Chiral separation of systems of high eutectic composition by a combined process: Case study of serine enantiomers

A concept for the chiral resolution of racemic compounds by a combination of chiral pre-enrichment by continuous multi-column chromatography and final purification using selective crystallization is presented. The system of serine enantiomers in water represents a typical racemic compound-forming system with very high eutectic compositions in the chiral system, which is generally considered as unfavorable for selective crystallization. It is shown exemplarily, how the solvent and temperature-dependent formation of hydrates can be exploited to allow efficient chiral resolution by a combined process for this and similar systems.

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► Optimized coupling of SMB chromatography and selective crystallization.
► Alcohols suppress the formation of l-serine monohydrate.
► Eutectic composition depends of the solid state (hydrous/anhydrous) of l-serine.
► Purposeful shift of the eutectic composition exploited for chiral resolution.