JEE Main Chemistry question

In a reaction of aniline (A), a coloured product C was obtained: PhNH₂ —NaNO₂/HCl→ B (a diazonium salt) —*N,N*-dimethylaniline, cold→ C. The structure of C would be

(A)Ph–N=N–C₆H₄–N(CH₃)₂ (a *para*-coupled azo dye)Correct
(B)Ph–NH–NH–C₆H₄–N(CH₃)₂ (a hydrazo-linked structure)
(C)Ph–N=N–C₆H₄–N(CH₃)₂, coupled *ortho* instead of *para* to the dimethylamino group
(D)Ph–N(CH₃)–N=N–C₆H₅ (an isomeric triazene-type structure)

Answer: (A)

Solution

Diazonium-salt coupling with an activated aromatic ring forms a new azo (–N=N–) linkage, not a hydrazo (–NH–NH–) linkage; coupling occurs

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Question ID VK-140236