Enantioeristäminen

Enantioeristäminen, also known as enantiomeric separation or chiral resolution, is a process used in chemistry to separate a racemic mixture into its individual enantiomers. A racemic mixture is a solution containing equal amounts of two enantiomers, which are stereoisomers that are non-superimposable mirror images of each other. Enantiomers have identical physical properties, such as melting point and boiling point, except for their interaction with plane-polarized light, where they rotate it in opposite directions.

The separation of enantiomers is crucial because enantiomers can exhibit vastly different biological activities. For instance, one enantiomer of a drug might be therapeutically effective, while the other could be inactive or even harmful. Therefore, obtaining pure enantiomers is often a critical step in the synthesis of pharmaceuticals, agrochemicals, and other chiral compounds.

Several methods are employed for enantioeristäminen. One common technique is chiral chromatography, where a stationary phase containing a chiral selector is used to differentially interact with the enantiomers, leading to their separation as they pass through the column. Another method is diastereomeric salt formation, where the racemic mixture is reacted with a pure chiral resolving agent to form diastereomeric salts. Diastereomers have different physical properties, allowing for their separation by crystallization. After separation, the resolving agent is cleaved to regenerate the pure enantiomers. Enzymatic resolution, using enzymes that selectively react with one enantiomer, is also a widely used approach. Crystallization and kinetic resolution are other methods employed to achieve enantiomeric separation. The choice of method depends on the specific compound and the desired purity.