| production method | 3-carboxy-1-(p-sulfophenyl)-5-pyrazolone, gamma acid and 2-hydroxy-5-methyl-4-(β-sulfated ethyl sulfone) aniline as starting materials. Gamma acid was first diazotized, coupled with 3-carboxyl -1-(p-sulfophenyl)-5-pyrazolone, 2-hydroxy-5-methyl-4-(β-sulfate ethyl sulfone) aniline is diazotized, a second coupling is carried out with the aforementioned coupling product, and then copper sulfate is added to complex the product. After salting out, filtration, drying to obtain the finished product.. |