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I understand that you can react enantiomers with a chiral molecule to resolve the enantiomers of interest into diastereomers.

However I do not understand how exactly the added chiral molecule can make the enantiomers of interest into diastereomers.

Can someone please explain the process/mechanism ?

For example: here is a picture from my textbook. enter image description here How are those two salts Diastereomers, even though they are mirror images of each other.

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  • $\begingroup$ The ways are probably numerous. One mechanism that I remember has the chiral counterpart on a column. So you would basically do like an ion exchange. You'd then flush the column to release the other enantiomer. See: en.wikipedia.org/wiki/Chiral_resolution $\endgroup$ – MaxW Nov 9 '15 at 7:23
  • $\begingroup$ Are you sure they are mirror images? Look at the salt as a whole, not the individual ions. $\endgroup$ – orthocresol Nov 9 '15 at 8:30
  • $\begingroup$ The example on UC Davis ChemWiki is better, as they also offer the actual physical data with the compounds: chemwiki.ucdavis.edu/Organic_Chemistry/Fundamentals/… $\endgroup$ – Martin - マーチン Nov 9 '15 at 9:36
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Enantiomers are mirror reflections, they have same physical and chemical properties. This like left and right hand.

Diastereomers have different physical and chemical properties. You can separate them on chromatography column or by crystallization.

In your example upper and bottom products are not mirror reflections. Mirror relection of upper product looks like:

enter image description here enter image description here

Just play with the 3D models in any drawing software to get the point.

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  • $\begingroup$ Ah. Thanks. So the anion salt has to be taken into account as well. I was under the impression that you would only have to look a the cation. $\endgroup$ – MOHAMMAD RAZA Nov 9 '15 at 13:19

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