Electrooxidation of cresols on carbon electrodes modified with phthalocyaninato and octabutoxyphthalocyaninato cobalt(II) complexes

Glassy carbon electrodes (GCE) modified with cobalt(II) phthalocyanine (CoP c-GCE) and cobalt(II) octabutoxyphthalocyanine (CoOBuPc-GCE) were employed for the electrochemical analysis of ortho-, meta-, and para-cresols. The ox idation potential of p-cresol was shifted towards less positive values to a larger extent, when compared to m- and o-cresols, on CoOBuPc-GCE. However, the GCE was less stable when modified with CoOBuPc than with CoPc. This is explained using the possible differences in the orientation of the adsorbe d phthalocyanine molecules on the electrode. Bulk electrolysis of p-cresol at anodic potentials (1.0 V versus AglAgCl) on carbon electrodes modified w ith CoPc resulted in the formation of radicals which coupled to form trimer ic products. On unmodified carbon electrodes, coupling of the radicals resu lted in dimeric products following bulk electrolysis. The products formed f ollowing bulk electrolysis were characterized by liquid chromatography coup led with mass spectrometry. (C) 2001 Elsevier Science B.V. All rights reser ved.