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Question #44488

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The Question

Aniline is treated with a nitrating mixture (conc. \ce{HNO3} and conc. \ce{H2SO4}) at $288\text{ K}$ to yield three mononitrated products $P$ , $Q$ , and $R$ in $51\%$ , $47\%$ , and $2\%$ yields, respectively. Product $P$ is isolated, diazotized at $273\text{ K}$ , and treated with \ce{CuCN/KCN} followed by complete acidic hydrolysis to yield compound $W$ . Products $Q$ and $R$ are subjected to the identical sequence of reactions to yield compounds $T$ and $V$ , respectively. Which of the following represents the correct decreasing order of acidic strength ( $K_a$ ) of the compounds $W$ , $T$ , and $V$ in aqueous medium?

Options

A.
$V > W > T$
B.
$V > T > W$
C.
$W > V > T$
D.
$T > W > V$

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

Electrophilic Substitution Orientation|Ortho-Effect in Anilines|Acidity and Basicity (pKa/pKb)

Why This Question Is Tricky

Common Mistakes

This question tests two major chemical exceptions/traps.

First, students often assume the \ce{-NH2} group is purely o/p directing, overlooking its protonation to the meta-directing \ce{-NH3+} ion in strongly acidic nitrating mixtures, which is required to correctly identify $P$ , $Q$ , and $R$ .

Second, it tests the 'Ortho Effect' in benzoic acids.

Students relying solely on standard electronic effects ( $-M$ , $-I$ ) might incorrectly assume the para isomer ( $W$ ) is the most acidic.

The hidden variable is the steric inhibition of resonance in the ortho isomer ( $V$ ), which prevents the electron-donating resonance of the benzene ring from destabilizing the carboxylate anion, making $V$ the strongest acid.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Hydrocarbons - Class 11 Part 2
Concept	Electrophilic Substitution Orientation
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free