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4-Methylaniline is treated with acetic anhydride to give product A. Product A is then treated with bromine in acetic acid to give B. Finally, B is hydrolysed with water in the presence of acid to give product C. What is the structure of C?

1. Benzene ring bearing NHCOCH3, Br at ortho to NHCOCH3, and CH3 at para to NHCOCH3
2. Benzene ring bearing NH2, COCH3 at ortho, and CH3 at para
3. Benzene ring bearing COCH3, Br at ortho to COCH3, and CH3 at para
4. Benzene ring bearing NH2, Br at ortho to NH2, and CH3 at para to NH2

Correct answer: Benzene ring bearing NH2, Br at ortho to NH2, and CH3 at para to NH2

Solution

Step 1: 4-Methylaniline + Ac2O gives 4-methyl-acetanilide (A: ring with NHCOCH3 and CH3 para). Step 2: Bromination with Br2/AcOH gives ortho-bromo product (B: ring with NHCOCH3, Br ortho, CH3 para) because -NHCOCH3 directs ortho/para and -CH3 already occupies para. Step 3: Acid hydrolysis (H2O/H+) cleaves the acetamide to give the free amine C: ring with NH2, Br ortho, CH3 para.

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