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Related to Safranine: Safranin o
any of a class of azine dyes. The simplest safra-nine is phenosafranine, with the structural formula
where R1 = NH2 and R2 = R3 = R4 = H. Phenosafranine is a red dye formed in small quantities upon the oxidation of a mixture of aniline and p-phenylenediamine. It has very few uses.
Tolusafranine, referred to commercially as safranine (R1 = NH2; R2 = R4 = CH3; R3 = H), is a bright red basic dye. It is formed upon the oxidation of a mixture of aniline, o-toluidine, and p-tolylenediamine. Tolusafranine was used until the 1940’s as a dye for leather, paper, and textiles. Today, it has been almost completely replaced by dyes that are less expensive and more colorfast.
Pinakryptol (R1 = R2 = R4 = H; R3 = NH2) is a green dye obtained by the action on o-aminodiphenylamine of, first, picryl chloride and second, zinc with hydrochloric acid. It is used as a desensitizer in photography for lowering the sensitivity of photographic plates. All safranines are toxic.
M. A. CHEKALIN