Solid-Liquid Phase Equilibria of Organic Compounds Under High Pressures

用新设计的高压光学容器，在278~343K温度和500 Mpa压力下，研究了有机化合物二元混合物的固液相平衡。1)简单共熔体系：苯+环己烷、苯+2-甲基-2-丙醇体系(2)形成分子间化合物的体系：四氯化碳+苯、四氯化碳+对二甲苯(3)部分固溶体体系：-甲基萘+-甲基萘(4)完全固溶体体系：氯苯+溴苯2装置和实验程序。将已知组成的样品液体放入平衡罐中，浸泡在恒温控制在0.05K内的液浴中，然后逐步压缩。3实验结果与讨论在所有相图中，恒定组成下的冻结温度均随压力的升高而单调升高。共晶温度向更高温度移动，共晶成分向冻结温度压力系数越大的成分越丰富。在形成分子间化合物的体系中，发现同一组分的熔点转变为不同组分的熔点，在高压下一种化合物消失。固-液共存曲线可用新提出的适用于所有体系的方程进行关联。

Solid-liquid phase equilibria of the binary mixtures of organic compounds have been investigated at temperatures from 278 to 343 K and pressures up to 500 MPa using a high-pressure optical vessel newly designed. The uncertainties in the measurements of temperature, pressure and composition are within 0.1 K, 0.5 MPa and 0.001 mole fraction, respectively.1 Systems investigated(1) simple eutectic systems : benzene + cyclohexane, benzene + 2-methyl-2-propanol(2) systems with formation of intermolecular compounds : carbon tetrachloride + benzene, carbon tetrachloride + p-xylene(3) partial solid solution system : -methylnaphthalene + -methylnaphthalene(4) complete solid solution system : chlorobenzene + bromobenzene2 Apparatus and experimental proceduresThe measurements were performed in a high-pressure vessel with a couple of optical windows. The sample liquid of a known composition was introduced in the equilibrium vessel, which was immersed in a liquid bath thermostatically controlled within 0.05 K, and was compressed gradually. The phase transition and solid-liquid coexistence were observed visually.3 Experimental results and discussionThe freezing temperature at a constant composition increases monotonously with increasing pressure in all cases of phase diagrams. The eutectic temperature shifts to higher temperature, and the eutectic composition shifts to richer composition of the component whose pressure coefficient of freezing temperature is larger. In the systems forming intermolecular compounds, it is found that the congruent melting point turns to the incongruent melting point, and that one compound disappears under high pressure. The solid-liquid coexistence curve can be correlated satisfactorily by an equation newly proposed for all systems.