Role of the nucleophilicity of the amino group of benzidines in the synthesis of hemiaminal ethers

•Synthesis of hemiaminal ethers from benzidines.•An unusual Mannich-type reaction of benzidines.•Amino nucleophilicity in hemiaminal ethers synthesis.•Mannich type reaction with alcohols. This paper presents a study of the reaction between some aromatic amines and formaldehyde in ethanol. Anisidines reacting with formaldehyde produced cyclic or linear aminals (hexahydrotriazines or methanediamines) whilst benzidines produced hemiaminal ethers (N,N′-bis(alkoxymethyl)benzidines) by reacting with formaldehyde, using alcohol as solvent. Condensed Fukui functions were calculated for the amines studied here, thereby enabling it to be established that the course of the reaction depends on the nucleophilicity of the amino functionality. [Display omitted]