OChem question

[DemQ]

Advertisement - Members don't see this ad

the answer on topscore is that they are enantiomers. I thought enantimoers are non sup. imposable. Why not meso or identical compounds ?



Uploaded with ImageShack.us

 

[DQLEUCD]

the answer on topscore is that they are enantiomers. I thought enantimoers are non sup. imposable. Why not meso or identical compounds ?



Uploaded with ImageShack.us

Flip one and you have the mirror image. If you flip one of those, it'll be the exact same molecule so it's identical and yes they are super-imposable. Try it and you will see that they are. They are not meso because if you fold it in half, it's not the mirror image of each other one is pointing up and other is pointing down. If both the methyl's were pointing up then they would be meso but they are not so they are identical molecules.

 

[UndergradGuy7]

As the above person said, because the CH3 groups are trans to each other it is an enantiomer. If they were cis, then they would be superimposable.

Look at the molecule on the left. If you flipped it, you would get something like this

the CH3 groups go in the other direction compared to the molecule on the right. So they are enantiomers.

 

[UCB05]

Flip one and you have the mirror image. If you flip one of those, it'll be the exact same molecule so it's identical and yes they are super-imposable. Try it and you will see that they are. They are not meso because if you fold it in half, it's not the mirror image of each other one is pointing up and other is pointing down. If both the methyl's were pointing up then they would be meso but they are not so they are identical molecules.

They are not superimposable no matter what way you turn, rotate, or conform it, as when you line up the 1,3 methyl groups, the original (R,R) figure will have axial-equatorial orientation, while the (S,S) mirror image will have equatorial-axial orientation (and vice-versa). Since they are distinct and nonsuperimposable, they are not meso nor identical. They are enantiomers. It might be easier to visualize if you drew it out in chair conformation.

 

[DemQ]

OHh the "H3"s do not line up if u flip one so it cannot be identical compound. I c it !

if u guys have an example of identical compounds, can you please post it.

and thanks for the reply guys

 

[DQLEUCD]

OHh the "H3"s do not line up if u flip one so it cannot be identical compound. I c it !

if u guys have an example of identical compounds, can you please post it.

and thanks for the reply guys

If you can superimpose (flip) one so that it matches the other. Best example is the letter A, do a 180 with it and you won't be able to tell them apart. To test yourself, use the example above. Leave the first one alone and do a 180 with the other one and lie it on top of the first one and see if it lines up perfectly or not. Then you will see why they are enantiomers. When you think of enantiomers think of "an ant in a mirror." Also good rule of thumb for an identical compound is that the majority of them do not have a chiral center well almost all. I think there are a couple of exceptions.

 

[2PacClone23]

Isn't the answer "Identical"?

 

[ZFT]

the stereochemistry isn't shown?.....you don't know if the methyls are pointing in or out

 

[DemQ]

if u flip one, the "H3"s do not line up. so they cannot be identical i guess

 

[DoCt0rPeTe]

See it now?

They draw the rings that way to throw you off. If you have doubts, just calculate R and S and you will see that they are indeed enantiomers.

 

[DQLEUCD]

if u flip one, the "H3"s do not line up. so they cannot be identical i guess

You are flipping the whole molecule. Whatever was pointing towards the page is now pointing out of the page and visa versa.

 

[orgohacks]

See it now?

They draw the rings that way to throw you off. If you have doubts, just calculate R and S and you will see that they are indeed enantiomers.

Exactly. This is a good check to do if you're not sure if you're dealing with the same molecule or not.

 

[chromosome21]

See it now?

They draw the rings that way to throw you off. If you have doubts, just calculate R and S and you will see that they are indeed enantiomers.

+1.. it's enantiomers