Title: addition reaction
Long Title: IUPAC Gold Book - addition reaction
DOI: 10.1351/goldbook.A00133
Status: current

Definition
A chemical reaction of two or more reacting molecular entities, resulting in a single reaction product containing all atoms of all components, with formation of two chemical bonds and a net reduction in bond multiplicity in at least one of the reactants. The reverse process is called an elimination reaction. The addition may occur at only one site (α-addition, 1/1/addition), at two adjacent sites (1/2/addition) or at two non-adjacent sites (1/3/- or 1/4/addition, etc.). For example:   If the reagent or the source of the addends of an addition are not specified, then it is called an addition transformation.

Related Terms
- addition: https://goldbook.iupac.org//terms/view/A00132
- cheletropic reaction: https://goldbook.iupac.org//terms/view/C01014
- chemical reaction: https://goldbook.iupac.org//terms/view/C01033
- cycloaddition: https://goldbook.iupac.org//terms/view/C01496
- elimination: https://goldbook.iupac.org//terms/view/E02038
- molecular: https://goldbook.iupac.org//terms/view/M03986
- reagent: https://goldbook.iupac.org//terms/view/R05190
- transformation: https://goldbook.iupac.org//terms/view/T06446
- α-addition: https://goldbook.iupac.org//terms/view/A00001

Source
- PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1081 (https://doi.org/10.1351/pac199466051077)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/A00133/html
- json: https://goldbook.iupac.org/terms/view/A00133/json
- xml: https://goldbook.iupac.org/terms/view/A00133/xml

Citation: Citation: 'addition reaction' 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.A00133
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Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.
Accessed: 2026-07-14T03:46:21+00:00