Isomeriza

Isomeriza is a term used in chemistry to describe the process of converting one molecule into another that has the same molecular formula but a different arrangement of atoms or stereochemistry. The concept underlies the broader idea of isomerization, and the verb form appears in several Romance languages (for example, isomerizar in Spanish or isomerizzare in Italian). In English, the corresponding verb is isomerize or isomerise.

Isomerization can be categorized in several ways. Structural (constitutional) isomerization changes the connectivity of atoms within a molecule, producing a different constitutional isomer. Stereoisomerization alters the spatial arrangement without changing connectivity, such as cis–trans (geometric) isomerization around a double bond or the interconversion of enantiomers at a chiral center. Tautomerization, a related process, involves rapid intramolecular proton transfer that shifts functional groups, as in keto–enol tautomerism.

Typical causes include heat, light, and the action of catalysts. Acids, bases, or metal catalysts in the presence of suitable substrates can promote rearrangements, sometimes under milder conditions with specialized catalysts such as zeolites or homogeneous metal complexes. Industrially, isomerization reactions are used to improve fuel quality (for example, increasing octane ratings) and to prepare intermediates in chemical synthesis. In biology, isomerization is carried out by isomerase enzymes, which catalyze rearrangements such as cis–trans conversions or the conversion between sugar phosphates.

Understanding isomerization is important for predicting product distribution, optimizing synthesis, and evaluating the stability and activity of chemical and biological systems. See also isomerase, tautomerization, and epimerization for related concepts.