Measurement of Melting Temperature of Organic Compounds by Visual Observation Method at High Pressures and Calculation of Volume Change on Melting by Using Melting Temperature-pressure Relationship.

The melting temperatures of pyridine, 2-methylindole, 5-methylindole and o-methoxyphenol (guaiacol) were measured at temperatures from 231 to 350 K and pressures up to 500 MPa by a visual observation method. The melting temperatures were increased monotonously with increases in pressures, while the slopes of melting curves, dT/dP, inclined slightly down word. The experimental results of the melting temperatures at high pressures could be successfully expressed by the Simon equation. Volume changes of fusion at normal pressure of 14 kinds of aromatics and carbon tetrachloride were calculated by using the experimental melting temperatures and heats of fusion.