Title: betaines
Long Title: IUPAC Gold Book - betaines
DOI: 10.1351/goldbook.B00637
Status: current

Definition
Originally, the compound betaine, $\ce{(CH3)3N^{+}–CH2C(=O)O^{−}}$ $N,N,N$-trimethylammonioacetate, and similar zwitterionic compounds derived from other amino acids. By extension, neutral molecules having charge-separated forms with an onium atom which bears no hydrogen atoms and that is not adjacent to the anionic atom. Betaines cannot be represented without formal charges. E.g.  

Related Terms
- dipolar compounds: https://goldbook.iupac.org//terms/view/D01753
- mesoionic compounds: https://goldbook.iupac.org//terms/view/M03842
- onium: https://goldbook.iupac.org//terms/view/O04291
- ylides: https://goldbook.iupac.org//terms/view/Y06728
- zwitterionic compounds: https://goldbook.iupac.org//terms/view/Z06752

Source
- PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1322 (https://doi.org/10.1351/pac199567081307)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/B00637/html
- json: https://goldbook.iupac.org/terms/view/B00637/json
- xml: https://goldbook.iupac.org/terms/view/B00637/xml

Citation: Citation: 'betaines' 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.B00637
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Accessed: 2026-05-06T14:12:58+00:00