3
$\begingroup$

I am dealing with two conformations of cis-1,4-dimethylcyclohexane. One conformation is di-axial, and the other one is di-equatorial. Why does di-axial have higher strain energy. I would make sense if the molecule was 1,3-dimethylcyclohexane because then it would the steric hinderance that would cause higher energy. Is it similar with 1,4-.. conformation? If its not steric repulsion, what factors cause di-axial to have higher strain energy?

$\endgroup$
  • $\begingroup$ Di-axial and di-equatorial in cis-1,4-dimethylcyclohexane in a chair conformation? $\endgroup$ – Klaus-Dieter Warzecha Mar 9 '15 at 9:01
  • 1
    $\begingroup$ Look at your molecule again. Are you sure you are not talking about trans-1,4-dimethylcyclohexane? In the cis-isomer both methyl groups must point in the same direction relative to the ring. That means one must be equatorial and one must be axial. $\endgroup$ – Ben Norris Mar 9 '15 at 10:44
4
$\begingroup$

You can't have both in a chair conformation!

  1. If the methyl groups in 1,4-dimethylcyclohexane adopt a bis-axial orientation, they are trans and they stay trans after ring flip:
    enter image description here

  2. If your 1,4-dimethylcyclohexane is cis-substituted the orientation of the methyl groups is axial and equatorial, respectively:
    enter image description here

| improve this answer | |
$\endgroup$
  • $\begingroup$ They could be both equatorial in a boat or twisted configuration, though. Currently I am not too sure which is the thermodynamically most stable one. $\endgroup$ – Martin - マーチン Mar 10 '15 at 8:42

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.