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Question #44386

Difficulty: 8/10 | 🟢 Free

The Question

Consider the following reaction sequence:

$\ce{2-Nitrophenol ->[Br_2 (1 \text{ eq}), CS_2][273 \text{ K}] P (Major)}$ $\ce{P ->[\text{conc. } HNO_3, \text{ conc. } H_2SO_4][333 \text{ K}] Q (Major)}$ $\ce{Q ->[PCl_5][\Delta] R (Major)}$ $\ce{R ->[NaSCH_3 (1 \text{ eq})][\text{DMF, 298 K}] S (Major)}$

Identify the major product \textbf{S}.

Options

A.
\ce{5-bromo-2-(methylthio)-1,3-dinitrobenzene}
B.
\ce{2-chloro-5-(methylthio)-1,3-dinitrobenzene}
C.
\ce{4-bromo-1-(methylthio)-2,3-dinitrobenzene}
D.
\ce{4-(methylthio)-2,6-dinitrophenol}

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

EAS in Phenols|Phenol Acidity vs. Substituents|Nucleophilic Aromatic Substitution (SNAr)

Why This Question Is Tricky

Common Mistakes

This problem tests the competitive electronic effects in multi-substituted aromatic rings and the transition from EAS to SNAr reactivity.

The core trap lies in recognizing that while \ce{-OH} activates the ring for EAS (dominating over \ce{-NO2} and \ce{-Br} for regioselectivity), the accumulation of \ce{-NO2} groups transforms the ring's reactivity.

Students often fail to realize that highly electron-deficient phenols can be converted to aryl chlorides using \ce{PCl_5} (a reaction typical for carboxylic acids).

Furthermore, the final step tests regioselective SNAr, requiring the identification of the correct leaving group based on Meisenheimer intermediate stabilization, trapping students who might blindly replace the heavier halogen (\ce{-Br}) or fail to recognize its meta-deactivation.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Alcohols, Phenols, and Ethers - Class 12
Concept	EAS in Phenols
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free