The Effect of Aromatic Amines on the Catalyzed Decarboxylation of 3-Oxo-glutaric Acid

Abstract

Equilibrium constants have been measured for the formation of MA species, where M is divalent manganese, cobalt, nickel, or zinc, and A2− is the 3-oxo-glutarate ion. Equilibrium constants have also been measured for the reactions [Formula: see text], where B is 2,2′-bipyridyl or 1,10-phenanthroline. These constants were obtained by pH measurements at 25 °C and an ionic strength of 0.60. The results are compared with those for similar systems, especially as regards the tendency to form ternary mixed complexes of the type MAB.The rates of decarboxylation of the various MA and MAB species have been measured. The resulting rate constants follow the Irving–Williams order for stability constants, except that in both MAB species the cobalt compound decomposed slightly faster than the nickel compound. The aromatic base, which had been found earlier to have very little effect in copper complexes, increased the rate constants appreciably with other metals, especially with manganese and zinc. Usually 1,10-phenanthroline has a larger effect than 2,2′-bipyridyl. Some possible explanations of the results are considered.