36877-87-9Relevant academic research and scientific papers
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.
One-Electron Oxidation of Alkylbenzenes in Acetonitrile by Photochemically Produced NO3.: Evidence for an Inner-Sphere Mechanism
Giacco, Tiziana Del,Baciocchi, Enrico,Steenken, Steen
, p. 5451 - 5456 (2007/10/02)
The reaction between NO3. and polyalkylbenzenes was studied using 308-nm laser flash photolysis of cerium(IV) ammonium nitrate in the presence of the alkylbenzenes in acetonitrile solution.For all benzenes, with the exception of monoalkylbenzenes and o- and m-xylene, the reaction with NO3. was found to yield the corresponding radical cations and to proceed in an apparently straightforward bimolecular manner.For monoalkylbenzenes and o- and m-xylene, radicals were seen which are derived from the parents by formal loss of H. from the side chain of the aromatic.This reaction proceeds via a complex between the aromatic and NO3. with the decomposition of the complex being rate determining at higher concentrations of aromatic (rate constants for decomposition between 6 * 105 and 4 * 107 s-1).In the complex, electron transfer from the aromatic to NO3. is suggested to be concerted with deprotonation of the incipient radical cation.Formation of a complex between NO3. and aromatics is likely even in those cases where radical cations are observed, with the assumption that in these cases the complex decomposition rate is greater than 6 * 107 s-1.
PHENYL RADICAL KINETICS.
Scaiano,Stewart
, p. 3609 - 3614 (2007/10/02)
The reactions of phenyl radicals with 17 substrates have been examined by using laser flash photolysis techniques. Absolute rate constants were determined for all the reactions in Freon 113 at 298 K by using iodobenzene or benzoyl peroxide as radical precursors. The following are some representative rate constants, which include all possible modes (or sites) of attack on each substrate: benzene, (4. 5 plus or minus 0. 3) multiplied by 10**5 M** minus **1 s** minus **1; chlorobenzene, (1. 18 plus or minus 0. 13) multiplied by 10**6 M** minus **1 s** minus **1; methyl methacrylate, (1. 8 plus or minus 0. 3) multiplied by 10**8 M** minus **1 s** minus **1; carbon tetrachloride, (7,8 plus or minus 0. 7) multiplied by 10**6 M** minus **1 s** minus **1; tetrahydrofuran, (4. 8 plus or minus 0. 6) multiplied by 10**6 M** minus **1 s** minus **1; toluene (1. 7 plus or minus 0. 7) multiplied by 10**6 M** minus **1 s** minus **1.
Liquid-Phase Pyrolysis of 1,2-Diphenylethane
Miller, R.E.,Stein, S. E.
, p. 580 - 589 (2007/10/02)
This paper presents results of a kinetic study of the deconposition of 1,2-diphenylethane in the liquid phase between 350 and 425 deg C along with a through mechanistic analysis of this system using thermochemical kinetics analysis and computer modeling.Toluene, trans-1,2-diphenylethene, and 1,1-diphenylethane are important products throughout the range of decomposition studied, with 1,2,3,4-tetraphenybutane being a major product in the early stages of reaction and diphenylmethane becoming important after extensive decomposition.Some noteworthy aspects of this reaction are the following: (1) all major product in the early stages of reaction can be quantitatively accounted for by a free-radical reaction model employing reasonable kinetic parameters; (2) trans-1,2-diphenylethene is formed by both a direct and indirect route involving α-1,2-diphenylethyl radicals; (3) 1,1-diphenylethane appears to be formed by a thermodynamically uphill 'neophyl' rearrangement; (4) above 10percent reaction secondary reactions lead to formation of diphenylmethane and noticeable divergence of predicted and observed product concentrations.This work presents the first use of thermochemical kinetics principles for analysis of complex liquid phase pyrolytic reactions and represents a first step toward establishing a reliable and self-consistent set of rate parameters for interpretation of these reactions.
