Question

Which of the following reaction is NOT correctly represented? 

• A. Methylbenzene + Br\(_2\) \(\xrightarrow{hv}\) Benzyl bromide
• B. Benzene diazonium chloride + Cu\(_2\)Br\(_2\)/HBr \(\to\) Bromobenzene
• C. Methylbenzene + Br\(_2\)/Fe (dark) \(\to\) Ortho- and para-bromotoluenes
• D. Methylbenzene + Br\(_2\) \(\xrightarrow{hv}\) Benzyl bromide

Hint:

For aromatic halogenation: - Use Lewis acids (Fe/FeCl\(_3\)) → ring substitution. - Use light (\(hv\)) → benzylic radical substitution. - Diazonium salts undergo Sandmeyer reactions to form aryl halides.

Answer 1

The Correct Option is D

Step 1: Recall reaction types. - Free radical halogenation occurs at the benzylic position under light (\(hv\)). - Electrophilic substitution occurs on the aromatic ring in the presence of Lewis acids (Fe/FeCl\(_3\)). - Sandmeyer reaction converts diazonium salts into aryl halides using Cu salts.
Step 2: Analyze each option. - (1) Correct: Radical bromination of toluene at benzylic position gives benzyl bromide. - (2) Correct: Sandmeyer reaction gives bromobenzene. - (3) Correct: Electrophilic substitution of toluene with Br\(_2\)/Fe gives ortho- and para-bromotoluenes. - (4) Incorrect: This is a repetition of (1), but shown as a separate option. The duplication makes it incorrectly represented in the given set.
Step 3: Conclusion. Thus, option (4) is NOT correctly represented.