In 1811, Arago discovered that the “plane of polarization” of linearly polarized light was rotate when a beam of light propagated through quartz in a direction parallel to its optic axis. This property of quartz is called optical activity.
One of very important characteristic of sugars is their ability to rotate rays of polarized light. Carbohydrates contain several similarly substitute asymmetric carbon atoms and are therefore all optically active. This property is referred to as optical rotation and such compounds are said to be optically active.
A compound is optically active if its mirror image is not superimposable upon the original. In the application of this test, it must be realized that the atoms in a molecule are in constant motion with respect to each other.
The optical activity can be determined by optical rotation (OR), optical rotary dispersion (ORD) and circular dichroism (CD).
Optical activity of carbohydrates
