Term: intermediate
https://doi.org/10.1351/goldbook.I03096

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:
1) molecular entity (http://doi.org/10.1351/goldbook.M03986).
2) lifetime (http://doi.org/10.1351/goldbook.L03515).
3) chemical reaction (http://doi.org/10.1351/goldbook.C01033).
4) chemical species (http://doi.org/10.1351/goldbook.CT01038).
5) elementary reaction (http://doi.org/10.1351/goldbook.E02035).
6) reaction step (http://doi.org/10.1351/goldbook.R05178).
7) stepwise reaction (http://doi.org/10.1351/goldbook.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)

Citation: 'intermediate' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.I03096

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