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Question #44930

Difficulty: 8/10 | 🟢 Free

The Question

An organic compound \textbf{X} (3-methyl-4-nitrophenyl acetate) is treated with excess \ce{LiAlH4} in THF followed by aqueous workup to yield an aromatic compound \textbf{Y} and a volatile aliphatic alcohol. Compound \textbf{Y} is then subjected to the Hinsberg test using excess benzenesulfonyl chloride (\ce{PhSO2Cl}) in aqueous \ce{NaOH} at 298 K, yielding \textbf{W} as the major organic product. Which of the following statements correctly identifies the structure of \textbf{W} and its physical state in the alkaline reaction mixture?

Options

A.
\textbf{W} is $N$ -(4-hydroxy-2-methylphenyl)benzenesulfonamide and forms a clear soluble solution.
B.
\textbf{W} is 4-(benzenesulfonamido)-3-methylphenyl benzenesulfonate and forms a clear soluble solution due to N-H deprotonation.
C.
\textbf{W} is 4-(benzenesulfonamido)-3-methylphenyl benzenesulfonate and remains as an insoluble precipitate.
D.
\textbf{W} is $N,N$ -bis(benzenesulfonyl)-4-amino-3-methylphenol and remains as an insoluble precipitate.

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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

Reduction Selectivity (Sn/HCl vs LiAlH4)|Hinsberg Reagent Selectivity|Basicity-Solvation Competition

Why This Question Is Tricky

Common Mistakes

This question tests the 'Hinsberg solubility paradox', a critical exception in qualitative organic analysis.

Students typically memorize the rote rule that primary amines form alkali-soluble sulfonamides.

The trap introduces a hidden secondary nucleophilic site (a phenolic -OH generated via ester reduction) that undergoes O-sulfonylation.

The resulting N,O-bis(benzenesulfonyl) derivative, despite forming an anion in base, is so sterically bulky and hydrophobic that its sodium salt is insoluble in water.

This forces the student to evaluate physical organic principles (hydrophobic effect vs. ionic solvation) rather than relying on basic reaction heuristics.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Amines - Class 12
Concept	Reduction Selectivity (Sn/HCl vs LiAlH4)
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free