Chiraalinen

Chiraalinen is the Finnish term for chirality, a property of asymmetry where an object is not superimposable on its mirror image. In chemistry and related sciences, chiraalinen describes molecules or structures that lack an internal plane of symmetry and often contain stereogenic elements.

A common source of chirality in chemistry is a stereogenic center, typically a tetrahedral carbon bearing four different substituents. The non-superimposable mirror images of such a molecule are enantiomers. Enantiomers have identical physical properties in achiral environments but rotate plane-polarized light in opposite directions and can interact very differently with chiral surroundings, such as biological receptors or enzymes. A mixture with equal amounts of enantiomers is called racemic.

Chirality has implications beyond individual stereocenters. Axial chirality (as seen in certain biaryl compounds), planar chirality, and helical chirality arise from other types of spatial arrangement that are non-superimposable on their mirrors. In practice, many chemical processes seek enantiomerically enriched products through enantioselective synthesis, chiral catalysts, or resolution techniques such as separating diastereomeric salts or using chiral chromatography.

In biology, chirality is a fundamental feature of life. Biological systems preferentially use one hand of chiral building blocks, leading to homochirality, such as left-handed amino acids and right-handed sugars, which influences biomolecular recognition and function.

Historical note: the concept originated with Louis Pasteur’s separation of enantiomers of tartaric acid in the 19th century, laying the foundation for modern stereochemistry.