{"term":{"id":"00129","title":"acyl species","longtitle":"IUPAC Gold Book - acyl species","doi":"10.1351\/goldbook.A00129","code":"A00129","status":"current","also defines":"<em>also defines<\/em>: acyl anion, acyl radical, acyl cation, acyl ion","definitions":[{"id":1,"text":"Acyl intermediates include acyl anions, acyl radicals and acyl cations (synonym acylium ions) which are formally derived from oxoacids $\\ce{R_{k}E(=O)_{l}(OH)_{m}}$ ($l \\neq 0$) by removal of a hydroxyl cation $\\ce{HO^{+}}$, a hydroxyl radical $\\ce{HO^{.}}$ or a hydroxyl anion $\\ce{HO^{-}}$, respectively, and replacement analogues of such intermediates. Acyl anions, radicals and cations can formally be represented by canonical forms having a negative charge, an unpaired electron or a positive charge on the acid-generating element of the oxoacid.Acyl anions, e.g. Acyl radicals, e.g. Acyl cations, e.g. ","links":[{"term":"acyl groups","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/A00123"},{"term":"anion","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/A00358"},{"term":"cation","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/C00907"},{"term":"intermediates","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/I03096"},{"term":"oxoacids","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/O04374"}],"sources":["PAC, 1993, 65, 1357. 'Revised nomenclature for radicals, ions, radical ions and related species (IUPAC Recommendations 1993)' on page 1357 (https:\/\/doi.org\/10.1351\/pac199365061357)","PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1312 (https:\/\/doi.org\/10.1351\/pac199567081307)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/A00129\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/A00129\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/A00129\/plain"},"citation":"Citation: 'acyl species' 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.A00129","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":"2026-05-06T17:21:59+00:00"}}