Question

In the presence of peroxide, styrene reacts with HBr to give X. When X is treated with magnesium in dry ether followed by CO$_2$ and hydrolysis, Y is formed. Treatment of Y with PCl$_5$, then with H$_2$/Pd-BaSO$_4$ gives Z. What is Z?

• A.

  

• B.

  

• C.

  

• D.

  

Hint:

Peroxide initiates anti-Markovnikov addition; follow Grignard to carboxylic acid, then Rosenmund reduction.

Answer 1

The Correct Option is A

Step 1: Peroxide effect — anti-Markovnikov addition of HBr → phenyl propyl bromide.
Step 2: Reaction with Mg forms Grignard reagent → addition of CO$_2$ → carboxylic acid.
Step 3: Treatment with PCl$_5$ forms acid chloride.
Step 4: Rosenmund reduction (H$_2$/Pd-BaSO$_4$) converts acid chloride to aldehyde.
Final product = phenyl propanal.