Electrocatalytic Oxidative Coupling Reaction of Naphthols and Naphthol Ethers on a TEMPO Modified Graphite Felt Electrode

Abstract 2-Naphthol and 2-methoxynaphthalene were quantitatively oxidized to the corresponding 1,1′-binaphthyls in more than 90% current efficiency on a graphite felt electrode coated with a thin poly(acrylic acid) layer immobilizing 4-amino-2,2,6,6-tetramethylpiperidinyl-1-oxyl (4-amino-TEMPO). 1-Naphthol and 1-methoxynaphthalene were also completely converted to the predicted 1,1′-, 1,2′-, and 2,2′- positioned coupling products. The reaction proceeds via electrocatalytic oxidation of the modified-TEMPO species. The electrode was not inactivated during electrolysis and could be used repeatedly.