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Question #44643

Difficulty: 8/10 | 🟢 Free

The Question

Consider the following reaction sequence for 1-bromo-4-nitrobenzene ( $\textbf{P}$ ):

Step 1: $\textbf{P}$ is treated with $\ce{Sn / HCl}$ followed by aqueous $\ce{NaOH}$ workup to yield $\textbf{Q}$ . Step 2: $\textbf{Q}$ is reacted with 1 equivalent of $\ce{Na}$ metal in dry ether, followed by the addition of 1 equivalent of $\ce{CH_3Cl}$ to yield $\textbf{R}$ as the major product.

Which of the following represents the structure of $\textbf{R}$ ?

Options

A.
4-methylaniline
B.
N-methyl-4-bromoaniline
C.
4-bromo-N,N-dimethylaniline
D.
4,4'-dimethylazobenzene

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Exception_Exposure

Learn to identify edge cases and boundary exceptions that JEE examiners hide in math problems.

Concepts Behind This Question

Wurtz and Wurtz-Fittig Coupling|Reduction Selectivity (Sn/HCl vs LiAlH4)

Why This Question Is Tricky

Common Mistakes

This question tests the hierarchy of functional group reactivity and the limitations of the Wurtz-Fittig reaction.

The 'Hidden Variable' is the presence of active hydrogens generated mid-sequence.

Students algorithmically apply the Wurtz-Fittig coupling to aryl halides and alkyl halides with Na/ether.

However, the reduction of the nitro group to an amine introduces acidic protons.

These protons react with Na metal (or quench any organosodium intermediate), shifting the reaction from a radical/carbanion C-C coupling to an acid-base reaction followed by N-alkylation.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Haloalkanes and Haloarenes - Class 12
Concept	Wurtz and Wurtz-Fittig Coupling
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free