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Electrochemically Driven C−H Hydrogen Abstraction Processes with the Tetrachloro‐Phthalimido‐N‐Oxyl (Cl 4 PINO) Catalyst
Author(s) -
Buckingham Mark A.,
Cunningham William,
Bull Steven D.,
Buchard Antoine,
Folli Andrea,
Murphy Damien M.,
Marken Frank
Publication year - 2018
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201800147
Subject(s) - chemistry , hydrogen atom abstraction , catalysis , reactivity (psychology) , redox , electron paramagnetic resonance , kinetic isotope effect , photochemistry , electrochemistry , reaction rate constant , radical , alcohol oxidation , aldehyde , ketone , hydrogen , inorganic chemistry , kinetics , organic chemistry , deuterium , electrode , medicine , physics , alternative medicine , pathology , nuclear magnetic resonance , quantum mechanics
The radical redox mediator tetrachloro‐phthalimido‐N‐oxyl (Cl 4 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 Cl 4 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 Cl 4 PINO sensitivity towards moisture. DFT methods are applied to confirm and predict C−H hydrogen abstraction reactivity.
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