The key difference between axial and equatorial position is that axial bonds are vertical while equatorial bonds are horizontal. The terms axial and equatorial are important in showing the actual 3D positioning of the chemical bonds in a chair conformation cyclohexane molecule.
Is axial or equatorial more stable?
A conformation in which both substituents are equatorial will always be more stable than a conformation with both groups axial.
What is a chair flip?
Ring flip (chair flip): The conversion of one cyclohexane chair conformation into another, by rotation around single bonds. Cyclohexane ring flip causes axial substituents to become equatorial, and equatorial substituents to become axial.
Is axial a wedge or dash?
It’s important to realize that a chair flip does not turn a “wedge” into a “dash” but instead turns an “axial” into an “equatorial”.
Why is axial higher energy than Equatorial?
Note that in the conformation where methyl is axial, there is a gauche interaction between the axial methyl group and C-3. This is absent in the conformation where methyl is equatorial. This gauche interaction is an example of van der Waals strain, which is what makes the axial conformer higher in energy.
Which chair conformation is most stable?
The most stable conformation of cyclohexane is the chair form shown to the right. The C-C-C bonds are very close to 109.5o, so it is almost free of angle strain. It is also a fully staggered conformation and so is free of torsional strain.
Does axial or equatorial react faster?
The axial sulfonyl chloride 6 was found to react 71 times faster than the equatorial epimer 8 with triethylamine in the presence of aniline at -25″, a reaction which evidently proceeds via the sulfene 7.
What placement Axial vs Equatorial and carbon groups created more shifting?
What placement (axial vs equatorial) and carbon groups created more shifting? Axially placed groups with higher steric strain, isopropyl and tert-butyl, created more shifting. What trend in axial to equatorial energy differences did you observe with the different carbon groups placed on the molecule?
What is the difference between axial and equatorial methyl cyclohexane?
Because diastereomers have different energies, one form is more stable than the other. Equatorial methylcyclohexane is more stable than axial methylcyclohexane. In fact, it is usually the case that the equatorial conformation of a substituted cyclohexane is more stable than the axial conformation.
Is wedge axial or equatorial?
In all cases, a substituent that was marked by a wedge or a dash in a 2-D drawing will remain that way, but in the chair conformation, the wedge might means axial “up” instead of equatorial “up” depending on whether it is a right- or left-handed chair.
What is the most stable chair conformation of menthol?
The second conformation is most stable because all groups are equatorial and there are no unfavorable diaxial interactions.
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