JPH10259170A - Production of aminopolycarboxylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain an N,N'-alkylenediaminedisuccinic acid at low impurity levels by reaction between an alkylenediamine and a maleic acid alkali salt in an aqueous medium within a specific temperature range. SOLUTION: This aminopolycarboxylic aid is obtained by the following process: a reaction vessel is charged with a maleic acid alkali salt (at 2.0-2.4 (pref. 2.05-2.2) molar times based on the alkylenediamine) together with water with its concentration adjusted to >=40wt.% followed by adding an alkylenediamine such as ethylenediamine, propylenediamine, etc., to the system, the resultant reaction system is heated to 105-120 deg.C (pref. 110-115 deg.C) to conduct a reflux reaction for 6-10h. After ending the reaction, the system is cooled and water is then added to the system to dilute it so that the concentration of the N,N'-alkylenediaminedisuccinic acid alkali salt come to 10-30wt.% (pref. 15-25wt.%); while keeping the resultant system at <=35 deg.C, the system is neutralized with a mineral acid such as sulfuric acid diluted to 20N or lower and adjusted to pH2.0-4.0 to effect crystal deposition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be used in detergents, detergents, pulp bleaching aids, photographic developers, electroless plating agents, fertilizers, etc., and has good biodegradability and therefore has a low environmental load. The present invention relates to a method for producing N, N'-alkylenediamine disuccinic acid as a chelating agent.

[0002]

2. Description of the Related Art As a method of producing N, N'-alkylenediamine disuccinic acid which has been known, a method of reacting aspartic acid with a halogenoalkane such as dibromoethane in the presence of a base (Inorganic Chemistry Vol. 7). (No. 11), p. 2405 (1968)) and a method in which an alkylenediamine and maleic acid or maleic anhydride are heated and reacted in the presence of a strong base (US Pat. No. 3,158,635).
(1964)). Among these methods, the former method using aspartic acid requires a long-time reaction, has a very low reaction yield, and is industrially unsuitable. On the other hand, in the latter method using an alkylenediamine and maleic acid, when the boiling point is close to the boiling point of water, a very long time is required to reach a high reaction result, and the efficiency of the apparatus is poor. there were. On the other hand, when the boiling point is high, favorable results such as decomposition of the target product and side reaction cannot be obtained. Further, there is a problem that when neutralized and crystallized with a strong acid, the target product is easily decomposed and the yield is lowered, and it is difficult to obtain a product of high purity.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for producing N, N'-alkylenediamine disuccinic acid with less impurities and high efficiency. It is in.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object and found that the reaction temperature was 120 ° C.
As described above, when the alkali concentration is too high, a side reaction in which maleic acid is hydrated and malic acid is easily generated is caused, and a target product is decomposed into fumaric acid and an amine to lower the yield. In addition, when the reaction substrate concentration is low and the reaction temperature is 105 ° C. or lower, the reaction time becomes very long,
In contrast to the extremely inefficient result, it has been found that the reaction temperature can be easily maintained by setting the concentration of the maleic acid alkali salt to 40% by weight or more. The present invention has been made based on such findings.

That is, the present invention provides an N, N'-alkylenediamine disuccinate characterized in that the reaction temperature when reacting the alkylenediamine with the alkali maleate in an aqueous medium is in the range of 105 to 120 ° C. This is a method for producing an acid.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The maleic acid alkali salt used in the present invention can be easily obtained by mixing and reacting industrial maleic acid or maleic anhydride with an alkali metal hydroxide or tertiary ammonium in an aqueous medium. it can.

The alkali used in the present invention is preferably an alkali metal hydroxide from the viewpoint of operability and the like. The alkali metal hydroxide may be any one of lithium hydroxide, sodium hydroxide, potassium hydroxide and the like. Although good, sodium hydroxide and potassium hydroxide are preferable from the viewpoint of economy. Further, as the product shape, a flake shape, a granular shape, and an aqueous solution can be used.

As the strong acid used for neutralization, a mineral acid such as sulfuric acid, hydrochloric acid, nitric acid and the like, and an organic acid such as p-toluenesulfonic acid can be used.

[0010] The alkylenediamine used in the present invention includes ethylenediamine or propanediamine.

The production method of the present invention is carried out as follows in order to minimize the production of malic acid as a by-product and to shorten the reaction time. The order of charging may be performed in any order, but is preferably performed as follows from the viewpoint of ease of stirring and operability.

First, a maleic acid alkali salt is adjusted to a concentration of 40% by weight or more and charged into a reaction vessel together with water. Alternatively, maleic acid or maleic anhydride, water and an alkali metal hydroxide are charged so as to be 40% by weight or more at the time of salt formation. If the amount of water is too small, adverse effects such as precipitation of crystals and inability to stir occur, so that sufficient stirring is preferred. The maleic acid alkali salt is used in an amount of 2.0 to 2.4 times, preferably 2.05 to 2.2 times, the moles of the alkylenediamine. When the amount ratio of the maleic acid alkali salt is large, not only is it wasteful, but also the N, N'-
As a result, the purity of the alkylenediamine disuccinic acid decreases and the operability deteriorates. On the other hand, when the ratio is small, the reaction results deteriorate and the purity is lowered.

Finally, an alkylenediamine is added, and 10
The mixture is heated to 5 to 120 ° C, preferably 110 to 115 ° C, and refluxed for 6 to 10 hours. When the reaction temperature is low, a long-time reaction is required, and when the reaction temperature is high, the hydration reaction of maleic acid increases, and the production rate of N, N'-alkylenediamine disuccinic acid decreases. Becomes Therefore, when the preferred reaction temperature is not reached even in the state of the reflux reaction, it is preferable to increase the reaction temperature by adding an alkali metal hydroxide in a range not exceeding 0.5 mol per mol of the maleic acid alkali salt. Good. If too much alkali metal hydroxide is added, maleic acid will be hydrated and the yield will be reduced.

After completion of the reaction, the reaction mixture is cooled and adjusted by adding water so that the concentration of the alkali salt of N, N'-alkylenediaminedisuccinic acid becomes 10 to 30% by weight, preferably 15 to 25% by weight. If the concentration of the alkali salt of N, N'-alkylenediamine disuccinic acid is neutralized to a high concentration, it tends to be supersaturated, and not only rapid crystal precipitation and solidification in the crystallization tank occur, but also the neutralization forms. Inorganic salts are taken into the crystal, which causes a decrease in purity. On the other hand, if it is diluted too much, the amount dissolved in the mother liquor increases, leading to a decrease in the yield.

The solution is kept at 35 ° C. or lower, preferably at 30 ° C.
Neutralized with a mineral acid such as sulfuric acid diluted to 20 N or less while maintaining the pH at 2.0 or less, and adjusting the pH to 2.0 to 4.0, preferably 2.7.
Adjust to 3.5 to precipitate crystals. When a strong acid having a high concentration is used for the neutralization, or when neutralization is performed at a high temperature of 35 ° C. or more, the target substance is decomposed, and the yield is deteriorated.
Further, when the pH is 2 or less, the decomposition of the target substance is likely to occur.

When the crystals are sufficiently precipitated and the pH is stabilized, the crystals are separated from the mother liquor to obtain white crystals of N, N'-alkylenediamine disuccinic acid. In the case of propanediamine disuccinic acid, since the solubility is high, 5 to 10% based on water
Of methanol for neutralization crystallization. In the crystallization operation of the target substance, it is easy to decompose the target substance on the acidic side, especially when the pH is 2 or lower, and the decomposition is remarkable especially at a temperature of 35 ° C. or higher. It is necessary to perform a neutralization operation.

[0017]

Embodiments will be described below with reference to embodiments.

Example 1 A 1000 cc cylindrical stainless steel flask equipped with a stirrer, thermometer, Dimroth condenser, and dropping funnel was charged with 200 g of water, 299.3 g of maleic acid, 430 g of 48% caustic soda, and further 72 g of ethylenediamine. After the addition, the mixture was heated and refluxed at 110 ° C. for 8 hours. The reaction yield at this time was 96%. After completion of the reaction, water was added to dilute the concentration of sodium ethylenediaminedisuccinate to 20%, then cooled to 30 ° C., and adjusted to pH 3.0 with 35% sulfuric acid to precipitate crystals. The crystals were separated from the mother liquor, and 326 g of N, N'-ethylenediaminedisuccinic acid was added.
I got Purity was 95%.

Example 2 500 g of water, 299.3 g of maleic acid and 340 g of 85% potassium hydroxide were charged into a 1000 cc cylindrical stainless steel flask equipped with a stirrer, thermometer, Dimroth condenser, and dropping funnel. 72g
Was added, and the mixture was heated and reacted at 110 ° C. for 8 hours. The reaction yield at this time was 95%. After the reaction is completed, water is added to adjust the concentration of potassium ethylenediaminedisuccinate to 2
After diluting to 5%, cool to 30 ° C and add 40% sulfuric acid to p.
A crystal was precipitated as H3.1. The crystals were separated from the mother liquor to obtain 320 g of N, N'-ethylenediaminedisuccinic acid.

Example 3 A 1000 cc cylindrical stainless steel flask equipped with a stirrer, thermometer, Dimroth condenser, and dropping funnel was charged with 430 g of water, 299.3 g of maleic acid and 430 g of 48% caustic soda, and further 42 g of caustic soda. After the additional addition, 72 g of ethylenediamine was added. This mixture was heated and reacted at 107 ° C. for 10 hours. The reaction yield at this time was 94%. After the completion of the reaction, water was added to dilute the concentration of potassium ethylenediaminedisuccinate to 25%, then cooled to 30 ° C., and pH 3.1 with 40% sulfuric acid.
The crystals were precipitated. The crystals are separated from the mother liquor and N,
319 g of N'-ethylenediaminedisuccinic acid was obtained.

Example 4 195 g of water, 202 g of maleic anhydride, 343.3 g of 48% caustic soda were charged into a 1000 cc cylindrical stainless steel flask equipped with a stirrer, a thermometer, a Dimroth condenser, and a dropping funnel. 74g
Was added. This mixture was refluxed at 110 ° C. for 9 hours. The reaction yield at this time was 95%. After the completion of the reaction, the mixture was cooled to 20 ° C., and N, with water containing 10% of methanol.
Dilute so that the concentration of N'-propanediamine disuccinate sodium salt becomes 25%. After dilution, the pH was adjusted to 3.0 with 60% sulfuric acid to precipitate crystals. The crystals were separated from the mother liquor, and 166 g of N, N'-propanediaminedisuccinic acid was added.
I got

Comparative Example 1 200 g of water, 299.3 g of maleic acid and 430 g of 48% caustic soda were charged into a 1000 cc cylindrical stainless steel flask equipped with a stirrer, thermometer, Dimroth condenser, and dropping funnel, and further 72 g of ethylenediamine. After the addition, the mixture was reacted at a heating temperature of 103 ° C. for 24 hours. At this time, the reaction yield was 82%. The reaction was continued for another 20 hours, and the reaction yield was 89%.

Hereinafter, Comparative Example 2 to 4 were carried out in the same manner as in Comparative Example 1 except that the concentration of the maleic acid alkali salt and the reaction temperature were changed.

[0024] In the table, DA represents alkylenediamine

Comparative Examples 5 to 8 Table 2 shows the results of crystallization of the reaction solution reacted in the same manner as in Example 1 while changing the neutralization temperature, the concentration during neutralization, and the neutralization pH.

[0026] * Using 98% sulfuric acid

[0027]

According to the method of the present invention, N, N'-alkylenediamine disuccinic acid useful as a chelating agent can be efficiently produced with high purity.

Claims (8)

[Claims] 1. A process for producing N, N′-alkylenediamine disuccinic acid, comprising reacting an alkali maleate and an alkylenediamine in an aqueous medium at a reaction temperature of 105 to 120 ° C. 2. The method for producing N, N′-alkylenediamine disuccinic acid according to claim 1, wherein the concentration of the maleic acid alkali salt at the start of the reaction is 40% by weight or more. 3. The process for producing N, N′-alkylenediamine disuccinic acid according to claim 1, wherein the amount of the maleic acid alkali salt used is 2.0 to 2.4 mol per 1 mol of alkylenediamine. Method. 4. An alkali metal hydroxide is added in an amount of 0.5 mol or less based on 1 mol of the maleic acid alkali salt.
The method for producing N, N'-alkylenediamine disuccinic acid according to claim 1, wherein the reaction is performed at a boiling point of 5 to 120 ° C. 5. The N solution according to claim 1, wherein the produced aqueous solution of the alkali salt of N, N'-alkylenediaminedisuccinic acid is diluted to 10 to 30% by weight and then neutralized and crystallized at 35 ° C. or lower. Of N, N'-alkylenediamine disuccinic acid. 6. The method for producing N, N′-alkylenediamine disuccinic acid according to claim 5, wherein the neutralization pH is 2.0 to 4.0. 7. The method for producing N, N′-alkylenediamine disuccinic acid according to claim 5, wherein the acid used for the neutralization crystallization is a strong acid having a concentration of 20 N or less. 8. The method for producing N, N′-alkylenediamine disuccinic acid according to claim 1, wherein the alkylenediamine is ethylenediamine or propanediamine.