Term: esters https://doi.org/10.1351/goldbook.E02219 Definition: Compounds formally derived from an oxoacid RkE(=O)l(OH)m, (l ≠ 0) and an alcohol, phenol, heteroarenol, or enol by linking with formal loss of water from an acidic hydroxy group of the former and a hydroxy group of the latter. By extension acyl derivatives of alcohols, etc. Acyl derivatives of chalcogen analogues of alcohols (thiols, selenols, tellurols) etc. are included. E.g. R'C(=O)(OR), R'C(=S)(OR), R'C(=O)(SR), R'S(=O)2(OR), (HO)2P(=O)(OR), (R'S)2C(=O), ROCN (but not R–NCO) (R ≠ H). Note: O-Alkyl derivatives of other acidic compounds [see @A00266@] may be named as esters but do not belong to the class esters proper. E.g. (Ph)2POCH3 methyl diphenylphosphinite. Related Terms: 1) acylals (http://doi.org/10.1351/goldbook.A00119). 2) ortho esters (http://doi.org/10.1351/goldbook.O04334). 3) depsides (http://doi.org/10.1351/goldbook.D01603). 4) depsipeptides (http://doi.org/10.1351/goldbook.D01604). 5) glycerides (http://doi.org/10.1351/goldbook.G02647). 6) lactides (http://doi.org/10.1351/goldbook.L03436). 7) lactones (http://doi.org/10.1351/goldbook.L03439). 8) macrolides (http://doi.org/10.1351/goldbook.M03663). 9) amides (1) (http://doi.org/10.1351/goldbook.A00266). 10) oxoacid (http://doi.org/10.1351/goldbook.O04374). 11) acyl (http://doi.org/10.1351/goldbook.A00123). 12) alcohols (http://doi.org/10.1351/goldbook.A00204). 13) thiols (http://doi.org/10.1351/goldbook.T06359). 14) selenols (http://doi.org/10.1351/goldbook.S05574). Source: PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1334 (https://doi.org/10.1351/pac199567081307) Citation: 'esters' 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.E02219 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.