Question

Which of the following will be most stable diazoniumsalt RN²⁺X^- ?

• A. \(C_6H_5 \ N_2^+X_-\)
• B. \(CH_3CH_2\ N_2^+X^-\)
• C. \(C_6H_5\ CH_2\ N_2^+X^-\)
• D. \(CH_3\ N_2^+X^-\)

Answer 1

The Correct Option is A

Diazonium salts have the general formula RN_2^+X^-\). The stability of diazonium salts largely depends on the nature of the substituent group \(R\). Aromatic diazonium salts are generally more stable than aliphatic ones.

1. Aromatic Stabilization: The presence of an aromatic ring (e.g., benzene) enhances stability due to resonance stabilization. The lone pair on the nitrogen in the diazonium group can participate in resonance with the aromatic ring, spreading out the positive charge.
2. Analysis of Given Options:
   • \(C_6H_5 N_2^+X^-\): The phenyl group (C_6H_5\)) provides a resonance stabilization effect, making this diazonium salt the most stable among the options.
   • \(CH_3CH_2 N_2^+X^-\): An aliphatic group with no significant resonance stabilization, leading to less stability.
   • \(C_6H_5CH_2 N_2^+X^-\): Despite the presence of a benzene ring, the diazonium group is not directly attached to it, which fails to provide effective resonance stabilization.
   • \(CH_3 N_2^+X^-\): Another aliphatic group without resonance stabilization, thus less stable.
3. Conclusion: The option \(C_6H_5 N_2^+X^-\) is the most stable due to effective resonance stabilization from the aromatic phenyl group.