On the mechanism of oxidation-reduction potential

Abstract

The phenomena of oxidation-reduction potential are becoming increasingly important in the study of biological oxidation processes. Unfortunately, however, the application of the results obtained from studies on potential to such processes has been somewhat hindered by the fact that the study of potential phenomena has up to the present been approached from a point of view which differs considerably from that of the more important theories of the mechanism of biological oxidation processes. The conceptions used in the development of the two subjects have been different, and the close connection between the two sets of phenomena has thereby been obscured. For instance, Wieland’s theory, which has played such an important part in the development of the subject of biological oxidation processes, is founded on the conception of activation and transfer of hydrogen atoms, while Mansfield Clark, in his recent important and valuable studies on reduction-potential, makes use of conceptions such as electron activity, transfer of “ electron pairs,” and so on. This absence of “ linking up ” between the two sides of the subject has, in fact, been brought up as an objection to the Wieland view. For instance, Clark (3, 4) claims that the reduction-potential phenomena prove that the oxidation-reduction process consists essentially in the transfer of an electron pair from reductant to oxidant, and not in the transfer of hydrogen as assumed by Wieland. He regards this as a very serious objection to the Wieland theory, although possibly not sufficient entirely to disprove it. It must be pointed out, however, that the fact that the electron transfer hypothesis leads to correct results is no proof of its truth until the alternative hypotheses have been shown to yield incorrect results. In the present communication it is shown that the Wieland view also leads to correct results ; in fact, it is possible to predict the reduction-potential phenomena from the work of Wieland. This at once disposes of one of the main objections to Wieland’s theory and renders it possible to relate the mechanism of oxidation-reduction potential with that of biological oxidation-reduction processes.