Tautomer

A tautomer is one of two or more structural isomers that interconvert through migration of an atom, usually hydrogen, and a shift in bonding.

Tautomerization: The reversible interconversion of tautomers by atom migration and a shift in bonding. This process converts one tautomer into another.
Structural isomerism: Isomerism in which compounds share a molecular formula but differ in the connectivity of their atoms. Tautomers are a special case of interconverting structural isomers.
Keto–enol chemistry: The chemistry arising from interconversion and reactions of carbonyl compounds and their enol forms. Enol formation creates nucleophilic sites used in carbon–carbon bond-forming reactions.
Conformational isomerism: Isomerism caused by rotation around bonds without breaking the molecule’s connectivity. Conformers interconvert by bond rotation rather than atom migration and bond shifting.
Prototropic tautomerism: Tautomerism in which a proton moves between atoms as the bonding pattern changes. Hydrogen migration is the most common route between tautomers.
Chemical equilibrium: A dynamic state in which forward and reverse reactions occur at equal rates. A tautomeric sample can contain both forms in an equilibrium mixture.
Enolate: A resonance-stabilized anion formed by removing an alpha proton from a carbonyl compound. Enolates resemble enols in reactivity but are charged species, not tautomers.
Protonation: The addition of a proton to an atom, molecule, or ion. Protonation changes charge by adding a proton, unlike tautomerism’s internal rearrangement.
Keto–enol tautomerism: Interconversion between a carbonyl compound and an enol through proton transfer and bond rearrangement. It is a familiar example of hydrogen-shift tautomerism.
Proton transfer: A chemical process in which a proton moves from one atom or molecule to another. Many tautomeric shifts begin with transfer of a hydrogen nucleus.

Linked from 4 pages