117-14-6

Moderately toxic by ingestion.When heated to decomposition it emits toxic fumes ofSOx.

Anthraquinone-1,5-disulfonic acid , Thiol Acid, and anthraquinone- 1,8-disulfonic acid , Azine Acid, are produced by disulfonation under conditions similar to those for monosulfonation except for an increased concentration of SO3 . After sulfonation of the anthraquinone is complete, the 1,5-acid is precipitated by slow addition of dilute sulfuric acid, collected, and washed with dilute sulfuric acid. The filter cake is dissolved in hot water, the solution treated with charcoal, and the anthraquinone- 1,5-disulfonic acid precipitated from the filtrate as its disodium salt by addition of saturated sodium chloride solution. The 1,8-acid is isolated as the potassium salt from the sulfuric acid mother liquors and the wash acids (see also and ). Mercury can be removed in a similar manner as given for anthraquinone-1- sulfonic acid (see, e.g., ).