Fractionation and purification of aromatic polyamine mixtures and the use thereof

The invention relates to a process for the fractionation and purification of aromatic polyamine mixtures and the use thereof.

BACKGROUND OF THE INVENTION 
The present invention relates to a process for the fractionation and 
purification of aromatic polyamine mixtures and the use thereof. 
The preparation of aromatic polyamines and polyamine mixtures, particularly 
of the diphenylmethane series, is described in numerous patent 
applications and patents, as is the use of said products. Outstanding 
importance is attached to the use of said products as raw materials for 
the preparation of isocyanates, usually by reaction of the polyamine 
mixtures with phosgene according to the generally conventional and well 
known methods. 
In many cases, however, the resulting isocyanates and isocyanate mixtures 
are not obtained in the form and composition subsequently used in 
preference in the isocyanate stage but have to be converted beforehand to 
the appropriate form for use by means of, in some case, time-consuming 
work-up and separation processes. Suitable polyamine preliminary stages 
which may be converted in a less time-consuming manner to the isocyanate 
use forms are in many cases difficult to produce or unobtainable in terms 
of process technology, or economically unattractive. 
An example is the production of 4,4'-diisocyanato-diphenylmethane which is 
important for the preparation of valuable polyurethane materials, the 
amine preliminary stage of which may be obtained usually from aniline and 
formaldehyde only together with isomers, particularly the 2,4'-isomers and 
polyamines with a relatively large number of functional groups. Although 
said constituents are the basis for the likewise sought after isocyanates, 
the separation of the crude isocyanates into the isocyanates and 
isocyanate mixtures suitable for subsequent use is not easy. Initially, a 
part of the binuclear compounds are usually separated from the remainder. 
The 4,4'-diisocyanato-diphenylmethane from the binuclear fraction is then 
separated from the other isomers in a second distillation stage requiring 
many separation stages. 
Even in recent times, the 2,4'-isomer in the enriched form has gained 
increasing importance as a polyurethane raw material, but may be enriched 
compared with the 4,4'-isomer and separated from the 2,2-isomer possibly 
present only by an elaborate distillation procedure. 
Isomer separation methods or enrichment methods within the fraction of 
polynuclear-homologues, or of polyfunctional amine constituents, and of 
isocyanates of the diphenylmethane series, are practically unknown. 
4,4'-Diaminodiphenylmethane is also attracting increasing interest as a raw 
material for di-(4-isocyanato-cyclohexyl)methane, the form of 
4,4'-diisocyanato-diphenylmethane hydrogenated on the nucleus, the 
provision of suitable aromatic polyamine mixtures for the hydrogenation 
stage with the highest possible content of 4,4'-diaminodiphenylmethane 
with simultaneously the smallest possible proportion of 
2,4'-diaminodiphenylmethane being very expensive. 
It is well-known that amines may be separated in certain cases by partial 
conversion to their salts, wherein the different base strengths inter alia 
may be used. These are usually monoamines with very different base 
strengths. Such disproportionation effects in two-phase systems have also 
been described already for aromatic polyamine mixtures, particularly of 
the diphenylmethane series (German Auslegeschriften 2,238,319 and 
2,528,697). 
As a result of the numerous components present in such a mixture, the amino 
groups of which hardly differ at all in terms of type practically all of 
them are arylamino groups--the effects are not particularly great and 
pronounced to be of interest for direct use with simple means. 
The object of the present invention was to provide a process which allows 
aromatic polyamine mixtures to be fractionated and purified in a simple 
manner so that isomers are obtained in a pure or enriched form.

DESCRIPTION OF THE INVENTION 
The above noted object is achieved by the process according to the 
invention which achieves a surprisingly good separating efficiency during 
the fractionation of aromatic polyamine mixtures, particularly of the 
diphenylmethane series, and in terms of its effect thereby far exceeds the 
known effects of the prior art. 
Other polyamine mixtures of varying composition are obtained during the 
fractionation of aromatic polyamine mixtures according to the invention. 
The derived polyamine mixtures may be those that are obtainable only at 
great expense by known synthesis routes. They may also be polyamine 
mixtures which are more suitable for a simplified preparation of 
isocyanates than the well known polyamine mixtures that are technically 
easy to prepare in that they, e.g., anticipate in the amine stage the 
isomer separations that are difficult to perform in the isocyanate stage. 
Such mixtures may also be completely new polyamine mixtures, because they 
cannot be prepared according to the prior art, which lead to completely 
new types of isocyanates. 
The process according to the invention may be used to obtain from any--thus 
including recycled--polyamine mixtures product fractions conforming with 
the standard or the starting polyamines despite the polyamine mixtures 
differing from the originally used polyamines or isocyanates in terms of 
contamination or non-random i.e. selective losses in the case of 
individual components. 
Finally, the process according to the invention may be used to 
co-fractionate synthesis-dependent by-products and intermediates unwanted 
in the end product and to deplete them in one product fraction and enrich 
them accordingly in another, and optionally to expel them in an individual 
fraction. 
The invention provides a process for the fractionation and purification of 
aromatic polyamine mixtures, particularly polyamine mixtures of the 
diphenylmethane series, which is characterized in that 
a) the polyamine staffing mixture (A) is distributed in a two-phase system 
comprising (i) a hydrophobic solvent phase (B) which is composed 
substantially of hydrophobic solvent and optionally an aromatic auxiliary 
amine that is practically insoluble in water and under normal pressure has 
a boiling point at least 20.degree. below the boiling point of the lowest 
boiling component of the staffing mixture and at least 20.degree. C. above 
the boiling point of the solvent, and optionally of polyamine, and (ii) an 
aqueous phase (C) comprising substantially water, a strong acid and 
auxiliary amine present at least partially in the salt form, and 
optionally polyamines present at least partially in the salt form, with 
the assistance of an extraction stage (4) operating on the counter-current 
principle with mixing of the phases, by introducing the starting polyamine 
mixture via the aqueous phase, into the extraction stage (4), and the 
organic phase (D) leaving the extraction stage (4) is separated 
b) optionally at least partially by means of an intermediate extraction 
stage (3) and/or 
c) optionally with separation of a partial stream before or after the 
extraction stage (3) optionally passed through, and return of the 
separated partial stream to the extraction stage (4) via an upstream 
extraction stage (2) 
d) in a multi-stage distillation (6.1), (6.2) into a first fraction (E), 
composed substantially of hydrophobic solvent and optionally auxiliary 
amine, a second fraction (F) composed substantially of auxiliary amine and 
optionally hydrophobic solvent and a distillation residue (G) composed 
substantially of a first polyamine fraction, and 
e) the aqueous phase (H) leaving the extraction stage (4) is fed to an 
extraction stage (5) in which an extraction of the aqueous phase takes 
place according to the principle of counter-current extraction with a 
solvent phase (J) comprising a solvent and auxiliary amine, and the 
aqueous phase (K) depleted in polyarylamine results, which is returned 
f) optionally at least partially via an intermediate distillation stage (8) 
g) optionally, at least partially via an intermediate extraction stage (3) 
and/or 
h) optionally at least partially, initially via an upstream extraction 
stage (2) and subsequently via an optionally present extraction stage (3) 
i) to the extraction stage (4) where it is used again as stream (C), 
optionally after the addition of water and/or auxiliary amine, and 
j) the organic phase (L) obtained in the extraction stage (5) is split into 
a distillate (M) comprising hydrophobic solvent and auxiliary amine and a 
distillation residue (N) comprising a second polyamine fraction, after 
which the distillate (M) is combined with at least a partial quantity of 
the distillate (F) obtained in the second distillation stage (6.2) of the 
organic phase (D) and is subsequently returned to the extraction stage (5) 
where it is used again. 
The numbers and capital letters noted-above and used in the description 
which follows refer to streams and elements in the drawings. 
In preference, the process is carried out in such a way that 
f) before being re-used, the aqueous phase (K) leaving the extraction stage 
(5) is freed at least partially from a part (X) of the water contained 
therein by distillation (8), said water being used optionally for washing 
(6.0) that part of the organic phase (D) leaving the extraction stage (4) 
and/or of the organic phase (P) leaving the extraction stage (3) fed to 
work-up by distillation (6.1), (6.2), and/or for washing (7.0) that part 
of the organic phase (L) leaving the extraction stage (5) fed to work-up 
by distillation (7.1) for the purpose of removing acid traces, the water 
(Y) obtained in so doing is returned to the aqueous phase at a suitable 
place and the resulting concentrated aqueous phase is combined with the 
optionally remaining residue of (K) and re-used as stream (C). 
The process according to the invention is carried out particularly 
preferably in such a way that 
b) the organic phase (D) obtained in the extraction stage (4) is extracted 
in counter-current at least partially in an intermediate extraction stage 
(3) with at least a partial quantity of stream (C) and/or is extracted in 
counter-current with at least a partial quantity of the aqueous phase 
obtained in the optionally present upstream extraction stage (2), the 
aqueous phase resulting in the intermediate extraction stage (3) is fed to 
the extraction stage (4) and the organic phase obtained in the 
intermediate extraction stage (3) is fed to the work-up stage (6). 
A further improved and therefore preferred embodiment of the process 
according to the invention consists in that 
c) a partial stream of the organic phase (D) leaving the extraction stage 
(4) and/or partial stream of the organic phase leaving the optionally 
present intermediate extraction stage (3) is separated, and extracted in 
counter-current in an upstream extraction stage (2) with a partial 
quantity, preferably with the entire quantity of the aqueous phase 
available as stream (C), the organic stream used in the extraction stage 
(2) is metered such that the most extensive transfer possible of the 
polyamine contained in the above-mentioned organic stream to the aqueous 
phase takes place in (2), the aqueous phase resulting in the upstream 
extraction stage (2) is fed to the extraction stage (3) optionally after 
the addition of water from stream (Y) and/or auxiliary amine, and the 
organic phase (T) obtained in the upstream extraction stage (2) and 
depleted in polyamine is fed to the extraction stage (4). 
More particularly, the present invention, in its broadest embodiment, is 
directed to a process for the fractionation and purification of aromatic 
polyamine mixtures, in particular of polyamine mixtures of the 
diphenylmethane series, comprising: 
a) mixing the polyamine starting mixture (A) in a first extraction stage 
(4) with a two-phase system comprising 
(i) a hydrophobic solvent phase (B) which consists essentially of 
hydrophobic solvent and optionally an aromatic auxiliary amine which is 
substantially insoluble in water and exhibits at normal pressure a boiling 
point which is at least 20.degree. C. below the boiling point of the 
lowest-boiling component of the starting mixture and at least 20.degree. 
C. above the boiling point of the solvent, and optionally polyamine, and 
(ii) an aqueous phase (C) consisting essentially of water, a strong acid 
and auxiliary amine present at least in part in the salt form, and 
optionally polyamines present at least in part in the salt form, 
with said first extraction stage (4) operating on the countercurrent 
principle, and wherein said polyamine starting mixture (A) is introduced 
into said first extraction stage with said aqueous phase (C), with a first 
aqueous phase (H) and a first organic phase (D) exiting said first 
extraction stage (4), 
b) distilling said first organic phase (D) in a multi-stage distillation 
(6.1), (6.2) into 
i) a first fraction (E) consisting essentially of hydrophobic solvent and 
optionally auxiliary amine, 
ii) a second fraction (F) consisting essentially of auxiliary amine and 
optionally hydrophobic solvent, and 
iii) a distillation residue (G) consisting essentially of a first polyamine 
fraction, 
c) extracting said first aqueous phase (H) in a second extraction stage (5) 
with a solvent phase (J) consisting essentially of hydrophobic solvent and 
auxiliary amine, said second extraction stage (5) operating on the 
countercurrent principle, with i) a second aqueous phase (K), said second 
aqueous phase (K) being reduced in amine content and ii) a second organic 
phase (L) exiting said second extraction stage (5), 
d) separating at least a portion of said second organic phase (L) in a 
distillation stage (7.1) into 
i) a first distillate (M) consisting essentially of hydrophobic solvent and 
auxiliary amine, and 
ii) a distillation residue (N) consisting essentially of a second polyamine 
fraction, 
e) recycling said second aqueous phase (K) as at least a portion of stream 
(C), and 
f) combining said first distillate (M) with a least a portion of said 
second fraction (F) to form at least a portion of solvent phase (J). 
The auxiliary amine used is preferablyaniline and the polyamine mixture of 
the diphenylmethane series used is preferably a polyamine mixture of the 
kind obtained during acid-catalyses aniline-formaldehyde condensation. 
The polyamine mixtures treated in this way, i.e. the fractions produced 
with the process according to the invention, are used for the preparation 
of the corresponding aromatic polyisocyanate mixtures and for the 
preparation of polyurethane plastics. Moreover, the fractions produced 
according to the process of the invention may be used for the preparation 
of the corresponding polyamines hydrogenated on the nucleus or as 
cross-linking agents and as epoxy curing agents. The corresponding 
polyisocyanates prepared from the fractionated polyamine mixtures are used 
preferably for the preparation of polyurethane foams. 
Starting mixtures are, for example, technical-grade arylamine mixtures, of 
the kind obtained during preparation from the starting compounds or of the 
kind obtained during recovery. Examples of starting arylamine mixtures for 
the fractionation and purification of which the process according to the 
invention is particularly suitable are 
1. Polyamine mixtures of the diphenylmethane series, of the kind produced 
during the condensation and acid-catalyses rearrangement of aniline with 
formaldehyde, 
2. Polyamine mixtures of the diphenylmethane series, of the kind obtained 
during acid-catalyses condensation of substituted anilines with 
formaldehyde, 
3. Polyamine mixtures of the diphenylmethane series, of the kind obtained 
during mixed condensation of substituted anilines with one another and/or 
aniline with formaldehyde, 
4. Polyamine mixtures of the diphenylmethane series, of the kind obtained 
during the condensation, including mixed condensation, of substituted 
anilines and/or aniline with aldehydes and/or ketones, 
5. Polyamine mixtures of the diphenylmethane series of the kind produced 
during the nitration and subsequent reduction of di- and/or 
polyarylmethanes and/or substituted di- and/or polyarylmethanes; the term 
polyarylmethanes here means in particular the benzyl homologues of 
diphenylmethane, 
6. Polyamine mixtures of the diphenylmethane series, of the kind produced 
during the condensation of monoarylmonoamines (e.g. aniline, substituted 
anilines) and/or monoaryldiamines (phenylene diamines, substituted 
phenylene diamines) with aldehydes, ketones, particularly formaldehyde, 
and acid-catalyses rearrangement, and 
7. Polyamine mixtures of the triphenylmethane series, of the kind produced, 
e.g. during the nitration and subsequent reduction of triphenylmethane, 
particularly alkyl-substituted triphenylmethanes and its polynuclear 
homologues, particularly benzyl homologues. 
The hydrophobio solvents used are inert solvents with a boiling point in 
the range from 30.degree. to 280.degree. C., preferably from 80.degree. to 
200.degree. C., such as, for example, chlorobenzene, dichlorobenzene, 
benzene, toluene, ethylbenzene, cumene, xylene, dichloroethane, chloroform 
and carbon tetrachloride. Xylenes i.e. technical-grade xylene mixtures, 
particularly oxylene, toluene, ethylbenzene, cumene and chlorobenzene, are 
used in preference. The preferred solvents are those having a good solvent 
power for the polyamine mixtures used. 
The acids used are water-soluble protonic acids with a pKA value below 2.5, 
preferably below 1.5. Examples thereof are hydrochloric acid, hydrobromic 
acid, sulfuric acid, trifluoroacetic acid, methanesulphonic acid or 
phosphoric acid. Hydrochloric acid and methanesulphonic acid are 
preferably used. The acids mentioned may also be used in mixture with acid 
or neutral salts of such acids, such as, e.g. the corresponding ammonium 
salts or the corresponding alkali salts. The acids mentioned are not used 
in the free form but are present in the circuit system according to the 
invention in the form of the corresponding ammonium salts of the bases 
situated in the aqueous circuit system. They are generally polyamine 
mixtures of the kind of the starting mixtures and/or the auxiliary amines 
used. 
Monoarylamines such as, e.g. aniline and/or aniline derivatives 
alkyl-substituted on the nucleus and/or on the nitrogen, are generally 
used as auxiliary amine. Primary anilines are used in preference; aniline 
is particularly preferred. 
The process according to the invention may be carried out both batchwise 
and continuously. A preferred embodiment is the continuous method of 
operation. The process is carried out in all stages under the natural 
pressure of the system and preferably in an inert gas atmosphere 
(nitrogen). 
The process according to the invention may be repeated with each of the 
resulting product fractions in order to increase the enrichment or 
corresponding depletion effect. 
The process according to the invention may be carried out with two (FIG. 
1), with three (FIG. 2 and FIG. 3) or with four (FIG. 4) extraction 
stages. 
The flow diagrams shown in FIGS. 1 through 4 serve to explain the process 
according to the invention in more detail. The references in the figures 
have the following meanings: 
(1) a tank for the starting arylamine mixture 
(2) an upstream extraction stage 
(3) a first extraction stage 
(4) an (intermediate) second extraction stage 
(5) a (final) third extraction stage 
(6) a work-up stage comprising 
(6.0) a wash stage 
(6.1) a first distillation stage of a multi-stage distillation 
(6.2) a final distillation stage of a multi-stage distillation 
(7) a further work-up stage comprising 
(7.0) a wash stage 
(7.1) a distillation stage 
(8) a water evaporator 
(9) a tank for process product 
(10) a tank for a further process product 
The reference symbols A-U, X and Y denote the streams to which reference is 
made below and in the examples. 
The upstream extraction stage (2) is designed preferably as a multi-stage 
extractor. In the simplest case, the optionally interposed extraction 
stage (3) is composed of a mixer-separator unit, but multi-stage 
extraction units are also used here in preference. In the simplest case, 
the extraction stage (4) is a single-stage mixer-separator unit, but 
multi-stage extraction units are used in preference. 
The final extraction stage (5) is generally designed as a multi-stage 
extractor. 
The work-up stages (6) and (7) serve to separate the polyamine fractions 
which are obtained as distillation residues and are isolated as process 
products (G) and (N) in the tanks (9) and (10), and for the recovery of 
the hydrophobic solvent used and of the auxiliary amine used as 
distillates. 
It has proved expedient to remove adhering traces of acid from the organic 
phases (D) and (D') and (L) and (L') fed to the distillation stages by 
extraction with water in upstream wash stages (6.0) and (7.0) before their 
treatment by distillation. 
The actual work-up stage (6) generally, comprises an at least two-stage 
multi-stage distillation of which the first stage (6.1) provides a 
hydrophobic solvent as distillate (E) from which polyamine has been 
removed and which is depleted in auxiliary amine in comparison with the 
inflow product (D) and (D') and/or (P) and (P'), and of which the final 
stage (6.2) provides a depleted auxiliary amine as distillate (F) in 
comparison with (D) and (D') and/or (P) and (P'). 
The complete separation of hydrophobic solvent and auxiliary amine by 
distillation is not necessary when carrying out the process according to 
the invention. 
In addition, the first polyamine fraction of the starting mixture (A) 
contained in stream (D) and (D') and/or (P) and (P') is obtained as 
distillation bottom product (G) in the final distillation stage (6.2). 
In the simplest case, the work-up stage (7) comprises a distillation column 
(7.1) which is designed such that an extensive separation of hydrophobic 
solvent and auxiliary amine jointly as distillate (M) from the polyamine 
fraction (N) contained in the inflow to (6) takes place by distillation. 
Preferably, however, the work-up stage (7) of the process according to the 
invention is also designed as a multi-stage distillation on account of the 
improved use of energy. 
The distillation stage (8) is a device with which water can be removed by 
distillation from the aqueous phase of the system or from a partial stream 
of the aqueous phase. Such a stage is not necessary in principle for 
carrying out the process according to the invention, but because of the 
resulting advantages the embodiments including a water distillation stage 
(8) are preferred. 
The aqueous phase containing the acid is practically a closed circuit 
system, so the stage (8) may, in principle, be inserted in any position of 
said circuit system. The position of stage (8) following the extraction 
stage (5) and before entry to the extraction stage (4) is the most 
advantageous and therefore the preferred embodiment. 
The quantity of water removed (X), optionally after being divided up into 
partial streams and the different use thereof, is returned to the system 
at a suitable location in the form of the stream (Y) as a whole or in 
partial streams, so that an extended and optionally branched inherently 
closed aqueous circuit system is produced. 
The system also includes the wash stages (6.0) and/or (7.0). The latter are 
extraction stages operating in one or more stages on the counter-current 
principle. In wash stage (6.0), the organic phase (D) and (D') and/or (P) 
and (P') is freed from adhering traces of acid with a partial stream of 
(X), and in wash stage (7.0) the organic phase (L) and (L') is freed from 
adhering traces of acid with the use of another water partial stream of 
(X). 
The distillate (X) contaminated with hydrophobic solvent and auxiliary 
amine is highly suitable for wash stages (6.0) and (7.0). The resulting 
wash waters generally have a very much lower acid concentration than the 
actual acid circuit, so these may be recycled without difficulty in the 
form of stream (Y) or its partial streams; optionally, a partial quantity 
of distillate of (X) may be fed from (8) past the wash stages after (Y) 
and used to control the varying water content of the aqueous phase in the 
individual extraction stages. 
The practically quantitative circuit operation of the acid used allows the 
use of expensive acids such as e.g. methanesulphonic acid which in turn, 
because of its reduced corrosion tendency, permits the use of inexpensive 
materials in the apparatus of the process according to the invention. 
It has proved advantageous to define the acid content of the aqueous phase, 
independently of the varying amine content occurring in the aqueous phase 
of a two-phase system, by means of a so-called "molarity". 
The "molarity" is defined as the theoretical concentration of 100% 
protonated amine (i.e. same number of acid and amine equivalents) in a 
volume of aqueous phase reduced mathematically by the proportion of 
unprotonated amine according to the formula: 
##EQU1## 
The molarity thus defined may assume values of up to 6 and is varied in a 
controlled manner in this range depending on the--product-related in this 
case--separation task on which the relevant embodiment is based. 
It may also be advantageous within an embodiment of the process according 
to the invention to operate the individual process stages through which 
the aqueous phase passes, particularly the extraction stages (2) to (5), 
with a different molarity in the aqueous phase by withdrawing or adding 
water from or to the aqueous phase between the individual stages. 
The upper limit of said operating range is technically limited on the one 
hand by the increasing crystallization tendency of the amine salts with 
increasing concentration, particularly at high degrees of protonation, and 
on the other hand by the increasing mutual solubility of the phases in one 
another, particularly at low degrees of protonation. The degree of 
protonation represents the ratio of acid equivalents to amine equivalents. 
The lower limit of said range is limited by economic factors by the 
decreasing acid content and hence the quantitative decrease in the 
separating efficiency, i.e. for an outstanding qualitative separating 
efficiency and without technical difficulties, an increasingly large 
volume of aqueous phase is required for the separation of a given quantity 
of amine as the molarity falls. 
According to one variant of the process of the invention, the feeding of 
the starting polyamine mixture (A) from the storage vessel (1) takes place 
by mixing with the partial stream (C) and introduction of the mixture into 
the extraction stage (4). 
The stream (C) is generally composed of water, a strong protonic acid, 
auxiliary amine and optionally polyamine. The acid is present in the form 
of its salts dissolved in water with auxiliary amine and optionally with 
polyamine. The amino groups of auxiliary amine and optionally polyamine 
are always present in (C) in a stoichiometric excess, based on the acid. 
The degree of protonation in (C) is generally 10-90%, for the aniline used 
preferably as auxiliary amine it is preferably 25-70%. 
The well-defined molarity of stream (C) measured and controlled in narrow 
limits for the relevant embodiment of the process according to the 
invention is varied in a controlled manner in a wide range depending on 
the--product-related in this case -separation task on which the relevant 
embodiment is based. Generally, the aqueous phase fed to the extraction 
stage (4) of the process according to the invention has a molarity of 
between 0.5 and 6. 
In extractor (4), stream (B) is passed in counter-current to the mixture 
produced from (A) and (C). 
The organic phase (B) is generally composed of auxiliary amine and/or 
polyamine, in addition to hydrophobic solvent, the latter polyamine 
preferably having the composition of the second process partial product 
(N). 
if an organic phase (B) without polyamine is used, a polyamine fraction is 
obtained in the aqueous phase (H) leaving the extraction stage (4), in 
which fraction the relative enrichment of the components contained in 
preference in said phase may be increased selectively and maximized at the 
expense of the polyamine concentration in the aqueous phase. 
The effect of polyamine as a constituent of the organic phase (B) is that 
the phase (H) leaving the process stage (4) has a polyamine concentration 
that is higher and hence more advantageous in energy terms for carrying 
out the process of the invention than when an organic phase (B) without 
polyamine is used. 
As a result of the preferred use of a polyamine with the composition of the 
second partial product (N) as constituent of the organic phase (B), the 
relative enrichment of the polyamine components contained in preference in 
the aqueous phase (H) leaving the separation stage (4) and hence of the 
second polyamine fraction (N) may be varied and maximized at a higher and 
hence more advantageous concentration level due to equilibrium adjustment 
with self-intensification of the separating effect. 
In the simplest case, stream (B) is formed from the hydrophobic solvent 
from which polyarylamine (G) has been removed and which is depleted in 
auxiliary amines, and which is obtained as distillate stream (E) in the 
distillation stage (6.1) and to which is added optionally a partial 
quantity of the distillate stream (F) of distillation stage (6.2) from 
which polyamine (G) has been removed and which is depleted in hydrophobic 
solvent. 
In a preferred embodiment, at least a partial quantity of the distillate 
stream (E) and optionally at least a corresponding additional partial 
quantity of the distillate stream (F) is added to the stream (J) used as 
extraction agent in the final extraction stage (5) and, after passing 
through stage (5), removed as a partial quantity from the resulting 
organic phase (L) and added to the stream (B). 
Optionally, in a particularly favorable but not generally applicable 
embodiment, the total quantity of streams (E) and (F) are added to the 
stream (J) and used initially as extraction agent in extraction stage (5) 
so that the stream (B) is formed exclusively from a partial quantity of 
the stream (L) leaving the extraction stage (5). 
The aromatic amine content of the organic phase (B) is usually 15-60%, 
depending on the separating task. 
In the extraction stage (4) operated preferably in multiple stages, the 
organic phase (B) and the mixture of starting polyamine mixture and 
aqueous phase (C) are fed in counter-current with intimate mixing. 
A partial transfer of polyamine to the organic phase usually takes place 
during this process, optionally in exchange for auxiliary amine in the 
opposite direction. 
The starting polyamine (A) introduced into the extractor (4) together with 
the aqueous phase (C) is divided into the aqueous phase (H) leaving the 
extractor and the organic phase (D) leaving the extractor (4) 
(quantitative fractionation). 
The quantitative division of the individual components of the starting 
polyamine mixture into the resulting aqueous phase (H) and the resulting 
organic phase (D) takes place under the conditions of the process of the 
invention with a surprisingly high selectivity such that the resulting 
product fractions have a different composition which, in certain 
circumstances, differs considerably from that of the starting polyamine 
mixture (qualitative fractionation). 
For example, starting from the aniline formaldehyde condensation products 
used in preference, it was found that the ortho-isomer form(s) of the 
polyamine component contained in two or more isomer forms in the starting 
mixture is (are) usually relatively enriched in the organic phase (D) 
leaving the separating stage (4); for example, 2,4'-diaminodiphenylmethane 
relative to 4,4'-diaminodiphenylmethane. Conversely, the resulting aqueous 
phase (H) is relatively depleted in the 2,4'-isomer, whilst the 
4,4'-isomer is relatively enriched. 
If several "ortho-isomers" are present in the starting polyamine, e.g. 
2,2'- and 2,4'-diamino-diphenylmethane, then the "ortho-richer" 
2,2'-isomer is more greatly enriched in the organic phase (D) compared 
with the "ortho-poorer" 2,4'-isomer, that latter itself being relatively 
enriched compared with the "even ortho-poorer" 4,4'-isomer. 
The enrichment and depletion effect found initially with the aniline 
formaldehyde condensation products of the diaminodiphenylmethane series 
was associated on a purely empirical-descriptive basis with the criterion 
of ortho and para substitution. The derived characterization of the 
process products as "ortho-rich" and "ortho-poor" is relative, and was 
expressed by the term "degree of ortho-substitution". 
The "degree of ortho-substitution" is defined as the ratio of ortho amino 
group to methylene group relationships to the total number of all the 
amino group relationships. This term can cover practically all the isomer 
separations for polyamines which are produced from arylamines, including 
substituted arylamines, with carbonyl compounds in an aqueous acid medium. 
Surprisingly, the same enrichment-depletion effect--classified according to 
degree of ortho-substitution--was also found for the well-characterized 
and analytically detectable isomeric trinuclear compounds from 
aniline-formaldehyde condensation. 
The same applies to the separation of condensation products from 
formaldehyde with aniline and diaminoaryl compounds such as phenylene or 
alkyl-substituted phenylene diamines. 
The polyamine mixtures mentioned hitherto, as a result of their 
preparation, possess amino groups which are practically only in the ortho 
and/or para position to methylene groups. 
Within one group of isomeric compounds, those with the higher degree of 
ortho substitution are usually enriched in the organic phase (D) during 
fractionation compared with the isomers with a lower degree of ortho 
substitution. 
Polyamine mixtures particularly of the diphenylmethane series including the 
relevant polynuclear homologues which are prepared according to other 
processes, for example, by nitration of diphenylmethane or 
methyldiphenylmethanes and subsequent reduction possess, in addition to 
amino groups in the ortho and para positions, other amino group-methylene 
group relationships as a result of the preparation. The process according 
to the invention is equally effective for said polyamine mixtures. 
For example, a polyamine mixture which primarily represents an isomer 
mixture of 
##STR1## 
can be prepared from a mixture of 2- and 4-methyldiphenylmethane by 
nitration and subsequent reduction. 
During the fractionation of such mixtures by means of the process of the 
invention, the 3,2'-isomers in the organic phase (D) are enriched compared 
with the 3,4'-isomers. 
The criterion "ortho-rich" and "ortho-poor" or the degree of 
ortho-substitution in said polyamine mixtures no longer covers all the 
isomers and should therefore be applied mutatis mutandis in that, instead 
of the terms "in the ortho position" and "in the para position", the 
isomers are classified into those with a smaller (=ortho) and those with a 
larger (=para) spatial distance of the amino groups--usually situated on 
different six-membered rings--to the methylene bridge or of the amino 
groups to one another. 
A further class of aromatic polyamine mixtures which can be fractionated 
very effectively by means of the process according to the invention are 
the polyamines of triphenylmethane and its polynuclear homologues, 
preferably benzyl homologues, of the kind produced, e.g. by nitration and 
subsequent reduction of the corresponding hydrocarbon mixtures. 
During the fractionation of technical-grade polyamine mixtures of the last 
classes of substance mentioned 
I. Mixed condensation products of mono- and diaminoaryl compounds with 
formaldehyde and general carbonyl compounds, 
II. Polyamine mixtures from processes by nitration and subsequent reduction 
of diphenylmethane and preferably substituted, particularly 
alkyl-substituted, diphenylmethanes and the relevant homologues, and 
III. Polyamine mixtures from processes by nitration and subsequent 
reduction of triphenylmethane and preferably substituted, particularly 
alkyl-substituted, triphenylmethanes and the relevant polynuclear benzyl 
homologues 
a further surprising selectivity was found in addition to the pure isomer 
separation. 
Polyamine mixtures of the substance classes I to III mentioned contain or 
may contain components in which at least one aryl nucleus per molecule 
beam more than one and usually two amino groups. Said components may be 
the preferred components of the polyamine mixture without having to be the 
main products in quantitative terms, due to the process. 
In order to improve the characterization of such components, the term 
"degree of amino substitution" is used with which primarily the number of 
amino groups of one component in relation to the number of aryl nuclei is 
characterized. For aniline and its condensation products with 
formaldehyde, this expression is always 1.0, for phenylene diamine and its 
condensation products always 2.0. For pure mixed condensates, the value of 
1.5 is obtained for the diphenylmethane isomers and values of between &gt;1.0 
and &lt;2.0 are obtained for the polynuclear homologues. If the term degree 
of amino substitution is used statistically to characterize 
technical-grade polyamine mixtures, values of between 1.0 and 2.0 are 
likewise obtained. 
When fractionating polyamine mixtures with a degree of amino substitution 
of &gt;1.0 it was found that the components with a higher degree of amino 
substitution are relatively enriched in the aqueous phase resulting in the 
actual separation stage, the enrichment being greater with increasing 
degree of amino substitution. 
The process according to the invention thus also opens up the possibility 
for this class of substances of divorcing the production form of the raw 
materials (amine stage) and the use form of the end products (isocyanate 
stage) so that a separate optimization of both stages is facilitated to 
the extent of obtaining completely new isocyanate mixtures. 
These "achievements" are supplemented by a further criterion of selectivity 
which was found during the fractionation of technical-grade polyamine 
mixtures, particularly those with polynuclear homologues, and relates to 
the "nuclearity" of the polyamine mixtures. 
The term "nuclearity" primarily expresses the number of aryl units of a 
component of an aromatic polyamine mixture. In the wider sense, the term 
nuclearity is used to express statistically a nuclearity of the total 
mixture for a polyamine mixture composed of numerous components with an 
individual, exact nuclearity. 
Particularly surprisingly, it was found when fractionating polyamine 
mixtures with polynuclear components, particularly when fractionating 
technical-grade mixtures of aniline-formaldehyde condensates, that the 
polynuclear components in the organic phase leaving the fractionation 
stage can be both relatively enriched and relatively depleted in a 
controlled manner, depending on the molarity of the aqueous phase in the 
extraction stage (4). 
A high molarity of the aqueous phase in (4) within the given molarity range 
leads to a relative depletion of polynuclear components in the organic 
phase (D) and consequently to a relative enrichment in the aqueous phase 
(H). A low molarity of the aqueous phase in (4) within the given molarity 
range leads to a relative enrichment of polynuclear components in the 
organic phase (D). 
The surprising finding may be extended and refined to the extent that the 
relative enrichment and depletion also takes place amongst the polynuclear 
homologues themselves. In a technical-grade mixture of 
diaminodiphenylmethane, for example, if the trinuclear components in one 
fraction are relatively enriched or depleted compared with the binuclear 
components, a relative enrichment or depletion of tetranuclear components 
compared with trinuclear components is also found, i.e. an even greater 
relative enrichment or depletion, and the same occurs with pentanuclear 
components compared with tetranuclear components etc. 
As a result of this and the isomer separation taking place simultaneously 
and always in the direction of a relative increase in the "degree of 
ortho-substitution" in the organic phase (D), and as a result of the 
possibility of repeating the separation according to the invention with 
individual product fractions, optionally with modified process parameters, 
there are numerous possibilities starting from well known and readily 
obtainable polyamine mixtures, of obtaining by means of the process of the 
invention less readily obtainable or completely new, because hitherto 
unobtainable by the prior art, polyamines and hence polyisocyanates. This 
is particularly true of products of the diamino- and 
diisocyanatodiphenylmethane series and quite particularly for polyamine 
and polyisocyanate mixtures with an extremely high proportion of 
polynuclear components. 
The enrichment and depletion usually becomes more effective with increasing 
degree of protonation in the aqueous phase of the separation stage. 
Moreover, the process according to the invention also proves to be 
generally effective for other polyamines with a similar structure. For 
example, the polyamine mixtures already mentioned which are obtained by 
nitration of di- and polyarylmethanes and subsequent reduction may also 
contain monoaminopolyaryl methane compounds or components in which one or 
more methylene groups have been converted by side-reactions into keto- 
and/or hydroxymethylene groups and thus into unwanted byproducts. 
Numerous incompletely rearranged intermediate compounds and by-products may 
occur during the condensation of arylamines with carbonyl compounds. Most 
of these compounds usually undergo enrichment in one of the resulting 
fractions during the fractionation of the polyamine mixtures containing 
them, so that the effect can be used for separation and fractionation. 
Such products may be optionally enriched in this way or may themselves be 
fractionated as selectively produced polyamine mixtures, such as, for 
example, polyaminobenzophenones or aminobenzylarylamine mixtures. 
The organic phase (D) leaving the extraction stage (4) contains, inter 
alia, small quantities of acid, generally and depending on the process 
parameters in the extraction stage (4) between 0.01 and 0.5 wt. %, which 
are removed advantageously prior to work-up of the stream (D) by 
distillation. 
In the simplest case, this takes place by neutralization with excess dilute 
aqueous bases, for example, dilute sodium hydroxide solution. The washing 
out of the acid or its amine salts from the organic phase with water is, 
however, preferred so that optionally only residual traces are removed by 
contact with dilute sodium hydroxide solution or by means of an ion 
exchanger. 
The wash water used is removed from the aqueous acid circuit by means of a 
water evaporator and added thereto at a suitable location in process terms 
after passing through the wash stage(s) together with the acid. 
The organic phase (D) is transferred to the at least two-stage distillation 
stage (6.1), (6.2), optionally after passing through the acid wash stage 
(6.0). 
In the first distillation stage (6.1), a distillate (E) is separated which 
contains the majority, preferably almost the entire quantity of the 
hydrophobic solvent contained in (D) in addition to a part of the 
auxiliary amine contained in (D). Generally, the distillate (E) contains 
&lt;50% of auxiliary amine, preferably 15-30%. 
In the final distillation stage (6.2), the remaining auxiliary amine, 
optionally in addition to the residual quantity of hydrophobic solvent, is 
separated as distillate (F) from the first partial product (G) obtained as 
distillation bottom product and collected in the process product tank (9). 
Generally, (F) contains &lt;50% of hydrophobic solvent, preferably 15-30%. 
The corresponding second process partial product is situated in the aqueous 
phase (H) leaving the extraction stage (4). In a multi-stage extraction 
stage (5) operated preferably at 80.degree.-110.degree. C., the second 
partial product is extracted in exchange for auxiliary amine from the 
aqueous phase (H), optionally after the addition of water to reduce the 
molarity and optionally after the addition of auxiliary amine to reduce 
the degree of protonation, and in so doing is transferred to the organic 
phase (L). 
The molarity of the aqueous phase used in (5) is preferably &lt;2.5, while the 
degree of protonation of the aqueous phase used in (5) is preferably &lt;60%. 
The extraction agent (J) used is a mixture of hydrophobic solvent and 
auxiliary amine, which is composed substantially of the distillate 
fraction (M) of the distillation stage (7.1) and at least a partial 
quantity of the distillate fraction (F) of the distillation stage (6.2), 
and is optionally supplemented by at least a partial quantity of the 
distillate stream (E). 
The weight ratio of auxiliary amine to solvent in (J) is generally between 
0.5:1 and 3:1, preferably between 1:1 and 2:1. 
The weight ratio of extraction agent (J) to aqueous phase is generally 
between 0.3:1 and 3:1, preferably between 0.7:1 and 2:1. 
The organic phase (L) resulting in (5) or the partial quantity thereof is 
fed to the distillation stage (7.1), optionally after passing through the 
wash stage (7.0) and/or optionally after removal of acid traces with 
dilute sodium hydroxide solution. 
The separation by distillation of the distillation residue (N) takes place 
in distillation stage (7.1), which residue is collected as a second 
partial product in the process product tank (10). 
Distillation stage (7.1) may comprise, for example, a single-stage 
evaporator which provides a distillate (M) in addition to the distillation 
residue (N). 
The distillate (M) contains, in addition to auxiliary amine, the entire 
hydrophobic solvent from (L) or the partial quantity thereof, and is used 
as extraction agent (J) after addition of at least a partial quantity of 
(F). For the general case that (F) contains hydrophobic solvent in 
addition to auxiliary amine, a corresponding equalization of hydrophobic 
solvent with respect to (E) is carried out if necessary, i.e. to the 
organic circuit in order to obtain the first partial product. 
The aqueous phase (K) resulting in (5) is returned to the extraction stage 
(4), preferably at least partially via a distillation stage (8), in which 
the water quantity (X) is removed from the aqueous phase. 
The route via (8) is absolutely vital if the extraction stage (4) is 
operated with a higher molarity of the aqueous phase than the extraction 
stage (5). In this case, the at least proportional return feed of water 
(Y) to the aqueous acid circuit takes place after leaving the stage (4) 
and before entering the stage (5). 
In principle, the aqueous phase (H) resulting in the process stage (4) may 
be fed directly to the extraction stage (5). As, however, the upper 
molarity range of the extraction stage (4) much preferred for certain 
separation tasks lies above the preferred molarity range of the extraction 
stage (5), a preferred embodiment of the process of the invention is to 
divorce the molarities from those in the various extraction stages by 
removing water by distillation from the inherently closed system of the 
aqueous phase, optionally at a suitable location, and adding it again at 
another suitable location. 
With the aid of a water distillation stage (8), water is removed from the 
aqueous phase containing the acid, or from a partial stream of the aqueous 
phase, preferably after leaving the extraction stage (5) and before re-use 
at the beginning of the process, said water being added again as a whole 
(Y) or in partial quantities at one or more locations before the aqueous 
phase enters the extraction stage (5). 
A second variant of the process according to the invention is more 
advantageous and preferred as an embodiment, in which, additionally in the 
first polyamine fraction (G), the relevant enrichment of the components 
contained preferably in said fraction can be increased substantially and 
varied in a controlled manner, by extracting the organic phase (D) 
obtained in the extraction stage (4) at least partially in an intermediate 
extraction stage (3) from the viewpoint of phase (D) with an aqueous phase 
which comprises in the present case of variant 2 substantially at least a 
partial quantity of the stream (C). 
For formal reasons, the organic phase fed to the extraction stage (3) is 
called stream (O), even if, as explained by way of example in the present 
case, it corresponds optionally at least in terms of composition but also 
preferably in terms of quantity with stream (D). 
Even during the single-stage execution of the extraction stage (3), for 
example as a mixer-separator unit, a pronounced further relative 
enrichment of the components already enriched in (D) compared with 
starting polyamine (A) takes place in the resulting organic phase (P) 
depending on the type and, in particular, the quantity of aqueous phase 
used, associated with a decrease in the polyamine content in the organic 
phase (P). In view of the better effectiveness, however, the intermediate 
extraction stage (3) is preferably designed as a multi-stage extractor 
operated in counter-current. 
The aqueous phase (Q) obtained in the extraction stage (3) contains the 
other corresponding fraction of the polyamine introduced with stream (O) 
in which fraction the components enriched in (P) are depleted accordingly. 
The extent of the relative depletion, i.e. the composition of the 
polyamine contained in (Q) is controlled under the relevant process 
conditions of the multi-stage extraction stage (3) by the qualitative and 
quantitative distribution equilibrium between the organic phase (O) fed in 
and the aqueous phase (Q) discharged. 
The molarity of the aqueous phase in the extraction stage (3) is higher or 
the same or lower, depending on the separation task, based on the molarity 
in the downstream extraction stage (4) from the viewpoint of the aqueous 
phase, and is controlled by the addition or removal of water at a suitable 
location. 
The aqueous phase (Q) resulting in process stage (3) is fed together with 
the optionally present remainder of (C) to the extraction stage (4), 
optionally after the addition of water. 
The organic phase (P) resulting in stage (3) is fed together with the 
optionally present remainder of (D) to the work-up stage (6) in order to 
obtain the polyamine fraction (G). 
With the second variant of the process according to the invention, the 
relative enrichment in both resulting polyamine fractions can be varied in 
a controlled manner and maximized. In addition to this great versatility 
and efficiency in terms of quality, the second process variant also offers 
a favorable embodiment from an energy viewpoint, at least for the second 
polyamine fraction (N). 
The expenditure of energy associated with obtaining the first polyamine 
fraction (G) on the other hand increases more sharply in relative terms 
the lower the quantitative proportion of (G), based on the polyamine 
mixture (A) used, because the remaining polyamine content (G) in the 
organic phase (D) and (P) to be worked up by distillation optionally 
becomes increasingly small. 
The effect is brought to bear in particular when the components separated 
with (G) are contained in the starting mixture (A) only in a small 
concentration and/or are enriched to a relatively high degree in the 
fraction (G), e.g. during the separation according to the invention of 
polyamine mixtures of the diphenylmethane series. 
An improved embodiment in this respect is the third variant of the process 
according to the invention. Starting from the first variant, this is 
extended to the extent that the organic phase (D) leaving the process 
stage (4) is divided into a partial stream which is fed to work-up stage 
(6) with the further aim of obtaining the polyamine fraction (G), and a 
second partial stream which is fed to an upstream extraction stage (2). 
For formal reasons, the organic phase fed to the upstream extraction stage 
(2) is called stream (R), even if, as explained by way of example in the 
present case, it corresponds optionally in terms of composition with 
stream (D). 
Extraction stage (2) is usually a multi-stage extractor operated in 
counter-current in which the organic phase (R) fed in is extracted with at 
least a partial quantity, preferably with the total quantity of the 
aqueous phase (C) available for re-use. 
The stream (R) fed to extractor (2) is metered such that, during the 
reaction with stream (C), the most extensive possible and preferably 
practically quantitative transfer of the polyamines contained in the 
organic phase (R) to the aqueous phase (S) leaving the extractor (2) takes 
place. 
A higher molarity in the aqueous phase used in stage (2) resulting from 
process stage (8) of the process of the invention promotes and facilitates 
the transfer of polyamines from the organic phase (R) to the aqueous 
phase. 
The residual polyamine content in the organic phase (T) resulting in the 
process stage (2) is generally &lt;5 wt. %, preferably &lt;1 wt. %. Moreover, 
the permissible maximum amine content in (T) and particularly the 
polyamine content depends on the qualitative requirements in respect of 
the process products resulting from the relevant separation task, and in 
the case of variant 3 particularly in respect of the process partial 
product (N). Maintaining the relevant polyamine content for the quality of 
(N) is controlled within the scope of the industrial conditions by 
metering the partial stream (R) whilst exhausting the aqueous phase 
available. 
It is useful to the process and particularly to the extraction stage (2) 
that the greater the proportion of the second polyamine fraction (N) and 
consequently the smaller the proportion of the first polyamine fraction 
(G), the greater the aqueous phase (stream C) available for use in stage 
(2). A small polyamine fraction (G) usually means a low polyamine 
concentration in the organic phase (D) and a large expenditure of energy 
during work-up of such a phase. As a result of variant 3 according to the 
invention, the expenditure of energy in particular during isolation of the 
first polyamine fraction (G) can be reduced compared with variant 1. 
The contribution of process stage (2) within the scope of variant 3 towards 
improving the process according to the invention lies in the fact that, 
instead of the total stream with a relatively low and hence unfavorable 
polyamine concentration in energy terms, only a partial stream with a 
correspondingly increased and hence more favorable concentration in energy 
terms is obtained for the work-up by distillation (6) to obtain the first 
polyamine fraction (G), (quantitative enrichment), whilst an organic phase 
(T) which can be used as extraction agent at a suitable location is 
obtained from the other partial stream without distillation. 
The organic phase (T) largely free from polyamine leaving process stage (2) 
is fed to the extraction stage (4). 
In the preferably multi-stage extraction stage (4), the organic phase (T) 
is added as extraction agent, usually by mixing with stream (B) and 
addition to the first stage of the extractor from the viewpoint of the 
organic phase (B). 
Depending on an optionally present residual polyamine content in (T) and 
taking account of the quality of the second polyamine fraction (N), the 
organic phase (T) is added optionally to a later stage, from the viewpoint 
of the organic phase (B), optionally to the final stage of the multi-stage 
extraction stage (4). 
The aqueous phase (S) leaving the process stage (2) contains, in addition 
to the acid present in the form of its ammonium salt, auxiliary amine and 
polyamine, the latter with a composition that largely corresponds to the 
polyamine in the organic phase (R) fed in. 
In the case of variant 3 of the process according to the invention, the 
stream (S) is fed directly to the process stage (4), optionally after the 
addition of water from stream (Y) and/or further aqueous phase from stream 
(C). 
As the polyamine fraction contained in the aqueous phase (S) usually has a 
higher relative (qualitative) enrichment in the direction of the first 
polyamine fraction (G) based on the starting polyamine (A), the result for 
the aqueous phase fed to extraction stage (4) after the addition of 
starting polyamine (A) is an "enriched" mixed polyamine compared with said 
starting polyamine, depending on the quantity ratio. As a result of the 
distribution equilibrium between the aqueous phase fed in and resulting 
organic phase (D), a limited qualitative enrichment effect for the first 
polyamine fraction (G) is also obtained for variant 3. 
In a further variant 4 of the process according to the invention, the 
industrial measures of the preceding variants are brought together and 
combined. 
In the simplest case, the extraction stages (2) and (3) are added and each 
is carried out in the manner described with a partial stream of (C) and a 
partial stream of (D), which in this .case is divided into three partial 
streams. 
It is more advantageous to use as organic phase (R) in extraction stage (2) 
a partial stream of the stream (P) containing a polyamine fraction which 
is more highly enriched in qualitative terms and less concentrated in 
quantitative terms. 
In preference, variant 4 is carried out in such a way that a partial stream 
of (D) and/or preferably a partial stream of (P) is used as organic phase 
(R) in the extraction stage (2), and the aqueous phase (S) resulting in 
stage (2) is fed at least partially, preferably wholly to the extraction 
stage (3) and is used in (3) optionally with the addition of further 
aqueous phase from stream (C) and optionally auxiliary amine. In so doing, 
the organic phase (O) with its content of polyamine enriched in the same 
way is passed in counter-current to it in several stages with intimate 
mixing; optionally, the organic phase (O) is increased by the addition to 
(O) of a partial stream of the organic phase (T) resulting in the 
extraction stage (2). 
As a result of said measures, a further increase in the qualitative 
enrichment effect is brought about in the organic phase (P) resulting in 
(3). In quantitative terms, said result may be achieved by metering and 
dividing up the streams with a relatively high, and hence favorable in 
energy terms, polyamine content in the phases resulting in (3), 
particularly in the organic phase (P). 
The fact of combining the enrichment effect in (P) via the stream (R) as a 
partial stream of (P) and via the aqueous phase (S) has a 
self-intensifying effect. 
As a result of the embodiment according to the invention and the inclusion 
of the extraction stages (2) to (4) in variant (4) with process criteria 
such as disproportionation instead of fractional extraction in stage (3), 
with self-intensification due to connection with extraction stage (2) and 
recovery of extraction agent in stage (2) without distillation for use in 
process stage (4) and optionally in (3), there results a maximum 
qualitative separating efficiency which, in combination with the variation 
in molarity of the aqueous phases in stages (2) to (4), leads to a wide 
field of application of the process according to the invention. 
The invention is further illustrated but is not intended to be limited by 
the following examples in which all parts and percentages are by weight 
unless otherwise specified. 
EXAMPLE 
Starting polyamine mixture (A) (4,900 kg/h) is mixed with the stream (C) 
(19.307 kg/h) composed substantially of polyamine mixture, aniline, 
hydrogen chloride and water. Stream (C) is formed from streams (U) and 
(Q). 
The resulting aqueous phase (streams A+C) has the following average 
composition 
______________________________________ 
Stream (A) + (C) 28.6% polyarylamine 
(24.207 kg/h) 18.9% aniline 
5.8% hydrogen chloride 
46.7% water 
______________________________________ 
and is passed in counter-current to stream (B) in a multi-stage extractor 
(4) at 90.degree. C., which stream (B) has the following composition: 
______________________________________ 
Stream (B) 29.7% aniline 
(9.429 kg/h) 69.2% xylene 
approx. 1.1% water. 
______________________________________ 
The organic phase (D) leaving the extractor (4) is fed wholly to the 
extractor (3) and is in this case identical in terms of quantity and 
composition to stream (O). Stream (D) and (O) has the following average 
composition: 
______________________________________ 
Stream (D) and (O) 
22.8% polyarylamine 
(12.106 kg/h) 22.3% aniline 
53.9% xylene 
&lt;0.1% hydrogen chloride 
approx. 1.0% water. 
______________________________________ 
The aqueous phase (H) leaving the extractor (4) has the following average 
composition: 
______________________________________ 
Stream (H) 19.4% polyarylamine 
(21.530 kg/h) 21.7% aniline 
6.5% hydrogen chloride 
52.4% water. 
______________________________________ 
Stream (H) is combined with stream (Y) (approx. 2.9 kg/h) and passed in 
counter-current to the organic stream (J) in the multi-stage extractor (5) 
at 90.degree. C. 
______________________________________ 
Stream (H) + (Y) 54.9% aniline 
(24.441 kg/h) 44.1 % xylene 
Stream (J) approx. 1.0% water 
(21.958 kg/h) 
______________________________________ 
Stream (J) is formed from distillate stream (M) of the distillation stage 
(7.1) and a partial stream of (F). 
The organic phase (L) leaving the extractor (5) is obtained with the 
following average composition: 
______________________________________ 
Stream (L) 16.0% polyarylamine 
(25.000 kg/h) 44.1% aniline 
38.8% xylene 
&lt;0.1% hydrogen chloride 
approx. 1.0% water. 
______________________________________ 
Stream (L) is washed in counter-current with water (approx. 2 kg/h) in a 
washing stage (7.0) designed as a multi-stage extractor. 
For safety, the washed stream (L) is washed with dilute sodium hydroxide 
solution. The aqueous phase is removed as waste water. 
In the subsequent distillation stage (7.1), water, xylene and aniline are 
separated from the polyamine fraction (stream N) obtained as distillation 
bottom product. 
The distillate obtained in distillation stage (7.1)--optionally after 
mechanical separation of the water separated when cooling the 
distillate--is combined as stream (M) with a partial stream of the stream 
(F) comprising substantially aniline from distillation stage (6.2) to form 
the stream (J) used as extraction agent in extraction stage (5). 
The polyamine fraction (N) is collected in tank (10) as ortho-poor partial 
product in a quantity of approx. 4.0 kg/h. 
The aqueous phase (K) leaving extractor (5) has the following average 
composition: 
______________________________________ 
Stream (K) 0.8% polyarylamine 
(21.399 kg/h) 26.6% aniline 
6.6% hydrogen chloride 
66.0% water. 
______________________________________ 
Stream (K) is divided into a first partial stream which is concentrated in 
a water evaporator (8) by distillation of water (stream X: approx. 2.9 
kg/h) and then fed as stream (U) to extraction stage (4), 
______________________________________ 
Stream (U) 1.0% polyarylamine 
(11.375 kg/h) 33.3% aniline 
8.2% hydrogen chloride 
57.5% water 
______________________________________ 
and a second partial stream which is fed directly, i.e. with the 
composition of stream (K), to extraction stage (3). 
In the multi-stage extractor (3), the aqueous partial stream of (K) is 
passed in counter-current at 90.degree. C. to an organic phase (O), in the 
present case identical to stream (D) in terms of quantity and composition. 
The aqueous phase (Q) resulting in extractor (3) is combined with the 
aqueous phase (U) to form aqueous phase (C). 
______________________________________ 
Stream (Q) 24.1% polyarylamine 
(7.932 kg/h) 10.0% aniline 
5.9% hydrogen chloride 
60.0% water. 
______________________________________ 
The organic phase (P) resulting in the extractor (3) has the following 
average composition: 
______________________________________ 
Stream (P) 7.9% polyarylamine 
(11.374 kg/h) 33.6% aniline 
57.4% xylene 
&lt;0.1% hydrogen chloride 
approx. 1.0% water. 
______________________________________ 
In a washing stage (6.0) designed as a multi-stage extractor, the stream 
(P) is washed in counter-current with water from stream (X) (approx. 0.9 
kg/h). 
For safety, the washed stream (P) is washed with dilute sodium hydroxide 
solution. The aqueous phase is removed as waste water. 
The washed stream (P) from which acid residues have been removed is freed 
in a first distillation stage (6.1) from the major part of the xylene and 
a part of the aniline. The distillate (stream (E)) is used to form stream 
(B). 
In a second distillation stage (6.2), the aniline and residual xylene is 
distilled off from the bottom phase of (6.1). The distillate is divided 
into streams (B) and (J). 
There remains as distillation bottom product from stage (6.2) a polyamine 
mixture which is collected as stream (G) at a rate of 0.90 kg/h in tank 
(9). 
The acid quantities removed from the system via the safety neutralization 
stages during the wash with sodium hydroxide solution are replaced from 
outside by the addition of stream (C), and water quantities withdrawn are 
replaced by addition to stream (X). 
______________________________________ 
Polyarylamine GC: 
A (wt. %) G wt. %) N (wt. %) 
______________________________________ 
2,2'-diaminodiphenylmethane 
0.22 1.20 -- 
2,4'-diaminodiphenylmethane 
7.12 35.20 0.80 
4,4'-diaminodiphenylmethane 
60.20 26.40 67.80 
N-methyl-4,4'- 0.21 0.70 0.10 
diaminodiphenylmethane 
.SIGMA. diaminodiphenylmethane 
67.74 63.50 68.70 
.SIGMA. polynuclear polyamines 
32.26 36.50 31.30 
Quantity distribution 
100% 18.4% 81.6% 
______________________________________ 
Although the invention has been described in detail in the foregoing for 
the purpose of illustration, it is to be understood that such detail is 
solely for that purpose and that variations can be made therein by those 
skilled in the art without departing from the spirit and scope of the 
invention except as it may be limited by the claims.