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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.

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.

The intra- and intermolecular kinetic deuterium isotope effects and the effects of substituents on reactivity were determined to study the mechanistic dichotomy in the oxidative N-dealkylation of a series of N,N-dimethylanilines catalyzed by tetrakis(pentafluorophenyl)porphyrin iron(III) chloride. The findings clearly showed the validity of the kinetic deuterium isotope effect profile criterion to distinguish electron transfer from the hydrogen atom transfer mechanism in the oxidative N-dealkylation of N,N-dimethylanilines.

A time-resolved kinetic study is used for analyzing the reactions of the tert-butoxyl (t-Bu[O.sup..]), cumyloxyl (Cum[O.sup..]), and benzyloxyl (Bn[O.sup..]) radicals with alkylferrocenes in solution. The studies have shown that both Bn[O.sup..] and Cum[O.sup..] have reacted with the ferrocene donors with rate constants that are in all cases higher than those measured for t-Bu[O.sup..], wherein the radical is well-localized.

The reaction of the benzotriazole N-oxyl radical (BTNO) with a series of 4-X-N,N-dimethylanilines (X = CN, C[F.sub.3], C[O.sub.2]C[H.sub.2]C[H.sub.3], C[H.sub.3], O[C.sub.6][H.sub.5], OC[H.sub.3]) is examined in C[H.sub.3]CN. The results are interpreted based on the electron-transfer mechanism from the N,N-dimethylanilines to the BTNO radical followed by deprotonation of the anilinium radical cation (ET-PT mechanism).

A kinetic study is carried out on one-electron oxidation of a series of substituted ferrocenes by the benzotriazole-N-oxyl radical (BTNO) and of ferrocene (FcH) by a series of ring-substituted benzotriazole-N-oxyl radicals in C[H.sub.3]CN. The relative reactivity of PINO and BTNO radicals have represented a criterium to help in the distinction of ET and HAT reactions promoted by these transients N-oxyl radicals.

The Ti[O.sub.2] photocatalyzed oxidation of cis-2-methylcyclopentyl phenyl sulfoxide in the presence of [Ag.sub.2]S[O.sub.4] in MeCN/[H.sub.2]O has formed 1-methylcyclopentanol, 1-methylcyclopentyl acetamide and phenyl benzenethiosulfonate as the main reaction products. The studies have shown that the C-S heterolysis in the radical cation is a unimolecular process that has led to an ion radical pair.

A combination of steady-state irradiation and nanosecond laser flash photolysis under nitrogen in MeCN is employed to study the 3-cyano-N-methylquinolinium perchlorate photosensitized oxidation of phenyl alkyl sulfoxides. The heterolytic C-S bond cleavage in the sulfoxide radical cations is shown to lead to the formation of several products, including alcohols and acetamides.

A kinetic study of the N-demethylation reaction of a number of 4-X-substituted-N,N-dimethylanilines (where X = OMe, OPh, C[H.sub.3], H) promoted by 2,2-diphenyl-1-picrylhydrazyl radical (dpph*) in MeCN is reported. The reaction obtained provides insight into the single-step hydrogen transfer mechanism from the N-C-H bond to dpph* which might take the form a concerted proton-electron transfer (CPET).

The C-heteroatom cleavage reactions of substituted dibenzyl sulfides and substituted dibenzylcyclohexylamines promoted by singlet oxygen in MeCN are examined. The reaction with singlet oxygen has led to an exciplex undergoing an intracomplex hydrogen atom transfer to produce a radical pair.

Kinetic studies are carried out on one-electron oxidation of a series of ferrocenes by phthalimide-N-oxyl radical (PINO) generated in C[H.sub.3]CN by reaction of N-hydroxyphthalimide (NHPI) with the cumyloxyl radical. The intrinsic reactivity of PINO in electron-transfer reactions is calculated from the Marcus cross relation and self-exchange rates of ferrocene and dimethylferrocene.

The kinetic and product study is performed on the reactions of chlorpromazine, N-methylphenothiazine, and N-ethylphenothiazine with singlet oxygen in MeOH and MeCN. A mechanism is proposed for the reaction of chlorpromazine where the first step has involved an interaction between singlet oxygen and the side-chain dimethylamino nitrogen.

A study reports information on spectral properties and the structure of aryl methyl sulfoxide radical cations, using pulse radiolysis and laser flash photolysis techniques. In water, the radical cations of 4-X'C6H4SOMe generated by pulse radiolysis at pH 4, present an intense absorption in the ultraviolet region and a broad less intense band in the visible region whose position depends on the nature of the ring substituent.

A product and time-resolved kinetic study of the effect of ring substitution on the reactivity of 1,1-diarylalkoxyl radicals are carried out. The radicals undergo an O-neophyl shift to give the isomeric 1-aryl-1-aryloxyalkyl radicals from which the corresponding aromaticketones are formed.

The absolute rate constants for beta-scission of a series of benzocycloalken-1-oxyl radicals and of the 2-(4-methylphenyl) -2-butoxyl radical are measured directly by laser flash photolysis. The benzocycloalken -1-oxyl radicals undergo ring opening with rates, which parallel the ring strain of the corresponding cycloalkanes.

The reactivity of the phthalimide N-oxyl radical (PINO) toward the OH bond of a series of substituted phenols is kinetically investigated in CH3CN. Further, the reaction selectivity and the deuterium kinetic isotope effect are determined.

A systematic product study was conducted for the beta-scission reactions of an extended series of 1-alkylcycloalkoxyl radicals, where both the ring size and the nature of the alkyl group were varied. The results demonstrate that regioselectivity is governed by the release of ring strain associated to ring opening and stability of the alkyl radical formed by C--R cleavage.

The experiment carried out to know the kinetic and product study of the aerobic oxidation of primary and secondary benzylic alcohols is presented. It was catalyzed by aryl-substituted N-hydroxyphthalimides.

The study of H2O2-promoted oxidations of the two nonphenolic beta-O-aryl lignin model trimers 1 and 2, catalyzed by lignin peroxidase (LiP) at pH = 3.5, is described. The results are compared with the genuine one-electron oxidant potassium 12-tungstocobalt(III)ate.

The photoinduced electron transfer reaction of bis(4-methoxyphenyl)methane sensitized by chloranil in MeCN was investigated. Homolytic and heterolytic carbon-hydrogen bond cleavage in alkylaromatic radical cations was also examined. Experimental results showed for the first time that an alkylaromatic radical cation undergoes homolytic breaking of the C(alpha)-H bond when it reacts with chloranil in MeCN and that the significant spin density on the oxygen atoms probably plays an important role in this process.

The reaction of 4-methoxycumyl alcohol (MCA) radical cation in acidic and basic solutions was investigated. The radical cation of MCA was formed by pulse radiolysis in water utilizing SO4*- or Tl2+ as the oxidant. For the first time, direct evidence was acquired indicating that 1-arylkanol radical cations can be deprotonated at the OH group to finally produce a highly reactive alkoxyl radical.

Previous research has shown that horseradish peroxidase (HRP) can catalyze the oxidation of sulfides to sulfoxides by a process involving the transfer of ferryl oxygen to the S atom. Given other findings that HRP does not transfer the ferryl oxygen to the substrates during oxidation, this result has caught the attention of many scientists. Two mechanisms that seek to explain how HRP can transfer the ferryl oxygen to the S atom during oxidation are presented.