Process for the preparation of a dyestuff consisting substantially of only unsymmetrical 1:2-chromium complex azo dyestuffs
US3939140A · kind A · utility
7Cited by
10References
15Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 17, 1974 |
| Grant date | Feb 17, 1976 |
| Priority date | — |
| Expiry date | Jun 17, 1994 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09B45/16
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
Process for preparing a dyestuff consisting essentially of only unsymmetrical 1:2-chromium complex azo dyestuffs by heating a mixture of o,o'-dihydroxy azo dyestuffs and o-carboxy-o'-hydroxy azo dyestuffs, both being free from sulfonic acid groups, with chromium-III chloride in an organic solvent at a temperature of 105.degree. to 120.degree.C until the portion of o,o'-dihydroxy azo dyestuff is completely metallized and completing the 1:2-chromium complex formation by adjusting the pH-value to 5.0-6.5, and heating at a temperature of 70.degree. to 90.degree.C.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.