SIMULTANEOUS DETERMINATION OF REVERSIBLE POTENTIAL AND RATE CONSTANT FOR A 1ST-ORDER EC REACTION BY POTENTIAL DEPENDENT CHRONOAMPEROMETRY

When potential step experiments are performed at potentials in the region of the reversible E1/2 for EC type systems, the current vs. time decay is dependent both on the applied potential and the rate constant for the homogenous reaction subsequent to charge transfer. Provided charge transfer equilibrium is established rapidly relative to the chemical reaction, both the reversible E1/2 and the rate constant may be determined by applying curve fitting procedures to the current vs. time transient. A simplex optimization procedure was evaluated using the benzidine rearrangement as a test system, and the accuracies of the determinations of E1/2r and k compare well with other electrochemical techniques. The advantage of the present approach, in addition to the ability to determine E1/2r and K simultaneously, is a large expansion in experimental time frame over other methods. Experiments lasting many times longer than the homogeneous reaction half life can be used to evaluate E1/2r and k. © 1978, American Chemical Society. All rights reserved.