Question

The specific rotation of the compound (A) is $+X^o$.

Which of the following statement is/are true?

• A. Specific rotation of achiral diastereomer of A is zero
• B. Specific rotation of chiral diastereomer of A is $-X^o$
• C. Specific rotation of achiral structural isomers are zero
• D. Specific rotation of chiral structural isomer of A is $-X^o$

Answer 1

Answer: (A), (C)

Specific rotation of achiral structural isomers are zero

For a compound to show optical activity, it should have chirality.
Achiral molecules does not optical rotation.
Hence, statements (a) and (c) are correct.

Chiral diastereomer of (A) can have different value of specific rotation and it has to be determined experimentally.

Similary, chiral structural isomer of (A) can have different value of specific rotation and it has to be determined experimentally.

Only enantimeric pair will have same extent of specific rotation at opposite directions.