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Question #44356

Difficulty: 8/10 | 🟢 Free

The Question

An organic compound \textbf{X} (3-fluoro-4-nitroaniline, 1.0 mol1.0 \text{ mol}) is subjected to the following sequential one-pot reaction:\n\n\textbf{Step 1:} Treated with Phenol (1.0 mol1.0 \text{ mol}) and \ce{NaOH} (3.0 mol3.0 \text{ mol}) in DMSO at 100∘C100^\circ\text{C}.\n\textbf{Step 2:} The resulting mixture is cooled to 0−5∘C0-5^\circ\text{C}, followed by the addition of \ce{NaNO2} (1.0 mol1.0 \text{ mol}) and \ce{HCl} (3.0 mol3.0 \text{ mol}).\n\nAssuming complete conversion in Step 1, what is the major organic product isolated at the end of Step 2?

Options

  • A.

    3-phenoxy-4-nitrobenzenediazonium chloride

  • B.

    1,3-bis(3-phenoxy-4-nitrophenyl)triazene

  • C.

    4-[(3-phenoxy-4-nitrophenyl)diazenyl]phenol

  • D.

    3-phenoxy-4-nitrophenol

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

Nucleophilic Aromatic Substitution (SNAr)|Azo Coupling Regioselectivity|Diazotization Temperature Sensitivity

Why This Question Is Tricky

Common Mistakes

This problem tests the student's ability to track limiting reagents across a multi-step synthesis and understand the mechanistic pH-dependence of diazotization.

The 'Hidden Variable' is the residual strong base from the SNAr step.

Students typically memorize '\ce{NaNO2} + \ce{HCl} -> Diazonium salt' without considering the stoichiometric requirement of excess acid to maintain an acidic pH.

If the pH is neutral or mildly basic, the free amine acts as a nucleophile, leading to premature N-coupling (diazoamino formation) rather than the stable diazonium chloride.

Quick Facts About This Question

Question Information

SubjectChemistry
ChapterHaloalkanes and Haloarenes - Class 12
ConceptNucleophilic Aromatic Substitution (SNAr)
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree