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Question #44011

Difficulty: 8/10 | 🟢 Free

The Question

Consider the organic compound \textbf{X} with the structure \ce{OHC-C(CH3)2-CH2-CH2-C(=O)N(CH3)(OCH3)}. Compound \textbf{X} is subjected to the following reaction sequence to yield the major organic product \textbf{Z}:

\ce{HO-CH2-CH2-OH} (1 eq.), dry \ce{HCl} (cat.), benzene, $\Delta$ (Dean-Stark trap)
\ce{PhMgBr} (3.0 eq.), THF, $0^\circ\text{C}$
\ce{H3O^+}, $\Delta$

Which of the following statements correctly describes the behavior of compound \textbf{Z} in standard chemical tests?

Options

A.
\textbf{Z} gives a positive Tollens' test, a negative Fehling's test, and a negative iodoform test.
B.
\textbf{Z} gives a positive Tollens' test, a positive Fehling's test, and a negative iodoform test.
C.
\textbf{Z} gives a negative Tollens' test, a negative Fehling's test, and a positive iodoform test.
D.
\textbf{Z} gives a positive Tollens' test, a negative Fehling's test, and a positive iodoform test.

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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

Tollens vs. Fehling Specificity|Nucleophilic Acyl Substitution|Grignard Reaction Pathways

Why This Question Is Tricky

Common Mistakes

This problem tests three advanced concepts: 1) The chemoselectivity of acetal protection (aldehydes vs amides). 2) The 'hidden variable' of Weinreb amide reactivity, where a stable chelate prevents the thermodynamic over-addition of excess Grignard reagent. 3) The 'Chemical Exception' in oxidation tests where bulky $\alpha,\alpha$ -disubstituted aliphatic aldehydes (analogous to pivaldehyde) give a false negative with Fehling's solution due to steric hindrance, while still reacting with the less sterically demanding Tollens' reagent.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Aldehydes, Ketones, and Carboxylic Acids - Class 12
Concept	Tollens vs. Fehling Specificity
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free