Term: addition reaction
https://doi.org/10.1351/goldbook.A00133

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: A00133-1.png A00133-2.png If the reagent or the source of the addends of an addition are not specified, then it is called an addition transformation.

Related Terms:
1) addition (http://doi.org/10.1351/goldbook.A00132).
2) α-addition (http://doi.org/10.1351/goldbook.A00001).
3) cheletropic reaction (http://doi.org/10.1351/goldbook.C01014).
4) cycloaddition (http://doi.org/10.1351/goldbook.C01496).
5) chemical reaction (http://doi.org/10.1351/goldbook.C01033).
6) molecular (http://doi.org/10.1351/goldbook.M03986).
7) elimination (http://doi.org/10.1351/goldbook.E02038).
8) reagent (http://doi.org/10.1351/goldbook.R05190).
9) transformation (http://doi.org/10.1351/goldbook.T06446).

Images:
1) Not defined (https://goldbook.iupac.org/img/inline/A00133-1.png) 
2) Not defined (https://goldbook.iupac.org/img/inline/A00133-2.png) 

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)

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. https://doi.org/10.1351/goldbook.A00133

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