Pulse Radiolysis Studies. XVII. Reaction Kinetics of Molecular Cations of Aromatic Compounds in Dichloroethane Solution

Abstract

Fast reaction studies of the kinetics of molecular cations of aromatic molecules, formed by irradiation of the aromatic compounds in 1,2-dichloroethane solution, have provided quantitative information about the modes of formation and of decay of these molecule ions. Specific reaction rates have been determined for the electron transfer from a neutral aromatic molecule to an aromatic cation for three donor–acceptor pairs. The rate of formation of the aromatic cation, thought to be a charge transfer from the aromatic molecule to the solvent cation, is so high as to suggest that migration of the solvent cation is not a process of molecular diffusion, but involves an electron jump process in the solvent. The decay of the aromatic cation appears to be due largely to recombination with the counterion. Absolute rate constants for electron transfer between the aromatic pairs studied are at or near diffusion controlled, with values ranging from 5.1 × 109 to 9.9 × 109M−1·sec−1 at 25°C.

Formation and decay of the biphenyl cation radical in aqueous acidic solution

“…In these experiments the biphenyl cation radical was created by charge transfer from the solvent cation and some kinetic data have been reported. [1][2][3]6 The absorption spectrum of this cation radical is well established. It has absorption bands with maxima around 380 and 690 nm and a ratio of extinction coefficients of the two bands between 2 and 3.…”

Solute radical cation yields in the pulse radiolysis of solutions of aromatic amines in chlorinated hydrocarbons

“…CReceived June 7,1971) Publication costs assisted by Hahn-Meitner-Institut fur Kernforschung Ion yields and ion neutralization processes have been studied in pulse-irradiated acetone solutions using optical and conductivity methods. The yield of free (CH3)2CO" ions has been determined to be Gn = 1.20 ± 0.20 by conductivity measurements.…”

Fast reaction studies of carbanions and carbocations in solution

“…This work on carbanions and carbocations follows from our recent investigations, by the pulse radiolysis method, of aromatic radical anions19™21 and radical cations. 22,23 With this radiation chemical technique, the solvated electron, in various liquids, serves as the reducing species to form the anionic intermediates by electron attachment to selected solutes. In other solvents, such as chlorinated hydrocarbons, the solvent cation serves as the oxidizing species to form the cationic intermediate by electron transfer from selected solutes.…”