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Question #44416

Difficulty: 8/10 | 🟢 Free

The Question

Consider the compound \textbf{X}, 5-hydroxyhexan-2-one. It is subjected to three different reducing conditions to yield major organic products \textbf{P}, \textbf{Q}, and \textbf{R}:

Reaction 1: \textbf{X} $\xrightarrow{Zn(Hg),\text{ conc. } HCl,\ \Delta}$ \textbf{P}

Reaction 2: \textbf{X} $\xrightarrow{NH_2NH_2,\ KOH,\ \text{ethylene glycol},\ \Delta}$ \textbf{Q}

Reaction 3: \textbf{X} $\xrightarrow{1.\ LiAlH_4,\ \text{dry ether} \quad 2.\ H_3O^+}$ \textbf{R}

Identify the major products \textbf{P}, \textbf{Q}, and \textbf{R}.

Options

A.
\textbf{P}: 2,5-dimethyltetrahydrofuran; \textbf{Q}: hexan-2-ol; \textbf{R}: hexane-2,5-diol
B.
\textbf{P}: 2-chlorohexane; \textbf{Q}: hexan-2-ol; \textbf{R}: hexane-2,5-diol
C.
\textbf{P}: hexan-2-ol; \textbf{Q}: hex-2-ene; \textbf{R}: hexane-2,5-diol
D.
\textbf{P}: 2,5-dimethyltetrahydrofuran; \textbf{Q}: 2,5-dimethyltetrahydrofuran; \textbf{R}: hexane-2,5-diol

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

Oxidation State Traps|Reduction Selectivity (Sn/HCl vs LiAlH4)|Clemmensen vs. Wolff-Kishner

Why This Question Is Tricky

Common Mistakes

This question tests the chemoselectivity and condition-dependent side reactions of standard carbonyl reductions.

Students often memorize Clemmensen ( $Zn(Hg)/HCl$ ) and Wolff-Kishner ( $NH_2NH_2/KOH$ ) as simple 'ketone to alkane' transformations, ignoring the solvent/pH conditions.

The 'Hidden Mechanism' is the acid-catalyzed intramolecular cyclization of the $\gamma$ -hydroxy ketone to a hemiacetal during the Clemmensen reduction.

Because the hemiacetal forms rapidly, the reduction acts on the oxocarbenium ion, leading to a cyclic ether rather than the expected open-chain alkane or alkyl chloride.

Conversely, the basic conditions of Wolff-Kishner preserve the secondary alcohol, demonstrating orthogonal chemoselectivity.

Quick Facts About This Question

Question Information

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