Purification of photographic image-forming sulfonamido compounds employing immiscible solvents
US4228070A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 28, 1979 |
| Grant date | Oct 14, 1980 |
| Priority date | — |
| Expiry date | Feb 28, 1999 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09B29/28
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
A process for purifying a photographic image-forming sulfonamido compound comprises the steps of: PA1 a. preparing a first solution by dissolving an unpurified image-forming sulfonamido compound in an aprotic solvent; PA1 b. removing impurities from said first solution by, at least once: PA2 i. mixing said first solution with an immiscible nonpolar, low-boiling organic solvent to form a mixture of said first solution and a second solution comprising said immiscible nonpolar, low-boiling organic solvent and at least a portion of said impurities; and PA2 ii. separating said first solution from said second solution; and PA1 c. recovering purified image-forming sulfonamido compound from said first solution. The process is useful in the purification of a nondiffusible sulfonamido compound which is alkali-cleavable upon oxidation to release a diffusible sulfonamido color-providing moiety.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.