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Question #44355

Difficulty: 8/10 | 🟢 Free

The Question

Consider the compound 1-bromo-2-fluorobenzene. It is subjected to two distinct reaction conditions to yield major organic products $\textbf{P}$ and $\textbf{Q}$ :

Condition I: $\ce{NaNH2}$ (3 equivalents), $\ce{NH3 (l)}$ , $240\text{ K} \longrightarrow \textbf{P}$ Condition II: $\ce{NaOMe}$ (excess), DMSO, $373\text{ K} \longrightarrow \textbf{Q}$

Identify the major products $\textbf{P}$ and $\textbf{Q}$ .

Options

A.
$\textbf{P}$ = 3-fluoroaniline; $\textbf{Q}$ = 1-bromo-2-methoxybenzene
B.
$\textbf{P}$ = 2-fluoroaniline; $\textbf{Q}$ = 1-fluoro-2-methoxybenzene
C.
$\textbf{P}$ = 3-fluoroaniline; $\textbf{Q}$ = 1-fluoro-2-methoxybenzene
D.
$\textbf{P}$ = 2-fluoroaniline; $\textbf{Q}$ = 1-bromo-2-methoxybenzene

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

Nucleophilic Aromatic Substitution (SNAr)|Benzyne Intermediate (Elimination-Addition)

Why This Question Is Tricky

Common Mistakes

This question tests the chemoselectivity and regioselectivity competition between Benzyne and SNAr mechanisms.

Trap 1: Students often incorrectly apply SN1/SN2 leaving group trends (Br > F) to SNAr, leading them to displace Br in Condition II.

In SNAr, F is the superior leaving group.

Trap 2: Failing to analyze the regioselectivity of the benzyne intermediate.

Students often assume direct ipso-substitution (yielding 2-fluoroaniline), missing that the -I effect of Fluorine directs the nucleophile to the meta position to stabilize the resulting carbanion.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Haloalkanes and Haloarenes - Class 12
Concept	Nucleophilic Aromatic Substitution (SNAr)
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free