A series of 1,4-dichloroazoethanes (1-X/Y, X and Y = 4-NO2, 4-CN. 4-CH3 or 4-H) were studied in N,N-dimethylformamide using cyclic voltammetry. constant potential sweep voltammetry (CPSW) and constant potential electrolysis. The voltammograms of 1-X/Y exhibit an irreversible two-electron wave corresponding to dissociative electron transfer (DET) reduction of the carbon-chlorine bond resulting in formation of the azines 2-X/Y in quantitative yield. Additional redox waves correspond to the reversible reduction of the azines to the 2-X/Y center dot-radical anion and 2-X/Y2- dianion consecutively, with the exception of 1-NO2/NO2 where both NO2 groups are reduced simultaneously in a two-electron reversible wave. Thermodynamic and kinetic parameters were determined from CPSW: the standard reduction potentials (E degrees) vary between -0.7 and -1.3 V versus SCE as a function of electron-withdrawing substituent; the heterogeneous rate constants (k(het)) are consistent with a slow heterogeneous electron transfer with values ranging from 10(-3) to 10(-5) cm s(-1) : the transfer coefficients (alpha) for 1-NO2/NO2 and 1-NO2/H are greater than 0.5, indicative of a stepwise DET mechanism for the C-Cl bond cleavage while the remaining 1-X/Y compounds have alpha values between 0.35 and 0.5, and the intrinsic barriers are all significantly lower than predicted for a concerted DET. thereby also suggesting a stepwise DET mechanism. (C) 2010 Elsevier Ltd. All rights reserved.