Electrode Kinetic Studies on Electro‐organic Syntheses Involving Carbonium Ions: II . Anodic Oxidation of Acetate Ions in Presence of Dimethylformamide

Abstract

The anodic oxidation of acetate ions in (nominally nonaqueous) glacial acetic acid and in glacial acetic acid‐dimethylformamide solutions has been examined on platinum at various temperatures between 25° and 75°C. Potentiostatic and potentiodynamic techniques were used in conjunction with reaction product analysis by infrared and NMR. The real heat of activation at the reversible potential for the Kolbe reaction in glacial acetic acid is 53 kcal mole−1. Also, acetate ions can undergo oxidation at low potentials (e.g., 0.45V vs. RHE) when the reaction is carried out at a high temperature (ca. 75°C). The oxidation of DMF is indicated around 1.1–1.5V at temperature above 55°C, both in potentiostatic and potentiodynamic profiles. The product analysis shows that oxidation of DMF also occurs at high potentials (e.g., 2.37V) in parallel to the Kolbe reaction. The product of DMF oxidation at this potential is N‐acetoxymethyl N′‐methylformamide; the coulombic efficiency for the formation of this product at 2.37V is about 5%.