For separating 1,5- and 1,8-dihydroxyanthraquinone from one another or for removing impurities from 1,5- or 1,8-dihydroxyanthraquinone, the fact is used that a) 1,5-dihydroxyanthraquinone is hardly soluble in an aqueous alkali metal hydroxide solution at a low alkali metal hydroxide concentration, but goes into solution as a salt at higher alkali metal hydroxide concentration and b) 1,8-dihydroxyanthraquinone is soluble in an aqueous alkali metal hydroxide solution at a low alkali metal hydroxide concentration, but is precipitated as a salt at a higher alkali metal hydroxide concentration. The 1,5- and 1,8-dihydroxyanthraquinones are suitable as intermediates for the preparation of dyestuffs.
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