Carbocation



  • 0_1551017069610_IMG_20190224_193400.jpg
    Ans: a
    Why opt a is the answer? Why not b? What is the meaning of half life of carbocation?

    Doesn't only radioactive substances have half life? Please explain.



  • @anag
    The lifetime of a carbocation is nothing but the reciprocal of the rate coefficient (ks) for its disappearance in a given solvent, possibly by solvation.
    I'm guessing half life is when half concentration of the carbocations disappear.

    As for the answer, all options given are 3° so we gotta check which of the compounds attached are very stable.
    A is a 3° cation in attachment with CMC. Very stable. Second only to benzylic carbocation, but since we don't have bezylic, we consider it most stabel as of yet.
    B is benzylic attached to only one.
    C is 3° cation in attachment to cyclohexane.
    D is 3° cation



  • @advait-girap said in Carbocation:

    @anag
    The lifetime of a carbocation is nothing but the reciprocal of the rate coefficient (ks) for its disappearance in a given solvent, possibly by solvation.
    I'm guessing half life is when half concentration of the carbocations disappear.

    As for the answer, all options given are 3° so we gotta check which of the compounds attached are very stable.
    A is a 3° cation in attachment with CMC. Very stable. Second only to benzylic carbocation, but since we don't have bezylic, we consider it most stabel as of yet.
    B is benzylic attached to only one.
    C is 3° cation in attachment to cyclohexane.
    D is 3° cation

    Here all options are not 3° since opt b (benzylic carbocation). Why can't option b be the answer?

    What is the meaning of CMC? Why is a 3-membered ring (opt a) more stable than a 6-membered ring (opt c) ? Please explain.



  • @anag Here all options are not 3° since opt b (benzylic carbocation).

    What is the meaning of CMC? Please explain.

    Why is a 3-membered ring (opt a) more stable than a 6-membered ring (opt c) ?

    Does it mean that dancing resonance is more stable than ordinary resonance? Please explain.



  • @pranay-singh here there is no carbanion in the options. Only carbocation is present.

    Can you please explain the doubts written above?


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