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Abstract:
Multistage crystallization has been used for resolution of the racemic mixture of citalopram to obtain pure S-citalopram. The racemate was converted to a diasteromeric salt pair using (+)-O,O′-di-p-toluoyl-d-tartaric acid, (+)DTT, as a resolving agent. The obtained salts involved solid solutions almost within the entire range of the crystalline phase composition, which excluded the possibility of a single-stage resolution. Therefore, a multistep crystallization technique was employed that allowed enrichment of the racemate with the desired diastereomer in the liquid phase. Moreover, a procedure for restoring the 1:1 composition of the depleted solid phase has been developed. The procedure was based on formation of a diasteromeric salt pair with the opposite enantiomer of the resolving agent, i.e., (−)DTT.
Copyright © 2012 American Chemical Society
