9  5,648,519  10  In  this connection "degree of ortho-substitution" is  defined as the proportion of ortho amino group-methylene  The enrichment and depletion effect first found in the  compounds of the diaminodiphenylmethane series obtained  as products of aniline/formaldehyde condensation was asso› ciated purely empirically and descriptively with the measure  of ortho- and para-substitution. The characterization,  derived therefrom, of products of a process as "ortho-rich"  or "ortho-poor" is relative and was expressed by the term  "degree of ortho-substitution".  If several "ortho-isomers" are present in the starting  polyamine, for example,  2;2’- and 2,4’-diaminodiphenyl› methane, then the "ortho-richer" 2,2’-isomer is more highly  enriched in the organic phase (D) as compared with the  "ortho-poorer" 2,4’-isomer, which latter is for its part rela› tively enriched as compared with the "even ortho-poorer"  4,4’-isomer.  In  general the stream (C) consists of water, a strong  protonic acid, auxiliary amine and optionally polyamine.  The acid is present in the form of its water-soluble salt  together with auxiliary amine and optionally polyamine. The  sum of the amine groups of the auxiliary amine and option- In  the extractor  (3),  the stream (B) charged with (A) is  passed through counter to the aqueous phase (C).  The content of starting polyamine in stream (B) after  addition of  (A)  is generally from 5 to 60 wt. %, preferably  from 10 to 40  wt.  %.  In  general the content of arylamine, consisting of starting  polyamine and auxiliary amine, present in stream (B) after  addition of (A) is from 10 to 80 wt.%, preferably from 15  to 60 wt.%.  In  one variant of the process according to the invention,  the feed of the starting polyamine mixture (A) from the  storage tank  (1)  takes place by mixing with the flow (B),  formed from the stream (E) from the first distillation stage  (7.1),  consisting of hydrophobic solvent and optionally  auxiliary amine, and optionally a partial stream from  (S).  For example, starting from the preferably used products  of aniline formaldehyde condensation, it was found that  from a polyamine component present in two or more iso› meric forms in the starting mixture, as a rule the ortho- isomeric form(s) is (are) relatively enriched in the organic  phase (D) leaving the separator stage  (3);  for example,  2,4’-diaminodiphenylmethane relative to 4,4’› diaminodiphenylmethane. Conversely, the resulting aqueous  phase  (H)  is relatively depleted of the 2,4’-isomer, whereas  the 4,4’-isomer is relatively enriched.  The quantitative distribution of the individual compo› nents of the starting polyamine mixture between the result- ing aqueous phase  (H)  and the resulting organic phase (D)  takes place with a surprisingly high selectivity under the  conditions of the process according to the invention, so that  the resulting product fractions are of another composition,  greatly differing from that of the starting polyamine mixture  ( qualitative fractionation).  This range is restricted towards the lower end for eco› nomic reasons, owing to the decreasing acid content and  therewith the quantitative decline in separation efficiency,  that is, for an excellent qualitative separation efficiency  which is free from technical problems, with decreasing  molarity an increasingly large volume of aqueous phase is  necessary for the separation of a given quantity of amine.  The degree of protonation expresses the ratio of acid  equivalents to amine equivalents.  This operating range is in practice restricted towards the  upper end on the one hand by the increasing tendency of the  amine salts to crystallize with increasing concentration, in  particular at high degrees of protonation, and on the other  hand by the increasing mutual solubility of the phases with  one another, in particular at low degrees of protonation.  The starting polyamine (A) introduced together with the  organic phase  (B) into the extractor  (3)  is distributed  between the aqueous phase  (H)  leaving the extractor and the  organic phase (D) leaving the extractor  (3)  (quantitative  fractionation).  Within an embodiment of the process according to the  invention it may also optionally be advantageous to operate  the individual processing stages through which the aqueous  phase is passed. in particular the extraction stages  (2)  to  (6),  with a varying molarity in the aqueous phase, by withdraw› ing or adding water to the aqueous phase between the  individual stages.  The molarity defined in this way can assume values of up  to 6 and is purposively varied within this range according to  the-here product-related-problem of separation underly› ing the respective embodiment.  In  the aqueous phase  (H)  leaving the extraction stage  (3)  the acid is present as an aqueous solution of its ammonium  salts together with polyamine and optionally auxiliary  amine, which solution as a rule contains dissolved free  polyamine, that is, not bound in the form of a salt, and  optionally free auxiliary amine, that is, not bound in the form  of a salt.  During this process a transition of polyarylamine from the  organic phase (B) into the aqueous phase takes place as a  rule, optionally in exchange for auxiliary amine in the  opposite direction.  In  general the aqueous phase (C) passed to the extraction  stage  (3)  of the process according to the invention has a  molarity of between 0.5 and 4.5. Within the extraction stage  (3),  which is preferably operated in multiple stages, the  stream (B) charged with (A) and the aqueous phase (C) are  passed counter to one another with intimate mixing.  The molarity of the stream  (C), which is clearly defined  and is measured and controlled within narrow limits for the  respective embodiment of the process according to the  invention, is purposively varied within a wide range accord- ing to the-here product-related-problem of separation  underlying the respective embodiment.  The degree of protonation in (C) is generally from 40 to  100%; for aniline, which is preferably used as auxiliary  amine, it is preferably from 60 to 100%.  ally polyamine is invariably present in (C) in stoichiometric  proportion or in excess, referred to the acid.  It has proved useful to define the acid content of the  aqueous phase, independent of the varying amine content  arising 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 (that  is, an equal number of acid and amine equivalents) in a  volume of aqueous phase theoretically diminished by the  proportion of non-protonated amine, according to the for› mula  The virtually quantitative recirculation of the acid used  renders possible the use of costly acids such as, for example,  methanesulphonic acid, which in turn, owing to its low  tendency to corrode, permits the use of economical materials  in the apparatus of the process according to the invention.  thereof, optionally a part of the distillate from (X) can  bypass the washing stages and  be led to (Y) and employed  to regulate a varying water content in the individual extrac› tion stages.  "m  1  "ty"  mo! of 100% ;ritonated amine  $^{0 }$an  = vol. aqu. phase - vo~  Wlprotonated amine 