Abstract: Objective To research on monitoring synthesis systems of aspirin with sodium acetate as the catalyst. Methods Each standard work curve of aspirin and salicylic acid were established with second derivative value against concentration at the wavelengths of 289 nm and 308 nm. Under different temperatures, the real-time content of aspirin and salicylic acid in synthesis reaction system were monitored. Results When the reaction temperature was 45,55,65 and 75℃, the complete reaction times were about 20, 10, 4 and 3 min individually. Conclusion The length of the synthesis of aspirin reaction time was significantly shorter with the higher reaction temperature by using sodium acetate as catalyst. The ultraviolet absorption and derivative spectrometry can be achieved on the monitoring and judging aspirin synthesis reaction endpoint.

Key words: aspirin, sodium acetate, ultraviolet absorption spectrum, second derivative spectrum