JPH11130741A - S,s-ethylenediamine-n,n'-disuccinate alkali salt and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject compound with good storage stability, having favorable biodegradability, slight in environmental loading, and useful as a chelating compound usable in bleaching agents and fertilizers, by limiting the quantities of specific impurities existing as reaction byproducts therein to a specified level or lower. SOLUTION: This compound is such one that the contents of (A) a lactam compound of formula I (M is ammonium ion or an alkali metal ion) and (B) ethylenediaminemonosuccinic acid of formula II are limited to <=7 wt.%, respectively, and is obtained, pref. by reaction between iron oxide and an S,S- ethylenediamine-N,N'-disuccinic acid alkali salt in the presence of powder such as of iron, a thready metal, and/or a compound such as ascorbic acid, as reducing agent; alternatively, by washing treatment with a hydrous lower alcohol such as methyl alcohol of a concentrate or dried product of an aqueous solution of an iron S,S-ethylenediamine-N,N'-disuccinate alkali salt containing >7 wt.% of the impurities (A) and (B), respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a chelate compound which can be used in photographic bleaching agents, fertilizers and the like.
The present invention relates to an alkali salt of S, S-ethylenediamine-N, N'-disuccinate iron which has good biodegradability and has a low environmental load, and a method for producing the same.

[0002]

2. Description of the Related Art The present inventors have disclosed in Japanese Patent Application Laid-Open No. 8-34764, a ferric ammonium salt of S, S-ethylenediamine-N, N'-disuccinate, which is a compound useful for photographic bleaching, has high biodegradability. That was shown. However, in the disclosed method for producing a compound, it is necessary to obtain a concentrated solution having a high viscosity and a high slurry concentration due to the extremely high solubility of the target compound, and a production method having higher productivity is desired as an industrial production method. Was. In addition, in the acquisition method by concentrating to dryness or drying with a continuous hot air transport type, although the yield is improved, the obtained powder has poor stability over time, and quality problems such as deterioration of coloring and dissolution are recognized. was there.

[0003] In the production method using iron oxide, unlike the case where an inorganic salt such as iron sulfate is used, as long as the raw material is not decomposed, the reaction solution is evaporated to dryness as it is to obtain a relatively high-purity target. It was expected that things could be obtained. However, in the case of ethylenediamine-N, N'-disuccinic acid as a meso-racemic mixture, the resulting product not only has an extremely high hygroscopicity but also has an insufficient purity. Was. Further, S, S-ethylenediamine-N,
In the case of N'-disuccinic acid, the solid obtained is not only poor in stability but also low in purity due to coloring over time and generation of insolubles. The mass balance of diamine-N, N'-disuccinic acid was not significantly consistent.

[0004]

DISCLOSURE OF THE INVENTION An object of the present invention is to overcome the above-mentioned problems and to provide an alkali salt of S, S-ethylenediamine-N, N'-disuccinate having high storage stability and a method for producing the same in a high yield. Is to provide.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and have found that the chelating ability is significantly lower than others. However, the presence of impurities that are difficult to detect even from various analysis such as mass spectrum and NMR shows that S, S-ethylenediamine-N,
It was found to be a lactam ring-forming product of N'-disuccinic acid. Deterioration in coloration and stability over time is caused by the presence of compounds of the following general formula (1) and compounds of the following general formula (2) as reaction by-products, and these compounds have low iron chelate stability.
It is the result of releasing the chelated iron over time, and it was found that it is important to reduce the amount of these reaction by-products.

[0006] [M is an ammonium ion or an alkali metal ion]

[0007] [M is an ammonium ion or an alkali metal ion]

Furthermore, it has been found that even if these compounds are contained, no serious problem will occur in the stability over time if the content is 7% by weight or less. In addition, the reaction temperature, time and pH are appropriately controlled, and the generation of these impurities is suppressed by adding a reducing substance. Among the generated impurities, while the lactam compound is easily dissolved in lower alcohols, , S-Ethylenediamine-N, N'-iron disuccinate does not dissolve, so that only impurities can be eluted. According to the continuous hot air transport drying method, S,
The inventors have found that the decomposition reaction of S-ethylenediamine-N, N'-disuccinic acid is minimized and the oxidation reaction of ferrous iron easily proceeds simultaneously with drying, and the present invention has been completed.

That is, the first invention of the present invention is characterized in that the lactam compound represented by the following general formula (1) and the ethylenediamine monosuccinic acid represented by the following general formula (2) are each 7% by weight or less. The gist of the present invention is to provide an alkali metal salt of S, S-ethylenediamine-N, N'-disuccinate.

[0010] [M is an ammonium ion or an alkali metal ion]

[0011] [M is an ammonium ion or an alkali metal ion]

The second invention of the present invention relates to the above general formula (1)
Alternatively, after removing the water content of the aqueous solution of the alkali salt of S, S-ethylenediamine-N, N′-disuccinic acid containing more than 7% by weight of the compound represented by the general formula (2), methyl alcohol, ethyl alcohol, The S, S-ethylenediamine according to the first aspect of the present invention, wherein the S, S-ethylenediamine is dispersed or washed in at least one hydrated lower alcohol selected from the group consisting of propyl alcohol, n-propyl alcohol, isobutyl alcohol and tertiary butyl alcohol. This is a method for producing an alkali salt of N, N'-disuccinic acid.

[0013] The third invention of the present invention relates to iron oxide and S, S-
Ethylenediamine-N, N'-disuccinic acid alkaline salt may be at least one powder or thread-shaped metal selected from the group consisting of iron, aluminum, magnesium and zinc, and / or ascorbic acid, isoascorbic acid, S, S-ethylenediamine-N, according to the first invention, characterized in that at least one compound selected from the group consisting of formic acid and oxalic acid is added and reacted.
This is a method for producing an alkali metal salt of N'-disuccinate.

[0014] The fourth invention of the present invention relates to the use of iron oxide B
Hematite with ET value of 10 (m ² / g) or more, BET value of 5
(M ² / g) or more magnetite and BET value 85 (m
² / g) The method for producing an alkali metal salt of S, S-ethylenediamine-N, N'-disuccinate according to the third aspect of the present invention, which is at least one selected from the group consisting of goethite of at least ² / g).

According to a fifth aspect of the present invention, there is provided the S, S-type of the first aspect, wherein the oxidation and drying of ferrous iron to ferric iron are simultaneously performed by a continuous hot-air conveying dryer. This is a method for producing an ethylenediamine-N, N'-disuccinate iron alkali salt.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

Alkali S, S-ethylenediamine-N, N'-disuccinate is a compound which is stable at room temperature and has a very high solubility in water of 60 g / 50 g H ₂ O or more. Moreover, the raw materials S,
S-ethylenediamine-N, N'-disuccinic acid is an unstable compound that undergoes decomposition by a lactam ring formation reaction or an amine elimination reaction in an acidic solution. In addition, it is a strongly acidic substance having a pH of about 2 in an aqueous solution. Therefore, in the presence of water even at room temperature, cyclization proceeds gradually without adding an acidic substance, and the cyclized product and amine are heated. It has the property of accelerating the production of fumaric acid and ethylenediamine monosuccinic acid by the elimination reaction of. On the other hand, this S, S
-S, S-Ethylenediamine-N, N'- by chelating iron with ethylenediamine-N, N'-disuccinic acid
Iron disuccinate alkali salt is a weakly acidic substance having a pH of about 5, and is a stable compound as compared with S, S-ethylenediamine-N, N'-disuccinic acid, and its aqueous solution can be stably stored. However, the reaction of chelating iron results in extremely low reactivity of iron oxide under basic conditions, and also generates a large amount of iron hydroxide and iron ammine complex. Further, S, S-ethylenediamine-N,
When trying to obtain an alkali salt of iron N'-disuccinate, excess alkali is not preferred because it inhibits hygroscopicity and product stability. For this reason, a heating reaction occurs in a weakly acidic region having a pH of 3 to 6, which causes the generation of these by-products. In addition, these by-products due to the elimination reaction of cyclized products and amines have weaker chelating power than S, S-ethylenediamine-N, N'-disuccinic acid, and thus change in pH and change in liquid composition due to additives. The iron ions are liberated even after the impact caused by the aging, and as a result, a water-insoluble iron hydrate is formed and the aqueous solution becomes turbid. However, this turbidity could be prevented to such an extent that there was no problem in use by reducing the amount of these by-products to 7% by weight or less. Further, by the following measures, these by-products could be produced in a composition of 7% by weight or less.

The formation of decomposed products and cyclized products depends on the temperature, reaction time, and pH during the chelation reaction in which iron or iron oxide is reacted with S, S-ethylenediamine-N, N'-disuccinic acid. By adjusting the conditions to suitable conditions and adding a stabilizer, a product having a small amount of by-products can be obtained. More specifically, although it depends on the particle size, quality, and type of the iron oxide used, when hematite is used, a BET value of 10 (m
² / g), preferably 15 (m ² / g) or more, and in the case of magnetite, 5 (m ² / g)
/ g) or more, preferably better to use one having a specific surface area of 6 (m ² / g) or more, goethite, 85 (m ²
/ g) or more, more preferably 95 (m ² / g) or more. Further, in terms of the type of iron oxide, magnetite is most preferred, followed by hematite. Here, the BET value is a measured value of the specific surface area by low-temperature N ₂ gas adsorption. The reaction temperature is 65-100
C., preferably 70 to 95 ° C., and the reaction time is 5 to 240 minutes, preferably 15 to 180 minutes.

Furthermore, the addition of a reducing substance during the chelation reaction can suppress the formation of cyclized products. Specifically, as a reducing substance, a metal powder such as iron powder, zinc powder, magnesium powder, and aluminum powder, or an inorganic reducing substance in the form of a metal wire or ribbon, and an organic reducing substance such as ascorbic acid, isoascorbic acid, and oxalic acid. Although a conductive substance can be used, it is preferable to use iron from the viewpoint of suppressing contamination of the product with impurities. The amount of these additives is 0.1 to 20 mol%, more preferably 1 to 20 mol%, based on S, S-ethylenediamine-N, N'-disuccinic acid.
It is preferable to add about 10 mol%. Reaction solution pH at this time
Is performed in the range of 3 to 7, preferably 3.5 to 5.5.

In the reaction solution obtained by dissolving and chelating iron oxide as described above, a small amount of ferrous iron is present when hematite or goethite is used as iron oxide, and when magnetite is used, Contains several to ten-odd percent of ferrous iron. Oxidation of these ferrous irons to ferric iron can be carried out with molecular oxygen, but when the target composition is to be obtained in powder form, molecular oxygen is added to a reaction solution as conventionally performed. It is not necessary to dry after introduction and oxidation reaction. The use of the continuous hot air transport type dryer not only effectively oxidizes the air introduced during drying but also shortens the processing time, so that S, S-ethylenediamine which has conventionally occurred during air blowing is used. Due to the effect of suppressing the decomposition of N, N'-disuccinic acid, a powder of the target composition can be obtained efficiently. Examples of the continuous hot air transfer dryer include a spray dryer and a continuous granulation dryer. The temperature of the hot air used can be in the range of 70 ° C to 200 ° C.

The S, S-ethylenediamine-N, N'-iron disuccinate alkali salt reaction solution having a composition such that the by-products exceed 7% is made to have a low water content or a dry condition, and then washed with a water-containing lower alcohol. By processing
S, S-ethylenediamine-N of the target composition efficiently,
An N'-disuccinic acid alkali salt can be obtained. Examples of the lower alcohol include lower alcohols having 1 to 4 carbon atoms, specifically, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, isobutyl alcohol, tertiary butyl alcohol, and the like.

Specifically, an alkali reaction solution of S, S-ethylenediamine-N, N'-iron disuccinate containing a large amount of by-products is concentrated under reduced pressure to evaporate water until it becomes 60% or less of solid components. Let it. Then, the water concentration is 3 to 35.
%, Preferably 5 to 20%, of anhydrous or hydrated lower alcohol so as to obtain a hydrated lower alcohol to disperse the crystals. This can be easily filtered and separated to obtain an alkali iron salt of S, S-ethylenediamine-N, N'-disuccinate having a composition such that the by-product exceeds 7%.

As another treatment method, after drying with a continuous hot air transport type drier such as spray drying, the dried product is hydrated with 3 to 35% of lower alcohol, preferably 5 to 35%.
After dispersing in 20% hydrated lower alcohol, it is separated by filtration or filled in a Nutsche or the like and washed by rinsing with hydrated alcohol, whereby S, S-ethylenediamine-containing 7% or less of the by-product is easily obtained. N, N'-iron disuccinate alkali salt can be obtained.

[0024]

Embodiments will be described below with reference to embodiments.

The analysis methods for the iron yield, iron content and chelate component are as follows.

[0026]

Analysis of iron content: After all the dissolved iron is converted to ferric iron, the resultant is reacted with potassium iodide, and titrated with sodium thiosulfate using starch as an indicator.

Analysis method of chelate component: Iron complex is removed by adding an aqueous solution of sodium hydroxide to remove iron, and then dissolved in a solution containing copper to form a copper complex, followed by liquid chromatography (column: ODS-2). 254 nm, eluate;
(Buffer containing copper, analysis temperature: 40 ° C).

Example 1 A reactor equipped with a stirrer and a thermometer was charged with 146 g of S, S-ethylenediamine-N, N'-disuccinic acid, 300 g of water, and 21 g of 98% sodium hydroxide, and stirred and mixed at room temperature. To this, 37.7 g of magnetite having a BET value of 6.5 (m ² / g) and 1.4 g of iron powder were added.
The mixture was heated for 2 hours. As a by-product of this reaction solution, the lactam cyclized product was 2.7%, and the deamined ethylenediamine monosuccinic acid was 2%. The obtained reaction solution was filtered to remove insolubles, and then S, S-ethylenediamine-
The pH was adjusted to 5 with N, N'-disuccinic acid. This adjusted solution was treated with a spray-drying dryer, and the lactam ring content was 2.5% and the ethylenediamine monosuccinic acid content was 2%.
The S, S-ethylenediamine-N, N′-iron disuccinate sodium salt composition having the following composition was obtained with an iron yield of 98%.

Examples 2 to 10 The reaction results obtained by changing the stabilizer in the same manner as in Example 1 are shown in Table 1.
Shown in

[0031]

Comparative Example 1 The reaction was carried out under the same conditions as in Example 1 without adding a stabilizer, and post-treatment was carried out. Table 1 shows the results.

Example 11 The pH-adjusted solution obtained in Comparative Example 1 was concentrated under reduced pressure until the water content became 60 wt% with respect to the generated sodium salt of S, S-ethylenediamine-N, N'-disuccinate. ,
To the resulting concentrated residue was slowly added 2.3 times the volume of water of methanol with sufficient stirring. After the addition of methanol was completed, the mixture was stirred for 1 hour, and the precipitated crystals were filtered and dried to obtain sodium S, S-ethylenediamine-N, N'-disuccinate sodium salt at an acquisition yield of 80%. At this time, the content of the lactam cyclized product was 0.5%, and the content of ethylenediaminemonosuccinic acid was 0.2%.

Example 12 S, S-Ethylenediamine-N, N'- obtained in Comparative Example 1
1 part by weight of a spray-dried dried product of iron disuccinate alkali salt is dispersed in 2 parts by volume of ethanol containing 20% by volume of water,
Stirred at room temperature for 60 minutes. Thereafter, the crystals were dried by filtration, and the crystals were dried. The alkali metal salt of S, S-ethylenediamine-N, N'-disuccinate containing 2% of lactam cyclized product and 1.5% of ethylenediaminemonosuccinic acid was purified at a purification yield of 80%. Obtained.

Examples 13 and 14 In the same operation as in Example 1, a magnetite having a BET value of 6.5 (m ² / g) was used instead of magnetite having a BET value of 95 (m ² / g). And a case where hematite having a BET value of 18 (m ² / g) was used. Table 2 shows the results
Shown in

Comparative Examples 2 to 4 In the same operation as in Example 1, a magnetite having a BET value of 6.5 (m ² / g) was used instead of magnetite having a BET value of 80 (m ² / g). And a case where hematite having a BET value of 9 (m ² / g) was used. Table 2 shows the results.

[0037]

Example 15 The powders obtained in Examples 1, 10 and 13 and Comparative Examples 1 and 3 were dissolved to form a 40% aqueous solution, which was stored at 50 ° C. for 1 week, diluted to 1%, and observed in a dissolved state. . In the case of using the crystals obtained in the comparative example, insolubles were observed. On the other hand, no insoluble matter was observed in the case of using the crystals obtained in the examples.

Claims (6)

[Claims] 1. S, S-ethylenediamine-N wherein each of a lactam compound represented by the following general formula (1) and an ethylenediaminemonosuccinic acid represented by the following general formula (2) is 7% by weight or less. , N'-iron disuccinate alkali salts. [M is an ammonium ion or an alkali metal ion] [M is an ammonium ion or an alkali metal ion] 2. S, S-ethylenediamine-N, N′-
2. The alkali metal salt of S, S-ethylenediamine-N, N'-iron succinate according to claim 1, wherein the alkali metal salt of iron disuccinate is an ammonium salt or an alkali metal salt. 3. A concentrated solution of an aqueous solution of an alkali salt of S, S-ethylenediamine-N, N′-disuccinic acid containing more than 7% by weight of a compound represented by the general formula (1) or (2) or The dried product is washed with at least one hydrous lower alcohol selected from the group consisting of methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, isobutyl alcohol and tert-butyl alcohol. 2. The method for producing an alkali salt of S, S-ethylenediamine-N, N'-disuccinic acid according to item 1. 4. Iron oxide and S, S-ethylenediamine-
The N, N'-disuccinic acid alkali salt may be obtained by mixing at least one kind of powdered or thread-shaped metal selected from the group consisting of iron, aluminum, magnesium and zinc, and / or ascorbic acid, isoascorbic acid, formic acid and The method for producing an alkali salt of S, S-ethylenediamine-N, N'-disuccinate according to claim 1, wherein at least one compound selected from the group consisting of oxalic acid is added and reacted. 5. The S, S-ethylenediamine-N, N′- according to claim 1, wherein oxidation and drying of ferrous iron to ferric iron are simultaneously performed by a continuous hot air conveying dryer.
A method for producing an iron disuccinate alkali salt. 6. An iron oxide comprising hematite having a BET value of 10 (m ² / g) or more, magnetite having a BET value of 5 (m ² / g) or more, and goethite having a BET value of 85 (m ² / g) or more. 5. The method for producing an alkali metal salt of S, S-ethylenediamine-N, N'-disuccinate according to claim 4, which is at least one selected from the group.