Usually, a "phenyl group" is synonymous with and is
represented by the symbol Ph (archaically,
Φ), or Ø. Benzene is sometimes denoted as PhH. Phenyl groups are generally attached to other atoms or groups. For example,
triphenylmethane () has three phenyl groups attached to the same carbon center. Many or even most phenyl compounds are not described with the term "phenyl". For example, the chloro derivative is normally called
chlorobenzene, although it could be called phenyl chloride. In special (and rare) cases, isolated phenyl groups are detected: the phenyl anion (), the phenyl cation (), and the phenyl
radical (). Although Ph and phenyl uniquely denote , substituted derivatives also are described using the phenyl terminology. For example, is nitrophenyl, and is pentafluorophenyl. Monosubstituted phenyl groups (that is, disubstituted benzenes) are associated with
electrophilic aromatic substitution reactions and the products follow the
arene substitution pattern. So, a given substituted phenyl compound has three isomers,
ortho (1,2-disubstitution),
meta (1,3-disubstitution) and
para (1,4-disubstitution). A disubstituted phenyl compound (trisubstituted benzene) may be, for example, 1,3,5-trisubstituted or 1,2,3-trisubstituted. Higher degrees of substitution, of which the pentafluorophenyl group is an example, exist and are named according to IUPAC nomenclature.
Etymology Phenyl is derived , which in turn derived , as the first phenyl compounds named were byproducts of
making and refining various
gases used for lighting. According to McMurry, "The word is derived , commemorating the discovery of benzene by
Michael Faraday in 1825 from the oily residue left by the illuminating gas used in London street lamps." ==Structure, bonding, and characterization==