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Question #44031

Difficulty: 8/10 | 🟢 Free

The Question

Aniline is treated with $\ce{NaNO2 / HCl}$ at $273\text{ K}$ to yield compound $\textbf{P}$ . Compound $\textbf{P}$ is then reacted with $m$ -aminophenol under two distinct conditions:\n(i) In an aqueous buffer at $\text{pH} = 9.5$ to yield $\textbf{X}$ as the major product.\n(ii) In an aqueous buffer at $\text{pH} = 4.5$ to yield $\textbf{Y}$ as the major product.\nIdentify the correct IUPAC names for $\textbf{X}$ and $\textbf{Y}$ .

Options

A.
$\textbf{X}$ : 3-amino-4-(phenyldiazenyl)phenol, $\textbf{Y}$ : 5-amino-2-(phenyldiazenyl)phenol
B.
$\textbf{X}$ : 5-amino-2-(phenyldiazenyl)phenol, $\textbf{Y}$ : 3-amino-4-(phenyldiazenyl)phenol
C.
$\textbf{X}$ : 3-amino-4-(phenyldiazenyl)phenol, $\textbf{Y}$ : 3-amino-4-(phenyldiazenyl)phenol
D.
$\textbf{X}$ : 5-amino-2-(phenyldiazenyl)phenol, $\textbf{Y}$ : 5-amino-2-(phenyldiazenyl)phenol

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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

Aniline Resonance Pitfalls|Diazotization Temperature Sensitivity|Coupling Reactivity

Why This Question Is Tricky

Common Mistakes

This question tests the pH-dependent regioselectivity in electrophilic aromatic substitution (diazo coupling).

Students often memorize that $-NH_2$ and $-OH$ are activating groups but fail to account for the 'Hidden Variable' of pH.

At high pH, phenol deprotonates to phenoxide ( $-O^-$ ), which outcompetes $-NH_2$ as an activating group.

At weakly acidic pH, both groups are neutral (the reactive species is the free amine), and $-NH_2$ outcompetes $-OH$ due to nitrogen's lower electronegativity and superior $+M$ effect.

The trap lies in assuming a static hierarchy of activating groups regardless of the reaction medium.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Amines - Class 12
Concept	Aniline Resonance Pitfalls
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free