New Enabling Chiral Crystallization Technologies – Transformation of Racemates into Pure Enantiomers

In recent years a renaissance in chiral crystallization technologies has enabled the complete deracemization of chiral compounds. Attrition-enhanced deracemization (Viedma ripening) and temperature cycling induced deracemization (TCID) technologies have been developed by which the solid phase of racemic mixtures can be transformed into the desired pure enantiomer in a sustainable manner. No additional chiral auxiliaries are needed and by recycling of the racemizing mother liquor complete conversion can be achieved. In this paper the requirements for these new technologies will be discussed and an overview of the applications will be presented, with emphasis on pharmaceutically interesting compounds.