Separation of FTC-ester enantiomers using a simulated moving bed

A simulated moving bed (SMB) process has been developed for the resolution of racemic mixtures of cis-(+/-)-FTC-ester, a precursor of a potential anti-HIV drug. Chiralpak AD was chosen as the stationary phase and methanol as the mobile phase for this study. The nonlinear standing wave design method was used to determine the zone flow rates and step times of the SMB process. Computer simulations and several laboratory-scale SMB experiments were conducted to test the proposed SMB processes. Extracolumn dead volume (DV) had significant effects on the performance of the laboratory-scale SMB with small columns (10 x 1 cm). Nonuniformly distributed DV was considered in the design and simulations. Different pump arrangements were investigated to reduce the DV effects. High purity (99.8%, or 99.6% e.e.) and high yield (98.9%) were achieved in the SMB experiments. If mass-transfer effects were ignored in the design, the yield would have been lower than 93%.