Rosaniline (triamido diphenyl tolyl carbinol) C20H21N3O, a methyl derivative of triamidotriphenylkarbinol or pararosaniline.

Rosaniline is formed when a mixture of equal molecules of orthotoluidine, paratoluidine and aniline is oxidized; pure aniline and pure toluidine do not provide rosaniline. It forms colourless crystals, is difficult to dissolve in water and ether, more easily in alcohol, turns reddish in air and emits ammonia and aniline when heated, or leuco compounds in conjunction with reducing agents. Rosaniline is a triacidic base, its salts mixed with 1 equivalent of acid are red with a metallic sheen and dissolve in water and alcohol to an intense red colour. The brown triacidic salts are more soluble and easily decomposed by water. In addition to rosaniline, oxidation of the crude aniline oil also forms pararosaniline (triamidotriphenylcarbinol) (C6H4.NH2)3.C(OH), which exhibits great similarity with rosaniline in all its compounds. Salts of rosaniline and pararosaniline and of the alkylated bases are widely used as dyes. The hydrochloric acid salt C20H19N3.HCI+4H2O is commercially available as Fuchsine (Ruby, Magenta, Aniline Red, Rosein), but acetate is also known by the same name, and these dyes always contain some parafuchsin.

Source: Meyers Großes Konversations-Lexikon, 6. Auflage 1905–1909