By reaction of aromatic aldehydes with ammonium acetate a series of 1,2-diaryl-1,2-diamino-ethanes and their derivatives was obtained. The mechanism of reaction was suggested and its principal stages were proved. Reactions with ammonium acetate of aromatic aldehydes containing ortho-substituents resulted in the corresponding 2,4,5-triaryl-4,5-dihydroimidazoles.