JPH05320106A - Method for storing glycine or an aqueous solution of its metallic salt - Google Patents

Abstract

PURPOSE:To store glycine or aqueous solution of its metallic salt so as to prevent colored glycine or colored matter in an aqueous solution of its metallic salt from sticking to the inner wall of piping or a storage tank, etc., and so as not to make the cleaning and removal difficult. CONSTITUTION:A colored glycine or an aqueous solution of its metallic salt is stored under inert gas atmosphere. Dissolved oxygen in the aqueous solution is preferably <=0.3mg/l, especially <=0.1mg/l. When an aqueous solution of a glycine sodium salt (dissolved oxygen 0.3mg/l) colored to reddish brown was introduced into a glass vessel and a SUS test piece was put therein and the test piece was retained at 40 deg.C for 48hr in a state where a vapor phase part was completely substituted with a nitrogen gas (having <=1% oxygen concentration) and then taken out therefrom, sticking of the colored matter to the taken- out test piece was not entirely observed and the colored matter was readily removed from the test piece by washing the test piece with water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for storing an aqueous solution of colored glycine or a metal salt thereof, more specifically,
The present invention relates to a method for storing an aqueous solution of glycine or a metal salt thereof, which can prevent coloring of the inner wall of a storage tank or the like by a colored aqueous solution of glycine soda.

Glycine or a metal salt thereof is widely used as a food additive, a drug, etc., and as an intermediate for various industrial products.

[0003]

2. Description of the Related Art Conventionally, for the production of glycine or its alkali metal salt, for example, glycinonitrile obtained by synthesizing glycolonitrile from hydrocyanic acid and formaldehyde and then aminated with ammonia or the like is treated with alkali such as sodium hydroxide. By hydrolysis, a method of obtaining hydantoin from alkali cyanide, formaldehyde and ammonium carbonate, and hydrolyzing this, oxazolidine is synthesized from glycinonitrile and a ketone, and then,
This is carried out by a method of hydrolyzing this with an alkali such as sodium hydroxide. The aqueous solution of glycine or a metal salt thereof obtained by such a method usually contains yellow to reddish brown because it contains various by-products formed in the production process.

[0004]

However, when a colored aqueous solution of glycine or a metal salt thereof as described above is transported or stored, a yellow or reddish brown colored substance is formed on the inner wall of a pipe or a storage tank. There is a problem that not only is it laborious to clean because it adheres and does not peel off easily, but also a special expensive cleaning agent must be used.

An object of the present invention is to provide a novel method for preserving a colored aqueous solution of glycine or a metal salt thereof, which can solve the above-mentioned conventional problems.

[0006]

Means for Solving the Problems As a result of intensive investigations by the present inventors in order to achieve such an object, oxygen in the gas phase and dissolved oxygen in glycine or an aqueous solution of a metal salt thereof have been identified as pipes or storage tanks for colored objects. It was found that the colored glycine or its metal salt aqueous solution was stored in an inert gas atmosphere to prevent the colored substances from sticking to the inner walls of pipes and storage tanks. The present invention has been achieved for the first time by finding out what to obtain.

That is, the present invention is a method for preserving glycine or an aqueous solution of a metal salt thereof (hereinafter, referred to as the first invention), which is characterized in that a colored aqueous solution of glycine or a metal salt thereof is preserved in an atmosphere of an inert gas. And the same as the above-mentioned first invention, except that the dissolved oxygen in the colored aqueous solution of glycine or its alkali metal salt is 0.3 mg / l or less. It is called an invention).

The present invention will be described in detail below. The present invention can be applied to colored glycine or its metal salt aqueous solution obtained by various known methods. As the metal salt, alkali metal salts of glycine such as sodium and potassium are particularly suitable.

The concentration of glycine or its metal salt is not particularly limited, and can be selected from the concentration within the arbitrary range below the saturation concentration at the storage temperature. Usually 10-7
It is selected from concentrations in the range 0% by weight, preferably 20-60% by weight.

In the method of the present invention, the colored aqueous solution of glycine or its metal salt is stored under an inert gas atmosphere.

The inert gas is not particularly limited as long as it is inert to the colored aqueous solution of glycine or its metal salt and the colored substance therein, but nitrogen, argon and the like are preferable.

The material of the inner wall of the storage tank for storing the colored glycine or its metal salt aqueous solution may be glass, plastic, steel or the like, but steel such as SUS is preferable.

Usually, an aqueous solution of colored glycine or a metal salt thereof is introduced into the storage tank, and then the gas phase part is replaced with an inert gas. At that time, the atmosphere is replaced so that the oxygen concentration in the gas phase portion is 5% or less, preferably 1% or less.

When the dissolved oxygen in the colored aqueous solution of glycine or its metal salt is high, the dissolved oxygen concentration is adjusted to 0.3 mg / l or less, preferably 0.1 mg / l or less by blowing an inert gas. ..

Thus, by keeping the colored glycine or the metal salt aqueous solution thereof in an inert gas atmosphere and storing it at about 20 to 80 ° C., it is possible to prevent the coloring matter from sticking to the inner wall of a pipe, a storage tank or the like. The inner wall can be easily cleaned without using a cleaning agent.

[0016]

EXAMPLES Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 (1) Preparation of Glycine Soda Aqueous Solution Aqueous solution of glycolonitrile 50% and aqueous 25% ammonia were added to ammonia / glycolonitrile = 6/1 (molar ratio).
At 70 ° C. and 30 atm for 30 minutes in an autoclave, the resulting glycinonitrile (aminoacetonitrile) is flushed with ammonia, and then a 48% sodium hydroxide aqueous solution is added to sodium hydroxide / glycinonitrile = 1. Add to be 2/1 (molar ratio), 80 ℃
And hydrolyzed for 60 minutes. The obtained reaction product was concentrated to obtain a 45% glycine soda aqueous solution. The glycine soda aqueous solution thus obtained was reddish brown and the dissolved oxygen concentration in the aqueous solution was about 0.3 mg / l.

(2) Adhesion test of colored material to test piece Aqueous glycine soda solution 1 obtained in the above (1)
00 ml was introduced into a glass container. Then, SUS30
The test piece of No. 4 was put in, and the gas phase portion was completely replaced with nitrogen gas (oxygen concentration of 1% or less). After holding at 40 ° C. for 48 hours in this state, the test piece was taken out, and no adherence of colored matter to the test piece was observed, and the test piece could be easily washed with water.

[Comparative Example 1] In Example 1, after the gas phase portion was similarly maintained under an air atmosphere without substituting with nitrogen gas, the test piece was taken out, and it was found that the coloring matter was fixed to the test piece. It was And this fixed matter could not be removed by washing with water.

[Example 2] In Example 1, nitrogen gas (oxygen concentration of 1% or less) was blown into the colored glycine soda aqueous solution introduced into the container so that the dissolved oxygen concentration in the glycine soda aqueous solution was 0.1 mg / The test was conducted in the same manner as in Example 1 except that the temperature was 1 or less and the holding temperature was 80 ° C. When the state of adherence of the colored matter to the test piece was examined, the adherence of the colored matter to the test piece was not seen, and it was possible to easily wash with water.

[0021]

According to the storage method of the present invention, the colored material is fixed to the inner wall of the pipe or the storage tank by a simple method of storing the colored glycine or its metal salt aqueous solution in an inert gas atmosphere. Can be prevented, and the inner walls thereof can be easily cleaned without the need for using a special expensive cleaning agent, and a remarkable effect with unprecedented industrial value can be achieved. Therefore, the storage method of the present invention is generally applied as it is to the colored crude glycine aqueous solution after glycine synthesis. On the other hand, it is considered that the colored crude glycine is purified and stored as crystals of glycine or a salt thereof and then stored, which is more stable than storage in an aqueous solution. However, in industrial processes, it is often the case that the colored crude glycine solution is stored as it is for a certain period of time, or is purified after being transported to another place. It is apparent that the storage method of the present invention is particularly suitable as a storage method in such a case in terms of its effectiveness and low cost. In addition, as the above storage period,
Usually, 1 to 30 days, especially about 2 to 7 days are expected.

Claims (2)

[Claims] 1. A method for storing glycine or an aqueous solution of a metal salt thereof, which comprises storing the colored aqueous solution of glycine or a metal salt thereof under an inert gas atmosphere. 2. The storage method according to claim 1, wherein the dissolved oxygen in the colored aqueous solution of glycine or its alkali metal salt is 0.3 mg / l or less.