94089-33-5Relevant academic research and scientific papers
Solvent Effects in the Reactions of Peroxyl Radicals with Organic Reductants. Evidence for Proton-Transfer-Mediated Electron Transfer
Neta, P.,Huie, R. E.,Maruthamuthu, P.,Steenken, S.
, p. 7654 - 7659 (1989)
Absolute rate constants for the reaction of substituted methylperoxyl radicals with ascorbate, urate, trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) and TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine) have been determined by pulse radiolysis in different solvents.In water-alcohol or water-dioxane solutions, the rate constants for trihalomethylperoxyl radicals generally increase with increasing water content.The rate constant for the reaction of CCl3O2* radicals with trolox was measured in water, MeOH, i-PrOH, t-BuOH, ethylene glycol, diethyl ether, dioxane, acetone, acetonitrile, formamide, dimethylformamide, pyridie, and CCl4.The rate constants were found to correlate well with a two-parameter equation that includes the dielectric constant of the solvent and the coordinate covalency parameter, a measure of the proton-transfer basicity of the solvent.Kinetic isotope effects in H2O/D2O of about 2 and the activation entropies of about -10 eu for reduction of RO2* by the organic reductants indicate that electron transfer to the peroxyl radical is concerted with the transfer of proton from the solvent to the incipient hydroperoxide anion.
Perfluorobutylperoxyl Radical as an Oxidant in Various Solvents
Nahor, G. S.,Neta, P.,Alfassi, Z. B.
, p. 4419 - 4422 (2007/10/02)
Perfluorobutylperoxyl radicals were produced by pulse radiolysis of aerated solutions of perfluorobutyl iodide.The rate constants for reaction of this radical with several organic reductants, chlorpromazine, trolox, hydroquinone, and several other phenols, were determined in various solvents and were found to be in the range of 105 -109 M-1 s-1.By comparison with other haloalkylperoxyl radicals, C4F9OO. was found to be a much more powerful oxidant, whose reactions took place more rapidly and were less sensitive to solvent and substituent effects.The rate constants (k) for oxidation of a series of para-substituted phenols by C4F9OO. gave a good linear correlation between log k and the electrophilic substituent constant ?+, with a slope of ρ+ = -2.3, indicating formation of a positively charged transition state.Parallel experiments with CCl3OO. were limited to the most reactive phenols and gave a higher slope, ρ+ = -3.3.The rates of reaction of C4F9OO. with trolox and chlorpromazine were found to depend on solvent viscosity, but much less on solvent polarity and acid-base properties, probably because they were closer to the diffusion-controlled limit.The longer chain C10F21OO. was somewhat less reactive than C4F9OO. because of geometric factors.
Rate Constants for Reduction of substituted Methylperoxyl Radicals by Ascorbate Ions and N,N,N',N'-tetramethyl-p-phenylenediamine
Neta, P.,Huie, R. E.,Mosseri, S.,Shastri, L. V.,Mittal, J. P.,et al.
, p. 4099 - 4104 (2007/10/02)
Absolute rate constants (k) for reduction of substituted methylperoxyl radicals by ascorbate ions and by TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine) in aqueous solutions have been determined by pulse radiolysis.The rate constants vary from 1E6 to 1E9 M-1 s-1, increasing as the electron-withdraving capacity of the substituent on the peroxyl group increases.Linear correlations are observed between log k and the Taft substituents ?* for a wide variety of substituents, but not all substituents fit the same line.In the case of ascorbate as reductant, the points for peroxyl radicals that contain halogens on the α-carbon lie on a different line (ρ*=0.41) than that for the other substituents (ρ*=1.25).In the case of TMPD there are alsotwo families of peroxyl radicals: Those comprimising the electron-donating groups Me through t-Bu (ρ=5.6) and those containing electron-withdrawing substituents (ρ*=0.64).
