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Consider the 4 cis-trans isomers for the above compound. In what way would the cis-trans isomers affect their heat of combustion.

I think that if the substituents are on alternating sides of the ring, then there will be minimum steric crowding. But is there anything else that would affect their heat of combustions?

UPDATE: Here is as far as I have gotten. Now I think for the methyl group on carbon 4, either conformation would be stable. I am guessing that an axial methyl group would be more stable, because the axial position is free from all types of steric repulsion (This is just a guess). Is this correct?

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    $\begingroup$ You need to consider the conformation of the ring. $\endgroup$
    – Karl
    Commented May 12, 2020 at 15:48
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    $\begingroup$ The t-butyl group will be equatorial then draw the possible diastereomers. Read this: chemistry.stackexchange.com/questions/118093/… $\endgroup$
    – user55119
    Commented May 13, 2020 at 2:20
  • $\begingroup$ @user55119 is it true that whenever we have a single group attached on a cyclohexane, it will take an equatorial position? And if we have more than one group, the most bulky group takes the equatorial position $\endgroup$ Commented May 13, 2020 at 6:46
  • $\begingroup$ No. For a single group on cyclohexane it is an equilibrium as a function of its effective size. The larger the group, the more equatorial. t-Butyl is essentially always equatorial. This might help: ursula.chem.yale.edu/~chem220/chem220js/STUDYAIDS i/Avalues.htm $\endgroup$
    – user55119
    Commented May 13, 2020 at 11:49
  • $\begingroup$ @user55119 OK, so after that what do we do? $\endgroup$ Commented May 13, 2020 at 13:34


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