Catalytic activity of halogenated iron porphyrins in alkene and alkane oxidations by iodosylbenzene and hydrogen peroxide

Journal of the Brazilian Chemical Society

André Aparecido Guedes²  John R. L. Smith¹  Otaciro R. Nascimento¹  Débora F. Costa Guedes²  Marilda Das Dores Assis² 

[1] ,Universidade de São Paulo Faculdade de Filosofia Ciências e Letras de Ribeirão Preto Departamento de QuímicaRibeirão Preto SP ,Brazil

关键词: poly-halogenated iron porphyrins;    catalysis;    supported catalysts;    hydrocarbon oxidation;   

DOI  :  10.1590/S0103-50532005000500024

来源: SciELO

【 摘 要 】

A poly-halogenated iron porphyrin, Fe(PCl8)Cl, has been synthesised and used as a catalyst in hydrocarbon oxidations by iodosylbenzene and hydrogen peroxide both in solution and covalently bound to aminopropylated silica. The poly-chlorinated iron porphyrin shows the same efficiency of the related Fe(P)Cl, in the epoxidation of alkenes but higher efficiency in the hydroxylation of alkanes by iodosylbenzene, with increased preference for the oxidation of secondary carbon in adamantane and primary carbon in the oxidation of pentane. These selectivities may reflect the steric constraints around the oxo-iron species or, alternatively, it may arise from the greater reactivity of the active oxidant from Fe(PCl8)Cl. The supported iron(III) porphyrin showed lower activity as compared with the homogeneous analogue and the related supported Fe(P)Cl. The poly-chlorinated iron porpyrin is a poor catalyst with hydrogen peroxide. Excessive substitutuion by electron withdrawing groups on the porphyrin periphery eventually prohibits the formation of the key intermediate in catalytic oxidations. The alternative oxidation mechanism could involve radical participation.

【 授权许可】

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