Electrocatalytic Oxidative Coupling of Methylquinolines on TEMPO-modified Graphite Felt Electrodes

Abstract 2- and 4-Methylquinolines were oxidized to 2,2′-dimethyl-4,4′-biquinolyl and 4,4′-dimethyl-2,2′-biquinolyl, respectively, both in ca. 94% isolated yield and ca. 90% current efficiency on a graphite felt electrode coated with a thin poly(acrylic acid) layer containing 4-amino-2,2,6,6-tetramethylpiperidinyl-1-oxyl (4-amino-TEMPO). The reaction proceeds via electrocatalytic oxidation of the modified-TEMPO species. The electrode was not inactivated during electrolysis and could be used repeatedly.