Title: spiro union
Long Title: IUPAC Gold Book - spiro union
DOI: 10.1351/goldbook.S05884
Status: current

Definition
A union formed by a single atom which is the only common member of two rings. The common atom is designated as the spiro atom. A free spiro union is one which constitutes the only union direct or indirect between the two rings.

Source
- Blue Book, p. 37 (https://www.acdlabs.com/iupac/nomenclature/)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/S05884/html
- json: https://goldbook.iupac.org/terms/view/S05884/json
- xml: https://goldbook.iupac.org/terms/view/S05884/xml

Citation: Citation: 'spiro union' 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.S05884
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.
Collection: If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .
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: 2026-04-22T10:48:00+00:00