Optical isomerism

Two molecules or groups are optical isomers if their structures differ only by their geometry (which gives rise to different optical activities and perhaps physical properties).

The most common example is when there are asymmetric carbons in different configurations in the two molecules: cis and trans configurations around a double bond etc.

History of science Optical isomerism was studied by Pasteur, who separated the levorotatory and dextrorotatory forms of sodium ammonium tartrate (1848). Stereochemistry was founded on the work of Le Bel and van't Hoff (1875), who related the properties of the optical isomerism of certain compounds to the tetrahedral structure of carbon and the presence of asymmetric carbons.