Purification of organic crystals by high-pressure sweating

The effect of high pressure combined with a sweating technique was studied in purification of organic crystalline chemicals. The dependence of product purity and yield on pressure, pressing period, and mass of charge were determined. Mixtures studied were guaiacol glycerin ether with guaiacol as impurity and naphthalene with diphenyl as impurity. Purity of these mixtures was in both cases about 90 wt%. The mixtures were placed at an elevated pressure close to their equilibrium liquidus point. The purity of 98 wt% was achieved by using pressures between 300-700 bar and pressing periods of 20 and 40 min. Yield of the purified compound was higher than 80%.