Exploitation of shifts of eutectic compositions in crystallization-based enantioseparation

The provision of pure enantiomers is of increasing importance for the pharmaceutical industry and in biotechnology. In contrast to the chiral approach aiming to develop an asymmetric synthesis of just one of the enantiomers, the racemic approach is based on separating mixtures of the two enantiomers. This paper describes the potential of two-step enantioselective crystallization processes based on exploiting possible shifts of eutectic compositions in the phase diagrams. Analogies to pressure swing azeotropic distillation are elucidated. The embedding of crystallization into hybrid processes capable to provide required initial enrichments is also discussed. Results of several case studies serve for illustration, partly obtained in the frame of the European FP7 project “INTENANT”.