Title: intermediate
Long Title: IUPAC Gold Book - intermediate
DOI: 10.1351/goldbook.I03096
Status: current

Definition
A molecular entity with a lifetime appreciably longer than a molecular vibration (corresponding to a local potential energy minimum of depth greater than \(R\ T\)) that is formed (directly or indirectly) from the reactants and reacts further to give (either directly or indirectly) the products of a chemical reaction; also the corresponding chemical species.

Related Terms
- chemical reaction: https://goldbook.iupac.org//terms/view/C01033
- chemical species: https://goldbook.iupac.org//terms/view/CT01038
- elementary reaction: https://goldbook.iupac.org//terms/view/E02035
- lifetime: https://goldbook.iupac.org//terms/view/L03515
- molecular entity: https://goldbook.iupac.org//terms/view/M03986
- reaction step: https://goldbook.iupac.org//terms/view/R05178
- stepwise reaction: https://goldbook.iupac.org//terms/view/S05970

Source
- PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1126 (https://doi.org/10.1351/pac199466051077)

Related Reference
- PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 170 (https://doi.org/10.1351/pac199668010149)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/I03096/html
- json: https://goldbook.iupac.org/terms/view/I03096/json
- xml: https://goldbook.iupac.org/terms/view/I03096/xml

Citation: Citation: 'intermediate' 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.I03096
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Accessed: 2026-05-31T01:45:48+00:00