Question

Which of the following carbocations is exepected to be most stable?

<!--td {border: 1px solid #cccccc;}br {mso-data-placement:same-cell;}--> NEET 2018

• A.
• B.
• C.
• D.

Answer 1

The correct option is D


$-N{O}_2$ group shows electron-withdrawing $(-R)$ effect. The carbocations directly attached to the nitro group are highly unstable. As we can see in option (b) and (d) are highly unstable.
In option (c) also after resonance the carbocation formed is directly attached to the nitro so, it is also unstable.

Option (a) the carbocation is at para position w.r.t nitro group and even after resonance the carbocation forms at ortho position only. Thus the most stable carbocations is shown in option (a).