The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 29, 1994
Filed:
Oct. 15, 1992
William D McGhee, St. Louis, MO (US);
Thomas E Waldman, Chesterfield, MO (US);
Monsanto Company, St. Louis, MO (US);
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 phosphazene compound or a mixture of a phosphazene compound and an 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 phosphazene compound or a mixture of a phosphazene compound and an organic, nitrogenous base selected from the group consisting of guanidine compounds, amidine compounds, tertiary amines, pyridine and mixtures thereof.