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Question #44634

Difficulty: 8/10 | 🟢 Free

The Question

Consider the following reaction sequence:

$\text{1-bromo-4-(chloromethyl)benzene} \xrightarrow[\text{dry acetone, } \Delta]{\text{NaI (excess)}} \text{Y}$

$\text{Y} \xrightarrow{\text{Mg (1 eq.), dry ether}} \text{Z}$

$\text{Z} \xrightarrow[\text{2. } H_3O^+]{\text{1. } CO_2} \text{W}$

Identify the major product W.

Options

A.
2-(4-bromophenyl)ethanoic acid
B.
4-(chloromethyl)benzoic acid
C.
2-(4-iodophenyl)ethanoic acid
D.
4-(iodomethyl)benzoic 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

Finkelstein and Swarts Exchange|Aryl Halide Resonance|Nucleophilic Aromatic Substitution (SNAr)

Why This Question Is Tricky

Common Mistakes

The core trap tests the student's ability to differentiate between the reactivity of alkyl/benzylic halides and aryl halides under $S_N2$ conditions (Finkelstein reaction).

Students often blindly apply the reagent to the best leaving group (Br over Cl) without considering the structural context.

The aryl $C-Br$ bond is unreactive due to resonance-induced partial double-bond character and the electron-rich $\pi$ -cloud repelling the nucleophile.

A secondary trap tests chemoselectivity in Grignard formation, where the weaker and more reactive benzylic $C-I$ bond reacts preferentially over the aryl $C-Br$ bond.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Haloalkanes and Haloarenes - Class 12
Concept	Finkelstein and Swarts Exchange
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free