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US 6,649,798 B2Granted
Method for production of diaminodiphenylmethanes
AssigneeBayer Aktiengesellschaft
InventorsStephan Klein, Dirk Grotjohann, Christine Mendoza-Frohn, Daniel Koch, Heinz-Herbert Müller, Hans-Georg Pirkl, Rudolf Uchdorf, Gerhard Wegener
Life of this patent
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Abstract
The present invention concerns a process for the production of methylenedianiline (MDA) having a high monomer content.
Claims7
A process for the production of methylenedianilines comprising (1) condensing aniline which contains less than 100 ppm aliphatic amines, and a methylene group-supplying agent, at a molar ratio of aniline to methylene group-supplying agent of 1.7:1 to 100:1 to form a condensate of aniline and the methylene group-supplying agent;
- (2) drying the condensate of aniline and the methylene group-supplying agent;
- and (3) rearranging the dried condensate under gentle conditions in the presence of solid, inorganic, acid catalysts to form low-polymer methylenedianiline with a predominant 4,4′-isomer content.
Dependencies are inferred from the claim text.