Chiral Centres

Chirality

• A molecule is described as being chiral if has a non-superimposable mirror images.
• One way for a molecule to be chiral is through the presence of an asymmetric center (sometimes referred to as a chiral center), a tetrahedral center with four unique substituents.
• We use the R and S stereochemical identifiers to distinguish between the two chiral forms, called enantiomers.

• Enantiomers have the same physical properties (melting points, boiling points, etc.) but different chemical properties when they interact with other chiral molecules. This is especially common in biological systems which are full of chiral molecules.

• Different enantiomers of the same drug can have wildly different properties.
• It was found that the R isomer actually converts into the S isomer in the body.