JP2003192650A - Method for producing alkali metal salt of glycine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an industrially improved method producing an alkali metal salt of glycine useful as a raw material for a food additive of processed food, a medicine or an agrochemical, by hydrolysis of glycinonitrile with an alkali metal hydroxide. <P>SOLUTION: In this method producing the alkali metal salt of glycine by reacting glycinonitrile with the alkali metal hydroxide in the presence of water as solvent, the reaction is carried out in a flow reactor with a stirring tank pressurized under the partial pressure of ammonia &ge;0.2 MPa and the reaction of the reaction mixture is completed in a liquid seal type tubular flow reactor. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the hydrolysis of an alkali metal salt of glycine, which is widely used as a food additive for processed foods, a raw material for medicines, agricultural chemicals, etc., with an alkali metal hydroxide of glycinonitrile. The present invention relates to an industrially improved method of manufacturing.

[0002]

2. Description of the Related Art A method of reacting cyanohydrin with ammonia in the presence of an aqueous solvent and hydrolyzing this to obtain an .alpha.-amino acid is known as the Strecker reaction.
It is known that the reaction of cyanohydrin with ammonia produces secondary amines, Schiff bases, and free hydrocyanic acid in addition to α-aminonitrile (Z. anal, Chem.,
169 (3) 184, U.S. Pat. No. 3,167,582). If the reaction solution is hydrolyzed as it is,
Impurities due to by-products are produced as by-products, and by-products are increased in the hydrolysis reaction process. Further, in the hydrolysis reaction, coloring of the reaction solution will increase.

In Japanese Patent Publication No. 51-24481, α-
A method has been reported in which an amino nitrile is treated with a sulfite or an acid sulfite at neutral or alkaline, and then alkali hydrolysis is performed.

In Japanese Patent Publication No. 56-8023, a tubular reactor is used in which glycolonitrile and ammonia are mixed in a molar ratio of ammonia / glycolonitrile of 5 or more and 20 or less and the flow of the reaction liquid is a piston flow. , 80-150 ℃
It has been reported that the reaction is carried out in the temperature range of 1, and then the hydrolysis is carried out with an alkali metal hydroxide in an equimolar amount or more than glycolonitrile.

[0005]

However, the above-listed methods have the following problems, which is extremely disadvantageous in industrial implementation.

The method disclosed in Japanese Examined Patent Publication No. 51-24448 is as follows.
It is a proposal regarding the stabilization of the raw material glycinonitrile aqueous solution, and according to the Examples, it is only an example of the reaction of dropping glycinonitrile into the caustic soda aqueous solution using a stirred tank reactor, and an example of the continuous flow reaction is Not listed. or,
It is described that the reaction is carried out while removing the generated ammonia, and the reaction pressure is not described. According to the Example, the glycine soda yield is described as 96% or 99%, but there is no description regarding by-products in the hydrolysis reaction.

The method of Japanese Examined Patent Publication No. 56-8023 is mainly a proposal relating to a method for producing glycinonitrile as a raw material. According to the examples, a large amount of hydrocyanic acid is generated in the amination reaction and glycine soda after hydrolysis is used. The yield was 91.8%, and there is no description about coloring.
Moreover, the hydrolysis reaction is carried out in a stirred tank system, and there is no description of reaction time or reaction pressure.

[0008] The conventional proposals relate to the production method and stabilization of the raw material glycinonitrile, and not the hydrolysis reaction method. According to the study by the present inventors, when the reaction is carried out in a stirring tank flow reaction system, the residence time distribution is large, and a short path of the raw material and an excessive retention of the reaction solution are unavoidable. This means that the coloring of the reaction solution progresses, or
It must be said that it is extremely disadvantageous because it causes a large amount of impurities by-produced by the reverse reaction. These problems cannot be solved only by controlling the manufacturing method of the raw material glycinonitrile as proposed in the prior art.

[0009]

Means for Solving the Problems The inventors of the present invention have made extensive studies in order to solve the above problems, and as a result, reacted glycinonitrile and an alkali metal hydroxide in the presence of an aqueous solvent. In the method for producing an alkali metal salt of glycine, the reaction is carried out in a stirring tank flow type reactor which is pressurized so that the partial pressure of ammonia is at least 0.2 MPa or more. By completing the reaction in a liquid ring type tubular flow reactor, it was found that an alkali metal salt of glycine with high yield and little coloring can be obtained by a simple reaction method, and the present invention has been completed.

That is, the present invention comprises the following aspects. (1) In a method for producing an alkali metal salt of glycine by reacting glycinonitrile and an alkali metal hydroxide in the presence of an aqueous solvent, the partial pressure of ammonia is at least 0.2 MPa or more. A method for producing an alkali metal salt of glycine, which comprises reacting in a pressurized stirred tank flow type reactor and completing the reaction of the obtained reaction liquid in a liquid ring tubular flow reactor. (2) The average residence time of the reaction liquid in the stirring tank flow type reactor and the liquid-sealing type pipe flow reactor combined is 3
The method for producing an alkali metal salt of glycine according to (1) above, which is 0 to 120 minutes. (3) The reaction temperature in each of the stirring tank flow type reactor and the liquid ring tubular flow reactor is 40 to 80 ° C., and the ammonia partial pressure in the stirring tank flow type reactor is 0.2 to 1. 0 MPa, and the pressure in the liquid ring tubular flow reactor is a pressure at which the dissolved ammonia in the outlet liquid of the stirring tank flow reactor can maintain a liquid phase (1) or ( 2) The method for producing an alkali metal salt of glycine as described above.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As the alkaline metal hydroxide used as the reaction raw material in the present invention, sodium hydroxide, potassium hydroxide, lithium hydroxide and the like are used, but potassium hydroxide and sodium hydroxide are preferred. Yes, and more preferably sodium hydroxide. These alkali metal hydroxides are previously made into an aqueous solution and supplied to the reactor.

The raw material supply molar ratio in the present invention needs to be at least an equimolar amount or more as an alkali metal hydroxide / glycinonitrile molar ratio, but excess alkali metal hydroxide is supplied by glycine alkali metal salt. In the case of obtaining glycine from the above, the purification load is increased, which is disadvantageous. Therefore, the range is preferably 1 to 1.25, and more preferably 1.05 to 1.15.

Glycinonitrile, which is a reaction raw material in the present invention, is usually obtained by reacting ammonia with glycolonitrile obtained from formaldehyde and hydrocyanic acid. Many proposals have been made regarding the production method of this glycinonitrile, and those synthesized with reference to them are used, but in the present invention, the glycinonitrile reaction solution after the amination reaction is used as it is, that is, ammonia is added. It can be used as a reaction raw material as it is. In many cases, unreacted glycolonitrile and iminodiacetonitrile which is a secondary amine are contained as impurities in the glycinonitrile reaction solution. When this reaction solution is directly subjected to hydrolysis, the contained iminodiacetonitrile is hydrolyzed and converted into an iminodiacetic acid alkali metal salt, and glycolonitrile is hydrolyzed and converted into a glycolic acid alkali metal salt. Alternatively, it reacts with glycinonitrile and is converted to iminodiacetic acid alkali metal salt via iminodiacetonitrile. Therefore, originally, it is advantageous that the amount of by-products in the raw material glycinonitrile is small.

On the other hand, according to the studies by the present inventors, when the hydrolysis reaction is carried out, when the stirring and mixing of the raw materials are insufficient, or the conditions such as reaction temperature and pressure are not appropriate, It was revealed that the by-product of the iminodiacetic acid alkali metal salt was large. That is, the by-product rate of the iminodiacetonitrile content or more contained in the raw material glycinonitrile, resulting in a decrease in the yield of glycine alkali metal salt, to the purification step to obtain glycine from the aqueous solution of glycine alkali metal salt A great load will be applied.

The reaction type in the present invention is a means for solving these problems. That is, the hydrolysis reaction of glycinonitrile is carried out at an ammonia partial pressure of at least 0.2MP.
It is carried out in a stirred tank flow type reactor which is pressurized to be a or higher, and the reaction of the obtained reaction liquid is completed in a liquid ring tubular flow reactor. A pressure control valve is installed at the outlet of the gas phase portion of the stirring tank flow type reactor to maintain the pressure in the reactor. Ammonia is further generated by the hydrolysis reaction, so the system internal pressure is increased. At this time, the solubility of ammonia is retained in the reaction solution. A liquid phase is supplied to the latter-stage reactor, and a pressure control valve is also provided at the outlet of the latter-stage reactor to complete the reaction in a liquid-sealed state without vaporizing the dissolved ammonia. By arbitrarily setting the concentration of ammonia in the system, side reactions can be suppressed and the yield of the alkali metal salt of glycine can be dramatically improved, while the coloration of the reaction solution can be significantly suppressed. .

A liquid ring tubular flow reactor is used as the latter stage reactor in the present invention. The reactor type is generally called a plug flow type tubular flow reactor, and the flow velocity distribution of the fluid flowing in the pipe is uniform, and the reactor type that suppresses short paths and excessive retention of the raw material liquid Is. In the present invention, by using the reactor as the latter stage reactor of the hydrolysis reaction (finisher reactor), it is possible to efficiently complete the reaction in an extremely short time, and to color the product liquid due to excessive retention, The decrease in the yield of glycine alkali metal salt due to the reverse reaction of glycinonitrile can be significantly suppressed.

The reaction time in the present invention, that is, the average residence time is in balance with the reaction temperature. However, if the reaction time is short, it is difficult to complete the reaction, and if the reaction time is long, modified coloring due to excessive retention may occur. It is within a range of 10 to 60 minutes in the tank and 10 to 60 minutes in the latter stage tubular reactor. Preferably, the average residence time of both reactors combined is in the range of 30 to 120 minutes, more preferably 45 to 100 minutes.

The reaction temperature in the present invention is a balance with the above reaction time, but when it is low, it is difficult to complete the reaction, and when it is high, the yield is lowered and the coloring progresses.
It is in the range of 35 to 100 ° C. Preferably 40-90
C., more preferably 50 to 80.degree.

The operating pressure of the first-stage stirring tank flow reactor in the present invention is maintained by the ammonia contained in the raw materials and the ammonia generated by the reaction, and the reaction pressure has an ammonia partial pressure of at least 0.2 MPa or more. Is set. The operating pressure of the reactor is determined in consideration of the reaction temperature and the concentration of the raw materials, but usually the ammonia partial pressure is in the range of 0.2 to 1.0 MPa, preferably 0.3.
To 0.8 MPa, more preferably 0.4 to
It is set to fall within the range of 0.7 MPa. In the latter-stage tubular reactor, the pressure is selected so that the liquid phase can be maintained.

[0020]

EXAMPLES The present invention will be described below with reference to examples. The present invention is not limited to these examples, and various changes and modifications can be made without departing from the spirit of the invention.

[0021]

Example 1 An aqueous glycinonitrile solution was prepared in advance by the following method. A stainless steel autoclave with an internal volume of 4 liters equipped with a stirrer and a jacket was charged with pure water 46
After charging 2 g and purging with nitrogen, hot water was circulated through the jacket so as to keep the internal liquid temperature at 40 ° C. while stirring. Ammonia gas was introduced from a liquid ammonia cylinder to the system, and the pressure was finally adjusted to 0.26 MPa / G (gauge pressure) while the system was replaced with ammonia. Then, using a liquid-sending pump, 600 g of a 56% aqueous solution of glycolic nitrile (glycolonitrile) manufactured by Tokyo Kasei Kogyo Co., Ltd.
It was supplied to the autoclave at a supply rate of Hr. In this method, the ammonia equivalent amount consumed in the reaction is always supplied. The supply of the glycolonitrile aqueous solution was completed in 2 hours, the reaction was completed by further stirring for 1 hour, and the reaction solution was pressure-fed to a stainless steel tank for recovery.
The pressure was further increased with nitrogen gas until the pressure reached 0.4 MPa / G. 2700 g of an aqueous solution containing 23.5 parts by weight of glycinonitrile and 32.7 parts by weight of ammonia was obtained. on the other hand,
Separately, 3000 g of an aqueous sodium hydroxide solution of 37.93 parts by weight was prepared in a stainless steel tank, and the atmosphere was replaced with nitrogen and pressurized with nitrogen.

Using the reaction apparatus shown in FIG. 1, a glycinonitrile hydrolysis continuous flow reaction was carried out in the following manner.
Reactor 1 is a stirred tank flow type reactor, is a jacket type stainless steel autoclave with an internal volume of 200 ml equipped with a stirrer, and warm water is circulated in the jacket to maintain an arbitrary reaction temperature. A nitrile aqueous solution and a sodium hydroxide aqueous solution are supplied. The pump 3 operates to feed the reaction solution to the reactor 2 so that the holdup is maintained at 120 ml by the operation of the attached liquid level gauge. A back pressure valve was installed at the gas phase outlet of the reactor 1 to maintain the internal pressure of the reactor 1 at 0.43 MPa / G. The reactor 2 was a liquid ring type tubular flow reactor, which was a jacketed tubular flow reactor having an inner volume of 120 ml, and warm water was circulated in the jacket to keep it at an arbitrary reaction temperature. A back pressure valve is installed at the outlet of the reactor 2 so that the internal pressure of the system is 0.5M.
It was set to Pa / G. The product glycine soda aqueous solution at the outlet of the back pressure valve was introduced into the product tank and stored in the product tank that was previously kept under a nitrogen atmosphere. After 3 hours had elapsed from the start of the reaction, the outlet liquid of the reactor 2 was sampled in a dilute sulfuric acid aqueous solution for composition analysis and absorbance analysis. The composition of the aqueous glycinonitrile solution used as the reaction raw material is shown in Table 1, the hydrolysis reaction conditions are shown in Tables 2 and 3, and the hydrolysis reaction results are shown in Table 4.
Shown in.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

From this example, according to the method of the present invention, when the glycine alkali metal salt is produced by the continuous flow hydrolysis reaction of glycinonitrile, the glycine alkali metal salt with extremely high yield and little coloring is produced. It turns out that it can be manufactured.

[0028]

Comparative Example 1 The reaction conditions shown in Table 3 above were set to the reaction conditions shown in Table 5 below (the pressure in the stirring tank flow type reactor was 0 MPa / G (normal pressure)), and the reaction was performed while removing the generated ammonia. Others were the same as in Example 1. The results are shown in Table 6.
Shown in.

[0029]

[Table 5]

[0030]

[Table 6]

From this comparative example, in the case where the reaction is carried out while the supplied ammonia and the generated ammonia are removed in the reactor while the pressure in the stirred tank flow type reactor is normal pressure, the reaction system of the present invention is used. Even if it was used, the yield of glycine soda remained at 95.7%, and the sodium salt of iminodiacetate was by-produced in excess of the amount of iminodiacetonitrile contained in the raw material.
Further, it can be seen that the reaction product liquid is also markedly colored.

[0032]

Comparative Example 2 Example 1 was repeated except that the reactor 2 was removed and the residence time in the stirred tank flow type reactor was doubled to carry out the reaction under the hydrolysis reaction conditions shown in Tables 7 and 8 below. The reaction was performed in the same manner as in. The results are shown in Table 9.

[0033]

[Table 7]

[0034]

[Table 8]

[0035]

[Table 9]

From this comparative example, even if the hydrolysis reaction is carried out in a pressurized system, if the reaction is carried out only in a stirred tank flow type reactor, the reaction cannot be efficiently completed, and the reaction will not be completed.
At a residence time of hours, the glycinonitrile conversion is 98.
The yield of glycine soda remains at 95.2%, and the iminodiacetic acid sodium salt is by-produced in excess of the amount of iminodiacetonitrile contained in the raw material.
Further, it can be seen that the reaction product liquid is also markedly colored.

[0037]

According to the present invention, by efficiently completing the hydrolysis reaction of glycinonitrile with an alkali metal, it is possible to obtain an alkali metal salt of glycine with high yield and little coloration by a simple reaction method. You can

[Brief description of drawings]

FIG. 1 is a diagram of a reactor used in Example 1.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4H006 AA02 AC47 BB31 BC10 BC11                       BC19 BD80 BD81 BE10 BE14                       BE60 BU32 NB16                 4H039 CA65 CD50

Claims (3)

[Claims] 1. A method for producing an alkali metal salt of glycine by reacting glycinonitrile with an alkali metal hydroxide in the presence of an aqueous solvent, wherein the partial pressure of ammonia is at least 0.2 MPa or more. Of an alkali metal salt of glycine, characterized in that the reaction is carried out in a stirred tank flow type reactor which is pressurized in the same manner, and the reaction of the obtained reaction solution is completed in a liquid ring tubular flow reactor. Method. 2. The average residence time of the reaction liquid in both the stirred tank flow type reactor and the liquid ring type tubular flow reactor is 30 to 120 minutes. 1
A method for producing the alkali metal salt of glycine described. 3. The reaction temperatures in the stirring tank flow type reactor and the liquid ring type pipe flow reactor are 35 to 1 respectively.
00 ° C., the ammonia partial pressure in the stirring tank flow type reactor is 0.2 to 1.0 MPa, and the pressure in the liquid ring tubular flow reactor is the stirring tank flow type reactor outlet liquid. The method for producing an alkali metal salt of glycine according to claim 1 or 2, wherein the dissolved ammonia is at a pressure capable of maintaining a liquid phase.