isomerize

Isomerize refers to the process of converting a molecule into one of its isomers, compounds that share the same molecular formula but differ in the arrangement of atoms or in spatial orientation. Isomerization covers both structural (constitutional) isomers, where connectivity changes, and stereoisomers, where connectivity remains the same but geometry or chirality differs.

Types of isomerization include geometric (cis/trans or E/Z) isomerization around carbon–carbon double bonds, and optical isomerization involving enantiomers and diastereomers. Keto–enol tautomerization is often cited as a related interconversion between tautomeric forms with different bonding patterns. Isomerization can also involve rearrangements that change ring size or skeletal connectivity through various rearrangement mechanisms.

Isomerization proceeds via several mechanisms, commonly driven by heat, light, or catalysts. Industrially, alkane isomerization converts straight-chain hydrocarbons into branched isomers to improve fuel octane ratings using acidic or bifunctional catalysts. In organic synthesis, sigmatropic and other rearrangements redistribute bonds to form different isomers. Photochemical isomerization uses light to induce geometric changes, as seen in stilbene or azobenzene photoisomerization.

In biology, isomerization is catalyzed by isomerase enzymes that rearrange atoms within a molecule or convert one stereoisomer into another. Notable examples include phosphoglucose isomerase and triose phosphate isomerase, which participate in carbohydrate metabolism by interconverting specific sugars or sugar phosphates.

Because isomerization changes structure without altering the molecular formula, it can significantly affect physical properties, reactivity, and biological activity, making it a central concept in chemistry, biochemistry, and materials science.