2-氨基-4,6-二甲氧基嘧啶的低温热容和热力学性质研究  

Low-Temperature Heat Capacity and Thermodynamic Properties of 2-Amino-4,6-dimethoxypyrimidine

作　　者：孙晓红[1] 宋纪蓉[1] 谭志诚[2] 邸友莹[2] 马海霞[1] 王美涵[2] 孙立贤[2] 

机构地区：[1]西北大学化工学院化学研究所,西安710069 [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》2003年第12期1897-1903,共7页Acta Chimica Sinica

基　　金：国家自然科学基金 (No.2 0 0 730 4 7);陕西省自然科学基金(No.2 0 0 1H1 1 )资助项目

摘　　要：通过精密自动绝热量热计测定了自行合成并提纯的 2 氨基 4,6 二甲氧基嘧啶在 78～ 3 94K温区的摩尔热容 .实验结果表明 ,该化合物有一个固 -液熔化相变 ,其熔化温度、摩尔熔化焓以及摩尔熔化熵分别为 :(3 70 .97± 0 0 2 )K ,(2 985 3 91± 9 2 5 )J·mol-1和 (80 45± 0 0 3 )J·mol-1·K-1.通过分步熔化法得到样品的纯度为 0 9984(摩尔分数 )和绝对纯样品的熔点为 3 71 0 3 1K .在热容测量的基础上计算出了该物质每隔 5K的热力学函数值 .用DSC技术对其固 -液熔化过程作了进一步研究 。The low-temperature heat capacities of 2-amino-4, 6-dimethoxypyrimidine ( C6H9N3O2) were precisely measured by an automated adiabatic calorimeter in the temperature range of 78 to 394 K. The sample was observed to melt at (370.97 +/- 0.02) K. On the basis of the heat-capacity measurements, the molar enthalpy and entropy of the phase transition as well as chemical purity of the substance were determined to be (29853. 91 +/- 9. 25) J (.) mol(-1), (80.45 +/- 0.03) J (.) mol(-1) (.) K-1 and 99.84%, respectively. The thermodynamic function of the compound were derived and reported at an interval of 5 K. The, further research of the melting process for this compound has been carried out by means of DSC technique. The result was in agreement with that. obtained from the measurements of heat capacities.

关 键 词：2-氨基-4 6-二甲氧基嘧啶 低温热容 热力学函数 绝热量热法 差示扫描量热法 纯度测定 农药 除草剂 

分 类 号：O642[理学—物理化学]