Process for the production of di- and polyamines of the diphenylmethane series

• US 7,312,362 B2
• Filed: 01/24/2007
• Issued: 12/25/2007
• Est. Priority Date: 01/28/2006
• Status: Active Grant

• Current Assignee: Covestro Deutschland AG
• Original Assignee: Bayer Materialscience AG (Covestro AG)
• Inventors: Pohl, Fritz, Keggenhoff, Berthold, Adamson, Richard, Uchdorf, Rudolf
• Primary Examiner(s): Barts; Samuel A.
• Application Number:
  US11/657,338
• Publication Number:
  US 20070179317A1
• Time in Patent Office: 335 Days
• Field of Search: None
• US Class Current: 564/397
• 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 209/84 Purification
• 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
• CPC Class Codes: C07C 263/10 by reaction of amines with carbonyl halides, e.g. with phosgene
• CPC Class Codes: C07C 265/14 containing at least two isocyanate groups bound to the same carbon skeleton

Abstract

The present invention relates to a process for the production of mixtures of di- and polyamines of the diphenylmethane series (MDA) containing less than 1,000 ppm of water and less than 200 ppm of aniline by reaction of aniline and formaldehyde in the presence of acid catalysts and subsequent separation of the acid catalyst and subsequent distillative separation of water and aniline in an at least a two-stage distillation including a flash evaporation and subsequent cooling.

Claims

1. A process for the production of di- and polyamines of the diphenylmethane series comprising:

a) reacting aniline and formaldehyde in the presence of an acid catalyst to produce a reaction mixture containing di- and polyamines;

b) neutralizing the reaction mixture containing di- and polyamines;

c) separating the neutralized reaction mixture containing di- and polyamines into an organic phase containing di- and polyamines and an aqueous phase;

d) separating by distillation the water and aniline from the organic phase containing di- and polyamines;

wherein

d1) the distillation in step d) comprises at least one pre-evaporation stage and at least one distillation stage,

d2) aniline and water are partially separated off in the pre-evaporation stage from the organic phase containing di- and polyamines by flash evaporation, and

d3) in the subsequent distillation stage, the remaining aniline and water are separated off, such that di- and polyamines containing less than about 1,000 ppm of water and less than about 200 ppm of aniline, based on the weight of the di- and polyamines, are obtained and

e) cooling the di- and polyamines containing less than about 1,000 ppm of water and less than about 200 ppm of aniline.

2. The process according to claim 1, wherein the cooling of the di- and polyamines containing less than about 1,000 ppm of water and less than about 200 ppm of aniline in step e) takes place by heat exchange with the organic phase containing di- and polyamines before or during the distillation thereof in step d).

3. The process according to claim 1, wherein the pre-evaporation of the organic phase containing di- and polyamines in step d2) takes place by at least a two-stage flash evaporation and with feed of heat which is exchanged by heat exchange of the organic phase containing di- and polyamines with the stream of di- and polyamines containing less than about 1,000 ppm of water and less than about 200 ppm of aniline.

4. The process according to claim 1, wherein the mixture of aniline and water obtained in step d3) as distillate contains less than about 0.5 wt. % of di- and polyamines, based on the weight of the aniline.

5. The process for the production of di- and polyisocyanates of the diphenylmethane series, wherein di- and polyamines are produced according to the process of claim 1 and reacted with phosgene to the corresponding di- and polyisocyanates.