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Abstract

Enantiomers are pairwise occurring molecules, which are non-superimposable mirror images one of the other. Due to homochirality of life, there is a large interest and need to produce pure enantiomers in the pharmaceutical, fine chemical, food and agrochemical industries. Their provision is a challenging task since standard non-selective chemical synthesis always leads to racemic (50:50) mixtures and there is tremendous interest in the mentioned industries to develop innovative methods allowing for a faster access to pure enantiomers. The simplest but rare case that the chiral compound crystallizes as a conglomerate, it is most attractive to apply directly preferential crystallization. However, more frequently racemic compounds are formed during crystallization from racemic feed mixtures. In these cases an initial enrichment is required prior to crystallizing a pure anantiomer. This enrichment might be provided by a partially selective synthesis or can be generated by an initial alternative separation process. The presentation will summarize results of several case studies devoted to combine membrane separation and preparative chromatography with subsequent enantioselective crystallization. The specific degree of enrichment required for successful crystallization was specified always based on preliminary measurements of ternary phase diagrams.