Title: synchronous
Long Title: IUPAC Gold Book - synchronous
DOI: 10.1351/goldbook.S06219
Status: current

Definition
A concerted process in which the primitive change concerned (generally bond rupture and bond formation) have progressed to the same extent at the transition state is said to be synchronous. The term figuratively implies a more or less synchronized progress of the changes. However, the progress of the bonding change (or other primitive change) has not been defined quantitatively in terms of a single parameter applicable to different bonds or different bonding changes. The concept is therefore in general only qualitatively descriptive and does not admit an exact definition except in the case of concerted processes involving changes in two identical bonds.

Related Terms
- concerted process: https://goldbook.iupac.org/terms/view/C01234
- imbalance: https://goldbook.iupac.org/terms/view/I02945
- primitive change: https://goldbook.iupac.org/terms/view/P04845
- transition state: https://goldbook.iupac.org/terms/view/T06468

Source
- PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1170 (https://doi.org/10.1351/pac199466051077)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/S06219/html
- json: https://goldbook.iupac.org/terms/view/S06219/json
- xml: https://goldbook.iupac.org/terms/view/S06219/xml

Citation: Citation: 'synchronous' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.S06219
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Accessed: 2026-06-30T20:18:08+00:00