Acyl

An acyl group (IUPAC name: alkanoyl) is a functional group derived by the removal of one or more hydroxyl group from an oxoacid.. 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 CoAs are derivates of fatty acid metabolism, with acetyl CoA as an example. They are actually thiol esters.

Examples

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 (R-CO-)		Corresponding carboxylic acid name (R-CO-OH)
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 for example the Hayashi rearrangement.

References

See also

• Acylation