Voltammetric Reductions of Ring-Substituted Acetophenones. 2. A Senior-Level Experiment Requiring Classification of an Electrochemical Mechanism as Stepwise or Concerted

An experiment suitable for upper-level undergraduates in which they determine the characteristics of a chemically coupled electron transfer (EC) mechanism is described. Students examine the free-energy barrier between an unstable radical anion and the products of its decomposition for ring-substituted and alpha-substituted acetophenones, acetanilides, and alkyl halides. Digital simulation is used to estimate the value of the standard potential, E°. Calculation of the electrochemical transfer coefficient, α, allows a determination of whether the electron transfer occurs in a single step (concerted) or follows the generation of the intermediate radical anion (stepwise).