NNdialkylated

N,N-dialkylated, written as N,N-dialkylated, is a term used in organic chemistry to describe a nitrogen atom that bears two alkyl substituents. In common usage, this refers to the outcome of N,N-dialkylation of an amine, where two alkyl groups are introduced onto the same nitrogen. The resulting species are typically tertiary amines (RNR'2), in which the nitrogen has three carbon substituents and no N–H bonds. The concept also applies to amides, yielding N,N-dialkylated amide nitrogens (R-CO-NR'2), though this alters reactivity and properties relative to secondary or primary amides.

Synthesis and scope: N,N-dialkylation is usually accomplished by alkylating a primary amine (RNH2) or a secondary amine (R2NH) with alkyl halides or sulfonates, often in the presence of a base. The reaction can proceed in one or two steps, with care taken to avoid over-alkylation that forms quaternary ammonium salts (R4N+ X−). Steric hindrance and substrate electronics influence reactivity and selectivity. Reductive or catalytic methods can also achieve N,N-dialkylation under milder conditions or with greater control.

Examples and applications: Notable N,N-dialkylated amines include N,N-dialkylanilines such as N,N-dimethylaniline and related aryl-NR2 compounds, as well as aliphatic tertiary amines like tri-substituted amines formed via N,N-dialkylation of primary amines. These compounds are widely used as bases, ligands in metal catalysis, and pharmacophores in medicinal chemistry due to their basicity, lipophilicity, and ability to participate in hydrogen-bonding and coordination interactions.

See also: amines, N-alkylation, tertiary amine, quaternary ammonium salts.