Haloalkanes And Haloarenes Ques 35
35. Which of the following biphenyls is optically active?
[2016]
(a)
(b)
(c)
(d)
Show Answer
Answer:
Correct Answer: 35.(b)
Solution:
- (b) In option (a), there is no chiral carbon.
In option (c), there exist a center of symmetry.
In option (d), there exist a plane of symmetry.
In option (d), both the rings are not in the same plane and the rotation is restricted around the single bond.
Restricted rotation
Biphenyl compounds are devoid of individual chiral carbon atoms, but $o$-substituted biphenyl show optical isomerism. This is due to the fact that, both the rings are not in the same plane because of steric hindrance of the groups present in $o$ position. Also, these groups restrict the rotation around the single bond and hence they must exist in two non-super imposable mirror images of each other.
BETA
