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Question #43961

Difficulty: 8/10 | 🟢 Free

The Question

Consider the organic compound $\textbf{X}$ , $N$ -(4-acetylphenyl)methanesulfonamide. The objective is to chemoselectively reduce the carbonyl group to synthesize $N$ -(4-ethylphenyl)methanesulfonamide ( $\textbf{Y}$ ). Which of the following reagent systems is the most appropriate to achieve this transformation in high yield without degrading the sulfonamide functional group?

Options

A.
$NH_2NH_2$ , $KOH$ , ethylene glycol, $473\text{ K}$
B.
$Zn(Hg)$ , conc. $HCl$ , $373\text{ K}$
C.
(i) $HSCH_2CH_2SH$ , $BF_3\cdot OEt_2$ ; (ii) Raney $Ni$ , $EtOH$ , $\Delta$
D.
$HI$ , Red Phosphorus, $423\text{ K}$

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

Clemmensen vs. Wolff-Kishner|Hinsberg Reagent Selectivity

Why This Question Is Tricky

Common Mistakes

This question tests the student's awareness of functional group compatibility and chemoselectivity, specifically targeting the 'hidden' base- and acid-sensitivity of sulfonamides.

Students often blindly apply the Wolff-Kishner or Clemmensen reductions to any ketone.

The trap lies in failing to recognize that the harsh conditions required for these classical reductions (KOH at 200°C or refluxing conc.

HCl) are identical to the conditions used for the deprotection/cleavage of sulfonamides.

The Mozingo reduction serves as the necessary orthogonal, neutral alternative.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Aldehydes, Ketones, and Carboxylic Acids - Class 12
Concept	Clemmensen vs. Wolff-Kishner
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free