Question

The major product of the following reaction is

• A.
• B.
• C.
• D.

Answer 1

The Correct Option is D

The given reaction involves the treatment of an unsaturated ester with 2 equivalents of HBr. This reaction will primarily follow the Markovnikov rule, which states that during the addition of HBr to an unsymmetrical alkene, the hydrogen atom attaches to the carbon that has more hydrogen atoms, and the bromine attaches to the carbon with fewer hydrogen atoms. 

1. In this case, the molecule consists of two vinyl groups (alkene groups) and a carbonyl (ester) group. The presence of the carbonyl group polarizes the adjacent double bond, making it electron-deficient and more reactive towards electrophiles like HBr.
2. The first equivalent of HBr will add across the double bond closer to the ester, following Markovnikov addition. This will result in the formation of a carbocation intermediate at the more substituted carbon.
3. The carbocation thus formed will be stabilized by the resonance effect from the carbonyl group.
4. The second equivalent of HBr will add to the remaining alkene group, also following Markovnikov's rule. This ensures that the H attaches to the less substituted carbon and Br to the more substituted carbon.

After the addition of both equivalents of HBr, the major product is a dibromide where both bromine atoms are attached to carbons adjacent to the original alkene positions.

The correct option is (D) :