Voltammetric Reductions of Ring-Substituted Acetophenones. 1. Determination of an Electron-Transfer Mechanism Using Cyclic Voltammetry and Computer Modeling: The Formation and Fate of a Radical Anion

Abstract

In a sophomore/junior-level experiment suitable for intermediate organic or instrumental analysis, ring-substituted acetophenones were electrochemically reduced to form radical anions that then decompose in a manner determined by the ring substituent. Cyclic voltammetry was used to identify the electron-transfer (ET) mechanism, which was an electron transfer followed by a chemical reaction (EC). The product of the reaction was often electroactive (ECE) in the potential window defined by the acetonitrile/Bu4NPF6 solvent/supporting electrolyte. Products of the following decomposition were estimated with computer modeling (DFT) to estimate the likelihood of various decomposition pathways. Selection of the ring substituent or switching potential (Egw) allows the instructor to ask students to assign the mechanism for a single reduction or a complete ET mechanism, matching the difficulty of this experiment to the level of audience preparation.