DE19613553A1 - Integrated production and fractionation of aromatic poly:amine mixtures - Google Patents

Abstract

A process for the production of aromatic polyamine mixtures (I) with integrated fractionation and/or purification, by reacting aryl amines (II) with carbonyl compounds, especially formaldehyde (III), in presence of acid catalysts (IV) and water (at least in the last stage of the rearrangement), and optionally in series with a separate "aminal stage" to form N,N'- disubstituted condensation products in the absence of (IV) and optionally in presence of hydrophobic solvents (V). In this process, (a) the 2-phase reacted mixture (01) is (d) separated in separator C-1 into organic phase (02) and aqueous phase (03), optionally (b) after adding (II) and/or water and/or strong acid (as salts of (II) and possibly (I)), preferably in the form of a recycled aqueous phase (17), (18) and/or (19), and optionally (c) after adding hydrophobic solvent (V) which may contain (II) and/or (I); organic phase (02) is taken to counter-current extraction (C-2) against an aqueous phase containing water , acid as ammonium salts, (II) and possibly small amounts of (I), and consisting of at least parts of streams (17) and/or (18) and/or (19), in an amount such that the polyamine (I) in phase (02) is transferred quantitatively to the resulting aqueous phase (04) which is then (f) taken to extraction C-4, optionally (e) via extraction stage C-3; the polyamine-free organic phase (05) from C-2, optionally (g) after passing through extraction stage C-4 or (h) through C-4 and then C-3, is (i) recycled at suitable point(s) in the reaction sequence, but before the reaction mixture reaches separator C-1; aqueous phase (03) from C-1 is extracted in (C-4) with an organic phase (06) containing (V), generally (II) and possibly (I), which is adjusted so that the polyamine is partitioned in a controlled manner between the resulting organic (07) and aqueous phase (08) and the composition of the polyamine fraction differs as required; organic phase (07), optionally (k) via extraction C-3, or (l) after separating a part which is taken to C-2, or (m) passing through extraction C-3 and separating a part which is taken to C-2 before and/or after passing through C-3, or (n) passing through an at least 2-stage extraction C-3 comprising part-stages C-32 and C-33 and separating a part as in (m), is recycled into the reaction sequence before the end, i.e. in reactor B-1, B-3 and/or B-4, and/or passed through a washing and/or neutralisation stage to a preferably multi-stage distillation (D-3)/(D-4) and separated into a fraction (09) containing (V) and possibly (II), a fraction (10) containing (II) and possibly (V), and a residue (11) (first polyamine fraction); the aqueous phase from C-4, optionally (p) after adding water and/or (II), is (q) extracted in C-5 with an organic phase (12) containing (V), (II) and possibly small amounts of (I); the resulting polyamine-containing organic phase (13) is taken via wash/neutralisation stage (E-2) and distilled in stage (E) to give distillate fraction(s) (14) containing (V) and (II) and a residue (16) (second polyamine fraction); the polyamine-free aqueous phase (17) from C-5), optionally (r) after removing water in evaporator (C-7) to form stream (18) or (s) extracting amine in stage C-6 to increase the degree of protonation, is re-used, by returning (17), and/or (18) and/or (19) (if present), partly to the reaction sequence as a catalyst solution and partly to extraction stage C-2, any remaining residue being added to the reaction mixture as in (b) and/or taken to stage C-3.

Description

The invention relates to a method for manufacturing with integrated frac tioning and cleaning of aromatic polyamine mixtures and de use.

The production of aromatic polyamines and polyamine mixtures the diphenylmethane series in particular is described in numerous patent mel dations and patents, as well as the use of this pro products. The use of these is of great importance Products as raw materials for the production of isocyanates, in which Re gel by reacting the polyamine mixtures with phosgene after all commonly used and known methods.

The resulting isocyanates or isocyanate mixtures fall into many cases but not in the form and composition as they preferably used on the isocyanate stage, but must previously through partially complex processing and separation processes be converted into the appropriate form. Suitable poly amine precursors that are less expensive to use in the isocyanate in many cases are procedural difficult or not at all or economically unattractive to produce.

One example is the extraction of high-quality poly for the production urethane materials important 4,4'-diisocyanato-diphenylmethane, the Amine precursor usually only together from aniline and formaldehyde with isomers, especially the 2,4'-isomer, and higher functional Polyamines can be obtained. While these components are the The basis for coveted isocyanates, too, is the separation the raw isocyanates into the Isocya suitable for further use nate or isocyanate mixtures not easy.

As a rule, part of the dual-core connections of separated from the rest. Then the two-core fraction in egg nem the second distillation step requiring many separation stages 4,4'-diisocyanato-diphenylmethane freed from the other isomers.

The 2,4′-isomer in enriched form has also increased recently gaining importance as a polyurethane raw material, and can only be with considerable distillative effort compared to the 4,4'-isomer enriched and freed of any 2,2'-isomers present will.

Isomer separation process or enrichment process within the Fraction of higher core homologues or higher functional Be Components of the amines as well as the isocyanates of the diphenylmethane series are practically unknown.  

The 4,4′-diamino-diphenylmethane is also gaining interest as raw material for the di- (4-isocyanatocyclohexyl) methane, the kernhy third form of 4,4'-diisocyanato-diphenylmethane, the ready provision of suitable aromatic polyamine mixtures for the hydrogenation stage with the highest possible 4,4′-diamino-diphenylmethane content at the same time the smallest possible proportion of 2,4'-diamino-diphenyl methane is very expensive.

It is known that amines are converted into their salts by partial conversion into certain cases can be separated, where u. a. the difference base strengths can be used. This is usually the case monoamines with very different base strengths.

Also for aromatic polyamine mixtures, especially diphenylme than series, are such disproportionation effects in two-phase sy already described (DE-A 22 38 379, DE-A 25 28 694).

The effects are due to those present in such a mixture numerous components whose amino groups are of the type here - practically all are arylamino groups - hardly distinguish, not particularly ders large and distinctive in order for direct use with simple Means to be interesting.

The task was therefore to provide a method that it permitted, polyamine mixtures in a purer, new composition To produce economically and gently.

This object was achieved by the method according to the invention, which due to the inventive design in combination with the Production of surprisingly high separation performance in the fractionation of aromatic polyamine mixtures achieved, and the effect far goes beyond the known effects of the prior art will.

In the integrated in the manufacturing process according to the invention Fractionation of aromatic polyamine mixtures are in Aufar processing part of the process isolated and recovered process products, whose composition is different from the composition of the primary reaction products formed in the reaction part of the process.

These derived polyamine mixtures can be such act, which are very expensive to access on known synthetic routes are. It can also be polyamine mixtures that are more suitable for simplified production of the isocyanates, than the well-known and technically easy to manufacture polyamine mixtures, by z. B. on the isocyanate stage difficult to carry out Anticipate separations at the amine level. Such mixtures can also be completely new, because according to the state of the art not representable polyamine mixtures that lead to completely new isocyanates to lead.  

The method according to the invention can also be used for this Synthesis-related and undesirable secondary and intermediate in the end product products, to be fractionated and taken off and on in a product fraction to be enriched accordingly in another, possibly in an egg to discharge the relevant fraction.

The present invention is widely applicable Process with which the task of manufacturing, fractionation and Cleaning of aromatic di- and polyamine mixtures can be solved can.

The invention relates to a method for manufacturing with integrier ter fractionation and / or purification of aromatic polyaminemi by reacting starting arylamine or starting aryl amine mixtures with carbonyl compounds, especially formaldehyde, in the presence of acidic catalysts and in the presence of water at least in the last part of the rearrangement reaction and if necessary with a separate "aminal stage" to form N, N'-disubstituted condensation products in the absence of acidic catalyzes and optionally in the presence of a hydrophobic solvent tel in one or more stages of the reaction process, which is characterized in that one

• a) the fully reacted
• b) optionally after addition of starting arylamine and / or water and / or a strong acid in the form of its ammonium salts of starting arylamine and optionally polyamine, which are preferably in the form of the recycled aqueous phase ( 17 ) and / or ( 18 ), and / or ( 19 ) is used, and
• c) optionally after addition of hydrophobic solvent, wel can contain starting arylamine and / or polyamines,
• d) two-phase reaction mixture ( 01 ) in a separator (C-1) on separates into an organic phase ( 02 ) and into an aqueous phase ( 03 ) and the organic phase ( 02 ) at least partially in an extraction stage which preferably works in several stages (C -2) counteracts an aqueous phase containing essentially water, a strong acid in the form of its ammonium salts, starting arylamine and optionally small amounts of polyamine and formed at least from subsets of the stream ( 17 ) and / or the streams which may be present ( 18th ) and / or ( 19 ), the amount is such that the polyamine contained in the organic phase ( 02 ) fed largely, possibly practically quantitatively into the resulting aqueous phase ( 04 ), which is carried out
• e) optionally via the extraction stage (C-3)
• f) the extraction stage (C-4) and the resulting, largely free of polyamine organic phase ( 05 )
• g) optionally at least partially via the extraction stage (C-4) or
• h) if necessary, at least partially, initially via the extraction stage (C-4) and then at least partially over the Extrak level (C-3)
• i) at least partially recycled at a suitable point or in partial streams at several points in the reaction sequence, but at the latest in the reaction mixture before it enters the separator (C-1), and the aqueous phase ( 03 ) together with that in the extraction stage (C-2) resulting and optionally via (C-3) led aqueous phase initially in the one or preferably multi-stage extraction stage (C-4) of an organic phase ( 06 ) containing hydrophobic solvent, usually starting arylamine and optionally Polyamine, which is measured in terms of quantity and its composition is such that the polyamine fed to process stage (C-4) is controlled in a wide range on the resulting organic phase ( 07 ) and the resulting aqueous phase ( 08 ) Way distributed in terms of quantity and the different composition of the resulting polyamine fractions is adjusted and the resulting organic phase ( 07 )
• k) optionally at least partially via the extraction stage (C-3) or
• l) if appropriate after removal of one of the extraction stages (C-2) supplied subset or
• m) optionally at least partially via the extraction stage (C-3) and separation of a part fed to the extraction stage (C-2) quantity before and / or after going through the extraction stage (C-3) or
• n) if necessary at least partially via one of the two Sub-levels (C-32) and (C-32) existing, in total at least two-stage extraction stage (C-3) optionally under Removal of a subset fed to the extraction stage (C-2) before and / or after going through the extraction stage (C-3)
• o) in the course of the reaction before the end of the reaction, ie in the reactors (B-1) and / or (B-3) and / or (B-4), recycled and / or via a washing and / or neutralization step in one preferably, multi-stage distillation stage (D-3), (D-4) in a first distillate fraction ( 09 ) containing hydrophobic solvent and optionally starting arylamine, a second distillate fraction ( 10 ) containing starting arylamine and optionally hydrophobic solvent, and in a distillation residue ( 11 ), consisting essentially of a first polyamine fraction, and the aqueous phase ( 08 ) leaving the extraction stage (C-4)
• p) optionally after adding water and / or starting aryl amine
• q) in a multi-stage extraction stage (C-5) leads, in which cher, according to the principle of countercurrent extraction, the extraction of the polyamine from the aqueous phase supplied by means of an organic phase ( 12 ) containing hydrophobic solvent, starting arylamine and optionally small amounts of polyamine, and the resulting polyamine-containing organic phase ( 13 ) at least partially via a washing and / or neutralization stage (E-2) in an optionally multi-stage distillation stage (E) in at least one distillate fraction ( 14 ) containing hydrophobic solvent and Starting arylamine, and in a distillation residue ( 16 ), consisting essentially of a second polyamine fraction, and the resulting, largely polyamine-free aqueous phase ( 17 )
• r) optionally at least partially via a water evaporation stage (C-7) with the removal of water by distillation and formation of a mass flow ( 18 ) and / or
• s) if necessary at least partially via a downstream extraction stage (C-6) with the removal of amine and increasing the degree of protonation and formation of mass flow ( 19 )
• t) reused by partially leading the stream ( 17 ) and / or any streams ( 18 ) and / or ( 19 ) back into the reaction process as a catalyst solution and partly feeding it to the extraction stage (C-2) and a possibly remaining one The rest of the fully reacted reaction mixture according to b) and / or optionally the extraction stage (C-3).

The process is preferably carried out in such a way that

• m) the aqueous phase ( 17 ) depleted in polyamine in the extraction stage (C-5) and / or the aqueous phase ( 19 ) depleted in arylamine in the extraction stage (C-6) at least partially by distillation before their further use withdraws the water and an amount of water which corresponds to the water formed in the condensation reaction and, if appropriate, the amount of water introduced with the starting compounds, in particular the carbonyl compound, unless it is discharged in another way, as wastewater, and an amount of water which has also been distilled off from the aqueous Circuit at a suitable point, but at the latest before the aqueous phase enters the extraction stage (C-5), preferably after passing through the washing stages (D-1) and / or (E-1).

The process is preferably also carried out in such a way that

• n) the resulting in the extraction stage (C-5) largely freed from polyamine aqueous phase ( 17 ) at least partially in a downstream extraction stage (C-6) counteracts an organic phase containing hydrophobic solvent and optionally starting arylamine, the amine content always being smaller than in the organic phase ( 12 ) used in the extraction stage (C-5) and the resultant, lower amine content (= higher degree of protonation) than the aqueous phase ( 19 ) used, at least partially in the course of the reaction, in particular in the first course of the reaction Rearrangement level (B-3).

The process according to the invention is particularly preferably carried out in such a way that
the resulting in the extraction stage (C-4) organic phase ( 07 ) at least partially as a mass flow ( 20 ) in the extraction stage (C-3) against an aqueous phase containing essentially water, a strong acid in the form of its ammonium salts starting arylamine and optionally small amounts of polyamine and formed at least from subsets of the volume flow ( 17 ) and / or the volume flows ( 18 ) and / or ( 19 ) which may be present, which are measured in terms of quantity and in their composition such that the step ( C-3) polyamine supplied in a wide range on the resulting organic phase ( 21 ) and the resulting aqueous phase ( 22 ) in a controlled manner quantitatively distributed and the different composition of the resulting polyamine fractions is adjusted and the resulting aqueous phase ( 22nd ) the extraction stage (C-4) and the resulting organic phase ( 21 ) at least partially ge processed according to o).

The process is particularly preferably carried out in such a way that
the stream ( 20 ) in the extraction stage (C-3) instead of the low-polyamine streams ( 17 ) and / or ( 18 ) and / or ( 19 ) the polyamine-containing aqueous phase ( 04 ) resulting in the extraction stage (C-2) at least partially leads to.

The method according to the invention is particularly preferably carried out by combining the preceding embodiments with one another by
the resulting in the extraction stage (C-4) organic phase ( 07 ) at least partially in the extraction stage (C-3) of an aqueous phase containing water, a strong acid in the form of its ammonium salts, starting arylamine and optionally polyamine and formed from at least portions of the mass flow ( 17 ) and / or of the mass flows ( 18 ) and / or ( 19 ) and / or preferably from at least a part of the quantity of the aqueous phase ( 04 ) obtained in the extraction stage (C-2) is so dimensioned and adjusted in its composition that the polyamine fed to stage (C-3) is distributed in a wide range in a controlled manner to the resulting organic phase ( 21 ) and the resulting aqueous phase ( 22 ) and the different composition the resulting polyamine fractions are adjusted and the resulting aqueous phase ( 22 ) of the extraction stage (C- 4) and the resulting organic phase ( 21 ) at least partially further processed according to o).
If for the formation of the aqueous phase used in the extraction stage (C-3) both low-polymer aqueous phase in the form of the streams ( 17 ) and / or ( 18 ) and / or ( 19 ) and polyamine-containing aqueous phase in the form of the stream ( 04 ) is used, then it can bring additional advantages to subdivide the extraction stage (C-3) into the two at least one-stage sub-stages (C-31) and (C-32), which differ from the organic phase ( 20 ) used reverse order, that is to say run through (C-32) to (C-31), the organic phase in (C-21) being countered by an aqueous phase, at least predominantly formed from at least partial amounts of the low-polyamine streams ( 17 ) and / or ( 18 ) and / or ( 19 ) and in (C-32) an aqueous phase formed from the aqueous phase resulting in (C-31) and the aqueous phase ( 04 ) resulting in (C-2).

The polyamine mixtures treated in this way, ie those with the invention Fractions generated according to the method are used to produce the corresponding aromatic polyisocyanate mixtures and for the manufacture used in polyurethane plastics.

In addition, they can be produced using the method according to the invention fractions for the preparation of corresponding core-hydrogenated polyamines or used as a crosslinker and as an epoxy hardener.

The corresponding from the fractionated polyamine mixtures The polyisocyanates are preferred for the production of PU foams used or used as paint raw materials, in particular the derived nuclear hydrogenated polyisocyanates.

Examples of polyarylamine mixtures, for their preparation, fractionation tion and cleaning the method according to the invention particularly suitable is net are

• 1. Polyamine mixtures of the diphenylmethane series, as used in the Kon densation and acid catalyzed rearrangement of aniline with form aldehyde arise,
• 2. Polyamine mixtures of the diphenylmethane series, as used in the acid recatalyzed condensation of substituted anilines with form aldehyde,
• 3. Polyamine mixtures of the diphenylmethane series, as in the mixing condensation of formaldehyde with substituted anilines other and / or with aniline.  
• 4. Polyamine mixtures such as those used in condensation, including the mixture condensation of substituted anilines, naphthylamines and / or Aniline with carbonyl compounds,
• 5. Polyamine mixtures such as those used in condensation, including the mixture condensation of aryl monoamines (e.g. aniline, substituted ani line, naphthylamines) and / or monoaryl diamines (Phenylenediamines, substituted phenylenediamines) and / or Na phthylenediamines with carbonyl compounds, especially formal dehydrogen, and acid-catalyzed rearrangement arise.

The hydrophobic solvents used are involved inert solvents with a boiling point range of 30 ° - 280 ° C, preferably from 80 ° -200 ° C, such as chlorobenzene, Dichlorobenzene, benzene, toluene, ethylbenzene, cumene, xylene, dichloroethane, Chloroform and carbon tetrachloride. Preferably xylenes, i.e. H. technical xylene mixtures, especially o-xylene, toluene, ethylbenzene, Cumene and chlorobenzene used.

Those solvents are preferred which have a good sol have capacity for the polyamine mixtures used.

The acids used are water-soluble protons acids with a value below 2.5, preferably below 1.5 pKA value. Examples of these are hydrochloric acid, hydrobromic acid, sweat rock acid, trifluoroacetic acid, methanesulfonic acid or phosphoric acid.

The preferred acids used are hydrochloric acid and methanesulfone acid.

The acids mentioned lie in the aqueous phases of the invention according to the method not in free form, but as an aqueous solution solutions of their salts with the bases in the aqueous phases. These are usually the components of the order settlement formed polyamine mixtures and their fractions and / or starting arylamine used.

In addition, the aqueous phases contain different amounts but only partially solved, d. H. with part of their amino groups salzar tied polyamine components and dissolved but not salt-like bound polyamine components and starting arylamine.

The share of the salt-bound amino groups in the total number the amino groups are expressed by the degree of protonation brings.

As the starting arylamine, amines, such as, for example, B. Aniline, Na phthylamines and their substituted ones, especially their alkyl substituted ones Derivative use. Aniline is particularly preferred. Can continue phenylene and naphthylenediamines used as starting arylamines are, these always in a mixture with the monoaryl mentioned amines with a proportion of usually 50 mol% and less be set.  

The process according to the invention is generally carried out continuously guided. The process is at all stages under its own pressure of the system and preferably in an inert gas atmosphere (nitrogen) carried out.

The method according to the invention can be used to increase the concentration corresponding or depletion effect by corresponding return with each of the product fractions Feedback can be repeated.

The method according to the invention can be used with two as well as with for six extraction stages.

The flow diagrams shown in FIGS . 1 to 4 serve to further explain the method according to the invention. In these figures:

(A-1) a storage container for the starting arylamine or starting arylamine mixture
(A-2) a carbonyl compound reservoir
(B-1) a condensation reactor (aminal precursor)
(B-2) a water separator
(B-3) a first reaction stage
(B-4) a final reaction step
(C-1) a phase separator
(C-2) a (single or multi-stage) extraction stage
(C-3) a (single or multi-stage) extraction stage
(C-4) a (single or multi-stage) extraction stage
(C-5) a multi-stage extraction stage
(C-6) a multi-stage extraction stage
(C-7) a water evaporator
(D) a processing stage consisting of
(D-1) a washing stage
(D-2) a security neutralization level or a basic ion exchanger
(D-3) a first distillation stage
(D-4) a final distillation stage
(E) a further processing stage consisting of
(E-1) a washing stage
(E-2) a security neutralization level or a basic ion exchanger
(E-3) a first distillation stage
(E-4) a final distillation stage
(Z-1) a collection container for a first process product
(Z-2) a collection container for another process product
(Z-3) a collection container for waste water.

The reference symbols A-Z denote the process stages to the following standing and reference is made in the examples.

The equipment of the reaction part (B) corresponds to the status of the technique. Both the first reaction stage (B-3) and the second Reaction stage (B-4) can consist of a single or of several Series reactors exist. To maintain a de defined residence time and temperature spectrum and also for the defi ned feeding of mass flows to the reaction agitators and / or columns connected in series proven reactors.

The extraction stages (C-2), (C-5) and (C-6) are usually as multi-stage extractors. While in the steps (C-3) and (C-4) limited and given even in single-stage execution if sufficient results can be achieved, the procedure is followed rensstufe (C-5) basically in a multi-stage extractor carried out, as well as the possibly subsequent procedure level (C-6).

The distillation stage (C-7) is a device with which is the aqueous phase of the system or a partial stream of water phase are removed by distillation at a suitable point can.

The distillation stage (C-7) is when the inventive method is carried out Process required to bring in the formaldehyde and the water formed in the condensation reaction from the closed eject its catalyst cycle, provided that a corresponding The amount of water cannot be separated using the water separator can, because the procedure without including an aminal precursor (B-1) a water separator (B-2) or because at least one  Partial amount of formaldehyde only after the aminal stage for example in process step (B-3) is added.

Process stage (C-7) is also required if the reac tion and rearrangement levels (B-3) and / or (B-4) for another, preferably at a higher molarity in the aqueous phase is processed as in the extraction stage (C-5) and optionally in the Level (C-6). The amount of water withdrawn for this purpose must be Catalyst circuit can be added again at a suitable point.

The distillation stage (C-7) is also required when in the extract tion stages (C-4) and / or (C-3) and / or (C-2) and / or the phases Scheider (C-1) is operated at a higher molarity than in the reak tion part of the procedure.

The water distilled off in the distillation stage (C-7) becomes, if it not to compensate for that introduced with the formaldehyde and that water formed in the condensation reaction is discharged, internally added again at a suitable point.

The optional washing stages (D-1) and (E-1) exist at least in each case from a mixer-separator unit, preferably from a 3- to 5-stage countercurrent extractor.

The process partial products are contained in these washing stages the organic phases with water from traces of acid free.

The washing liquid is preferably the internally revered used part of the distillate of the distillation stage (C-7). The distillate contaminated with hydrophobic solvent and arylamine is ideal for use in washing stages (D-1) and (E-1). If the amount of distillate available is not sufficient for Operate the washing stages, the amount of distillate may be egg be increased for this purpose.

The resulting wash water usually has a lot of ge lower acid concentration than the aqueous phases of the actual Chen catalyst circuit so that they can easily control the Molarity can be used in the sense of a lowering.

The wash water of the washing stage (D-1) is preferably in front of (C-4) recycled the aqueous circuit. The wash water of the wash stage If necessary, (E-1), preferably before (C-5), in the aqueous circuit run recycled.

The use of washing stages (D-1) and (E-1) enables a practical quantitative circulation of the acid used. This will also the use of expensive acids such as methanesulfone acid economically attractive. In turn, methanesulfonic acid enables because of their significantly lower corrosion resistance compared to hydrochloric acid the use of inexpensive materials in the apparatus of the inventive method. The use of the washing stages (D-1)  and / or (E-1) when carrying out the method according to the invention is therefore preferred.

The work-up stages (D) and (E) serve to separate the polyamine fractions, which are obtained as distillation residues and as process products ( 11 ) and ( 16 ) in the tanks (Z-1) and (Z-2) who are isolated and who Recovery of hydrophobic solvent and starting arylamine as a distillate.

It has proven to be advantageous to the distillation stages mentioned organic phases prior to their working up by distillation free traces of acid.

In general, this happens in the security neutralization levels (D-2) and (E-2) by reaction with basic substances, for example with dilute sodium hydroxide solution in excess in a mixer the existing process stage (D-2) or (E-2). The result aqueous phases are separated and in the waste water tank (Z-3) collected.

If the respective organic phases previously the washing stages (D-1) or (E-1) have passed, the security may, if necessary talization stage (D-2) or (E-2) are omitted or a basic ion dew sher can take their place.

Then the organic phases freed from traces of acid enter the distillation stages of the work-up parts (D) and (E).

In the case of the simplest implementation of the method according to the invention rens, it is sufficient both in the processing stage (D) and in the Processing stage (E), the distillation as a single-stage distillation lead because the accruing essentially from hydrophobic Lö distillates and starting arylamine are sufficient for their reuse.

As a rule, however, it is expedient and therefore advantageous given if necessary, distillation in the work-up stages (D) and / or (E) to be carried out in two stages.

Also for energetic reasons, it is advantageous in one or in the processing stages, the distillation as at least two stages to carry out stillation, a first fraction being used as the distillate, containing polyamine and starting arylamine depleted hydrophobic solvent and a final fraction containing Po Free from lyamine and depleted of hydrophobic solvent gangsarylamin.

For the implementation of the method according to the invention, it has proven to be Proven appropriately, not in the acidity of the aqueous phases Percent by weight, but rather the number of ammonium salt equivalents in one of the non-protonated amine fractions characterize reduced unit volume of the aqueous phase.  

By this always related to a degree of protonation of 100% The acidity can be administered independently of the changing aminge halt, which is about solution equilibria in the individual from the aq phase that has been completed, who is represented the.

This defined "molarity" is an important guide of the he method according to the invention and is depending on the respective from form of the underlying management - here product-related - separation gave in a wide range on the water content of the aqueous Phase controlled and varied in a targeted manner.

It may also be advantageous within one embodiment the individual process stages passed through by the aqueous phase to operate with different molarity in the aqueous phase, in that of the aqueous phase between the individual stages of water gene or is supplied.

In the reaction part, the molarity is an important reaction parameter and therefore depends on the reak produced as the reaction target tion product. The methods of the prior art can be used here get dressed by.

The molarity of the aqueous phase in stages (B-3) and / or (B-4) is generally higher than or equal to the molarity of the aqueous phase ( 08 ) fed to extraction stage (C-5). For the optimization of the extraction stage (C-5), molarities <3 are preferred, higher molarities are possible, but less preferred.

The optional downstream extraction stage (C-6) can be used both with the molarity of the aqueous phase ( 17 ) leaving the extraction stage (C-5) and with the higher molarity of the aqueous phase ( 18 ) which may have passed through the water distillation stage (C-7) ) operate. If the particular course of the process permits, the extraction stage (C-6) which may be connected downstream is preferably carried out at the molarity of the aqueous phase ( 17 ) leaving the extraction stage (C-5).

The molarity of the aqueous phases in the phase separator (C-1) and in the extraction stages (C-2) to (C-4) is in principle largely independent of those in the reaction part (B-3), (B-4) on the one hand and the Extraction stage (C-5), on the other hand, preferably uses molarities of the aqueous phases. It can be set to a higher or lower level using the water distillation stage (C-7) and the use of the concentrated flow ( 18 ) or the water distilled off. It is generally advantageous to set molarity values in stages (C-1) to (C-4) which are in the range between the generally higher molarity in the reaction part and the molarity in the extraction stage (C-5).

Molarity is important for process stages (C-1) to (C-4) Control parameters and can therefore, depending on the embodiment, Isolation  Gift and target product, values in the entire technically possible work accept area.

This working area is technically limited on the one hand due to the increasing tendency of the amine salts to crystallize increasing concentration, especially with high degrees of protonation, and on the other hand by the increasing mutual solubility of the Phases into each other.

At the bottom, this area is economically limited by the decrease acidity and thus the quantitative decrease of the separating line stung, d. H. with excellent qualitative separation performance and technically problem-free, is an increasingly larger volume with decreasing molarity on aqueous phase required for the separation of a given amine amount.

Generally, in the case of aniline and formaldehyde as the starting compounds and the corresponding polyamine mixtures as a reak tion products worked at molarities up to 6, preferably from 0.5-4.5 and temperatures up to 120 ° C under the system's own pressure.

Another important criterion for the characterization of the aqueous Pha sen and optionally the control of the process according to the invention rens is the degree of protonation, with the help of which the ratio of acid equivalents to arylamine equivalents in the aqueous streams is expressed.

It results from the equilibrium between organic and aqueous phase, with multi-stage countercurrent extracto primarily between the added organic phase and the result render aqueous phase.

It can be lowered by adding arylamine to an aqueous phase will. By balancing with an organic phase The degree of protonation can be based on their arylamine content lowers as well as be raised.

For example, in the extractor (C-6), the degree of protonation of the resulting aqueous phase ( 19 ) can be increased in a targeted manner by using an extraction agent depleted in arylamine. When using a practically arylamine-free hydrophobic solvent, as can be obtained in two-stage distillation in the work-up stage (E), it is entirely possible to set degrees of protonation up to 100% in ( 19 ).

In the simplest case, the method according to the invention becomes a reaction operated partly with the degree of protonation as an upper limit, which is in the Extraction level (C-5) at the specified preferential conditions poses. It is possible at any time by adding arylamine or arylamine-rich organic phase the degree of protonation in the aq to lower the phase and preferably before entering the extraction level (C-5) or, if necessary, to a limited extent in the Raise extraction level itself. The possibly after  switched extraction stage (C-6) is in such a process implementation not necessary.

If the use of an aqueous phase with a higher degree of protonation is advantageous for the chemical reactions in the reaction part or in one of the preceding extraction stages (C-2) to (C-4), the aqueous phase ( 19 ) or a corresponding portion in a downstream extraction stage (C-6) of an organic phase ( 24 ) which, in addition to hydrophobic solvent, has a lower arylamine content than the organic phase ( 12 ) used for the extraction in stage (C-5), so that as a result of equilibrium an aqueous phase ( 19 ) with a higher degree of protonation results than in ( 17 ).

At higher polyamine contents in the organic phase ( 13 ), which is produced by distillation, a total distillate depleted in arylamine already results in one-stage distillation, with which a limited increase in the degree of protonation can be achieved in a subsequent extraction stage (C-6).

As a rule, however, it is more effective to carry out the distillation in the working-up stage (E) at least in two stages and, for the formation of the organic phase ( 24 ) used in the downstream extraction stage (C-6), preferably the first distillate fraction ( 14 ) to use.

The further description of the method according to the invention and its Implementation takes place primarily using the example of the particularly preferred Production and integrated fractionation of polyamine mixtures, such as they are formed in the reaction of aniline with formaldehyde. The The terms aniline and formaldehyde are therefore used in typically representative of the terms starting arylamine, too Starting arylamine mixtures and carbonyl compound. The different Chen separation principles of the inventive method are about based on the reaction products of aniline with formaldehyde described.

First of all, a uniform primary polyamine is produced mixed by reacting aniline with formaldehyde and the umla of the precursors formed in the presence of acidic catalysts the final stages of the diamino-diphenylmethane and its higher-nucleus Homologues. At least in the last reaction stage is the catalyst usually a strong protonic acid, which in the form of an aqueous solution solution of their ammonium salts and after the rearrangement is complete via the extraction stage (C-5) in the form of an aqueous solution of its Ammonium salts are recovered and recycled.

It is irrelevant to the method according to the invention whether the primary action of arylamine with formaldehyde in an upstream separate Process stage, in the absence of catalyst in the absence or in the application of hydrophobic solvents and, if necessary, under Ab separation of the formed and the introduced with the formaldehyde Water takes place.  

It is also irrelevant whether the addition of the aqueous catalyst solution total in the first relocation stage or in succession in Partial quantities are added to the individual rearrangement stages.

If necessary, the first acidic rearrangement step can also be done with the help an acidic fixed bed catalyst are carried out so that the zu administration of the aqueous catalyst solution only in a second Stage to complete the rearrangement reaction.

The reaction conditions observed in the reaction section in particular orient with regard to the residence time spectrum, temperature profile and pressure the state of the art and the knowledge to generate a Reaction product mixture of certain composition and Be creativity.

The fully reacted reaction mixture ( 01 ) leaving the last reaction stage (B-4) contains the isomeric polyamines and varying amounts of their higher-core homologues, excess starting arylamine, acidic catalyst, water and, if appropriate, hydrophobic solvent.

In addition, the fully reacted reaction mixture ( 01 ) can contain varying amounts of incompletely rearranged reaction intermediates depending on the reaction procedure, for example of the aminobenzyl arylamine type or the usual condensation by-products, some of which are known in the art, for example of the N-methyl diamino-diphenylmethane type.

The molarity in the aqueous phase of the fully reacted reaction mixture ( 01 ) can take on values between 0.5 and 6.0, for higher degrees of protonation even higher values if necessary. In the methods of the prior art, the molarity is generally <3, in particular if the water formed in the condensation reaction and the water introduced, if appropriate, with the formaldehyde has been separated off, for example, in an upstream aminal stage.

The degree of protonation in the aqueous phase of the fully reacted reaction mixture ( 01 ) can assume values of up to 100% on one side and up to less than 15% on the other side of the scale. In the methods of the prior art practiced, degrees of protonation between 15% and 75% are generally achieved.

The polyamine content in the aqueous phase of the fully reacted reaction Mixtures can be up to 90% of the arylamine content.

Therefore, it may be necessary to use the fully reacted reaction gene to modify so that the two - phase nature of the system in the subsequent process stage (C-1) is adequately guaranteed and that moreover a sufficient density difference between the Phases is given.

The polyamine content can be "diluted" and adjusted to a desired low value by admixing aqueous phase depleted in polyamine from quantity stream ( 17 ) and / or from the quantities present ( 18 ) and ( 19 ).

A low degree of protonation in the fully reacted reaction mixture can be specifically raised, a high degree of protonation be lowered.

The molarity in the fully reacted reaction mixture can be added of the aqueous phases mentioned both raised and within limits be lowered. Regardless of this, there is the option of Add water to lower the molarity or in return by water removal by distillation towards the end of the last rearrangement stage in Reactor (B-4) or immediately afterwards to increase the molarity and on set a desired value.

By adding organic phase to ( 01 ), containing hydrophobic solvent and optionally starting arylamine and optionally small amounts of polyamine, depending on the content of the added organic phase of starting arylamine, the polyamine content in the aqueous phase of the resulting two-phase mixture can be reduced and depending on the degree of protonation of the fully reacted reaction mixture the degree of protonation in the aqueous phase of the resulting two-phase mixture can be raised or lowered.

The two-phase reaction mixture ( 01 ), optionally modified in the manner described above, is separated in a phase separator into an organic phase ( 02 ) and an aqueous phase ( 03 ).

The organic phase ( 02 ) is at least partially, preferably in total, if appropriate after the addition of further polyamine-containing organic mass flows as a mass flow ( 23 ) in a preferably multi-stage extraction stage (C-2) to an aqueous phase, which at least consists of portions of the Mass flow ( 17 ) and / or the optionally present mass flows ( 18 ) and / or ( 19 ) is formed and the amount is such that the polyamine contained in the supplied organic phase largely, if appropriate practically quantitatively, into the aqueous phase ( 04 ) is transferred.

The organic phase ( 05 ) which is depleted in polyamine and possibly largely freed from the polyamine and which results in stage (C-2) can be recycled both into the reaction process and as - at least part of - in the extraction stage (C-4) as Extractant used flow rate ( 06 ) can be used. At least in the case of at least partial use as an extracting agent, the residual polyamine content in ( 05 ) is preferably <1% by weight. When recycling the entire mass flow ( 05 ) into the course of the reaction, higher residual levels of polyamine are also permissible or possibly useful, so that the extraction stage (C-2) is carried out in relation to the residual content of polyamine in the organic phase ( 05 ) the respective further use.

A simple and therefore preferred embodiment is the recycling of the organic phase ( 05 ) into the course of the reaction. If the organic phase is already used in the reactor (B-1), ie in the acid-free range, it is advantageous to reduce the mass flow ( 05 ) over a washing stage according to (B-1). This process is unnecessary when the quantity flow ( 05 ) is recycled into the reactor (B-3) and / or (B-4).

In a first variant of the process according to the invention, the aqueous phase ( 04 ) resulting in the extraction stage (C-2), together with the aqueous phase ( 03 ) separated in the phase separator, is countered in a further extraction stage (C-4) to the organic phase ( 06 ) leads.

The organic phase ( 06 ) contains hydrophobic solvent, usually starting arylamine and optionally polyamine.

The organic phase ( 06 ) is generally formed from at least portions of the first distillate fraction ( 09 ) and, if appropriate, from starting arylamine from (A-1) and / or from portions of the second distillate fraction and / or from a substream of the subsequent extraction stage (C-5) leaving organic phase ( 13 ).

Polyamine of the type contained in the stream ( 13 ) as a component of the organic phase ( 06 ) is preferred.

It is also possible to compile the organic phase ( 06 ) with the use of at least partial amounts of the organic phase ( 05 ), provided the residual polyamine content is low enough to meet the purity requirements of the second process product ( 16 ).

The implementation of process step (C-4) can be done in one step Mixing the phases and subsequent phase separation in a Mi shear separator unit or multi-stage countercurrent in one Extractor can be performed.

The one-stage execution of process stage (C-4) can be effective and therefore particularly in combination with the further process stage (C-3), as described in variants two to four, particularly with regard to the first process product ( 11 ) be preferred form of carrying out the method according to the invention. In any case, the multi-stage version of the process stage (C-4), which is particularly preferred for this reason, is more efficient, in particular with regard to the second partial process product ( 16 ).

The organic phase used in (C-4) is dimensioned such that the amount of polyamine added is distributed in a controlled manner to the resulting organic phase ( 07 ) and the resulting aqueous phase ( 08 ) (quantitative fractionation). The phase ratio in stage (C-4) is therefore an important control parameter.

Irrespective of this, the individual components of the polyamine mixture are divided into the resulting aqueous phase ( 08 ) and the resultant organic phase ( 07 ) under the conditions of the process according to the invention with a surprisingly high selectivity, so that the resulting product fractions have a different, possibly have a composition that differs significantly from the polyamine mixture introduced (qualitative fractionation).

This manifests itself in the fact that the preferred aniline-formaldehyde condensation products of a polyamine component present in two or more isomeric forms in the reaction mixture generally contain the orthoisomeric form (s) in the organic phase leaving the separation stage (C-3) Phase ( 03 ) is (are) relatively enriched; for example 2,4'-diamino-diphenylmethane relative to 4,4'-di aminodiphenylmethane. Conversely, the resulting aqueous phase ( 04 ) is relatively poor in the 2,4'-isomer, while the 4,4'-isomer is relatively enriched.

Are several "ortho isomers" present in the starting polyamine, e.g. B. 2,2'- and 2,4'-diamino-diphenylmethane, then the "ortho-richer"2,2'-isomer in the organic phase ( 03 ) compared to the "ortho-poor ren 2,4'- Isomers more enriched, the latter of which in turn is relatively enriched compared to the "still ortho poorer"4,4'-isomer.

The first in those formed by aniline-formaldehyde condensation isomeric diamino-diphenylmethanes effect was purely empirical-descriptive with the criterion of ortho and para substitution linked. The character derived from it Rization of the process products as "ortho rich" and "ortho poor" is there at relative and is indicated by the term "degree of ortho substitution" presses.

The "ortho degree of substitution" is the ratio of orthoständi gene group-methylene group relations to the total number of all Amino group relations defined. With this term can be practically table capture all isomer separations in the polyamines that from Arylamines, whether or not substituted, with carbonyl compounds in aqueous acidic medium.

Surprisingly, the same enrichment and depletion was now fekt - ordered by degree of ortho substitution - also for the good characters standardized and analytically detectable isomeric trinuclear compounds of aniline-formaldehyde condensation.

The same applies to the separation of the isomers from the condensation product formaldehyde with aniline and diaminoaryl compounds and their substituted, especially alkyl-substituted derivatives.

The polyamine mixtures mentioned so far have, due to their origin position, one amino group per aryl unit, which is practically only are ortho and / or para to methylene groups.

Here, within a group of isomeric compounds, in general those with the higher degree of ortho substitution, are enriched compared to the isomers with a lower degree of ortho substitution in the fractionation in the organic phase ( 07 ).

When fractionating technical polyamine mixtures by mixing condensation of mono- and diamino-aryl compounds with formaldehyde or generally carbonyl compounds were obtained in addition to the pure separation of isomers, another surprising Se found selectivity.

Contain or can contain polyamine mixtures of the substance class mentioned contain components in which at least one aryl nucleus per molecule carries more than one, usually two amino groups. This com Components can be the preferred components of the polyamine mixture without being the main products in terms of quantity.

The term is used to better characterize such components "Amino substitution level" is used to primarily count the number the amino groups of a component in relation to the number of aryl is marked.

For example, for aniline and its condensation products Formaldehyde this expression is always 1.0, for phenylenediamine and its Condensation products always 2.0. For pure mixed condensates the value for the diphenylmethane isomers is 1.5 and for the higher ones some homologues values between <1.0 and <2.0. With statistical ver Use of the term degree of amino substitution for characterization Technical polyamine mixtures also result in values between between 1.0 and 2.0.

When fractionating polyamine mixtures with components with egg nem degree of amino substitution <1.0 it has now been found that the com components with a higher degree of amino substitution in the actual Chen separation step resulting aqueous phase relatively enriched become, the stronger the greater the degree of amino substitution.

Regardless of this, the separation according to the ortho substituent is also here degree of effectiveness.

The method according to the invention thus also opens up for this sub punching class the possibility of the production form of the raw materials (Amine stage) and the use form of the end products (isocyanate stage) to decouple, so that a separate optimization of both stages facilitate tert is up to the production of completely new isocyanate mixtures.

These "achievements" are supplemented by another selectivity criterion rium, which is used for the fractionation of technical polyamine mixtures especially those with higher nucleus homologues was found and concerns the "core" of the polyamine mixtures.

The term "core" is primarily the number of aryl units component of an aromatic polyamine mixture. In a broader sense, the concept of core is used to mean for one of numerous components, with an individual exact core nity, existing polyamine mixture statistically a core of the Express overall mixture.  

Particularly surprisingly, it has now been found in the fractionation of polyamine mixtures with higher-kernel proportions, especially in the fractionation of technical mixtures of aniline-formaldehyde condensates, that the higher-kernel components in the organic phase ( 07 ) leaving the fractionation stage (C-4) are deliberately so can be relatively enriched as well as relatively enriched, depending on the molarity of the aqueous phase in the extraction stage (C-4).

A high molarity of the aqueous phase in (C-4) within the specified molarity range leads to a relative depletion of higher-nuclei components in the organic phase ( 07 ) and accordingly to a relative enrichment in the aqueous phase ( 08 ).

A low molarity of the aqueous phase in (C-4) within the specified molarity range leads to a relative accumulation of higher core components in the organic phase ( 07 ).

The surprising finding can be expanded and specified be that the relative enrichment and depletion also within the higher robust homologues takes place among themselves. For example, in a technical mixture of diamino-diphenylmethane in one Fraction the trinuclear components versus the dual-core components relative enrichment or depletion, a relative enrichment or depletion is also protection of quad-core components against triple-core components, d. H. an even stronger relative enrichment and depletion, found the same from five-core components to four-core components etc.

From this and from the simultaneous and always in the sense of a relative increase in the "ortho-degree of substitution" in the organic phase ( 07 ) isomer separation, there are numerous possibilities, starting from known and easily accessible polyamine mixtures via the process according to the invention to make them less accessible or completely new, because according to the prior art previously inaccessible, polyamines and thus polyisocyanates. This applies in particular to products from the diamino and diisocyanato-diphenylmethane series and very particularly to polyamine and polyisocyanate mixtures with an extremely high proportion of higher-core components.

The enrichment or depletion generally becomes more selective with increasing Degree of protonation in the aqueous phase of the separation stage (C-4).

In addition, the method according to the invention proves to be of general effectiveness also on other structurally similar polyamines.

When condensing arylamines with carbonyl compounds numerous incompletely rearranged intermediate connections and secondary products occur.

Most of these connections are usually subject to the Frak tion of the polyamine mixtures containing them one of the resulting fractions, so the separation effect  and fractionation can be used. If necessary, derar products enriched and recycled or recycled in this way be smuggled.

With the described one-step implementation of the process step (C-4) can already be a considerable one in terms of qualitative fractionation and sufficient separation performance can be achieved in numerous cases. This applies in particular to the enrichment in the organic phase enriched components, if any more, the separation effect reinforcing process step (C-3) is run.

The depletion of these components in the associated aqueous phase ( 08 ), on the other hand, is limited in the one-stage execution of process stage (C-4) to the equilibrium values that arise and in a one-stage execution of process stage (C-4) with regard to that second process product are not further strengthened.

The qualitative separation performance for the polyamine fraction contained in the resulting aqueous phase ( 08 ) can be significantly improved and possibly maximized by extracting in a multi-stage extraction stage (C-4) in countercurrent with an organic phase ( 06 ) containing hydrophobic Solvent, where appropriate, starting arylamine and optionally polyamine, the latter before preferably on the type and composition of the polyamine fraction separated in the subsequent extraction step (C-5).

Both in the one-stage and in the multi-stage version of process stage (C-4), the amount of the organic phase ( 06 ) supplied is adjusted and its composition is adjusted so that the polyamine supplied is in a wide range based on the resulting organic Phase ( 07 ) and the resulting aqueous phase ( 08 ) are distributed in a controlled manner in terms of quantity and the different composition of the polyamine fractions contained in the two phases is specifically set within the limits of what can be achieved in process step (C-4).

According to the first variant, the organic phase ( 07 ) is worked up by distillation in order to obtain and isolate the product fraction contained therein, with its composition, which may be very different from the actual condensation product.

The organic phase ( 07 ) leaving the extraction stage (C-4) contains, inter alia, small amounts of acid, generally and depending on the process parameters in the extraction stage (C-4) between 0.01 and 0.5% by weight. %, which are advantageously removed before the distillative processing of the mass flow ( 07 ).

In the simplest case, this is done by neutralization with excess gene, dilute aqueous bases, for example dilute sodium lye. However, washing out the acid or its acid is preferred Ammonium salts from the organic phase with water, so that against if necessary, only remaining traces due to contact with diluted Sodium hydroxide solution or with the help of an ion exchanger.  

The wash water used is switched on with the water ver dampfers (C-7) withdrawn from the aqueous acid cycle and after this Go through the washing step (s) together with the acid on procedural added appropriate place again.

The organic phase ( 07 ) is, optionally after passing through the acid washing stage (D-1) and / or the security neutralization stage (D-2), into a preferably two-stage distillation stage (D-3), (D-4).

In the first distillation stage (D-3), a distillate ( 09 ) is separated off, which comprises the main amount, preferably almost the total amount, of the hydrophobic solvent contained in ( 07 ) in addition to part of the starting arylamine contained therein. In general, the distillate contains <50% starting arylamine, preferably 15-30%.

In the last distillation stage (D-4), the remaining starting arylamine, optionally in addition to the remaining amount of the hydrophobic solvent, is separated as distillate ( 10 ) from the first partial product ( 11 ) obtained as a distillation bottoms and collected in the process product tank (Z-1) . In general, the distillate ( 10 ) contains <50% hydrophobic solvent, preferably <30%, optionally in (D-4) as the distillate ( 10 ) a starting arylamine largely freed from hydrophobic solvent is obtained.

The corresponding second part of the process is in the aqueous phase ( 08 ) leaving the extraction stage (C-4).

The resulting in the extraction stage (C-4) aqueous phase ( 08 ), optionally after adding water to lower the molarity and / or starting arylamine to lower the degree of protonation, the multi-stage extraction stage (C-5) and supplied with the aid of organic phase ( 12 ) extracted in countercurrent at 80-110 ° C. The polyamine is largely converted into the organic phase ( 19 ) in exchange for starting arylamine.

The molarity of the aqueous phase used in (C-5) is usually <3, preferably <2.5.

The degree of protonation of the aqueous phase used in (C-5) is in generally <60%, preferably from 25% to 50%.

The extractant ( 12 ) used is a mixture of hydrophobic solvent and starting arylamine, which is generally composed of the distillate fractions of the work-up stage (E) and starting arylamine from storage container (A-1).

The weight ratio of starting arylamine to solvent in ( 12 ) is generally between 0.5: 1 and 3: 1, preferably between 1: 1 and 2: 1, depending on the molarity of the aqueous phase supplied.

The weight ratio of extractant ( 12 ) to aqueous phase is generally between 0.3: 1 and 3: 1, preferably between 0.7: 1 and 2: 1.

The organic phase ( 13 ) resulting in (C-5) is at least partially, optionally after passing through the washing stage (E-1) and / or optionally after removing traces of acid with dilute sodium hydroxide solution (E-2), the distillation stage (E 3) or the distillation stages (E-3), (E-4).

In the work-up stage (E), the distillation residue ( 16 ), which is collected as a second partial product in the process product tank (Z-2), is separated off.

The distillation part of the work-up stage (E) can consist, for example, of a single-stage evaporator (E-3) which, in addition to the distillation residue ( 16 ), provides a distillate ( 14 ).

In this case, the distillate ( 14 ) contains, in addition to starting arylamine, the entire hydrophobic solvent from ( 13 ) and, after addition of starting arylamine from tank (A-1), is used again as extracting agent ( 12 ).

In the particularly preferred case of the condensation of aniline and formaldehyde in the reaction part to the corresponding polyamines and consequently the use of aniline as the starting arylamine, the extraction stage (C-5) results in an aqueous phase ( 17 ) with a residual polyamine content of generally <5% by weight, preferably <3% by weight and a degree of protonation of generally 45% to 70%, preferably 50% to 65%.

In the simplest case of the first variant, the aqueous phase ( 17 ) containing the rearrangement catalyst is partially recycled into the reaction part, optionally partially added to the fully reacted reaction mixture ( 01 ) after the rearrangement has ended and before entering the phase separator (C-1), and partially used in the extraction stage (C-2).

In many cases, the reaction conditions with regard to the primary reaction product for the use of catalyst require a higher molarity than is obtained in the aqueous phase ( 17 ).

In principle, the extraction in stage (C-5) can also be carried out at one higher molarity than in the specified preferred range be performed. With increasing molarity in the reaction part it is ever but more advantageous, the two process sections with respect to their Mo larity by adding water independently ren.

In this case, the aqueous phase ( 17 ) is at least partially removed by distillation in the evaporator stage (C-7) by distillation prior to its reuse to form the aqueous phase ( 18 ) with a correspondingly higher molarity for use in the reaction part and / or in ( C-2), optionally in a mixture with aqueous phase ( 17 ).

The amount of water withdrawn from the aqueous phase must correspond to the aqueous Catalyst cycle at a suitable point, but at the latest before How the aqueous phase enters the extraction stage (C-5) again be performed.

The distillation stage (C-7) must be run if this at the Condensation reaction formed, for example with the form Water introduced as aldehyde as an aqueous formalin solution was not present their place and / or in another way, for example via the Schei the (B-2), is discharged and / or if the recycled aqueous Phase of their reuse in the reaction part with a higher one Molarity is used as that resulting in the extraction stage (C-5) corresponding molarity.

In those cases where a higher degree of protonation than that which arises when leaving the extraction stage (C-5) is advantageous and / or necessary for the further use of the aqueous phases ( 17 ) and / or ( 18 ), the aqueous phases ( 17 ) and / or ( 18 ) at least partially counteracted in a downstream extraction stage (C-6) of an organic phase ( 24 ) which essentially consists of hydrophobic solvent and optionally starting arylamine with the proviso that the arylamine content is always smaller than in the organic phase ( 12 ) used in the extraction stage (C-5).

The organic phase ( 24 ) is essentially formed from at least part of the first distillate fraction ( 14 ). The arylamine content of the organic phase ( 24 ) is preferably <30% by weight, if appropriate the arylamine content can be from ( 24 ) to <3% by weight.

While the distillate from a one-stage distillation can be used to form the organic phase ( 12 ), the formation of the organic phase ( 24 ) for the optionally subsequent extraction stage (C-6) generally requires an at least two-stage distillation in the course of the work-up stage (E).

Only at higher polyamine contents in the organic phase to be worked up ( 13 ) do total distillates also arise in single-stage distillation, the arylamine deficit of which has a limited effectiveness as an extraction agent in a downstream extraction stage (C-6).

The resulting aqueous phase ( 19 ) in (C-6) has a higher degree of protonation than the aqueous phase used, optionally up to 100%. The amount of arylamine withdrawn from the aqueous phase ( 19 ) must be returned to the aqueous circuit at a suitable point, but at the latest before the aqueous phase re-enters the extractor (C-5).

The organic phase ( 25 ) resulting in (C-6) is correspondingly enriched in arylamine, but generally with a content of <1% is practically free of polyamine and is preferably used to form the organic phase ( 12 ).

Starting arylamine is fed to the reaction in addition to the aqueous phases ( 17 ) and / or ( 18 ) and / or ( 19 ), in particular via the recycled organic phase ( 05 ) and / or the distillate fractions ( 10 ) and ( 09 ) and / or fresh aniline from the storage container (A-1).

The variety of uses in which the catalyst and the starting arylamine can be fed to the reaction also allow the chemical reaction parameters in one wide range to vary flexibly and for a wide range of products to optimize.

Leave with this first variant of the method according to the invention already considerable separation performance in the fractionation of Po achieve lyamine mixtures in combination with their manufacture and number solve rich separation problems satisfactorily.

Particularly in the second process sub-product ( 16 ), the depletion of the components enriched in the first sub-product ( 11 ), depending on the choice of process parameters, can be varied in a targeted manner and, if appropriate, can be maximized in the case of a multi-stage execution, so that the corresponding components may be almost completely eliminated the second partial process product ( 16 ) are separated.

As a result, these components can be found almost completely in the first partial product ( 11 ) in enriched form. This relative concentration is, however, an upper limit when carrying out the process according to the first process variant, which is determined by the establishment of equilibrium in process step (C-4) between the supplied aqueous mass flow and the resulting organic phase ( 07 ) containing the first partial product ( 11 ). results under the respective process parameters.

Due to this one-sided limitation in the qualitative fractionation on the side of the first partial product ( 11 ), the second partial product ( 16 ) remains below the possible maximum in the quantitative fractionation, ie in the yield.

More efficient in this regard is a second variant of the method according to the invention, which differs from the first variant in that the organic phase ( 07 ) resulting in the method stage (C-4) is not fed directly to the processing stage (D) but at least as a partial amount (stream 20 ) previously in an upstream extraction stage (C-3) of an aqueous phase containing water, a strong acid in the form of its ammonium salts, starting arylamine and optionally small amounts of polyamine.

The low-polyamine aqueous phase is formed from at least a portion of the aqueous stream ( 17 ) and / or at least from portions of the streams ( 18 ) and / or ( 19 ) that may be present.

Process stage (C-3) is preferably carried out in several stages. Improved enrichment can already be achieved with a single-stage implementation, but only the multi-stage process enables the qualitative fractionation, ie the relative enrichment of the components contained in the first partial product ( 11 ), to be increased and, if necessary, maximized.

The aqueous phase ( 22 ) obtained in process stage (C-3) is fed to process stage (C-4).

With the same composition as in the first variant, the second partial product ( 16 ) results in an improved yield in terms of quantity.

The polyamine content of the resulting organic phase ( 21 ) is lower than that of the organic phase ( 20 ) used. For the more highly qualified first partial product ( 11 ) separated off via process stage (C-3), this results in a higher specific energy expenditure when working up the organic phase ( 21 ) in workup stage (D).

In a third variant, the organic mass flow ( 07 ) is fed to the workup via the extraction stage (C-3), as in the second variant. In contrast to the second variant, however, it is directed towards the polyamine-containing aqueous phase ( 04 ) from the extraction stage (C-2) or at least a subset of ( 04 ).

The relative enrichment of the corresponding components in the resulting organic phase ( 21 ) cannot be increased as much as in the second variant due to the establishment of distribution equilibria between the polyamine fractions contained in ( 04 ) and ( 21 ). However, the relative enrichment is considerably higher than in the polyamine fraction resulting from the first variant and the enriched polyamine is obtained in ( 21 ) at a comparable degree of enrichment with a significantly higher concentration than in the second variant.

In a fourth variant, the above-described procedures are combined with one another in such a way that in an at least two-stage, preferably multi-stage extraction stage (C-2) the organic quantity stream ( 20 ) first in the first stage from the point of view of the aqueous phase supplied, a low-polyamine stream, Consisting of at least a partial amount of flow ( 17 ) and / or ( 19 ), and at least partially in the second, optionally the last stage, the polyamine-containing aqueous phase ( 04 ) is counter-directed.

It may also make sense to add the aqueous phase not only to separate functionally, but the extraction stage (C-3) can also be separated into two stages, e.g. a Mi Scher separator unit for a first stage (C-31) and one more stage extractor for the second stage (C-32).  

In this procedure according to the fourth variant, the resulting organic phase ( 21 ) contains a polyamine fraction, the relative enrichment of which can be maximized if necessary, but with comparable enrichment compared to the second variant with a higher polyamine concentration which is favorable for the energy balance of the process.

Example 1 (variant 4)

30% aqueous formaldehyde solution (2.15 kg / h) with a mixture containing ortho-xylene, aniline and small amounts of polyamine and formed from the mass flow ( 05 ) (in a reactor consisting of two stirred tanks connected in series (B-1) 5.2 kg / h) and aniline (2.25 kg / h) at 30 ° C in the first and 45 ° C in the second stirred kettle for reaction.

In the subsequent separator (B-2) the aqueous phase is removed separates and collected as wastewater in the wastewater collection tank (Z-3).

The organic phase is mixed in a second reactor consisting of three stirred tanks (B-3) with a first portion of the aqueous Men genstromes ( 18 ) at 30 ° C and gradually brought up to about 90-95 ° C in the subsequent kettles .

In a further reactor consisting of four stirred tanks (B-4) the temperature under the system's own pressure gradually up to Raised 140 ° C.

After cooling to approx. 95 ° C., the fully reacted two-phase reaction mixture ( 01 ) is mixed with the washing water (approx. 1.5 kg / h), which, in the acid-free washing of the organic phase ( 05 ), is carried out in a three to five-stage washing stage (not shown), and then separated in the phase separator (C-1) into the organic phase ( 02 ) and the aqueous phase ( 03 ).

The organic phase ( 02 ) is counter-ent in the multistage extractor (C-2) of a second portion (2.9 kg / h) from the mass flow ( 18 ) ent. The resulting organic phase (flow 05 ) is washed with about 1.5 kg / h of water, which is removed from the distillate from the water evaporator (C-7), at about 60 ° C. and then the reactor (B-1) fed. The aqueous phase ( 04 ) resulting in the extractor (C-2) is fed to the second sub-stage (C-32) of the two-part extractor (C-3).

The aqueous streams ( 03 ) and ( 04 ) are fed together in a multi-stage extractor (C-4) to an organic phase (stream 06 ) (7.2 kg / h), which is formed from the main amount (6.3 kg / h) of the distillate stream ( 09 ) and a portion (0.9 kg / h) of the organic phase ( 13 ) obtained in the subsequent extraction stage (C-5).

The organic phase resulting in stage (C-4) (volume flow 07 ) is divided into two stages (C-31) (approx. 2 stages) and (C-32) (approx. 4 to 5- stage) counter to an aqueous phase which is formed by firstly in the first sub-stage (C-31) a third subset (1.6 kg / h) of stream ( 18 ) and in the second sub-stage (C-32) Volume flow ( 04 ) from extractor (C-2) is additionally fed.

The resulting organic phase in the extractor (C-3) (mass flow 21 ) is washed acid-free from adhering traces of acid (<0.02% by weight HCl) in a safety neutralization stage with excess 5% sodium hydroxide solution. The wastewater is collected in the wastewater collection tank (Z-3), the acid loss is compensated for by adding it from the outside at a suitable point.

The acid-free stream ( 21 ) is separated as stream ( 07 ) in a first distillation stage (D-3) into the distillate fraction (stream 09 ) (approx. 6.8 kg / h) containing aniline and xylene in a ratio of 1: 4.

In the second distillation stage (E-4), practically solvent-free (<1% by weight xylene) aniline is obtained as the distillate as a stream ( 10 ) (approx. 1.44 kg / h). As a distillation residue of (E-4) there remains a first polyamine fraction as a mass flow ( 11 ) (0.5 kg / h).

The aqueous phase (volume flow 08 ) resulting in the extraction stage (C-4) is mixed with the wash water of the acid washing stage (E-1) (approx. 2.3 kg / h) and then in the multi-stage extraction stage (C-5) extracted with the aid of flow ( 12 ) (13.5 kg / h), containing aniline and xylene in a weight ratio of 1.1: 1.0.

The resultant, largely polyamine-depleted (approx. 2.2% by weight polyamine) aqueous phase (stream 17 ) is removed by distillation in the water evaporation stage (C-7) by distillation (approx. 3.8 kg / h). The resulting concentrated aqueous phase (stream 18 ) is recycled in the specified amounts into process stages (B-3), (C-2) and (C-31).

From the organic phase (flow stream 13 ) obtained in the extraction stage (C-5), a partial amount (0.9 kg / h) is used to form flow stream ( 06 ) and is fed to the extractor (C-4).

The remaining part of the mass flow ( 13 ) is washed acid-free in the acid washing stage (E-1) with distillate from (C-7) (approx. 2.3 kg / h) and excess in a security neutralization stage (E-2) treated 5% aqueous sodium hydroxide solution.

In the one-stage distillation stage (E-3), hydrophobic solvent and aniline are separated as a distillate mixture (stream 14 ), with a partial amount (0.5 kg / h) of stream ( 09 ) and with fresh aniline (approx. 2.65 kg / h) added and recycled as extractant (volume stream 12 ). A second polyamine fraction (3.13 kg / h) remains as a distillation residue as a mass flow ( 16 ).

In phosgenation under standard conditions, it was found that, based on the isocyanates derived from the primary product as standard, the isocyanates derived from the first partial product ( 07 ) had higher values in the hydrolyzable chlorine functions than the standard during the isocyanates derived from the second partial product ( 12 ) the chlorine functions are extremely low. This applies both to the distilled monomer isocyanate, which can be obtained with simple distillation as <99% 4,4-diisocyanatodiphenylmethane, and to the polymer isocyanates obtained as the distillation residue.

An equally surprisingly favorable result with regard to hydrolyzable chlorine functions results for the nuclear hydrogenated isocyanates derived from the second partial product ( 12 ), in particular for the bis- (4-isocyanato-cyclohexyl) methane, regardless of whether the second partial product as a whole or a distilled-off two-core fraction is subjected to nuclear hydrogenation.

Claims (11)

1. A process for the preparation with integrated fractionation and / or purification of aromatic polyamine mixtures by reacting starting arylamine or starting arylamine mixtures with car bonyl compounds, in particular formaldehyde, in the presence of acidic catalysts and in the presence of water at least in the last part of the rearrangement reaction and, if appropriate, with circuitry a separate "aminal stage" for the formation of N, N'-disubstituted condensation products in the absence of acidic catalysts and optionally in the presence of hydrophobic solvent in one or more stages of the reaction, which is characterized in that

• a) the fully reacted
• b) optionally after addition of starting arylamine and / or water and / or a strong acid in the form of its ammonium salts of starting arylamine and optionally polyamine, which are preferably in the form of the recycled aqueous phase ( 17 ) and / or ( 18 ), and / or ( 19 ) is used, and
• c) optionally after addition of hydrophobic solvent, which may contain chary starting arylamine and / or polyamines,
• d) two-phase reaction mixture ( 01 ) in a separator (C-1) on separates into an organic phase ( 02 ) and into an aqueous phase ( 03 ) and the organic phase ( 02 ) at least partially in an extraction stage which preferably works in several stages (C -2) counteracts an aqueous phase containing essentially water, a strong acid in the form of its ammonium salts, starting arylamine and optionally small amounts of polyamine and formed at least from subsets of the stream ( 17 ) and / or the streams which may be present ( 18th ) and / or ( 19 ), the amount is such that the polyamine contained in the organic phase ( 02 ) fed largely, possibly practically quantitatively into the resulting aqueous phase ( 04 ), which is carried out
• e) optionally via the extraction stage (C-3)
• f) the extraction stage (C-4) and the resulting, largely free of polyamine organic phase ( 05 )
• g) optionally at least partially via the extraction stage (C-4) or
• h) if necessary, at least in part initially via the extraction stage (C-4) and subsequently at least in part via the extraction stage (C-3)
• i) at least partially recycled at a suitable point or in partial streams at several points in the reaction sequence, but at the latest in the reaction mixture before it enters the separator (C-1), and the aqueous phase ( 03 ) together with that in the extraction stage (C-2) resulting and optionally via (C-3) led aqueous phase initially in the one or preferably multi-stage extraction stage (C-4) of an organic phase ( 06 ) containing hydrophobic solvent, usually starting arylamine and optionally Polyamine, which is measured in terms of quantity and its composition is such that the polyamine fed to process stage (C-4) is controlled in a wide range on the resulting organic phase ( 07 ) and the resulting aqueous phase ( 08 ) Way distributed in terms of quantity and the different composition of the resulting polyamine fractions is adjusted and the resulting organic phase ( 07 )
• k) optionally at least partially via the extraction stage (C-3) or
• l) if appropriate after separating off a portion of the extraction stage (C-2) or
• m) if appropriate, at least partially via the extraction stage (C-3) and separating off a partial quantity supplied to the extraction stage (C-2) before and / or after passing through the extraction stage (C-3) or
• n) optionally at least partially via an extraction stage (C-3) consisting of the two sub-stages (C-32) and (C-32) and acting at least in two stages, and optionally with separation of a subset supplied to the extraction stage (C-2) before and / or after going through the extraction stage (C-3)
• o) in the course of the reaction before the end of the reaction, ie in the reactors (B-1) and / or (B-3) and / or (B-4), recycled and / or via a washing and / or neutralization step in one preferably, multi-stage distillation stage (D-3), (D-4) in a first distillate fraction ( 09 ), containing hydrophobic solvent and optionally starting arylamine, a second distillate fraction ( 10 ), containing starting arylamine and optionally hydrophobic solvent, and in a distillation residue ( 11 ), consisting essentially of a first polyamine fraction, and the aqueous phase ( 08 ) leaving the extraction stage (C-4)
• p) optionally after adding water and / or starting aryl amine
• q) in a multi-stage extraction stage (C-5) leads, in which cher, according to the principle of countercurrent extraction, the extraction of the polyamine from the aqueous phase supplied by means of an organic phase ( 12 ) containing hydrophobic solvent, starting arylamine and optionally small amounts of polyamine, and the resulting polyamine-containing organic phase ( 13 ) at least partially via a washing and / or neutralization stage (E-2) in an optionally multi-stage distillation stage (E) in at least one distillate fraction ( 14 ) containing hydrophobic solvent and Starting arylamine, and in a distillation residue ( 16 ), consisting essentially of a second polyamine fraction, and the resulting, largely polyamine-free aqueous phase ( 17 )
• r) optionally at least partially via a water evaporation stage (C-7) with the removal of water by distillation and formation of a mass flow ( 18 ) and / or
• s) if necessary at least partially via a downstream extraction stage (C-6) with the removal of amine and increasing the degree of protonation and formation of mass flow ( 19 )
• t) reused by partially returning the stream ( 17 ) and / or the streams ( 18 ) and / or ( 19 ) that may be present as a catalyst solution into the reaction and partially feeding the extraction stage (C-2) and a possibly remaining one The rest of the fully reacted reaction mixture according to b) and / or optionally the extraction stage (C-3).

2. The method according to claim 1, characterized in that one

• m) the aqueous phase ( 17 ) depleted in polyamine in the extraction stage (C-5) and / or the aqueous phase ( 19 ) depleted in arylamine in the extraction stage (C-6) at least partially before their further use in water Vaporization stage (C-7) removes a portion of the water by distillation and an amount of water which corresponds to the amount of water formed in the condensation reaction and, if appropriate, the amount of water introduced with the starting compounds, in particular the carbonyl compound, unless it is discharged by other means than waste water and an additional amount of still water is added to the aqueous circuit at a suitable point, but at the latest before the aqueous phase enters the extraction stage (C-5), preferably after passing through the washing stages (D-1) and / or (E-1) .

3. The method according to claim 1 and 2, characterized in that

• n) the resulting in the extraction stage (C-5) largely freed from polyamine aqueous phase ( 17 ) at least partially in a downstream extraction stage (C-6) counteracts an organic phase containing hydrophobic solvent and optionally starting arylamine, the amine content always being smaller than in the organic phase ( 12 ) used in the extraction stage (C-5) and the resultant, lower amine content (= higher degree of protonation) than the aqueous phase ( 19 ) used, at least partially in the course of the reaction, in particular in the first course of the reaction Rearrangement level (B-3).

4. The method according to one or more of claims 1 to 3, characterized in that
the resulting in the extraction stage (C-4) organic phase ( 07 ) at least partially as a mass flow ( 20 ) in the extraction stage (C-3) against an aqueous phase containing essentially water, a strong acid in the form of its ammonium salts starting arylamine and optionally small amounts of polyamine and formed at least from subsets of the volume flow ( 17 ) and / or the volume flows ( 18 ) and / or ( 19 ) which may be present, which are measured in terms of quantity and in their composition such that the step ( C-3) polyamine supplied in a wide range on the resulting organic phase ( 21 ) and the resulting aqueous phase ( 22 ) in a controlled manner quantitatively distributed and the different composition of the resulting polyamine fractions is adjusted and the resulting aqueous phase ( 22nd ) the extraction stage (C-4) and the resulting organic phase ( 21 ) at least partially ge processed according to o). 5. The method according to one or more of claims 1 to 4, characterized in that
the stream ( 20 ) in the extraction stage (C-3) instead of the low-polyamine streams ( 17 ) and / or ( 18 ) and / or ( 19 ) the polyamine-containing aqueous phase ( 04 ) resulting in the extraction stage (C-2) at least partially leads to. 6. The method according to one or more of claims 1 to 5, characterized in that
the resulting in the extraction stage (C-4) organic phase ( 07 ) at least partially in the extraction stage (C-3) of an aqueous phase containing water, a strong acid in the form of its ammonium salts, starting arylamine and optionally polyamine and formed from at least portions of the mass flow ( 17 ) and / or of the mass flows ( 18 ) and / or ( 19 ) and / or preferably from at least a part of the quantity of the aqueous phase ( 04 ) obtained in the extraction stage (C-2) is so dimensioned and adjusted in its composition that the polyamine fed to stage (C-3) is distributed in a wide range in a controlled manner to the resulting organic phase ( 21 ) and the resulting aqueous phase ( 22 ) and the different composition the resulting polyamine fractions are adjusted and the resulting aqueous phase ( 22 ) of the extraction stage (C- 4) and the resulting organic phase ( 21 ) at least partially further processed according to o). 7. The method according to claim 6, characterized in that one
in the at least two-stage, preferably multi-stage extraction stage (C-2) of the organic phase ( 17 ), first in the first stage from the point of view of the aqueous phase supplied, a low-polyamine partial stream of the aqueous phase, formed from at least a partial amount of the bulk stream ( 13 ) and / or the quantity streams ( 14 ) and / or ( 15 ) which may be present and, at the earliest in the second, optionally in the last stage, additionally counteracts the rest of the aqueous phase in the form of the polyamine-containing aqueous phase ( 21 ). 8. The method according to one or more of claims 1 to 7, because characterized in that the arylamine preferably used in the Condensation with formaldehyde starting arylamine used ver turns. 9. Use of the fractions generated according to claims 1 to 7 for the preparation of the corresponding aromatic polyisocyanate mix and for the production of polyurethane plastics. 10. Use of the fraction generated according to claims 1 to 7 NEN for the production of corresponding nuclear hydrogenated polyamines or as Crosslinker and epoxy hardener. 11. Use of the fraction generated according to claims 1 to 7 NEN for the production of the corresponding aromatic polyisocyanate mixtures and for the production of PU foams or as lacquer raw materials, especially the core-hydrogenated polyisocyanates.