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Question #45026

Difficulty: 8/10 | 🟢 Free

The Question

An equimolar mixture of anhydrous $\ce{ZnCl2}$ and $\ce{CuCl2}$ is dissolved in absolute ethanol ( $\ce{C2H5OH}$ ) at 298 K. To this homogeneous solution, one equivalent of benzylmagnesium chloride ( $\ce{C6H5CH2MgCl}$ ) is added dropwise. Given the standard reduction potentials ( $E^\circ_{\ce{Zn^{2+}/Zn}} = -0.76\text{ V}$ , $E^\circ_{\ce{Cu^{2+}/Cu}} = +0.34\text{ V}$ ), identify the major organic product formed.

Options

A.
$\ce{C6H5CH3}$
B.
$\ce{C6H5CH2CH2C6H5}$
C.
$\ce{(C6H5CH2)2Zn}$
D.
$\ce{C6H5CH2OC2H5}$

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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

Metal Activity Series Logic|Grignard Reagent Sensitivity|Solvent Effects on Reactivity

Why This Question Is Tricky

Common Mistakes

The problem tests the student's ability to prioritize reaction kinetics over thermodynamic redox potentials.

While the standard reduction potentials ( $E^\circ$ ) suggest a favorable redox displacement or oxidative coupling (forming bibenzyl via $\ce{Cu^{2+}}$ ), the presence of a protic solvent (ethanol) introduces a diffusion-controlled acid-base reaction.

Students often fall into the trap of focusing on the explicit metal salts and their activity series, overlooking the extreme sensitivity of Grignard reagents to protic environments, which instantly quenches the reagent to an alkane.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Redox Reactions - Class 11 Part 2
Concept	Metal Activity Series Logic
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free