Question

The correct order of stability for the following species is:

• A. $\left(II\right)>\left(IV\right)>\left(I\right)>\left(III\right)$
• B. $\left(I\right)>\left(II\right)>\left(III\right)>\left(IV\right)$
• C. $\left(II\right)>\left(I\right)>\left(IV\right)>\left(III\right)$
• D. $\left(I\right)>\left(III\right)>\left(II\right)>\left(IV\right)$

Answer 1

The correct option is D $\left(I\right)>\left(III\right)>\left(II\right)>\left(IV\right)$

(I) It is a secondary carbocation stabilized by resonance. Also, it is the most stable carbocation among the four.

(II) It is a simple secondary carbocation.

(III) It is a primary carbocation stabilized by resonance.

(IV) It is a primary carbocation.

We know that the stability of carbocation follows the order
$3^o>2^o>1^o$. However, resonace stabilized primary carbocation is more stable than secondary carbocation.