Preparation
6,8-Bis(phenylamino)naphthalene-1-sulfonic acid?and 2,5-Diamino-4-methoxybenzenesulfonic acid condensation, and then product (add) ammonia in the cuprous oxide catalyst for the air oxidation.
Synthesis
Wool Fast Violet B 21, C.I. 50 325 [6837-46- 3], from 1,3-bis(phenylamino)naphthalene-8- sulfonic acid and 2-methoxy-1,4-phenylenediamine- 5-sulfonic acid proceeds differently. In the cyclization step the methoxyl group is split off as methanol. Therefore, the dye can also be synthesized from 1,4-phenylenediamine-2-sulfonic acid.
