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

Patent metadata

Field	Value
Publication number	US-10125090-B2
Application number	US-201515317301-A
Country	US
Kind code	B2
Filing date	Jun 22, 2015
Priority date	Jun 24, 2014
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

The invention relates to a method for the preparation of di- and polyamines of the diphenylmethane series, care being taken during the shutdown of the production process that an excess of aniline and respect to formalin is ensured.

First claim

The invention claimed is:

1. A process for preparing diamines and polyamines of the diphenylmethane series (MDA) by reaction of aniline (1) and formaldehyde (2) at a molar ratio of aniline (1) to formaldehyde (2) in normal operation of A/F normal operation , which comprises the steps:
A.I) reacting aniline (1) and formaldehyde (2) in the absence of an acid catalyst (3) in a reactor to form an aminal, where aniline (1) is introduced at a mass flow rate m 1 and formaldehyde (2) is introduced at a mass flow rate m 2 into the reactor and the resulting reaction mixture is subsequently separated into an aqueous phase and an organic, aminal-containing phase; and
A.II) reacting at least part of the organic, aminal-containing phase obtained in step A.I) with acid (3) in a reactor, with the aminal reacting to form diamines and polyamines of the diphenylmethane series;
wherein the following steps are carried out to end the production of the diamines and polyamines of the diphenylmethane series:
A.I.1) reducing the mass flow rate m 2 of the formaldehyde (2) into the reactor of step A.I), commencing at a point in time t 0 , until m 2 is zero at a point in time t 1 , where t 1 >t 0 ;
A.I.2) reducing the mass flow rate m 1 of the aniline into the reactor of step A.I) until m 1 is zero at a point in time t 2 , where t 2 ≥t 1 ; and
A.II.1) reducing the mass flow rate m 3 of acid (3), until m 3 zero;
and

the reduction of the mass flow rates m 1 and m 2 occurs in such a way that, up to attainment of the point in time t 1 , the instantaneous molar ratio of
aniline (1) introduced into the reactor of step A.I)
to
formaldehyde (2) introduced into the reactor of step A.I),
A/F inst. , is always ≥1.5 and is always ≥1.05·A/F normal operation .

2. The process as claimed in claim 1 , wherein the steps I) and II) are carried out in the form of a continuous process.

3. The process as claimed in claim 1 , wherein the mixture obtained is also discharged from the respective reactor during and/or after step A.I).

4. The process as claimed in claim 1 , wherein t 2 −t 1 is >0 hour.

5. The process as claimed in claim 1 , wherein the mass flow rate m 1 is ≥1000 kg/hour.

6. The process as claimed in claim 1 , wherein the mass flow rate m 2 is ≥300 kg/hour.

7. The process as claimed in claim 1 , wherein at least the reactor of step A.I) is at least partly full of aniline after the point in time t 2 .

8. The process as claimed in claim 1 , wherein the mass flow rate m 3 of acid (3) is reduced at the earliest commencing at the point in time t 1 .

9. The process as claimed in claim 8 , wherein the mass flow rate m 3 prevailing before step A.I.1) is carried out is maintained up to the point in time t 2 .

10. The process as claimed in claim 8 , wherein the introduction of further acid (3) is stopped at the point in time t 2 .

Assignees

• Covestro Deutschland Ag

Inventors

• Knauf Thomas
• Wershofen Stefan
• Gruner Klaus-Gerd
• Hartjes Volker

Classifications

• C07C209/82

  Purification; Separation; Stabilisation; Use of additives · CPC title

• C07C209/78 Primary

  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 title

• B01D17/02

  Separation of non-miscible liquids · CPC title

• Y02P20/582

  Recycling of unreacted starting or intermediate materials · CPC title

• B01D3/00

  Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping ({evaporation in general, e.g. of liquids for gas phase reactions B01B1/005;} gas chromatography B01D15/08; destructive distillation C10B; preparation of alcoholic beverages by distillation C12H6/02) · CPC title