Study Set Content:
. However, if a single enantiomer is examined (all sample molecules being right-handed, or all being left-handed), the plane of polarization is rotated in either a (), and the analyzer must be turned an appropriate matching angle
clockwise (positive) or counter-clockwise (negative) direction
analyzer must be turned an appropriate matching angle, α, if full light intensity is to reach the
detector
One enantiomer will rotate polarized light in a clockwise direction, termed
dextrorotatory or (+),
and its mirror-image partner in a counter-clockwise manner, termed
levorotatory or (–).
• If equal quantities of each enantiomer are examined , using the same sample cell, then the magnitude of the rotations will be the same, with one being positive and the other
negative
To be absolutely certain whether an observed rotation is positive or negative it is often necessary to make a () using a different amount or concentration of the sample.
second measurement
Since it is not always possible to obtain or use samples of exactly the same size, the observed rotation is usually corrected to compensate for variations in sample quantity and cell length. Thus it is common practice to convert the observed rotation, αα, to a specific rotation, by the following formula
is the specific rotation
is the length in dm
is the concentration in g/ml
designates that the light used is the 589 line from a sodium lamp
Compounds that rotate the plane of polarized light are termed
optically active.
Each enantiomer of a stereoisomeric pair is optically active and has an equal but() specific rotation
opposite-in-sign
BIOT law
c
l
D
T
– a physical process where the components (solutes) of a sample mixture are separated as a result of their differential distribution between stationary and mobile phases.
Chromatography
