diastereomers

{| align="right" class="wikitable" |- !colspan="2"|Diastereomers that are also epimers |- |bgcolor="#FFFFFF"| 150px |bgcolor="#FFFFFF"| 150px |- |bgcolor="#FFFFFF"| 166px |bgcolor="#FFFFFF"| 144px |- | D-threose | D-erythrose |}

In stereochemistry, diastereomers (sometimes called diastereoisomers) are a type of stereoisomer. Diastereomers are defined as non-mirror image, non-identical stereoisomers. Hence, they occur when two or more stereoisomers of a compound have different configurations at one or more (but not all) of the equivalent (related) stereocenters and are not mirror images of each other. When two diastereoisomers differ from each other at only one stereocenter, they are epimers. Each stereocenter gives rise to two different configurations and thus typically increases the number of stereoisomers by a factor of two.