N-[p-(p-hydroxyanilino)phenyl]anthranilic acidin Sodium polysulfide solution in return 105 ~ 106 ° C heating 65 hours, then add salt from Sodium sulfide solution precipitation dye crude products, in the cold dilute Sodium hydroxide solution air oxidation. This Indophenolis by N-Phenylanthranilic acidand4-Nitrosophenolcondensation, product with Sodium hydrosulfide and reduction.
