6362-18-1

4,5-Diaminonaphthalene-1-sulfonic acid is used as an intermediate for 4,5-dihydroxynaphthalene-1-sulfonic acid and perimidine derivatives.

1-Nitronaphthalene is sulfonated with oleum at 20℃, and the sulfonation mass is nitrated at 35℃. After quenching and liming out, the liquors are reduced with iron powder under slightly acidic conditions. After removal of iron residues, the product 4,5-diamino-1-naphthalenesulfonic acid is isolated in 40 % yield by acidifying and salting.