Date of Award
Master of Science in Pharmaceutical Sciences
The effect of ultrasonic energy on the degradation of aspirin in ethanol-water, diethylether-water, and diethylene glycol-water solvent systems has been studied. The concentration ratios of each solvent system was varied and examined at several different temperatures. Aliquots were withdrawn simultaneously from the control and ultrasonified systems, and analyzed spectrophotometrically. It was found that the application of ultrasound to a system undergoing degradation would cause an increase in the rate but the same kinetic order was maintained. The heat of activation was lowered by the mechanical vibrations of the ultrasonic energy. It is postulated that the ultrasonic vibration increases the effect of the movement of molecules toward each other and the movement of the products away from each other on the overall rate of reaction, As the concentration ratio was increased in the diethylene glycolwater system, the subsequent increase in viscosity reduced the effect that ultrasonic vibration had on the movement of molecules.
Needham, Thomas E., "Ultransonic Degradation of Aspirin in Mixed Solvent Systems" (1967). Open Access Master's Theses. Paper 211.