Stereoizomery

Stereoisomers are a type of stereoisomer, which are chemical compounds that have the same molecular formula and the same atomic connectivity but differ in the three-dimensional arrangement of their atoms in space. This difference in spatial arrangement leads to distinct physical and chemical properties. The two main categories of stereoisomers are enantiomers and diastereomers.

Enantiomers are stereoisomers that are non-superimposable mirror images of each other, much like a left hand and a right hand. They have identical physical properties such as melting point and boiling point, but they differ in their interaction with plane-polarized light. One enantiomer will rotate the plane of polarized light in a clockwise direction (dextrorotatory, denoted by + or d), while the other will rotate it in a counterclockwise direction (levorotatory, denoted by - or l) by the same magnitude. This property is known as optical activity. Enantiomers are often found in biological systems, where they can have very different physiological effects.

Diastereomers, on the other hand, are stereoisomers that are not mirror images of each other. They can arise in molecules with more than one chiral center or in molecules containing double bonds. Unlike enantiomers, diastereomers generally have different physical properties, such as melting point, boiling point, and solubility. They also have different chemical reactivities. Cis-trans isomerism around a double bond is a common example of diastereomerism. When a molecule has multiple chiral centers, different combinations of configurations at these centers can lead to diastereomeric relationships.

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