To readily fractionate and purify the subject mixture and produce isomers in the pure form and in the enriched form with a good separation efficiency by recycling and extracting the aromatic polyamine mixture in the multi-stage extraction in a two-phase system comprising a specific solvent phase and an aqueous phase according to the countercurrent principle and then distilling the organic phase in the multi-stage distillation.
An aromatic polyamine mixture is mixed with a two-phase system comprising a hydrophobic solvent phase consisting of (A1) a hydrophobic solvent and, as necessary, (A2) an aromatic auxiliary amine and (A3) a polyamine and an aqueous phase consisting of water, a strong acid, the component A2 and, as necessary, the component A3 to carry out a first extraction according to the countercurrent principle and provide a first aqueous phase and a first organic phase. The resultant first organic phase is then distilled in a first multi-stage distillation to afford respective fractions consisting essentially of the components A1 to A3. The first aqueous phase is extracted with a solvent phase consisting of the components A1 and A2 in a second extraction to provide a second aqueous phase and a second organic phase. The second organic phase is subsequently distilled in the multi-stage distillation in the same manner as that in the first multi-stage distillaton. The second aqueous phase is extracted with an organic phase consisting of the component A1 and, as necessary, the component A2 in a third expraction to afford a third aqueous phase and a third organic phase, which are respectively recycled to the first aqueous phase and the solvent phase in the second extraction and then fractionated and purified.
MIHIYAERU BUROTSUKERUTO
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