Denantiomer

Denantiomer is not a standard term in chemistry. The non-superimposable mirror-image forms of a chiral molecule are normally called enantiomers. In many cases, "denantiomer" may appear as a misspelling or a misinterpretation in non-scientific writing. This article uses the conventional term enantiomer.

Enantiomers are a pair of stereoisomers that are non-superimposable mirror images. They have identical molecular formulas and, in achiral environments, indistinguishable physical properties. They differ in the direction they rotate plane-polarized light and in their interactions with other chiral systems, such as enzymes or receptors. Enantiomers are designated as dextrorotatory or levorotatory (often written as d- and l-) or as (+) and (−); their absolute configurations are assigned by Cahn–Ingold–Prelog rules as R or S for each stereogenic center.

Enantiomer pairs are related as mirror images; enantiomers are not diastereomers. A racemate is a 1:1 mixture of enantiomers that typically shows no net optical rotation. Separation and purification of enantiomers—chiral resolution or asymmetric synthesis—are important in chemistry and pharmacology because enantiomers can have different biological activities.

Examples and significance: lactic acid exists as two enantiomers, as does carvone, giving minty versus spearmint odors. In drugs, one enantiomer may be therapeutic while the other is inactive or harmful; thus enantiomeric purity is often critical.

Analysis and determination: polarimetry measures optical rotation, while chiral chromatography and circular dichroism assess enantiomeric purity and structure.