Question

Indicate more stable carbocation and explain :

• A. (II) is more stable, due to the + I effect of ${OCH}_3$.
• B. (I) is more stable, due to the + I effect of ${OCH}_3$.
• C. (II) is more stable, due to the + M effect of ${OCH}_3$.
• D. (I) is more stable, due to the + M effect of ${OCH}_3$.

Answer 1

The correct option is D (I) is more stable, due to the + M effect of ${OCH}_3$.

The carbocation $I$ is more stable as the positive charged carbon of ring is directly associated with $OC{H}_3$. The $+ve$ charge and lone pairs of $O$ are in resonance and $OC{H}_3$ has an electron releasing effect $+M$ effect which stabilize the charge on ring. But in carbocation $II$ the positive charge is not affected directly by $OC{H}_3$ but is just in conjugation with $\pi$ bonds of ring.