Process for preparing isocyanates
US5451697A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 27, 1993 |
| Grant date | Sep 19, 1995 |
| Priority date | — |
| Expiry date | Dec 27, 2013 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C263/04
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process for preparing isocyanates comprising contacting carbon dioxide and a primary amine in the presence of an aprotic organic solvent and a base selected from the group consisting of a phosphazene compound, an organic, nitrogenous base and mixtures thereof, wherein the organic, nitrogenous base selected from the group consisting of guanidine compounds, amidine compounds, tertiary amines and mixtures thereof to produce the corresponding ammonium carbamate salt, reacting the ammonium carbamate salt with an anhydride dehydrating agent to produce a product stream comprising the corresponding isocyanate, the aprotic organic solvent and the base salt derived from the anhydride, separating the base salt from the product stream, recovering and recycling the base, and regenerating and recycling the anhydride dehydrating agent.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.