Process for preparing isocyanates
US5349081A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 21, 1993 |
| Grant date | Sep 20, 1994 |
| Priority date | — |
| Expiry date | Jan 21, 2013 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C263/04
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process for preparing isocyanates comprising (a) 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, pyridine and mixtures thereof to produce the corresponding ammonium carbamate salt, and (b) reacting the ammonium carbamate salt with an electrophilic or oxophilic dehydrating agent to produce the corresponding isocyanate. A second embodiment comprises recovering the ammonium carbamate salt of step (a) prior to reacting the ammonium carbamate salt with an electrophilic or oxophilic dehydrating agent 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, pyridine and mixtures thereof.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.