Isomeran

Isomeran is a term that occasionally appears in older or non-English texts to refer to compounds that share a molecular formula but have different arrangements of atoms. In contemporary chemistry, the standard term is isomer, and the study of their relationships is called isomerism. Because isomeran is not widely standardized in modern nomenclature, its precise meaning can vary by source, and it is not commonly used in current IUPAC references.

Isomerism is typically divided into structural (constitutional) isomers, where connectivity among atoms differs, and stereoisomers, where the same connectivity is arranged in space differently. Structural isomers include examples such as n-butane and isobutane (both C4H10) or ethanol and dimethyl ether (both C2H6O). Stereoisomers encompass enantiomers (non-superimposable mirror images) and diastereomers, as well as geometric isomers like cis and trans forms around double bonds. Conformational isomers arise from rotations about single bonds and can interconvert by relatively small energy barriers.

Physical properties such as boiling and melting points, solubility, and even biological activity can differ markedly between isomers. Distinguishing and separating isomers often relies on spectroscopic methods (NMR, IR) and chromatographic techniques, with chiral resolution used to separate enantiomers when necessary.

In chemistry and related fields, recognizing isomerism is fundamental to understanding reactivity, mechanism, and function. The term isomeran is not widely used in modern references; readers are generally advised to use isomer or isomerism to describe these phenomena.

See also: isomer, stereochemistry, enantiomer, diastereomer, geometric isomer, conformational isomer, isomerization.