Meso compounds

[mx41]

Which of the following molecules can exist as meso compound?
1) cis-1,2-cyclopentanediol
2) trans-1,2-cyclopentanediol
3) 2,3-dihydroxybutane
4) #1 & #2
5) #2 & #3

I said the answer was 4.. how could #1 not be a meso compound?

The real answer is 5

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[silveryhair]

Should it say 1 and 3??? 2 is in trans, why would that be meso?

 

[rejuvenatedsoul]

where is this question from?

 

[mx41]

where is this question from?

This is from topscore, exam 1

 

[mx41]

Should it say 1 and 3??? 2 is in trans, why would that be meso?

It is meso because there arent any other chiral carbons in the compound, so if you did the enantiomer (or mirror image) of this compound, you get the same exact stereochemistry. thus it is meso

 

[drpj]

You mixed up the answer choices. The correct answers are actually cis-1,2-cyclopentanediol & 2,3-dihydroxybutane.

 

[rejuvenatedsoul]

i remember this from topscore. i say 1 and 3.

 

[silveryhair]

Erm, I don't really get what your saying, I'm guessing chad;s video might have confused you.
Check out this link.

http://en.wikipedia.org/wiki/Meso_compound

and go to the cis meso compounds part. It might help clarify it.

It is meso because there arent any other chiral carbons in the compound, so if you did the enantiomer (or mirror image) of this compound, you get the same exact stereochemistry. thus it is meso

 

[rnbaxter]

Question is kind of ******ed/difficult to think about because of the ring strain. However I would say 1 and 3 would be classified as the mesos. The trans 1,2 dihydroxycyclopentane can have D and L forms, so it shouldn't be meso.

 

[Troyvdg]

Question is kind of ******ed/difficult to think about because of the ring strain. However I would say 1 and 3 would be classified as the mesos. The trans 1,2 dihydroxycyclopentane can have D and L forms, so it shouldn't be meso.

ring strain does not affect a compounds ability to be meso.

trans 1,2 dihydroxycyclopentane is NOT meso, there's no plane of symmetry

 

[Dotoday]

cis-1,2-cyclopentanediol is the only meso compound among these choices. It is the only one that has chiral carbons and internal plane of symmetry. Others (including trans) do not have internal plane of symmetry.
Hope this helps.

 

[rnbaxter]

ring strain does not affect a compounds ability to be meso.

trans 1,2 dihydroxycyclopentane is NOT meso, there's no plane of symmetry

Take a cis 1,2 hydroxycyclohexane vrs a cis 1,3 hydroxycyclohexane. The 1,3 is the meso form...

 

[CANgnome]

Take a cis 1,2 hydroxycyclohexane vrs a cis 1,3 hydroxycyclohexane. The 1,3 is the meso form...

why isn't cis 1-2 meso?

 

[UCB05]

why isn't cis 1-2 meso?

It is.

 

[CANgnome]

It is.

i thought so

 

[chromosome21]

It is meso because there arent any other chiral carbons in the compound, so if you did the enantiomer (or mirror image) of this compound, you get the same exact stereochemistry. thus it is meso

This compound is NOT meso. What you're saying is not wrong, b/c the enantiomer would be the same as this molecule if you rotate it. And that is what makes the enantiomer and this compound to be the SAME molecule. However, a molecule to be a meso compound, there needs to have a plane of symmetry passing thru the molecule itself, which this molecule does not have. Therefore, this molecule is NOT meso.

In short, the enantiomer of this compound is the compound itself, and this compound is NOT meso.

the answer should be 1 and 3 in my opinion. The question asks which molecule "can" exist as a meso compound. The third choice "can" and "cannot" exist as a meso compound, but b/c of the type of the question, i'd say 3 "can" exist as a meso compound. My choices would be 1 and 3. #1 is definitely meso.

 

[UCB05]

This compound is NOT meso. What you're saying is not wrong, b/c the enantiomer would be the same as this molecule if you rotate it. And that is what makes the enantiomer and this compound to be the SAME molecule. However, a molecule to be a meso compound, there needs to have a plane of symmetry passing thru the molecule itself, which this molecule does not have. Therefore, this molecule is NOT meso.

In short, the enantiomer of this compound is the compound itself, and this compound is NOT meso.

the answer should be 1 and 3 in my opinion. The question asks which molecule "can" exist as a meso compound. The third choice "can" and "cannot" exist as a meso compound, but b/c of the type of the question, i'd say 3 "can" exist as a meso compound. My choices would be 1 and 3. #1 is definitely meso.

you might be getting your structure a bit mixed up. the enantiomer of the trans dihydroxycyclopentane is exactly that, an enantiomer. They are non-superimposable and are not the same molecule. meso and identical entantiomers kind of go hand-in-hand because the internal plane of symmetry is what allows the enantiomer to be "flipped" to become the original molecule.

 

[chromosome21]

you might be getting your structure a bit mixed up. the enantiomer of the trans dihydroxycyclopentane is exactly that, an enantiomer. They are non-superimposable and are not the same molecule. meso and identical entantiomers kind of go hand-in-hand because the internal plane of symmetry is what allows the enantiomer to be "flipped" to become the original molecule.

Thanks for the catch. I understood my mistake.

could you plz explain how trans-1,2-cyclopentanediol is meso? thanks

 

[orgohacks]

This compound is NOT meso. What you're saying is not wrong, b/c the enantiomer would be the same as this molecule if you rotate it. And that is what makes the enantiomer and this compound to be the SAME molecule. However, a molecule to be a meso compound, there needs to have a plane of symmetry passing thru the molecule itself, which this molecule does not have. Therefore, this molecule is NOT meso.

In short, the enantiomer of this compound is the compound itself, and this compound is NOT meso.

the answer should be 1 and 3 in my opinion. The question asks which molecule "can" exist as a meso compound. The third choice "can" and "cannot" exist as a meso compound, but b/c of the type of the question, i'd say 3 "can" exist as a meso compound. My choices would be 1 and 3. #1 is definitely meso.

I agree. #1 and #3.