density functional theory (DFT) computations at the B3LYP/6-311+G(3df,3pd) level suggest that the desulfurizations of oxathiiranes occurred as bimolecular processes with activation enthalpies near 0 kcal mol-1.
- Reisenauer, Hans Peter,Mloston, Grzegorz,Romanski, Jaroslaw,Schreiner, Peter R.
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scheme or table
p. 6269 - 6275
(2011/12/02)
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- π-Face-selective hetero Diels-Alder reactions of 3,4-di-tert-butylthiophene 1-oxide. An excellent trapping reagent for thioaldehydes and thioketones
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Hetero Diels-Alder reactions of 3,4-di-tert-butylthiophene 1-oxide (1) with thioaldehydes and thioketones take place exclusively, except the reaction with thiobenzophenone, at the syn-π-face of 1 with respect to the S=O bond. The π-face selectivity was ex
- Takayama, Jun,Fukuda, Seiko,Sugihara, Yoshiaki,Ishii, Akihiko,Nakayama, Juzo
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p. 5159 - 5162
(2007/10/03)
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- Laser flash photolysis studies of oxygen and sulfur atom transfer reactions from oxiranes and thiiranes to singlet carbenes
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Laser flash photolysis (UV-LFP) studies of benzylchlorodiazirine (1a), phenylchlorodiazirine (1b), phenylmethoxydiazirine (1c), 2,2-dimethoxy-5,5- dimethyl-Δ3-1,3,4-oxadiazoline (6a), 3,4-diaza-2,2-dimethoxy 1- oxa[4.3]spirooct-3-ene (6b), 5',5'-dimethoxyspiro[adamantane]-2,2 -[Δ3- 1,3,4-oxadiazoline] (6c), and diazofluorene (DAF) in the presence of oxiranes and thiiranes are reported. These compounds, upon irradiation, afford benzylchlorocarbene (2a), phenylchlorocarbene (2b), methoxyphenylcarbene (2c), dimethylcarbene (8a), cyclobutylidene (8b), adamantylidene (8c), and fluorenylidene (FL), respectively. Absolute rate constants for the transfer of oxygen and sulfur atoms to these carbenes have been determined in both acetonitrile and cyclohexane solvents. These carbenes abstract oxygen and sulfur atoms with bimolecular rate constants ranging from 104 to 1010 M- 1 s-1 at 22 °C. Ylides from attack of carbenes onto heteroatom donors were not observed for any of the heteroatom transfer reactions. It was found that the magnitudes of the rate constants for heteroatom transfer are dependent on the philicity of the carbene intermediate, and trends in the kinetic data suggest that oxygen and sulfur atom transfers occur by concerted mechanisms through ylide-like transition states. The reactions of dimethoxycarbene (14) with cyclohexene oxide and propylene sulfide have been studied by the thermolysis of 6a, in benzene, at 110 °C. It was found that dimethoxycarbene also abstracts oxygen and sulfur atoms, albeit in low yields. It is concluded that, for singlet carbenes, carbene electrophiiicity is important in these heteroatom transfer processes.
- Pezacki, John Paul,Wood, Paul D.,Gadosy, Timothy A.,Lusztyk, Janusz,Warkentin, John
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p. 8681 - 8691
(2007/10/03)
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- Thiocyanohydrins, a new class of compounds, precursors of unstabilized thiocarbonyl derivatives
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Mono- and dialkylated thiocyanohydrins are prepared by alkylation of the parent compound 2 (NCCH2SH) under mild conditions. Some examples of the reactivity of this new class of compounds are also given.
- Gaumont,Wazneh,Denis
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p. 4927 - 4940
(2007/10/02)
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- SYNTHESIS OF ENETHIOLISABLE α-OXOTHIONES BY FLASH VACUUM THERMOLYSIS
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The retro Diels-Alder reaction of dihydrooxathiins and the retro-ene reaction of α-allylthio-carbonyl compounds were used to synthesise enethiolisable α-oxothiones.
- Bourdon, Francois,Ripoll, Jean-Louis,Vallee, Yannick
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p. 6183 - 6184
(2007/10/02)
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- The Gas-phase basicity and H/D Exchange Characteristics of the Parent Thiocarbonyl Enolate Anions
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The enethiolate anions corresponding to thioacetaldehyde and thioacetone, synthesized via elimination reactions, undergo H/D exchange reactions, demonstrating the intermediacy of the thiocarbonyl tautomers, and proton transfer reactions, leading to ΔG0acid = 341 +/- 3 kcal mol-1 and ΔG0acid = 344 +/- 3 kcal mol-1 (1 kcal = 4.184 kJ).
- Zhang, Lijian,Grabowski, Joseph J.
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p. 1819 - 1821
(2007/10/02)
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- Photoaddition of Olefins to Quinolin-, Isoquinolin- and Phthalazin-thione Systems
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Irradiation of quinolin-2-, isoquinolin-1-, and phthalazin-1-thiones with olefins afforded photoaddition products: substituted quinolines, isoquinolines and phthalazines at the thiocarbonyl carbon.A new addition-cyclization was found producing tricyclic thiopyrano-isoquinolines and -phthalazines.
- Sato, Eisuke,Ikeda, Yoshiya,Kanaoka, Yuichi
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p. 273 - 276
(2007/10/02)
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- GAS-PHASE THERMOLYSIS OF SULFUR COMPOUNDS. PART VI. ALLYL PROPARGYL AND ISOPROPYL PROPARGYL SULFIDES
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Allyl propargyl and isopropyl propargyl sulfides were pyrolyzed in a stirred-flow system at temperatures in the range 312-402 deg C and pressures between2 and 14 torr.The allyl propargyl sulfide yielded as products a mixture of propene and allene and the corresponding propynethial and propenethial.The thioaldehydes react at room temperature to form polymers and the Diels-Alder adduct 1,3-dithia-2-ethynyl-cyclohex-5-ene.The reaction products from isopropyl propargyl sulfide were allene and thioacetone.The reaction showed first order kinetics, with the rate coefficients following the Arrhenius equations Allyl Propargyl Sulfide:k(sec-1) = 1011.22+/-0.28exp(-139 +/- 3 kJ/mol RT), Isopropyl Propargyl Sulfide: k(sec-1) = 1011.51+/-0.14exp(-155 +/- 2 kJ/mol RT).The kinetic deuterium isotope effect of 4-thia-5-deutero-5-methyl-hex-1-yne pyrolysis was studied over the temperature range 370-402 deg C.
- Martin, Gonzalo,Lugo, Nery,Ropero, Marcos,Martinez, Henry
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- Gas Phase Reactions, 24. The Thermal Generation of Thiocarbonyl Compounds
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Thiocarbonyl derivatives R1R2C=S with R1, R2 = H, CH3, C6H5 can be generated thermally in the gas phase from a variety of precursors.Especially advantageous are the cleavage of propene from allyl sulfides or, for their preparation in pure form, the pyrolysis of dithietane or trithiolane derivatives.Photoelectron spectroscopy proves to be well-suited for gas analysis in the flow tube used, for the optimization of the decomposition conditions, and via assignment of the observed ionization patterns for the characterization of the thioaldehydes and thioketones prepared.
- Bock, Hans,Hirabayashi, Takakuni,Mohmand, Shamsher
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p. 492 - 503
(2007/10/02)
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- Etude des spectres de masse des thiocetones aliphatiques acycliques; mecanismes des fragmentations
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An examination of the mass spectra of aliphatic thioketones at 70 eV has shown some differences between these compounds and the corresponding ketones: the molecular ions of the thioketones were stronger than those of the ketones, indicating the greater ability of the sulfur atom to stabilise the radical cation; the loss of SH was found to be a characteristic fragmentation of aliphatic thioketones.
- Paquer, D.,Morin, L.,Vazeux, M.,Andrieu, C. G.
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- Pesticidal compositions containing phosphoric esters and divalent sulphur compounds
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Pesticidal composition comprising: a pesticidal, phosphoric ester the molecule of which has at least one alkyl group of 1 to 3 carbon atoms, 0.05 to 10% of an agent stabilizing the said ester against decomposition by protonisation, together with adjuvants characterized in that the stabilizing agent comprises at least one sulphur compound containing per molecule at least one divalent sulphur atom of which one valence is bonded to an atom chosen from sulphur, carbon, nitrogen, hydrogen, and metals capable of giving a salt, the other valence being bonded to an atom chosen from hydrogen, the carbon atom already noted, a second carbon atom, the nitrogen atom already noted, a second nitrogen atom, the metal atom already noted in the case of a metal of valence greater than one, a second atom of metal and oxygen when the first valence is not attached to an atom of hydrogen, the proportion of sulphur calculated with reference to the weight of the sulphur compound being between 5 and 99%. Process for stabilizing a phosphoric ester of which the molecule possesses at least one alkyl group containing 1 to 3 carbon atoms characterized in that there is added to the phosphoric ester or to a mixture which contains it, 0.05 to 10% calculated on the weight of the phosphoric acid ester of an agent capable of stabilizing the said phosphoric ester against protonisation and comprising at least one sulphur compound such as that defined thereupon.
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