无水烟酸钾的合成、表征及热化学  

Synthesis, Characterization and Thermochemistry of Anhydrous Potassium Nicotinate

作　　者：孔玉霞[1] 李月宝[1] 杨伟伟[1] 邸友莹[1] 史全[2] 谭志诚[2] 

机构地区：[1]聊城大学化学化工学院 ,聊城252059 [2]中国科学院大连化学物理研究所热化学实验室, 大连116023

出　　处：《化学学报》2008年第6期609-616,共8页Acta Chimica Sinica

基　　金：国家自然科学基金(No.20673050)资助项目

摘　　要：选择分析纯烟酸和无水醋酸钾为反应物,利用室温固相合成方法,合成了无水烟酸钾.利用FTIR和X射线粉末衍射等方法表征了它的结构.用精密自动绝热热量计测定了它在77～400K温区的低温热容,将该温区的摩尔热容实验值用最小二乘法拟合,得到热容随温度变化的多项式方程.用此方程进行数值积分,得到此温区内每隔5K的舒平热容值和相对于298.15K时的各种热力学函数值.在此基础上,通过设计合理的热化学循环,利用等温环境溶解-反应热量计分别测定固相反应的反应物和生成物在所选溶剂中的溶解焓,从而得到该固相反应的反应焓为ΔrHm=(25.87±0.47)kJ·mol-1.最后,依据Hess定律计算出烟酸钾的标准摩尔生成焓为ΔfHm[K(C6H4NO2),s]=-(560.57±1.09)kJ·mol-1.Nicotinic acid and anhydrous potassium acetate were chosen as the reactants, and a novel compound—anhydrous potassium nicotinate was synthesized by the method of room temperature solid phase synthesis. FTIR and X-ray powder diffraction techniques were applied to characterize its structure. Low-temperature heat capacities of the K（C6H4NO2）（s） were measured with a small sample precision automated adiabatic calorimeter over the temperature range from 77 to 400 K. A polynomial equation of the heat capacities as a function of the temperature was fitted by the least square method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at the interval of 5 K. A reasonable thermochemical cycle was designed, and the standard molar enthalpies of dissolution for the reactants and products of the solid phase reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter, respectively. In addition, the enthalpy change of the solid phase reaction was calculated to be Δ r Hm= （25.87±0.47） kJ·mol-1 from the data of the above standard molar enthalpies of dissolution. Finally, the standard molar enthalpy of formation of anhydrous potassium nicotinate K（C6H4NO2）（s） was determined to be Δ f Hm K（C 6 H 4 NO 2）, s=-（560.57±1.09） kJ·mol-1 in accordance with Hess law.

关 键 词：无水烟酸钾 绝热量热法 低温热容 等温环境溶解-反应量热法 标准摩尔生成焓 

分 类 号：TQ464.4[化学工程—制药化工]