EP2513039A1

EP2513039A1 - Method for purifying compounds comprising amino groups

Info

Publication number: EP2513039A1
Application number: EP10794951A
Authority: EP
Inventors: Martin VÖLKERT; Burkhard Ernst; Wolfgang Siegel
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2009-12-17
Filing date: 2010-12-13
Publication date: 2012-10-24
Also published as: WO2011082976A1; JP2013514297A; US20120253076A1; US8785695B2; CN102712569A

Abstract

The invention relates to a method for purifying compounds (I) comprising amino groups, made of a polar phase A, wherein (I) is transformed into the corresponding imine (III) by reacting with an aldehyde or ketone (II), said imine being insoluble or slightly soluble in the polar phase A, and the imine (III) is subsequently transformed into a nonpolar phase B and separated from the phase A, and the compound comprising amino groups is subsequently reclaimed from the imine (III).

Description

Process for purifying amino group-containing compounds

The present invention relates to a process for the purification of amino group-containing compounds, in particular of alkylamines or alkyldiamines, which are present together with impurities and by-products in a polar phase. Particularly suitable is the process for purifying amino group-containing compounds which have been produced by fermentation and which are present at the end of the production process in an aqueous phase together with constituents of the fermentation medium.

BACKGROUND OF THE INVENTION

Amino group-containing compounds are important basic substances of the chemical industry. For example, find alkylamines and alkyl diamines use in the production of polyamides, polyureas or polyurethanes and copolymers thereof.

The fermentative or enzymatic production of alkyldiamines, for example of diaminopentane (DAP) by decarboxylation of lysine has been known for some time. Various methods for isolating the desired product from the fermentation broth are described.

Thus, for example, EP-A-1 482 055 describes the enzymatic decarboxylation of lysine in the presence of a dicarboxylic acid for adjusting the pH during the reaction. The DAP dicarboxylate obtained in the preparation is isolated by first destaining the concentrated solution with activated charcoal, concentrating and crystallizing out DAP dicarboxylate by cooling crystallization. JP 2004-222 569 describes the production of DAP using an L-lysine decarboxylase-expressing coryneform bacterium, adjusting the culture supernatant to pH 12 and extracting DAP with a polar organic solvent. JP 2004-000144 describes the preparation of DAP by reacting highly concentrated L-lysine monohydrochloride with L-lysine decarboxylase-expressing £. co // cells, adjustment of the reaction solution to pH> 13 and extraction of the reaction mixture. onsproduktes with a polar organic solvent and subsequent distillation.

WO 2009/92793 describes a process for the isolation of 1, 5-diaminopentane (DAP) from a DAP-containing fermentation broth, wherein the fermentation broth a) alkalized, b) thermally treated, c) DAP extracted with an organic extractant, and d ) DAP isolated from the separated organic phase.

However, in particular the processes known from the prior art, based on extraction of DAP with the aid of an organic solvent, have the disadvantage that the recycling of the valuable material is not optimal and in particular the extraction step is too slow and the overall process is therefore too time-consuming , which is a great disadvantage for an application of the production on an industrial scale.

SUMMARY OF THE INVENTION

The present invention is therefore based on the object of further improving the isolation of amino-containing compounds from fermentation broths. In particular, the yield of valuable material should be further increased and the time required for the isolation, in particular the solvent-based extraction, improved.

Surprisingly, this object has been achieved by providing a process for the purification of amino-containing compounds (I) from a polar phase A, wherein

i) (I) by reaction with an aldehyde or ketone (II) into the corresponding imine (III), which is not or hardly soluble in the polar phase A, and

ii) subsequently converting the imine (III) into a nonpolar phase B and iii) separating it from the phase A, and

from the imine (III) then the amino group-containing compound recovered. DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments

The invention relates to a process for the purification of amino-containing compounds (I) from a polar phase A, wherein

ü) then converting the imine (III) into a nonpolar phase B and iii) separating it from the phase A, and

iv) from the imine (III) then the amino group-containing compound recovered.

In a first specific embodiment of the process for purifying amino-containing compounds (I), alkyl derivatives which carry one or more, preferably two or three, amino functions are used as (I). Particular mention may be made here of alkyl derivatives having I to 10 C atoms, which may be linear, branched or in cyclic form. The process is used particularly advantageously for diaminoalkyls such as diaminopropane, diaminobutane, diaminopentane, diaminohexane, diaminoheptane and diaminooctane. In these compounds mentioned, the two amino groups may be in any arrangement with each other, but preferably in the 1, n-position for a diamino-n-alkyl, i.e. 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, etc. Such diaminoalkyls are prepared by methods known to those skilled in the art. A production process which is advantageously used in diamines such as 1,5-diaminopentane is the fermentative or enzymatic preparation.

In this case, the amino-containing compound (I) is usually present in an aqueous fermentation medium at the end of the preparation process, in which not only amino group-containing compound and optionally by-products and starting materials but also components of the nutrient medium and metabolic products are contained. Such an aqueous fermentation medium is referred to, for example, as polar phase A. Other examples of polar phases A are water or aqueous solutions or polar organic solvents such as lower alkyl alcohols or lower carboxylic acids or mixtures of these polar organic solvents with water.

The amino-containing compounds are generally readily soluble in aqueous phases, especially at low pH as a result of (partial) protonation.

The amino group-containing compounds (I) are converted into the corresponding imine (III) by reaction with an aldehyde or ketone (II). It is advantageous to choose (II) such that the (III) formed is not soluble or only sparingly soluble in the polar phase A in which (I) was present.

The reaction of (I) with (II) to (III) can be carried out in a wide temperature range, preferably temperatures between 20 and 50 ° C. The imine formation is improved by the addition of a base, since this shifts the equilibrium position to the side of (III).

As the aldehyde or ketone (II), any aliphatic or aromatic aldehydes and ketones capable of diimining with amino group-bearing compounds can be used. Advantageous compounds are those (II) which reduce the solubility of the imines (III) to be formed in the polar phase A, in which the amino-containing compounds are present.

Preferred as aldehyde or ketone (II) are benzaldehyde, valeraldehyde, cyclohexanone, methyl ethyl ketone, diisobutyl ketone, 2-octanone and acetone, benzaldehyde being particularly preferred for imine formation from 1,5-diaminopentane.

The aldehyde or ketone (II) is usually used in equimolar amounts or slight excess (1 -1, 5 preferably 1 -1, 1 equivalents) based on the amino groups in the amino-containing compounds (I) in order to obtain a quantitative Iminbil- (III).

However, since the aldehydes or ketones (II) can also serve as solvents for the imines (III), it is also possible to use (II) in large excess based on (I) and then the imines (III) formed in (II) as the solvent to separate. In a step iii) of the process according to the invention, the imine (III) formed is converted into a nonpolar phase B. Unpolar phase B is understood as meaning a phase which is not appreciably miscible with the polar phase A and which preferably forms a phase separation to phase A.

As nonpolar phase B, in addition to the abovementioned compounds (II) it is also possible to use nonpolar organic solvents such as ethers, medium-chain and longer-chain alcohols, hydrocarbons, ketones, aldehydes, aromatics. The non-polar phase B can already be added at the beginning of step ii); However, it is also possible to carry out step ii) without further solvent and to add a non-polar phase B only after imine formation (III) has taken place.

In a further step iii), the nonpolar phase B, which contains the imine (III), is separated from the polar phase A. This step is preferably carried out as extraction and can be operated continuously or discontinuously. Preferably, a discontinuous extraction at elevated temperature, d.i. between 30 ° and 70 ° C.

In a preferred embodiment, the extraction and / or the subsequent phase separation is carried out batchwise at elevated temperature, the temperature being limited by the boiling points of water and of the extractant or possibly forming azeotropes. With n-butanol as extractant, extraction and phase separation could e.g. be carried out at about 25-90 ° C or preferably at 40-70 ° C. For extraction, the two phases are stirred until the distribution equilibrium has settled, e.g. over a period of 10 seconds to 2 hours, preferably 5 to 15 minutes. Subsequently, the phases are allowed to settle until the phases have completely separated; this is preferably done over a period of 10 seconds to 5 hours, e.g. 15 to 120 or 30 to 90 minutes, especially at a temperature in the range of about 25-90 ° C or 40-70 ° C in the case of n-butanol.

The apparatus configuration of the extraction columns which can be used according to the invention can be determined by the person skilled in the art for the phases to be separated in the course of routine optimization work. Extraction columns are generally suitable without power input or extraction columns with power input, such. B. pulsed columns or columns with rotating internals. The expert may also, in the course of routine work, suitably select the type and materials of internals, such as trays, and column packings to optimize phase separation. The theoretical foundations of liquid-liquid extraction of small molecules are well known (see, for example, H.-J. Rehm and G. Reed, Eds., (1993), Biotechology, Volume 3 Bioprocessing, Chapter 21, VCH, Weinheim). The design of industrially applicable extraction columns is described, for example, in Lo et al., Eds., (1983) Handbook of Solvent Extraction, John Wiley & Sons, New York. The disclosure of the above textbooks is expressly incorporated by reference.

The phase separation necessary for a successful extraction can be positively influenced by changing the pH in the polar phase A. As a rule, an optimum mass transfer to the nonpolar phase B is achieved by pH values of> 12.

If desired, after separation of the imine (III) from the polar phase A, this can be further purified or concentrated at the imine stage, for example by distillation, chromatography or crystallization. In a last step iv), the imines (III) are used to recover the amino-containing compounds (I). This reverse reaction of imine formation is advantageously carried out with the addition of acid, in which case mineral acids or organic acids can be used. Particularly successful is the reverse reaction of imine formation with an equimolar addition of acid. Step iv) can be carried out by means of steam distillation.

A particular embodiment uses those acids which can form polyamides in a subsequent process with the amino-containing compounds (I). In this connection, the purification of the amino-containing compound (I) according to the invention simultaneously provides the monomeric "precursor" consisting of carboxylic acid and amino-containing compound (I) for the polyamides still to be prepared. Nonlimiting examples of suitable dicarboxylic acids are succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid. Preferred acids for this embodiment are in the case of the amino group-containing compound 1, 5-diaminopentane sebacic acid and adipic acid.

General information on fermentative 1, 5-diaminopentane production (DAP)

With regard to fermentative 1,5-diaminopentane production, reference is made to WO

Referenced 2009/92793. The experiments described below relate to the thus obtained by fermentation DAP.

The fermentation broths thus obtained, in particular containing L-lysine or DAP, usually have a dry matter content of from 3 to 20% by weight.

The fermentation broth is then further processed. Depending on the requirement, the biomass can be wholly or partly by separation methods, such. As centrifugation, filtration, decantation, flocculation or a combination of these methods are removed from the fermentation broth or completely left in her. A separation of the biomass is preferred. Subsequently, the fermentation broth with known methods, such as. B. with the aid of a rotary evaporator, thin film evaporator, falling film evaporator, by reverse osmosis, or by nanofiltration, thickened or concentrated. If necessary, any salts precipitated by the concentration can be separated, for example, by filtration or centrifugation. This concentrated fermentation broth can then be worked up in the manner according to the invention to obtain DAP. For the purposes of the present invention, such a concentration is possible, but not absolutely necessary. EXPERIMENTAL PART

Formation of imine for the purification of DAP

The imine formation (Figure 1 on the example of benzaldehyde) proceeds with elimination of water. Due to the pH regulation in the fermentation DAP is present in the broth as sulfate, which leads during the imine formation to a decrease in the pH and the Reaction on the educt side pushes back. This requires the addition of a base to complete the reaction.

Acid, water,

- 2 benzaldehyde

Fig. 1 Imine formation

With benzaldehyde, the spontaneous deposition of an organic product phase was observed. Basically, the reaction with the stoichiometric amount of benzaldehyde and then led to products of up to 98.5 FI .-% GC purity.

Upon extraction of an alkaline fermentation broth with methyl ethyl ketone, a mixture of imine, diaminopentane and water separated. The phase separation was exceptionally good in this experiment. Diaminopentane could be split back from the mixture by steam distillation with removal of the azeotrope via a column (but without a defined reflux); it was largely retained in the bottom.

Have been used successfully: cyclohexanone, methyl ethyl ketone (MEK), diisobutyl ketone, benzaldehyde, valeraldehyde, 2-octanone, methyl isoamyl ketone, methyl isobutyl ketone,

Imine formation with benzaldehyde

In an experiment to determine the amount of base required, 212 g of fermentation broth with a DAP content of 6% were admixed with 2 eq. Of benzaldehyde, and the product distribution and the pH were determined as a function of the amount of NaOH added (Fig.). For this purpose, a sample was taken after addition of the respective NaOH amount, the phases were separated and the aqueous and organic phases were analyzed by GC and quantitative HPLC.

It was found that after addition of 20 g NaOH the conversion was almost complete (benzaldehyde almost consumed, hardly any DAP in the water phase, GC of the upper phase 92.5% diimine); while the mixture had a pH of 9.4 set. Based on the PMDA contained in the fermentation broth, this corresponds to a number of uses of about 0.8 kg NaOH / kg DAPer. 100%), so it is slightly cheaper than in the extractive workup, but in the same order of magnitude.

An attempt to continuously extract the diimine from a fermentation broth in the rotary perforator was initially difficult because of the very sluggish distillation due to the high boiling point of benzaldehyde (180 ° C), but it was found that at pH 5.85 the addition of the benzaldehyde quickly stopped, practically no diimine could be extracted.

In the 4L miniplane reactor, the desired imine could be quantitatively isolated in high purity from 4 kg of fermentation broth (pH 13.5, DAP content 6.78% by weight) with addition of 2 equivalents of benzaldehyde. -% GC). The phase separation occurred spontaneously, but was complete only after 48 h - almost half of the product separated from the water phase only during this time. Apparatus: 41 miniplane reactor, with pH probe and pH meter

Approach: 4053.0 g DAP broth GC wt.% 6.78 corresponds to 274.8 g DAP

2.7 mol

572.9 g of benzaldehyde (5.4 mol, 2 eq)

Reaction: The fermentation broth was initially charged at RT (stirrer 400

U / min). Then the benzaldehyde dosed within one hour. Stirred overnight. pH 13. Did not change during the reaction.

Workup: The phases were separated. Org. Phase (753.4g), aqueous

Phase (3880g). 330g of this org. Phase separated after about 48h.

Analysis: GC: Method GC9-06-K.M Imine 98.4%

In general, in the formation of imine with benzaldehyde emulsified states are passed through, and only after a largely complete reaction, the phase separation is again acceptable.

In order to improve and accelerate the phase separation, a number of solvent experiments have been undertaken. For this purpose, alkaline fermentation broths were incubated at room temperature with a mixture of benzaldehyde and the solvent and the phases separated at elevated temperature (Table 1.

amount

Dft Solvent LM Temp Comments

1 cyclohexane 100% 50 ° C turbid phases - clarification after 48 h

2 Benzaldehyde 100% 60 ° C homogeneous, easily separable

3 Benzaldehyde 50% 60 ° C homogeneous, easily separable

very good phase separation. No more complete

4 2-octanol 100% 60 ° C conversion

very good phase separation, complete Um¬

5 1 -Hexanol 100% 60 ° C set

very good phase separation, complete Um¬

6 cyclohexanol 100% 60 ° C set

7 Phase separation acceptable at 60 ° C, slightly Mulm Table 1

For cyclohexane and toluene were also made experiments in which at 50

° C the phase separation time depending on the progress of the reaction - controlled by the metered amount of NaOH and the benzaldehyde used - was investigated.

After phase separation, the aqueous phase was in each case adjusted to pH 10 by addition of NaOH, benzaldehyde and solvent were added fresh, stirred for 15 minutes and the pH and phase separation times were measured.

With toluene, phase separation times between 27 and 54 seconds were observed, with the aqueous phases initially cloudy and almost clear at the end. The first organic phases contained a fairly stable foam, which did not decompose when the organic phases were combined.

With cyclohexane, the phase separation times were between 35 and 1 10 seconds. The

aqueous phases were generally less cloudy than with toluene, but even in these organic phases, quite stable foams were formed (34224/28).

In a further experiment with 4 eq. Benzaldehyde, the phase separation was investigated as a function of the added amount of NaOH. The phase separation remained slow until the pH of 9 was reached and all PMDA was converted to imine. This was the case with an amount of 65 g of NaOH (50%), based on the PMDA used, this corresponds to a use of 0.6 kg / kg of PMDA.

The organic phase remained foamy until the reaction was complete, then was

the phase separation, however, good. Cleavage of imines

The formation of imine in the presence of water is an equilibrium reaction, and so it was the original idea to accomplish the reverse reaction, that the liberated carbonyl could be removed as a steam-volatile compound by steam distillation to equilibrium. At the same time, the position of the equilibrium is dependent on the pH, which was already observed during the imine formation.

Benzaldehyde imines

By a stoichiometric amount of sulfuric acid, the cleavage of the imine succeeds smoothly in an aqueous mixture. The back-split benzaldehyde separates out as a separate organic phase and can be separated. In each case, 15-20 g of imine were distilled with water without further additives and in the presence of 0.5 g of sulfuric acid, Lewatit S 1468 (strongly acidic ion exchanger), Lewatit CNP80 (weakly acidic ion exchanger) and p-toluenesulfonic acid. In no case was a cleavage of the imine observed, which went beyond the expected by the catalyst acid level. The imine itself could not be distilled at 4 mbar at an oil bath temperature up to 240 ° C.

Since condensed water phases were present in the first orienting experiments, which could possibly influence the equilibration, in further experiments at 140-160 ° C. water was slowly added dropwise or steam was introduced. In this case, on the one hand 5 mol .-% sulfuric acid were used as catalyst and a comparative experiment carried out without a catalyst. The experiment with dropwise addition of water foamed so strongly that a part of the distillation bottoms was carried off into the distillate receiver. The attempts to introduce steam were, however, uncomplicated.

In the presence of 5 mol% sulfuric acid as catalyst, a mass decrease of the bottom from 17 to 86 g was observed, by GC the diimine to 98.2 wt .-%. The cloudy distillate (767 g) was extracted with methylene chloride; 4.9% diaminopentane and 7.1% diimine were found in the extract. Thus, about 10% of the diimine was cleaved and a further 10% distilled over. It could not be distinguished, whether that Despite the high boiling point of the diimine, the diimine is distilled over without decomposition of the undecomposed water or, if the distillate of the diaminopentane with the benzaldehyde in the initial charge causes the imine to regenerate. A control experiment for the steam distillation of DAP from aqueous solution showed that DAP should be retained by the attached Vigreux column practically completely.

Without added sulfuric acid 96% of the diimine used (1 17 g) were recovered, of which 17% in the distillate (900 g) were included. In order to be practically usable, the water-benzaldehyde azeotrope would have to be separated from the DAP by using a column with a higher separation efficiency, provided that the diimine is not overdriven by the water vapor without decomposition. No accumulation of free DAP was observed in the sump, but analysis is difficult because under HPLC conditions the diimine is partially cleaved back to free DAP, but the GC method does not separate PMDA and benzaldehyde because of their identical boiling point.

In summary, the benzylidene compound is apparently so strongly stabilized that the shift of the equilibrium to the educt side by steam distillation is not successful, even in the presence of catalytic amounts of acid. On the other hand, since the quantitative cleavage of acid was successful in the cleavage, it was advisable to use as the acid for the cleavage of the imine, the dicarboxylic acid with which the subsequent polymerization is provided. After addition of 1 eq of sebacic acid and steam distillation of the liberated benzaldehyde, the sebacate was retained in the bottom. This salt could be further purified by recrystallization from ethanol or butanol. The production of DAP adipate with adipic acid was also successful.

In a demonstration experiment, 175 g of imine (prepared from a fermentation broth) with 121 g of sebacic acid in 1200 g of water were subjected to azeotropic distillation. The remaining residue was taken up in ethanol, adjusted by azeotropic distillation to a water value of <0.3% and a content of about 30% and with inoculation at 50 ° C and cooling to 40 ° C in 2 h, and to 20 ° C crystallized in a further 2 h. During crystallization, the acetyldiaminopentane, which was contained in the imine with about 1.5%, was depleted by about 2/3. About 89% of a pale yellowish colored crystals were obtained. Recrystallization from ethanol resulted in no further improvement of the color. The difficulty was observed that excess sebacic acid precipitates at too low a temperature. An accurate determination of the imine content and the accurate adjustment of the stoichiometry are advantageous for achieving high purity.

Claims

claims

A process for the purification of amino group-containing compounds (I) from a polar phase A, wherein

iv) from the imine (III) then the amino group-containing compound recovered.

The method of claim 1, wherein the amino group-containing compound (I) is a dialkylamine.

3. The method of claim 2, wherein the dialkylamine is 1, 5-diaminopentane.

4. The method according to any one of the preceding claims, wherein the separation in iii) is done by an extraction process.

5. The method according to any one of the preceding claims, wherein used in i) benzaldehyde as (II).

6. The method according to any one of the preceding claims, wherein in iv) the recovery of (I) from (III) by addition of an acid causes.

A process according to claim 6, wherein the acid is added in equimolar amounts relative to (I).