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:
Jun. 15, 1993
Filed:
Oct. 19, 1992
Applicant:
Inventors:
Carmen L Rodriguez, Exton, PA (US);
Edward T Shawl, Wallingford, PA (US);
Haven S Kesling, Jr, Drexel Hill, PA (US);
Assignee:
Arco Chemical Technology, L.P., Wilmington, DE (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C07C / ;
U.S. Cl.
CPC ...
564 50 ; 564 55 ;
Abstract
A selective process for the preparation of diphenylmethane bis(dialkylureas) is disclosed. An alkyl phenylcarbamate or an N,N-dialkyl-N'-phenylurea is reacted with a methylene bis(alkyl carbamate) in the presence of an acid catalyst. The use of a staged addition of phenylcarbamate or phenylurea to the methylene bis(carbamate) and the use of a ramped temperature program are the keys to good selectivity to MDI dimer products.