Process for increasing the selectivity of the hydrogenation of 4,4′-diaminodiphenylmethane to 4,4′-diaminodicyclohexylmethane in the presence of an N-alkyl-4,4′-diaminodiphenylmethane

US7091384B2 · kind B2 · utility

Assignee

• Degussa AG · DE

Inventors

• Bernd Jaeger · Emmelshausen, DE
• Thomas Haas · Munster, DE
• Guido Stochniol · Haltern am See, DE
• Christian Lettmann · Coesfeld, DE
• Willi Hofen · Rodenbach, DE
• Klaus Stadtmueller · Alzenau, DE
• Joerg Lotz · Schlüchtern, DE

Key dates

• Filing date: Jun 25, 2003
• Grant date: Aug 15, 2006
• Expiry date: Sep 3, 2023

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C211/36
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

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.