Deriving the Turnover Frequency of Aminoxyl-Catalyzed Alcohol Oxidation by Chronoamperometry: An Introduction to Organic Electrocatalysis.

Abstract

Organic electrosynthesis is an increasingly popular tool for driving and probing redox reactions. Recent advances in this field often employ an electrocatalyst to enhance the selectivity and efficiency of electrochemical reactions. A laboratory experiment was developed to introduce students to relevant mechanistic techniques in electrochemistry for analysis of electrocatalytic reactions using aminoxyl-catalyzed alcohol oxidation as a case study. This lab activity employs cyclic voltammetry for qualitative assessment of catalytic turnover prior to introducing students to chronoamperometry, an underutilized technique that facilitates quantitative determination of the rate of catalysis. Students identify and rationalize the important features of reversible electron transfer and a catalytic reaction in a cyclic voltammogram, probe the origin of scan rate effects on these traces, and calculate turnover frequency using a series of chronoamperograms. The method employs safe and readily available reagents: basic aqueous buffer solution, alcohol substrate, and an inexpensive organic aminoxyl catalyst. Student data presented herein were obtained from a course attended by undergraduate students, graduate students, and pharmaceutical chemists.