Which statement correctly compares m-CH3O-C6H4-CH2+ and p-CH3O-C6H4-CH2+?

the para isomer is more stable, because the methoxy lone pair can delocalise the charge onto oxygen only from the para (or ortho) position

the two are equally stable because OCH3 is the same group

the meta isomer is more stable, because the methoxy group donates by +M from the meta position

the meta isomer is more stable because the -I effect of oxygen is smaller there

the para isomer is more stable, because the methoxy lone pair can delocalise the charge onto oxygen only from the para (or ortho) position

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JEE Advanced levelSingle correct optionDifficulty 3 of 3g3039

Which statement correctly compares $m - CH X_{3} O - C X_{6} H X_{4} - CH X_{2} X^{+}$ and $p - CH X_{3} O - C X_{6} H X_{4} - CH X_{2} X^{+}$ ?

Athe two are equally stable because $OCH X_{3}$ is the same group
Bthe meta isomer is more stable, because the methoxy group donates by $+ M$ from the meta position
Cthe meta isomer is more stable because the $- I$ effect of oxygen is smaller there
Dthe para isomer is more stable, because the methoxy lone pair can delocalise the charge onto oxygen only from the para (or ortho) position

Answer: D

Positive charge is placed on the ortho and para ring carbons by resonance of the benzyl cation. A para-OCH3 can then donate a lone pair to give an oxocarbenium structure. At meta there is no such structure, and only the electron-withdrawing

- I

effect operates, so the para isomer is much more stable.

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Which statement correctly compares m-CHX3​O−CX6​HX4​−CHX2​X+ and p-CHX3​O−CX6​HX4​−CHX2​X+?

Answer: D

More questions on Carbocations: formation, stability, rearrangements

Which statement correctly compares $m - CH X_{3} O - C X_{6} H X_{4} - CH X_{2} X^{+}$ and $p - CH X_{3} O - C X_{6} H X_{4} - CH X_{2} X^{+}$ ?