Question

Which of the following holds true with regard to the order of stability?

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

(a) Acetate ion (carboxylate ion) is more stable than phenoxide ion since the negative charge in acetate resides on more electronegative $O$ atoms in both its resonating structures whereas in phenoxide ion, it resides on one more electronegative $O$ and less electronegative $C$ atoms in its resonating structures.

(b) Both cations are resonating structures of each other. First one is more stable as it is $2^o$ and have more hyperonjugation.

(c) Cyclobutylmethylium cation is less stable due to ring strain so it rearranges to give cyclopentylium cation.

(d) Due to $\sigma$-bond resonance or dancing resonance, cyclopropylmethyl cation is more stable than cyclobutyl cation.