Application of 13C nmr spectroscopy to the elucidation of the electrochemical oxidation mechanism of the l-ascorbic and d-araboascorbic acids

Acerete, C.; Garrigos, Lluis; Guilleme, J.; Dı́ez, Ernesto; Aldaz, A.

doi:10.1016/0013-4686(81)85074-8

Cited by 20 publications

(5 citation statements)

References 8 publications

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“…At unactivated carbon electrodes the oxidation of ascorbate to the free radical is rate limiting. At heat-treated glassy carbon the rate-limiting step for the oxidation shifts to the second-electron transfer in accord with the behavior observed at metal electrodes (55)(56)(57)(58). At higher values of overpotential, the rate-limiting step for oxidation of ascorbate reverts to a fist-electron rate-limiting step.…”

Section: Discussionsupporting

confidence: 78%

Heterogeneous mechanisms of the oxidation of catechols and ascorbic acid at carbon electrodes

et al. 1986

Anal. Chem.

213

149

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Section: Discussionsupporting

confidence: 78%

Heterogeneous mechanisms of the oxidation of catechols and ascorbic acid at carbon electrodes

et al. 1986

Anal. Chem.

213

149

View full text Add to dashboard Cite

“…Oxidation of ascorbate at carbon electrodes.--The oxidation mechanisms of ascorbic acid and its optical isomer, d-araboascorbic acid, have been studied extensively at gold and mercury electrodes (22)(23)(24)(25). At pH 7.4 the oxidation involves the loss of two electrons and one proton.…”

Section: Resultsmentioning

confidence: 99%

Methods to Improve Electrochemical Reversibility at Carbon Electrodes

Wightman

Deakin

Kovach

et al. 1984

J. Electrochem. Soc.

180

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Carbon electrodes are frequently used for electroanalytical studies of oxidizable compounds. However, for many compounds, heterogeneous charge‐transfer rates are very slow at carbon electrodes, leading to ill‐defined voltammograms. Ascorbic acid (vitamin C) is perhaps one of the best examples of such phenomena, with a peak potential that is approximately 350 mV more positive at most carbon surfaces than at mercury electrodes. Ferricyanide also exhibits voltammetry at carbon electrodes that is less reversible than at noble metal electrodes. Various electrode surface treatments have been employed to accelerate the rates of ascorbate and ferricyanide electrolysis. Pretreatment of carbon fiber electrodes with a high current density results in a significant shift of the voltammetric waves for both compounds to potentials where they are more easily electrolyzed. Similar results are obtained with glassy carbon surfaces that have been heated at 500°C under reduced pressure. An alternate method to increase reversibility is the judicious use of polishing procedures. Thus, it appears that the surface properties of carbon electrodes can have profound effects on the observed voltammetry.

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“…During the last three decades much effort has been made to elucidate the mechanism and the kinetics of the electrochemical oxidation of L-ascorbic acid [1][2][3][4][5][6][7][8][9][10][11][12][13] on different metallic electrodes. It has been established 10 that its first oxidation wave corresponds to the transfer of two electrons and two protons, forming dehydro-L-ascorbic acid, followed by the fast hydration of the latter species.…”

Section: Introductionmentioning

confidence: 99%

“…The most complete kinetic studies of the oxidation of L-ascorbic acid were performed by Aldaz et al, [4][5][6][7][8][9] who demonstrated 4 the existence of a radical anion as an intermediate species in the two-electron oxidation of L-ascorbic acid at Pt, Ga, Au, and Hg electrodes, using the electron paramagnetic resonance (EPR) technique. This observation clearly indicated that the electron transfers proceeded in two separate steps.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Determination Using Arrays of Variable-Sized Channel Microband Electrodes: The Oxidation of Ascorbic Acid in Aqueous Solution

1998

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“Two-dimensional voltammetry” using arrays of variable-sized gold channel microband electrodes in combination with variable flow rate measurements together with independent gold rotating disk electrode (RDE) data is applied to characterize the oxidation mechanism of l-ascorbic acid (AH2) to dehydro-l-ascorbic acid in aqueous solutions. At pH 2.1 and very low mass transport conditions the reaction is consistent with a CECE mechanism, while at higher mass transport conditions an ECfastCE mechanism is followed. At pH 6.7, the results are again consistent with an ECE mechanism. The following mechanism is proposed: AH2 ⇌ AH- + H+ (k CEE), AH- → AH• + e, AH• → A• - + H+ (k ECE), A• - → A + e (CECE); AH2 ⇌ AH2 + + e, AH2 + → AH• + H+(fast), AH• → A• - + H+ (k ECE), A• - → A + e (ECfastCE); where, only the first pathway applies at pH 6.7, AH- being the starting species. Values of 3.4 × 103 s-1 and 500 s-1 are found for the rate constants k CEE and k ECE, respectively.

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Application of 13C nmr spectroscopy to the elucidation of the electrochemical oxidation mechanism of the l-ascorbic and d-araboascorbic acids

Cited by 20 publications

References 8 publications

Heterogeneous mechanisms of the oxidation of catechols and ascorbic acid at carbon electrodes

Heterogeneous mechanisms of the oxidation of catechols and ascorbic acid at carbon electrodes

Methods to Improve Electrochemical Reversibility at Carbon Electrodes

Mechanistic Determination Using Arrays of Variable-Sized Channel Microband Electrodes: The Oxidation of Ascorbic Acid in Aqueous Solution

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