O chem Question

[JustwantDDS]

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Why is the answer C?
Isn't the most stable conformation (less energy) equatorial?

 

[BioSeven]

I think it's because C has the largest groups attached to it and the chair-chair conversion would place those groups in an axial position...

 

[JustwantDDS]

ahhh
it just clicked
its which of these will be highest energy after chair conversion
ooook
i need to breathe and READ properly

 

[chromosome21]

ahhh
it just clicked
its which of these will be highest energy after chair conversion
ooook
i need to breathe and READ properly

lol.. relax.. this happens to everybody.

and yes, C has the highest energy barrier. It'd rather stay equatorial than going axial.

 

[Ibraiz]

Is the question asking for the most stable conformation? Is this what it means when it says which one is the highest energy barrier? My question is what is it mean by the highest energy barrier?

 

[JeweLie]

Is the question asking for the most stable conformation? Is this what it means when it says which one is the highest energy barrier? My question is what is it mean by the highest energy barrier?

the question is basically asking which would need the most energy to go thru a chair-chair interconversion. A is very unstable since it has 1,3 diaxial strain and 2 groups in equatorial position would be the most stable. thus to go thru that interconversion, not much energy would be needed b/c it wants to be stable.

however for C, it's already in a really stable equatorial conformation. It would take alot of energy for it to interconvert into a molecule that has 1,3 diaxial strain which makes it very unstable.

hope i explained this ok~

 

[rnbaxter]

yes the answer is C, because both substituents are in the equatorial position AND are in opposite planes. Therefore, it will require the most amount of energy to do a chair flip because it is in the most stable conformation.