A synthetic coal tar dye of the same composition (6,6'-dibromoindigo) as murex purple. Dibromoindigo was developed in 1904 causing the expensive natural product to became obsolete.
Synonyms and Related Terms
6,6'-dibromoindigo; CI 75800
Insoluble in organic solvents and water. Unaffected by alkalis. The color is lightfast except when exposed to nitric acid or chlorine bleaches.
- Helmut Schweppe, Schweppe color collection index and information book Comment: CI 75800, ammonia-sodium dithionite vat or sodium hydroxide-sodium dithionite vat