aryl group

aryl group (âr'ĭl), in chemistry, group of atoms derived from benzene or from a benzene derivative by removing one hydrogen that is bonded to the benzene ring (see radical). The simplest aryl group is phenyl, C₆H₅ ; it is derived from benzene. The tolyl group, CH₃C₆H₄, is derived from toluene (methylbenzene). The xylyl group, (CH₃)₂C₆H₃, is derived from xylene (dimethylbenzene). Just as several different alkyl groups may be derived from certain alkanes, so may several aryl groups be derived from certain aromatic compounds; for example, three different tolyl groups can be formed from toluene by removing hydrogen from different locations relative to the methyl group. When a functional group is joined with an aryl group, replacing the hydrogen that had been removed, a compound is formed whose characteristics depend largely on the functional group.