| abstract |
The dye base sulfate of formula (I) is produced with a residual amine content of less than 2000 ppm, as determined by HPLC, by precipitation of the dye base, by Friedel-Crafts alkylation, substitution and hydrolysis, as dye base sulfate and) take it in water and subject it to a first steam distillation, then filter and optionally dry at 50 to 180¦C, b) press cake or optionally dried dye base sulfate is treated with water it is moistened with water, c) it is subjected to steam distillation and additional filtration, and d) it is dried at about 50 to 180 ° C. |