What does diastereomer mean?

1 Answer
Jul 31, 2016

Diastereomers are geometric isomers (typically a pair) that are not mirror images.

Explanation:

Cis and trans isomerism are clearly geometric isomers because they have the same connectivity, but are not mirror images. To resort to the well-worn example of #"2-butylene"#, in BOTH cis and trans isomers, #C1# connects to #C2#......connects to #C4#. Nevertheless, their geometry is clearly distinguishable. For organic molecules that have 2 chiral centres, there are 2 pairs of enantiomers, #R,R# and #S, S#, and #R,S#, and #S,R#. Sometimes, #S, R# is equivalent to #R, S#. Nevertheless #R,S# shares a diastereomeric relationship with #R,R# and #S,S#, the enantiomers.