The resolution of enantiomers can be achieved by preferentialcrystallizationas soon as they crystallize as a conglomerate. However, several successiveand alternate crystallizations of each enantiomer as well as seedsof both enantiomers are required for this process to be efficient.The performance can be increased by using two tanks coupled via theliquid phase. In one subcooled tank, the crystallization of a singleenantiomer is carried out by enantioselective seeding, while a suspensionof racemic mixture in equilibrium at the saturation temperature withthe liquid phase is present in a second tank. Over the course of thecrystallization, the concentration of the seeded enantiomer decreases.Because of the liquid exchange, the crystallizing enantiomer becomesundersaturated in the second tank, leading to its selective dissolution.Crystallization and dissolution continue simultaneously in both tanksuntil the solid phase in the second tank becomes enantiopure. At thispoint, both suspensions can be filtrated, and each tank yields a pureenantiomer. The proof of principle has been successfully given forthe resolution of dl-threonine. Besides reducing the numberof steps needed to access both pure enantiomers, this process wasfound to be more productive than conventional alternatives of resolutionby preferential crystallization. [ABSTRACT FROM AUTHOR]