In which of the following pair of carbocations, the first carbocation is more stable than the second? (i) CH 2 = CH − C + H 2 and CH 2 = CH − CH 2 − C + H 2 (ii) CH 3 − NH − C + H 2

Question

In which of the following pair of carbocations, the first carbocation is more stable than the second?

(i) $CH_{2} = CH - C + H_{2}$ and $CH_{2} = CH - CH_{2} - C + H_{2}$

(ii) $CH_{3} - NH - C + H_{2}$ and $C + H_{2} - OH$

(iii) $CH_{3} - O - CH_{2} - C + H_{2}$ and $CH_{3} - O - C + H_{2}$

(iv) $CH_{3} - C + H - CH_{2} CH_{2} CH_{3}$ and $CH_{3} CH_{2} - C + H - CH_{2} CH_{3}$

TestHub · Accepted Answer

In (i) ; whereas CH₂=CH–CH₂–CH₂ ⊕ shows no resonance effect. In (ii) Although + CH₂–OH also shows resonance, oxygen, being less basic, contributes to a lesser extent than nitrogen. In (iii) ; whereas no resonance occurs in CH₃–O–CH₂–CH₂ ⊕ . In (iv) CH₃–CH⁺–CH₂–CH₂–CH₃ has six hyperconjugative structures; whereas CH₃–CH₂–CH⁺–CH₂–CH₃ has just five hyperconjugative structures.

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