Abstract
The kinetic study at different pH values indicates that the monoanion of oxalacetic acid is the major active species which decarboxylates spontaneously. The decarboxylation of the monoanion is favored by nonpolar solvents. Solvent and isotopic effects suggest that the reaction may proceed via an intramolecular hydrogen-bonded intermediate as an activated complex. Infrared spectra which show the formation of an intramolecular hydrogen bond of oxalacetate in solution are obtained. A plausible mechanism consistent with experimental results is proposed for the spontaneous decarboxylation of oxalacetic acid.