Title: σ-adduct
Long Title: IUPAC Gold Book - σ-adduct
DOI: 10.1351/goldbook.A05436
Status: current

Definition
The product formed by the attachment of an electrophilic or nucleophilic entering group or of a radical to a ring carbon of an aromatic species so that a new $\ce{\upsigma\!\mbox{-}bond}$ is formed and the original conjugation is disrupted. (This has generally been called a '$\ce{\upsigma\!\mbox{-}complex}$', but adduct is more appropriate than complex according to the definitions given.) The term may also be used for analogous adducts to unsaturated (and conjugated) systems in general.

Related Terms
- Meisenheimer adduct: https://goldbook.iupac.org//terms/view/M03819
- adduct: https://goldbook.iupac.org//terms/view/A00138
- attachment: https://goldbook.iupac.org//terms/view/A00512
- conjugation: https://goldbook.iupac.org//terms/view/C01267
- electrophilic: https://goldbook.iupac.org//terms/view/E02021
- entering group: https://goldbook.iupac.org//terms/view/E02130
- nucleophilic: https://goldbook.iupac.org//terms/view/N04251
- radical: https://goldbook.iupac.org//terms/view/R05066

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/A05436/html
- json: https://goldbook.iupac.org/terms/view/A05436/json
- xml: https://goldbook.iupac.org/terms/view/A05436/xml

Citation: Citation: 'σ-adduct' 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.A05436
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Accessed: 2025-11-14T18:18:04+00:00