diastereomérov

Diastereomers are stereoisomers that are not mirror images of each other. This means that if you have two compounds that are diastereomers, they will have the same molecular formula and connectivity, but their three-dimensional arrangement of atoms will be different, and they will not be superimposable upon reflection. This distinguishes them from enantiomers, which are stereoisomers that are non-superimposable mirror images.

The difference in three-dimensional arrangement in diastereomers arises from the presence of multiple chiral centers within a molecule. For a molecule with n chiral centers, there can be up to 2^n stereoisomers. Diastereomers exist within this set of possible stereoisomers when two molecules share at least one, but not all, chiral centers with the same configuration. For example, in a molecule with two chiral centers, say at positions 1 and 2, if isomer A has R configuration at both centers and isomer B has R at center 1 and S at center 2, then A and B are diastereomers. If isomer C has S at both centers, then A and C are enantiomers, and B and C are also diastereomers.

Diastereomers have different physical and chemical properties, unlike enantiomers which often have very similar physical properties and identical chemical properties in achiral environments. Diastereomers can have different melting points, boiling points, solubilities, and spectroscopic properties. They can also react at different rates with achiral reagents and can be separated using standard techniques like chromatography or fractional crystallization. This difference in properties makes the separation and identification of diastereomers more straightforward than that of enantiomers.