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US 5,675,035 AGranted
Fractionation and purification of aromatic polyamine mixtures and the use thereof
AssigneeBayer Aktiengesellschaft
InventorsHartmut Knofel, Michael Brockelt
Life of this patent
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Abstract
The invention relates to a process for the fractionation and purification of aromatic polyamine mixtures and to their use.
Claims12
A process for the fractionation and purification of aromatic polyamine mixtures comprising:
- a) mixing the polyamine starting mixture in a first extraction stage with a two-phase system comprising
- (i) a hydrophobic solvent phase 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 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 operating on the countercurrent principle, and wherein said polyamine starting mixture is introduced into said first extraction stage with said hydrophobic solvent phase, with the proviso that the sum of amine equivalents introduced via polyamine mixture, hydrophobic solvent phase and aqueous phase always exceeds the number of acid equivalents introduced via said aqueous phase, and with the further proviso that a first aqueous phase and a first organic phase exit said first extraction stage,
- b) distilling said first organic phase in a first distillation stage into
- i) a first fraction consisting essentially of hydrophobic solvent and optionally auxiliary amine, and
- iii) a distillation residue consisting essentially of a first polyamine fraction,
- c) neutralizing said first aqueous phase by adding a base thereto and phase separating the resultant mixture into
- i) a second aqueous phase containing the acid in the form of its neutral salt, and
- ii) a second organic phase consisting essentially of polyamine and optionally auxiliary amine and/or small amounts of hydrophobic solvent
- d) separating said second organic phase in a second distillation stage into
- i) a distillate consisting essentially of hydrophobic solvent and auxiliary amine, and
- ii) a distillation residue consisting essentially of a second polyamine fraction, and
- e) recycling said first fraction as at least a portion of said hydrophobic solvent phase.
11 more elements
A process for fractionating aromatic polyamine mixtures wherein
- a) the initial polyamine mixture (A) is partitioned in a two-phase system consisting of (i) a hydrophobic solvent phase (B) which essentially consists of hydrophobic solvent and optionally an aromatic auxiliary amine which is virtually insoluble in water and has a boiling point at atmospheric pressure at least 20.degree. C. below the boiling point of the component with the lowest boiling point in the initial mixture and at least 20.degree. C. above the boiling point of the solvent, and/or polyamines, and (ii) an aqueous phase (C) essentially consisting of an aqueous solution of a strong acid and optionally an auxiliary amine which is at least partly in the salt form, and/or optionally polyamines which are at least partly in the salt form using an extraction stage (6) operating on the counterflow principle with thorough mixing of the phases, by introducing the initial polyamine mixture to extraction stage (6) with said hydrophobic solvent phase (B), with the proviso that the sum of the amine equivalents introduced to this two-phase system in streams (A), (B) and (C) always exceeds the number of acid equivalents introduced in stream (C), the organic phase (D) leaving this extraction stage being at least partly separated, optionally after passage through a washing stage (10), in the case of the preferred use of auxiliary amine, in a preferably multi-stage distillation stage (11), into a first fraction (E) which is re-used in extraction stage (6), essentially consisting of hydrophobic solvent and optionally auxiliary amine, optionally a second fraction (F) essentially consisting of auxiliary amine and optionally hydrophobic solvent and a first polyamine fraction produced as distillation residue (G), and aqueous phase (H) leaving the first extraction stage (6)
- b) passes, optionally at least partly via an upstream extraction stage (7)
- c) into a neutralization stage (8), the acid contained in the aqueous phase being neutralized with bases, preferably aqueous caustic soda solution and is then mechanically separated in a phase separation step into an aqueous phase containing the acid in the form of its neutral salts and an organic phase containing essentially polyamine, optionally auxiliary amine and optionally small amounts of hydrophobic solvent and
- d) the organic phase (J) produced in neutralization stage (8), optionally after passage through a washing stage (9), is worked up at least partly in distillation stage (12) into a distillation fraction (K) containing the amount of solvent contained in (J) or (J') and the auxiliary amine optionally contained in (J) or (J') and a second polyamine fraction produced as distillation residue (L).
1 more element
Dependencies are inferred from the claim text.