2122-46-5Relevant academic research and scientific papers
Phenolic hydrogen abstraction by the triplet excited state of thiochromanone: A laser flash photolysis study
Ribeiro, Alessandra M.,Bertoti, Ada Ruth,Netto-Ferreira, Jose? Carlos
, p. 1071 - 1076 (2010)
Triplet ketones are known to oxidize biological substrates which can lead to damage of several biomolecules such as amino acids, nucleosides and DNA. As part of our systematic study on the interaction between carbonyl compounds and phenols, the triplet reactivity of thiochromanone (1) towards substituted phenols, in acetonitrile, was investigated employing the laser fash photolysis technique. The quenching rate constants ranged from (1.1 ± 0.1) × 108 L mol-1 s-1 (4-cyanophenol) to (5.8 ± 1.0) × 109 L mol-1 s-1 (hydroquinone). A Hammett plot for the reaction of triplet 1 with phenols containing polar substituents resulted in a reaction constant ρ =-0.90. This negative value observed for the reaction constant ρ is in accord with a mechanism in which the hydrogen transfer from phenols to the triplet carbonyl involves a coupled electron/proton transfer.
Rate Constants for Reactions of Iodine Atoms in Solution
Alfassi, Z. B.,Huie, R. E.,Marguet, S.,Natarajan, E.,Neta, P.
, p. 181 - 188 (1995)
Laser flash photolysis (at 248 or 308 nm) of aryl iodides in water or water/methanol solutions produces iodine atoms and phenyl radicals.Iodine atoms react rapidly with added I- to form I2- but do not react rapidly with O2 (k = 10s
Pathways and kinetic energy disposal in the photodissociation of nitrobenzene
Galloway, Douglas B.,Bartz, Jeffrey A.,Huey, L. Gregory,Crim, F. Fleming
, p. 2107 - 2114 (1993)
Vacuum-ultraviolet photoionization molecular-beam mass spectrometry is a means of identifying primary photodissociation products and determining their recoil energies.At several photolysis wavelengths between 220 and 320 nm, we have observed three primary photodissociation pathways for nitrobenzene.Two of the pathways are C6H5NO2 C6H5 + NO2 and C6H5NO2 C6H5NO + O.The third pathway produces NO by one or both of the processes C6H5NO2 C6H5O + NO and C6H5NO2 C5H5 + CO + NO.The relative yield of the pathways producing NO2 and NO varies strongly with the photolysis wavelength.The production of NO2 exceeds that of NO by about 50percent for the 280 nm photolysis, but increases to almost a sixfold excess in 222 nm dissociation.The second pathways has a threshold energy that is about 0.50 eV greater that the thermodynamic limit for the formation of nitrosobenzene (C6H5NO) and an oxygen atom from nitrobenzene, probably reflecting the energy required to produce triplet nitrosobenzene and, perhaps, a barrier to dissociation on the triplet surface.The distribution in arrival times for a fragment provides an estimate of the recoil energy at each photolysis wavelength in these experiments.The channel producing nitric oxide (NO) radicals releases a relatively large amount of kinetic energy.Assuming the channel producing nitric oxide (NO) also produces phenoxy (C6H5O), we calculate a linear increase in kinetic energy from 0.29 eV at 320 nm to 1.1 eV at 220 nm.By contrast, the other two channels release only a small amount of kinetic energy (ca. 0.1 eV) at all wavelengths.An impulsive model does not describe the observed kinetic energy release for these low energy channels, suggesting that the energy release is more nearly statistical.The recoil energy predicted by an impulsive model for the channel producing nitric oxide and phenoxy radicals is closer to the observed kinetic energy release.
Laser flash photolysis study of the photochemistry of thioxanthone in organic solvents
Rodrigues, Janaina F.,De Assis Da Silva, Francisco,Netto-Ferreira, Jose? Carlos
, p. 960 - 965 (2010)
The photoreactivity of the triplet excited state of thioxanthone (TX) was investigated employing the laser fash photolysis technique. The wavelength for the absorption maximum and the lifetime of the triplet excited state are solvent dependent. When hydrogen donor solvents were employed, a new band at 410 nm was observed in the triplet absorption spectrum, which was attributed to the ketyl radical derived from thioxantone. Quenching rate constants, kq, ranged from (1.7 0.1) × 106 L mol-1 s-1 for toluene to ca. 109 L mol-1 s-1 for phenol and its derivatives containing polar substituents, as well as for indole, triethylamine and DABCO.
Iodine Atoms and Iodomethane Radical Cations: Their Formation in the Pulse Radiolysis of Iodomethane in Organic Solvents, Their Complexes, and Their Reactivity with Organic Reductants
Shoute, Lian C. T.,Neta, P.
, p. 4411 - 4414 (1991)
Pulse radiolysis of iodomethane in various organic solvents leads to formation of iodine atoms or iodomethane radical cations, which in turn form complexes with iodomethane or with the solvent.Radiolysis in cyclohexane gives CH3I*I, which exhibits an absorption peak at 390 nm, whereas radiolysis in benzene forms the solvent complex, C6H6*I, which exhibits an intense broad absorption centered at 490 nm.Radiolysis of iodomethane in acetone, benzonitrile, and halogenated hydrocarbons results in formation of the radical cation CH3I.+.In the former two solvents, this species forms a complex with another molecule of iodomethane to give (CH3))2+, which absorbs at 420 nm, in agreement with previous results in aqueous solutions, but in halogenated hydrocarbons it forms complexes with the solvents, absorbing at 320-360 nm, i.e. near the absorption of monomeric CH3I.+ in water.Complexes of I atoms oxidize phenol and triphenylamine relatively slowly whereas complexes of CH3I.+ react more rapidly.The reactivity of the CH3I.+*RX complexes increases in the order of RX = CH2Cl2, CHCl3, CH2Br2, CCl4, CH3I, and for each complex the reactivity with phenol increases with increase in electron donating power of substituents.Replacing the methyl group of iodomethane radical cation with ethyl or isopropyl decreases the reactivity, whereas trifluoromethyl increases the reactivity.These oxidation reactions proceed via an intermediate complex between the iodine species and the organic reductant.
One-electron transfer in electrochemical oxidation of calix[4]resorcinolarenes and their aminomethylated derivatives
Yanilkin,Ryzhkina,Morozov,Enikeev,Burilov,Kudryavtseva,Konovalov
, p. 373 - 378 (2001)
Calix[4]resorcinolarenes in the presence of amine and aminomethylated calix[5]resorcinolarenes in DMF undergo similar multistage electrochemical oxidation. The first stage proceeds at low potentials and involves reversible one-electron transfer with forma
Concerted proton-electron transfers. consistency between electrochemical kinetics and their homogeneous counterparts.
Costentin, Cyrille,Hajj, Viviane,Louault, Cyril,Robert, Marc,Saveant, Jean-Michel
, p. 19160 - 19167 (2011)
The concerted proton-electron transfer (CPET) oxidation of phenol with water (in water) and hydrogen phosphate as proton acceptors provides a good example for testing the consistency of the electrochemical and homogeneous approaches to a reaction, the com
Structure and infrared spectrum of 2-hydroxyphenyl radical
Nagata, Mitsuhiro,Futami, Yoshisuke,Akai, Nobuyuki,Kudoh, Satoshi,Nakata, Munetaka
, p. 259 - 264 (2004)
Infrared spectrum of 2-hydroxyphenyl, ·C 6H4-OH, produced from 2-iodophenol in a low-temperature argon matrix upon UV irradiation (λ>280 nm) was measured with an FT-IR spectrophotometer. This radical was found to be less stable by 120 kJ mol -1 than phenoxyl, C6H5-O·, by a density functional theory calculation. Two final photoproducts were identified as cyclopentadienylidenemethanone and 4-iodo-2,5-cyclohexadienone in analogy with the photoproducts of 2-chloro and 2-bromophenols. A kinetic analysis shows that the latter is produced via 2-hydroxyphenyl by hydrogen migration and iodine recombination while the former is produced by Wolff rearrangement after elimination of hydrogen iodide.
Solvents Effects in the Hydrogen Abstractions by tert-Butoxy Radical: Veracity of the Reactivity/Selectivity Principle
Kim, Sung Soo,Kim, Sung Yeon,Ryou, Seung Sin,Lee, Choon Seung,Yoo, Kwang Hee
, p. 192 - 196 (1993)
The Hammett correlations and primary deuterium kinetic isotope effects were obtained to investigate the solvent effects on hydrogen abstractions from thiophenols, phenols, and toluenes by tert-butoxy radical, where the latter proved to be a more sensitive probe than the former.The limitations of the reactivity/selectivity principle are discussed in terms of either anti-Hammond effects or Marcus theory and attributed to the duality in substituent (solvent) effects.While the polar transition states for the homolytic reactions should invite dual substituent effects, the dual solvations of tert-butoxy radical could trigger the dualism of solvent effects.The influence on the rates in general may dwindle in the order of structure > substituent > solvent.
Chemical Behavior of SO3- and SO5- Radicals in Aqueous Solutions
Huie, Robert E.,Neta, P.
, p. 5665 - 5669 (1984)
The chemistry of the radicals SO3- and SO5- has been investigated by using pulse radiolysis with kinetic spectrophotometry.Rate constants for the oxidation by SO3- of a variety of organic compounds were measured and equilibrium constants determined for the reactions of SO3- with chlorpromazine and phenol.SO3- was found to be a mild oxidant with a redox potential of E(SO3-/SO32-) = 0.63 V (vs.NHE) at pH>7 and E(SO3-/HSO3-) = 0.84 V at pH 3.6.The reaction of SO3- with O2 was shown to produce SO5-.The oxidation of several compounds by SO5- was found to occur more rapidly than their oxidation by SO3-.E(SO5-/HSO3-) was estimated to be approximately 1.1 V at pH 7.
