C.I. Vat Blue 43

3-(4-Hydroxyanilino)carbazole in 107 ℃ in Butanol sodium polysulfide solution reflux heating 24 hours, and then with sodium nitrite short time heating, steam out of Butanol, through the air and add salt to make dye completely precipitated out. This indophenol is by carbazole and nitroso phenol in concentrated sulfuric acid in – 20 to 23 ℃ condensation, then reduction and have to (BIOS983, 71 -74). To cure solution is to add 3 – methyl – 4 ‘- hydroxy – 4 -aminodiphenylamine, 4, 4’ – dihydroxydiphenyl aniline and phenol , improved the performance of the dye (BIOS983, 75- 81). Note: use with C.I. leuco sulfur dye similar method, some the structure of the dyes can be converted into the leuco compound.