Diastereomers
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eg. 1:
1 and 2 have the same molecular formula and the same structural formula and, therefore, are stereoisomers. 1 and 2 are not mirror images of each other. Thus, they are diastereomers.
eg. 2:
3 and 4 have the same molecular formula and the same structural formula and, therefore, are stereoisomers. 3 and 4 are not mirror images of each other. Thus, they are diastereomers.
eg. 3:
5 and 6 have the same molecular formula and the same structural formula and, therefore, stereoisomers. 5 and 6 are not mirror images of each other. Thus, they are daiastereomers.
Cis-Trans isomers are a subset of diastereomers; all cis-trans isomers are diastereomers, but not all diastereomers are cis-trans isomers.
- see also enantiomers