The Oxidation of Hydroquinone by Protonated Quinone.

Hammerich, Ole; Parker, Vernon D.; Silva, N. De; Norin, Torbjörn; Wijekoon, Donald; Ulff, Bengt

doi:10.3891/acta.chem.scand.36b-0063

Cited by 17 publications

(12 citation statements)

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“…However, considering that the half peak width is close to 37 mV (this value is lower than 57 mV for a reversible one-electron process and higher than 28.5 mV for a single two-electron reversible wave) [29], it can be proposed that the reversible wave is two-electron in nature and it involves proton transfers in equilibrium. These results at room temperature are consistent with those reported by Hammerich et al for the oxidation of QH 2 in CH 2 Cl 2 at very low temperatures [30], which allow them to conclude that a reversible two-electron process is possible depending on the medium acidity. They also noted a final reversible one-electron transfer process at higher acidity levels which supports that the passage from two-electron to one-electron reversible process is due to the stability of the species involved before and after the QH 2 oxidation under experimental conditions.…”

Section: Electrochemical Behaviour Of Hydroquinone In Acetonitrilesupporting

confidence: 93%

The role of acids and bases on the electrochemical oxidation of hydroquinone: Hydrogen bonding interactions in acetonitrile

Astudillo

Tiburcio

González

2007

Journal of Electroanalytical Chemistry

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Section: Electrochemical Behaviour Of Hydroquinone In Acetonitrilesupporting

confidence: 93%

The role of acids and bases on the electrochemical oxidation of hydroquinone: Hydrogen bonding interactions in acetonitrile

Astudillo

Tiburcio

González

2007

Journal of Electroanalytical Chemistry

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“…The CV is irreversible due to a slow electron transfer (ET) at the electrode. The redox behaviour of quinones have previously been studied and the reversibility has been found to be highly medium‐dependent 25, 26. In particular, the proton concentration is known to influence the redox behaviour 25.…”

Section: Resultsmentioning

confidence: 99%

“…The redox behaviour of quinones have previously been studied and the reversibility has been found to be highly medium‐dependent 25, 26. In particular, the proton concentration is known to influence the redox behaviour 25. This is perhaps not surprising since the overall redox process involves a two‐electron oxidation combined with a single or double deprotonation.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Aspects of On‐Line Electrochemical Tagging of Free L‐Cysteine Residues during Electrospray Ionisation for Mass Spectrometry in Protein Analysis

et al. 2003

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The mechanistic details behind an electrochemically induced tagging of L-cysteine residues in peptides and proteins have been unravelled using cyclic voltammetry. It was found that when hydroquinone is oxidised in the medium used in electrospray ionisation mass spectrometry (ESI-MS) a protonated form of benzoquinone is produced that acts as an efficient electrophile for free L-cysteine residues. Upon substitution of L-cysteine the reduced form of the adduct is formed, which may be further oxidised leading to further substitution of L-cysteine. Digital simulations of the cyclic voltammograms corroborated the mechanism and allowed a determination of the homogeneous second order rate constant corresponding to the addition of L-cysteine onto the protonated form of benzoquinone. The selectivity of the tagging process was confirmed using ESI-MS, which showed that a protein without L-cysteine residues does not react with benzoquinone dissolved in the medium. Finally, the kinetic information obtained in this investigation is used to discuss the optimal parameters for a nanospray capable of quantitative tagging of L-cysteine residues.

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“…Cyclic voltammetry has itself proved informative on the physical properties of such a couple [8]. In particular, Hammerich and Parker [18] studied the oxidation of hydroquinone in dichloromethane. In the presence of strong proton donors and at --50 C, the oxidation was a quasi-reversible one-electron process involving the couple QH2/QH~ ÷.…”

Section: The Possible Chemical Mechanisms Of P-benzoquinol Oxidationmentioning

confidence: 99%

Mechanisms of quinol oxidation in photosynthesis

Rich

1985

Photosynth Res

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The mechanisms by which para-benzoquinols can be oxidized is reviewed. Emphasis is placed on the information available from chemical and electrochemical studies which may provide insight into the biochemical mechanisms of plastoquinol oxidation in the chloroplast. Three mechanisms of quinol oxidation are possible: (1) The removal of an electron from the quinol, QH inf2 (sup·t) , directly to produce the radical cation, QH 2 (·+) . This may be achieved electrochemically only at very high potential in acidic media. The reaction may be of relevance to D1, the donor to P-680. (2) The removal of an electron from the anionic quinol. QH(-), formed by quinol deprotonation. It is likely that the catalytic mechanism of the cytochrome bf complex involves this mechanism. (3) The removal of an electron from the dianionic quinol, Q(2-). This route will be dominant only under basic or aprotic conditions and at very low potentials.

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The Oxidation of Hydroquinone by Protonated Quinone.

Cited by 17 publications

References 0 publications

The role of acids and bases on the electrochemical oxidation of hydroquinone: Hydrogen bonding interactions in acetonitrile

The role of acids and bases on the electrochemical oxidation of hydroquinone: Hydrogen bonding interactions in acetonitrile

Mechanistic Aspects of On‐Line Electrochemical Tagging of Free L‐Cysteine Residues during Electrospray Ionisation for Mass Spectrometry in Protein Analysis

Mechanisms of quinol oxidation in photosynthesis

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