production method | with reducing brilliant purple RR as raw material, after esterification, neutralization and evaporation of solvent, insoluble matters were removed by filtration. The filtrate was subjected to salting-out, filtration, drying and pulverization to obtain a finished product.. 76ml of pyridine (anhydrous) was added to the reaction vessel, 13.5g of chlorosulfonic acid (industrial product) was added at 20 ° C., a mixture of 10g of reductive brilliant violet RR (97%) and 10g of iron powder was added at 35-40 ° C., and the temperature was raised to 50-55 ° C. For 3-5 hours. After completion of the reaction, the reaction solution was poured into an aqueous sodium carbonate solution, and pyridine was recovered by distillation. Filter while hot. Salt was added to the filtrate for salting out and filtration to obtain the product. |