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Well for starters, axial groups are those that point either directly up or directly down on our chair form of cyclohexane for example: |dw:1441936471814:dw| these are the positions of all our axial groups on the chair form of cyclohexane. in-fact, it is not advisable to have large groups at the axial position, because there is a phenomena called 1-3, di axial interactions, meaning that the electron clouds of certain groups will repel each-other making our chair conformation less stable. If possible, what will happen is something called a ring flip. the ring will flip to minimize some of the repulsion caused by the 1-3 di axial interaction and will stay in the more stable conformation more.
In your figure it translates to this |dw:1441936710898:dw|
All of the groups I circled groups are axial in this depiction; Well the CH3 should be also circled, i'm sorry for that. If I am correct, this molecule may under go a ring flip and when a ring flip happens all the groups that are axial become equatorial and all the equatorial groups become axial.
How do I know which group will sterically interact?
For this i'm not too sure but I believe there are 2 interactions at most possibly 3. the atoms have to be at the 3 position. so look at the axial group and label that as carbon 1, then count until you find the third atom and then look at the group that's axial. |dw:1441936984215:dw|
Consequently, the molecule will naturally flip if it can to minimize these 1,3-di-axial interactions, naturally this puts a-lot of strain on our molecule NOTE: These interactions only happen at groups that are in the axial positions. equatorial positions are irrelevant.
Just to show you how to do this and for anyone else who is reading this: |dw:1441937554093:dw|
Ring flips CAN and WILL happen but only if it results in fewer of these 1,3 di-axial interactions.
I understand what you are saying. Will the answer include the while group or just the carbon?
good question, I didn't specify. the 1-3 di-axial interaction will include only the group that is in the axial position bonded to the carbon on the ring, not the carbon itself. is that what you meant?
@sharmar25 the interactions will be between the two groups at the axial positions as shown, not necessarily the carbons in the ring. steric interaction implies repulsion between groups. Imagine each group as an electron cloud, two negative charges will repel, that's why the molecule tries to minimize this if it can. |dw:1441938341493:dw|
One last example: say if we had something like this: for instance an oxygen bonded to a hydrogen at one of the groups in the axial position. Say if we didn't have any other groups just hydrogen at the axial positions. This is also a 1,3 di axial interaction, although one of a different kind. it's possible that the lone pair of electrons on the oxygen will hydrogen bond to one of the nearby hydrogens. |dw:1441938504189:dw|
Yes. Thats what I was asking. Thank so much for your help.
Absolutely, hope this helps you and anyone else reading this take care
Yeah this was an awesome answer @greatlife44