Fractional reactive extraction for symmetrical separation of 4-nitro-D,L-phenylalanine in centrifugal contactor separators: experiments and modeling.

The enantioselective liquid-liquid extraction of 4-nitro-D,L-phenylalanine (D,L-Nphy) using PdCl2{(s)-BINAP} as extractant in dichloroethane was studied experimentally in a countercurrent cascade of 10 centrifugal contactor separators (CCSs) at 5 degrees C, involving flow ratio, extractant concentration, and Cl- concentration. The steady-state enantiomeric excess (ee) in both stream exits was 90.86% at a 93.29% yield. The predicted value was modeled using an equilibrium stage approach. The correlation between model and experiment was satisfactory. The model was applied to optimize the production of both enantiomers in >97% ee and >99% ee. 14 stages and 16 stages are required for 97% ee and 99% ee for both enantiomers, respectively. Chirality 27:75-81, 2015. (c) 2014 Wiley Periodicals, Inc.