The mechanisms of oxidation of a series of a-alkyl substituted mono and dimethoxylated benzyl alcohols catalysed by mesotetrakis(4-N-methylpyridynium)porphyrin iron (III) chloride (FeTMPyPCl) and meso-tetrakis(4-sulfonatophenyl)porphyrin iron (III) chloride (FeTSPPCl) in aqueous solution with KHSO5 as oxygen atom donor and by meso-tetrakis(pentafluorophenyl)-porphyrin iron (III) chloride (FeTPFPPCl) in dichloromethane employing iodosylbenzene as oxidant have been investigated. In the highly polar aqueous medium an electron transfer mechanism is operating. With FeTMPyPCl, which is a much more efficient catalyst than FeTSPPCl due to the presence of stronger electron withdrawing substituents, formation of side-chain oxidation products accompanies generation of nuclear oxidation products. In the low polar solvent dichloromethane, two competing mechanism have been suggested: hydrogen atom transfer and formation of a complex between the active species iron-oxo porphyrin radical cation and the substrate.
Iron porphyrins-catalysed oxidation of alpha-alkyl substituted mono and dimethoxylated benzyl alcohols / Fabbri, Claudia; Aurisicchio, C; Lanzalunga, Osvaldo. - In: CENTRAL EUROPEAN JOURNAL OF CHEMISTRY. - ISSN 1895-1066. - STAMPA. - 6 (2):(2008), pp. 145-153. [10.2478/s11532-008-0005-8]
Iron porphyrins-catalysed oxidation of alpha-alkyl substituted mono and dimethoxylated benzyl alcohols
FABBRI, Claudia;LANZALUNGA, Osvaldo
2008
Abstract
The mechanisms of oxidation of a series of a-alkyl substituted mono and dimethoxylated benzyl alcohols catalysed by mesotetrakis(4-N-methylpyridynium)porphyrin iron (III) chloride (FeTMPyPCl) and meso-tetrakis(4-sulfonatophenyl)porphyrin iron (III) chloride (FeTSPPCl) in aqueous solution with KHSO5 as oxygen atom donor and by meso-tetrakis(pentafluorophenyl)-porphyrin iron (III) chloride (FeTPFPPCl) in dichloromethane employing iodosylbenzene as oxidant have been investigated. In the highly polar aqueous medium an electron transfer mechanism is operating. With FeTMPyPCl, which is a much more efficient catalyst than FeTSPPCl due to the presence of stronger electron withdrawing substituents, formation of side-chain oxidation products accompanies generation of nuclear oxidation products. In the low polar solvent dichloromethane, two competing mechanism have been suggested: hydrogen atom transfer and formation of a complex between the active species iron-oxo porphyrin radical cation and the substrate.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.