Electrochemically Driven C-H Hydrogen Abstraction Processes with the Tetrachloro-Phthalimido-N-Oxyl (Cl4PINO) Catalyst

Frank Marken; Mark A. Buckingham; Steven Bull; William Cunningham; Antoine Buchard; Andrea Folli; Damien Murphy

doi:10.1002/elan.201800147

Electrochemically Driven C-H Hydrogen Abstraction Processes with the Tetrachloro-Phthalimido-N-Oxyl (Cl₄PINO) Catalyst

Frank Marken, Mark A. Buckingham, Steven Bull, William Cunningham, Antoine Buchard, Andrea Folli, Damien Murphy

Cardiff University

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

5 Citations (SciVal)

111 Downloads (Pure)

Abstract

The radical redox mediator tetrachloro-phthalimido-N-oxyl (Cl₄PINO) is generated at a glassy carbon electrode and investigated for the model oxidation of primary and secondary alcohols with particular attention to reaction rates and mechanism. The two-electron oxidation reactions of a range of primary, secondary, and cyclic alcohols are dissected into an initial step based on C-H hydrogen abstraction (rate constant k1, confirmed by kinetic isotope effect) and a fast radical-radical coupling of the resulting alcohol radical with Cl₄PINO to give a ketal that only slowly releases the aldehyde/ketone and redox mediator precursor back into solution (rate constant k2). In situ electrochemical EPR reveals Cl₄PINO sensitivity towards moisture. DFT methods are applied to confirm and predict C-H hydrogen abstraction reactivity.

Original language	English
Pages (from-to)	1706-1713
Number of pages	8
Journal	Electroanalysis
Volume	30
Issue number	8
Early online date	6 Apr 2018
DOIs	https://doi.org/10.1002/elan.201800147
Publication status	Published - 1 Aug 2018

Keywords

C−H abstraction
TEMPO
fuel.
radicalisation
redox mediator
voltammetry

ASJC Scopus subject areas

Analytical Chemistry
Electrochemistry

Access to Document

10.1002/elan.201800147

Electroanalysis_PINO_1a_revision_nh (PDF)
This is the peer reviewed version of the following article: M. A. Buckingham, W. Cunningham, S. D. Bull, A. Buchard, A. Folli, D. M. Murphy, F. Marken, Electroanalysis 2018, 30, 1706-1713, which has been published in final form at https://doi.org/10.1002/elan.201800147. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Accepted author manuscript, 1.31 MB

Cite this

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abstract = "The radical redox mediator tetrachloro-phthalimido-N-oxyl (Cl4PINO) is generated at a glassy carbon electrode and investigated for the model oxidation of primary and secondary alcohols with particular attention to reaction rates and mechanism. The two-electron oxidation reactions of a range of primary, secondary, and cyclic alcohols are dissected into an initial step based on C-H hydrogen abstraction (rate constant k1, confirmed by kinetic isotope effect) and a fast radical-radical coupling of the resulting alcohol radical with Cl4PINO to give a ketal that only slowly releases the aldehyde/ketone and redox mediator precursor back into solution (rate constant k2). In situ electrochemical EPR reveals Cl4PINO sensitivity towards moisture. DFT methods are applied to confirm and predict C-H hydrogen abstraction reactivity.",

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AU - Marken, Frank

AU - Buckingham, Mark A.

AU - Bull, Steven

AU - Cunningham, William

AU - Buchard, Antoine

AU - Folli, Andrea

AU - Murphy, Damien

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AB - The radical redox mediator tetrachloro-phthalimido-N-oxyl (Cl4PINO) is generated at a glassy carbon electrode and investigated for the model oxidation of primary and secondary alcohols with particular attention to reaction rates and mechanism. The two-electron oxidation reactions of a range of primary, secondary, and cyclic alcohols are dissected into an initial step based on C-H hydrogen abstraction (rate constant k1, confirmed by kinetic isotope effect) and a fast radical-radical coupling of the resulting alcohol radical with Cl4PINO to give a ketal that only slowly releases the aldehyde/ketone and redox mediator precursor back into solution (rate constant k2). In situ electrochemical EPR reveals Cl4PINO sensitivity towards moisture. DFT methods are applied to confirm and predict C-H hydrogen abstraction reactivity.

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