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. 15, 2006
Filed:
Jun. 25, 2003
Bernd Jaeger, Darmstadt, DE;
Thomas Haas, Frankfurt, DE;
Guido Stochniol, Haltern, DE;
Christian Lettmann, Essen, DE;
Willi Hofen, Rodenbach, DE;
Klaus Stadtmueller, Alzenau, DE;
Joerg Lotz, Kalbach, DE;
Bernd Jaeger, Darmstadt, DE;
Thomas Haas, Frankfurt, DE;
Guido Stochniol, Haltern, DE;
Christian Lettmann, Essen, DE;
Willi Hofen, Rodenbach, DE;
Klaus Stadtmueller, Alzenau, DE;
Joerg Lotz, Kalbach, DE;
Degussa AG, Duesseldorf, DE;
Abstract
The invention relates to a process for increasing the selectivity of the hydrogenation of 4,4'-diaminodiphenylmethane (4,4′-MDA) to diaminodicyclohexylmethane (4,4′-HMDA) by catalytic hydrogenation of a mixture containing 4,4′-MDA as the main component and its mono-N-methyl derivative as a secondary component. According to the invention, the hydrogenation is terminated before a conversion of 4,4′-MDA to 4,4′-HMDA of 99% is achieved. Under these conditions, a substantially smaller proportion of the N-methyl-4,4′-MDA is hydrogenated to N-methyl-4,4-HMDA.