The major product of the following chemical reaction is :

Correct Answer:

Reaction Analysis:

The given reaction involves an unsymmetrical alkene, 3-methylbut-1-ene, reacting with hydrogen bromide ($\text{HBr}$) in the presence of benzoyl peroxide, $({\text{C}}_6{\text{H}}_5\text{CO}{)}_2{\text{O}}_2$.

Step-by-Step Explanation:

1. Peroxide Effect (Kharasch Effect):
When $\text{HBr}$ reacts with an unsymmetrical alkene in the presence of organic peroxides, the reaction proceeds via a free-radical mechanism rather than an electrophilic addition mechanism. This leads to anti-Markovnikov addition of $\text{HBr}$.

2. Free Radical Generation & Attack:
The benzoyl peroxide undergoes homolytic cleavage to generate phenyl free radicals, which react with $\text{HBr}$ to produce bromine free radicals (${\text{Br}}^{•}$).

3. Addition of Bromine Radical:
The bromine radical (${\text{Br}}^{•}$) attacks the double bond of 3-methylbut-1-ene [(CH₃)₂CH-CH=CH₂]. To form the more stable secondary free radical [(CH₃)₂CH-C^•H-CH₂Br] rather than a primary free radical, the bromine radical attaches preferentially to the terminal, less substituted carbon atom (C-1).

4. Hydrogen Abstraction:
The secondary radical [(CH₃)₂CH-C^•H-CH₂Br] abstracts a hydrogen atom from another molecule of $\text{HBr}$ to yield 1-bromo-3-methylbutane [(CH₃)₂CH-CH₂-CH₂Br] as the major product.

Thus, the major product formed in the given reaction is 1-bromo-3-methylbutane: