JP2001261622A - Aminopolycarboxylate, method for producing the same and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable chelating agent having higher chelating ability and stability than those of a conventionally proposed chelating agent. SOLUTION: This biodegradable chelating agent comprises an alkali metal salt of an aminopolycarboxylic acid represented by the following general formula (1) (wherein M1, M2, M3 and M4 denote each independently hydrogen atom or an alkali metal, with the proviso that all of the M1, M2, M3 and M4 are not hydrogen atoms) as an active ingredient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biodegradable aminopolycarboxylic acid useful as a chelating agent.

[0002]

2. Description of the Related Art Conventionally, as a chelating agent, an electrolyte polymer such as polyacrylic acid or polymaleic acid, an aminocarboxylate such as ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid, or a polyphosphate such as sodium tripolyphosphate has been used. It has been. However, all of these conventional chelating agents have low biodegradability, and in recent years, an adverse effect on the environment has been concerned. For this reason, various chelating agents having biodegradability have been proposed.

For example, JP-A-5-72695 discloses N, N'-alkylenediaminedisuccinic acid,
JP-A-165271 discloses 2-hydroxy-1,3-propanediaminepolycarboxylic acid, JP-A-9-87675 discloses an unsaturated aminocarboxylic acid, JP-A-9-1245.
No. 67, 2,2'-dimethyliminodiacetic acid derivative, JP-A-8-188549, glycerin derivative, JP-A-8-92197, 2-sulfoethylaminocarboxylic acid, JP-A-7-89913 Japanese Patent Application Publication No. JP-A-2005-26464 discloses an aspartic acid derivative. Also, Japanese Patent Application Laid-Open
-64260 discloses diethylenetriamine-N,
N "-dimalonic acid or its iron (III) complex salt is disclosed.

[0004]

However, these chelating agents having a conventionally proposed biodegradability are:
There are problems such as low chelation ability and low stability,
It was not industrially satisfactory.

For example, diethylenetriamine-N, N "-dimalonic acid described in JP-A-7-64260 has extremely low stability and cannot be isolated with high purity, and is therefore used industrially. The publication also describes the iron (III) complex salt, but since this compound is an iron complex salt, it has no ability to chelate calcium ions and the like.
This publication only describes the use of an iron complex salt as a bleaching agent, but does not disclose any other salts or examples of their use as chelating agents.

The publication also discloses that diethylenetriamine-
A method for producing N, N "-dimalonic acid is described in Bull.
hem. Soc. Japan. , 46, 844 (197
It is described that the compound can be synthesized according to the method for producing ethylenediamine-N, N'-dimalonic acid described in 3). Therefore, diethylenetriamine-N,
As an intermediate during the production of the iron (III) complex salt of N "-dimalonic acid, diethylenetriamine-N, N" -dimalonic acid is used.
Since N, N "-dimalonic acid is unstable and cannot be taken out with high purity, it has not been industrially satisfactory.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a biodegradable chelating agent having higher chelating ability and stability than conventionally proposed chelating agents. .

[0008]

The present inventors have conducted intensive studies on aminopolycarboxylic acid-based chelating agents. As a result, the aminopolycarboxylic acid salt represented by the following general formula (1) having high chelating ability was converted to malonic acid. The present inventors have found a novel fact that they can be easily derived from esters and diethylenetriamine and are stable, and have completed the present invention.

[0009]

Embedded image

(Wherein M1, M2, M3 and M4 each independently represent a hydrogen atom or a cation.
M2, M3 and M4 are not all hydrogen atoms. That is, the present invention provides an aminopolycarboxylic acid represented by the above general formula (1), which comprises reacting an alkali metal salt of aminopolycarboxylic acid represented by the above general formula (1), diethylenetriamine, and a malonic ester derivative. A biodegradable chelating agent comprising a method for producing a carboxylic acid and an alkali metal salt of an aminopolycarboxylic acid represented by the general formula (1) as an active ingredient.

Hereinafter, the present invention will be described in more detail.

The aminopolycarboxylate of the present invention is a compound represented by the above general formula (1).

In the general formula (1), M1, M2,
M3 and M4 each independently represent a hydrogen atom or a cation. What is important here is that M1, M2, M3 and M4 are not all hydrogen atoms. If all are hydrogen atoms, the stability is significantly reduced. The cation is preferably an alkali metal ion, but may be an ammonium ion.

The alkali metal salts of aminopolycarboxylic acids according to the invention are isolated in crystalline form. These crystals are stable and easy to handle industrially.

In the method of the present invention, the above general formula (1)
An alkali metal salt of an aminopolycarboxylic acid represented by
Obtained from one molecule of diethylenetriamine and two molecules of malonic ester derivatives. As the malonic ester derivative, a derivative having a leaving group in the methylene portion of malonic acid can be used, and a halogenated malonic ester is preferred. Halogenated malonic esters can be easily derived from malonic esters. Although the method for producing the halogenated malonic ester is not particularly limited, for example, it is easiest to halogenate the malonic ester. At the time of halogenation, any of fluorine, chlorine, bromine and iodine may be used, but chlorine and bromine are preferably used from the viewpoint of easy handling.

In the method of the present invention, the reaction between the malonic ester derivative and diethylenetriamine may be performed by heating, or may be performed at a low temperature such that the reaction solution does not solidify, or at room temperature.

Although the amount of the malonic ester derivative used in the method of the present invention is not particularly limited, it is preferably added in an amount of 2 to 4 mol per mol of diethylenetriamine. If less than 2 moles are added, a reaction intermediate in which one molecule of malonic ester is added to diethylenetriamine will be produced and mixed into the reaction product. Addition of 4 moles or more is industrially disadvantageous. It is.

In the method of the present invention, the method of addition is not particularly limited, but the malonic ester derivative may be added dropwise to an alkaline aqueous solution of diethylenetriamine, or the diethylenetriamine and malonic ester derivative may be simultaneously added to an alkaline aqueous solution. Good.

In the method of the present invention, the reaction between the malonic ester derivative and diethylenetriamine is carried out in an aqueous alkaline solution. The pH of the reaction solution may be 7 or more,
Preferably, the reaction is carried out at a pH between 8 and 14.
Examples of the alkali include, but are not particularly limited to, hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, carbonates such as sodium carbonate, potassium carbonate, and lithium carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate. Oxides such as bicarbonate, sodium oxide, potassium oxide, lithium oxide, such as lithium bicarbonate,
Metals such as metallic sodium, metallic potassium and metallic lithium can be used without any problem as long as they are soluble in water or react with water and show alkalinity. The amount of the alkali to be added is preferably at least 1 mol, more preferably at least 2 to 4 mol, per mol of the malonic ester derivative in order to capture the halogen generated during the reaction and to hydrolyze the ester.

In the method of the present invention, the resulting alkali metal salt of aminopolycarboxylic acid can be easily purified by crystallization or recrystallization. In the case of crystallization, a poor solvent such as an alcohol is added to an aqueous solution of an alkali metal salt of aminopolycarboxylic acid. In the case of recrystallization, the recrystallization is performed in a solution in which a poor solvent such as alcohol compatible with water and water are mixed. In these cases, as long as they are compatible with water, not only alcohols can be used, but the cheapest alcohols are industrially advantageous. Examples of alcohols include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, cyclohexanol, ethylene glycol, glycerin, etc., but methanol, ethanol,
Propanol is preferred.

In the method of the present invention, the obtained alkali metal salt of aminopolycarboxylic acid can be used as a chelating agent. As the chelating agent, only an alkali metal salt of aminopolycarboxylic acid may be used, or may be used in combination with another agent.

The chelating agent of the present invention can chelate various metal ions. Examples of the metal ion include an alkali metal (eg, lithium, sodium, potassium, etc.) ion and an alkaline earth metal (eg, calcium,
Ions of magnesium, barium, etc., metals (eg, A
1, Cr, Mo, W, Mn, Ru, Os, Co, Rh,
Ir, Fe, Ni, Pd, Pt, Cu, Ag, Au, Z
n, Cd, Hg, etc.).

The chelating agent can chelate metals in water, and can be used as a fiber / dyeing agent, photographic agent, paper pulp bleaching agent, soap, detergent builder, scale inhibitor, complexing agent for metal surface treatment. And can be widely used as a metal ion masking agent for analysis and the like. This chelating agent is biodegradable, and can reduce the load on a conventional chelating agent such as ethylenediaminetetraacetic acid that has been applied to the environment. The specific method of use of the chelating agent of the present invention and the amount of use vary depending on each application, so it cannot be said unconditionally, but in principle, it does not differ significantly from the general use in each application. . However, the chelating agent of the present invention can be expected to use cases that have never existed before because of its excellent functions and effects,
Needless to say, the amount of use can be reduced to achieve the same effect.

[0024]

According to the present invention, an alkali of aminopolycarboxylic acid having biodegradability enough to cause no environmental problems and having extremely high chelating ability as compared with conventionally proposed biodegradable chelating agents. A metal salt can be provided.

[0025]

EXAMPLES Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited thereto.

Production Example 1 16.0 g of diethyl malonate was added to 27.3 g of carbon tetrachloride, and 16.4 g of bromine was added dropwise at room temperature with stirring. After completion of the dropwise addition, the mixture was heated to 80 ° C. and refluxed for 1 hour to remove hydrogen bromide generated in the reaction. The obtained reaction solution was washed with a 5% aqueous solution of sodium carbonate, and after removing carbon tetrachloride, 19.1 g (yield: 8) was obtained by performing a distillation operation.
(0.0%).

Example 1 5.2 g of diethylenetriamine, sodium hydroxide 1
In a glass eggplant-shaped flask containing 8.0 g and 70.5 g of water, 35.9 g of diethyl bromide malonate was added dropwise with stirring and cooling with ice. The pH at the end of the dropwise addition was 13.3. Dilute hydrochloric acid was added to the reaction solution to adjust the pH to 4.0.
Crystals of the sodium salt precipitated. Sodium hydroxide was added to the crystals and dissolved in water, and then methanol was added, whereby white tetrasodium salt crystals were precipitated at a yield of 28.7%.

¹ H-NMR of sodium salt of aminopolycarboxylic acid represented by the formula (1): CH ₂ (δ 2.40-2.60 ppm, d
d) CHCOO (δ 3.48 ppm, s) ¹³ C-NMR: CH ₂ (δ 50.2 ppm) CH ₂ (δ 52.2 ppm) CH (δ 74.4 ppm) COO (δ 181.6 ppm) Tetrasodium salt of this aminopolycarboxylic acid Was stored at 50 ° C. for 2 weeks and a stability test was carried out. As a result, no decrease in purity was observed.

Next, an equivalent amount of a 1 mmol / l aqueous solution of calcium chloride was added to a 1 mmol / l aqueous solution of the aminopolycarboxylic acid sodium salt. The calcium ion concentration at pH 10.0 was measured with a calcium ion electrode,
The stability constant pKCa ²⁺ of calcium ions was determined. 2
PKCa ^{2+ at} 5 ° C. was 4.4.

Further, the aminopolycarboxylic acid sodium salt was adjusted to a concentration of 30 mg / l, and 100 mg /
1 l of activated sludge was added and a biodegradability test was performed at 25 ° C. for 2 weeks. As a result, the aminopolycarboxylic acid is 7
0% was decomposed.

Comparative Example 1 The crystals of the disodium salt obtained in Example 1 were dissolved again in water and acid-precipitated with dilute hydrochloric acid to obtain an aminopolycarboxylic acid.

When the aminopolycarboxylic acid was stored at 50 ° C., decarboxylation occurred one day later to cause decomposition, and no aminopolycarboxylic acid remained.

Comparative Example 2 An equal amount of a 1 mmol / l calcium chloride aqueous solution was added to a 1 mmol / l aqueous solution of a commercially available biodegradable chelating agent (trisodium N, N'-ethylenediaminedisuccinate). The calcium ion concentration at pH 10 was measured with a calcium ion electrode, and the stability constant pKCa ²⁺ of calcium ions was determined. PKCa ^{2+ at} 25 ° C.
It was 8.

Comparative Example 3 An equal amount of a 1 mmol / l aqueous solution of calcium chloride was added to a 1 mmol / l aqueous solution of a commercially available chelating agent (tetrasodium ethylenediaminetetraacetate). The calcium ion concentration at pH 10 is measured with a calcium ion electrode,
The stability constant pKCa ²⁺ of calcium ions was determined. 2
PKCa ^{2+ at} 5 ° C. was 6.6. When a biodegradability test of this chelating agent was performed under the same conditions as in Example 1, almost no decomposition was observed.

Comparative Example 4 The sodium salt of aminocarboxylic acid obtained in Example 1 was dissolved in water, and 1 mmol / l of iron (III) nitrate was added thereto.
The iron (III) complex salt of aminocarboxylic acid was prepared. An equal amount of a 1 mmol / l calcium chloride aqueous solution was added to this aqueous solution. The calcium ion concentration at pH 10 was measured with a calcium ion electrode, and the chelation stability constant pKCa ²⁺ of calcium ion was determined, but no chelation stability constant was shown.

[0036]

The present invention is to provide a novel biodegradable chelating agent having excellent stability and high chelating ability, which is extremely significant.

Claims (7)

[Claims] 1. An alkali metal salt of an aminopolycarboxylic acid represented by the following general formula (1). Embedded image (Wherein, M1, M2, M3 and M4 each independently represent a hydrogen atom or an alkali metal; provided that M1, M2, M
3 and M4 are not all hydrogen atoms. ) 2. The method for producing an alkali metal salt of aminopolycarboxylic acid according to claim 1, wherein diethylenetriamine is reacted with a malonic ester derivative. 3. The method according to claim 2, wherein the malonic ester derivative is a halogenated malonic ester. 4. The method according to claim 3, wherein the malonic ester derivative is reacted with diethylenetriamine in an aqueous alkali solution. 5. A method for producing an alkali metal salt of aminopolycarboxylic acid, comprising crystallization by adding an alcohol to the aqueous solution of aminopolycarboxylate according to claim 1. 6. A method for producing an alkali metal salt of aminopolycarboxylic acid, comprising recrystallizing the alkali metal salt of aminopolycarboxylic acid according to claim 1 in a mixed solvent of water and alcohol. 7. A biodegradable chelating agent comprising the alkali metal salt of aminopolycarboxylic acid according to claim 1 as an active ingredient.