34473-10-4

Upstream product

• 2348-46-1 ethanol radical 
• 100-17-4 para-methoxynitrobenzene 
• 85540-96-1 carbon dioxide anion radical 
• 5131-95-3 2-hydroxy-2-propyl radical 

Relevant academic research and scientific papers

Photoreduction of 4-substituted nitrobenzenes by amines

The reduction of several nitrobenzenes bearing electron-donor and electron-withdrawing substituents in the 4-position by triethylamine in acetonitrile was studied by cyclic voltammetry, EPR spectroscopy, and steady-state photolysis. The electrochemical re

Entropy Changes and Electron Affinities from Gas-Phase Electron-Transfer Equilibria: A(-) + B = A + B(-)

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 of Di- and Tetracyanoethylene and Cyanobenzenes Based on Measurements of Gas-Phase Electron-Transfer Equilibria

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.

One-Electron Reduction of Nitrobenzenes by α-Hydroxyalkyl Radicals via Addition/Elimination. An Example of an Organic Inner-Sphere Electron-Transfer Reaction

The reaction in aqueous solution of α-hydroxyalkyl radicals with para-substituted nitrobenzenes were studied by using product analysis, electron spin resonance, and pulse radiolysis techniques.At neutral pH the α-hydroxyalkyl radicals are quantitatively oxidized to yield the corresponding ketones or aldehydes and H+, and the nitrobenzenes are reduced to the radical anions.The mechanism of this redox reaction depends strongly on the substituents on the α-hydroxyalkyl radical (the electron donor) and on the nitrobenzene (the electron acceptor).In case of α-hydroxymethyl radical, the reaction proceeds by addition to the nitro group to produce an alkoxynitroxyl radical which can undergo an OH--catalyzed heterolysis to give formaldehyde and the radical anion of the nitrobenzene.With the α-hydroxyethyl radical, both addition and "electron transfer" take place, the fraction of electron transfer increasing with increasing electron-withdrawing power of the substituent.The nitroxyl-type adducts undergo a spontaneous unimolecular heterolysis to give acetaldehyde, H+, and nitrobenzene radical anion.The rate constants ks (from 2 to 5*104 s-1) for this heterolysis increase with increasing electron-withdrawing strength of the substituent if it is on the benzene, and they decrease if the substituent is on the methyl carbon of the nitroxyl.The heterolysis reaction is characterized by low (5-10 kcal/mol) activation enthalpies and strongly negative (-5 to -25 eu) activation entropies, which originate from hydration of a proton in the transition state.From the effect on the activation parameters exerted by substituents on the electron acceptor and on the electron donor parts of the nitroxyl radical it is concluded that the heterolysis reaction proceeds by a push-pull mechanism and is entropy controlled.In the α-hydroxyprop-2-yl radical with substituted nitrobenzenes, the lifetimes of potential adducts of the nitroxyl type are s=2.1*103 s-1.The heterolysis reaction can also be slowed down by making the solvent less polar than water: in 95percent propan-2-ol/5percent water ks=1.5*104 s-1 for R=CN as compared to >106 s-1 in water.