The term describes simple reversible and generally rapid isomerizations or degenerate rearrangements involving the formation and rupture of single and/or double bonds, without migration of atoms or groups; e.g.
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See also: fluxional, tautomerism
Source:
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1175 (https://doi.org/10.1351/pac199466051077)