phenyl

Phenyl is a functional group derived from benzene by removing one hydrogen atom. It is the aryl substituent with the formula C6H5-, commonly abbreviated Ph- in chemical notation. The phenyl group is widely used to denote a phenyl substituent in molecules ranging from simple organics to complex pharmaceuticals and polymers.

Structurally, the phenyl group consists of a planar, six-membered benzene ring attached to the rest of the molecule at one carbon. That attachment carbon is sp2-hybridized, and the ring maintains aromatic stabilization through delocalized pi electrons. The group is largely nonpolar and hydrophobic, contributing aromatic character to the molecules it inhabits.

In naming and representation, Ph- is the standard shorthand for the phenyl substituent. The neutral radical form is C6H5•, and the substituent itself is often written as C6H5-. The phenyl unit has a nominal molar mass of 77.11 g/mol. Phenyl should not be confused with the related benzyl group, which is C6H5CH2-.

Reactivity and applications: The phenyl group is a common aryl substituent installed in organic synthesis via cross-coupling techniques such as Suzuki, Heck, and Sonogashira reactions, typically using phenyl halides or phenyl boronic acids. It can be introduced by attaching a phenyl group to a substrate, or via formation of phenyl ethers or phenyl esters for protecting group strategies. In materials chemistry, phenyl rings are key components of polymers like polystyrene and appear in various dyes and pharmaceuticals, where they provide stability and aromatic character.