Nobuhiko Nishiguchi

Separation of high purity indole from coal tar by high pressure crystallization

Abstract 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−2 from 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.

Effect of pressure on the solid-liquid phase equilibria of binary organic systems

Solid-liquid phase equilibria of the binary mixtures of the organic liquids have been investigated at temperatures from 278 to 343 K and pressures up to 500 MPa using a high-pressure optical vessel. The systems investigated are as follows: (1) simple eutectic systems-benzene + cyclohexane system and benzene + 2-methyl-2-propanol system; (2) eutectic systems with formation of intermolecular compounds — carbon tetrachloride + p-xylene system and carbon tetrachloride + benzene system; (3) partial solid solution system-α-methylnaphthalene + β-methylnaphthalene system; and (4) complete solid solution system-chlorobenzene + bromobenzene system. The uncertainties of the measurements of temperature, pressure and composition are within ±0.1 K, ± 0.5 MPa, and ±0.001 mole fraction, respectively. The freezing and melting temperatures at a constant composition increase monotonously with pressure. The eutectic mixture becomes richer in the component whose temperature coefficient of the freezing pressure is larger and the eutectic temperature rises monotonously with increasing pressure in the eutectic systems. The pressure-temperature-composition relation of the solid-liquid phase equilibria can be expressed satisfactorily by an equation newly proposed.

in-situ Observation of crystal growth of p-xylene from p-, m-mixtures by application of very high pressure

Abstract Experiments of in-situ observation of p-xylene crystal growth were carried out under very high pressure. Based on these results, the crystal habit and the growth rate in relation to the p-xylene concentration and to supersaturation pressure are discussed. The growth rate determining factor changes with mother liquor concentration.

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.