Identify the product (A) obtained in the following reaction
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Toluene (methylbenzene)
The reactant is p-toluenediazonium chloride (4-methylbenzenediazonium chloride). Mild reducing agents such as ethanol or hypophosphorous acid replace the diazonium group by hydrogen; ethanol is itself oxidised to ethanal:
\( \ce{CH3C6H4N2^+Cl^- + CH3CH2OH -> CH3C6H5 + N2 ^ + CH3CHO + HCl} \)
The methyl group is untouched, so the product (A) is toluene.
Why the other options are incorrect
Option (1) p-Cresol — Incorrect. A phenol forms when the diazonium salt is warmed with water (replacement by –OH), not with ethanol.
Option (2) p-Ethoxytoluene — Incorrect. Ethanol acts here as a mild reducing agent: it supplies the hydrogen that replaces –\( \ce{N2^+} \) and is itself oxidised to ethanal, so no ethoxy group is put on the ring.
Option (4) N-Ethyl-p-toluidine — Incorrect. This is an N-alkylated amine; the reaction removes nitrogen as \( \ce{N2} \), so no nitrogen is left on the ring.
NCERT (2026-27 edition):
Reactions Involving Displacement of Nitrogen – …
