Racemic mixture

A mixture containing equal amounts of two enantiomers. Their opposite optical rotations cancel, so the mixture has no net optical rotation under the same conditions.

Enantiomer: One of a pair of stereoisomers that are nonsuperimposable mirror images. A racemate contains equal amounts of this mirror-image pair.
Chirality (chemistry): The property of an object or molecule that makes it nonsuperimposable on its mirror image. Chirality allows molecules to occur as distinct mirror-image forms.
Racemic synthesis: A chemical synthesis that produces equal amounts of two enantiomers. It directly yields a racemic mixture when no enantiomer-selective process intervenes.
Chiral drug: A pharmaceutical whose molecules exist as nonsuperimposable mirror-image forms. A racemic drug supplies both forms, which can behave differently in biological systems.
Optical activity: The ability of a substance to rotate the plane of polarized light. Each enantiomer rotates polarized light in an opposite direction.
Stereoisomerism: Isomerism in which compounds have the same connectivity but different spatial arrangements of atoms. Enantiomers are stereoisomers whose spatial arrangements are mirror-related.
Asymmetric synthesis: A synthesis designed to produce one enantiomer preferentially over its mirror image. It avoids or reduces the equal-enantiomer outcome characteristic of a racemate.
Stereoselectivity: The preferential formation or reaction of one stereoisomer over another. Biological targets and chemical reactions can distinguish enantiomers despite a racemate's optical inactivity.
Specific rotation: Optical rotation normalized for path length, concentration, and measurement conditions. Equal enantiomer amounts cancel when their specific rotations have equal magnitude.
Stereocenter: An atom at which exchanging two attached groups produces a stereoisomer. A stereocenter often gives a molecule distinct enantiomeric forms.

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