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Topic: Stereochemistry - Chair conformations of Cyclohexane  (Read 11688 times)

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Offline Joules23

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Stereochemistry - Chair conformations of Cyclohexane
« on: June 02, 2008, 06:45:02 PM »


Please explain how these are enantiomers, i thought enantiomers were mirror images of each other, these are not mirror images.

also, im not to sure what conformers are, so please feel free to explain that too :)

Offline macman104

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Re: Stereochemistry - Chair conformations of Cyclohexane
« Reply #1 on: June 02, 2008, 06:56:35 PM »
What happens if you do a chair-chair interconversion (chair flip) to the conformer on the left?  If you have an axial chlorine and chair flip it, is it still axial?

A conformer is just a possible conformation of the molecule you are looking at.  It represents one possible existence of the entity you are looking at.

Offline Joules23

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Re: Stereochemistry - Chair conformations of Cyclohexane
« Reply #2 on: June 02, 2008, 07:04:37 PM »
ahh ok, so when you flip it, the axials turn into equatorials.. but then why wouldnt they be identical molecules?

EDIT: okay i just did it with my models, now i see, thanks!

Offline macman104

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Re: Stereochemistry - Chair conformations of Cyclohexane
« Reply #3 on: June 02, 2008, 07:41:25 PM »
ahh ok, so when you flip it, the axials turn into equatorials.. but then why wouldnt they be identical molecules?

EDIT: okay i just did it with my models, now i see, thanks!
Ah  models, very good that you have them.  They will be invaluable for stereochemistry and such.  Also, if you know how to assign priorities, you would see that the R,S assignments are flipped, which indicates enantiomers.

Offline Joules23

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Re: Stereochemistry - Chair conformations of Cyclohexane
« Reply #4 on: June 05, 2008, 08:26:18 PM »


Why arent these molecules identical ?? If you flip the chair conformation of either molecule you will get the other molecule...

Or is that what is meant by "conformer" they are the same (when one is flipped) but not the same (when left alone)?

Offline Yggdrasil

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Re: Stereochemistry - Chair conformations of Cyclohexane
« Reply #5 on: June 05, 2008, 10:36:56 PM »
Conformer means that they are molecules with identical connectivity and stereochemistry that differ by rotation about one or more bonds (i.e. they have different conformations).

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