Dextrorotation and Levorotation

Dextrorotation And Levorotation

Dextrorotation and levorotation (also spelled laevorotation) refer, respectively, to the properties of rotating plane polarized light clockwise (for dextrorotation) or counterclockwise (for levorotation), seen by an observer whom the light is approaching. A compound with dextrorotation is called dextrorotatory or dextrorotary, while a compound with levorotation is called levorotatory or levorotary.

Compounds with these properties are said to have optical activity and consist of chiral molecules. If a chiral molecule is dextrorotary, its enantiomer will be levorotary, and vice-versa. In fact, the enantiomers will rotate polarized light the same number of degrees, but in opposite directions.

It is not possible to determine whether a given chiral molecule will be levorotatory or dextrorotatory directly from its configuration, except via detailed computer modeling. In particular, both "R" and "S" stereocenters have the ability to be dextrorotatory or laevorotatory.