41071-23-2Relevant academic research and scientific papers
Solid state generation of phenoxyl radicals through β-fragmentation from specifically designed diazenes. An ESR investigation
Dol, Cyrielle,Bertrand, Michèle P.,Gastaldi, Stéphane,Besson, Eric
, p. 7744 - 7748 (2016)
Upon irradiation at room temperature, symmetrical diazene precursors enabled the formation of phenoxyl radicals through β-fragmentation reaction in the solid state. This traceless generation of phenoxyl radicals was investigated by ESR. This study showed that although the fragmentation of β-phenoxy radicals is a slow process in solution, it could be useful in solid state thanks to the absence of faster competitive pathways.
Direct Irradiation of Phenol and Para-Substituted Phenols with a Laser Pulse (266 nm) in Homogeneous and Micro-heterogeneous Media. A Time-Resolved Spectroscopy Study
Siano, Gastón,Crespi, Stefano,Bonesi, Sergio M.
, p. 14012 - 14025 (2020/11/20)
Direct irradiation of para-substituted phenols under N2 atmosphere in homogeneous (cyclohexane, acetonitrile, and methanol) and micellar (SDS) solution was investigated by means of time-resolved spectroscopy. After a laser pulse (266 nm), two transient species were formed, viz. the para-substituted phenol radical-cations and the corresponding phenoxy radicals. The radical-cations showed a broad absorption band located between 390 and 460 nm, while the phenoxy radicals showed two characteristic bands centered at 320 nm and 400-410 nm. The deprotonation rate constant of radical-cations (kH) of 105 s-1 and the reaction rate constant of the phenoxy radicals (kR) in the order of 109-1010 M-1·s-1 have been derived. The kH rate constants gave good linear Hammett correlation with positive slope indicating that electron-withdrawing substituents enhance the radical-cation acidity. The binding constants (Kb) of the para-substituted phenols with the surfactant were also measured, and NOESY experiments showed that phenols were located in the hydrophobic core of the micelle. Finally, computational calculations provided the predicted absorption spectra of the transients and nice linear correlations were obtained between the theoretical and experimental energy of the lower absorption band of these species.
Localized electron transfer in nonpoiar solution: reaction of phenols and thiophenols with free solvent radical cations
Brede, Ortwin,Ganapathi, Mahalaxmi R.,Naumov, Sergej,Naumann, Wolfgang,Hermann, Ralf
, p. 3757 - 3764 (2007/10/03)
Free electron transfer (FET) is understood as the reaction of free and uncorrelated solvent parent radical cations with solutes characterized by a lower ionization potential than those of the solvent. We studied electron transfer from phenols and thiophen
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.
The one-electron reduction potential of 4-substituted phenoxyl radicals in water
Lind,Shen,Eriksen,Merényi
, p. 479 - 482 (2007/10/02)
By means of pulse radiolysis the one-electron reduction potentials of twelve 4-substituted phenoxy radicals have been determined. The main reference used was the ClO2./ClO2- couple. By combining the redox potentials of phenoxyl radicals with the aqueous acidities of phenols the bond strength of the phenolic O-H bond was calculated. These values were found to be in good agreement with O-H bond dissociation enthalpies measured in the gas phase.
Reaction of tert-Butoxy Radicals with Phenols. Comparison with the Reactions of Carbonyl Triplets
Das, P. K.,Encinas, M. V.,Steenken, S.,Scaiano, J. C.
, p. 4162 - 4166 (2007/10/02)
Tert-butoxy radicals generated in the photodecomposition of di-tert-butyl peroxide react efficiently with phenols to yield the corresponding phenoxy radicals.Typical rate constants in benzene at 22 deg C are 3.3x108 and 1.6x109 Msup
