05003 IUPAC Gold Book - quaternary ammonium compounds 10.1351/goldbook.Q05003 Q05003 current 1 Derivatives of ammonium compounds, $\ce{(NH4^{+})Y^{−}}$, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. Compounds having a carbon-nitrogen double bond (i.e. $\ce{R2C=N^{+}R2Y^{−}}$) are more accurately called iminium compounds. $\ce{[(CH3)4N]^{+}OH^{−}}$, tetramethylammonium hydroxide. ammonium compounds https://goldbook.iupac.org//terms/view/A00290 hydrocarbyl https://goldbook.iupac.org//terms/view/H02891 iminium compounds https://goldbook.iupac.org//terms/view/I02958 onium compounds https://goldbook.iupac.org//terms/view/O04291 PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1361 (https://doi.org/10.1351/pac199567081307) https://goldbook.iupac.org/terms/view/Q05003/html https://goldbook.iupac.org/terms/view/Q05003/json https://goldbook.iupac.org/terms/view/Q05003/plain Citation: 'quaternary ammonium compounds' 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.Q05003 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. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . 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. 2026-05-06T10:27:42+00:00