enantiomérie

Enantiomerie is a specific type of stereoisomerism where a molecule and its mirror image are non-superimposable. These mirror-image molecules are called enantiomers. For a molecule to exhibit enantiomerie, it must possess at least one chiral center, which is typically a carbon atom bonded to four different atoms or groups. The arrangement of these four groups around the chiral center can be in one of two distinct spatial configurations, leading to the existence of two enantiomers.

Enantiomers share many physical and chemical properties, such as melting point, boiling point, and solubility. However, they differ in their interaction with plane-polarized light. One enantiomer will rotate the plane of polarized light in a clockwise direction (designated as dextrorotatory or +), while its mirror image will rotate it in the counter-clockwise direction (designated as levorotatory or -). This property is known as optical activity.

In biological systems, enantiomers can exhibit drastically different biological activities. This is because biological molecules, such as enzymes and receptors, are themselves chiral and often interact stereoselectively with other chiral molecules. One enantiomer of a drug, for instance, might be therapeutically effective, while its enantiomer could be inactive or even toxic. A racemic mixture contains equal amounts of both enantiomers and is optically inactive. The separation of enantiomers, known as chiral resolution, is a crucial process in pharmaceuticals and other fields requiring pure enantiomers.