Enantiomerek

Enantiomerek, or enantiomers, are pairs of stereoisomers that are non-superimposable mirror images of one another. They occur when a molecule contains at least one stereogenic center, most often a carbon atom bonded to four different substituents, or other elements of chirality such as axial chirality. The two forms cannot be superimposed by any rotation in three-dimensional space. Because of this, enantiomers can behave very differently in chiral environments.

In achiral environments, enantiomers have identical physical properties, including boiling and melting points, density, and solubility. They differ in their interaction with plane-polarized light: each enantiomer rotates light by the same magnitude but in opposite directions. A pure enantiomer is optically active, whereas a 1:1 mixture of both enantiomers—the racemate—shows no net rotation.

Enantiomers often exhibit different biological and pharmacological activities because many biomolecules are chiral and differentiate between the two forms. This can lead to one enantiomer being beneficial while the other is less active or causes adverse effects. Consequently, enantioselective synthesis and enantioseparation are important in chemical synthesis, particularly in pharmaceuticals.

Methods to obtain or separate enantiomers include chiral resolution (for example by forming diastereomeric salts), catalytic enantioselective synthesis, and chiral chromatography or electrophoresis. The purity of an enantiomer is quantified by the enantiomeric excess (ee), defined as the absolute difference between the proportions of the two enantiomers. Stereochemical configurations at individual stereocenters are designated using the Cahn–Ingold–Prelog (CIP) priority rules (R and S).

Enantiomerek are a fundamental concept in chemistry and biochemistry, reflecting how molecular handedness influences interactions with light, receptors, and enzymes. They highlight the difference between symmetry and function in chiral molecules.