Electrochemically Driven C−H Hydrogen Abstraction Processes with the Tetrachloro‐Phthalimido‐N‐Oxyl (Cl4PINO) Catalyst. Issue 8 (6th April 2018)

• Record Type: Journal Article
• Authors: Buckingham, Mark A.; Cunningham, William; Bull, Steven D.; Buchard, Antoine; Folli, Andrea; Murphy, Damien M.; Marken, Frank
• Is Part Of: Electroanalysis. Volume 30:Issue 8(2018)
• Page Start: 1698
• Page End: 1705
• Publication Date: 2018-04-06
• Subjects: C−H abstraction -- voltammetry -- redox mediator -- TEMPO -- radicalisation -- fuel.; Electrochemical analysis -- Periodicals; Chemistry, Analytical -- Periodicals; Electrochemistry -- Periodicals; 543.4
• DOI: 10.1002/elan.201800147
• Languages: English
• ISSNs: 1040-0397

Abstract

Abstract: The radical redox mediator tetrachloro‐phthalimido‐N‐oxyl (Cl4 PINO) 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 k 1, confirmed by kinetic isotope effect) and a fast radical‐radical coupling of the resulting alcohol radical with Cl4 PINO to give a ketal that only slowly releases the aldehyde/ketone and redox mediator precursor back into solution (rate constant k 2 ). In situ electrochemical EPR reveals Cl4 PINO sensitivity towards moisture. DFT methods are applied to confirm and predict C−H hydrogen abstraction reactivity. Abstract :