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Question #44428

Difficulty: 8/10 | 🟢 Free

The Question

Compound $\textbf{P}$ is 5-hydroxy-2,2-dimethylhexanal. $\textbf{P}$ is subjected to two separate reaction sequences:

$\textbf{P}$ is treated with excess Tollens' reagent at 298 K, followed by careful acidification to yield the major organic product $\textbf{Q}$ .
$\textbf{P}$ is treated with excess $\ce{I2 / NaOH}$ at 298 K, followed by careful acidification to yield the major organic product $\textbf{R}$ .

Which of the following correctly identifies $\textbf{Q}$ and $\textbf{R}$ ?

Options

A.
$\textbf{Q}$ is 5-hydroxy-2,2-dimethylhexanoic acid; $\textbf{R}$ is 2,2-dimethylpentanedioic acid.
B.
$\textbf{Q}$ is 2,2-dimethyl-5-oxohexanoic acid; $\textbf{R}$ is 2,2-dimethylpentanedioic acid.
C.
$\textbf{Q}$ is 5-hydroxy-2,2-dimethylhexanoic acid; $\textbf{R}$ is 4,4-dimethyl-5-oxopentanoic acid.
D.
$\textbf{Q}$ is 5-hydroxy-2,2-dimethylhexanoic acid; $\textbf{R}$ is 2,2-dimethyl-5-oxohexanoic 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

Iodoform Reaction Requirements|Tollens vs. Fehling Specificity

Why This Question Is Tricky

Common Mistakes

This question tests 'Functional Group Interference' and the specific oxidizing capabilities of diagnostic reagents.

A common student trap is assuming that $\ce{I2 / NaOH}$ only acts as a test for methyl ketones or secondary alcohols, forgetting that hypohalites are strong enough to oxidize aldehydes to carboxylic acids (eliminating Option C).

Another trap is failing to recognize that the secondary alcohol is first oxidized to a methyl ketone before undergoing the iodoform cleavage (eliminating Option D), or incorrectly assuming Tollens' reagent is strong enough to oxidize secondary alcohols (eliminating Option B).

The absence of $\alpha$ -hydrogens adjacent to the aldehyde in $\textbf{P}$ prevents competing aldol or $\alpha$ -halogenation side reactions, ensuring a clean transformation.

Quick Facts About This Question

Question Information

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