Diastereomeri

Diastereomers are a type of stereoisomer, which are molecules that have the same molecular formula and sequence of bonded atoms (constitution), but differ in the spatial arrangement of these atoms in three-dimensional space. Unlike enantiomers, which are mirror-image stereoisomers of chiral molecules, diastereomers are not mirror images of each other. Instead, they are distinct stereoisomers that share the same connectivity but differ in configuration at one or more stereocenters.

The term "diastereomer" originates from the Greek words *dia* (through) and *stereos* (solid or three-dimensional), reflecting the differing spatial orientations of atoms. Diastereomers exhibit different physical and chemical properties, such as melting points, boiling points, solubility, and reactivity, due to their distinct three-dimensional structures. This variation makes them easier to separate compared to enantiomers, which often require chiral resolution techniques.

Diastereomers commonly arise in molecules containing multiple stereocenters, such as amino acids, sugars, and complex organic compounds. For example, in a molecule with two chiral centers, there are three possible diastereomeric pairs (excluding enantiomers). The relationship between diastereomers can also occur in compounds with geometric isomerism, such as *cis*- and *trans*-alkenes, where the spatial arrangement of substituents differs around a double bond.

Identifying diastereomers often involves techniques like nuclear magnetic resonance (NMR) spectroscopy, chromatography, or crystallographic analysis. Understanding diastereomerism is crucial in fields such as organic synthesis, pharmacology, and materials science, where stereochemical control influences product properties and biological activity.