16812-19-4Relevant academic research and scientific papers
Rate Constants and Arrhenius Functions for Hydrogen Atom Transfer from tert-Butyl Thiol to Primary Alkyl Radicals
Newcomb, Martin,Glenn, Anne G.,Manek, M. Beata
, p. 4603 - 4606 (1989)
The radical clock method was used to determine rate constants for hydrogen atom transfer from t-BuSH to primary alkyl radicals over the temperature range -45 to 50 deg C.Three clocks, cyclization of the 5-hexenyl radical (3a), ring opening of the cyclopropylcarbinyl radical (3b), and rearrangement of the 2,2-dimethyl-3-butenyl radical (3c), were used in THF, and 3a was used in toluene.Arrhenius functions for the two studies with 3a and the one with 3b were quite similar, and the Arrhenius function for 3c, when adjusted for direct comparison to reactions with simple primary radicals, was also similar.Combining the results from 3a and 3b in THF gave an Arrhenius function for hydrogen atom transfer from t-BuSH to primary radicals of log(k/M-1 s-1) = (8.37 +/- 0.08) - (2.00 +/- 0.09)/2.3RT; the calculated rate constant at 25 deg C is 8.0 * 106 M-1 s-1.This study ultimately relates the t-BuSH rate constants to those for hydrogen atom transfer to primary radicals from both Bu3SnH and PhSH and serves to compare the latter two sets of kinetic data; it also demonstrates that the fast radical clock reactions of 3a and 3b are calibrated against equivalent standards.
Synthesis and radiation sensitivity of phenoxazine type color formers including thiol ester protective group
Tachikawa, Tatsuya,Sato, Yohei,Tokita, Sumio
, p. 161/[461]-166/[466] (2007/10/03)
3,7-Bis(N,N-diethylamino)-10-(phenylthio)carbonylphenoxazine (1a) and its analogs (1b-f) were synthesized and the color change after γ irradiation was investigated. The color change of acetonitrile solutions of 1a ([1a] 0 = 1.0 × 10-3 M) after γ irradiation was identified by naked eyes at the dose of 20 Gy. Phenylthio-substituted compound la showed more significant absorbance increase than phenoxy-substituted compound, 3,7-bis(N,N-diethylamino)-10-phenoxycarbonylphenoxazine (2a). The C-S cleavage in la by γ irradiation was revealed to occur more easily than the C-O cleavage in 2a. The sensitivity of the color formers 1a-f) to γ rays was correlated with the stability of the thiyl radicals generated in the reaction.
Kinetics of Intramolecular Alkyl Radical Attack on Sulfur in Disulfides and Thioesters
Beckwith, Athelstan L. J.,Duggan, Sandhya A. M.
, p. 1509 - 1518 (2007/10/02)
The 4-(alkyldithio)butyl radicals 8a and c, and the 4-(phenyldithio)butyl radical 8b, generated from the corresponding esters of N-hydroxypyridine-2(1H)-thione, undergo fast exo-cyclisation by SHi attack at sulfur.Similarly, the 5-(alkyldithio)pentyl radical 8d undergoes 1,6-ring formation.The rate constants for cyclisation were determined by photolysis of the radical precursors in the presence of appropriate thiols.Butyl and pentyl radicals bearing ω-acetylthio or ω-benzoylthio substituents also undergo ring closure but much more slowly.The kinetics of these intramolecular SH2 reactions are discussed and compared with those for the intermolecular attack of hexyl radicals on diphenyl disulfide and on dibutyl disulfide.
Reactions of Triplet Carbenes with Sulfides and Disulfides: Ylide vs. Radical Formation
Alberti, A.,Griller, D.,Nazran, A. S.,Pedulli, G. F.
, p. 3024 - 3028 (2007/10/02)
The reactions between triplet diphenylcarbene and fluorenylidene with a variety of sulfides and disulfides were investigated with use of electron paramagnetic resonance (EPR) spectroscopy, laser flash photolysis, and product studies.Diphenylcarbene reacted with these substrates by a radical-like displacement mechanism.Rate constants were ca. 1E6 M-1 s-1, and the resulting thio-substituted diphenylmethyl radicals were identified by their EPR and optical spectra.By contrast, the analogous reactions of fluorenylidene had rate constants of 1E8-1E9 M-1 s-1 and proceeded by an ylide mechanism.Product studies were consistent with these results but were not sufficient in themselves to reveal these mechanistic differences.
