Participation of multioxidants in the pH dependence of the reactivity of ferrate(VI)

Takashi Kamachi, Tomohisa Kouno, Kazunari Yoshizawa

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Alcohol oxidation by ferrate (FeO42-) in water is investigated from B3LYP density functional theory calculations in the framework of polarizable continuum model. The oxidizing power of three species, nonprotonated, monoprotonated, and diprotonated ferrates, was evaluated. The LUMO energy levels of nonprotonated and monoprotonated ferrates are greatly reduced by solvent effects, and as a result the oxidizing power of these two species is increased enough to effectively mediate a hydrogen-atom abstraction from the C-H and O-H bonds of methanol. The oxidizing power of these oxidants increases in the order nonprotonated ferrate < monoprotonated ferrate < diprotonated ferrate. The reaction pathway is initiated by C-H bond activation, followed by the formation of a hydroxymethyl radical intermediate or an organometallic intermediate with an Fe-C bond. Kinetic aspects of this reaction are analyzed from calculated energy profiles and experimentally known pK a values. The pH dependence of this reaction in water is explained well in terms of a multioxidant scheme.

Original languageEnglish
Pages (from-to)4380-4388
Number of pages9
JournalJournal of Organic Chemistry
Volume70
Issue number11
DOIs
Publication statusPublished - May 27 2005

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Water
Organometallics
Oxidants
Electron energy levels
Density functional theory
Methanol
ferrate ion
Hydrogen
Chemical activation
Alcohols
Atoms
Oxidation
Kinetics

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

Cite this

Participation of multioxidants in the pH dependence of the reactivity of ferrate(VI). / Kamachi, Takashi; Kouno, Tomohisa; Yoshizawa, Kazunari.

In: Journal of Organic Chemistry, Vol. 70, No. 11, 27.05.2005, p. 4380-4388.

Research output: Contribution to journalArticle

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N2 - Alcohol oxidation by ferrate (FeO42-) in water is investigated from B3LYP density functional theory calculations in the framework of polarizable continuum model. The oxidizing power of three species, nonprotonated, monoprotonated, and diprotonated ferrates, was evaluated. The LUMO energy levels of nonprotonated and monoprotonated ferrates are greatly reduced by solvent effects, and as a result the oxidizing power of these two species is increased enough to effectively mediate a hydrogen-atom abstraction from the C-H and O-H bonds of methanol. The oxidizing power of these oxidants increases in the order nonprotonated ferrate < monoprotonated ferrate < diprotonated ferrate. The reaction pathway is initiated by C-H bond activation, followed by the formation of a hydroxymethyl radical intermediate or an organometallic intermediate with an Fe-C bond. Kinetic aspects of this reaction are analyzed from calculated energy profiles and experimentally known pK a values. The pH dependence of this reaction in water is explained well in terms of a multioxidant scheme.

AB - Alcohol oxidation by ferrate (FeO42-) in water is investigated from B3LYP density functional theory calculations in the framework of polarizable continuum model. The oxidizing power of three species, nonprotonated, monoprotonated, and diprotonated ferrates, was evaluated. The LUMO energy levels of nonprotonated and monoprotonated ferrates are greatly reduced by solvent effects, and as a result the oxidizing power of these two species is increased enough to effectively mediate a hydrogen-atom abstraction from the C-H and O-H bonds of methanol. The oxidizing power of these oxidants increases in the order nonprotonated ferrate < monoprotonated ferrate < diprotonated ferrate. The reaction pathway is initiated by C-H bond activation, followed by the formation of a hydroxymethyl radical intermediate or an organometallic intermediate with an Fe-C bond. Kinetic aspects of this reaction are analyzed from calculated energy profiles and experimentally known pK a values. The pH dependence of this reaction in water is explained well in terms of a multioxidant scheme.

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