Separation of citalopram intermediate from its acetate by solvent extraction

A new method to separate citalopram intermediate (diol), one of chiral aromatic amino-alcohols, from its acetate after lipase-catalyzed kinetic resolution using liquid–liquid extraction was developed. Diol was firstly derivatized with anhydrides and then extracted with different solvent systems. The effects of pH and initial diol acetate concentration on the total distribution coefficients of diol acetate were investigated. It was found that succinic anhydride was the best derivative agent and water/toluene was the optimal extraction system. The extraction conditions with initial diol acetate concentration of 10 mmol/L, pH 8.0 were applied to the practical extraction process of the mixture of diol and diol acetate obtained by lipase-catalyzed reaction. After three extraction stages at 25 °C, the purity of diol was 99.5% and the yield achieved 86.2%.