J. Electroanal. Chem., 191 (1985) 303-310 303 Elsevier Sequoia S.A., Lausanne - Printed in The Netherlands DIFFERENTIAL PULSE POLAROGRAPHY FOR A DIMERIZATION PROCESS M. DE JUAN, A.M. HER,AS, L. CAMACHO * and J.L. AVILA Department of Physical Chemistry, Faculty of Sciences, University of Cbrdoba, Cbrdoba (Spain) C. JIMI~NEZ Department of Organic Chemistry, Faculty of Sciences, University of Cbrdoba, Cbrdoba (Spain) (Received 3rd January 1985; in revised form 19th March 1985) ABSTRACT The i-t-E relations have been analyzed in differential pulse polarography (DPP) for processes in which a very fast dimerization preceded by a reversible electron transfer takes place. The peak half-width and the variations of parameters such as Ep with t and the reactant concentration have been studied. These parameters can be related to those obtained by dc polarography for the same process. The results obtained have been experimentally verified in the dimerization process of l-(p-methoxy-phenyl)-hepten- 1-one-3 (MHO) in methanol. INTRODUCTION Dimerization reactions following a reversible electron transfer are very common and their mechanisms have been widely studied by DC polarography [1-5]. Gener- ally, radical-radical dimerization reactions have large rate constants, in many cases over 104 M -1 s -1 (see, for example, refs. 6-9), which allows the use of the reaction layer assumption to solve the corresponding reactions system. The aim of this work is to apply such an approximation to the determination of the i-t-E relation for a dimerization process in DPP. The limits for the use of this approximation should be narrower than in DC polarography, owing to the short duration of the pulses applied. However, the usually large rate constants of these processes may result in a wider range of applicability. There are numerous studies in the literature [10-22] dealing with processes either with or without kinetic first-order complications by DPP. The advantages of this technique, such as sensibility, rapidity, elimination of charge effects, etc., have led us * All correspondence should be addressed to: Dr. L. Camacho, Departamento de Quimica Fisica, Facultad de Ciencias, 14004 Ctrdoba, Spain. 0022-0728/85/$03.30 © 1985 Elsevier Sequoia S.A.