Method for production of diaminodiphenylmethanes

• US 6,649,798 B2
• Filed: 08/07/2002
• Issued: 11/18/2003
• Est. Priority Date: 02/14/2000
• Status: Expired due to Fees

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Klein, Stephan, Pirkl, Hans-Georg, Koch, Daniel, Grotjohann, Dirk, Wegener, Gerhard, Uchdorf, Rudolf, Mendoza-Frohn, Christine, Müller, Heinz-Herbert
• Primary Examiner(s): BARTS, SAMUEL A
• Application Number:
  US10/203,250
• Publication Number:
  US 20030023116A1
• Time in Patent Office: 468 Days
• Field of Search: 564/332, 564/331
• US Class Current: 564/332
• CPC Class Codes: C07C 209/78 from carbonyl compounds, e.g. from formaldehyde, and amines having amino groups bound to carbon atoms of six-membered aromatic rings, with formation of methylene-diarylamines
• CPC Class Codes: C07C 211/50 with at least two amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton

Abstract

The present invention concerns a process for the production of methylenedianiline (MDA) having a high monomer content.

Claims

1. 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.

2. The process according to claim 1, wherein said rearranging of the dried condensate is performed in at least two stages at a temperature that increases between the stages.

3. The process according to claim 1, wherein said aniline contains less than 25 ppm aliphatic amines.

4. The process according to claim 1, wherein the catalysts are selected from the group consisting of powdered zeolites and zeolite mouldings in the H⁺ form, which are present in suspension or as fixed beds.

5. The process according to claim 1, wherein said rearranging is performed batchwise in a stirred-tank reactor, continuously in a stirred-tank reactor, in a series of stirred-tank reactors, in a tubular reactor, in a fixed-bed reactor, in a fluidized-bed reactor or in a combination thereof.

6. The process according to claim 1, wherein the condensate of aniline and the methylene group-supplying agent comprises an aminal or a solution thereof that contains less than 1000 ppm water.

7. The process according to claim 1, wherein said catalysts comprise FAU zeolites.