Question

Which of the following carbocation will be the most stable?


(a) (CH3)2CH+

(b) Ph3C+

(c) CH2=CHCH2+

(d) CH3CH2+

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Answer 1

The hyperconjugation involves the delocalisation of sigma electrons to the empty p orbital present at the alpha position as shown in the above image.

Hence, there is need of a sigma C−H bond of the sp

3

hybridized carbon atom which is present at alpha position with respect to the carbocation.

More the number of sigma C−H bonds at alpha position, more the number of hyperconjugating structures and more the stability. Hence structure (b) which is having nine sigma C−H bonds will be the most stable carbocation.