ExamsMy practice
Major product of the following reaction is - [figure]
- [figure]
- [figure]
- [figure]
- [figure]
Answer
(4) [figure]
Solution
Electrophilic addition (Markovnikov): D adds to the ring carbon without CH3, so the more stable 3° carbocation forms on the carbon bearing CH3; Cl then attacks it.
[figure]
Hence Cl and CH3 end up on the same carbon, and D on the next carbon.
Since the 3° carbocation is planar, Cl can attack it from either face, so the Markovnikov product forms as a cis/trans pair (each as a (±) mixture).
(A), (B): Cl on the carbon without CH3 (anti-Markovnikov), so these are not formed.
(C): Markovnikov product with D and Cl on the same face; it forms only in a smaller amount, because the face on the side of D is the more crowded one.
(D): Markovnikov product with D and Cl on opposite faces ( Cl attacks from the side away from D, i.e. anti addition), so (D) is the major product.
Answer: (4)