ArOAr

ArOAr is a general chemical notation used to denote a diaryl ether motif, in which two aryl groups are joined through an oxygen atom, giving the structure Ar–O–Ar′. The Ar groups may be identical (as in diphenyl ether) or different (for example, p-tolyl–O–phenyl). This motif appears across organic chemistry, materials science, and natural products.

Structural features of ArOAr linkages include an O–aryl–O framework that constrains rotation around the C–O bonds and influences the overall conformation and properties of the molecule. The diaryl ether bond is relatively robust to many conditions and can impact thermal stability and dielectric behavior. Variants with bulky or electron-rich or electron-poor aryl rings show a range of reactivities and physical properties.

ArOAr motifs occur in natural products, including certain lignans and other phenyl ether-containing compounds, as well as in synthetic materials. In polymer chemistry, diaryl ethers are key linkages in high-temperature polymers such as poly(arylene ether)s and related polyethers, where they contribute to thermal and mechanical performance. Diphenyl ether itself is a simple, well-studied diaryl ether used as a solvent and starting point for more complex materials.

Synthesis of ArOAr compounds is typically accomplished by O-arylation of phenols with aryl electrophiles under copper- or palladium-catalyzed conditions, such as Ullmann-type or Buchwald–Hartwig–type cross-couplings. Alternative routes include nucleophilic aromatic substitution on activated arenes or the use of diaryliodonium salts. The choice of method depends on the substrates and the desired substitution pattern on the aryl rings.

See also: diphenyl ether; poly(arylene ether) polymers; diaryl ether natural products.