Isoxazoles VII. Hydrolysis of 4-Methyl-5-Isoxazolyl-naphthoquinone Derivatives in Aqueous Solutions

LONGHI MARCELA, BERTORELLO MARÍA, AND BRIÑÓN MARGARITA

JOURNAL OF PHARMACEUTICAL SCIENCES

John Willey & Sons

Lugar: New York, USA.; Año: 1991 vol. 80 p. 573 - 573

0022-3549

p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 90pt; TEXT-INDENT: -54pt; TEXT-ALIGN: justify; tab-stops: 7.2pt 43.2pt 79.2pt 115.2pt 151.2pt 187.2pt 223.2pt 259.2pt 295.2pt 331.2pt">The kinetics for the degradation of 2-(methyl-5-isoxazolylamine)-N-(4-methyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (1) in solution were investigated at 70 ºC and at constant ionic strength of 0.5 over a pH range of 1.75 to 12.85. The degradation rates were determined by absorption and second-derivative UV spectrometry. Two degradation products were identified in acidic and neutral pHs; they are 4-N-(4-methy-5-isoxazolyl)-1,2-naphthoquinone (2) and 2-methyl-cyanoacetamide (5), respectively. In alkaline pH, two degradation products, 2-hydroxy-N-(4-methyl-5-isoxazolyl)-1,4-napthhoquinone-4-imine (3) and 5-amino-4-methylisoxazole (4) were isolated. The pathway for degradation of 1 in acidic and neutra