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Shristy posted an Question
June 02, 2020 • 04:41 am 30 points
  • IIT JAM
  • Chemistry (CY)

Since heat of combustion of cyclohexane is more than cyclopentane than why cyclohexane is stable than cyclopentane ????

since heat of combustion of cyclohexane is more than cyclopentane than why cyclohexane is stable than cyclopentane ????

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  • Komal

    if hoc per carbon of cyclohexane is 17kj then it should be less stable because hoc is inversely proportional to stability

  • Suman Kumar best-answer

    Shristy This is the actual data of Hoc in fourth column.it is per mole in kj

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    You can easily compare 3129/5 & 3656.8/6. Hope you have completely understood

  • Suman Kumar Best Answer

    This is just rough data used for simplicity.

  • Suman Kumar best-answer

    For example Hoc for cyclopentane is 100 kj then per carbon=20 kj and hoc for cyclohexane is 102 then per carbon will be 17 then cyclohexane is more stable. In this way hoc data is used for stability.

  • Suman Kumar

    lets say for example cyclopentane has 100 kj of hoc then per carbon hoc = 20 and cyclohexane has 102 kj of hoc then per carbon is 17 kj.

  • Suman Kumar

    Shristy for any hydrocarbon stability on basis of Hoc is compared per carbon.

  • Suman Kumar

    You are absolutely right. Heat of combustion (HOC) of cyclohexane is more than cyclopentane. For comparison of stability it is always HOC per carbon is seen in which HOC of cyclohexane comes lesser.

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    HOC is inversely proportional to stability then why cyclohexane is more stable than cyclopentane although cyclohexane has more HOC

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    I have tried to explain you. Still ask if you don't get Shristy

  • comment-profile-img>
    Lingareddy 1

    Cyclopentane is slightly more stable because it can relieve some of the bond strain by buckling the ring and pushing one carbon out of the plane. Cyclohexane has effectively zero strain, since all the carbons now have exactly the correct bond angle for optimum overlap of their orbitals with their neighbours.

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