Identify [A], [B] and [C], respectively in the following reaction sequence : [figure]
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Answer
(3) [figure]
Solution
NaNO2/HCl at 273–278 K converts a primary aromatic amine into the diazonium salt (diazotisation).
[A] = aniline:
C6H5NH2 + NaNO2 + 2HCl 273-278 K C6H5N2+Cl- + NaCl + 2H2O
Iodide ion replaces the diazonium group directly (no copper salt needed):
C6H5N2+Cl- + KI C6H5I + KCl + N2
[B] = iodobenzene
Fittig reaction: two aryl halide molecules couple with sodium in dry ether:
2C6H5I + 2Na Dry ether C6H5-C6H5 + 2NaI
[C] = biphenyl
Answer: (3)