Most stable confirmation?  [ENDORSED]

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Jamie_Cole_2N
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Joined: Wed Sep 21, 2016 1:58 pm

Most stable confirmation?

Postby Jamie_Cole_2N » Sun Mar 19, 2017 10:49 pm

For a chair conformation of cyclohexane, with IUPAC name either cis- or trans- 1,4-dimethylcyclohexane, which confirmation is the most stable? And adding the methyls to two axials H's, two equatorial H's, or one axial and one equatorial would be more stable?

Vincent Tse 2B
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Re: Most stable confirmation?

Postby Vincent Tse 2B » Sun Mar 19, 2017 11:50 pm

The chair conformation of cyclohexane is most stable when the substituents are equatorial as this will minimize steric interactions between the "bulkiness" of the substituents and the H-atoms.

Jamie_Cole_2N
Posts: 12
Joined: Wed Sep 21, 2016 1:58 pm

Re: Most stable confirmation?

Postby Jamie_Cole_2N » Mon Mar 20, 2017 11:11 am

So, is trans- more stable in this case?

Chem_Mod
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Re: Most stable confirmation?  [ENDORSED]

Postby Chem_Mod » Mon Mar 20, 2017 11:35 am

Yes, trans-1,4-dimethylcyclohexane is the most stable geometric isomer in the chair conformation with both methyl's in the equatorial position.
See my last lecture and page 112 in my lecture notes.

Hyun Young Lee 2H
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Joined: Wed Sep 21, 2016 1:59 pm

Re: Most stable confirmation?

Postby Hyun Young Lee 2H » Mon Mar 20, 2017 4:28 pm

is the a,a or e,e always definitely cis or is it determined by looking at the shape of the structure ?


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