Process for purification of crude 4,4'-diamino-1,1'-dianthraquinonyl-3,3'-disulfonic acids and salts thereof
US5393899A · kind A · utility
1Cited by
5References
12Claims
0Family size
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Key dates
| Filing date | Aug 19, 1993 |
| Grant date | Feb 28, 1995 |
| Priority date | — |
| Expiry date | Aug 19, 2013 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C2603/24
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.