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US 5,672,737 AGranted
Fractionation and purification of mixtures of aromatic polyamines and 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 mixtures of aromatic polyamines and to the use thereof.
Claims14
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 an aromatic auxiliary amine which is slightly soluble 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 optionally polyamine, and
- (ii) an aqueous phase consisting essentially of water, a strong acid and optionally an 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 aqueous 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 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 first distillation stage into
- i) a first fraction consisting essentially of auxiliary amine, and
- ii) 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 auxiliary amine, and
- d) separating said second organic phase in a second distillation stage into
- i) a distillate consisting essentially of auxiliary amine, and
- ii) a distillation residue consisting essentially of a second polyamine fraction.
10 more elements
A process for the fractionation and purification of mixtures of aromatic polyamines wherein
- a) the starting polyamine mixture (A) is partitioned in a two-phase system consisting of (i) a hydrophobic solvent phase (B) consisting essentially of aromatic auxiliary amine, which is sparingly soluble in water and whose boiling point under normal pressure is at least 20.degree. C. below the boiling point of the lowest-boiling component of the starting mixture, and optionally polyamines, and (ii) an aqueous phase (C) consisting essentially of an aqueous solution of a strong acid and optionally auxiliary amine present at least partially in the salt form, and/or optionally polyamines present at least partially in the salt form, with the aid of an extraction stage (7) operating according to the countercurrent principle, and with thorough mixing of the phases, the starting polyamine mixture preferably being introduced into the extraction stage (7) via the aqueous phase (C), with the proviso that, in this two-phase system, the amine equivalents introduced into the streams (A), (B) and (C) are always in excess of the number of acid equivalents introduced into the stream (C), and the organic phase (D) leaving this extraction stage is separated,
- b) optionally at least partially via an intermediate extraction stage (6) and/or
- c) optionally with separation of a partial stream before or after passage through the extraction stage (6), if appropriate, and recycling of the separated partial stream, via an upstream extraction stage (5), at least partially into the extraction stage (7),
- d) after passage through a washing stage and/or neutralization stage (10), in a distillation stage (11), which is optionally operated as a multiple stage, into a distillate fraction, consisting essentially of auxiliary amine, and a first polyamine fraction, obtained as the distillation residue (G),
- e) the aqueous phase (H) leaving the extraction stage (7) is introduced into a neutralization stage (8), the acid contained in the aqueous phase is neutralized with bases, preferably aqueous sodium hydroxide solution, and the resulting product 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 and auxiliary amine, and
- f) the organic phase (J) obtained in the neutralization stage (8) is optionally passed through a washing stage (9) and is at least partially worked up, in an optionally multiple distillation stage (12), into a distillate fraction (K), containing essentially auxiliary amine, and a second polyamine fraction, obtained as the distillation residue (L).
3 more elements
Dependencies are inferred from the claim text.