Pararosaniline, pararosaniline free base, Basic Red 9, or C.I. 42500 is an organic compound with the formula . It is the free base form of pararosaniline hydrochloride, , a magenta solid with a variety of uses as a dye.Thomas Gessner and Udo Mayer "Triarylmethane and Diarylmethane Dyes" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. It is one of the four components of basic fuchsine.Horobin RW, Kiernan JA (2002) Conn's Biological Stains, 10th ed. Oxford: BIOS. It is structurally related to other triarylmethane dyes called methyl violets (e.g. crystal violet) which feature methyl groups on nitrogen.
It is prepared by the condensation of aniline and . Alternatively, it arises from the oxidation of 4,4'-bis(aminophenyl)methane in the presence of aniline.
Uses It is used to dye polyacrylonitrile fibers. It is used to detect sulfur dioxide. Pararosaniline is used as a colorimetric test for aldehydes, in the Schiff test. It is the only basic fuchsine component suitable for making the aldehyde-fuchsine stain for pancreatic islet beta cells. It has use as an antischistosomal.
Related compounds 4,4'-Thiodianiline 4,4'-Methylenedianiline 4,4'-Oxydianiline Dapsone
References
Further reading . .