Question

Which of the following forms unstable diazonium ion when treated with $NaN{O}_2$ in aqueous $HCl$?

• A. p-nitrotoluene
• B. ethylamine
• C. N,N-dimethyl aniline
• D. All of the above

Answer 1

Answer: (B)

ethylamine

Aromatic diazonium salts are stable if kept cold $(0-5^{o}C)$ and in solution, but they often decompose violently when isolated. Their stability (compared to alkane diazonium salts) is due in part to resonance stabilization of the diazonium ion and in part to the very high energy of the aryl cation that would result from the loss of $N_2$(g).
Therefore except ethylamine all other given compounds forms stable diazonium ion when treated with $NaN{O}_2$ in aqueous $HCl$.
Hence, the correct option is B.