Kinetic studies of the uncatalysed and metal-ion catalysed decarboxylation of acetonedicarboxylic acid

Abstract

The decarboxylation of β -keto acids is of considerable importance in biochemical systems and also from the point of view of reaction mechanism studies. β -keto acids decompose spontaneously in aqueous solution, liberating carbon dioxide, and both the free acid and anion may decarboxylate so that the rate equation is of the form where k1 and k2 are the first order rate constants for the acid and anion respectively. The decarboxylation of the acid and anion can be represented, in which an enol intermediate is first produced and then ketonises. The ready decarboxylation of these acids is understandable due to the presence of the electron-withdrawing carbonyl group. Other acids containing electron-withdrawing substituents such as nitroacetic acid, chloroacetic acid and picolinic acid also decarboxylate quite readily in solution B. R. Brown, Quart. Revs. ,5, 131 (1951)., J Hine, "Physical Organic Chemistry", p.302, McGraw-Hill Book Co., Inc., N.Y., 1962.