4,6-二甲氧基-2-嘧啶氨基甲酸甲酯的热力学研究  

Thermodynamic Study of Methyl N-(4,6-Dimethoxypyrimidin-2-yl)carbamate

作　　者：邢军[1] 谭志诚[1] 邸友莹[2] 孙晓红[2] 孙立贤[1] 张涛[1] 

机构地区：[1]中国科学院大连化学物理研究所热化学实验室 [2]西北大学化学研究所,西安710069

出　　处：《化学学报》2004年第24期2415-2420,共6页Acta Chimica Sinica

基　　金：国家自然科学基金 (No.2 0 3730 72 )资助项目

摘　　要：用精密自动绝热量热计测定了自行合成并提纯的 4,6 二甲氧基 2 嘧啶氨基甲酸甲酯在 80～ 3 80K温区的摩尔热容 .实验结果表明 ,在 3 45～ 3 60K温区 ,该化合物有一固 -液熔化过程 .经两次重复测定 ,得其熔化温度、摩尔熔化焓以及熔化熵分别为 :(3 5 7 2 0 1± 0 0 80 )K ,(2 6 2 89± 0 0 2 9)kJ·mol-1和 (73 5 97± 0 0 70 )J·mol-1·K-1.通过分步熔化法得到该物质绝对纯样品的熔点为 3 5 7 44 9K .根据热力学关系和热容数据 ,计算出了该化合物相对于标准参考温度 2 98 15K的热力学函数 .用DSC和TG热分析技术在 3 0 0～ 5 0 0K温区对该物质的热力学性质作了进一步研究 ,得到与绝热量热法一致的固-液熔化过程热力学参数 ,并得到该化合物蒸发过程的热力学参数 :沸点为 488 0 6K ,摩尔蒸发焓为 81 73kJ·mol-1.The low-temperature heat capacities of the methyl N-(4, 6-dimethoxypyrimidin-2-yl) carbamate were measured with an automatic adiabatic calorimeter over the temperature range from 80 to 380 K. A solid-liquid phase transition was observed at T-m = (357.201 +/- 0.080) K, and the molar enthalpy and entropy of fusion were determined to he (26.289 +/- 0.029) kJ. mol(-1) and (73.597 +/- 0.070) J.K-1.mol(-1) mol(-1), respectively. The purity, the real melting point (T-1) and the ideal melting point without any impurity or with absolute purity (T-0) of the compound under investigation were determined to be 99.10 mol%, 357.085 and 357.449 K, respectively, through fractional melting method. The thermodynamic functions relative to the reference temperature 298.15 K were derived based on the heat capacity measurements. Further research on thermodynamic properties of this compound was carried out by means of TG-DTG and DSC techniques. The boiling point and the enthalpy of evaporation for the compound were determined to be 488.06 K and 81.73 kJ.mol(-1), respectively.

关 键 词：嘧啶 甲氧基 热力学关系 热力学函数 热容 氨基甲酸甲酯 熔化过程 温区 提纯 化合物 

分 类 号：O642[理学—物理化学]