1,4-Dioxan-2-one, 1, was synthesized and the equilibrium constant between it and the hydrolysis product 2-(2-hydroxyethoxy) acetic acid, 2, was determined as KO = 70 ± 3.5 in acidic aqueous media, 25 °C, ionic strength 1M, (KCl), 5% by volume acetonitrile. The carboxylic acid dissociation constant of 2 was determined under the same conditions to be pKa = 3.31 ± 0.02. On the basis of these two determinations, the equilibrium constant between 1 and carboxylic acid anion, 3, and the proton was calculated to be KOA = 0.034 ± 0.002 M. The stability of 1 was determined in the range of pH between 1 and 8.5 in buffered aqueous solutions under the conditions above by UV spectrophotometric methods and exhibited simple first order kinetics of decay. On the basis of buffer dilution plots, the values of ko, the rate constant for solvent mediated decomposition, were determined. The plot of log ko against pH is consistent with a three term rate law for solvolysis with a hydrogen ion catalyzed rate constant kH+ = 1.1 (± 0.1) M−1 min−1, a water catalyzed rate constant, kw = 9.9 (± 0.5) × 10−4 min−1, and a hydroxide ion catalyzed rate constant, kOH = 4.1 (± 0.3) × 104 M−1 min−1. The t1/2 for decay at pH = 7.0, at 25 °C, is ~2 h. Treatment of F344 rats with aflatoxin B1 (AFB1) (positive control) elicited the expected preneoplastic foci in the livers of each rat tested, while subsequent administration of 1 (a total of 1.32 g over 12 weeks) failed to statistically increase focal number or focal volume percent. In 8 rats administered 1 (1.32 g, 12 weeks) alone, no increase above background foci was detected. This study does not support compound 1 as a common carcinogen.
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