Abstract

We report on the synthesis of cobalt 2,3,9,10,16,17,23,24-octakis(2-ethylhexyloxy)phthalocyanine. This complex, when pre-adsorbed onto graphite electrodes, is active for the electro-oxidation of 2-mercaptoethanol. Its activity is higher than that of cobalt phthalocyanine and cobalt tetrasulfonated phthalocyanine adsorbed on graphite. The voltammetric response of adsorbed cobalt 3,4-octaethylhexyl-oxyphthalocyanine exhibits both Co(II)/Co(I) and Co(III)/Co(II) reversible processes. However, the Co(III)/ Co(II) couple shows a pH dependence that is different from that reported for other cobalt phthalocyanine derivatives. The much higher activity of cobalt 3,4-octaethylhexyloxyphthalocyanine compared with cobalt tetrasulfonated phthalocyanine and cobalt phthalocyanine is attributed to the electron-donating ability of the ethylhexyloxy substituents on the periphery of the phthalocyanine ligand. Copyright © 1999 John Wiley & Sons, Ltd.