Electron spin resonance studies. Part 71. Side-chain oxidation pathways in the reactions of ˙OH and SO₄^–˙ with some phenyl-substituted carboxylic acids, their anions, and some related compounds

Abstract

A series of arene radical-cations has been generated in situ by the reactions of methylbenzene, phenylethanoic acid, 3-phenylpropanoic acid, and some derivatives and cyclic analogues with both SO4-* and *OH (the latter in acid solution). The results are interpreted in terms of a variety of subsequent rapid reactions including hydration, deprotonation (to give benzylic radicals), and fragmentation (decarboxylation): for a series of radical-zwitterions +'Ar( CH,),CO;( n = 1-3) decarboxylation (k 3 lo9 dm3 mo1-l s-l) appears t o proceed via direct intramolecular electron-transfer, though in some cases formation of a discrete o-bonded intermediate cannot be ruled out.

Photoinduced Decarboxylative Benzylation of Phthalimide Triplets with Phenyl Acetates: a Mechanistic Study

“…For nonbenzophenone type 2-arylacetic acids, i.e., phenylacetic acids lacking an aroyl substituent, a different decarboxylation pathway is operative. Previous spectroscopic studies have shown that phenylacetic acids undergo fragmentation in aqueous media upon addition of sulfate radical anions or hydroxyl radicals as well as upon direct biphotonic ionization at λ = 248 nm, thus yielding benzyl radicals. − This radical pathway was further confirmed in earlier studies on the photoinduced electron transfer (PET) of phenylacetic acids with acridine. , …”

Catalyst‐Free Photoredox Addition–Cyclisations: Exploitation of Natural Synergy between Aryl Acetic Acids and Maleimide

“…Precedent for such an internal SET exists; the research group of Young reported that during the reaction of SO 4 .− and a series of phenyl-substituted carboxylic acids an electron transfer took place from the carboxylate functional group to an aromatic radical cation or an intermediate species. [ 54 ]…”

Generation of radical-cations from naphthalene and some derivatives, both by photoionization and reaction with SO4–˙: formation and reactions studied by laser flash photolysis

“…The dimer radical-cation expectedt7 to result from the reaction of the radical-cation with parent, was directly detected in experiments in which the photomultiplier was replaced as a detector by a photodiode (to provide the greater sensitivity needed to detect absorptions at higher wavelength, e.g. 1 100 nm, see Figure 6). The broad band at CQ.…”