Abstract:

The kinetics of aspirin hydrolysis is the critical content of theoretical physical chemistry for both medical and pharmaceutical students. The experiment is usually conducted by monitoring aspirin's hydrolysis product (salicylic acid, SA) with a spectrophotometer after reaction with soluble Fe³⁺ salts. However, the kinetic measurement of aspirin hydrolysis has not been widely implemented in physical chemistry laboratory, because of the complicated procedures and the long testing period required to perform the reaction. In this work, the ultraviolet absorbance of SA at a wavelength of 296 nm has been employed to determine the kinetics of aspirin hydrolysis in a phosphate buffer (pH = 6.85). Compared with the traditional method, these improvements simplify the experimental procedures significantly, avoid the formation of liquid acidic wastes, and shorten the reaction time, thus, turn the hydrolysis of aspirin into a practical kinetic experiment for medical and pharmaceutical college students.

Key words: Aspirin, Acetylsalicylic acid, Hydrolysis, Kinetics, Spectrophotometry