34467-54-4Relevant academic research and scientific papers
RELATIVE ELECTRON AFFINITIES OF SUBSTITUTED BENZOPHENONES, NITROBENZENES, AND QUINONINES
Fukuda, Elaine K.,McIver, Robert T.
, p. 2291 - 2296 (1985)
The relative electron affinities of 53 molecules have been determined by measuring equilibrium constants for gas-phase electron-transfer reactions of the general type A-. + B = B-. + A.A pulsed ion resonance (ICR) spectrometer was utilized to generate, store , and detect molecular anion radicals at pressures below 1x1E5 torr.The ions were generated by electron capture and stored for several hundred milliseconds in a one-region ICR analyzer cell.A scale relative electron affinities has been constructed by using the mode of multiple overlaps.Substituent effects on the electron affinities of various nitrobenzenes, benzophenones, and quinones are discussed.
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.
Kinetic models for gas-phase electron-transfer reactions between nitrobenzenes
Han, Chau-Chung,Wilbur, James L.,Brauman, John I.
, p. 887 - 893 (2007/10/02)
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.
Entropy Changes and Electron Affinities from Gas-Phase Electron-Transfer Equilibria: A(-) + B = A + B(-)
Chowdhury, Swapan,Heinis, Thomas,Grimsrud, Eric P.,Kebarle, Paul
, p. 2747 - 2752 (2007/10/02)
By measuring the electron-transfer equilibria 1, A(-) + B = A + B(-), at 150 deg C with a pulsed electron high-pressure mass spectrometer we determined the ΔGo1 values involving 12 new compounds.Measurements of the temperature dependence of K1 for 21 reactions involving some of the new compounds and many compounds whose ΔGo1 had been determined previously led, via van't Hoff plots, to ΔHo1 and ΔSo1 values.These were interconnecting such that ΔHo and ΔSo continuous scales (ladders) were obtained.These were anchored to SO2 whose electron affinity is accurately known.Available geometries and vibrational frequencies for SO2 and SO2(-) permit the evaluation of So(SO2(-)) - So(SO2).Through the ΔSo scale the So(B(-)) - So(B) for the other compounds B could be obtained also.Certain regularities in the So(B(-)) - So(B) data permitted entropy estimates to be made also for compounds for which no van't Hoff plots were made.In this manner a table of ΔHo, ΔSo, and ΔGo data for the electron capture e + B = B(-) was obtained, which contains some 50 compounds B.Most of the compounds are substituted benzenes, quinones, conjugated acid anhydrides, and perfluorinated organics.
Electron Affinities from Electron-Transfer Equilibria : A(-) + B = A + B(-)
Grimsrud, Eric P.,Caldwell, Gary,Chowdhury, Swapan,Kebarle, Paul
, p. 4627 - 4634 (2007/10/02)
Determination of the equilibrium constants K1 for gas-phase electron-transfer equilibria with a pulsed electron beam high ion source pressure mass spectrometer led to the electron affinities of 34 compounds with EA's between 0.5 and 3eV.The compounds are mostly substituted nitrobenzenes, substituted quinones, and conjugated molecules containing oxygen atoms.The EA of smaller molecules like SO2, NO2, CS2, and CH3NO2 also were determined.The method is very well suited for rapid, accurate, routine determinations of electron affinities.A comparison with EA's determined with other gas-phase methods and EA's evaluated from polarographic half-wave reduction potentials and charge-transfer spectra in solution is made.The rate constants for a number of exothermic electron-transfer reactions were determined.Most of these proceed at near collision rates.Electron-transfer reactions involving perfluorinated compounds like perfluoromethylcyclohexane, perfluorocyclohexane, and sulfurhexafluoride do not follow this behavior.While the perfluoro compounds have high thermal electron capture cross sections, they do not accept electrons from A(-) of compounds A with lower electron affinity.The perfluoro anions do transfer electrons to compounds A with higher electron affinity, and the rate constants increase with EA(A) - EA(perfluoro compound).
