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

Question

Which of the following carbocations is expected to be most stable ? 1. cyclohexadienyl cation with NO ₂ at top carbon, Y and H on the sp ³ carbon, positive charge adjacent (picture) 2. cyclohexadienyl cation with NO ₂ at top carbon, H and Y on the sp ³ carbon, positive charge adjacent (picture) 3. cyclohexadienyl cation with positive charge on the carbon bearing NO ₂ , Y and H on the sp ³ carbon (picture) 4. cyclohexadienyl cation with NO ₂ at top, H and Y on the sp ³ carbon, positive charge adjacent (picture)

Doubtly AI · Accepted Answer

Answer: 2. cyclohexadienyl cation with NO ₂ at top carbon, H and Y on the sp ³ carbon, positive charge adjacent (picture) In the intermediate of electrophilic substitution, the positive charge is delocalised over the carbons ortho and para to the sp ³ carbon. An electron-withdrawing NO₂ is most destabilising if it sits on one of these carbons. In structures 1, 3 and 4 the carbon bearing NO₂ is ortho or para to the sp ³ carbon (the charge can fall on it). In structure 2 the NO₂ is on a meta carbon, so the charge never lands on it. Structure 2 is the most stable.

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

1 answer

Your answer