Separation of Heterocyclic Compounds by High Pressure Crystallization. (I).

High pressure crystallization has been applied to the separation of indole from the indole-isoquinoline system. Indole with 98.1% purity was obtained at 50°C under 92MPa with the depressurization sweating technique. Equilibrium property of the present system under high pressure was also discussed. Formation of addition compound of indole with isoquinoline was observed in this system. Under higher pressure, the formation range of the addition compound was reduced and the collection range of pure indole or isoquinoline was enlarged very much.