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Question #44377

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The Question

An alkene $\textbf{X}$ is synthesized by the Wittig reaction of 1-methylcyclopentane-1-carbaldehyde with methylenetriphenylphosphorane. $\textbf{X}$ is then subjected to three distinct hydration protocols to yield major products $\textbf{P}$ , $\textbf{Q}$ , and $\textbf{R}$ :

$\textbf{Path A:}$ $\ce{H2O / H2SO4}$ (cat.), $\Delta \rightarrow \textbf{P}$

$\textbf{Path B:}$ (i) $\ce{Hg(OAc)2, H2O, THF}$ (ii) $\ce{NaBH4, NaOH} \rightarrow \textbf{Q}$

$\textbf{Path C:}$ (i) $\ce{BH3 \cdot THF}$ (ii) $\ce{H2O2, NaOH} \rightarrow \textbf{R}$

Identify the correct IUPAC names for the major products $\textbf{P}$ , $\textbf{Q}$ , and $\textbf{R}$ .

Options

A.
$\textbf{P}$ : 1,2-dimethylcyclohexan-1-ol ; $\textbf{Q}$ : 1-(1-methylcyclopentyl)ethan-1-ol ; $\textbf{R}$ : 2-(1-methylcyclopentyl)ethan-1-ol
B.
$\textbf{P}$ : 1-isopropylcyclopentan-1-ol ; $\textbf{Q}$ : 1-(1-methylcyclopentyl)ethan-1-ol ; $\textbf{R}$ : 2-(1-methylcyclopentyl)ethan-1-ol
C.
$\textbf{P}$ : 1,2-dimethylcyclohexan-1-ol ; $\textbf{Q}$ : 2-(1-methylcyclopentyl)ethan-1-ol ; $\textbf{R}$ : 1-(1-methylcyclopentyl)ethan-1-ol
D.
$\textbf{P}$ : 1,2-dimethylcyclohexan-1-ol ; $\textbf{Q}$ : 1,2-dimethylcyclohexan-1-ol ; $\textbf{R}$ : 2-(1-methylcyclopentyl)ethan-1-ol

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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

Oxymercuration-Demercuration Specificity|Hydroboration-Oxidation Regiochemistry

Why This Question Is Tricky

Common Mistakes

This problem tests the critical distinctions between three hydration methods.

The 'Hidden Variable' is the competition between a methyl shift and a 5-to-6 ring expansion during acid-catalyzed hydration.

Students often default to a simple methyl shift to form a tertiary carbocation, forgetting that expanding a cyclopentyl ring to a cyclohexyl ring relieves significant angle and torsional strain, making it the thermodynamically favored pathway.

Furthermore, it contrasts this rearrangement with OM-DM and HBO, which strictly forbid skeletal rearrangements due to their concerted/bridged transition states, testing the student's ability to apply regiochemical rules (Markovnikov vs Anti-Markovnikov) on complex branched substrates without falling for the rearrangement trap.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Alcohols, Phenols, and Ethers - Class 12
Concept	Oxymercuration-Demercuration Specificity
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free