Term: Meisenheimer adduct
https://doi.org/10.1351/goldbook.M03819

Definition:
A cyclohexadienyl derivative formed as Lewis adduct from a nucleophile (Lewis base) and an aromatic or heteroaromatic compound, also called Jackson–Meisenheimer adducts. In earlier usage the term 'Meisenheimer complex' was restricted to the typical Meisenheimer alkoxide adducts of nitro-substituted aromatic ethers, e.g. M03819-1.png Analogous cationic adducts, such as: M03819-2.png considered to be reaction intermediates in electrophilic aromatic substitution reactions, are called 'Wheland intermediates', and sometimes, inappropriately, σ-complexes.

Related Terms:
1) σ-adduct (http://doi.org/10.1351/goldbook.A05436).
2) lewis adduct (http://doi.org/10.1351/goldbook.L03510).
3) lewis base (http://doi.org/10.1351/goldbook.L03511).
4) aromatic (http://doi.org/10.1351/goldbook.A00441).
5) adduct (http://doi.org/10.1351/goldbook.A00138).
6) reaction intermediates (http://doi.org/10.1351/goldbook.R05171).
7) electrophilic (http://doi.org/10.1351/goldbook.E02020).
8) substitution reactions (http://doi.org/10.1351/goldbook.S06078).
9) ethers (http://doi.org/10.1351/goldbook.E02221).

Images:
1) Not defined (https://goldbook.iupac.org/img/inline/M03819-1.png) 
2) Not defined (https://goldbook.iupac.org/img/inline/M03819-2.png) 

Source: PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1138 (https://doi.org/10.1351/pac199466051077)

Citation: 'Meisenheimer adduct' 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.M03819

License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.

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.