A green route to conducting polyaniline by copper catalysis

The oxidative polymerization of N-(4-aminophenyl)aniline (AD) to the conducting emeraldine salt (2.6 x 10(-2) S cm(-1)) has been investigated using dioxygen or hydrogen peroxide as the oxidant in aqueous solution under mild conditions. The spontaneous oxidation by O(2) takes place with a modest yield (13%) while H(2)O(2) allows a better result (43% yield). On adding acetonitrile as a co-solvent, the polymerization is completely suppressed with both the reagents. A strong catalytic effect has been detected by using Cu, CuCl, and CuCl(2), being all these simple copper compounds similarly efficient using either O(2) or H(2)O(2) reagents, thus allowing yields up to 86-93% of emeraldine. The poisoning effect of acetonitrile has been observed also in the case of the copper-catalyzed reactions but with a minor impact (5-14% decrement). (C) 2009 Elsevier Inc. All rights reserved.