Simun Mishra posted an Question
June 27, 2020 • 10:51 am 30 points
  • IIT JAM
  • Chemistry (CY)

Greater the ring size greater the stability so why cyclopropyle methyl carbocation is more stable then benzyl carbocation ?

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    Dinesh khalmaniya 1

    Dancing resonance is a hypothetical phenomenon which is shown in structures of carbocations attached directly to a 3 membered ring  Here we can see that +ve charge is dancing between the two structure which is like resonce. Hence this exeptional stability of C.P.M cation (cyclo propyl methyl cation is explained by dancing resonance concept.

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    Dinesh khalmaniya 1 best-answer

    This can be expanied on the basis of Dancing resonance concept. CH2+ has a vacant p-orbital and a very effective overlapping takes place between p-orbital and electron density of cyclopropane ,as shown if figure,and due to this its stability is very high. There is a conjugation between the sigma bond(lone pair) and +ve charge.

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  • Suman Kumar

    Since cyclopropane ring has angle strain so it try to reduce the angle strain so it has more 'p' character in the bond.

  • Suman Kumar

    This is experimentally determined and the reason given is dancing resonance

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