Question

Which of the following is a major product obtained in the reaction of isobutylene with hydrogen bromide?

• A. tert-butyl bromide
• B. sec-butyl bromide
• C. n-butyl bromide
• D. iso-butyl bromide

Hint:

Markovnikov addition leads to formation of more stable carbocation intermediates.

Answer 1

The Correct Option is A

Step 1: Nature of isobutylene.
Isobutylene (2-methylpropene) is an unsymmetrical alkene that follows Markovnikov’s rule during addition reactions.

Step 2: Addition of HBr.
In the absence of peroxide, hydrogen bromide adds according to Markovnikov’s rule, forming the more stable tertiary carbocation intermediate.

Step 3: Product formation.
The bromide ion attacks the tertiary carbocation, resulting in the formation of tert-butyl bromide as the major product.

Step 4: Conclusion.
Thus, the major product formed is tert-butyl bromide.