Interaction mechanism between the electrochemically produced benzophenone radical-anions and propionaldehyde and isobutyraldehyde

Abstract

The reaction between benzophenone radical-anions produced through electrochemical reduction of benzophenone and propionaldehyde and isobutyraldehyde has been amperometrically and polarographically investigated. The study has been made in dimethylformamide at –30 and –20°C. Owing to the interaction with the aldehydes, 50 % of the benzophenone radical-anions are oxidized to benzophenone. With propionaldehyde the decay of benzophenone radical-anions substantially follows the first-order law with respect to both radical-anions concentration and aldehyde concentration. For isobutyraldehyde the decay depends on radical-anion concentration to a power between one and two and on aldehyde concentration to the first power. Experimental results are interpreted through a kinetic scheme involving a protonic transfer from aldehydes to radical-anions and to dianions formed by disproportionation of benzophenone radical-anions.