无水烟酸锂的合成、结构表征及热化学性质  

Synthesis,Characterization and Thermochemistry of Anhydrous Lithium Nicotinate

作　　者：淡文彦[1] 邸友莹[1] 杨伟伟[1] 朱琳[1] 孔玉霞[1] 龚树文[1] 何东华[1] 

机构地区：[1]聊城大学化学化工学院,聊城252059

出　　处：《化学学报》2009年第10期1033-1041,共9页Acta Chimica Sinica

基　　金：国家自然科学基金(No.20673050)资助项目

摘　　要：选择分析纯烟酸和一水氢氧化锂为反应物,利用水热合成方法合成了无水烟酸锂.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78～400K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该反应的反应物和生成物在所选溶剂中的溶解焓,从而得到此反应的反应焓为:ΔrHm=-(20.21±0.41)kJ·mol-1.最后,依据Hess定律计算出无水烟酸锂的标准摩尔生成焓为:ΔfHm[Li(C6H4NO2),s]=-(278.29±1.01)kJ·mol-1.Nicotinic acid and lithium hydroxide monohydrate were chosen as the reactants, anhydrous lithium nicotinate was synthesized by the method of hydrothermal synthesis. FTIR and X-ray powder diffraction techniques were applied to characterize its structure. Low-temperature heat capacities of the Li（C6H4NO2）（s） were measured with a small sample precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of the heat capacities as a function of 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 intervals of 5 K. A reasonable thermochemical cycle was designed, and the standard molar enthalpies of dissolution for the reactants and products of the reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter, respectively. In addition, the enthalpy change of the reaction was calculated to be ΔrHm^θ=-（20.21±0.41） kJ·mol^-1 from the data of the above standard molar enthalpies of dissolution. Finally, the standard molar enthalpy of formation of anhydrous lithium nicotinate Li（C6H4NO2）（s） was determined to be ΔfHm^θ[Li（C6H4NO2）, s]=-（278.29±1.01） kJ·mol^-1 in accordance with Hess law.

关 键 词：无水烟酸锂 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：R914[医药卫生—药物化学]