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Abstract

In part 1 of this work, the potential of chiral solvents in enantioseparation was studied for two pharmaceutical substances with regard to thermodynamics (Cryst. Growth Des. 2008, 8, 3408−3414). Unfortunately, no measurable chiral recognition in terms of the solubility equilibria was observed between the chiral solvents and the chiral systems investigated. In this part 2, studies are directed toward the potential of chiral solvents in enantioseparation based on differences in crystallization kinetics. For the case study performed, mandelic acid as a racemic compound forming system has been chosen. The crystallization kinetics (metastable zone width data with regard to primary nucleation) determined for mandelic acid in the chiral solvents (S)-ethyl lactate and (2R,3R)-diethyl tartrate are shown and discussed. On that basis successful preferential nucleation/crystallization experiments allowed for racemate resolution. To explain the observed results solvation enthalpy data obtained from dissolution enthalpy measurements are considered. Copyright © 2009 American Chemical Society [accessed March 17, 2009]