If the specific rotation of Compound X is (-) 123.8º, what would be the observed
rotation of its enantiomer, Compound Y, assuming the concentration and cell path length
is the same?
b. If a racemic mixture of Compound X and Compound Y were analyzed, what would be
the observed rotation?
c. What would be the specific rotation of Compound Z, a diastereomer of Compound X
and Y?
a. +123.8
b. 0
c. http://en.wikipedia.org/wiki/Diastereomer
After reading the link for part c,i still don't understand it
would it be that Z is -123.8 since X is -123.8 and Y is +123.8?
To answer these questions, the concept of optical rotation and enantiomers needs to be understood.
Optical rotation is the rotation of the plane of polarized light when it passes through a substance. It is observed for chiral compounds, which have non-superimposable mirror image structures called enantiomers.
a. To calculate the observed rotation of the enantiomer Compound Y given the specific rotation of Compound X, you need to recognize that enantiomers have equal and opposite specific rotations. Therefore, the observed rotation for Compound Y would be (+) 123.8º.
b. When a racemic mixture is analyzed, it contains equal amounts of Compound X and Compound Y. The specific rotations of enantiomers cancel each other out, resulting in a net observed rotation of 0º. Therefore, the observed rotation of the racemic mixture would be 0º.
c. Diastereomers are stereoisomers that are not enantiomers. They have different specific rotations. Since Compound Z is a diastereomer of Compound X and Y, its specific rotation would not be the same as either X or Y. The specific rotation of Compound Z would need to be determined experimentally or calculated based on its molecular structure and its interaction with polarized light.