Term: quaternary ammonium compounds
https://doi.org/10.1351/goldbook.Q05003

Definition:
Derivatives of ammonium compounds, (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. R2C=N+R2Y−) are more accurately called iminium compounds. e.g. [(CH3)4N]+OH−, tetramethylammonium hydroxide.

Related Terms:
1) ammonium compounds (http://doi.org/10.1351/goldbook.A00290).
2) hydrocarbyl (http://doi.org/10.1351/goldbook.H02891).
3) iminium compounds (http://doi.org/10.1351/goldbook.I02958).
4) onium compounds (http://doi.org/10.1351/goldbook.O04291).

Source: 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)

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. https://doi.org/10.1351/goldbook.Q05003

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