JPH09316426A - Aspartic acid derivative and chelate agent containing the same as main component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject new derivative specified in the structure as a free acid, excellent in biodegradability, and suitable as a chelating agent, a surfactant, an emulsifier, etc. SOLUTION: This aspartic acid derivative has a structure of formula I [at least one of R<1> , R<2> is a substituent of formula II (at least one of R<3> , R<4> is a 1-5C alkyl, and the remainder is H), and the remainder is H] as a free acid, e.g. a compound of formula III. The objective derivative is obtained by adding a 3-8C alkylene oxide such as propylene oxide to aspartic acid. The reaction is preferably carried out in the presence of water in an alkaline region in a temperature condition of 20-50 deg.C for approximately 1-10hr.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel amino acid derivative and a chelating agent containing the same as a main component,
Specifically, it has excellent biodegradability, and contains chelating agents, surfactants,
The present invention relates to an amino acid derivative suitable as an emulsifier and the like.

[0002]

2. Description of the Related Art Aminopolycarboxylic acids are used as metal chelating agents in textile / dyeing agents, soap additives, detergent builders, the plating industry, photographic agents or bleaching aids. In such a field, the chelating agent used is often released into the environment as a wastewater component after use, and it is feared that it will eventually be mixed with drinking water from river water and adversely affect health. . Ethylenediaminetetraacetic acid (EDTA), which is a typical aminopolycarboxylic acid, is known to have extremely low biodegradability, and nitrilotriacetic acid (NTA) has been pointed out to have carcinogenicity. There is a need for alternative safe and biodegradable chelating agents.

Examples of conventionally known biodegradable chelating agents include N-hydroxyethyliminodiacetic acid and N, N-bis (hydroxyethyl) glycine, which have excellent chelating ability. It is still inadequate and therefore not widely used.
Natural amino acids are biodegradable aminocarboxylic acids, and among them, several attempts have been known to utilize aspartic acid derivatives, which are aminodicarboxylic acids, as chelating agents.

[0004] For example, Problemy Khimii
In Kompleksonov page 108 (1985), compounds having an oxyethylene group on the nitrogen of aspartic acid are described as metal ion screening agents. However, these compounds are still unsatisfactory in chelating ability. As a method for introducing such an oxyethylene group onto nitrogen, 1) a method for adding ethylene oxide, 2) a method for reacting ethylene chlorohydrin in the presence of a deoxidizing agent are known. The ethylene oxide used has the drawback of being explosive, and the latter has the drawback of producing by-products such as sodium chloride. In JP-A-6-175229, a compound having an oxyalkylene group on the nitrogen of aspartic acid is described as a metal ion shielding agent in a photographic chemical. However, the side chain alkyl group in the oxyalkylene group is not described.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a biodegradable compound having a better chelating ability.

[0006]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that an amino acid derivative obtained by introducing an oxyethylene chain having an alkyl group in the side chain onto the nitrogen atom of an amino acid is obtained. They have found that they exhibit excellent chelating ability, and have completed the present invention. That is, the gist of the present invention is an amino acid derivative whose structure as a free acid is represented by the following general formula (1).

[0007]

Embedded image

(In the formula, at least one of R ¹ and R ² represents a substituent represented by the following formula (2), and the rest represent hydrogen atoms.)

[0009]

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(Wherein at least one of R ³ and R ⁴ represents an alkyl group having 1 to 5 carbon atoms and the rest represent hydrogen atoms), and a chelating agent containing the amino acid derivative as a main component. . Hereinafter, the contents of the present invention will be described in detail.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The amino acid derivative of the present invention is a compound whose structure as a free acid is represented by the following general formula (1).

[0012]

Embedded image

(In the formula, at least one of R ¹ and R ² represents a substituent represented by the following formula (2), and the rest represent hydrogen atoms.)

[0014]

[Chemical 6]

(In the formula, at least one of R ³ and R ⁴ represents an alkyl group having 1 to 5 carbon atoms, and the rest represent hydrogen atoms.) The amino acid derivative of the general formula (1) is a free acid or Exists as its salt. The salt is usually a metal salt or an amine salt. The metal salt is usually an alkali metal salt of sodium, potassium or lithium, but depending on the case, a divalent or higher metal such as an alkaline earth metal salt such as magnesium or calcium, or a transition metal salt such as iron or copper. It may be salted.

In this case, the amino acid derivative of the present invention is present as a chelated complex salt. In the present invention, a compound in which one of R ¹ and R ^{2 in} the general formula (1) shown above is a substituent of the general formula (2) and the other is a hydrogen atom is preferable. Further, it is preferable that one of R ³ and R ^{4 in the above} formula (2) is an alkyl group having 1 to 5 carbon atoms and the other is a hydrogen atom. The alkyl group at this time is preferably a methyl group. Preferred specific examples of these compounds include those having the structures shown below.

[0017]

[Chemical 7]

The compound of the present invention can be produced by adding alkylene oxide having 3 to 8 carbon atoms such as propylene oxide to aspartic acid, and the structure of the compound formed by the molar ratio of alkylene oxide to aspartic acid is Although different, it is usually obtained as a mixture of addition amount 1 (compounds 1 and 2) and addition amount 2 (compounds 3, 4 and 5). These products can be used as a mixture as a chelating agent as they are, but can be isolated by a known method such as recrystallization or column chromatography if necessary.

As a usual synthetic method, aspartic acid is prepared without solvent or by dissolving it in a solvent, introducing a predetermined amount of alkylene oxide therein, and then stirring the mixture at room temperature or under heating to easily obtain the desired product. Is obtained. The aspartic acid to be used may be a racemic body or an optically active body, but the L body is preferable from the viewpoint of biocompatibility and environmental compatibility. It is also possible to use industrial crude products containing impurities such as maleic acid and fumaric acid.

The reaction is usually carried out using a solvent. The solvent may be one that solubilizes all or part of aspartic acid, and water, protic solvents such as alcohols, dimethyl sulfoxide, aprotic polar solvents such as dimethylformamide, etc. can be presented, but preferably Water is used. The pH of the reaction is not particularly limited,
In order to increase the solubility of aspartic acid, it is usually performed in the alkaline region. A base is used to make it alkaline. In this case, the base used is an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, an alkaline earth metal hydroxide such as calcium hydroxide or magnesium hydroxide, or ammonia. , Amines such as triethylamine and pyridine. Although the amount of the base used can be set arbitrarily, it is usually 0.
It is carried out in the range of 5 to 2 molar times.

The amount of alkylene oxide used can be adjusted according to the desired amount of addition and the reduction due to side reactions, but it is usually from 1 mol times to 10 times the amount of aspartic acid.
A molar ratio, preferably 1 to 4 mol times, is used. The reaction temperature is 0 ° C to 200 ° C, preferably 20 ° C to 50 ° C.
C., and can be easily carried out within a temperature range where the alkylene oxide can normally maintain a liquid phase. The reaction time is 1 hour to 100 hours, usually 1 hour to 10 hours.

After the reaction, the low-boiling substance is usually distilled off as it is, whereby the product is obtained as a solid in the form of a carboxylic acid salt with the base used. When a protic solvent such as water is used as the solvent, a substance obtained by reacting the solvent with the alkylene oxide is by-produced, which is also usually distilled off under reduced pressure. Alternatively, the product may be neutralized to near the isoelectric point of the product and then isolated in the form of a free carboxylic acid. Examples of the acid used in this case are usually mineral acids such as hydrochloric acid, sulfuric acid and nitric acid.

A so-called reprecipitation method is also effective in which a product dissolved in a soluble solvent such as water or alcohol is dropped into a solvent having a low solubility such as acetone or acetonitrile for crystallization. The amino acid derivative of the present invention is useful as a chelating agent and is used for detergent builders, fiber processing, dyeing, photographic development, bleaching agent stabilization, plating and the like.

[0024]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. [Example 1] (Synthesis of propylene oxide adduct of aspartic acid) 13.31 g (0.1 mol) of L-aspartic acid was added to 20 ml of water and 10 ml of methanol, and with 8.33 g (0.2 mol) of 96% sodium hydroxide. Neutralize. 14 ml (0.2 mol) of propylene oxide is added thereto, and the mixture is stirred at room temperature. As the reaction progresses, heat is generated and the reaction liquid changes from a heterogeneous system to a homogeneous system. After reacting at a maximum temperature of 34 ° C. for 4 hours, the solvent and low-boiling substances were distilled off under reduced pressure.
7.54 g of crystals were obtained. Weight increase, elemental analysis, and various spectroscopic analyzes revealed that it was an L-aspartic acid propylene oxide adduct disodium salt (mixture of compounds 1 and 3) with an average addition amount of 1.6.

Elemental analysis C: 35.72 wt%, H:
5.43 wt%, N: 4.70 wt% ¹ H NMR 1.1 ppm (CH ₃ , m, 4.8)
H), 2.4-2.6 ppm (CH ₂ , m, 3.2
H), 2.6-2.8 ppm (CH ₂ , m, 2H),
3.5-3.7 ppm (CH, m, 1.6H), 3.8
-3.9 ppm (CH, m, 1H) IR 3300 cm ^-1 (OH expansion and contraction), 1600 (C = O)
Expansion and contraction)

Example 2 An experiment was conducted in the same manner as in Example 1 except that the amount of propylene oxide used was 28 ml (0.4 mol), and the disodium L-aspartic acid propylene oxide adduct having an average addition amount of 2 was added. Salt (compound 3)
30.3 g of white crystals of Elemental analysis C: 40.82 wt%, H: 6.82 wt
%, N: 3.92 wt% ¹ H NMR 1.1 ppm (CH ₃ , m, 6H),
2.4-2.6 ppm (CH ₂ , m, 4H), 2.6-
2.8 ppm (CH ₂ , m, 2H), 3.5-3.7p
pm (CH, m, 2H), 3.8-3.9 ppm (C
H, m, 1H) IR 3300 cm ^-1 (OH expansion and contraction), 1600 (C = O
Expansion and contraction)

Comparative Example 1 (Synthesis of Aspartic Acid Ethylene Oxide Adduct) 2.66 g (20 mM) of L-aspartic acid was added to 10 m of water.
1.67 g of 96% sodium hydroxide (40 m
Neutralize with M). The reaction solution was heated to 40 ° C, and while stirring, 3.86 g (48 mM) of 3 of ethylene chlorohydrin was added.
0% methanol solution and sodium hydroxide 2.0 g (48
A 20% aqueous solution (mM) is simultaneously added dropwise over 4 hours. When the reaction was further performed for 1 hour, the conversion rate was 100%. 40 ml of water was added thereto, and concentrated hydrochloric acid was further added until the pH reached 2.2, and the obtained crystals were removed. To the filtrate was further added 10 ml of methanol to remove the regenerated crystals, and the filtrate was concentrated to give an average addition amount of 1.5.
As a result, 6.07 g of an ethylene oxide adduct of aspartic acid was obtained as an oily substance.

[Chelate Test Example] For each of the compounds obtained in the above Examples and Comparative Examples, EDTA and L-aspartic acid, the chelating ability of copper ion was measured by the following method. About 0.3g of sample is 40m distilled water
Dissolve in 1 and add sodium hydroxide if it is not in sodium salt form to make sodium salt form and adjust pH to about 11. Here, 5m of 0.2 mol sodium carbonate aqueous solution
Add l. A pH meter and a thermometer were set to this solution, a 0.25 mol copper acetate aqueous solution was added dropwise with a buret, the amount of addition until reaching the cloud point was determined, and the chelating ability was calculated by the following formula. The results are shown in Table 1.

[0029]

[Equation 1]

[0030]

[Table 1]

Claims (4)

[Claims] 1. An amino acid derivative having a structure as a free acid represented by the following general formula (1). Embedded image (In the formula, at least one of R ¹ and R ² represents a substituent represented by the following formula (2), and the rest represent hydrogen atoms.) (In the formula, at least one of R ³ and R ⁴ has 1 to 1 carbon atoms.
5 represents an alkyl group, and the rest represent hydrogen atoms. ) 2. R ³ and R ⁴ in the general formula (2) shown above.
The amino acid derivative according to claim 1, wherein one is an alkyl group having 1 to 5 carbon atoms and the other is a hydrogen atom. 3. R ³ and R ⁴ in the general formula (2) shown above.
The amino acid derivative according to claim 1, wherein one is a methyl group and the other is a hydrogen atom. 4. A chelating agent containing an amino acid derivative represented by the above general formula (1) as a main component.