COMEDK2021ChemistryAmines
Which of the following is most stable?
Options
- ACH ₂ ~N ₂⁺ X⁻
- BC ₆ H ₅ ~N ₂⁺ X⁻
- CCH ₃ CH ₂ ~N ₂⁺ X⁻
- DC ₆ H ₅ CH ₂ ~N ₂⁺ X⁻
Correct answer
B. C ₆ H ₅ ~N ₂⁺ X⁻
Step-by-step solution
Stability of diazonium salts ( R-N₂^+X^- ) depends on the stability of the carbocation formed after loss of N₂ . CH₂N₂^+X^- and CH₃CH₂N₂^+X^- : aliphatic resulting carbocations are highly unstable. These decompose rapidly. C₆H₅CH₂N₂^+X^- : benzyl carbocation is resonance stabilized, but still relatively reactive. C₆H₅N₂^+X^- : the diazonium group is directly attached to the aromatic ring. The lone pair on the nitrogen delocalizes into the ring the diazonium cation itself is resonance stabilized. This makes benzene