The constitution of the fuchsine bases (pararosaniline and rosaniline) was determined by E.
Rosenstiehl (Jahres., 1869, p. 693) found also that different rosanilines were obtained according to whether orthoor para-toluidine was oxidized with aniline; and he gave the name rosaniline to the one obtained from aniline and ortho-toluidine, reserving the term pararosaniline for the other.
A similar series of reactions was carried out with rosaniline, which was shown to be the corresponding derivative of tolyldiphenylmethane.
The free pararosaniline, C19H19N30, and rosaniline, C20H21N30, may be obtained by precipitating solutions of their salts with a caustic alkali, colourless precipitates being obtained, which crystallize from hot water in the form of needles or plates.
Fuming nitric acid gives a paratrinitro substitution derivative which on reduction gives paraleucaniline; the salt of the carbinol formed on oxidizing this substance is the valuable dye rosaniline.