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Question #44350

Difficulty: 8/10 | 🟢 Free

The Question

Consider the following reaction sequence starting with 1-chloro-2-methoxybenzene (Compound \textbf{A}):

\textbf{A} $\xrightarrow{\ce{KNH2}, \text{ liq. } \ce{NH3}, 233 \text{ K}}$ \textbf{B} (Major Product)
\textbf{B} $\xrightarrow[\text{2. } \ce{CuCN}, \ce{KCN}, \Delta]{\text{1. } \ce{NaNO2}, \ce{HCl}, 273 \text{ K}}$ \textbf{C}
\textbf{C} $\xrightarrow[\text{2. } \ce{H3O+}]{\text{1. } \ce{CH3MgBr} \text{ (excess), dry ether}}$ \textbf{D}
\textbf{D} $\xrightarrow[\text{2. } \ce{H3O+}]{\text{1. } \ce{I2}, \ce{NaOH}, \Delta}$ \textbf{E} (Major Product) + $\ce{CHI3}$

Identify the final product \textbf{E}.

Options

A.
3-Methoxybenzoic acid
B.
2-Methoxybenzoic acid
C.
4-Methoxybenzoic acid
D.
3-Hydroxybenzoic acid

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

Electrophilic Substitution Activation/Deactivation|Benzyne Intermediate (Elimination-Addition)

Why This Question Is Tricky

Common Mistakes

This question tests the 'Benzyne Regiochemistry Trap'.

Students often assume that haloarenes undergoing substitution will either follow direct $S_NAr$ (yielding the ortho product) or be governed by standard Electrophilic Aromatic Substitution (EAS) directing effects (where -OMe is an ortho/para director).

The hidden mechanism is the Elimination-Addition pathway via a benzyne intermediate.

The regioselectivity of nucleophilic attack on benzyne is dictated entirely by the inductive effect (-I) of the substituent stabilizing the incipient carbanion, completely ignoring resonance (+M) effects since the carbanion is in an $sp^2$ orbital orthogonal to the pi system.

Failing to recognize the -I stabilization of the C2 carbanion leads to incorrect regiochemical predictions.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Haloalkanes and Haloarenes - Class 12
Concept	Electrophilic Substitution Activation/Deactivation
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free