7.6 Meso Compounds

7.6 Meso Compounds

  • Each compound has two stereocenters.
    • These compounds are enantiomers because the configurations are different for both stereocenters.
    • If you were only given the first compound, you could have used the first method to draw the enantiomer.
  • Determine whether the compounds are diastereomers or enantiomers.
  • This is a topic that is hard to understand, so let's start with an analogy.
    • One of the twin brothers has a mole on the left side of his face, while the other has a mole on the right side of his face.
    • The brothers are mirror images of each other, and you can tell them apart by the mole.
    • Imagine that their parents had many sets of twins.
    • There are a lot of siblings, who are all brothers and sisters of each other, but they are grouped together.
  • When you have a lot of stereocenters in a compound, there will be many stereoisomers.
    • They will be grouped together into sets of enantiomers.
    • There will be many diastereomers in a molecule, but only one enantiomer.
  • The compound has five stereocenters, so it will have many diastereomers.
    • This compound will have many brothers and sisters because there are many possible compounds that fit that description.
  • A compound can be its own mirror image.
    • The compound will not have a twin, and the total number of stereoisomers will be an odd number.
    • You will find that your drawing will be the same compound as you started with if you try to draw the enantiomer using either of the methods we have seen.
  • The molecule has a plane of symmetry.
  • You will find that you are drawing the same thing again if you try to draw the enantiomer using either method.
    • The molecule does not have a twin.
  • When we have an internal plane of symmetry, this can happen.
    • It can happen when the compound has a center of inversion.
  • The compound does not have a plane of symmetry, but it does have a center of inversion.
    • We can regenerate the same thing if we invert everything around the center of the molecule.
  • It's enough to look for planes of symmetry.
  • Your second drawing is the enantiomer of the original compound.