PNAS 1997-04-29

Microperoxidase/H2O2-mediated alkoxylating dehalogenation of halophenol derivatives in alcoholic media.

A M Osman, S Boeren, M G Boersma, C Veeger, I M Rietjens

Index: Proc. Natl. Acad. Sci. U. S. A. 94(9) , 4295-9, (1997)

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Abstract

The results of this study report the H2O2-driven microperoxidase-8 (MP8)-catalyzed dehalogenation of halophenols such as 4-fluorophenol, 4-chlorophenol, 4-bromophenol, and 2-fluorophenol in alcoholic solvents. In methanol, the conversion of the para-halophenols and 2-fluorophenol to, respectively, 4-methoxyphenol and 2-methoxyphenol, as the major dehalogenated products is observed. In ethanol, 4-ethoxyphenol is the principal dehalogenated product formed from 4-fluorophenol. Two mechanisms are suggested for this MP8-dependent alkoxylating dehalogenation reaction. In one of these mechanisms the oxene resonant form of compound I of MP8 is suggested to react with methanol forming a cofactor-peroxide-alkyl intermediate. This intermediate reacts with the reactive pi-electrons of the substrate, leading to the formation of the alkoxyphenols and the release of the fluorine substituent as fluoride anion.