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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


An acyl group

An acyl group (IUPAC name: alkanoyl) is a functional group derived by the removal of one or more hydroxyl group from an oxoacid.[1]. In organic chemistry, the acyl group is usually derived from a carboxylic acid of the form RC O OH. It therefore has the formula RC(=O)-, with a double bond between the carbon and oxygen atoms (i.e. a carbonyl group), and a single bond between R and the carbon. Acyl groups can also be derived from other types of acids such as sulfonic acids, phosphonic acids, and some others.

Acyl halides can be used in Friedel-Crafts acylation to introduce the acyl moiety in an aromatic compound.

In biochemistry, Acyl-CoA is a derivate of fatty acid metabolism.


The names of acyl groups are typically derived from the corresponding acid by substituting the acid ending -ic with the ending -yl as shown in the table below. Note that methyl, ethyl, propyl, butyl etc. end in -yl are not acyl but alkyl groups, derived from alkanes.

Acyl group name
Corresponding carboxylic acid name
common systematic common systematic
formyl methanoyl formic acid methanoic acid
acetyl ethanoyl acetic acid ethanoic acid
propionyl propanoyl propionic acid propanoic acid
benzoyl benzoic acid
acryl propenoyl acrylic acid propenoic acid

Acyl species

In acyloxy groups the acyl group is bonded to oxygen: R-C=O-O-R' where R-C=O is the acyl group.

Acylium ions are cations of the type R-C+=O and play an important role as intermediates in organic reactions [1] for example the Hayashi rearrangement.


See also

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