Abstract
As a part of the investigations on the stability of furosemide (4-chloro-N-furfuryl-5-sulfamoylanthranilic acid) (1), acid hydrolysis of 1 was kinetically examined in alcoholwater mixtures. 1 was hydrolyzed with hydrochloric acid in the mixtures to yield 4-chloro-5-sulfamoylanthranilic acid (2) as a main decomposition product, and this degradation of 1 proceeded in pseudo first-order reaction. The hydrolysis rate constant (kobs), when determined at various values of ionic strength (μ), dielectric constant (D) and temperature (T), became greater as these parameters were raised. The activation energies at μ=0.5 and D=55, calculated by Arrhenius equation, were 34.0 kcal/mol in a methanol-water mixture and 39.7 kcal/mol in an ethanol-water mixture. The half-lives (t1/2) at 20°were 19 days and 79 days in methanol-and ethanol-water mixtures, respectively.
