吡啶-2,6-二甲酸氢钾的合成、结构表征及热化学性质

合成了吡啶-2,6-二甲酸氢钾(KHDPC). 利用X射线单晶衍射仪确定了化合物的晶体结构. 用精密自动绝热热量计测量了其在78~360 K温度区间的低温热容. 利用最小二乘法对配合物的实验热容进行拟合, 得到热容随温度变化的多项式方程. 利用此方程计算出温度区间内的舒平热容值及相对于298.15 K时的热力学函数值. 利用Hess定律设计合理的热化学循环, 在等温环境下利用溶解-反应热量计分别测定所设计热化学反应的反应物和产物在所选溶剂中的溶解焓并计算出反应的反应焓. 最后, 计算出该化合物的标准摩尔生成焓为-(1052.69±1.52) kJ/mol.

Synthesis,Structure Characterization and Thermochemistry of Pyridine-2,6-dicarboxylic Acid Potassium Hydrogen

Pyridine-2,6-dicarboxylic acid potassium hydrogen(KHDPC) was synthesized and its crystal structure was determined by single crystal X-ray diffraction.Low-temperature heat capacities of the compound were measured with an automated adiabatic calorimeter over the temperature range from 78 K to 360 K.Experimental heat capacities were fitted by least-squares method and a polynomial equation of heat capacities vs.reduced temperature was obtained.The smoothed molar heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated based on the fitted polynomial equation.A reasonable thermochemical cycle was designed on the basis of a designed reaction of the substance,and standard molar enthalpies of dissolution for the reactants and products of the supposed reaction in the selected solvents were measured by an isoperibol solution-reaction calorimeter,respectively.Eventually,standard molar enthalpy of formation of the compound was derived to be-(1052.69±1.52) kJ/mol by Hess thermochemical cycle.