Efficient Resolution of Enantiomers by Coupling Preferential Crystallization and Dissolution. Part 1: Experimental Proof of Principle

Abstract

The resolution of enantiomers can be achieved by preferential crystallization as soon as they crystallize as a conglomerate. However, several successive and alternate crystallizations of each enantiomer as well as seeds of both enantiomers are required for this process to be efficient. The performance can be increased by using two tanks coupled via the liquid phase. In one subcooled tank, the crystallization of a single enantiomer is carried out by enantioselective seeding, while a suspension of racemic mixture in equilibrium at the saturation temperature with the liquid phase is present in a second tank. Over the course of the crystallization, the concentration of the seeded enantiomer decreases. Because of the liquid exchange, the crystallizing enantiomer becomes undersaturated in the second tank, leading to its selective dissolution. Crystallization and dissolution continue simultaneously in both tanks until the solid phase in the second tank becomes enantiopure. At this point, both suspensions can be ...