Question

Identify the major product of following reaction.
\(\text{Propene}\rightarrow _{\text{Peroxide}\,}^{\text{HBr}\,}\,?\)

• A. 1 - Bromopropane
• B. 2 - Bromopropane
• C. 3 - Bromopropene
• D. 2 - Bromopropan-1-ol

Hint:

With peroxide, HBr adds to propene by a free radical path against Markovnikov, giving the 1-bromo product.

Answer 1

The Correct Option is A

Step 1: Normal rule vs peroxide rule
Without peroxide, HBr adds by an ionic path and Br ends on the carbon with fewer hydrogens (Markovnikov), giving 2-bromopropane. With peroxide the path is a radical chain and the orientation reverses.

Step 2: Radical stability
Br radical attack at the terminal carbon creates a secondary carbon radical, which is more stable than the primary radical that would result from attack on the middle carbon.

Step 3: Product
Hydrogen is then picked up by the secondary radical carbon, so Br stays on the terminal carbon: $\text{CH}_3\text{CH}_2\text{CH}_2\text{Br}$.

Step 4: Answer
The major product is 1-bromopropane. Propene has no OH or allylic bromination step here, so options (C) and (D) are out.

Final Answer:
The peroxide effect gives the terminal bromide. This is option (A). \[ \boxed{\text{(A) }\text{1-Bromopropane}} \]