Stereochemistry

Stereochemistry, a subdiscipline of chemistry, involves the study of the relative spatial arrangement of atoms that form the structure of molecules and their manipulation. the spatial arrangement of atoms and groups in a compound and its relation to the properties of the compound. Stereochemistry is concerned with chiral molecules and stereoisomers. The first stereochemist could be said to be Louis Pasteur who, in 1849, noted tartaric acid salts from wine vessels rotated plane polarized light, while tartrate salts from other sources did not have the same effect.

Types of Stereochemistry

Enantiomers

Enantiomers are structures that are mirror images of one another that arenon-superimposable. Non-superimposable means that no matter what way you rotate it, you will not be able to place it directly on top of the other facing the same way. You can easily demonstrate this with your hands because your hands are also non-superimposable, as you cannot place your hands on top of one another with your thumbs facing in the same direction, while your palms face the same way.

Diastereomers

Diastereomers are stereoisomers that are not enantiomers; that is, they are distinct molecules with the same structural arrangement of atoms that are non-superimposible, non-mirror images of each other. Consider the following representations of tartaric acid

In tartaric acid, both of the central carbon atoms are stereogenic centers. Thus, they both must be assigned R or S configurations according to the Cahnï¿½Ingoldï¿½Prelog system. The first two molecules shown above, (2S,3S)-tartaric acid and (2R,3R)-tartaric acid, are clearly enantiomers of each other since they are mirror images.

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