Mechanistic aspects of oxidation of loop diuretic drug furosemide by Ag(III) periodate complex in alkali media: A kinetic approach

The kinetics of oxidation of a loop diuretic drug furosemide (Fur) by diperiodatoargentate(III) (DPA) has been investigated spectrophotometrically in alkaline medium at a constant ionic strength of 0.20 mol dm⁻³. The stoichiometry was 1 : 2 (Fur: DPA). The order of the reaction with respect to [DPA] was unity while the order with respect to [Fur] was less than unity over the concentration range studied. The rate increased with increase in [OH⁻] and decreased with increase in [IO₄⁻]. The oxidation products were identified as 2-(4-carboxy-2-oxo-but-3-enylamino)-4-chloro-5-sulfamoyl-benzoic acid and Ag(I). The reaction constants involved in the different steps of the reaction mechanism were calculated. Kinetic experiments suggest that [Ag(H₂IO₆)(H₂O)₂] is the reactive silver(III) species.