| abstract |
In a process for producing 8-amino-1-naphthol-3,6-disulfonic acid which comprises subjecting a 1-nitronaphthalene-3,6,8-trisulfonic acid reaction mixture to reduction, subjecting the resulting 1-naphthylamine-3,6,8-trisulfonic acid salt mixture to alkali fusion and subjecting the alkali fusion mixture to precipitation by mixing with an acid to obtain 8-amino-1-naphthol-3,6-disulfonic acid as a partial alkali metal salt, the amount of acids and bases used can be curtailed and the quality of the product can be improved by performing the precipitation by mixing said alkali fusion mixture with said 1-nitronaphthalene-3,6,8-trisulfonic acid reaction mixture, separating the precipitated partial alkali metal salt of 8-amino-1-naphthol-3,6-disulfonic acid by filtration, and using as a starting material for said reduction reaction the resulting filtrate containing 1-nitronaphthalene-3,6,8-trisulfonic acid and/or a salt thereof. |