The kinetics of hydrolysis of acetylsalicylic acid (Aspirin) in different polar media

Abstract

The kinetics of hydrolysis of Acetylsalicylic acid (Aspirin) to salicylic acid was followed by the direct spectrophotometric measurement of the amount of salicylic acid produced with time. Salicylic acid was complexed with ferric ion giving a characteristic purple colour (λlm 523nm). The kinetics of hydrolysis was found to follow pseudo first-order reaction. Of the polar solvents studied aspirin was most stable in phosphate buffer (0.1 M, pH7.4) with half-life of 537.21 ± 8.42 hours and least stable in glycerol/water system (half-life, 155.31 ± 2.33 hours). Boric acid buffer (pH 10.4) and 10% dextrose solution hydrolyzed aspirin to the same magnitude (half-life 256.67 ± 2.35 and 261.61 ± 2.306) respectively. Key Words: Aspirin, Hydrolysis, Kinetic studies. Global Jnl Pure & Applied Sciences Vol.10(2) 2004: 297-300