Process for preparing isocyanate and carbamate ester products
US5233010A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 1992 |
| Grant date | Aug 3, 1993 |
| Priority date | — |
| Expiry date | Oct 15, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P20/582
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process for preparing an isocyanate having at least two --N.dbd.C.dbd.O groups is provided which comprises preparing a substituted aromatic amine having at least two --NH.sub.2 groups, recovering the substituted aromatic amine having at least two --NH.sub.2 groups, and preparing an isocyanate from the substituted aromatic amine having at least two --NH.sub.2 groups by (1) contacting the substituted aromatic amine with CO.sub.2 under conditions sufficient to produce the corresponding ammonium carbamate salt, and reacting the ammonium carbamate salt with an electrophilic or oxophilic dehydrating agent under conditions sufficient to produce the corresponding isocyanate, or (2) contacting the substituted aromatic amine with CO.sub.2 under conditions sufficient to produce the corresponding ammonium carbamate salt, reacting the ammonium carbamate salt with a primary or secondary hydrocarbyl halide in a polar aprotic solvent under conditions sufficient to produce the corresponding carbamate ester, and cracking the carbamate ester under conditions sufficient to produce the corresponding isocyanate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.