Question: Are these compounds enantiomers?

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Attempt: The compounds given are mirror images. But if I rotated the three bonds in the third carbon (configuration will not change), I will get a meso compound (plane of symmetry) : enter image description here

So are these compounds enantiomers or meso compounds?

  • $\begingroup$ Aren't there some restrictions for flipping/rotation of Fischer projections . $\endgroup$ Commented Oct 22, 2015 at 10:58
  • $\begingroup$ Answer given is meso. At room temperature, rotation about any one single bond can take place. Interchanging 3 groups will not change configuration. $\endgroup$
    – Aditya Dev
    Commented Oct 22, 2015 at 11:00
  • $\begingroup$ Realistically for compounds with more than 1 chiral centre, fisher projection is require to determine if compound is mesoisomer or enantiomers. If someone draws like that then dont rotate carbons to avoid confusion and just assume if it is meso or enantiomers based on diagram alone. $\endgroup$
    – Luci
    Commented Sep 22, 2023 at 9:07
  • $\begingroup$ An unfortunate drawing of the original projections Place H at top and bottom easy to see it is an R,S configuration hence meso. $\endgroup$
    – jimchmst
    Commented Sep 22, 2023 at 16:02

1 Answer 1


You are right, the 2 structures are equivalent and the substance has a plane of symmetry and is a meso compound. When in doubt, make a 3D model if possible.


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