Low-temperature pulse radiolysis. II. Time-dependent spectra of anions of aromatic ketones

Abstract

Using a pulse radiolysis technique the absorption spectra of anions of acetophenone, benzophenone, and their derivatives have been observed in ethanol at 100°K. The spectra obtained immediately after the 0.5-Msec pulse shift toward shorter wavelengths within about 200 Msec. The subsequent spectra are in good accord with those observed for the anions produced by steady y radiolysis at 77°K. These results indicate that reorientation of solvent molecules around the anion is responsible for the spectral shift in protic solvents. The spectra observed immediately after the pulse are due to the presolvated anions, and the subsequent spectra to the solvated ones. The temperature dependence of the decay of the presolvated benzophenone anion was also studied.

Electron capture in .gamma.-irradiated 2-methyltetrahydrofuran glasses containing two solutes at 77 K

“…This finding suggests that the spectrum in the MTHF glass may be assigned to presolvated BQ anions, as in the case of benzophenone anions. 26 The present spectrum of the NQ anion may also be assigned to a presolvated form, though other data are not available for comparison. However, whether these anions are solvated or not does not affect the discussion and conclusion of the present study.…”

Kinetics and mechanism of the reactions of the superoxide ion in solutions. I. Absorption spectra and interaction with solvents and cations

“…However, the direction of the shift is unexpected, because the solvation of radical anions by proton donors results as a rule in the shift of absorption maxima toward the short-wave region [25,26], as is observed for the spectra of 0; in neat solvents (Table I). It is possible that the observed effect is accounted for by the formation of mixed solvated complexes O;(HX),(DMF), (HX = HzO or EtOH).…”

Antiaromaticity-promoted radical anion stability in α-vinyl heterocyclics

“…9 Unlike neutral radicals, the lifetime of the radical anions is determined not only by the structure but also by the medium, as it prefers to react with oppositely charged particles to form ionic aggregates. 10 When a radical anion is stabilized by the conjugation effect (such as the naphthalene radical anion) or a large hindrance (such as the benzophenone radical anion), 11,12 it has a long lifetime, whereas the relatively low temperature also prevents the radical anion from cleaving into two fragments. Electron spin resonance spectroscopy (ESR) 13 is an analytical technique that can characterize radical anion species.…”