In the cumene to phenol preparation in presence of air, the intermediate is

Solution

Chemistry ma’am · 4 steps

Air attacks the one tertiary benzylic hydrogen of cumene and turns that carbon into a C–OOH group.

1. Where air attacks. Cumene is isopropylbenzene, C₆H₅CH(CH₃)₂. Its weakest C–H bond is the single hydrogen on the carbon joined to the ring. That carbon is both tertiary and benzylic, so the radical formed there is well stabilised.
2. Oxygen goes in. O₂ from air reacts by a radical chain and inserts between that carbon and its hydrogen. The product is cumene hydroperoxide, C₆H₅C(CH₃)₂OOH. This is the intermediate the question asks about.

   C₆H₅CH(CH₃)₂ →(O₂, air) C₆H₅C(CH₃)₂OOH →(H₃O⁺) C₆H₅OH + (CH₃)₂CO

3. Acid step. Dilute acid protonates the –OOH group and water leaves. The phenyl group then migrates from carbon to oxygen. Hydrolysis of the rearranged species gives phenol, with acetone as the by-product.
4. So. The structure with a benzene ring on a carbon carrying two CH₃ groups and an O–OH group is cumene hydroperoxide. That is option (d).

The idea to keep. Cumene process: O₂ gives cumene hydroperoxide, then acid splits it into phenol and acetone. If an option cannot give acetone along with phenol, it is not on this route.

Answer from the NTA final answer key. Solution by PrepWiser.