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
