Which of the following cation would have greatest stability?

Options

A. `CH_(3)-S-CH_(2)^(+)`
B. `(CH_(3))_(2)NCH_(2)^(+)`
C. `CH_(3)-O-CH_(2)^(+)`
D. `F-CH_(2)^(+)`

Answer

B

Explanation

The lone pair of electrons on S is present in a 3p-orbital while those an N, O and F are present in a 2-p-orbital. Further, the carbon atom bearing the +ve charge has an empty 2p-orbital. Since effective resonance stabilization occurs between orbitals of similar sizes, therefore, least effective resonance will be between S and C atoms. Among N, O and F, since is least electronegative, therefore N, O and F, since N is least electronegative, therefore, most effective resonance will be between N and C and hence `(CH_(3))_(2)NCH_(2)^(+)` carbocations would be the most stable.