Enantiomereiden

Enantiomereiden refer to a pair of stereoisomers that are non-superimposable mirror images of each other. This means that if you imagine a mirror between the two enantiomers, one will look exactly like the reflection of the other, but they cannot be perfectly overlaid. This property is similar to how a left hand and a right hand are mirror images but cannot be placed on top of each other in the same orientation.

The term enantiomer comes from the Greek words "enantio" meaning "opposite" and "meros" meaning "part". Enantiomers have identical physical properties such as melting point, boiling point, and density. However, they differ in their interaction with plane-polarized light and in their biological activity.

One enantiomer will rotate plane-polarized light in one direction (e.g., clockwise, denoted by (+)), while its mirror image enantiomer will rotate it by the same amount in the opposite direction (e.g., counterclockwise, denoted by (-)). This phenomenon is known as optical activity.

In biological systems, enantiomers can have vastly different effects. This is because biological molecules, such as enzymes and receptors, are often chiral themselves, meaning they have a specific three-dimensional structure. Consequently, one enantiomer might bind effectively to a receptor and elicit a biological response, while its mirror image might not bind at all or might even have a different effect. This has significant implications in pharmacology, where often only one enantiomer of a drug is therapeutically active, and the other might be inactive or even toxic. The separation of enantiomers is a crucial process in the synthesis and purification of many pharmaceuticals.