MELTING TEMPERATURES OF SEVERAL POLYCYCLIC AND HETEROPOLYCYCLIC AROMATIC-COMPOUNDS UNDER HIGH-PRESSURES

Melting temperatures of several polycyclic and heteropolycyclic aromatic compounds have been measured in the pressure range 0.1-350 MPa and in the temperature range up to 350 K with a direct visual observation method. The polycyclic aromatic compounds measured were 1-methylnaphthalene, 2-methylnaphthalene, diphenyl, while the heteropolycyclic aromatic compounds measured were quinoline. isoquinoline, 2-methylquinoline, indole and thianaphthene. In order to test the validity of the experimental method, the melting temperatures of benzene, cyclohexane and carbon tetrachloride have also been determined and compared with literature data. It is found that there is a fair agreement between the present results and some of the literature data. In the case of quinoline, two melting lines were observed which indicates that two solid forms of quinoline exist. The triple point of the liquid-liquid-solid equilibria of quinoline was found to be at 296.3 K and at 179.6 MPa. The experimental results were fitted to the Simon equation for melting.