阿司匹林固体分解动力学规律

KINETICS OF SOLID-STATE DECOMPOSITION OF ASPIRIN

本文研究了阿司匹林在85、80、75和70℃及不同相对湿度下的固体分解动力学规律。阿司匹林的分解曲线呈反S型,可用幂定律x=kt^n表示,k与温度和相对湿度有关,n值为2,水蒸气对阿司匹林分解的影响较大。在用Arrhenius式时,加入水蒸气压的修正项k=A·e^(-E/RT)·P^s,并由此求得阿司匹林固体分解活化能为122.17kJ/mol(29.2 kcal/mol)。

The kinetics of the solid-state decompo-sition of aspirin was studied at 85°, 80°, 75°,70℃ and various relative humidities. De-composition percentage of aspirin (x) andtime (t)could be described by the equa-tion: x=kt^nwhere k is a constant which depends on thetemperature and relative humidity. The wa-ter vapour pressure effected on the solid-state decomposition of aspirin may be pre-sented by the Arrhenius equation: k=A·exp (-E/RT) ·P^swhere T is the absolute temperature, P iswater vapour pressure, s is a constant, R isthe gas constant, A is another constant, Eis the activation energy. From this equa-tion, the activation energy of the decom-position of aspirin is calculated to be122.17kJ·mol^(-1) (29.2 kcal·mol^(-)).