The effect of inorganic salts on the ketone decomposition of oxaloacetic acid.

Oxaloacetic acid is known to decompose in aqueous solution into pyruvic acid and CO2. AtpH 4 and 200 the rate of the 'ketone decomposition' varies between 6 and 18% per hr. The fact that this 'spontaneous' decomposition shows considerable variations suggests that trace impurities might affect the stability of oxaloacetic acid. Krampitz & Werkman [1941] recently reported that Mg ions accelerate the decomposition; this makes it probable that the impurities in question are inorganic salts. The effects of various salts on the rate of decomposition were -therefore studied. Oxaloacetic acid was prepared from tartaric acid according to the methods of Wohl & Oesterlin [1901] and Wohl & Claussnef [1907], and recrystallized according to Fenton & Jones [1900]. The rate of decomposition was measured by the manometric determination of the C02 evolution. Table 1 shows that many inorganic salts increase the rate of decomposition. Small quantities, amounting to 0-3% of the oxaloacetic acid added, are in many cases sufficient to produce a pronounced effect. The effect is thus a catalytic one. The data in Table 1 suggest the following details: