Enantiomers: The pair of stereoisomers that are non – superimposable mirror images with each other. A non-superimposable mirror image is a necessary condition for the chirality of the molecule. similarly, chirality is the necessary condition for the molecule to show enantiomerism.
Characteristics of Enantiomers:
- They have identical physical and chemiscal properties.
- But, they show different actibvity towards plane polarised light and optically active reagent.
- The possible stereo isomers is given by 2n where n is the no of chiral centre or chiral carbon in the molecules.
Diastereomers: The pair of stereoisomers that do not mirror images of each other are called diastereomers
Characteristics of Diastereomers :
- They have similar chemical properties but different physical properties. i.e melting, boiling point, refractive index, solubility, density etc.
- They may or may not be optically active.
- They can be separated from one another due to the different in their physical properties.
From the above figure, I and III, II and IV, I and IV, and II and IV are diastereomers.