JPH04342549A - Production of aminocarboxylic acid salt - Google Patents

Abstract

PURPOSE:To obtain an aminocarboxylic acid salt useful as a raw material for agricultural chemicals and pharmaceuticals, a chelating agent, a food additive, etc., in high yield and selectivity while suppressing the formation of by- products at a low cost enabling the repeated use of a catalyst. CONSTITUTION:The objective aminocarboxylic acid salt can be produced in high quality at a low cost by the oxidative dehydrogenation reaction of a compound of formula (R<1> and R<2> are H, hydroxyethyl, 1-18C alkyl, 2-3C aminoalkyl or 2-3C hydroxyalkylaminoalkyl) in the presence of an alkali metal and/or alkaline-earth metal hydroxide, a copper-containing catalyst and water while keeping the concentration of chromium ion, manganese ion, zinc ion, molybdenum ion or iron ion in the reaction liquid to <=10ppm each. There is little deterioration of the activity and selectivity of the catalyst after the repeated use of the catalyst and, accordingly, the catalyst can be recycled and reused in many times without using a reprocessing step to enable the simplification of the step and the reduction of the catalyst cost and facility cost.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a method for producing aminocarboxylic acid salts useful as agricultural chemicals, raw materials for pharmaceuticals, chelating agents, food additives, and the like.

0002

[Prior Art] A method for obtaining an aminocarboxylic acid salt by reacting an aminoalcohol in the coexistence of an alkali hydroxide, water, and a copper-containing catalyst is known (Japanese Patent Laid-Open No. 60-416
No. 44, JP-A-60-41645, JP-A-60-78
No. 948, JP-A-60-78949, JP-A-60-9
No. 7945, JP-A-60-100545).

In these methods, aminocarboxylic acid salts can be obtained with a high selectivity of about 95%, but for example, when producing glycine salts using monoethanolamine as a raw material, iminocarboxylic acid salts can be obtained using oxalate and diethanolamine as raw materials. When producing acetate, glycine salt is produced, and when producing nitrilotriacetate using triethanolamine as a raw material, by-products such as iminodiacetate and glycine salt are also produced. These by-products not only reduce the yield and product purity of the desired aminocarboxylic acid salts, but also cause problems during the reaction and purification process when the obtained aminocarboxylic acid salts are further converted into derivatives such as pesticides and pharmaceuticals. It has a negative impact and also reduces the overall yield and product purity of the final derivative. Therefore, a method for selectively obtaining aminocarboxylic acid salts in high yield is desired.

Furthermore, since these methods use expensive catalysts, it is desirable to recover the catalyst after the reaction and use it repeatedly to reduce catalyst costs. However, as copper-containing catalysts are repeatedly used, catalytic performance such as catalytic activity and selectivity deteriorates, and there are limits to their recovery and reuse.

[0005]

[Problem to be solved by the invention] The purpose of the present invention is to
The object of the present invention is to provide an economically advantageous method for producing an aminocarboxylic acid salt with few by-products, high yield, high selectivity, and allowing the catalyst to be recovered and used repeatedly.

[0006]

[Means for Solving the Problems] As a result of various studies on methods for obtaining aminocarboxylate salts by oxidative dehydrogenation of amino alcohols using copper-containing catalysts, the present inventors found that
The inventors discovered that the presence of certain metal ions in the reaction solution lowers the activity of the catalyst and promotes the production of the above-mentioned by-products, and as a result of further intensive studies, the present invention was completed. That is, the present invention provides the following general formula (1)

[0007]

[Case 2]

From the amino alcohol represented by In the method of
This is a method for producing an aminocarboxylic acid salt, the gist of which is to carry out the reaction while maintaining the temperature below pm.

According to the method of the present invention, the CH2OH group of the amino alcohol represented by the general formula (1) is oxidized to a COO- group. When R1 and R2 in general formula (1) are hydroxyethyl groups, these CH2OH groups are also COO
It is also within the scope of the present invention to obtain salts of aminocarboxylic acids which are oxidized to - groups, but which have a plurality of such COO- groups.

Examples of the amino alcohol represented by the general formula (1) include monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N,N-dimethylethanolamine, N-ethylethanolamine, and N-ethylethanolamine. Isopropylethanolamine, N-butylethanolamine, N-nonylethanolamine, N-(2-aminoethyl)ethanolamine, N-(3-aminopropyl)ethanolamine, N
, N-diethylethanolamine, N,N-dibutylethanolamine, N-methyl diethanolamine,
N-ethyl diethanolamine, N-isopropyl diethanolamine, N-butyl diethanolamine, N-ethyl, N-(2-aminoethyl)ethanolamine, N-methyl, N-(3-aminopropyl)
Examples include ethanolamine and tetrahydroxyethylethylenediamine.

Using these amino alcohols represented by the general formula (1) as raw materials, the corresponding aminocarboxylic acids can be obtained as alkali metal salts and/or alkaline earth metal salts. As a specific example of the raw material amino alcohol, the resulting aminocarboxylic acid salt, and the main by-products, when monoethanolamine is used as the raw material, the aminocarboxylic acid salt obtained is glycine salt, and the main by-product is oxalate; diethanolamine. The aminocarboxylate obtained when using triethanolamine as a raw material is iminodiacetate, the main by-product is glycine salt; the aminocarboxylate obtained when using triethanolamine as a raw material is nitrilotriacetate, the main by-product is glycine salt. iminodiacetate and glycine salt. Similarly, when other amino alcohols are used as raw materials, the following is an example of the set [amino alcohol: obtained aminocarboxylate: main by-product]: [N-methylethanolamine: N-methylglycine salt: oxalate] , [N,N-dimethylethanolamine: N,N-dimethylglycine salt:
oxalate], [N-ethylethanolamine: N-ethylglycine salt: oxalate], [N-methyldiethanolamine: N-methyliminodiacetate: N-methylglycine salt], [N-isopropyldiethanolamine: N-isopropylimino diacetate: N-isopropylglycine salt], [N-butyldiethanolamine: N-butyliminodiacetate: N-butylglycine salt], [N-ethyl,
N-(2-aminoethyl)ethanolamine: N-ethyl, N-(2-aminoethyl)glycine salt: oxalate],
Examples include [tetrahydroxyethylethylenediamine: ethylenediaminetetraacetate: oxalate, etc.].

The catalyst used in the present invention contains copper as an essential component. Raw materials for copper include metallic copper, inorganic substances such as nitrates, sulfates, carbonates, oxides, halides, and hydroxides, and organic acid salts such as formates, acetates, propionates, and lactates. can also be used. The form of the catalyst is not particularly limited. For example, a catalyst obtained by oxidizing a metallic copper surface and then reducing it with hydrogen, a catalyst obtained by developing Raney copper with an alkaline aqueous solution, an activated catalyst obtained by thermally decomposing and/or reducing copper formate, copper carbonate, etc. Copper can be used as it is, or by being impregnated into an alkali-resistant carrier or supported by electroless plating. Examples of preferred carriers include titanium oxide, zirconium oxide,
Examples include silicon carbide. In particular, from the viewpoint of reaction activity and catalyst life, expanded Raney copper and copper catalysts supported on zirconium oxide or silicon carbide by coprecipitation or impregnation are preferably used. The amount of catalyst used is 1 to 70% by weight, preferably 5 to 50% by weight, based on the amino alcohol. If the particle size of the catalyst used in the present invention is too small, it is disadvantageous when separating the catalyst. For example, when the catalyst is separated by sedimentation, the sedimentation rate is slow, and when the catalyst is separated by filtration, the filtration rate is slow. On the other hand, if the particle size is too large, sedimentation properties will improve, but large stirring power will be required to improve the dispersion of the catalyst.
Furthermore, since the effective surface area of the catalyst decreases, the catalytic activity decreases. Therefore, the particle size of the catalyst is preferably within the range of 2 to 300 microns. However, when this reaction is carried out using a fixed bed flow type reactor, the particle size of the catalyst is preferably larger because it is necessary to reduce pressure loss. Furthermore, if the specific surface area of the catalyst used in the present invention is too small, the catalyst activity will be low and a large amount of catalyst will be used. Therefore, it is preferable that it is 1 m2/g or more in the BET measurement method.

As the alkali metal hydroxide or alkaline earth metal hydroxide used in the present invention, sodium hydroxide, potassium hydroxide, etc. are particularly preferably used. Although flakes, powders, pellets, etc. and aqueous solutions thereof can be used, it is easier to handle them when they are used as an aqueous solution. The amount of the alkali metal hydroxide or alkaline earth metal hydroxide used is at least an equivalent, preferably within the range of 1.0 to 2.0 equivalents, relative to the hydroxyl group of the amino alcohol used in the reaction.

The present invention is carried out in the presence of water. By using water, the amino alcohol and the alkali metal hydroxide can be reacted in a homogeneous system, and as a result, the aminocarboxylic acid salt can be obtained in high yield. The amount of water used in the reaction is 10% by weight or more, preferably 50 to 5% by weight based on the amino alcohol.
00% by weight.

In the present invention, the reaction is carried out at a concentration of chromium ion, manganese ion, zinc ion, molybdenum ion, or iron ion present in the reaction solution, each at 10 ppm or less. These ions affect the catalyst performance, and if the reaction is carried out without satisfying these conditions, the activity of the catalyst will decrease and by-products will increase.

[0016] The reason why these ions are mixed into the reaction solution is that these metal ions are contained in the raw material amino alcohol, alkali metal hydroxide, alkaline earth metal hydroxide, water, or catalyst. In addition, ions may be eluted from the materials that make up the reactor, attached equipment, piping, etc. In particular, this reaction can be carried out in a batch-type stirred tank.
When using a reactor such as a continuous stirred tank or a fluidized bed reactor, the walls of the reactor may be worn away by the catalyst suspended during the reaction. When a material containing iron is used, these ions are likely to be mixed into the reaction solution. Therefore, when using such materials, it is necessary to carefully consider the reaction temperature, stirring conditions, etc. so that the concentration of these ions in the reaction solution does not exceed 10 ppm. In addition, when collecting and repeatedly using the catalyst, it is necessary to carefully consider the selection of materials for the catalyst separation device and storage tank, and the operating conditions of the device.

The reaction temperature is 220° C. or lower, usually 120° C. to 21° C., in order to prevent thermal decomposition and hydrogenolysis of the carbon-nitrogen bonds of the amino alcohol and the produced aminocarboxylic acid.
It is carried out within a temperature range of 0°C, preferably 140-200°C.

Since this reaction is an oxidative dehydrogenation reaction and involves the generation of hydrogen, it is preferable from the viewpoint of reaction rate to lower the reaction pressure as much as possible. Usually, the minimum pressure for proceeding the reaction in the liquid phase or higher, preferably 5 to 50 kg/cm2G
is within the range of

Batch, semi-batch, or continuous reaction methods can be used for the reaction.

After the reaction according to the method of the present invention, the reaction mixture is filtered to separate the catalyst, and an aqueous solution of the desired aminocarboxylic acid salt is obtained as a filtrate. Alternatively, the reaction mixture is allowed to stand still to allow the catalyst to precipitate, and the desired aqueous solution of the aminocarboxylic acid salt is obtained as a supernatant liquid. The aqueous solution of the aminocarboxylic acid salt thus obtained can be appropriately purified as required to obtain a high-quality aminocarboxylic acid salt as a product. On the other hand, the catalyst separated by filtration or sedimentation can be recovered and reused as is for the next reaction. Of course, the recovered catalyst may be used after being appropriately regenerated as required.

[0021]

EFFECTS OF THE INVENTION According to the method of the present invention, the desired aminocarboxylic acid salt can be produced in high yield and high selectivity with few by-products such as oxalate and glycine salt. In addition, even when the catalyst is recovered and used repeatedly, there is little decline in catalyst activity or selectivity, and in most cases, the catalyst can be recycled and reused many times without the need for a catalyst regeneration process. can be simplified, catalyst costs and equipment costs can be reduced, and high-quality products can be supplied at low cost.

[0022]

[Examples] The present invention will be specifically explained below with reference to Examples. However, the present invention is not limited to these Examples.

[0023] Here, the conversion rate of amino alcohol and the selectivity of aminocarboxylic acid are derived from the following formula.

Conversion rate of amino alcohol (%) = Number of moles of reacted amino alcohol/Number of moles of amino alcohol subjected to reaction x 100 Selectivity of aminocarboxylic acid (%) = Number of moles of aminocarboxylic acid produced/ Number of moles of reacted amino alcohol ×
100 Example 1 80 g of diethanolamine, 64 g of sodium hydroxide,
170g of water, average particle size 20μ, BET surface area 1
9m2/g of developed Raney copper (8g) is made of stainless steel with a supernatant liquid extraction pipe and lined with copper metal, with an internal volume of 500.
ml into an autoclave, and after internally purging with hydrogen gas three times, the reaction temperature was 170°C and the reaction pressure was 10kg/c.
The reaction was carried out at m2G until no hydrogen was generated. The time required for the reaction was 5 hours after the temperature was raised to 170°C. After the reaction was completed, the temperature was lowered to 80° C., and after standing at this temperature for 10 minutes, 283 g of supernatant liquid was extracted from the supernatant liquid extraction tube.

[0025] When the extracted supernatant liquid was analyzed by isotachophoresis, the conversion rate of diethanolamine was 99.
．． 2%, selectivity of sodium iminodiacetate is 99.3%
, and the selectivity of by-produced glycine sodium is 0.5
%Met. Note that the amount of supernatant liquid remaining in the autoclave was known in advance, and these values were taken into account. In addition, no suspended matter was observed in the extracted supernatant, and as a result of analysis using atomic absorption spectrometry, iron ions were found to be 2 ppm, but chromium ions, manganese ions, zinc ions, and molybdenum ions were not detected. (less than 1 ppm).

The following repeated experiments were conducted using the catalyst remaining in the autoclave to examine the repeated activity of the catalyst.

An aqueous solution consisting of 64 g of sodium hydroxide and 170 g of water was added to the autoclave, stirring was started, 80 g of diethanolamine was added, and the experiment was repeated under the same reaction conditions as the first time. When this operation was repeated until the catalyst was used 10 times, the reaction time required for the 10th time was 8 hours after the temperature was raised, and as a result of analyzing the supernatant liquid from the 10th time, the conversion rate of diethanolamine was 99.0.
%, the selectivity of sodium iminodiacetate was 98.4%, and the selectivity of by-produced sodium glycinate was 1.2%. Further, as a result of analysis by atomic absorption spectrometry, iron ions were found to be 2 ppm, but chromium ions, manganese ions, zinc ions, and molybdenum ions were not detected.

Example 2 An aqueous sodium hydroxide solution was added to a solution of 24.8 g of zirconium oxychloride and 4.0 g of copper nitrate dissolved in 300 ml of water to precipitate the hydroxide. The precipitate was washed with water, dried, and then exposed to air. Heat treated at 500°C for 3 hours, then heated in a hydrogen stream for 2 hours.
A catalyst containing copper and zirconium was prepared by reduction treatment at 30° C. for 6 hours. This catalyst had an average particle diameter of 2 μm and a BET surface area of 61 m 2 /g.

The reaction was carried out under the same conditions as in Example 1, except that 8 g of this copper- and zirconium-containing catalyst was used in place of the developed Raney copper. The time required for the reaction was 5 hours after the temperature was raised to 170°C. After the reaction was completed, the temperature was lowered to 80° C., and after standing at this temperature overnight, 283 g of supernatant liquid was slowly drawn out from the supernatant liquid extraction tube.

A small amount of suspended matter was observed in the supernatant liquid taken out. When the supernatant was filtered and analyzed, the conversion rate of diethanolamine was 99.0%, the selectivity of sodium iminodiacetate was 99.5%, the selectivity of sodium glycinate was 0.4%, and the selectivity of sodium ion was 99.0%. Although the amount was 2 ppm, chromium ions, manganese ions, zinc ions, and molybdenum ions were not detected.

Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that a stainless steel autoclave was used until the catalyst was used three times. The reaction time required for the third time was 13 hours after the temperature was raised. As a result of analyzing the supernatant liquid extracted after the third reaction, the conversion rate of diethanolamine was 97.5%, the selectivity of sodium iminodiacetate was 93.5%, and the selectivity of by-produced sodium glycinate was 3.5%. there were. Further, 25 ppm of iron ions and 10 ppm of chromium ions were detected.

As described above, in Comparative Example 1, the catalyst activity decreased,
The decrease in selectivity was more remarkable than in Example 1.

Comparative Example 2 When preparing raw materials, 1 ferrous chloride was added instead of 170 g of water.
170 g of water containing 26 ppm was used (therefore, 30 ppm of iron ions were added to the raw materials)
The reaction was carried out once in the same manner as in Example 1 except for the following. The time required for the reaction was 10 hours after the temperature was raised to 170°C. After the reaction was completed, the reaction mixture was cooled and filtered to obtain a reaction product as a filtrate. As a result of analyzing the filtrate, the conversion rate of diethanolamine was 98.5%, the selectivity of sodium iminodiacetate was 97.3%, and the selectivity of by-produced sodium glycinate was 2.3%.

Comparative Example 3 When charging raw materials, chromium nitrate (
III) The same operation as in Comparative Example 2 was performed except that 170 g of water containing 254 ppm of chromium ions was used (therefore, 30 ppm of chromium ions were added to the raw materials). The time required for the reaction was 12 hours after the temperature was raised to 170°C. Analysis of the filtrate revealed that the conversion rate of diethanolamine was 98.5% and the selectivity of sodium iminodiacetate was 96.
1%, and the selectivity of by-product sodium glycine is 3.2%.
Met.

Comparative Example 4 When charging the raw materials, 170 g of water containing 97 ppm of molybdenum chloride (II) was used instead of 170 g of water (therefore, 30 ppm of molybdenum ions were added to the raw materials). The same operation as in Comparative Example 2 was performed. The time required for the reaction was 7 hours after the temperature was raised to 170°C. Analysis of the filtrate revealed that the conversion rate of diethanolamine was 99.1% and the selectivity of sodium iminodiacetate was 95.
0%, selectivity of by-product sodium glycinate is 4.2%
Met.

Comparative Example 5 When charging raw materials, 19 g of zinc bromide was added instead of 170 g of water.
170g of water containing 1ppm was used (therefore, 30ppm of zinc ions were added to the raw materials)
The other operations were the same as in Comparative Example 2. The time required for the reaction was 9 hours after the temperature was raised to 170°C. As a result of analyzing the filtrate, the conversion rate of diethanolamine was 97.9%, the selectivity of sodium iminodiacetate was 93.1%, and the selectivity of by-produced sodium glycinate was 4.8%.

Claims (1)

[Claims] [Claim 1] An amino alcohol represented by the following general formula (1) [Claim 1] in the coexistence of an alkali metal hydroxide and/or an alkaline earth metal hydroxide, a copper-containing catalyst, and water. A method for producing an aminocarboxylic acid salt by the oxidative dehydrogenation reaction of A method for producing an aminocarboxylic acid salt.