α-Hydroxyacetoacetic acid

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Abstract
Solns. containing equiv. amts. of a-hydroxyacetoacetic and acetic acids were prepared by the anaerobic hydrolysis of ethyl a-acetylhydroxyacetoacetate in dilute alkali. The stability of hydroxyacetoacetic acid in aq. soln., pH 7.4, and 4.6 was detd. at 25 and 37.5[degree]. Ethyl hydroxyacetoacetate was oxidized in [image]/10 NaHCO3 by molecular O2. In the process 1 mol. O2 was absorbed and 1 mol. acetic acid and 1 mol. ethyl hydrogen oxalate were formed. In the oxidation of hydroxyacetoacetic acid by molecular O2 in [image]/10 NaOH 1 mol. O2 was absorbed and 1 mol. CO3, 1 mol. formic acid and 1 mol. acetic acid were produced. The latter apeared as a polymerization product of the CH3[long dash]CO[long dash]moiety which yielded acetic acid quantitatively after heating with acid. The velocity of oxidation (in many cases a measure of the tendency to enolization) was of the following order: ethyl hydroxyacetoacetate > hydroxyacetoacetic acid > acetol. A no. of oxidation reactions were studied manometrically. A method of estimating acetol by reduction is described. No effect on the respiration of rat tissues could with certainty be attributed to hydroxyaceto-acetic acid. A possibly oxidative removal was observed only with liver and heart; with kidney slices the only effect was rapid decarboxylation. When acetoacetic acid was incubated anaerobically with rat tissues a dismutation took place, since the [beta]-hydroxybutyric acid formed accounted for only 50% of the acetoacetic acid disappearing. No evidence was found which would allow identification of the oxidative equivalent with hydroxyacetoacetic acid. dl-Threo-l:2-dihydroxybutyric acid was oxidized by slices of rat kidney to hydroxyacetoacetic acid in amt. which accounted for about 50% of the dihydroxybutyric acid disappearing. This proved that the failure to detect hydroxyacetoacetic acid among the oxidation products of acetoacetic acid was not due to a too rapid disappearance of hydroxyacetoacetic acid or to inadequate technique of detection.

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