7  5,663,424  8  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 •  The degree  of  protonation  in (C) is  generally  10-90%,  for  the aniline  used  preferably  as  auxiliary  amine it  is  preferably  25-70%.  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.  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 extrac› tion stage  (  4).  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.  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 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  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.  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.  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.  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).  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 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.  The  complete  separation  of  hydrophobic  solvent and  auxiliary  amine by  distillation  is not  necessary  when carry- ing out the  process according  to the  invention.  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  "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:  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  practically  quantitative  circuit operation  of the acid  used allows  the use of  expensive  acids such  as e.g. meth› anesulphonic  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  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 distil› lation.  The work-up  stages  (6)  and  (7)  serve to  separate  the  polyamine  fractions  which are  obtained  as  distillation  resi› dues 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.  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 quan- tity 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.  (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 final  extraction  stage  (5)  is  generally  designed  as a  multi-stage  extractor.  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.  "m I • ,,  mo! 100%  protonated amine  $^{0 }$anty  vol. of aqueous  phase - vol. of  unprotonated  amine 