凝固点降低法研究某些脂肪胺的自缔合作用

本工作利用计算机技术改进加热式凝固点测量装置的数据采集系统. 改进后装置的混合物凝固点测量再现性为±0.001 K; 溶剂偏摩尔过量自由能测量再现性为±0.1 J.mol~(-1). 用凝固点降低法测量正丙胺、异丙胺、正丁胺, 异丁胺、正戊胺、异戊胺、二乙胺、二异丙胺、三乙胺、三正丁胺分别与苯和对二甲苯构成二元混合物的溶剂活度系数. 并使用一个包含物理相互作用的三参数连续缔合模型拟合实验数据. 结果表明该模型能较好地刻画所研究的二元缔合混合物。

A Thermodynamic Study on Self-Association of Some Aliphatic Amines by Freezing Point Depression

A computer interface technique was applied to the data collecting system of the apparatus for measuring freezing points of mixtures. The sampling of experimental data, the plotting of heating curves and calculating of freezing points and activity coefficients were completed automatically. The apparatus is capable of measuring the freezing point of mixtures with a reproducibility of ±0.001K and the solvent partial molar excess Gibbs free energy with a reproducibility of ±0.1 J mol~(-1).In this paper, the solvent activity coefficients of binary associated mixtures have been measured for n-propylamine, isopropylamine, n-butylamine, isobutylamine, n-amylamine, isoamylamine, diethylamine, diisoproylamine, triethylamine and tributy-lamine in benzene and p-xylene. The mole fraction concentrations of solute are ranged from 0 to 0.1 and 0 to 0.2 for benzene and p-xylene respectively. The solvent activity coefficients for all systems are greater than unity. A modified three parameter association model, which contained a dimerization constant K_2, a formation to treat the experimental activity coefficients. Under the condition of w=0, this three-parameter model is reduced to the ideall association model. It is shown that the association constants K_2 decrease in the following order:Primary>secondary amines>>tertiary aminesA similar order...