54737-34-7Relevant academic research and scientific papers
Free electron transfer from several phenols to radical cations of non-polar solvents
Ganapathi,Hermann,Naumov,Brede
, p. 4947 - 4955 (2007/10/03)
Electron-transfer reactions from phenols to parent radical cations of solvents were studied using pulse radiolysis. Phenols bearing electron-withdrawing, electron-donating and bulky substituents were investigated in non-polar solvents such as cyclohexane, n-dodecane, n-butyl chloride and 1,2-dichloroethane. The experiments revealed the direct, synchronous formation of phenoxyl radicals and phenol radical cations in all cases and in nearly the same relative amounts. This was explained by two competing electron-transfer channels which depend on the geometry of encounter between the parent solvent radical cations and the solute phenol molecules. The mechanism is analysed at a microscopic level, treating diffusion as a slow process and the local electron transfer as an extremely rapid event. Furthermore, the effect of various phenol substituents and solvent types on the electron-transfer mechanism and on the decay kinetics of the solute phenol radical cations was analysed. The results were further substantiated using a quantum chemical approach.
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.
One-Electron Redox Potentials of Phenols. Hydroxy- and Aminophenols and Related Compounds of Biological Interest
Steenken, S.,Neta, P.
, p. 3661 - 3667 (2007/10/02)
The rate constants for reversible electron transfer between a series of substituted phenolate ions and anilines and various substituted phenoxyl or anilino radicals in aqueous solution were measured by observing the formation or depletion of the radicals involved.Nonequilibrium concentrations of the radicals were produced in the presence of the corresponding phenols or anilines by using the pulse radiolysis technique.The relaxation of the system to equilibrium was monitored by optical detection methods.From the equilibrium constants for one-electron transfer, the one-electron redox potentials (E2) for 38 phenolic or anilino type compounds were determined, many of which are natural products.The redox potentials are strongly influenced by electron-donating or -withdrawing substituents at the aromatic system.
