右旋布洛芬的低温热容

在80～370 K温度范围内, 用精密自动绝热量热计准确测量了右旋布洛芬的摩尔热容.其固态右旋布洛芬测量值对折和温度XX=f(T)]的拟和方程为:Cp,m(S)=－39.483X4－66.649X3＋95.196X2＋210.84X＋172.98;相应的液态的拟和方程为 :Cp,m(L)=7.191X3＋4.2774X2＋56.365X＋498.5.并计算得到右旋布洛芬相对于室温(298.15 K)的摩尔焓和摩尔熵.右旋布洛芬的熔点为(324.15±0.02) K.基于摩尔热容的测量,还可获得右旋布洛芬的纯度为99.44％.并对右旋布洛芬和消旋布洛芬的热容进行了对比研究.

Low Temperature Heat Capacity of (S)-ibuprofen

Molar heat capacities of (S)-ibuprofen were precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 80 to 370 K. Experimental heat capacities were fitted into a polynomial equation of heat capacities (Cp. m) with reduced temperature (X), X=f(T)]. The polynomial equations for (S) -ibuprofen were Cp, m (s) = - 39. 483 X4 - 66. 649 X3 + 95. 196 X2 + 210. 84 X + 172.98 in solid state and Cp, m (L) =7. 191X3 + 4. 2774X2 + 56. 365 X + 498. 5 in liquid state. The thermodynamic functions relative to the reference temperarure of 298. 15 K, HT - H298. 15 and ST - S298. 15, were derived for the( S)-ibuprofen. A fusion transition at Tm = (324. 15 ±0. 02) K was found from the Cp - T curve. The molar enthalpy and entropy of the fusion transition were determined to mined to be 99.44% on the basis of the heat capacity measurement. Finally, the heat capacities of ( S)-ibuprofen and racemic ibuprofen were compared.