Studies on enantioselective liquid-liquid extraction of amino-(4-nitro-phenyl)-acetic acid enantiomers: modeling and optimization.

BINAP-metal complexes were prepared as extractant for enantioselective liquid-liquid extraction (ELLE) of amino-(4-nitro-phenyl)-acetic acid (NPA) enantiomers. The influence of process variables, including types of organic solvents and metal precursor, concentration of ligand, pH, and temperature on the efficiency of the extraction, were investigated experimentally. An interfacial reaction model was established for insightful understanding of the chiral extraction process. Important parameters required for the model were determined. The experimental data were compared with model predictions to verify the model prediction, It was found that the interfacial reaction model predicted the experimental results accurately. By modeling and experiment, an optimal extraction condition with pH of 7 and host (extractant) concentration of 1 mmol/L was obtained and high enantioselectivity (αop ) of 3.86 and performance factor (pf) of 0.1949 were achieved.