JPH11189579A - Production of high purity optically active chelated iron complex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production process for an alkali salt of iron S,S- ethylenediamine-N,N'-disuccinate containing less impuriies especially less compound having a lactam ring. SOLUTION: A high purity alkali salt of iron S,S-ethylenediamine-N,N'- disuccinate is obtained by the process in which an iron oxide is dispersed in an aqueous medium, the resultant reaction liquor is kept at pH 4.5-7 and at a reaction temperature of 70-100 deg.C and S,S-ethylenediamine-N,N'-disuccinic acid or its alkali salt is added continuously or intermittently thereto to carry out a reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for producing an alkali metal salt of S, S-ethylenediamine-N, N'-disuccinate which can be used, for example, in photographic processing agents and fertilizers. .

[0002]

2. Description of the Related Art The present inventors have already disclosed in Japanese Patent Application Laid-Open No. 8-34764 a method for producing an alkali salt of iron S, S-ethylenediamine-N, N'-disuccinate from various iron compounds. . Among them, a method using iron oxide is preferable because impurities hardly enter therein. However, even in a method using iron oxide, raw materials S, S-ethylenediamine-N,
N'-disuccinic acid was decomposed during the reaction, and a considerable amount of the lactam ring compound was changed. This was not preferable because not only economical efficiency but also unnecessary compounds were mixed in the product.

Among the contaminating impurities, a lactam ring compound has an extremely low chelating power as compared with S, S-ethylenediamine-N, N'-disuccinic acid and also has a degradability by microorganisms such as S, S-ethylene. Ethylenediamine-
It was inferior to N, N'-disuccinic acid. As a result, not only did the product performance deteriorate in terms of use, but also the performance was reduced with respect to the environmental load.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a process for producing an alkali salt of iron S, S-ethylenediamine-N, N'-disuccinate which is low in impurities, especially lactam ring compounds.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, the more acidic the S, S-ethylenediamine-N, N'-disuccinic acid is cyclized, the stronger the acidity is. It has been found that the higher the temperature, the faster the cyclization rate of S, S-ethylenediamine-N, N'-disuccinic acid, which chelate iron and the like, is significantly reduced. From these findings, S, S-ethylenediamine-N, N ′
-It has been found that by minimizing the non-chelated state of disuccinic acid as much as possible, the formation of lactam cyclized product can be greatly suppressed, and the present invention has been completed.

That is, the present invention relates to a method for reacting S, S-ethylenediamine-N, N'-disuccinic acid with iron oxide in an aqueous medium. 5-7, keeping the reaction temperature in the range of 70-100 ° C, where S, S-ethylenediamine-N, N '
-High purity S, S- characterized by reacting continuously or intermittently with disuccinic acid or an alkali salt thereof.
This is a method for producing an ethylenediamine-N, N'-disuccinate iron alkali salt.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be carried out as follows. First, an aqueous medium and iron oxide powder are charged into a reaction vessel to obtain a dispersion of iron oxide. As the aqueous medium in the present invention, water or alcohol-containing water can be used, but water is preferably used. As the iron oxide, any iron oxide such as magnetite, goethite, and hematite can be used in the form of powder, but magnetite is preferably used from the viewpoint of reactivity.

The obtained dispersion is heated to 70 to 100 ° C., preferably 75 to 95 ° C., more preferably 80 to 90 ° C., where S, S-ethylenediamine-N, N′-disuccinic acid or S, S S-ethylenediamine-N, N'-
Mono-succinic acid disuccinate is continuously or intermittently added in a form dispersed or dissolved in a powder or an aqueous medium. At this time, the pH of the reaction solution is maintained at 4.5 to 7, preferably 5 to 6.

More specifically, S, S-ethylenediamine-N, N'-disuccinic acid used is equimolar to 1.
It is mixed with an aqueous alkali solution having a molar concentration of 4 times, preferably 1.05 to 1.25 times, to obtain a dispersion or aqueous solution of an alkali salt of S, S-ethylenediamine-N, N'-disuccinic acid. Add intermittently. Also, S, S-ethylenediamine-N, N '
-Dissuccinic acid powder may be continuously or intermittently added to an iron oxide dispersion together with an alkaline aqueous solution to cause a reaction. At this time, if the addition of S, S-ethylenediamine-N, N'-disuccinic acid is faster than the addition of the aqueous alkali solution, the pH will decrease, so that the aqueous alkali solution is always added so that the pH is in the range of 4.5 to 7. Perform reaction while adjusting. And so on.

[0010] S, S-ethylenediamine-N, N'-disuccinic acid used in this reaction can be synthesized by a known method. For example, L-aspartic acid is added to 1,2-halogenoethane in the presence of an alkali metal hydroxide,
Synthesis by heat reaction (Inorganic Ch)
emistry 7 (11) 2405 (1968)), and can be produced using a microbial enzyme. In addition, S, S-ethylenediamine-N, N'-disuccinic acid used in this reaction may contain S-ethylenediaminemonosuccinic acid in an arbitrary ratio. The alkali used here is preferably an alkali metal and ammonia which are generally used as S, S-ethylenediamine-N, N 'disuccinate, but may be an alkaline earth metal or an organic monoamine such as alkylamine.

The time required for the addition depends on the reaction temperature, but is suitably selected from 0.2 hours to 4 hours, preferably from 1 to 3 hours. In this reaction, the addition of iron oxide, a reducing substance such as ascorbic acid or oxalic acid together with iron oxide can further enhance the stability of S, S-ethylenediamine-N, N'-disuccinic acid.

The production of the lactam ring compound in the reaction solution thus obtained is suppressed to 1% or less, and an aqueous solution of an extremely high-purity aqueous alkali salt of S, S-ethylenediamine-N, N'-disuccinate is used. Can be obtained. When the target compound is to be obtained in the form of powder, the reaction solution is filtered to remove insoluble matter, and then subjected to a continuous hot air transport type dryer such as a spray dryer to easily obtain high purity S,
An alkali salt of S-ethylenediamine-N, N'-disuccinate iron can be obtained.

Further, if desired, the remaining divalent iron is oxidized to trivalent iron with molecular oxygen as an aqueous solution, and then a solution having a desired concentration is obtained to obtain high purity S, S-ethylenediamine-N, N '. An aqueous solution of an alkali disuccinate iron salt can be obtained.

[0014]

Embodiments will be described below with reference to embodiments.

Example 1 200 g of water and magnetite (iron content: 70.5) were placed in a 1 L cylindrical flask having a stirrer, a thermometer and a raw material inlet.
%) And 3 g of iron powder were added and heated to 85 ° C. Next, S, S-ethylenediamine-N, N'-disuccinic acid 14
6 g is dispersed in 365 g of water containing 10.2 g of ammonia, and this dispersion is added to the iron oxide dispersion prepared previously using a slurry pump while maintaining the liquid temperature at 80 to 85 ° C. in about 2 hours. did. During this time, the pH of the reaction solution gradually decreased from 7, and changed between 5.5 and 6. After the addition, the temperature was kept at 80 ° C. for 30 minutes and then cooled to room temperature. In this reaction solution, used S, S-ethylenediamine-N,
Only 0.5% of a lactam cyclized product was formed with respect to N'-disuccinic acid, and 10% of divalent iron ions were contained with respect to total iron ions. Next, the obtained reaction liquid was filtered to remove insoluble components, and S, S-ethylenediamine-
7 g of N, N'-disuccinic acid was added to add iron ions and S, S
-Ethylenediamine-N, N'-disuccinic acid was adjusted to an equimolar amount, then dried by a spray drier to obtain 0.5% of a lactam ring compound, 0.2% of ethylenediaminemonosuccinic acid, and the amount of divalent iron ions was all iron ions. 0.5%
S, S-ethylenediamine-N with a purity of 98% or more
193 g of iron N'-disuccinate ammonium salt were obtained.

Example 2 200 g of water and magnetite (iron content: 70.5) were placed in a 1 L cylindrical flask having a stirrer, a thermometer and a raw material inlet.
%) And 3 g of iron powder were added and heated to 80 ° C. Next, S, S-ethylenediamine-N, N'-disuccinic acid 14
6 g was added using a spoon over about 2.5 hours while maintaining the liquid temperature at 80 to 85 ° C. During this time, 150 g of an aqueous solution containing 20.4 g of sodium hydroxide was added to the reaction solution at pH.
Was adjusted so as to be 5 to 6. After completion of the addition, the mixture was kept at 80 ° C. for 15 minutes and then cooled to room temperature. In this reaction solution, used S, S-ethylenediamine-
Only 0.4% of lactam cyclized product based on N, N'-disuccinic acid was formed. After blowing about 8% of the remaining ferrous iron ions to oxidize them, insolubles were removed by filtration. The obtained S, S-ethylenediamine-N,
The amount of the lactam ring compound in the aqueous solution of sodium N'-disuccinate iron salt was determined by the amount of S, S-ethylenediamine-
It was 0.4% with respect to N, N'-disuccinic acid.

Example 3 200 g of water and magnetite (iron content: 70.5) were placed in a 1 L cylindrical flask having a stirrer, a thermometer and a raw material inlet.
%) And heated to 85 ° C. Next, 146 g of S, S-ethylenediamine-N, N'-disuccinic acid was dispersed in 365 g of water containing 10.2 g of ammonia, and this dispersion was heated to a previously prepared iron oxide dispersion using a slurry pump. The addition took about 2 hours while maintaining at 80-85 ° C. During this time, the pH of the reaction solution gradually decreased from 7, and changed between 5.5 and 6. After the addition, the temperature was kept at 80 ° C. for 30 minutes and then cooled to room temperature. The ferrous ions in the reaction solution were oxidized by blowing air into the ferrous ions remaining at 10% of the total iron ions, and then insoluble substances were removed by filtration. The obtained solution contains S, S-
0.1 to ethylenediamine-N, N'-disuccinic acid.
9% of the lactam cyclized product had formed.

Comparative 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% caustic soda, and stirred and mixed at room temperature. In addition, magnetite (iron content 70.5%) 40
g and 3 g of iron powder, and the mixture was heated and reacted at 80 ° C. for 2 hours with sufficient stirring. The reaction solution contains a lactam ring compound.
7% was included. After filtering the obtained reaction solution to remove insolubles, S, S-ethylenediamine-N, N'-
The pH was adjusted to 6 with disuccinic acid. The adjusted liquid was treated with a spray dryer to obtain 195 g of sodium S, S-ethylenediamine-N, N'-disuccinate sodium salt containing 2.5% of a lactam ring compound.

Comparative Example 2 200 g of water and magnetite (iron content: 70.5) were placed in a 1 L cylindrical flask having a stirrer, a thermometer and a raw material inlet.
%) And 3 g of iron powder were added and heated to 80 ° C. Next, S, S-ethylenediamine-N, N'-disuccinic acid 14
6 g was added using a spoon over about 2.5 hours while maintaining the liquid temperature at 80 to 85 ° C. During this time, 150 g of an aqueous solution containing 20.4 g of sodium hydroxide was added to the reaction solution at pH.
Was adjusted to be 3.0 to 4.0, and finally, all the prepared aqueous sodium hydroxide solution was added. After maintaining at 80 ° C. for 15 minutes after completion of the addition, the mixture was cooled to room temperature. In this reaction solution, a lactam cyclized product of 2.1% based on S, S-ethylenediamine-N, N'-disuccinic acid used was produced.

Claims (1)

[Claims] 1. S, S-ethylenediamine-N, N'-
In the method of reacting disuccinic acid with iron oxide in an aqueous medium, iron oxide is dispersed in the aqueous medium and the pH of the reaction solution is adjusted to 4.5.
7, the reaction temperature is maintained in the range of 70 to 100 ° C., and S, S-ethylenediamine-N, N′-disuccinic acid or an alkali salt thereof is continuously or intermittently added thereto for reaction. A method for producing an alkali salt of high-purity S, S-ethylenediamine-N, N'-disuccinate iron.