Absolute configuration意思

"Absolute configuration" is a term used in chemistry, particularly in the context of stereochemistry, to describe the specific three-dimensional arrangement of atoms in a molecule. It refers to the exact orientation of substituents around a chiral center, which is a carbon atom (or sometimes another atom) that is attached to four different groups.

The absolute configuration of a chiral molecule is defined by the direction in which each substituent points in space. This is important because it determines the molecule's unique properties, including its biological activity and reactivity.

The convention for describing the absolute configuration of a chiral molecule is known as the R/S system, which was introduced by the Swiss chemist, Vitaly Lexis, in 1913. In this system, the substituents around the chiral center are assigned priorities based on the Cahn-Ingold-Prelog priority rules, which take into account the atomic number of the atoms and the direction in which they are pointing. The highest priority substituent is chosen as the starting point, and the other substituents are assigned a clockwise (R) or counterclockwise (S) direction based on the direction in which they appear to rotate the plane of a hypothetical paper that is being rotated around the chiral center.

The R configuration stands for "rectus" (Latin for "right"), and the S configuration stands for "sinister" (Latin for "left"). This nomenclature is used to unambiguously describe the absolute configuration of a chiral molecule, which is important in the pharmaceutical and chemical industries, where the properties of a molecule can depend critically on its chirality.