The Acidities of Ketones and the Mechanism of Prototropic Change

Abstract

The observation of acidity in the brominated acetones is attributed to coordination of carbonyl carbon and hydroxyl ion, the process being preceded by electromeric change to the semipolar form. Acid‐ and base‐catalyzed prototropy is regarded as involving a similar electromeric change, brought about by interaction with the catalyst, and followed by transformation of the semipolar form either to ketone or to enolic ion. The measured velocity will thus be dependent upon (a) the rate of reaction of ketone and catalyst, and (b) the proportion of the semipolar form which changes to enol. The application of this view, in conjunction with the conception of quantum‐mechanical resonance as developed by Pauling, renders possible the satisfactory interpretation of a number of observations relating to the prototropic changes of carbonyl compounds.