Method for producing an aromatic dianhydride
US11787776B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 4, 2019 |
| Grant date | Oct 17, 2023 |
| Priority date | — |
| Expiry date | Jun 29, 2040 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D407/12
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A method for producing an aromatic dianhydride includes reacting an aromatic diimide with a substituted or unsubstituted phthalic anhydride in an aqueous medium in the presence of an amine exchange catalyst to provide an aqueous reaction mixture including an N-substituted phthalimide, an aromatic tetraacid salt, and at least one of an aromatic triacid salt and an aromatic imide diacid salt. The method further includes removing the phthalimide from the aqueous reaction mixture by extracting the aqueous reaction mixture with an organic solvent and converting to the corresponding aromatic dianhydride. The extracting is carried out in an extraction column including a high specific surface area metal packing material and having an interface between the aqueous reaction mixture and the organic solvent that is at a level that is 14 to 85% of the height of the extraction column.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.