how can you distinguish between cis/trans with cyclohexene?

[Vapor1122]

...in chair conformation, that is.

I figured it was trans since one was axial and the other equitorial, but that's apparently not a factor since the answer was cis.

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[Flipper405]

...in chair conformation, that is.

I figured it was trans since one was axial and the other equitorial, but that's apparently not a factor since the answer was cis.

This is in fact cis because if you look carefully, they are both pointing down. If the diagram is drawn correctly, this will be the easiest way to tell.

You can also determine it based on knowledge of the chair conformation: when you have a cis-1,2 disubstituted cyclohexene ring like this, 1 substituent will always be axial and the other will be equatorial. If it is trans, both substituents will either be axial or equatorial. These arrangements are the only way to achieve the staggered arrangement that defines the chair conformation. Sorry if this is unclear... hopefully it helps.

 

[Vapor1122]

Awesome, thanks

 

[basarachobits]

That's a bit harder way to tell, since you have to memorize. If I were you I would draw out the missing hydrogens. and because both hydrogen bonded bonds are above the CH3, the molecule is cis. Otherwise, if it is trans. This method works for other cyclo molecule as well, so it's convinient if the problem changes.

 

[Saber tooth]

That's a bit harder way to tell, since you have to memorize. If I were you I would draw out the missing hydrogens. and because both hydrogen bonded bonds are above the CH3, the molecule is cis. Otherwise, if it is trans. This method works for other cyclo molecule as well, so it's convinient if the problem changes.

yah simply draw out the remaining H's then compair the two groups... if both of the groups are below the C's of the ring then they are cis, similarly if both are above they are also cis.... However if one Group is above a ringed Carbon and the other group, no matter where on the ring is below its Carbon ring then the two are trans hope it helps

 

[as2007]

that was CIS because both methyl groups are pointing down.

 

[doctorosar]

you know this is cis because first: its 1,2 axial and equatorial if you remember 1,2 or 1,4 axial and equator means that is cis. easy!

 

[Flipper405]

I have to say one thing that actually helped me a lot with cyclohexane rings is that I built it with molecular models and examined it in detail with all the various conformations (boat, half-chair, etc.) If you have or can get a hold of a molecular modeling set, it helps for various ochem topics.