-C₆H₅

where the six carbon atoms are arranged in a cyclic ring structure. This hydrophobic, highly stable and aromatic hydrocarbon unit can be found in many organic compounds. It can be thought of as being derived from benzene (C₆H₆). In fact, in chemical literature benzene itself is sometimes denoted as Ph. One of the simplest phenyl containing compounds is phenol, C₆H₅OH. The resonance stability of phenol makes it a stronger acid than that of aliphatic alcohols such as ethanol (pK_a = 10 vs. 16-18).

Presence of a phenyl group typically results in an ¹H-NMR shift around 7.7ppm.

Phenyl groups can also be found in polymers such as polystyrene.

The phenyl group belongs to the Aryl group of compounds.

The phenyl group differs from the benzyl functional group in that benzyls have an extra CH₂.