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:
Apr. 15, 2003
Filed:
Dec. 12, 2001
Applicant:
Inventors:
Wolfgang Alewelt, Krefeld, DE;
Steffen Kühling, Meerbusch, DE;
Assignee:
Bayer Aktiengesellscaft, Leverkusen, DE;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C07C 6/996 ;
U.S. Cl.
CPC ...
C07C 6/996 ;
Abstract
An improvement to the interfacial boundary process for producing carbonic acid diaryl esters is disclosed. In the two-stage process that entails phosgene and monophenols reaction in an inert solvent, in the presence of alkali and in the presence of a nitrogen base catalyst, the improvement comprising maintaining a temperature below 50° C. in the first and second stages.