A numerical modelling of voltammetric reduction of substituted iodobenzenes reaction series. A relationship between reductions in the consecutive-mode multistep system and a multicomponent system. Determination of the potential variation of the elementary charge transfer coefficient

Abstract

The cyclic voltammetry reduction process of the reaction series of substituted iodobenzenes X–C 6H 4–I where X=H, p-Cl, p-Br, p-I, p-CH 3, m-CF 3 was investigated in 0.3 M TBAP in DMF. A numerical model of the process consistent with the ECE mechanism of mono-iodobenzenes reduction and consecutive ECE–ECE reduction of p-diiodobenzene was applied. On the basis of α i vs. E p, i dependence, the value of ∂ α i /∂ E was found to be 0.37±0.07 for first electron transfer ( Eq. (10). The ECE–ECE system seems to be an another example of elementary α kinetic discrimination between two identical two-electron processes analogous to that described in a previous paper (Sanecki, P., Kaczmarski, K. (1999). J. Electroanal. Chem. 471, 14 and erratum to it (2001)). A method of simultaneous treatment of the substrate and all electroactive intermediates, i.e. the transformation of any experimental consecutive CV reduction curves (e.g. ECE or ECE–ECE) into curves corresponding to reduction of the multi-component systems is presented and discussed.