Question

What will be formed when \(CH_{3}-CH=CH_{2}+HBr\) reacts in the presence of peroxide?

• A. \(CH_{3}-CH_{2}-CH_{2}-Br\) (n-propyl bromide)
• B. \(CH_{3}-CHBr-CH_{3}\) (isopropyl bromide)
• C. \(BrCH_{2}-CH=CH_{2}\) (allyl bromide)
• D. No reaction will occur.

Hint:

Remember: Without peroxide, \[ \boxed{\text{HBr follows Markovnikov's rule}.} \] With peroxide, \[ \boxed{\text{HBr follows Anti-Markovnikov's rule}.} \] The peroxide (Kharasch) effect is shown only by HBr and not by HCl or HI.

Answer 1

The Correct Option is A

In the presence of peroxide, HBr adds to propene via a free-radical mechanism following anti-Markovnikov's rule: the bromine radical adds preferentially to the less substituted terminal carbon. The product is 1-bromopropane ($CH_3CH_2CH_2Br$).