Acyl group

The acetyl group, the acyl group related to acetic acid.

Drawing of acetic acid showing two carbon atoms. The drawing, is one kind of structural formula.

In chemistry, an acyl group is a functional group (part of a molecule) related to an oxoacid. Removing a −OH group from an oxoacid gives the related acyl group.

In organic chemistry, acyl groups are usually related to carboxylic acids. For example, acetic acid is a carboxylic acid with the formula CH₃COOH, and the acetyl group is an acyl group with the formula CH₃CO−.

The formal definition of an acyl group allows for inorganic acids. The nitro group (related to nitric acid) and sulfonyl group (related to sulfuric acid and sulfonic acids) are inorganic acyl groups by this definition.