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A product and time-resolved kinetic studies provide insight into the role of structural effects on the one-electron oxidation of ring-methoxylated arylethanoic acids.

A laser flash photolysis study is carried out to assess solvent effects on the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals. The rearrangement rate constant k decreases by increasing solvent polarity and an excellent correlation with negative slope is obtained between log k and the solvent polarity parameter E(sub T)(super N).

A product and time-resolved kinetic study on the reactivity of tertiary arylcarbinyloxyl radicals bearing alpha-cyclopropyl and alpha-cyclobutyl groups is presented. It is proposed that in the transition state for beta-scission, formation of the C=O double bond is assisted by overlap with the C-C bonding orbitals of the cyclopropane ring.

The reactivity of the phthalimide-N-oxyl radical (PINO) toward the NO-methyl C-H bond of a number of 4-X-substituted N,N-dimethylanilines is investigated. It is found that the PINO is very reactive toward the methyl C-H bond of N,N-dimethylanilines promoting the oxidative N-demethylation of the substrate.

Ketyl radicals with lignin related structures are generated by means of radiation chemical and photochemical techniques. The high reactivity of ketyl radicals with oxygen coupled with the low rates of beta-fragmentation of the same species play an important role in the photoyellowing of lignin containing pulps and papers.

The direct functionalization of C(sp3)–H bonds represents one of the most investigated approaches to develop new synthetic methodology. Among the available strategies for intermolecular C–H bond functionalization, increasing attention has been devoted to hydrogen atom transfer (HAT) based procedures promoted by radical or radical-like reagents, that offer the opportunity to introduce a large variety of atoms and groups in place of hydrogen under mild conditions. Because of the large number of aliphatic C–H bonds displayed by organic molecules, in these processes control over site-selectivity represents a crucial issue, and the associated factors have been discussed. In this review article, attention will be devoted to the role of electronic effects on C(sp3)–H bond functionalization site-selectivity. Through an analysis of the recent literature, a detailed description of the HAT reagents employed in these processes, the associated mechanistic features and the selectivity patterns observed in the functionalization of substrates of increasing structural complexity will be provided. [ABSTRACT FROM AUTHOR]

Research has been conducted on the ring-methoxylate diarylmethane and diarylmethanol radical cations. The reactivities and properties of these compounds generated in aqueous solution via pulse and gamma-radiolysis have been investigated and the results of the studies are reported.

Research has been conducted on the ring-substituted cumyloxyl radicals. The spectral properties and beta-scission reactions of these radicals have been investigated via the laser flash photolysis study and the results are reported.

A study was conducted on the decay behavior of 1-(4-methoxyphenyl)-alkanol, (4-MeOC6H4CH(OH)R, R=H, alkyl) radical cations in aqueous solution. It reports on the results of a pulse radiolysis analysis of radical cations generated from 2-, 3-, and 4-(4-methoxyphenyl)-alkanols where the OH group is separated from the aromatic ring by an increasing number of carbon atoms. Among other findings, the intermediacy of an oxyl radical is suggested for the base-catalyzed decay of 3-(4-methoxyphenyl)-propanol radical cation.

The reduction potential of the radical cation of veratryl alcohol (3,4-dimethoxybenzyl alcohol), VA(super *+), was investigated using electron-transfer equilibration. The radical cation was produced in aqueous solution with SO(sub 4)(super *-). Experimental results showed that the reduction potential of VA(super *+) was 1.36 plus or minus 0.01 V/NHE. The radical cation undergoes a C-H deprotonation reaction from the side chain, resulting in an alpha-hydroxybenzyl-type radical.

The one-electron oxidation of several 1-arylpropanols, 1,2-diarylethanols and some of their methyl ethers by potassium 12-tungstocobaltate(III) in aqueous acetic acid is investigated. The oxidation process is subjected to kinetic and product analysis as well as pulse radiolysis experiments. Results provide additional information on the effects of structure upon the competition between carbon-carbon and carbon-hydrogen bond cleavage and the role of the side-chain OH groups in the cleavage of the carbon-carbon bond.

A study of the kinetics of side-chain oxidation of alpha-substituted 4-methoxytoluenes by K5(CoW12O40).11H2O in AcOH/H2O reveals that the reaction rate is affected by electron transfer and radical cation deprotonation processes. The kinetic examination has facilitated the estimation of values of K and the rate constant for the electron transfer process.