Orgo question, help!

[tooth123]

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2,2 dimethyl, 4 ethyl cyclohexanol.

If this molecule is drawn in its two chair conformations, what are the two chair conformations called?

diastereomers
enantiomers
same compound

??

 

[mightyrat]

I believe that stereochemistry is required to do this problem to identify whether the alcohol is in the axial/equatorial position and the same goes for the ethyl group, the methyl groups is irrelevant here since one would occupy the axial and the other would occupy the equatorial position.

That being said i believe the answer would be diastereomers because in one conformation (the most stable one) the alcohol and the ethyl groups are both equatorial and when you draw it out and see the rotation of the molecules you would see that the first carbon bearing the alcohol is an "R" configuration while the 4th carbon bearing the ethyl is an "S" configuration. Therefore, when you do the ring flip, that would invert giving you the opposite of that...alcohol is the S while the ethyl is the R which would identify it as the diastereomer.

Like i said i think stereochemistry needs to be addressed before this problem can be examined more closely but thats my best guess. Correct if im wrong please

 

[27Teeth]

diastereomer is the correct answer. 2 groups in one of the carbons are the same... so it doesn't matter which way they are drawn. However, the other group can be axial or equatorial, changing the R or S configuration of only one carbon so it's a diastereomer.

 

[tooth123]

diastereomer is the correct answer. 2 groups in one of the carbons are the same... so it doesn't matter which way they are drawn. However, the other group can be axial or equatorial, changing the R or S configuration of only one carbon so it's a diastereomer.

thanks (to the both of you)!

can anyone help with the other gchem question i posted 🙄

 

[SoulPower]

I'm pretty sure they are the same compound actually. There is no inversion of configuration when a chair conformation "flips" from equatorial to axial and vice versa. They are technically conformational isomers or the same molecule.

This makes sense because if this compound is made in solution it will invariably switch between these two conformations but optical activity will be sustained meaning no R or S switching.

And its definitely not a diastereomer, in order to be a diastereomer there must be two chiral carbons, which means that if the groups are S and S, its diastereomer would be S and R or R and S but not R and R, that'd be the enantiomer.

 

[mightyrat]

I'm pretty sure they are the same compound actually. There is no inversion of configuration when a chair conformation "flips" from equatorial to axial and vice versa. They are technically conformational isomers or the same molecule.

thats the whole point behind a ring flip lol the inversion of the groups would determine the relationships between two groups..in some cases that doesnt matter but in here it does.

You also mentioned that you need two chiral carbons, well thats there, if you draw out the chair you would see that the alcohol carbon is a chiral one (1-OH, 2-CH(CH3)2, 3-CH2, 4-H) those are the substituents on that carbon, the fourth carbon is also chiral, remember you have to go past the carbon thats directly attached to determine chirality.

I was actually stuck between diastereomers and enantiomers, i did the configuration and it came out to be R and S that means a flip would give S and R, if you draw that out you will see what im talking about.

 

[Laceigh]

I'm pretty sure they are the same compound actually. There is no inversion of configuration when a chair conformation "flips" from equatorial to axial and vice versa. They are technically conformational isomers or the same molecule.

This makes sense because if this compound is made in solution it will invariably switch between these two conformations but optical activity will be sustained meaning no R or S switching.

And its definitely not a diastereomer, in order to be a diastereomer there must be two chiral carbons, which means that if the groups are S and S, its diastereomer would be S and R or R and S but not R and R, that'd be the enantiomer.

I immediately thought it's the same compound too... I would trust this person, he/she got a 28 on OC

 

[orgohacks]

I immediately thought it's the same compound too... I would trust this person, he/she got a 28 on OC

Dude, it's the same compound. You haven't broken any bonds. You've just done bond rotations.

To get a diastereomer you would have to flip the orientation of one bond (i.e. break bonds).
To get the enantiomer you would have to flip the orientation of two bonds in this case.

 

[SoulPower]

My bad, I quickly looked over it and thought it was cyclohexane* not -ol. But the point still stands that there is no inversion of configuration.

Edit: It's actually easier to see this if you draw it in one plane, as a hexagon. Since switching chair configs still means that the bond coming at you is still coming at you regardless of the conformation and the bond away from you is still pointing down. You will see that there is no inversion or bonds broken. Therefore they are in fact the same compound.