Purification process for MDA
US4029705A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 18, 1975 |
| Grant date | Jun 14, 1977 |
| Priority date | — |
| Expiry date | Aug 18, 1995 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C211/50
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process is described for the selective removal of 2,2'- and 2,4'-diaminodiphenylmethanes from mixtures containing 2,2'-, 2,4'- and 4,4'-diaminodiphenylmethanes and polyamines by heating these mixtures in the presence of aqueous hydrochloric acid (55 to 95 percent by equivalents based on the total amine in the starting material) and formaldehyde. The process is particularly useful to facilitate the isolation of substantially pure 4,4'-isomer from aniline-formaldehyde condensation products. The pure 4,4'-isomer is a valuable intermediate for polyamides as well as for the corresponding diisocyanate. The by-products of the reaction are oligomeric polymethylene polyphenyl polyamines which are also useful as curing agents and intermediates for polymethylene polyphenyl polyisocyanates and the like.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.