Separation of 2,4-toluenediamine from an isomeric mixture of toluenediamines
US6469212B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 20, 2000 |
| Grant date | Oct 22, 2002 |
| Priority date | — |
| Expiry date | Mar 20, 2020 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C209/86
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A mixture comprised of about 60-85% of 2,4-toluenediamine (2,4-TDA) and about 15-40% of 2,6-toluenediamine (2,6-TDA) is melted, the temperature of the mixture is lowered to a 2,4-TDA nucleation temperature, and the temperature of the mixture is gradually reduced from the nucleation temperature to about 65 to about 70° C. The resultant mixture is in the form of a solids phase enriched in 2,4-TDA, and a novel and useful liquid phase enriched in 2,6-TDA. These phases are separated. Preferably the solids are further purified by “sweating” them and removing the sweated liquid impurities. The sweated liquid can be recycled together with another charge of a mixture comprised of 2,4-TDA and 2,6-TDA. 2,4-TDA can be produced with a purity of 96-99%.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.