hydroxyphenylethyl

Hydroxyphenylethyl is a descriptive term used in organic chemistry to denote a hydroxy-substituted phenethyl moiety. It refers to a structure in which a phenyl ring bearing a hydroxyl group is connected through an ethyl linker (two carbon atoms) to another substituent or functional group. The hydroxy group on the ring can occupy the ortho, meta, or para position relative to the ethyl linkage, giving 2-, 3-, or 4-hydroxyphenethyl substructures.

As a common fragment in chemical nomenclature, hydroxyphenylethyl is not a single compound but a motif found in many molecules. Compounds with this motif include hydroxyphenethylamines, such as tyramine (4-hydroxyphenethylamine), which features a para-hydroxyphenethyl group attached to an amine. Dopamine is related, containing a 3,4-dihydroxyphenethyl backbone with additional functional groups. The hydroxyphenethyl fragment also appears in various natural products, pharmaceuticals, and fragrance-related molecules, where it contributes to aromaticity, hydrogen-bonding capacity, and lipophilicity.

Properties and applications vary with substitution pattern and the nature of the attached group. The presence of the phenolic OH increases polarity and enables hydrogen bonding, while the ethyl linker provides conformational flexibility. In medicinal chemistry and biochemistry, hydroxyphenylethyl motifs are explored as components of pharmacophores, targeted to interact with biological receptors or enzymes. In summary, hydroxyphenylethyl describes a versatile and widely used chemical motif rather than a specific compound.