| 摘要 |
<p>A process for the preparation of a concentrated storage-stable aqueous solution of the dyestuff of the formula <IMAGE> (I) is characterized in that the reaction mixture obtainable from the quinone derivative of the formula <IMAGE> (II) by sulphation and subsequent oxidation cyclization, preferably with ammonium, sodium or potassium peroxodisulphate, in oleum is diluted with water or sulphuric acid to a sulphuric acid concentration of 37-50%, preferably 41-43%, and the product which thereby precipitates is separated off and brought to a pH of about 2-6, preferably 3-4, in water with basic lithium compounds, preferably lithium carbonate or lithium hydroxide.</p> |
