Chemistry - STEREO ISOMERISM Question with Solution | TestHub
Assertion :- D-enantiomer rotate the plane-polarised light clockwise and L-enantiomer anticlockwise.
Reason :- D & L stereoisomers are enantiomers
Options:
Answer:
Solution:
Explanation: This question deals with the relationship between configuration (D/L system) and the direction of optical rotation.
Concept:
This question is based on optical activity, stereochemical nomenclature (D/L system).
Solution:
Statement-I:
D-enantiomer rotates plane-polarized light to the right and L-enantiomer to the left. (Incorrect)
The D/L notation is based on relative configuration with respect to glyceraldehyde, not on the direction
of optical rotation.
A D-compound can be either dextrorotatory (+) or levorotatory (−), and the same is true for L-compounds.
Hence, D does not necessarily mean right-rotating, and L does not necessarily mean left-rotating.
Statement-II: D & L stereoisomers are enantiomers. (Correct)
For a given compound, the D and L forms are non-superimposable mirror images of each other and
therefore are enantiomers.
Final Answer: option (D)