In a reaction of aniline a coloured product C was obtained. [figure] The structure of C would be
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Answer
(2) [figure]
Solution
Step 1 (diazotisation): as per NCERT, aniline reacts with nitrous acid (NaNO2 + HCl) at 273–278 K to give benzenediazonium chloride (B):
C6H5NH2 + NaNO2 + 2HCl C6H5N2+Cl- + NaCl + 2H2O
Step 2 (coupling): the diazonium ion is a weak electrophile and attacks the para position of the strongly activated ring of N,N-dimethylaniline in the cold:
C6H5N2+Cl- + C6H5N(CH3)2 C6H5-N=N-C6H4-N(CH3)2 + HCl
C is p-(N,N-dimethylamino)azobenzene, a yellow azo dye; the -N=N- group joins the two rings, and the -N(CH3)2 group stays para to it.
Answer: (2)