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:
Aug. 03, 1993
Filed:
Oct. 15, 1992
William D McGhee, St. Louis, MO (US);
Michael K Stern, University City, MO (US);
Thomas E Waldman, Chesterfield, MO (US);
Monsanto Company, St. Louis, MO (US);
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.