Identify the major products P, Q and R in the following sequence of reactions:

Reaction Sequence Analysis

Step 1: Friedel-Crafts Alkylation

The benzene reacts with CH₃CH₂CH₂Cl (1-chloropropane) in the presence of anhydrous AlCl₃. This reaction involves the formation of a carbocation as an intermediate.

• The 1° propyl carbocation rearranges to form a more stable 2° isopropyl carbocation (CH(CH₃)₂⁺).
• The benzene ring undergoes electrophilic substitution with this isopropyl carbocation, resulting in isopropylbenzene (cumene) as the product P.

P = C₆H₅CH(CH₃)₂ (isopropylbenzene or cumene)

Step 2: Oxidation

Isopropylbenzene (cumene) is oxidized with O₂ to form cumene hydroperoxide.

This step follows the mechanism of autoxidation, where the benzene ring remains intact, and a peroxide group attaches to the isopropyl side chain.

Step 3: Acidic Hydrolysis

The cumene hydroperoxide undergoes hydrolysis in the presence of H₃O⁺/Δ (acid and heat), breaking down into:

• Phenol (C₆H₅OH), labeled as Q.
• Acetone (CH₃–CO–CH₃), labeled as R.

Final Products

• P = C₆H₅CH(CH₃)₂ (isopropylbenzene or cumene)
• Q = C₆H₅OH (phenol)
• R = CH₃–CO–CH₃ (acetone)

Correct Option: D

The given answer matches the reaction pathway described above.