Inhibition of Homogeneous Reactions by Small Quantities of Nitric Oxide

Abstract

THERE is convincing evidence that some chemical changes take place by a mechanism involving reaction chains of considerable length, and equally convincing evidence that in other reactions no such long chains occur. Nearly every chemical reaction, however, starts by the activation of certain molecules, that is, by considerable highly localised thermodynamic fluctuations, and in principle it is possible that some of these fluctuations are intense enough for their influence to persist through several cycles of chemical change, giving rise to the effect of very short chains, although the normal characteristics of a chain reaction would not be exhibited. This point of view has been emphasised by Semenov at the end of his recent book. Either the fluctuation is simply an accumulation of energy, or, in accordance with a widely held modern view, it leads to the escape of free radicles. These are thermodynamically unstable, and must at once, or after a greater or smaller interval of time, disappear from the system.