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Question #44481

Difficulty: 8/10 | 🟢 Free

The Question

Consider the following reaction sequence: $\ce{1-Bromo-4-phenylbutane} \xrightarrow[\text{dry ether}]{\ce{Mg}} \textbf{P} \xrightarrow[\text{2. } \ce{H3O+}]{\text{1. } \ce{AlCl3} \text{ (anhydrous, 1 eq)}} \textbf{Q}$ Which of the following represents the major organic product \textbf{Q}?

Options

A.
1,2,3,4-Tetrahydronaphthalene
B.
Butylbenzene
C.
1-Chloro-4-phenylbutane
D.
1,8-Diphenyloctane

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Mechanism_Trap

Don't get tricked by the process! Learn the mechanical traps used in competitive exam questions.

Concepts Behind This Question

Friedel-Crafts Alkylation Limitations|Grignard Reagent Sensitivity|Electrophile vs Nucleophile

Why This Question Is Tricky

Common Mistakes

This question tests the 'Chemical Exception' of functional group compatibility and polarity inversion (Umpolung).

Students are heavily conditioned to associate \ce{AlCl3} with Friedel-Crafts alkylation and often blindly apply it, ignoring that the substrate has been converted into a Grignard reagent.

The hidden mechanism is the transmetallation between the Grignard reagent and the Lewis acid.

This interaction quenches the extreme nucleophilicity of the Grignard but maintains the $C^{\delta-}$ polarity, fundamentally prohibiting the electrophilic aromatic substitution pathway required to form the cyclic product.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Hydrocarbons - Class 11 Part 2
Concept	Friedel-Crafts Alkylation Limitations
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free