Electrochemically controlled chemically reversible transformation of α-tocopherol (vitamin E) into its phenoxonium cation

Leodrina L. Williams; Richard D. Webster

doi:10.1021/ja046648j

Electrochemically controlled chemically reversible transformation of α-tocopherol (vitamin E) into its phenoxonium cation

Leodrina L. Williams, Richard D. Webster^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

107 Citations (Scopus)

Abstract

alpha;-Tocopherol (α-TOH) can be electrochemically oxidized in CH₃CN containing BU₄NPF₆ in a chemically reversible two-electron/one-proton (ECE) process to form the phenoxonium cation (α-TO⁺) that is stable for at least several hours at 243 K. In the presence of up to ∼1% CF₃SO₃H, α-TO ⁺ exists in equilibrium with the α-tocopherol cation radical (α-TOH^+.), whereas at concentrations between ∼1-3% CF ₃SO₃H the electrochemical oxidation of α-TOH occurs by close to one-electron to form α-TOH^+.. α-TOH ^+. can be further oxidized in a one-electron process to form the α-tocopherol dication (α-TOH²⁺). The identity and stability of the phenolic cationic compounds were determined by a combination of electrochemical (cyclic voltammetry and controlled potential electrolysis) and in situ spectroscopic (UV-vis-NIR, FTIR, EPR, and NMR) analysis.

Original language	English
Pages (from-to)	12441-12450
Number of pages	10
Journal	Journal of the American Chemical Society
Volume	126
Issue number	39
DOIs	https://doi.org/10.1021/ja046648j
Publication status	Published - 6 Oct 2004

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@article{16f663969870473fb7dd72c1cf614295,

title = "Electrochemically controlled chemically reversible transformation of α-tocopherol (vitamin E) into its phenoxonium cation",

abstract = "alpha;-Tocopherol (α-TOH) can be electrochemically oxidized in CH3CN containing BU4NPF6 in a chemically reversible two-electron/one-proton (ECE) process to form the phenoxonium cation (α-TO+) that is stable for at least several hours at 243 K. In the presence of up to ∼1% CF3SO3H, α-TO + exists in equilibrium with the α-tocopherol cation radical (α-TOH+.), whereas at concentrations between ∼1-3% CF 3SO3H the electrochemical oxidation of α-TOH occurs by close to one-electron to form α-TOH+.. α-TOH +. can be further oxidized in a one-electron process to form the α-tocopherol dication (α-TOH2+). The identity and stability of the phenolic cationic compounds were determined by a combination of electrochemical (cyclic voltammetry and controlled potential electrolysis) and in situ spectroscopic (UV-vis-NIR, FTIR, EPR, and NMR) analysis.",

author = "Williams, {Leodrina L.} and Webster, {Richard D.}",

year = "2004",

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doi = "10.1021/ja046648j",

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volume = "126",

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journal = "Journal of the American Chemical Society",

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T1 - Electrochemically controlled chemically reversible transformation of α-tocopherol (vitamin E) into its phenoxonium cation

AU - Williams, Leodrina L.

AU - Webster, Richard D.

PY - 2004/10/6

Y1 - 2004/10/6

N2 - alpha;-Tocopherol (α-TOH) can be electrochemically oxidized in CH3CN containing BU4NPF6 in a chemically reversible two-electron/one-proton (ECE) process to form the phenoxonium cation (α-TO+) that is stable for at least several hours at 243 K. In the presence of up to ∼1% CF3SO3H, α-TO + exists in equilibrium with the α-tocopherol cation radical (α-TOH+.), whereas at concentrations between ∼1-3% CF 3SO3H the electrochemical oxidation of α-TOH occurs by close to one-electron to form α-TOH+.. α-TOH +. can be further oxidized in a one-electron process to form the α-tocopherol dication (α-TOH2+). The identity and stability of the phenolic cationic compounds were determined by a combination of electrochemical (cyclic voltammetry and controlled potential electrolysis) and in situ spectroscopic (UV-vis-NIR, FTIR, EPR, and NMR) analysis.

AB - alpha;-Tocopherol (α-TOH) can be electrochemically oxidized in CH3CN containing BU4NPF6 in a chemically reversible two-electron/one-proton (ECE) process to form the phenoxonium cation (α-TO+) that is stable for at least several hours at 243 K. In the presence of up to ∼1% CF3SO3H, α-TO + exists in equilibrium with the α-tocopherol cation radical (α-TOH+.), whereas at concentrations between ∼1-3% CF 3SO3H the electrochemical oxidation of α-TOH occurs by close to one-electron to form α-TOH+.. α-TOH +. can be further oxidized in a one-electron process to form the α-tocopherol dication (α-TOH2+). The identity and stability of the phenolic cationic compounds were determined by a combination of electrochemical (cyclic voltammetry and controlled potential electrolysis) and in situ spectroscopic (UV-vis-NIR, FTIR, EPR, and NMR) analysis.

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U2 - 10.1021/ja046648j

DO - 10.1021/ja046648j

M3 - Article

SN - 0002-7863

VL - 126

SP - 12441

EP - 12450

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 39

ER -

Electrochemically controlled chemically reversible transformation of α-tocopherol (vitamin E) into its phenoxonium cation

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