| production method | prepared by sulfonation of 1, 4-dihydroxyanthraquinone. To the reaction vessel was added 5000L of water and heated to 50 °c, and 200kg of 1, 4-dihydroxyanthraquinone, 420kg of sodium bisulfite, 105kg of boric acid and 126kg of manganese dioxide were added. The temperature was then raised to 95-98 °c in 2H and the reaction was maintained at this temperature for 4-5H. The reaction was added to 600L of hydrochloric acid, cooled to 45 ° C. And filtered. The filter cake was washed with dilute hydrochloric acid (20L hydrochloric acid in 1000L water) and dried to give 1, 4-dihydroxyanthraquinone -2-sulfonic acid, which is needle-like crystal, in dilute alkali solution first red-purple, then blue. |
