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Abstract

Pure enantiomers are of large interest for several industries. Chemical synthesis is frequently not selective and provides racemic mixtures causing a large interest in efficient separation processes. Preparative chromatography is nowadays a powerful and flexible but expensive technology. As an alternative there exists the possibility to apply cheaper crystallization processes. Based on classifying enantiomeric systems according to their type of solid-liquid equilibria, crystallization processes will be discussed which are capable to provide pure enantiomers. Two separation problems studied in our laboratory will be considered for illustration. Preferential crystallization was used to separate racemic threonine and an asymmetric partially enriched mixture of the mandelic acid enantiomers both from an aqueous solution. Using various operation modes and considering the effect of different seed characteristics and a tailor-made additive on the performance of preferential crystallization, the potential of this technique for enantioseparation is highlighted.