Method of producing diamines and polyamines of the diphenylmethane series

Patent metadata

Field	Value
Publication number	US-10640453-B2
Application number	US-201716470288-A
Country	US
Kind code	B2
Filing date	Dec 18, 2017
Priority date	Dec 22, 2016
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

The invention relates to a method for producing diamines and polyamines of the diphenylmethane series, by condensing aniline and formaldehyde followed by an acid-catalysed rearrangement at different production capacities with alteration of the isomer composition in the resulting diamines of the diphenylmethane series (altering the 2,4′-MDA content). Adapting the molar ratios of the total used aniline to the total used formaldehyde and of the total used acid catalyst to the total used aniline, and adapting the reaction temperature, allows the rearrangement reaction to be fully completed despite the change in dwell time inevitably associated with a change in production capacity, and allows the formation of undesired by-products to be avoided as far as possible; the intended modification to binuclear content is likewise achieved.

First claim

The invention claimed is:

1. A process for preparing di- and polyamines of the diphenylmethane series from aniline ( 1 ) and formaldehyde ( 2 ) in a production plant ( 10 000 ), where the molar ratio of total aniline used ( 1 ) to total formaldehyde used ( 2 ), n(1)/n(2), is always not less than 1.6, comprising:
(A-I) reacting aniline ( 1 ) and formaldehyde ( 2 ) in the absence of an acidic catalyst to obtain a reaction mixture ( 4 ) comprising an aminal ( 3 ), and then at least partly separating an aqueous phase ( 6 ) from the reaction mixture ( 4 ) to obtain an organic phase ( 5 ) comprising the aminal ( 3 );
(A-II) contacting the organic phase ( 5 ) which comprises the aminal obtained in step (A-I) with an acidic catalyst ( 7 ) in a reactor cascade ( 3000 ) composed of i reactors connected in series ( 3000 - 1 , 3000 - 2 , . . . , 3000 - i ), where i is a natural number from 2 to 10, wherein:
the first reactor ( 3000 - 1 ) in flow direction is operated at a temperature T 3000-1 in the range from 25.0° C. to 65.0° C. and is charged with stream ( 5 ) and acidic catalyst ( 7 ) and optionally with further aniline ( 1 ) and/or further formaldehyde ( 2 ),
every reactor downstream in flow direction ( 3000 - 2 , . . . , 3000 - i ) is operated at a temperature of more than 2.0° C. above T 3000-1 and is charged with the reaction mixture obtained in the reactor immediately upstream;

(B) isolating the di- and polyamines of the diphenylmethane series from the reaction mixture ( 8 - i ) obtained from step (A-II) in the last reactor ( 3000 - i ) by a process comprising:
(B-I) adding a stoichiometric excess of base ( 9 ), based on the total amount of acidic catalyst used ( 7 ), to the reaction mixture ( 8 - i ) obtained in the last reactor ( 3000 - i ) in step (A-II) to obtain a reaction mixture ( 10 ); and
(B-II) separating the reaction mixture ( 10 ) obtained in step (B-I) into an organic phase ( 11 ) comprising di- and polyamines of the diphenylmethane series and an aqueous phase ( 12 );

wherein
in the event of a change in the production capacity from a starting state A with
a mass flow rate m 1 of total aniline used in the starting state of m 1 (A)≠0,
a mass flow rate m 2 of total formaldehyde used in the starting state of m 2 (A)=X(A)·m 2 (N), where X(A) is a dimensionless number >0 and ≤1 and m 2 (N) denotes the nameplate load of the production plant ( 10 000 ),
a molar ratio n(1)/n(2) of total aniline used ( 1 ) to total formaldehyde used ( 2 ) in the starting state of n(1)/n(2)(A),
a molar ratio n(7)/n(1) of total acidic catalyst used to total aniline used in the starting state of n(7)/n(1)(A),
a proportion by mass ω MMDA , based on the total mass of di- and polyamines of the diphenylmethane series, of diamines of the diphenylmethane series of ω MMDA (A), and
a proportion by mass ω 2,4′-MDA , based on the total mass of diamines of the diphenylmethane series, of 2,4′-methylenediphenyldiamine in the starting state of ω 2,4′-MDA (A)

to an end state E with
a mass flow rate m 1 of total aniline used of in the end state m 1 (E)≠0,
a mass flow rate m 2 of total formaldehyde used in the end state of m 2 (E)=X(E)·m 2 (N), where X(E) is a dimensionless number >0 and ≤1,
a molar ratio n(1)/n(2) of total aniline used ( 1 ) to total formaldehyde used ( 2 ) in the end state of n(1)/n(2)(E),
a molar ratio n(7)/n(1) of total acidic catalyst used to total aniline used in the end state of n(7)/n(1)(E),
a proportion by mass ω MMDA , based on the total mass of di- and of the diphenylmethane series, of diamines of the diphenylmethane series the end state of ω MMDA (E), and
a target proportion by mass ω 2,4′-MDA for the end state, based on the total mass of diamines of the diphenylmethane series, of 2,4′-methylenediphenylenediamine, of ω 2,4′-MDA (E);

by a quantity ΔX=|X(E)−X(A)|, with ΔX≥0.10, wherein the process comprises at least one change in production capacity that commences at a time t 1 and concludes at a time t 2 , wherein ω 2,4′-MDA is also altered in such a way that, for the target value of ω 2,4′-MDA (E) for the end state, either ≥1.15·ω 2,4′-MDA (A) or ≤0.85·ω 2,4′-MDA (A), and wherein:
0.95·ω MMDA ( A )≤ω MMDA ( E )≤1.05·ω MMDA ( A );

characterized in that, in the period from t 1 to t 2 , the transition state T, with a molar ratio of total aniline used ( 1 ) to total formaldehyde used ( 2 ) of n(1)/n(2)(T) and a molar ratio of total acidic catalyst used to total aniline used of n(7)/n(1)(T),
(i) the temperature in the first reactor ( 3000 - 1 ) in flow direction from step (A-II) is adjusted to a value that differs from the temperature in that reactor during the starting state A by not more than 10.0° C.;
(ii-1) in the case that m 2 (E)>m 2 (A), the temperature in at least one of the reactors downstream in flow direction ( 3000 - 2 , . . . , 3000 - i ), by comparison with the starting state A, is increased by more than 2.0° C. in such a way that the target end temperature is reached at the latest at time t 2 , and in all reactors ( 3000 - 2 , . . . , 3000 - i ) in which the temperature is not increased it is kept the same within a range of variation of ±2.0° C.;
(ii-2) in the case that m 2 (E)<m 2 (A), the temperature in at least one of the reactors downstream in flow direction ( 3000 - 2 , . . . , 3000 - i ), by comparison with the starting state A, is lowered by more than 2.0° C. in such a way that the target end temperature is reached at the latest at time t 2 , and in all reactors ( 3000 - 2 , . . . , 3000 - i ) in which the temperature is not lowered it is kept the same within a range of variation of ±2.0° C.;
(iii-1) in the case that ω 2,4′-MDA (E)≥1.15·ω 2,4′-MDA (A), n(1)/n(2)(T) and n(7)/n(1)(T) are adjusted in such a way that, at time t 2 :
1.01· n (1)/ n (2)( A )≤ n (1)/ n (2)( T )≤1.50· n (1)/ n (2)( A ), and

0.50· n (7)/ n (1)( A )≤ n (7)/ n (1)( T )≤0.95· n (7)/ n (1)( A );

wherein, over the entire transition state before reaching time t 2 , it is always the case that:
0.80· n (1)/ n (2)( A )≤ n (1)/ n (2)( T )≤2.50· n (1)/ n (2)( A ), and

0.40· n (7)/ n (1)( A )≤ n (7)/ n (1)( T )≤1.15· n (7)/ n (1)( A );

(iii-2) in the case that ω 2,4′-MDA (E)≤0.85·ω 2,4′-MDA (A), n(1)/n(2)(T) and n(7)/n(1)(T) are adjusted in such a way that, at time t 2 :
0.75· n (1)/ n (2)( A )≤ n (1)/ n (2)( T )≤0.99· n (1)/ n (2)( A ), and

1.05· n (7)/ n (1)( A )≤ n (7)/ n (1)( T )≤3.50· n (7)/ n (1)( A ),

wherein, over the entire transition state before reaching time t 2 , it is always the case that:
0.40· n (1)/ n (2)( A )≤ n (1)/ n (2)( T )≤2.00· n (1)/ n (2)( A ), and

0.80· n (7)/ n (1)( A )≤ n (7)/ n (1)( T )≤4.50· n (7)/ n (1)( A ).

2. The process of claim 1 , in which the temperature in the reactors of the reactor cascade 3000 increases from reactor 3000 - 1 to reactor 3000 - i in all states of operation (A, T, E).

3. The process of claim 1 , in which it is always the case that
T 3000-1 is set to a value in the range from 25.0° C. to 65.0° C. and
the temperature in each of the reactors downstream in flow direction ( 3000 - 2 , . . . , 3000 - i ) is set to a value in the range from 35.0° C. to 200.0° C.

4. The process of claim 3 , in which it is always the case that
T 3000-1 is set to a value in the range from 30.0° C. to 60.0° C. and
the temperature in each of the reactors downstream in flow direction ( 3000 - 2 , . . . , 3000 - i ) is set to a value in the range from 50.0° C. to 180.0° C.

5. The process of claim 1 , in which the acidic catalyst ( 7 ) is a mineral acid.

6. The process of claim 1 , in which step (B) further comprises:
(B-III) washing the organic phase ( 11 ) with washing liquid ( 13 );
(B-IV) separating the mixture ( 14 ) obtained in s

Assignees

• Covestro Deutschland Ag

Inventors

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

Classifications

• C07C209/54 Primary

  by rearrangement reactions · 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

• C07C211/48

  N-alkylated amines · CPC title

• C07C211/50

  with at least two amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton · CPC title

• C07C209/60

  by condensation or addition reactions, e.g. Mannich reaction, addition of ammonia or amines to alkenes or to alkynes or addition of compounds containing an active hydrogen atom to Schiff's bases, quinone imines, or aziranes · CPC title