2014 Volume 22 Pages 57-63
6,6'-Dibromoindigo is a major component of the historic pigment ancient purple, also known as Tyrian purple, royal purple, or shellfish purple. Arguably, it is not only the oldest known pigment but also the most expensive and best known. The indigo parent of 6,6'-Dibromoindigo was the subject of the first chemical industry and is now used broadly as a commercial product. We have already synthesized it by referring to the paper by Imming P. et al. 2001, Synth Commun 31:3721-27' and have examined its reduction and dyeing qualities, but to our knowledge its color fastness has never been measured. Tests of the color fastness of this dye consisted of xenon lamp irradiation, rubbing, washing, and perspiration permeation. The fastness of ancient purple was almost the same as, or slightly better than, that of indigo. We concluded that ancient purple has good color fastness after dyeing.