Publication – TEMPO-mediated electrooxidation of primary and secondary alcohols in a microfluidic electrolytic cell
ChemSusChem Special Issue: Flow ChemistryVolume 5, Issue 2, pages 326–331, February 13, 2012
Joseph Hill-Cousins1, Jekaterina Kuleshova1, Robert Green1, Peter Birkin1, Derek Pletcher1, Toby Underwood2, Stuart Leach3 and Richard Brown1
1 – School of Chemistry, University of Southampton, Southampton, Hampshire, SO17 1BJ
2 – Pfizer Ltd, Sandwich, Kent, CT13 9NJ
3 – GlaxoSmithKline, Stevenage, Herts, SG1 2NY
This paper describes a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) catalysed electro-oxidation of a range of 15 primary and secondary alcohols to the corresponding aldehyde or ketone at ambient temperatures. This no-electrolyte process was fully optimised and gave outstanding selectivity across the range of alcohols studied, also the TEMPO catalyst was electrochemically regenerated and reused a number of times giving an environmentally acceptable process.
Abstract: A general procedure for the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated electrooxidation of primary and secondary alcohols modified for application in a microfluidic electrolytic cell is described. The electrocatalytic system utilises a buffered aqueous tert-butanol reaction medium, which operates effectively without the requirement for additional electrolyte, providing a mild protocol for the oxidation of alcohols to aldehydes and ketones at ambient temperature on a laboratory scale. Optimisation of the process is discussed along with the oxidation of 15 representative alcohols.