High pressure crystallization has been applied to the separation and purification of indole from a model mixture of crude coal tar. Indole with 98.6 wt% purity was separated at 50 °C under a pressure of 2000 kgf cm-2from the model mixture contaning 69.3 wt% indole. Successive 'depressurization sweating' increased the purity of indole up to 99.5 wt%. The equilibrium of the system under high pressure was also studied. © 1991.
Yamamoto, Y., Sato, Y., Ebina, T., Yokoyama, C., Takahasi, S., Mito, Y., … Nagaoka, K. (1991). Separation of high purity indole from coal tar by high pressure crystallization. Fuel, 70(4), 565–566. https://doi.org/10.1016/0016-2361(91)90039-D