Nuclear magnetic resonance study of chelation effects on the rate of proton dissociation from acetyl groups of β-diketones

Abstract

The rate of proton removal from the CH bonds of acetyl groups in the thallium(I) or sodium salts of β-diketones and related compounds is determined by means of NMR measurement of the rate of deuterium incorporation in D 2O. The results are discussed in terms of chelation effect. It is suggested that the rate is decelerated by the effect of resonance in the chelate ring in which the acetyl carbonyl takes part, and that it is accelerated by the electron-withdrawing effect of the metal ion chelated to the acetyl carbonyl group; the former is the more dominant.