Specific Rotation
A standard measure of the degree to which a compound is dextrorotary or levorotary is the quantity called the specific rotation . Dextrorotary compounds have a positive specific rotation, while levorotary compounds have negative. Two enantiomers have equal and opposite specific rotations.
The formula for specific rotation is:
where: = specific rotation
α = observed rotation
c = concentration of the solution of an enantiomer
l = length of the tube (Polarimeter tube) in decimeters
The degree of rotation of plane-polarized light depends on the number of chiral molecules that it encounters on its way through the tube of polarimeter (thus, the length of the tube and concentration of the enantiomer). In many cases, it also depends on the temperature and the wavelength of light that is employed.
Read more about this topic: Dextrorotation And Levorotation
Famous quotes containing the words specific and/or rotation:
“The more specific idea of evolution now reached is—a change from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity, accompanying the dissipation of motion and integration of matter.”
—Herbert Spencer (1820–1903)
“The lazy manage to keep up with the earth’s rotation just as well as the industrious.”
—Mason Cooley (b. 1927)