Isoxazoles 9: Degradation Kinetics of 4-(Isoxazolylamino)-1,2-naphthoquinone in Acidic Aqueous Solution

CRISTINA S. ORTIZ Y M. M. DE BERTORELLO

JOHN WILEY & SONS INC

Año: 1994 p. 1457 - 1457

he degradation kinetics of N-(5-methyl-4-isoxazolyl)-4-amino-1,2-naphthoquinone (1) was studied in aqueous solution over a pH range of 0.65-7.50, at 35 C and at a constant ionic strength of 0.5. The degradationrates were determined by high-pressure liquid chromatography and were observed to follow pseudo-first-order kinetics with respect to the concentration of 1. The pH-rate profile was linear slope -1 under acidic pH, becoming pH independent from 3.50 to 7.50. Good agreement between the theoretical pH-rate profile and the experimental data supports the proposed degradation process. The catalytic rate constant for hydrogen ion and water were kH=0.901 M-1 h-1 and ko=1.34x10-3 h-1, respectively. These data arre appropriate to develop a stable dosage from of 1. The accuracy, peak sharpness, and asysmmetry focator for the analytical method were determined.