Aryl group

In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl.

[1] "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used as a placeholder for the aryl group in chemical structure diagrams, analogous to “R” used for any organic substituent.

“Ar” is not to be confused with the elemental symbol for argon.

The simplest aryl group is phenyl, which is made up of a benzene ring with one of its hydrogen atom replaced by some substituent, and has the molecular formula C6H5−.

In this case, if the phenyl group were taken to be the parent hydrocarbon, the compound would be named hydroxybenzene.