text: 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. "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.
  A simple aryl group is phenyl (), a group derived from benzene. Examples of other aryl groups consist of:
  * The tolyl group () which is derived from toluene (methylbenzene)
  * The xylyl group (), which is derived from xylene (dimethylbenzene)
  * The naphthyl group (), which is derived from naphthalene
  Arylation is the process in which an aryl group is attached to a substituent. It is typically achieved by cross-coupling reactions.