Question

Which of the following two carbonium ions is more stable?

• A. (a) - (II), (b) - (II)
• B. (a) - (I), (b) - (I)
• C. (a) - (I), (b) - (II)
• D. (a) - (II), (b) - (I)

Answer 1

The correct option is A (a) - (II), (b) - (II)

(a) With increase in the size of bridged ring system, the stability of the bridgehead carbocation increases. Therefore, structure (II) is more stable than (I).

(b) Due to the donation of lone pair of electrons of $N$ atom to the $p$-orbital of the carbon atom forming the cation, the stability of structure (II) is more than (I).