12169-65-2Relevant academic research and scientific papers
Kinetic models for gas-phase electron-transfer reactions between nitrobenzenes
Han, Chau-Chung,Wilbur, James L.,Brauman, John I.
, p. 887 - 893 (1992)
Rate constants for gas-phase electron-transfer reactions between substituted nitrobenzenes have been measured using ion cyclotron resonance spectroscopy. On the basis of the assumption that these reactions occur through the formation of an intermediate complex, a statistical model is used to interpret the reaction kinetics. The intersecting parabolas quantum mechanical model provides an alternative description of the energy surface. Energy barriers are found to be consistent for the two methods. The results for exothermic reactions are consistent with a Marcus theory analysis, but suggest that a zero-order potential energy surface may not be completely adequate for quantitative prediction of reaction rates.
A Pulse Radiolytic Study of Aqueous Solutions Containing Nitrobenzene and Methylviologen
Nahor, Gad S.,Rabani, Joseph
, p. 5256 - 5260 (1985)
Solutions containing 2-propanol, nitrobenzene (NB), and methylviologen (MV2+) have been studied in wide ranges of concentrations and pHs.The two radicals NB- and MV+ are formed by the reactions of NB and MV2+, respectively, with both the hydrated electron and the 2-propanol radical.Studies were carried out at 578 nm where only the MV+ absorbs light.The decay of MV+ follows a single second-order process whose rate constant depends on , +>, and 2+>.Our findings could be explained by a fast equilibrium between the viologen and nitrobenzene redox systems followed by a slow reaction between MV+ and either NB- or its acidic form NBH.
Estimation of Rate Constants for Near-diffusion-controlled Reactions in Water at High Temperatures
Elliot, A. John,McCracken, David R.,Buxton, George V.,Wood, Nicholas D.
, p. 1539 - 1547 (1990)
Rate constants measured over the temperature range 20-200 deg C are reported for the following reactions: (a) reaction of the hydrated electron with oxygen, the proton, hydrogen peroxide, nitrate, nitrite, nitrobenzene and methyl viologen; (b) reaction of the hydroxyl radical with another hydroxyl radical and ferrocyanide; (c) reaction of the hydrogen atom with permanganante and oxygen.To evaluate methods of estimating rate constants at high temperatures these rate constants and others in the literature have been fitted to the following equation: kobs = kdiff/(1 + kdiff/kreact) where kobs is the measured rate constant for the bimolecular reaction in solution, kdiff is the encounter rate constant of the two reacting species, and kreact is the rate constant that would be measured if diffusion of the species was not rate influencing.With the exception of reactions of hydrated electron with nitrate and nitrite ions and nitrous oxide, good fits have been obtained to the above equation, and the results demonstrate that few, if any, of the reactions which are pertinent to water radiolysis are truly diffusion controlled at elevated temperatures.
Photocatalytic reduction of nitroorganics over illuminated titanium dioxide: Electron transfer between excited-state TiO2 and nitroaromatics
Ferry, John L.,Glaze, William H.
, p. 2239 - 2244 (2007/10/03)
The present study investigates the steady-state photocatalytic reduction of methyl viologen and a suite of monosubstituted nitrobenzenes. Reduction was carried out in deoxygenated, illuminated aqueous slurries of titanium dioxide (Degussa P25) in the presence of a sacrificial electron donor, 2-propanol. Langmuir-Hinshelwood plots were obtained for the reduction of each compound and found to be linear, with an average correlation of 0.98 and with a standard deviation on the correlations of 0.02. The concentration independent rates for nitroaromatic reduction obtained from these plots were normalized against the rate of methyl viologen reduction and the ratio was used to solve for the rate constant of nitroaromatic reduction, assuming a bimolecular model. The assumptions behind this procedure were tested by the use of the Marcus expression. Using the reorganization energy for the reaction as the fitting variable, it was possible to fit the measured rates to the predicted rates with a reorganization energy of 138 kJ/mol.
Resonance Electron Capture Rate Constants for Substituted Nitrobenzenes
Knighton, W. B.,Mock, R. S.,McGrew, D. S.,Grimsrud, E. P.
, p. 3770 - 3776 (2007/10/02)
We report here a new method for the determination of electron capture (EC) rate constants that utilizes a pulsed electron beam mass spectrometer.The method is first tested by measurements of the known dissociative electron capture rate constants for several halogenated methanes that have been extensively studied by other techniques.The resonance electron capture (REC) rate constants of nitrobenzene (NB) and 23 substituted nitrobenzenes (SNB's) are then determined for the first time at 125 deg C in 10 Torr of methane buffer gas.The SNB's studied here include several sets of closely related structural isomers whose electron affinities (EA's) have been previously determined.It is shown that the REC rate constants of these compounds bear little systematic relationship with the EA's of these compounds.The REC rate constants of the SNB's are also compared with other previously reported characteristics associated with the negative ionization of these compounds, including their entropies of negative ionization, the lifetimes against autodetachment of their initially formed molecular anions, and the rates of autodetachment from electronically excited states of their molecular anions.
A Linear Free Energy Relationship for an Equilibrium Isotope Effect
Stevenson, Gerald R.,Wehrmann, Glenn C.,Reiter, Richard C.
, p. 901 - 905 (2007/10/02)
The solution electron affinities of a series of monosubstituted phenyl-d5 benzenes relative to their perprotiated analogues were measured via electron paramagnetic resonance studies.The equilibrium constant for the electron transfer X-C6H5.- + X-C6D5 X-C6H5 + X-C6D5.-, where X = H, C6D5, CN, NO2, OCH3, tert-butyl, was found to be less than unity for all cases.However, this equilibrium constant is closer to unity for those systems where the substituent is electron withdrawing in nature, and it deviates further from unity for those systems that have an electron-donating group as the substituent.A linear free energy relationship was found, and the positive ρ value (0.34) is presumably due to the fact that there is a smaller excess charge and spin density from the antibonding electron in the area of the molecule where isotopic substitution takes place, for those systems where the ? value of the substituent is positive.
ESR Spectra of the Radical Anions of Nitrobenzene and p-Nitrobenzoic Acid Incorporated into Micelles
Kubozono, Yoshihiro,Aoyagi, Makoto,Ata, Masafumi,Gondo, Yasuhiko
, p. 3156 - 3161 (2007/10/02)
The radical anions of nitrobenzene and p-nitrobenzoic acid have prepared chemically for the first time in aqueous solutions with the aid of micelles.The radicals thus prepared are stable and the resulting ESR spectra are unsymmetrical owing to the suppressed rotational diffusion of the radicals due to incorporation into micelles.The environments surrounding the radicals are discussed in terms of the 14N hyperfine coupling constants and the rotational correlation times.For p-nitrobenzoic acid radical anion, the temperature dependence of the ESR spectrum has been studied.
Gas-Phase Ion-Molecule Reactions of the Nitric Oxide Anion
Rinden, Elizabeth,Maricq, M. Matti,Grabowski, Joseph J.
, p. 1203 - 1210 (2007/10/02)
The chemical reactivity of nitric oxide anion (NO(1-)) with a variety of organic neutrals at ambient energies and in argon bath gas has been probed using the flowing afterglow technique.The reactions fall into four main classes: electron transfer, dissociative electron transfer and/or displacement, collisional detachment, and clustering.Electron transfer can occur when the neutral reactant possesses a positive electron affinity greater than the electron affinity of NO., but does not always do so.Bimolecular substitution at sulfur is shown to occur with dimethyldisulfide, but for other substrates, distinguishing between displacement and dissociative electron transfer is not possible.Collisional detachment is the exclusive reaction channel observed for a few of the molecules examined and occurs to some extent with many of the neutrals tested.Cluster ion formation between NO(1-) and a number of the reactant neutrals which possess permanent dipole moments is observed.Additional pathways were observed for several of the neutrals examined.The collected observations are discussed in light of the general theory of ion-molecule reactions.
Eguilibrium Studies by Electron Spin Resonance. 17. The Effect of a Methyl Group on the Solution Electron Affinity of Nitrobenzene
Stevenson, Gerald R.
, p. 493 - 496 (2007/10/02)
Electron spin resonance studies have shown that the free energy of electron transfer from the ion-associated anion radical of nitrobenzene to p-methylnitrobenzene (PhNO2.-, Na+ + CH3-PhNO2 = PhNO2 + CH3-PhNO2.-,Na+) in liquid ammonia is 1.52 kcal/mol.The free energies of ion association for both anion radicals were measured, and these values were used in a thermochemical cycle to obtain the free energy of electron transfer involving the unassociated ions.This free energy of electron transfer is 1.4 kcal/mol, which is identical with the difference in the electron affinities of PhNO2 and CH3-PhNO2 in the gas phase.It was found that the ion association constant increased from 320 to 381 for PhNO2.- and from 380 to 450 for CH3-PhNO2.- when the solvent is changed from ammonia to methylamine.The increase in the ion association constant caused by placing a methyl group on the solvent is "coincidentally" the same as that caused by placing it on the nitrobenzene anion radical.
Electron Affinities of Di- and Tetracyanoethylene and Cyanobenzenes Based on Measurements of Gas-Phase Electron-Transfer Equilibria
Chowdhury, Swapan,Kebarle, Paul
, p. 5453 - 5459 (2007/10/02)
The electron affinities of tetracyanoethylene, trans-1,2-dicyanoethylene, and eleven substituted benzonitriles as well as two naphthonitriles were determined by measurement of the electron-transfer equilibria A-+B=A+B- with a pulsed electron high ion source pressure mass spectrometer.Rate constants for exothermic electron transfer involving the cyano compounds were found to be near unit collision efficiency.The EA (tetracyanoethylene)=3.17 eV obtained in the present work is considerably higher than the 2.3 eV photodetachment value of Palmer and Lyons.The electron affinities of benzene and benzonitrile substituted by CN, CHO, and NO2 increase in the given order, while the order for nitrobenzene is CHO, CN, NO2.This reversal of order is explained on the basis of a larger attenuation of the ?-withdrawing effect relative to the field effect of substituents when the electron density in the ?* single-electron orbital is decreased.
