81372-23-8Relevant academic research and scientific papers
Photochemical properties of excited triplet state of 6H-purine-6-thione investigated by laser flash photolysis
Alam,Fujitsuka,Watanabe,Ito
, p. 1338 - 1344 (2007/10/03)
Photochemical reactions of 6H-purine-6-thione (PuT) via the excited triplet state [3(PuT)*] have been studied by means of laser flash photolysis in organic solvents. Transient absorption bands at 475 and 690 nm were assigned to 3(PuT)*. Intersystem quantum yield and the lowest triplet energy of 3(PuT)* were evaluated to be 0.99 and 63 kcal/mol, respectively. The self-quenching rate constant is quite large (2.3×109 M-1 s-1 in THF). In photoinduced electron transfer, 3(PuT)* acts as electron acceptor for tetramethylbenzidine, while 3(PuT)* acts as electron donor for p-dinitrobenzene. Rate constants for H-atom abstraction (khT) of 3(PuT)* from benzenethiols, tocopherol, and 1,4-cyclohexadiene are on the order of 108 M-1 s-1. From the Hammett plots of khT for substituted benzenethiols, a negative ρ value indicates that 3(PuT)* has electrophilic character. In the addition reaction of 3(PuT)* toward various alkenes, the electrophilic character of 3(PuT)* was also confirmed. By steady-light photolysis of PuT, purine was produced via 3(PuT)* after H-atom abstraction. On combination of these results, the character of the lowest 3(PuT)* was presumed.
Evaluation of dissociation energies of S-H bonds in thiophenols and thioalcohols on the basis of kinetic measurements
Denisov
, p. 238 - 241 (2007/10/03)
Kinetic data on the reactions of alkyl and benzyl radicals with thiophenol C6H5SH were analyzed within the framework of the parabolic model of transition state. The values of the parameter that establishes a correlation between the activation energy of a reaction and its enthalpy were calculated for reactions of alkyl and benzyl radicals with the C6H5SH. The equations of the parabolic model were used to calculate the bond dissociation energies for 11 thiophenols and 4 thioalcohols. The activation energies for reactions of 12 thiophenoxy radicals with cumene and of C6H5S? radical with several alkyl-aromatic hydrocarbons were obtained.
Substituent Effects on the Free-radical Addition Reactions of Arylthiyl Radicals with Arylacetylenes
Ito, Osamu,Fleming, Maria Daniela C. M.
, p. 689 - 694 (2007/10/02)
Absolute rate constants for addition reactions of arylthiyl radicals (YC6H4S.) to arylacetylenes (XC6H4CCH) have been determined by a flash-photolysis method.The rate constants (in dm3 mol-1 s-1) vary from 1.
Kinetic Study for Spin-Trapping Reactions of Thiyl Radicals with Nitroso Compounds
Ito, Osamu,Matsuda, Minoru
, p. 1937 - 1940 (2007/10/02)
The rate constants for the reactions of para-substituted benzenethiyl radicals with nitroso compounds have been determined by flash photolysis.For the benzenethiyl radical the rate constants (M-1 s-1) decreased in the order pentameth
