Acyl group
An acyl group 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.
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.[1]