Melting temperatures for o-methoxyphenol-indole and thianaphthene-indole systems under high pressure

Melting temperatures for o-methoxyphenol-indole and thianaphthene-indole systems under high pressures were measured using the visual observation method. Liquidus curves were determined from the melting temperature-pressure relationships obtained. From the results, a simple eutectic phase diagram was confirmed for the o-methoxyphenol-indole system. The composition range in which indole precipitated was widened gradually with increasing pressure. Higher yields of solid indole were then expected for high pressure crystallization processes. The polymorphism of o-methoxyphenol crystal was also observed. On the other hand, a complete solid solution formation system was confirmed for the thianaphthene-indole system. Therefore, based on the results, recrystallization was required to obtain high purity indole from multicomponent mixtures containing considerable amounts of thianaphthene.