Chemical investigation of decomposition processes of pyrazolidine-3,5-dione derivatives. Part 3. Kinetics and mechanism of degradation of ketazone in aqueous solutions and solid phase.

Kinetics of decomposition of Ketazone were studied in the Britton-Welford buffer solutions under anaerobic conditions, as well as in the solid state. The sequential type of reaction was found and the first order rate constants for hydrolysis (k1) and decarboxylation (k2) processes were calculated by the so-called "subtraction technique". Thermodynamic parameters were used for prediction of ketazone stability at 20 degrees C. S-shaped curves were obtained from the data of solid state kinetic studies. The decomposition products of Ketazone were isolated and identified by means of TLC, elemental analysis, UV and IR spectra and by their appropriate chemical transformations. The mechanisms of decomposition of Ketazone sodium in aqueous solutions and its acidic form in solid state are proposed.