Fenton's reagent revisited

ion from the Sugar Moiety Wendy Knapp Pogozelski† and Thomas D. Tullius*,‡ Department of Chemistry, State University of New York at Geneseo, Geneseo, New York 14454, and Department of Chemistry, Boston University, Boston, Massachusetts 02215 Received August 27, 1997 (Revised Manuscript Received February 26, 1998)

Oxidative Strand Scission of Nucleic Acids: Routes Initiated by Hydrogen Abstraction from the Sugar Moiety.

Lignin is the most abundant renewable source of aromatic polymer in nature, and its decomposition is indispensable for carbon recycling. It is chemically recalcitrant to breakdown by most organisms because of the complex, heterogeneous structure. The white-rot fungi produce an array of extracellular oxidative enzymes that synergistically and efficiently degrade lignin. The major groups of ligninolytic enzymes include lignin peroxidases, manganese peroxidases, versatile peroxidases, and laccases. The peroxidases are heme-containing enzymes with catalytic cycles that involve the activation by H2O2 and substrate reduction of compound I and compound II intermediates. Lignin peroxidases have the unique ability to catalyze oxidative cleavage of C-C bonds and ether (C-O-C) bonds in non-phenolic aromatic substrates of high redox potential. Manganese peroxidases oxidize Mn(II) to Mn(III), which facilitates the degradation of phenolic compounds or, in turn, oxidizes a second mediator for the breakdown of non-phenolic compounds. Versatile peroxidases are hybrids of lignin peroxidase and manganese peroxidase with a bifunctional characteristic. Laccases are multi-copper-containing proteins that catalyze the oxidation of phenolic substrates with concomitant reduction of molecular oxygen to water. This review covers the chemical nature of lignin substrates and focuses on the biochemical properties, molecular structures, reaction mechanisms, and related structures/functions of these enzymes.

Structure and Action Mechanism of Ligninolytic Enzymes

Decolorizing dye wastewater with Fenton's reagent

Use of Fenton reagent to improve organic chemical biodegradability.

Reactivities of a variety of alcohols, ethers, and amides toward hydroxyl radicals have been examined. Results are in encouraging agreement with radiation chemistry results. Reactivities of different C- H bonds have been dissected from the data and indicate that the hydroxyl radical is a strongly electrophilic species, so that electron supply is more important than C--H bond strength in determining reactivity. Comparison with gas-phase data shows similar reactivity patterns, but considerably faster reactions in H/sub 2/O. Radicals alpha to --OH, --OR, and amide N are readily oxidized by Fe/sup 3+/; tert-alkyl radicals are oxidized with more difficulty and allyl radicals hardly at all. In contrast, radicals RC (OH)CCl/sub 3/ are reduced by Fe/sup 2+/. Results are consistent with a fast oxidation of easily oxidized radicals by Fe/sup 3+/ via electron transfer, and a slower more general oxidation of radicals by Cu/sup 2+/ via a RCu(III) intermediate. (auth)

Fenton's reagent. IV. Structure and reactivity relations in the reactions of hydroxyl radicals and the redox reactions of radicals

L'oxydation des toluenes par le systeme cite dans le titre donne des acetates de benzyle et des benzaldehydes via la formation d'un radical cationique du type benzeniumyle

Oxidation of alkylbenzenes by S2O82−-CuII in acetic acid and acetonitrile

(C 3 F 7 COO) 2 et (C 7 F 15 COO) 2 reagissent rapidement avec le p-methoxytoluene et quelques p-dimethoxybenzenes dans CCl 2 FCClF 2 a 0°C. Avec le p-dimethoxybenzene la cinetique est du premier ordre par rapport a chaque composant. De hauts rendements en produits substitues sur le cycle sont obtenus sauf pour le dimethyl-2,5 dimethoxy-1,4 benzene qui donne le perfluoroacyl ester de benzyle substitue

Gamil M. El-Taliawi

Papers

Fenton's reagent. IV. Structure and reactivity relations in the reactions of hydroxyl radicals and the redox reactions of radicals

Oxidation of alkylbenzenes by S2O82−-CuII in acetic acid and acetonitrile

Electron-transfer reactions between perfluoroacyl peroxides and methoxybenzenes

Fenton's reagent. II. Reactions of carbonyl compounds and $alpha$,$beta$- unsaturated acids.

Oxidation of alkylbenzenes by peroxydisulfate-copper(II) in acetic acid and acetonitrile