JPH1059912A - Method for producing aspartic acid derivative - Google Patents

Abstract

(57) [Summary] [Problem] An agent for textile dyeing as a biodegradable chelating agent,
Industrial use of aspartic acid-N, N-diacetate alkali salts widely used in detergent builders, metal surface treatment complexing agents, electroless plating complexing agents, photographic agents or bleaching aids for paper pulp. To provide a method for producing in high yield and high purity. SOLUTION: After reacting aspartic acid or aspartic acid monoacetic acid with a cyanomethylating agent in an aqueous medium to form a cyanomethylated product, the cyanomethylated product is hydrolyzed in the presence of a base component to give aspartic acid -N, N- In the method for producing alkali diacetates, the amount of cyano ions contained in the cyanomethylated product is set to 1.0% or less when the cyanomethylated product is hydrolyzed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an aspartic acid
The present invention relates to a method for producing alkali N, N-diacetates. Aspartic acid-N, N-diacetate alkali salts are biodegradable, fiber dyeing agents, detergent builders, metal surface treatment complexing agents, electroless plating complexing agents, photographic agents or paper. It can be used as a bleaching aid for pulp.

[0002]

2. Description of the Related Art As a method for industrially obtaining an aspartic acid-N, N-diacetate alkali salt as an aspartic acid derivative, monochloroacetic acid or monobromoacetic acid is allowed to act on a salt of aspartic acid in the presence of a base component ( Soviet Patent No. 482438) is known. However, this method is not industrially advantageous because a large amount of highly corrosive halogen waste liquid is produced.

[0003] As another production method, aspartic acid is reacted with a nitrile compound to obtain an amide compound.
Further hydrolyzing to obtain the desired product (Japanese Patent Application No. 7-377)
No. 60), but the process is long and the operation is complicated, and there is a problem in productivity.

[0004] As a method of hydrolyzing a cyanomethyl compound with a base without passing through an amide compound, a method of reacting aspartic acid with a nitrile compound and hydrolyzing in the presence of a base to obtain a target compound, and a method of hydrolyzing in the presence of a base A method of directly obtaining the target compound by reacting aspartic acid with a nitrile compound (JP-A-7-89913, German Patent No. 421171)
No. 3) has been proposed.

[0005] In these methods, although the process is short, not only nitrilotriacetic acid (hereinafter referred to as NTA), which is a reaction by-product, is generated in large quantities, but the target substance is easily decomposed by heating or the like, and fumaric acid And iminodiacetic acid (hereinafter referred to as IDA), it was difficult to obtain a high-purity target product. For this reason, these reaction solutions cannot be used as they are as alkali salts which are often used in the form of utilization. In order to obtain a high-purity alkali salt, it is necessary to isolate and purify it in the form of an acid and then to convert it back to an alkali salt, which causes a problem that the process becomes longer.

[0006] In any of the methods, the coloring of the reaction solution is intense, and a sufficient decoloring effect cannot be obtained only by using activated carbon as it is. Further, when hydrogen peroxide is allowed to act directly on the reaction solution, not only a sufficient decoloring effect cannot be obtained, but also the coloring proceeds with time.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an NT
It is an object of the present invention to provide an industrially advantageous production method capable of obtaining a high purity and colorless aspartic acid-N, N-diacetate alkali salt having a small amount of by-products such as A in high purity.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, reacted aspartic acid or aspartic acid monoacetic acid with a cyanomethylating agent in an aqueous medium to obtain a cyanomethylated product. After that, the amount of cyanide ions is reduced to 1.0% or less and hydrolysis is performed, whereby the generation of by-products can be suppressed. Aspartic acid-N, N-diacetate alkali salts having high purity and no color can be obtained with high yield. Thus, the present invention was completed.

That is, the present invention provides a method comprising reacting aspartic acid or aspartic acid monoacetic acid with a cyanomethylating agent in an aqueous medium to form a cyanomethylated product, and hydrolyzing the cyanomethylated product in the presence of a base component to obtain aspartic acid. In the method for producing -N, N-diacetate alkali salts, the amount of cyano ions contained in the cyanomethylated product is reduced to 1.0% or less during the hydrolysis of the cyanomethylated product. -A method for producing alkali diacetates. "

[0010] Further, the reaction solution after the cyanomethylation reaction and before the hydrolysis reaction is aerated with an inert gas or air and / or degassed under reduced pressure to reduce the amount of cyano ions contained in the cyanomethylated product. It has been found that the content can be reduced to 1.0% or less.

[0011] Further, by degassing under reduced pressure or passing through air or an inert gas during the hydrolysis reaction, or by simultaneously performing the two, it is possible to significantly reduce by-products such as NTA, fumaric acid and IDA. I found it.

Further, the pH of the hydrolysis reaction completed solution is adjusted to 12
The decolorizing effect by the activated carbon can be significantly increased by lowering it below, and by performing hydrogen peroxide treatment with the residual cyanide concentration of the hydrolysis reaction finished liquid reduced to 100 ppm or less, there is no recoloring after decolorization It has been found that good effects can be obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. An object of the present invention is to obtain an aspartic acid-N, N-diacetate alkali salt. Alkali salts include at least one of the four carboxyl groups in one molecule of aspartic acid-N, N-diacetate.
And salts thereof in which one hydrogen atom is replaced by an alkali metal and mixed salts thereof. The alkali metal is L
i, Na, K, Rb, Cs, etc., wherein the alkali salts are monolithium salts, dilithium salts, trilithium salts,
Tetralithium salt; monosodium salt, disodium salt, trisodium salt, tetrasodium salt; monopotassium salt, dipotassium salt, tripotassium salt, tetrapotassium salt;
Includes rubidium salts, tri-rubidium salts, tetra-rubidium salts; mono-cesium salts, di-cesium salts, tri-cesium salts, tetra-cesium salts and the like, and mixed salts thereof.

In the method of the present invention, first, aspartic acid or aspartic acid monoacetic acid is dispersed or dissolved in an aqueous medium. When the raw material is a salt with a base, aspartic acid, aspartic acid monoacetic acid, aspartic acid-N, N-diacetic acid, or
It is preferable to add an inorganic acid such as sulfuric acid or hydrochloric acid.

Aspartic acid used in the present invention may be a commercially available one, but the S-form is more preferable than the racemic form from the viewpoint of biodegradability. As the aspartic acid monoacetic acid, a product obtained by a known method can be used. Further, in the present invention, a compound in the form of a salt in which the acid of aspartic acid or aspartic acid monoacetic acid as a raw material is partially or entirely neutralized with a base can also be used.

As the aqueous medium, a mixed solvent of water and a water-soluble organic solvent such as acetonitrile, methanol, ethanol, isopropanol, isobutanol, dioxane, and THF can be used. An arbitrary mixing ratio can be used, but an aqueous solvent is most preferable.

Then, aspartic acid or aspartic acid monoacetic acid is added to a slurry or a solution in which the aspartic acid or aspartic acid monoacetic acid is dispersed at 20 to 70 ° C., preferably 30 to 45 ° C.
Then, a cyanomethylating agent is added and reacted to obtain a cyanomethylated product. The cyanomethylating agent used in the present invention is either hydrocyanic acid and formalin or glycolonitrile, and from the viewpoint of reactivity, hydrocyanic acid and formalin are preferred. When the cyanomethylating agent is hydrocyanic acid and formalin,
Equimolar or small excess of formalin is added simultaneously with hydrocyanic acid, or equimolar or small excess of formalin is added followed by hydrocyanic acid. The amount of hydrocyanic acid used is 1.9 to 2.2 mol, more preferably 2 to 1 mol of aspartic acid.
~ 2.1 moles is preferred. When aspartic acid monoacetic acid is used, half the amount when aspartic acid is used is used. In the case of glycolonitrile, it is reacted as it is or as an aqueous solution. The amount of glycolonitrile used is 1.9 to 3 moles per mole of aspartic acid,
More preferably, 2 to 2.5 mol is used. When aspartic acid monoacetic acid is used, half the amount when aspartic acid is used is used as in the case of hydrocyanic acid. In order to carry out the cyanomethylation reaction completely, after the addition of the cyanomethylating agent, the temperature is preferably 30 to 70 ° C., preferably 40 to 70 ° C.
The aging reaction is preferably performed at about 50 ° C. for about 3 hours.

Next, the cyanomethylation reaction completed solution is added to an aqueous solution of a base while maintaining the temperature at 20 to 90 ° C., preferably 40 to 90 ° C., more preferably 60 to 80 ° C., to carry out a hydrolysis reaction. After the addition is completed, further at 20 to 90 ° C, preferably 40 to 90 ° C, more preferably 60 to 90 ° C,
The aging reaction is performed for 1 to 5 hours. The amount of cyano ions contained in the cyanomethylated product subjected to the hydrolysis reaction is 1.0% or less, preferably 0.5% or less, based on the cyanomethylated product.
Or less, more preferably 0.3% or less. Usually, the reaction is carried out in an excess of 10% or less, more preferably 5% or less, based on the theoretical equivalent amount of the cyan compound charged in the cyanomethylation reaction so that the amount of the remaining cyan ions does not become excessive. Is good. When the amount of cyano ion with respect to the cyanomethylated product becomes 1.0% or more, the cyanomethylated reaction ending solution is heated to a temperature of 1 before the hydrolysis reaction.
Degas at 5 to 50 ° C. under a reduced pressure of 93300 Pa or less, or supply air or an inert gas at 1 m ³ / hour / reaction solution 10
It is preferable to remove excess cyanide by aerating m ³ or more, or performing deaeration and aeration simultaneously.

The base used in the hydrolysis has an aqueous solution pH of 1
As long as the base is 2 or more, any of organic and inorganic bases can be used, but from the viewpoint of the method of use and operability of the product, hydroxide of alkali metal such as lithium hydroxide, sodium hydroxide, potassium hydroxide, etc. It is preferable to use a substance. Usually, sodium hydroxide or potassium hydroxide is preferably used because the resulting composition is a sodium or potassium salt of aspartic acid-N, N-diacetate in a commonly used form.

The amount of the base used is the amount A necessary to neutralize the acid of aspartic acid or aspartic acid monoacetic acid,
Assuming that the amount B required to neutralize the acid generated by hydrolysis of the cyanomethyl compound used and the amount D of the base used are represented by the following formula (1).

D = (A + B) × C (1) Here, C may be any value in the range of 1.01 to 1.5, and more preferably, in the range of 1.03 <C <1.2. Is selected. When C is in this range, the amount of base used D
Is an amount sufficient for the hydrolysis to occur smoothly,
The excess base component after the reaction is completed is also reduced.

The ammonia gas generated during the hydrolysis reaction is removed to the outside of the system by deaeration at a reduced pressure of 93300 Pa or less, more preferably 66600 Pa or less, by aerating air or an inert gas, or by deaeration. Aeration is performed at the same time. The amount of aeration and ventilation of air or inert gas needs to be sufficient to discharge ammonia gas generated by hydrolysis. Usually, it is good to ventilate the gas by 0.7 to 10 times, preferably 1.5 to 5 times the amount of generated ammonia. Further, it is preferable to make bubbles fine and sufficiently agitate so that the gas is sufficiently transferred to the gaseous phase during the ventilation. As the inert gas, nitrogen gas, argon, neon, helium and the like can be used, but nitrogen gas is preferable from an economic viewpoint.

In this manner, a highly pure alkali salt of aspartic acid-N, N-diacetate with little coloring can be obtained. If necessary, the following decolorizing operation is performed. A method for decolorizing the obtained hydrolysis reaction completed solution can be selected depending on the degree of coloring and the device used. In the case of using molecular oxygen, any of oxygen, oxygen-enriched air, and air is used, but air is preferred from the viewpoint of economy and safety. The ventilation volume is 1
3000-5000 kg of hydrolysis reaction end solution
cc / min is preferred, and the treatment temperature is 20-80 ° C, preferably 40-70 ° C.

When decoloring with activated carbon, an acid component such as aspartic acid-N, N-diacetic acid is added to the hydrolysis reaction completed solution, and the pH is from 4 to 12.5, more preferably from 10 to 10%.
Adjust to ~ 11.5. The value of the adjusted pH may be 4 or less, but if the pH is lower than necessary, undesired aspartic acid-N, N-diacetic acid may precipitate during the decolorization treatment. When the reaction solution is used as it is as a product of an aqueous solution of an alkali salt without isolating it as a free acid, a drastic decrease in pH is caused by excessive addition of an acid component, which is not preferable.

Next, 0.5 parts by weight based on the dissolved
Add activated carbon in an amount of 10%, preferably 1-5%,
After stirring for about 30 minutes, the activated carbon is filtered to obtain a clear reaction solution. By this decolorizing operation, the color tone of the reaction solution becomes APHA 100 to 150.

If necessary according to the purpose of use, the pH of the reaction solution is adjusted using aspartic acid-N, N-
PH of 50% aqueous solution, 12
Adjust to ~ 12.5.

As the acid used for adjusting the pH during the treatment with activated carbon, commercially available hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, glycolic acid, lactic acid, oxalic acid, succinic acid, malic acid,
Aspartic acid, acidic ion exchange resin, aspartic acid-N, N-diacetic acid, aspartic acid monoacetic acid and the like can be used. If the use of the product does not favor the use of an inorganic salt, acetic acid, oxalic acid, aspartic acid, aspartic acid-N, N-diacetic acid, and aspartic acid monoacetic acid are used. Use hydrochloric acid or sulfuric acid when inorganic salts are acceptable. When a product with higher purity is required, aspartic acid-N, N-diacetic acid or an acidic ion exchange resin is preferred. Also, aspartic acid-
In the case where N, N-diacetic acid is to be isolated as crystals in the form of a free acid, sulfuric acid is preferred from the viewpoint of corrosiveness and operability.

The activated carbon used in the present invention may be in any form such as a commercially available powder or sphere.

Further, the remaining cyan ion is 100 pp.
m or less, preferably 50 ppm or less, can be decolorized by performing a treatment with active oxygen such as hydrogen peroxide or ozone. Hydrogen peroxide is commercially available 3
A substance having a concentration of 0 to 35% can be used as it is, or a substance having a low concentration can be used. In the case of ozone, a commercially available ozone generator may be used. Its usage is
Depending on the degree of coloring of the reaction solution, the amount of hydrogen peroxide or ozone is preferably 0.01 to 1.5% by weight, preferably 0.05 to 1.0% by weight, based on the weight of the solvent.

In this manner, a high-quality alkali salt of aspartic acid-N, N-diacetate having a low NTA content of 1% or less and no coloring can be obtained.

[0031]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 133.1 g of aspartic acid and 130 g of water were charged into a reaction vessel and dispersed. Next, 169 of 37% formalin aqueous solution
g of hydrocyanic acid, and 55.7 g of hydrocyanic acid was added dropwise over about 1 hour while controlling the reaction temperature to 45 ° C. or lower.
After completion of the dropwise addition, the mixture was stirred and reacted at 40 to 45 ° C. for 3 hours. After the ripening, the cyan ion concentration was 0.25%. A 48% aqueous solution of caustic soda 3
In 66.7 g, while degassing under reduced pressure to 40,000 Pa,
The reaction temperature was maintained at 70 ° C. or lower, and the mixture was added dropwise over about 3.5 hours. After completion of the dropwise addition, an aging reaction was performed at 70 ° C. for 2 hours while degassing under reduced pressure was continued at 40000 Pa. Add aspartic acid-N, N-diacetic acid to the reaction completed solution and add p
After adjusting to H11, 10 g of activated carbon was added, and after stirring for 30 minutes, the activated carbon was filtered off to obtain an aqueous solution of aspartic acid-N, N-diacetate tetrasodium salt. The color tone at this time is AP
HA is 100 or less, the yield of aspartic acid-N, N-diacetate tetrasodium salt is 96%, and the amount of impurities is aspartic acid-N, N-diacetate tetrasodium salt, aspartic acid monoacetate sodium salt 3%, IDA sodium salt 0.6%, NTA sodium salt 0.4%, sodium fumarate sodium salt trace. The obtained aqueous solution of aspartic acid-N, N-diacetate tetrasodium salt was dried with a spray dryer to obtain a slightly yellow powder. From the results of content analysis and differential thermal analysis by high performance liquid chromatography, the dried powder was found to be aspartic acid-N, N-diacetate 4 as a monohydrate.
Sodium salt content 94%, NTA sodium salt 0.4%
Met.

Example 2 In a reaction vessel, 133.1 g of aspartic acid and 130 g of water were charged and dispersed. Next, 169 of 37% formalin aqueous solution
g, and 55.7 g of hydrocyanic acid was added dropwise over about 1 hour while controlling the reaction temperature to 45 ° C. or lower. After completion of the dropwise addition, the mixture was stirred and reacted at 40 to 45 ° C. for 3 hours. After the ripening, the cyan ion concentration was 0.30%. next,
A 48% aqueous solution of caustic soda 3 was placed in a reaction vessel equipped with a diffuser.
66.7 g was charged, and while the reaction temperature was maintained at 70 ° C. or lower while blowing air at a rate of 1000 cc / min from the air diffuser, the cyanomethylation ripening reaction completed solution was added in 3 hours. After completion of the addition, the mixture was subjected to an aging reaction at a reaction temperature of 70 ° C. for 12 hours while continuously aerating the air at 3000 cc / min.
The color tone of the reaction-terminated liquid was APHA150, and the yield of aspartic acid-N, N-diacetate tetrasodium salt was 94%. The amount of impurities is aspartic acid-N, N-diacetate 4
Based on the sodium salt, aspartic acid monoacetate sodium salt 4%, IDA sodium salt 0.8%, NTA sodium salt 0.6%, and fumaric acid sodium salt 0.1%.

Example 3 A reaction vessel was charged with 133.1 g of aspartic acid and 130 g of water and dispersed. Next, 167 of 37% formalin aqueous solution
g of hydrocyanic acid, and the reaction temperature was raised to 45 ° C.
It dripped over about 1.0 hour, controlling below. After the completion of the dropwise addition, the reaction was further stirred at 40 to 45 ° C. for 3 hours. After the ripening, the cyan ion concentration was 0.28%. Next, 366.7 g of a 48% aqueous sodium hydroxide solution was charged into a reaction vessel equipped with an air diffuser, and 1000
While blowing the nitrogen gas at a rate of cc / min, the reaction temperature was kept at 70 ° C. or lower, and the cyanomethylation ripening reaction completed solution was added in 3 hours. After completion of the addition, the aging reaction was carried out at a reaction temperature of 70 ° C. for further 3 hours while continuing aeration of nitrogen gas at 3000 cc / min. Formalin was added in an amount 1.2 times as much as the amount of free cyan contained in the reaction-terminated liquid, and subjected to cyanide decomposition at 70 ° C. for 2 hours. The residual cyan concentration in the processing solution is 10
After confirming that the concentration was 0 ppm or less, 5 g of 10% hydrogen peroxide solution was added, and the mixture was stirred for 1 hour.
An aqueous solution of N, N-diacetate tetrasodium salt was obtained. The color tone of this solution is APHA 100 or less, and aspartic acid-
The yield of N, N-diacetate tetrasodium salt was 95%. The amount of impurities is aspartic acid-N, N-diacetate 4
Based on the sodium salt, aspartic acid monoacetic acid sodium salt 4%, IDA sodium salt 0.7%, NTA sodium salt 0.5%, and fumaric acid sodium salt 0.01%.

Example 4 Aspartic acid monoacetic acid monosodium salt 2 was placed in a reaction vessel.
31 g and 340 g of water were added and dissolved, and the pH was adjusted with sodium hydroxide.
Adjust to 5.2. Next, 119.6 g of a 50% aqueous solution of glycolonitrile was added dropwise over about 2.0 hours while controlling the reaction temperature to 45 ° C. or lower. After dripping, 4
The reaction was further stirred at 0 to 45 ° C for 3 hours. Further, nitrogen gas was blown at 40 ° C. at a rate of 3000 cc / hour for 2 hours, and the cyan ion concentration became 0.1%. Next, 48
40000P in 283.3g of 28% aqueous sodium hydroxide solution
The reaction temperature was kept at 70 ° C. or lower while deaeration was carried out under reduced pressure over a period of about 3.5 hours. After dropping, 40
The aging reaction was performed at 70 ° C. for 2 hours while continuing the deaeration under reduced pressure at 000 Pa. 98% sulfuric acid was added to the reaction-terminated liquid to adjust the pH to 11, and then 10 g of activated carbon was added.
After stirring for 0 minutes, the activated carbon was filtered off and aspartic acid-N, N
-An aqueous solution of tetraacetic acid tetrasodium salt was obtained. The color tone at this time was APHA 100-150, and aspartic acid-N, N-
The yield of tetrasodium diacetate was 93%. The amount of impurities is aspartic acid-N, N-diacetate tetrasodium salt, aspartic acid monoacetate sodium salt 5%,
IDA sodium salt 1.0%, NTA sodium salt 0.1%
8%, trace of sodium fumarate.

Example 5 A reaction vessel was charged with 133.1 g of aspartic acid and 130 g of water and dispersed. Next, a 37% formalin aqueous solution 170
g, and while controlling the reaction temperature to 40 ° C. or lower, 59 g of hydrocyanic acid was added dropwise over about 1 hour. After completion of the dropwise addition, the mixture was stirred and reacted at 40 to 45 ° C. for 3 hours. After the ripening, the cyan ion concentration was 2%. The cyanomethylation maturation reaction completed solution was degassed at 40 to 45 ° C. under a reduced pressure of 60000 Pa for 2 hours to reduce the amount of cyan ions to 400 pp.
m. Next, 366.7 g of a 48% aqueous solution of caustic soda was charged into a reaction vessel equipped with a diffuser, and air was blown from the diffuser at a rate of 1000 cc / min.
While maintaining the reaction temperature at 70 ° C. or lower, the cyanomethylated solution de-cyanated was added dropwise over about 3 hours. After dropping, 3
12 hours while continuing aeration of air at 000 cc / min.
An aging reaction is performed at a reaction temperature of 70 ° C. The color tone of the reaction-terminated liquid was APHA150, and aspartic acid-N, N-
The yield of diacetate tetrasodium salt was 96%, and the amount of impurities was aspartic acid-N, N-diacetate tetrasodium salt, aspartic acid monoacetate sodium salt 3%, IDA
0.3% of sodium salt, 0.3% of sodium salt of NTA,
The fumaric acid sodium salt was 0.2%.

Comparative Example 1 133.1 g of aspartic acid and 130 g of water were charged into a reaction vessel and dispersed. Next, a 37% formalin aqueous solution 16
9 g was added, and 59 g of hydrocyanic acid was further added dropwise over about 1 hour while controlling the reaction temperature to 45 ° C. or lower. After the completion of the dropwise addition, the reaction was further stirred at 40 to 45 ° C. for 3 hours. The amount of cyanide in the ripening solution was 1.8% of the cyanomethylated product.
Met. This aging reaction completed solution was dropped into 366.7 g of a 48% aqueous solution of caustic soda at normal pressure over a period of about 3.5 hours while maintaining the reaction temperature at 70 ° C. After dropping, 70
Further aging reaction was performed at 2 ° C. for 2 hours. Formalin was added in an amount 1.2 times as much as the amount of free cyan contained in the reaction-terminated liquid, and cyanide decomposition treatment was performed at 70 ° C. for 2 hours. This p
Activated carbon (10 g) was added to the reaction completed solution of H13, and after stirring for 30 minutes, the activated carbon was filtered off to obtain an aqueous solution of APHA500 aspartic acid-N, N-diacetate tetrasodium salt. The amount of impurities at this time was aspartic acid-N, N-diacetate 4
Aspartic acid monoacetate sodium salt 4%, IDA sodium salt 3%, NTA sodium salt 3.7%, and fumaric acid sodium salt 0.02% based on the sodium salt.
The activated carbon-treated solution was adjusted to pH 11 with 98% sulfuric acid, and then 10 g of activated carbon was added. After stirring for 30 minutes, the activated carbon was filtered off and decolorized. The APHA of this reprocessing solution was 100. The obtained aqueous solution of aspartic acid-N, N-diacetate tetrasodium salt was dried with a spray dryer to obtain a pale yellow powder. According to the results of content analysis and differential thermal analysis by high performance liquid chromatography, this powder contained 83% of aspartic acid-N, N-diacetate tetrasodium salt and 3% of NTA sodium salt as a monohydrate.

Comparative Example 2 133.1 g of aspartic acid, 166.6 g of a 48% aqueous sodium hydroxide solution and 330.0 g of water were charged into a reaction vessel, and the temperature was raised to 90.degree. 81 g of hydrocyanic acid was added to this mixture,
242.9 g of 37% formalin and 274.8 g of a 48% aqueous sodium hydroxide solution were added dropwise at 100 ° C. over 10 hours. After completion of the dropwise addition, the mixture was stirred at 100 ° C. for 2 hours. After completion of the reaction, 15 g of 10% formalin was added to decompose the remaining hydrocyanic acid. The color tone of this solution was APHA 500 or more, and the yield of aspartic acid-N, N-diacetate tetrasodium salt was 90%. Aspartic acid-N, N-diacetate tetrasodium salt was aspartic acid monoacetate sodium salt 6%, IDA sodium salt 16%, NTA sodium salt 11%, and fumaric acid sodium salt 2%.

Comparative Example 3 In a reaction vessel, 133.1 g of aspartic acid and 130 g of water were charged and dispersed. Next, a 37% formalin aqueous solution 170
g, and 59 g of hydrocyanic acid was further added dropwise over about 1 hour while controlling the reaction temperature to 45 ° C. or lower. After the completion of the dropwise addition, the reaction was further stirred at 40 to 45 ° C. for 3 hours. The amount of cyanide in the ripened solution was 2% of the cyanomethylated product. Next, the ripened solution was placed in 366.7 g of a 48% aqueous sodium hydroxide solution at a reaction temperature of 70 ° C.
It was added dropwise over about 3.5 hours while degassing under reduced pressure to 00 Pa. After completion of the dropwise addition, an aging reaction was carried out at 70 ° C. for 2 hours while degassing under reduced pressure was continued at 40000 Pa. After adding 10 g of 10% hydrogen peroxide solution to the reaction-terminated liquid in which 200 ppm of excess cyanide ion remained, the mixture was stirred for 1 hour to obtain an aqueous solution of aspartic acid-N, N-diacetate tetrasodium salt. The yield of aspartic acid-N, N-diacetate tetrasodium salt was 96%. The amount of impurities was about 3% of sodium aspartate monoacetate, 3% of IDA sodium salt, 3% of NTA sodium salt, and 3% of fumarate sodium salt traces relative to aspartic acid-N, N-diacetate tetrasodium salt. . The color tone of this solution is APHA25
0 and then left at room temperature for 24 hours.
Intensely colored more than 00.

Claims (8)

[Claims] 1. An aspartic acid or aspartic acid monoacetic acid is reacted with a cyanomethylating agent in an aqueous medium to form a cyanomethylated product, and the cyanomethylated product is hydrolyzed in the presence of a base component to give aspartic acid-N, N-diamine. In the method for producing alkali acetates, the amount of cyanate-N, N-diacetate aspartic acid is characterized in that the amount of cyanogen contained in the cyanomethylate is reduced to 1.0% or less during the hydrolysis of the cyanomethylate. Production method. 2. The asparagine according to claim 1, wherein the reaction liquid after the completion of the cyanomethylation ripening reaction and before the hydrolysis reaction is aerated with an inert gas or air and / or degassed under reduced pressure. A method for producing an acid-N, N-diacetate alkali salt. 3. Aeration of an inert gas or air during the hydrolysis of the cyanomethylated product and / or
The method for producing alkali salts of aspartic acid-N, N-diacetate according to claim 1, wherein the degassing is performed under reduced pressure. 4. The method for producing alkaline salts of aspartic acid-N, N-diacetate according to claim 2, wherein the inert gas is at least one selected from nitrogen, helium, neon and argon. 5. The process for producing alkaline salts of aspartic acid-N, N-diacetate according to claim 1, wherein oxygen, oxygen-enriched air or air is passed through the hydrolysis reaction-finished solution to oxidatively decolorize it. . 6. The alkali salts of aspartic acid-N, N-diacetate according to claim 1, wherein hydrogen peroxide is added to the hydrolysis reaction solution in which the concentration of cyanide ions is adjusted to 100 ppm or less to add dehydrogen. Manufacturing method. 7. An acid is added to the hydrolysis reaction completed solution to adjust pH.
2. The method for producing alkali salts of aspartic acid-N, N-diacetate according to claim 1, wherein the color is decolorized by adding activated carbon after setting to 4 to 12. 8. The method according to claim 8, wherein the acid is hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid,
8. The composition according to claim 7, which is at least one selected from glycolic acid, lactic acid, oxalic acid, succinic acid, malic acid, aspartic acid, aspartic acid monoacetic acid, aspartic acid-N, N-diacetic acid, and acidic ion exchange resin. A method for producing an aspartic acid-N, N-diacetate alkali salt.