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Thiocarmin R is an acid wool dye from the series of diaminophenothiazine dyes.

Thiocarmin R has been prepared, analogously to Lauth’sViolet, by oxi dation of 4-amino-N-ethyl-N-benzylaniline-3 sulfonic acid in the presence of hydrogen sulfide and zinc chloride. In this case, too, better yields are obtained by using the thiosulfate method. According to the same preparation route, the thioninedisulfonic acid is obtained from 2,5 diaminobenzenesulfonic acid and 2-aminoben-zenesulfonic acid.