Diastereomeeriä

Diastereomeeriä is the Finnish term for diastereomers. Diastereomers are stereoisomers that are not mirror images of each other. This means that if you have two molecules that are diastereomers, they will have at least two chiral centers, but the configuration at one or more of these chiral centers will be different, while the configuration at others will be the same. Unlike enantiomers, which are non-superimposable mirror images and thus have identical physical properties (except for their interaction with plane-polarized light), diastereomers have different physical properties such as melting point, boiling point, and solubility. They also have different chemical reactivity towards other chiral molecules.

The term "diastereomer" is used when referring to molecules that are stereoisomers but are not enantiomers. A common example arises in molecules with multiple chiral centers. For instance, in a molecule with two chiral centers, there can be up to four possible stereoisomers. Two of these pairs will be enantiomers, while the isomers that are not mirror images of each other are diastereomers. For example, in tartaric acid, which has two chiral centers, there are three stereoisomers: (R,R)-tartaric acid, (S,S)-tartaric acid, and (R,S)-tartaric acid (which is also known as meso-tartaric acid). The (R,R) and (S,S) forms are enantiomers. The (R,R) form is a diastereomer of the (R,S) form, and similarly, the (S,S) form is a diastereomer of the (R,S) form. Meso compounds, which are achiral despite having chiral centers due to internal symmetry, are also diastereomers of other stereoisomers of the same compound.