New fuchsine is an organic compound with the formula [(H<sub>2</sub>N(CH<sub>3</sub>)C<sub>6</sub>H<sub>3</sub>)<sub>3</sub>C]Cl. It is a green-colored solid that is used as a dye of the triarylmethane class. It is one of the four components of basic fuchsine, and one of the two that are available as single dyes.[1] The other is pararosaniline. It is prepared by condensation of ortho-toluidine with formaldehyde. This process initially gives the benzhydrol 4,4'-bis(dimethylamino)benzhydrol, which is further condensed to give the leuco (colorless) tertiary alcohol [(H<sub>2</sub>N(CH<sub>3</sub>)C<sub>6</sub>H<sub>3</sub>)<sub>3</sub>COH, which is oxidized in acid to give the dye.<ref>{{cite book|doi=10.1002/0471238961.2018091620080520.a01.pub2|chapter=Triphenylmethane and Related Dyes|title=Kirk-Othmer Encyclopedia of Chemical Technology|year=2013|last1=Thetford|first1=Dean|last2=Updated By Staff|isbn=978-0471238966}}</ref> ==Use as dye and stain== New fuchsine is used to dye [[polyacrylonitrile]], paper, and leather. In biology, it can be used for staining acid-fast organisms, e.g. by Ziehl–Neelsen stain, and for making Schiff's reagent. As a primary amine, the dye can be diazotized in the laboratory, and the resulting diazonium salt used as a trapping agent in enzyme histochemistry.[2]
The name fuchsine recognizes Leonhart Fuchs.