ArNR2

ArNR2 denotes a class of tertiary arylamines in which an aryl group (Ar) is bonded to a nitrogen atom bearing two substituents R and R'. The general structure is Ar–N(R)2. Examples include N,N-dimethylaniline (Ar = phenyl, R = Me), N,N-diethylaniline, and various N,N-diaryl derivatives. This distinguishes ArNR2 from primary and secondary arylamines, which contain N–H bonds.

The lone pair on nitrogen in ArNR2 is partially delocalized into the adjacent aryl ring, which often makes these compounds less basic than aliphatic tertiary amines. Basicity can be modulated by the nature of the N-substituents (R) and by substituents on the Ar ring; bulky groups can also affect planarity and resonance with the ring, altering reactivity and steric profile. ArNR2 compounds are typically more nucleophilic at nitrogen than many other aryl-derived motifs, but their nucleophilicity is also influenced by conjugation with the aryl system.

Synthesis of ArNR2 generally proceeds by alkylation or arylation of a secondary arylamine (ArNHR) or via direct C–N coupling methods. Common routes include N-alkylation or N-arylation of ArNH2 followed by further substitution, or palladium- or nickel-catalyzed Buchwald–Hartwig amination to form Ar–N(R)2 from an aryl halide and a secondary amine.

Applications of ArNR2 span coordination chemistry and materials science. Triarylarylamines (Ar3N) are widely used as hole-transport materials in organic electronics, while other ArNR2 derivatives serve as intermediates in pharmaceutical synthesis and as ligands in metal-catalyzed processes.

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