Process for the purification of crude 3,4,3',4'-tetraaminodiphenyl
US4433168A · kind A · utility
3Cited by
11References
10Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Mar 22, 1982 |
| Grant date | Feb 21, 1984 |
| Priority date | — |
| Expiry date | Mar 22, 2002 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C209/84
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Crude 3,4,3',4'-tetraaminodiphenyl (TAD) prepared by ammonolysis of 3,3'-dichlorobenzidine in the presence of mainly Cu catalysts is purified by a process in which PA1 (a) after its isolation from the preparation process crude TAD is treated with an aqueous NH.sub.3 solution and, if desired, TAD thus treated is then PA1 (b) dissolved and reprecipitated in water in the presence of adsorbents and also of a water-soluble reducing agent. Compared with relevant processes of the state of the art, the process produces a higher yield of pure TAD and it is also simpler to carry out.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.