Question

If there is no rotation of plane polarised light by a compound in a specific solvent, though to be chiral, it may mean that

• A. the compound is certainly a chiral
• B. the compound is certainly meso
• C. there is no compound in the solvent
• D. the compound may be a racemic mixture

Answer 1

Answer: (D)

The compound may be a racemic mixture because an optically active compound rotates plane polarized light. But due to some external compensation (heat, light, catalyst, solvent etc), the optically active compound loss their optical activity. The compound then exists as racemic mixture i. e., both d and l form are present in solution due to some intramolecular rearrangement. So, there is no rotation of plane polarised light and compound does not have an asymmetric centre and when it again forms the symmetric centre both d-and l forms are obtained in equal.