Process for purification of crude 4,4'-diamino-1,1'-dianthraquinonyl-3,3'-disulfonic acids and salts thereof
AssigneeSumimoto Chemical Company, Limited
InventorsHiroki Inoue, Iwao Sakaguchi, Katsutoshi Numano, Toshiaki Kishimoto, Yoshiaki Hayashi, Keisuke Ito
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Abstract
Crude 4,4'-diamino-l,l'-dianthraquinonyl-3,3'-disulfonic acids or salts thereof are purified by subjecting an aqueous solution containing the crude products to salting-out using inorganic salts, the aqueous solution being adjusted within a range of from acid to neutral region, whereby a product usable as such for the production of 4,4'-diamino-1,1'-dianthraquinonyl red pigments having excellent pigmentary properties is obtained in high yields with industrial advantages.
Claims12
A process for preparation of disulfonic acid intermediates of 4,4'-diamino-1,1'-dianthraquinonyl red pigments from a crude 4,4'-diamino-1,1'-dianthraquinonyl-3,3'-disulfonic acid or salt thereof, which comprises mixing an inorganic salt with an aqueous solution containing the crude disulphonic acid or the salt thereof to effect salting-out, the aqueous solution being adjusted to an acidic pH after or before the mixing.
A process for producing a 4,4'-diamino1,1'-dianthraquinonyl-3,3'-disulfonic acid or a salt thereof, which comprises preparing an aqueous solution containing a crude 4,4'-diamino-1,1'-dianthraquinonyl-3,3'-disulfonic acid or a salt thereof, and mixing an inorganic salt with the aqueous solution to effect salting-out, the aqueous solution being adjusted to an acidic PH after or before the mixing of the inorganic salt with the aqueous solution, whereby a 4,4'-diamino-1,1'-dianthraquinonyl-3,3'-disulfonic acid or a salt thereof useful as such for production of a 4,4'-diamino-1,1'-dianthraquinonyl red pigment is produced.
Dependencies are inferred from the claim text.