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JEE Main 2025 Jan 28 Shift 2, Chemistry Q12: Aromatic Hydrocarbons: Benzene

JEE Main2025Jan 28, Shift 2Chemistry
Q.

The total number of compounds from below when treated with hot giving benzoic acid is :

  1. A

  2. B

  3. C

  4. D

Solution

Hot oxidises an alkyl side chain attached to a benzene ring to a group, provided there is at least one benzylic (alpha) C-H bond available. Side chains in which the benzylic carbon has no hydrogen (tert-alkyl or hydroxyl-bearing quaternary benzylic) are not oxidised, and a phenyl-phenyl bond (biphenyl) has no alkyl group at all.

Going through the seven structures:

Toluene, ethylbenzene, cumene and isobutylbenzene all carry benzylic hydrogens and give benzoic acid.

5th one also has benzylic H and gives benzoic acid.

tert-Butylbenzene and 2-phenyl-2-propanol have no benzylic hydrogen; biphenyl has no alkyl chain. These three do not give benzoic acid.

Number of compounds giving benzoic acid .

Concept behind this question

Aromatic Hydrocarbons: Benzene Notes, formulas and examples →

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