Chirality question

[sanguinee]

Is it true that molecule B is achiral and molecule A is chiral?

I thought both of the molecules are symmetrical and thus achiral, regardless of molecule B being cis while A is trans.


also, for the following question, aren't both molecules enantiomers since they're both non superimposable mirror images?

The correct answer is apparently only A.


thank you!

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[aldol16]

Is it true that molecule B is achiral and molecule A is chiral?

They're both chiral and not symmetrical. Draw it in 2D representation. They're diastereomers.

also, for the following question, aren't both molecules enantiomers since they're both non superimposable mirror images?

B is the same molecule as the one shown. Look at it from behind the plane of the page.

 

[sanguinee]

@aldol16, For the second question: that's what I thought, so I think the explanation is incorrect.

As for the first question, isn't B a meso compound though? There's an internal plane of symmetry, which would ultimately make the compound achiral even though there are two chiral centers.
I assumed the same logic is applicable for compound A, but based on the explanation and correct answer (A being chiral and B being achiral), I'm assuming stereochemistry (the groups being trans) does not make it a meso compound?

 

[aldol16]

@aldol16, For the second question: that's what I thought, so I think the explanation is incorrect.

The explanation is correct. You misinterpreted my response. B is a meso form of the compound that is given (not A). Therefore, it's the same thing. If it's the same thing, it's obviously not an enantiomer.

As for the first question, isn't B a meso compound though? There's an internal plane of symmetry, which would ultimately make the compound achiral even though there are two chiral centers.
I assumed the same logic is applicable for compound A, but based on the explanation and correct answer (A being chiral and B being achiral), I'm assuming stereochemistry (the groups being trans) does not make it a meso compound?

I apologize. B is a meso compound. A is not though. Draw it in 2D. You have a cyclohexane ring with one substituent "up" and the one to the right of it "down." Now flip the stereochemistries. You can't superimpose the two.

 

[sanguinee]

Thanks @aldol16