Acyl Group Definition and Examples

Learn What an Acyl Group Is in Chemistry

Acyl Group Chemical Structure
Acyl Group Chemical Structure.

Organic chemistry defines several moieties or functional groups. The acyl group is one of them:

Acyl Group Definition

An acyl group is a functional group with formula RCO- where R is bound to the carbon atom with a single bond. Typically the acyl group is attached to a larger molecule such that the carbon and oxygen atoms are joined by a double bond.

Acyl groups are formed when one or more hydroxyl groups are removed from an oxoacid.

Even though acyl groups are almost exclusively discussed in organic chemistry, they may be derived from inorganic compounds, such as phosphonic acid and sulfonic acid.

Acyl Group Examples

Esters, ketones, aldehydes and amides all contain the acyl group. Specific examples include acetyl chloride (CH3COCl) and benzoyl chloride (C6H5COCl).


  • IUPAC (1997). Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). "Acyl groups". doi:10.1351/goldbook.A00123
  • Smith, Michael B. (2013). March's Advanced Organic Chemistry. Hoboken, NJ: Wiley. p. 857. ISBN 978-0-470-46259-1.
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Helmenstine, Anne Marie, Ph.D. "Acyl Group Definition and Examples." ThoughtCo, Aug. 27, 2020, Helmenstine, Anne Marie, Ph.D. (2020, August 27). Acyl Group Definition and Examples. Retrieved from Helmenstine, Anne Marie, Ph.D. "Acyl Group Definition and Examples." ThoughtCo. (accessed May 31, 2023).