Considering the above reaction, X and Y respectively are:
(A)(see structures)AB
(B)(see structures)AB✓ Correct
(C)(see structures)AB
(D)(see structures)AB
Answer: (B)
Solution
Aniline treated with NaNO2 and HCl at 273–278K is diazotised, so X is benzenediazonium chloride; the low temperature is what keeps it from hydrolysing to phenol. A diazonium ion is a weak electrophile and attacks only strongly activated rings, and N,N-dimethylaniline offers such a ring. Coupling occurs at the position para to the dimethylamino group, the most activated free position. X is benzenediazonium chloride and Y is p-(N,N-dimethylamino)azobenzene.
JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Single correct option