stereoselektiot

Stereoselection is a term used in chemistry to describe a reaction that preferentially forms one stereoisomer over other possible stereoisomers. This means that out of the multiple three-dimensional arrangements a molecule can take, the reaction is more likely to produce a specific one. This preference arises from the inherent stereochemistry of the reactants and the reaction mechanism itself.

Chirality, the property of a molecule being non-superimposable on its mirror image, is central to stereoselection. When a chiral molecule is formed, it can exist as different stereoisomers, often enantiomers (non-superimposable mirror images) or diastereomers (stereoisomers that are not mirror images). A stereoselective reaction will yield a higher proportion of one of these stereoisomers than would be expected by random chance.

The degree of stereoselection is often quantified by terms such as enantiomeric excess (ee) or diastereomeric excess (de). High stereoselection is crucial in many areas of chemistry, particularly in the synthesis of pharmaceuticals, where different stereoisomers can have vastly different biological activities, and sometimes one can be beneficial while another is harmful. Understanding and controlling stereoselection allows chemists to synthesize specific, desired stereoisomers with high purity.