Isoxazoles 10: Degradation and Enolization Kinetics of 4-Aminoisoxazolyl- 1,2-Naphthoquinone in Basic Aqueous Solution

CRISTINA S. ORTIZ Y M. M. DE BERTORELLO

JOHN WILEY & SONS INC

Año: 1995 p. 783 - 783

he kinetics of enolization and degradation of N-(5-methyl-4-4isoxazolyl)-4-amino-1,2-naphthoquinone (1) was investigated in aqueous solutions over a pH range of 7.30 to 12.25, at 35 C and at constant ionic strength (u=0.5) using reversed-phase HPLC. Pseudo-first-order kinetics was observed throughout the pH range studied. The rate of enolization (ke), the keto-enol equilibrium constant (Kt), and specific base catalysis rate constant (kOH) were determined. Good agreement between the theoretical pH-rate profile and the experimental data supports the proposed transformation process. The average recovery for 1 ant its tautomerization product 2-hydroxy-N-(5-methyl-4-isoxazolyl)-1,4-naphthoquinone 4-imine (2) from mixtures of different composition was evaluated.