JPH11269132A - Production, of (s,s)-ethylenediamine-n,n'-disuccinic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply producing a high-purity product of a chelate compound having the biodegradability in high recovery ratio. SOLUTION: The crystallization is carried out in the presence of methanol by adding an inorganic acid thereto in a method for reacting L-aspartic acid with a dihaloethane in the presence of a basic metal compound in an aqueous solvent, producing a metal salt of (S,S)-ethylenediamine-N,N'-succinic acid and providing the (S,S)-ethylenediamine-N,N'-succinic acid from an aqueous solution of the resultant metal salt by the crystallization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to (S, S) -ethylenediamine-N, N'-disuccinic acid represented by the following structural formula (I) (hereinafter, ethylenediamine-N, N'-disuccinic acid is abbreviated as EDDS). The manufacturing method).

[0002]

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[0003] Specifically, it is obtained by reacting L-aspartic acid and dihaloethane in a basic aqueous medium (S,
(S, S) -Ethylenediamine-N, N 'from an aqueous solution of S) -ethylenediamine-N, N'-disuccinic acid metal salt
The present invention relates to an improvement in a method for crystallizing disuccinic acid. EDD
S has both practical chelating power and biodegradability, has no toxicity, and is used, for example, as a detergent builder.

[0004]

2. Description of the Related Art As a conventionally known chelating compound, for example, sodium tripolyphosphate has excellent chelating ability and has been used as a detergent builder. However, since it contains phosphorus, eutrophication of rivers or lakes is promoted. It is not currently used to contribute to the invite. Zeolite is often used as a detergent builder currently used, but it has low chelating power, and it is an inorganic substance and has no biodegradability,
Since it is insoluble in water, it has a problem of sticking to a drain pipe or the like. The most commonly known chelating compounds are ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NT
A). Although these have extremely stable chelating power, for example, when EDTA is poorly biodegradable and is released into the environment, it solubilizes heavy metals that are harmful to living organisms, so there is a concern that EDTA will be accumulated in the environment. Is done. Although NTA has biodegradability, it must be used with caution due to its toxicity.

[0005] Compared to these chelate compounds, EDDS
Has practical chelating power, biodegradability and no toxicity,
The demand is expected to increase in the future. EDDS has two asymmetric carbons and three optical isomers. Among these isomers, the S and S isomers have excellent biodegradability, but the R and R isomers are poor in biodegradability and have environmental concerns similar to EDTA. , Is not a compound that has a slower biodegradation rate than the S-isomer and easily biodegrades.

Various proposals have been made for a method of manufacturing an EDDS. For example, as a method of producing a racemic EDDS, a method of adding maleic acid to ethylenediamine (Zhurn Obshche)
i Khinii. , 49, 659 (1978)). As a method for producing S, S-EDDS, a method of adding L-aspartic acid to dibromoethane (Inorg. Chem., 7.2405 (196)
8)), a method of adding L-aspartic acid to dichloroethane (Chem. Zvesti., 20, 414 (1)
966)) or dicarbonyl compound (glyoxal)
A method for producing a Schiff base from carboxylic acid and aminocarboxylic acid (L-aspartic acid) followed by a reduction reaction (W
O96 / 32371) and the like.

[0007] The EDDS metal salt obtained by these methods is usually subjected to crystallization and purification by adding an inorganic acid such as hydrochloric acid to the reaction solution, collecting crystals precipitated in a specific pH range. However, it is difficult to isolate high-purity EDDS, and in many cases, crystallization is repeated several times. Regarding this crystallization, EDD
A method in which the S metal salt concentration is set low or acid precipitation is carried out while heating at 60 ° C. and cooled to room temperature (WO96 / 01803).
Has been proposed.

[0008]

As described above, if a high-purity EDDS is to be obtained by a conventional method, a complicated crystallization step is required, or a method such as repeated crystallization is required. As a result, there is a problem as an industrial production method, for example, the EDDS recovery rate also decreases. The present invention provides a high-recovery (high-yield) high-purity (S, S) -EDDS which is easy to contaminate (S, S) -EDDS and contains almost no raw material L-aspartic acid by a simple process. ) Is intended to provide an industrial production method.

[0009]

Means for Solving the Problems The inventors of the present invention have made intensive studies in view of the above-mentioned circumstances, and as a result, have found that the crystallization of (S, S) -EDDS is carried out by adding an inorganic acid in the presence of methanol. Was found to be able to be solved, and the present invention was completed. That is, the gist of the present invention is to react L-aspartic acid with dihaloethane in an aqueous solvent in the presence of a basic metal compound to obtain (S, S) -ethylenediamine-N,
A metal salt of N'-disuccinic acid is produced, and (S, S) -ethylenediamine-
A method for obtaining N, N'-disuccinic acid, characterized in that crystallization is carried out by adding an inorganic acid in the presence of methanol, and comprising (S, S) -ethylenediamine-N, N '.
A method for producing disuccinic acid. Hereinafter, the present invention will be described in detail.

[0010]

DETAILED DESCRIPTION OF THE INVENTION [Production of EDDS Metal Salt] EDD
The S metal salt is produced in an aqueous solvent using dihaloethane, L-aspartic acid and a metal compound as raw materials. As the dihaloethane, 1,2-dichloroethane and 1,2-dibromoethane can be preferably used, but 1,2-dichloroethane is preferable from the viewpoint of price, toxicity and the like.

The dihaloethane is preferably used in an amount of 0.5 to 0.7 mol per 1 mol of L-aspartic acid, and more preferably in a slight excess. When the amount is less than 0.5 mol, L-aspartic acid remains in a large amount in the reaction solution, significantly lowering the purification efficiency in crystallization, and is disadvantageous in cost. Is also not particularly effective, leading to an increase in by-products and an increase in cost, which is not preferable. As the aqueous solvent, water is preferable, and an organic solvent can be used in combination. For example, methanol coexisting during crystallization may be added in advance. However, the addition of methanol slightly accelerates the reaction rate, but on the other hand, it is usually preferable to carry out the reaction with a single solvent of water because it causes an increase in the amount of the reaction solution and an increase in the reaction pressure. When other glycols (such as ethylene glycol) are used, the reaction rate is still improved, but recovery is difficult, and it is preferable not to add them. The amount of the aqueous solvent is preferably used such that the concentration of the dialkali L-aspartate as a raw material is 5 to 50% by weight.

The metal compound is not particularly limited as long as it is a basic metal compound, and is preferably an alkali metal hydroxide or an alkaline earth metal hydroxide. Potassium, magnesium hydroxide, calcium hydroxide or mixtures thereof are mentioned. In this case, it is particularly preferable to use an alkali metal hydroxide and an alkaline earth metal hydroxide in combination. The use amount of the metal compound is preferably in the range of 2.0 to 4.0 mol per 1 mol of L-aspartic acid as long as it is an alkali metal hydroxide. If the amount is less than 2.0 mol, the dissolution of L-aspartic acid becomes insufficient, and the reaction rate decreases. Also 4.
If the amount is more than 0 mol, side reactions easily occur, which is not preferable.

The timing of adding the metal compound is not particularly limited as long as it is before the reaction, but L-aspartic acid and the metal compound are first introduced into the reactor, and the metal salt of L-aspartic acid is added as a metal salt. Therefore, it is preferable to adopt a method of introducing dihaloethane from the viewpoint of improving the solubility of L-aspartic acid and preventing heat generation. Reaction temperature is 50 ~
Perform at 140 ° C. At a temperature lower than 50 ° C., the reaction rate is remarkably reduced, and at a temperature higher than 140 ° C., the selectivity is reduced, and there is a concern that L-aspartic acid may be racemized. Although the reaction pressure depends on the temperature, the reaction is carried out at normal pressure or under pressure. Although the reaction time depends on other conditions, the reaction is carried out until the conversion of L-aspartic acid becomes 50% or more, preferably 70% or more, and is usually in the range of 0.5 to 50 hours.

[Crystallization] After completion of the reaction, unreacted dihaloethane in the reaction solution is distilled off before crystallization. Methanol to be added is added within a range of 10 to 200% by weight based on the reaction solution. If the amount is less than this, no sufficient effect is exhibited, and if added more, there is no effect, and only the amount of methanol to be recovered increases. As the inorganic acid used,
Hydrochloric acid or sulfuric acid is preferred, and is added little by little to the reaction mixture and the methanol mixture. At this time, if the concentration is high, there is a problem in safety such as excessive heat generation and vapor diffusion of methanol vapor. Therefore, it is preferable to use the acid diluted with water to about 3 to 30% by weight.

The crystallization temperature is not particularly limited.
There is no problem if it is carried out at about ℃, usually around room temperature. Heat is generated by the addition of the acid, in which case it can be adjusted by the amount of acid added,
The acid may be added while cooling. The acid addition time is 0.
The reaction is performed for a period of 5 to 10 hours, and the reaction solution is kept stirring at this time.

In the crystallization, an acid is added while confirming the pH, but crystals of (S, S) -EDDS precipitate around pH 4.0 to 5.0. Thereafter, in order to maintain the pH, a small amount of an acid is added until the pH is no longer increased. When the pH is made more acidic, the amount of unreacted L-aspartic acid precipitated increases, and the purity of (S, S) -EDDS decreases. In methanol co-crystallization, the (S, S) -EDDS recovery rate is almost 100% at around pH 4, and it is not necessary to add more acid.

The precipitated crystals are filtered as necessary by a conventional filtration method such as filtration under pressure, filtration under reduced pressure, and centrifugation. The obtained cake is preferably washed a few times with approximately the same amount of water. Thereafter, washing is performed with approximately the same amount of methanol, and draining is performed as much as possible. If this methanol washing is performed, not only the subsequent drying time is greatly shortened and the working efficiency is improved, but also impurities brought in with water can be reduced, and as a result, the purity of (S, S) -EDDS is improved. By washing the (S, S) -EDDS-containing cake with the same methanol as that used in the crystallization, the subsequent drying operation efficiency is greatly improved, and the used methanol does not azeotrope with water but has a boiling point of And it can be easily recovered and reused. From the filtered mother liquor, the used methanol can be easily recovered under reduced pressure or normal pressure, and the recovered methanol can be reused.

[0018]

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the examples unless it exceeds the gist thereof. Example 1 L-aspartic acid (manufactured by Wako Pure Chemical Industries, Ltd.) 13.
3 g (100 mmol) and 8.3 g (208 mmol) of sodium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) in water 30
The sodium hydroxide aqueous solution dissolved in ml is mixed while paying attention to heat generation to synthesize disodium L-aspartate. This aqueous solution was charged into a 100 ml autoclave, and then 2.9 g (50 mmol) of magnesium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) and 5.9 g (60 mmol) of 1,2-dichloroethane (manufactured by Wako Pure Chemical Industries, Ltd.) ) And reacted at 110 ° C. for 8 hours with stirring.
The pressure at that time was about 2 kg / cm ² · G.

After completion of the reaction, the reaction solution was withdrawn and the vessel was washed with 10 ml of water. An aliquot of the reaction solution was analyzed by high performance liquid chromatography to find that the conversion of L-aspartic acid was 78% and the (S, S) -EDDS yield was 7%.
2% (based on L-aspartic acid). Thereafter, a trace amount of unreacted 1,2-dichloroethane was distilled off under reduced pressure. The recovered reaction solution weighed 68 g and contained (S, S) -EDD
This was a cloudy solution containing 10.5 g (15.4% by weight) of S and 2.9 g (3.7% by weight) of L-aspartic acid.

In a 100 ml beaker, 20 g of the reaction solution obtained in the above reaction (containing 3.09 g of EDDS and 0.85 g of L-aspartic acid) was added, and 20 g of methanol was added. When the pH was measured with a pH meter while stirring, it was 9.89. The liquid temperature at this time was 22 ° C. 10% by weight sulfuric acid aqueous solution was added, pH
At 4.8, white crystals precipitated. The liquid temperature at this time is 29 ° C
Met. Thereafter, while adding 10% by weight of sulfuric acid little by little, the pH was kept at 4.3 to 4.8 to carry out crystallization. After the pH was no longer increased, the mixture was further stirred for 30 minutes to continue crystallization, and then the precipitated crystals were filtered and separated by suction filtration. After washing the cake three times with 15 ml of water, 15 m
After washing three times with 1 liter of methanol, 5.9 g of (S, S) -EDDS cake was recovered. When dried under the conditions of about 50 ° C. and 10 mmHg, the weight reached a constant weight in about 2 hours, and the weight was 3.09 g.

The obtained crystals were analyzed by liquid chromatography to find that (S, S) -EDDS was 3.03 g.
(Crystallization recovery rate: 98.1%), and the purity is 98.0%.
It was 1% by weight. 0.7% by weight (21
mg) L-aspartic acid, 1.7% water by weight, 5
It contained 0 ppm of sodium. From the filtered mother liquor, 18.9 g of methanol (recovery rate: 94.5%) was recovered.

Comparative Example 1 20 g of the same reaction solution as in Example 1 (3.09 g of EDDS,
L-aspartic acid (containing 0.85 g) was placed in a 100 ml beaker, and a 10% by weight aqueous sulfuric acid solution was added as in Example 1. White crystals precipitated at pH 4.0. The liquid temperature at this time was 34 ° C. Thereafter, the pH was maintained at 3.5 to 4.0 while adding 10% by weight of sulfuric acid little by little, and crystallization was performed. Thereafter, after the pH was no longer increased, crystallization was further performed for 30 minutes. At this time, the reaction liquid was a high-concentration slurry and the stirring efficiency was in a considerably poor state. Example 1
After performing suction filtration in the same manner as described above and washing three times with 15 ml of water, the cake was recovered. Weight is 6.6g, about 50 ° C,
It was dried under the condition of 10 mmHg. It reached a constant weight in about 2 days, and when weighed, it weighed 3.02 g.

Analysis of the obtained crystals by liquid chromatography revealed that the crystals contained (S, S) -EDDS (2.87 g, crystallization recovery rate: 92.9%), and the purity was 95.0% by weight. . As impurities, 2.1% by weight (63 m
g) L-aspartic acid, 5.2% water by weight, 80
ppm of sodium.

Comparative Example 2 20 g of the same reaction solution as in Example 1 (3.09 g of EDDS,
L-aspartic acid (0.85 g) was placed in a 100 ml beaker, and 20 g of water was added. 10 as in the first embodiment.
A weight percent aqueous sulfuric acid solution was added. White crystals precipitated at pH 4.0. The liquid temperature at this time was 30 ° C. Then 10
PH 3.5 to 4.0 while adding little by weight of sulfuric acid.
And crystallization was performed. After that, the crystallization was further performed for 30 minutes after the increase in pH was stopped. Example 1
After performing suction filtration in the same manner as described above and washing three times with 15 ml of water, the cake was recovered. Weight is 7.0 g, about 50 ° C,
It was dried under the condition of 10 mmHg. It reached a constant weight in about 2 days, and when weighed, it weighed 2.98 g.

When the obtained crystals were analyzed by liquid chromatography, they contained 2.85 g of (S, S) -EDDS (crystallization recovery rate: 92.2%) and had a purity of 95.6% by weight. . 1.6 wt% (48 m
g) L-aspartic acid, 2.9% water by weight, 70%
ppm of sodium.

[0026]

According to the method of the present invention, a chelating compound (S, S) -ED having biodegradability by a simple process.
A high-purity DS product can be obtained at a high recovery rate (high yield).

Claims (3)

[Claims] 1. An L-aspartic acid is reacted with a dihaloethane in an aqueous solvent in the presence of a basic metal compound to form a metal salt of (S, S) -ethylenediamine-N, N'-disuccinic acid. A method for obtaining (S, S) -ethylenediamine-N, N'-disuccinic acid by crystallization from an aqueous salt solution, characterized in that crystallization is carried out by adding an inorganic acid in the presence of methanol (S ,
A method for producing S) -ethylenediamine-N, N'-disuccinic acid. 2. The method for producing (S, S) -ethylenediamine-N, N'-disuccinic acid according to claim 1, wherein the dihaloethane is dichloroethane. 3. The method according to claim 1, wherein the metal compound is an alkali metal hydroxide.
A method for producing S) -ethylenediamine-N, N'-disuccinic acid.