iseerimise

Isomerization, in the Estonian context often referred to as isomeriseerimine or isomerization, is the chemical process of converting a molecule into another molecule that has the same molecular formula but a different arrangement of atoms. The resulting compounds, isomers, can be structural (constitutional) isomers with different connectivity, or stereoisomers such as cis/trans forms or enantiomers.

The process can proceed through various mechanisms. It may involve rearrangements of the carbon skeleton, bond breaking and reformation, or shifts of atoms or groups within the molecule. Isomerization can occur thermally or be driven by catalysts. Catalytic isomerization often proceeds via intermediates such as carbocations or metal-activated species, enabling rearrangements that would be unfavorable under simple thermal conditions. Broadly, there are structural isomerizations, where the connectivity changes, and stereochemical isomerizations, where the spatial arrangement around double bonds or chiral centers changes without altering the overall connectivity.

In industry, isomerization has practical importance in refining and petrochemistry. A key application is the conversion of straight-chain alkanes into branched isomers to improve gasoline octane ratings. This is typically accomplished in isomerization units using catalysts such as platinum on alumina or zeolite-based systems, under moderate temperatures and controlled pressures. Isomerization also encompasses reactions that adjust the stereochemistry of molecules, which can be important in the synthesis of pharmaceuticals and other fine chemicals.

Common examples include converting n-butane to isobutane and rearranging alkenes to achieve different cis/trans configurations. Isomerization is a fundamental concept in chemistry, closely related to broader ideas of isomerism and catalytic reforming.