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Question: Which one of the following carbocation is most stable? A. \({(C{H_3})_3}C\mathop C\limits^ + {H_2}...

Which one of the following carbocation is most stable?
A. (CH3)3CC+H2{(C{H_3})_3}C\mathop C\limits^ + {H_2}
B. (CH3)3C+{(C{H_3})_3}\mathop C\limits^ +
C. CH3CH2C+CH2C{H_3}C{H_2}\mathop C\limits^ + C{H_2}
D. CH3C+HCH2CH3C{H_3}\mathop C\limits^ + HC{H_2}C{H_3}

Explanation

Solution

Chemical species bearing a positive charge on carbon and carrying six electrons in its valence shell are called carbocations. The stability of carbocations follows the order:
3∘>2∘>1∘3^\circ > 2^\circ > 1^\circ

Complete step by step answer: The order of stability of carbocations can be explained based on the following factors:
Inductive effect: The stability of the carbocation directly proportional to +I effect of the alkyl group.
Resonance effect: carbocations in which +vely charged carbon is attached to a double bond or a benzene ring are stabilized by resonance.
Hyperconjugation: effect: The relative stability of carbocations can be explained as more will be the ∝ hydrogen, more will be hyperconjugative structure and more will be stability.

For the case of the above options

       ![](https://www.vedantu.com/question-sets/b0fc3007-5d6c-472c-9c4e-91d08253822f5058371883682241841.png)(A)

(B)

(C)

(D)

In the case of option A, there is only one alkyl group attached to the carbon-containing + charge. In option B there are 3 alkyl groups and in the case of options C and D, there are 1 and 2 alkyl groups respectively. As more will be the alkyl group more will be the electron-donating effect i.e. +I effect which stabilizes the dispersal of + charge on carbocation. Hence option B is more stable. And if we talk about the resonance it exists only in the case of benzene and double-bonded carbocation.
And according to the hyperconjugation effect in the case of option B, there is maximum ∝hydrogen so maximum hyperconjugative structures are there. Hence the maximum will be stability.
Hence the correct option is B.

Note: ∝-hydrogen is that hydrogen that is attached to the carbon bonded with the carbocation. carbocations are highly reactive species and reactivity order is just the opposite of stability order.