JPH07224014A - Production of l-aspartic acid-n-monopropionic acid and its alkali metallic salt and biodegradable chelating agent containing the same - Google Patents

Abstract

PURPOSE:To provide a method for producing L-aspartic acid-N-monopropionic acid and its alkali metallic salt in a higher yield and purity than those in a conventional method and obtain a biodegradable chelating agent containing at least one thereof as an active component. CONSTITUTION:This method for producing L-aspartic acid-N-monopropionic acid is to add acrylonitrile to L-aspartic acid under alkaline conditions, further add an alkali metallic hydroxide to the resultant reactional product, hydrolyze the reactional product, subsequently add sulfuric acid thereto and deposit a crystal. Further, the method for producing an alkali metallic salt of the L- aspartic acid-N-monopropionic acid is to react the deposited crystal with an alkali metallic salt or this method for producing a trialkali metallic salt of the L-aspartic acid-N-monopropionic acid is to evaporate the reactional product after the hydrolysis to dryness without adding the sulfuric acid thereto. Furthermore, this biodegradable chelating agent contains at least one of the L-aspartic acid-N-omnopropionic acid and its alkali metallic salt as an active component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing L-aspartic acid-N-monopropionic acid and its alkali metal salt from L-aspartic acid, and more specifically to L-aspartic acid containing acrylonitrile under alkaline conditions. A method of obtaining a crystal of L-aspartic acid-N-monopropionic acid by reacting, adding an alkali metal hydroxide to the reaction product and performing a hydrolysis reaction, and then adding sulfuric acid, A method for producing an alkali metal salt of L-aspartic acid-N-monopropionic acid by reacting crystals with an alkali metal hydroxide, and L-
L-aspartic acid-N is obtained by reacting aspartic acid with acrylonitrile under alkaline conditions, adding an alkali metal hydroxide to the reaction product to cause a hydrolysis reaction, and evaporating the reaction product to dryness. -A method for producing a trialkali metal salt of monopropionic acid.

The present invention also relates to L-aspartic acid-N
-It also relates to the use of monopropionic acid and its alkali metal salts as biodegradable chelating agents. L-
Aspartic acid-N-monopropionic acid and its alkali metal salts are used as a biodegradable chelating agent in a detergent composition,
Widely used in detergent builders, heavy metal sequestering agents, peroxide stabilizers, etc.

[0003]

2. Description of the Related Art Various methods for producing (±) -aspartic acid-N-monopropionic acid are conventionally known. For example, a method of adding sodium hydroxide to (±) -cyanoethylaspartic acid to carry out a hydrolysis reaction, and then reacting with hydrochloric acid (US Pat. No. 2,562,198).
No., J. Am. Chem. Soc., 1952, 74, 1942 (1952)),
There is a method of adding maleic anhydride to β-alanine (JP-A-56-107000).

As a method for producing (±) -cyanoethylaspartic acid, a method of reacting (±) -aspartic acid with acrylonitrile (US Pat. No. 2538)
024, J. Am. Chem. Soc., 1950, 72, 2599).

These prior arts are based on racemic (±)-, which is an equal mixture of biodegradable L-form and non-biodegradable D-form.
It relates to a method for producing aspartic acid-N-monopropionic acid, the product of which is not suitable for use as a biodegradable chelating agent.

Further, the conventional technique using once isolated (±) -cyanoethylaspartic acid is a two-tank reaction in which the process is complicated. Moreover, in the acid precipitation crystallization step of aspartic acid-N-monopropionic acid, there is a problem that the yield is low in addition to using hydrochloric acid which is not suitable for industrial processes.

Further, the prior art of adding maleic anhydride to β-alanine is useful as a detergent builder (±)-
It is known as a method for producing aspartic acid-N-monopropionic acid trisodium salt, but it also has problems in that the process is complicated and the purity and yield are low.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems of the prior art, and is an industry for L-aspartic acid-N-monopropionic acid and its alkali metal salts, which are excellent in biodegradability. The object of the present invention is to provide a process-friendly production method. Specifically, isolation and purification of synthetic intermediates from an inexpensive raw material can be omitted, and the desired L-asparagine can be obtained regardless of hydrochloric acid precipitation. An object is to provide acid-N-monopropionic acid and its alkali metal salt in high yield and high purity.

[0009]

Means for Solving the Problems As a result of intensive research to solve the above-mentioned problems, the present inventors have reacted L-aspartic acid with acrylonitrile under alkaline conditions and do not require isolation and purification. When an aspartic acid reaction solution is produced and an alkali metal salt is added to the reaction product for hydrolysis, water vapor is distilled off together with the produced ammonia, and the alkali metal ion concentration in the reaction solution is adjusted. As a result, the target L-aspartic acid-N-monopropionic acid crystals can be obtained in high yield by adding sulfuric acid as
It has been found that it can be obtained in high purity. Furthermore, it was found that the crystals were reacted with an alkali metal hydroxide to easily produce an alkali metal salt of L-aspartic acid-N-monopropionic acid. Moreover, after distilling off ammonia and water vapor, the reaction product is simply evaporated to dryness, and L-
It was found that a trialkali metal salt of aspartic acid-N-monopropionic acid can be obtained in high yield and high purity.
And, L-aspartic acid-obtained by these methods
The present invention has been achieved by finding that N-monopropionic acid and its alkali metal salt are chelating agents having extremely excellent biodegradability.

That is, the present invention is characterized in that L-aspartic acid is reacted with acrylonitrile under alkaline conditions, the reaction product is hydrolyzed by addition of an alkali metal hydroxide, and then crystals are obtained by sulfuric acid precipitation. Let L
-Aspartic acid-N-monopropionic acid production method, further, a method for producing an alkali metal salt of L-aspartic acid-N-monopropionic acid, characterized by reacting the crystals with an alkali metal hydroxide, and , L-aspartic acid is reacted with acrylonitrile under alkaline conditions, the reaction product is hydrolyzed by addition of an alkali metal hydroxide, and then the reaction product is evaporated to dryness. The present invention relates to a method for producing a trialkali metal salt of N-monopropionic acid, and a biodegradable chelating agent containing at least one of L-aspartic acid-N-monopropionic acid and its alkali metal salt as an active ingredient.

The present invention will be described in detail below.

The method of the present invention comprises an addition reaction step in which acrylonitrile is allowed to act on L-aspartic acid under alkaline conditions, a hydrolysis reaction step in which an alkali metal hydroxide is added to the reaction product, and sulfuric acid is added to the reaction product. Is added to isolate the desired L-aspartic acid-N-monopropionic acid, and an acid precipitation crystallization step is carried out, and L-aspartic acid-N is prepared by reacting the crystals with an alkali metal hydroxide.
-Consisting of an alkali metal monopropionate production process.
Alternatively, an addition reaction step in which acrylonitrile is allowed to act on L-aspartic acid under alkaline conditions, a hydrolysis reaction step in which an alkali metal hydroxide is added to the reaction product, and the reaction product is completely concentrated to obtain an objective. The L-aspartic acid-N-monopropionic acid trialkali metal salt is isolated by evaporation to dryness.

L-aspartic acid as a raw material of the present invention has an industrially available purity of 70% or more, preferably 8%.
A solid content of 5% or more is generally used, but an alkali metal salt obtained during the production or an aqueous solution of the alkali metal salt can be directly used. When an aqueous solution of a low-purity alkali metal aspartic acid salt is used, it is desirable that it does not contain ammonia, fumaric acid, or the like as impurities. In particular, the presence of ammonia in the addition reaction step ultimately leads to the by-product of β-alanine, so that the ammonia concentration is preferably 0.5% or less. In addition, the corresponding aspartic acid-N-monopropionic acid and its alkali metal salt can also be synthesized using racemic and D-form aspartic acid as raw materials. However, from the viewpoint of biodegradability of the product, L-form is preferably used as a raw material.

The alkaline conditions in the addition reaction step are as follows: direct use of alkali metal aspartic acid salt, or
This is achieved by the addition of alkali metal hydroxide. The type of alkali metal used is Li, Na or K,
Na or K is preferably used, and Na is particularly preferably used. The concentration of the reaction solution used is 5 to 75% by weight, preferably 10 to 60% by weight in terms of alkali metal aspartic acid salt. The reaction pH is 10 to 13,
The pH is preferably selected in the range of 10.5 to 12.5.

The amount of acrylonitrile used in the addition reaction step is from 0.9 to 1 mol of L-aspartic acid.
It is appropriately selected in the range of 1.5 times by mole, preferably 1.0 to 1.3 times by mole.

The addition method of acrylonitrile in the addition reaction step is to add acrylonitrile, which is not diluted with an organic solvent or water, into an alkaline aqueous solution of L-aspartic acid, and it is preferable to add it aliquotly or sequentially. Further, since this step is an exothermic reaction, a dropping rate capable of controlling the temperature is advantageous in the industrial process.

The temperature in the addition reaction step is 0-80.
℃, preferably in the range of 20 ~ 60 ℃, the reaction time is 1
It is good to carry out in the range of -24 hours, preferably 2-10 hours.

The by-products in the addition reaction step are almost absent except that a small amount of excess acrylonitrile remains.

As the cyanoethyl aspartic acid used in the hydrolysis step, the reaction product obtained in the above addition reaction step can be used directly. That is, when transitioning from the addition reaction step to the hydrolysis step, it can be carried out as a one-tank reaction without the need for operations such as isolation crystallization of cyanoethylaspartic acid and movement of the reaction tank as in the prior art. is there.

The alkali metal hydroxide used in the hydrolysis step is selected from Li, Na or K hydroxides, preferably Na or K hydroxides, and has a purity of 80% or more, preferably 95% or more. Solid product or concentration 10
It is necessary to use an aqueous solution of about 60% by weight, preferably 15 to 50% by weight, and always use an equimolar amount or more, preferably 1.0 to 1.3 times the molar amount of acrylonitrile used in the addition reaction step. It is advisable to add dropwise or to the addition reaction solution in a divided or sequential manner.

The temperature of the hydrolysis step is 70 to 110 ° C.
Preferably in the range of 90 to 105 ° C, the reaction time is 0.
It is good to carry out for 5 to 10 hours, preferably for 1 to 5 hours.

In the hydrolysis step, ammonia is produced in an equimolar amount to the acrylonitrile used in the addition reaction step with the progress of the reaction, but it can be recovered by evaporative distillation with steam. Further, by distilling off the water so that the concentration of the alkali metal ion in the reaction liquid becomes 3 to 30% by weight, preferably 5 to 15% by weight, with respect to the remaining water, the desired product in the subsequent acid precipitation crystallization step Can be obtained with high purity and high yield.

The sulfuric acid used in the acid precipitation crystallization step is selected from industrially available ones having a purity of 60 to 98%, and the amount thereof is 0.5 to the alkali metal hydroxide amount in the reaction solution. It is used in an amount of 1.0-fold mole, preferably 0.6-0.8-fold mole.

The temperature at the time of dropping sulfuric acid is preferably 10 to 100 ° C., preferably 40 to 80 ° C., and the dropping time is 0.5 to 6 hours, preferably 1 to 5 hours. good.

By-products in the hydrolysis and acid precipitation crystallization steps are almost absent in addition to sodium sulfate produced by the neutralization of sodium hydroxide with sulfuric acid when Na salts are used.

The desired product, L-aspartic acid-N-monopropionic acid, was reacted with 10 to 50 parts of the reaction product after the addition of sulfuric acid.
It is obtained by allowing to cool to 25 ° C, preferably 25 to 40 ° C, and suction-filtering the precipitated crystals.

In the conventional technique of using an acid other than sulfuric acid in the acid precipitation crystallization step, the amount of precipitation of the target crystal is small, and
Although there was a problem that the purity and yield of the target substance decreased because the inorganic salts were precipitated, according to the sulfuric acid acid precipitation method of the present invention, it is possible to obtain the target crystal in high purity and high yield. You can For this reason, for example, when NaOH is used as the alkali metal hydroxide, the salting-out effect of sodium sulfate generated during neutralization is considered. In fact, in the presence of sodium sulphate close to the saturated concentration, L-aspartic acid-
The solubility of N-monopropionic acid in the aqueous solution is significantly reduced, and an increase in the amount of crystal precipitation is observed. Then, by adjusting the amount of water distilled off in the hydrolysis step to the conditions as described above, the sodium sulfate concentration becomes close to the saturation concentration, while the salting out effect reduces the solubility of the target substance in the aqueous solution. It is considered that the amount of crystals of the product is increased and the target product can be obtained with high purity and high yield.

The obtained crystals of the target substance are of sufficiently high purity without recrystallization, except that the mother liquor containing a trace amount of sulfate group attached to the crystal surface is washed with a small amount of water.

In the production process of L-aspartic acid-N-monopropionic acid alkali metal salt, L-aspartic acid-
By reacting crystals of N-monopropionic acid with an alkali metal hydroxide in an aqueous solution and then evaporating the solution to dryness, an alkali metal salt of L-aspartic acid-N-monopropionic acid was obtained as a pure white solid. It is obtained quantitatively as a product. When a crystal of L-aspartic acid-N-monopropionic acid is reacted with a calculated amount of an alkali metal hydroxide, L
Aspartic acid-N-monopropionic acid mono-, di- and tri-alkali metal salts can be obtained. The tri-alkali metal salt of L-aspartic acid-N-monopropionic acid can also be obtained by a method in which the reaction solution is directly evaporated to dryness by omitting the acid precipitation crystallization step. It is industrially advantageous in terms of easiness.

The L-aspartic acid-N-monopropionic acid thus obtained and its alkali metal salts L-aspartic acid-N-monopropionic acid monosodium salt, disodium salt and trisodium salt Salts, monopotassium salts, dipotassium salts, tripotassium salts, monolithium salts, dilithium salts and trilithium salts are used as biodegradable chelating agents for detergent compositions, detergent builders, heavy metal sequestering agents, peroxide stabilizers. It can be widely used for These L-aspartic acid-N-monopropionic acid and alkali metal salts thereof may be used alone,
You may mix and use 2 or more types.

In an aqueous solution, L-aspartic acid-
By reacting N-monopropionic acid and / or its alkali metal salt with a calculated amount of alkali metal hydroxide, L
It is also possible to prepare the alkali metal salts of aspartic acid-N-monopropionic acid. For example, if 1 mol of sodium hydroxide is added to an aqueous solution containing 1 mol of L-aspartic acid-N-monopropionic acid monosodium salt, an L-aspartic acid-N-monopropionic acid disodium salt aqueous solution is obtained. To be

[0032]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to the following examples. Example 1 A reactor equipped with a stirrer, a thermometer, a dropping funnel, and a distillation apparatus was charged with 814 g (0.46 mol) of a 10% by weight aqueous disodium L-aspartate solution, and the mixture was stirred at 25 to 40 ° C.
27.0 g (0.51 mol) of acrylonitrile was added dropwise over 1 hour. Furthermore, after stirring at 25 to 30 ° C. for 8 hours, 22.0 g (0.55 mol) of sodium hydroxide was added to the reaction solution as a solid and dissolved. After the dissolution, when the temperature of the reaction solution was raised to 105 ° C., vigorous bubbling was observed, and stirring was continued while distilling out 514 g of ammonia water in 2.5 hours. Then, after confirming that the foaming of ammonia was completed, the reaction solution was allowed to cool to 50 ° C. Next, 102 g (1.04 mol) of 98% sulfuric acid was added to this reaction solution at an addition rate of 1.8 [g / min]. During this time, the temperature rose to 80 ° C. The reaction solution was allowed to cool to 33 ° C. again, and 101 g of precipitated white crystals of L-aspartic acid-N-monopropionic acid were isolated by suction filtration. The crystals were washed twice with 20 g of water at 0 ° C. L-aspartic acid-N-monopropionic acid (85.0 g, 0.41 mol, yield 9 after blast drying)
0.0%) is a uniform white crystal having a melting point of 204 to 205 ° C., and high performance liquid chromatography under various conditions, ¹ H-NMR,
As a result of analysis by ¹³ C-NMR and IR, the product purity is 99.9%.
No impurities were detected above. Also, in the platinum crucible
The residual ash content after combustion at 800 ℃ for 5 hours is 0.3% or less,
No inclusion of sodium sulfate was observed.

Comparative Examples 1 to 4 Other than using hydrochloric acid, phosphoric acid or nitric acid instead of sulfuric acid,
Acid precipitation crystallization was performed in the same manner as in Example 1. The results are shown in Table 1.

[0034]

Table 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Acid used 35% Hydrochloric acid 85% Phosphoric acid 90% Nitric acid Hydrogen chloride gas Acid usage 200g 194g 146g Aeration to pH 2 Crystallization temperature 0 ° C 10 ° C 0 ° C 0 ℃ Precipitated crystal amount (after drying) 46g 78g 55g 58g Residual ash content in 7% 32% 9% 12% L-aspartic acid-N-monopropio 46% 63% 54% 55% Actual yield of acid

Example 2 100 g (0.49 mol) of the pure L-aspartic acid-N-monopropionic acid crystals prepared according to Example 1 39.
It was dissolved in 200 g of ion-exchanged water together with 0 g (0.98 mol) of sodium hydroxide and then evaporated to dryness at a temperature of 105 ° C. for 5 hours to obtain a white solid. This was ground in a mortar to obtain 120 g of pure disodium L-aspartic acid-N-monopropionate (0.49 mol, yield 97%) as a uniform powder. A 25% by weight aqueous solution of L-aspartic acid-N-monopropionic acid disodium salt had a pH of 8.7.
It was suitable for use as a chelating agent for detergent builders and the like.

Example 3 Using 58.5 g (1.46 mol) of sodium hydroxide,
The procedure of Example 2 was repeated to obtain 131 g of pure L-aspartic acid-N-monopropionate trisodium.
(0.49 mol, yield 98%) was obtained as a uniform white powder. A 25% by weight aqueous solution of trisodium L-aspartic acid-N-monopropionate had a pH of 12.8 and was optimal for use as a chelating agent for detergent builders and the like.

Example 4 According to Example 1, 810 g (0.46 mol) of 10 wt% L-aspartic acid disodium aqueous solution was charged and stirred at 50 to 55 ° C.
Then, 24.3 g (0.46 mol) of acrylonitrile was added dropwise, and the mixture was further stirred for 1 hour. Next, 18.4 g (0.46 mol) of sodium hydroxide was dissolved in this reaction solution, and the temperature of the reaction solution was adjusted to 105 ° C.
Raised to. Continue stirring while distilling 514 g of ammonia water under atmospheric pressure to completely evaporate the reaction liquid to dryness.
Aspartic acid-N-monopropionic acid trisodium salt 12
5 g (0.46 mol, 100% yield) was obtained as a white solid. As a result of the analysis, the purity of the product was 97.5% or more, and trace amounts of 2 mol% or less of L-aspartic acid and 0.5 mol% or less of acrylic acid and fumaric acid were detected as impurities.

Example 5 The biodegradability test of L-aspartic acid-N-monopropionic acid synthesized in Example 1 was carried out under the following conditions according to the OECD test guideline 301C modified MITI test. The results are shown in Table 2. (Test conditions) Test sample concentration: 30 mg / l Activated sludge: Standard activated sludge Activated sludge concentration: 100 mg / l Test temperature: 25 ± 1 ° C Test period: 28 days

Comparative Example 5 and Comparative Example 6 Under the same conditions as in Example 5, the racemic and D-form aspartic acid-N-monopropionic acids were subjected to a biodegradability test. The results are shown in Table 2.

[0040]

[Table 2] Test results Example 5 Comparative example 5 Comparative example 6 Test sample L form racemic form D form HPLC analysis 100% 46% 7% TOC conversion 95.4% 62.3% 15.5% BOD conversion 86.5% 48.0% 4.8%

Example 6 The ability of L-aspartic acid-N-monopropionic acid synthesized in Example 1 to capture Ca ions was determined by J. Am. Oil. Chem. Soc.
It was measured according to the method described in 1970, vol. 48, page 682. The results are shown in Table 3.

[0042]

[Table 3] Test sample Ca ^{+ +} capture capacity (pH 10.0) Ca ^{+ +} capture capacity (pH 7.0) [CaCO ₃ mg / g conversion] [CaCO ₃ mg / g conversion] Example 1 compound 176 70 Aspartic acid 65 36 Glutamic acid 33 35 EDTA 389 385

[0043]

According to the method of the present invention, L-aspartic acid-N-monopropionic acid and its alkali metal salt can be obtained with high yield and high purity using inexpensive sulfuric acid. The present invention also has the following advantages. (1) It is possible to use L-aspartic acid, an alkali metal salt thereof, and an aqueous solution of an alkali metal salt thereof, which are inexpensively available as industrial raw materials. (2) Since almost no impurities are produced as by-products through the addition reaction step, the hydrolysis reaction step and the acid precipitation crystallization step, it is possible to carry out the reaction as a single tank without isolating the intermediate. (3) Industrially advantageous plant design is possible by using sulfuric acid which is less corrosive than hydrochloric acid used in the prior art. (4) Since there is almost no by-product, L-aspartic acid-can be obtained by omitting the acid precipitation crystallization step and simply evaporating the reaction solution to dryness.
It is possible to obtain the trialkali metal salt of N-monopropionic acid in high yield. (5) It is possible to produce highly pure mono-, di- and tri-alkali metal salts of L-aspartic acid-N-monopropionic acid.

Claims (4)

[Claims] 1. L-aspartic acid is reacted with acrylonitrile under alkaline conditions, the reaction product is hydrolyzed by adding an alkali metal hydroxide, and then crystals are obtained by sulfuric acid precipitation. Aspartic acid-
A method for producing N-monopropionic acid. 2. L-aspartic acid-N-obtained by reacting L-aspartic acid with acrylonitrile under alkaline conditions, hydrolysis of the reaction product by addition of an alkali metal hydroxide, and sulfuric acid precipitation. A method for producing an alkali metal salt of L-aspartic acid-N-monopropionic acid, which comprises reacting monopropionic acid with an alkali metal hydroxide. 3. L-aspartic acid is reacted with acrylonitrile under alkaline conditions, the reaction product is hydrolyzed by addition of an alkali metal hydroxide, and the reaction product is evaporated to dryness. -Aspartic acid-
A process for producing a trialkali metal salt of N-monopropionic acid. 4. A biodegradable chelating agent containing, as an active ingredient, at least one of L-aspartic acid-N-monopropionic acid and an alkali metal salt thereof.