Stereokeskus

Stereokeskus is a term that refers to a central or focal point of stereochemistry within a molecule. It is a concept used in organic chemistry to describe an atom or group of atoms where stereoisomers can arise. This typically occurs at chiral centers, which are atoms, most commonly carbon, bonded to four different groups. The arrangement of these groups around the stereocenter determines the molecule's three-dimensional structure.

When a stereocenter is present, the molecule can exist as different stereoisomers, such as enantiomers or diastereomers. Enantiomers are stereoisomers that are non-superimposable mirror images of each other. Diastereomers are stereoisomers that are not mirror images. The stereochemistry at the stereocenter dictates the specific spatial orientation of the substituents.

Understanding stereocenters is crucial for predicting and explaining the physical and chemical properties of molecules, as stereoisomers can exhibit significantly different biological activities and reactivity. For example, in pharmaceuticals, one stereoisomer might be therapeutic while another is inactive or even harmful. The identification and characterization of stereocenters are fundamental aspects of organic synthesis and molecular analysis.