Continuous Chiral Inversion by Coupling Enzymatic Racemization with Enantioselective Fluidized Bed Crystallization

In this study, the continuous chiral inversion of an undesired but cheap and readily available enantiomer into a desired valuable target enantiomer via coupling enzymatic racemization with preferential crystallization is investigated and experimentally demonstrated. Two different process configurations for coupling a racemization fixed-bed reactor with enantioselective fluidized bed crystallization are first theoretically studied using a developed process model. The results suggest that coupling racemization with a two-stage enantioselective fluidized bed crystallization allows for efficient enzyme utilization. Subsequent experiments performed in pilot plant scale led to successful, efficient, and robust continuous chiral inversion. An attractive continuous chiral inversion was achieved with a productivity of about 25 g/L/h and chiral purities > 98%.