JPH03190851A - Decoloring of glycine - Google Patents

Abstract

PURPOSE:To completely decolor glycine produced by hydantoin method without adsorption loss by treating an aqueous solution of crude glycine having specific pH prepared by a reaction product solution with an active carbon and a strongly basic anion exchange resin. CONSTITUTION:In producing glycine useful as a food ingredient for processed foods or a raw material for agricultural chemicals and drugs by reacting glycolonitrile with carbon dioxide gas and ammonia, a reaction product solution is concentrated, a concentrated solution from which ammonia and carbon dioxide gas are removed or crude glycine obtained by further separation from the concentrated solution by crystallization method of conventional procedure is dissolved in water to give an aqueous solution of crude glycine having pH >=7. 5, which is treated with an active carbon and a strongly acidic anion exchange resin to remove colored substances effectively, industrially and advantageously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for decolorizing glycine. In particular, it relates to a method for decolorizing glycine obtained by reacting glycolonitrile with ammonia and carbon dioxide gas. Glycine is a useful compound that is widely used as a food additive in processed foods, agricultural chemicals, and as a raw material for medicines.

[Prior art]

Traditionally, glycine has been produced mainly by amination of monochloroacetic acid using monochloroacetic acid and ammonia as raw materials, or by reacting glycolonitrile, which can be synthesized almost quantitatively from hydrocyanic acid and formalin, with ammonia, and then hydrolyzing it with an alkali. The Strecker method, in which glycine is obtained using hydrocyanic acid, and the hydantoin method, in which glycolonitrile, which can be synthesized from hydrocyanic acid and formaldehyde, is reacted with ammonia and carbon dioxide, and then hydrolyzed to produce glycine through hydantoin, are known.

However, in any of the above methods, the resulting glycine is inevitably colored, and various economical decolorizing methods have been developed for this purpose. Industrially, decolorization methods using activated carbon and ion exchange resins are generally known.

As methods for decolorizing glycine, for example,
4-1686 purifies glycine obtained by the Strecker method, monochloroacetic acid method, etc. by treating a crude glycine aqueous solution with a pH of 7 or less with a weakly basic anion exchange resin or a medium basic ion exchange resin at 50°C or less. A method is disclosed.

Furthermore, JP-A-61-72761 discloses a method for producing hydantoin by reacting glycolonitrile with carbon dioxide and ammonia, in which the resulting reaction product liquid is treated with activated carbon in addition to acid treatment. .

However, even if the desired product is the same, the types of coloring substances are often slightly different due to differences in manufacturing methods or reaction conditions.

In particular, when the raw materials are different, the difference in the colored substances produced by-product becomes significant, and the decolorization methods are currently being studied individually.

[Problem to be solved by the invention]

The degree of coloration of the reaction solution obtained by the hydantoin method is lower than that obtained by other methods, but it exhibits a light yellow to brown color, and its decolorization could not be treated with the methods known so far. .

Therefore, an effective method for decolorizing glycine obtained by the hydantoin method has been desired.

[Failure to solve the problem]

As a result of intensive study on the decolorization method of glycine in the hydantoin method glycine production, the present inventors found that PH7.5
The inventors have discovered that colored substances can be effectively removed by treating the above glycine aqueous solution with activated carbon and a strongly basic anion exchange resin, and have completed the present invention. That is, the present invention provides a method for producing glycine by reacting glycolonitrile, carbon dioxide gas, and ammonia in the presence of water, in which an aqueous glycine solution with a pH of 7.5 or higher obtained from a reaction product solution is combined with activated carbon and This is a method for decolorizing glycine, which is characterized by treatment with a strongly basic anion exchange resin.

The method for producing the crude glycine aqueous solution in the present invention includes:
For example, glycolonitrile, ammonia and carbon dioxide, which are produced using hydrocyanic acid and formalin as raw materials, or ammonium carbonate, ammonium bicarbonate, and glycolonitrile, which produce these compounds under reaction conditions, are produced with the optimal glycine yield. in the presence of water at 120 to 200 °C, preferably 150 to 170 °C, at a molar ratio such that
Obtained by reaction at °C. In addition to the remaining ammonia and carbon dioxide gas, the reaction product liquid thus obtained contains glycine, hydantoic acid, glycylglycine, hydantoic acid amide, l-liglycine, hydantoin, 2.5 -Contains diketopiperazine, etc., and is colored yellow to brown.

The crude glycine aqueous solution in the present invention is a concentrated solution obtained by concentrating the above reaction product liquid and separating and removing ammonia and carbon dioxide gas, or a crude glycine obtained by further separating the concentrated solution by a conventional crystallization method, etc. means an aqueous solution dissolved in water.

The pH of this crude glycine aqueous solution can be controlled by the degree of concentration of the reaction product solution, but it is usually pH 7.5-5.
Obtained in the range of 9.

The concentration of the crude glycine aqueous solution can be selected arbitrarily, but
For handling purposes, 5 to 30 wtχ is preferably used. If this concentration is less than 5 wtχ, the cost of concentrating the glycine aqueous solution after decolorization will increase, and if it exceeds 30 wtχ, it will be necessary to keep it warm.

In order to efficiently decolorize the above-mentioned crude glycine aqueous solution, it is preferable to use activated carbon in combination with a strong basic anion exchange resin. For example, by first passing the crude glycine aqueous solution through a column packed with a strong basic anion exchange resin, most of the color is removed. The resulting crude glycine aqueous solution is then passed through an activated carbon-packed tower to give it a Hazen color (APH
Decolorization is possible up to the value where A) is O. In addition, the order in which the crude glycine aqueous solution is passed through the packed tower is first activated carbon,
Next, there is no problem in using a strongly basic anion exchange resin, and the same effect can be obtained.

The strongly basic anion exchange resin and activated carbon used in the method of the present invention are generally available on the market, and examples of the strong basic anion exchange resin include products such as Revachit (Mon 500. MP50 sail MP5008, M500MB,
M500ST M2O3M504MB, M2O3, M6
00MB, M600kaiS, M600G3.0sio3
5), Amber Rai 1-(IR8 to 0L TRA402
．． TRA402BL, IRA400T, 30 to TR8
．． TRA458. ] [A900. IRA904. IRA
938IRA95B, TRA410. IRA411
, TRA910. XT5007. XT5010
．． XT5016 XT5017 XT5021 XT
5028. XT5029), Diaion (SA10A
, S^11A, 5A2OA, S218, PA306.
PA308. P312, PA316. PA318
．． PA406. PA408. PA412. PA4
16. PA418), etc. The ionic form of these ion exchange resins can be either a salt type or an OH type, but the OH type is preferable. Further, there is no problem in using a cation exchange resin for removing cations such as Na contained in the reaction product liquid.

Activated carbon can be used whether the raw material is plants such as coconut shells or minerals such as coal or pitch.
For example, the product name for coconut shell charcoal is “White” IC (Takeda Pharmaceutical).
Coconut shell activated carbon such as Tsurumicol Ic-30 (Tsurumi ■), coal-based products such as CPG, CA11 (Toyo Calgon), and A-BAG (Kureha Chemical) are listed.

In the method of the present invention, the crude glycine aqueous solution is treated with a strongly basic anion exchange resin and activated carbon by a commonly used method of passing the solution through a packed column.

As for the liquid passing method, similarly to the strong basic anion exchange resin and activated carbon, a packed column with a packing length/diameter in the range of 2 or more and 20 or less is used, and the processing speed is usually SV (liquid hourly space velocity) 0. It ranges from 1 to 20. In addition, the processing temperature is 20
~80°C.

〔Example〕

Example 1 50 wt% glycolonitrile aqueous solution 25 per hour
6 g (2,23 mol) and ammonia 230
g (13,4 mo1), carbon dioxide gas 297 g (6,
8 mol) of an aqueous solution containing 2210 g of
N was supplied to the front-type reactor, and the reaction was carried out at a reaction temperature of 150° C. and a reaction pressure of 45 kg/c+fl.

The raw material composition at this time was 1120/NH3/Co2/glycolonitrile-45/6/3/1 molar ratio, and the average residence time corresponded to 4.5 hours. When it became steady, the reaction product liquid was concentrated in a concentrator at 100°C to remove most of water, ammonia and carbon dioxide, and crystallized at 20°C to produce 74g of glycine (purity 98.6) per hour. %) were separated. This precipitation amount is 52% of glycine in the reaction product solution.
Corresponds to w tχ. Dissolve this glycine in water and make 20w
It was used as a t% crude glycine aqueous solution for decolorization. The pH of this aqueous solution was 8.1, and the chromaticity was APHA145.

OH-type strongly basic anion exchange resin (Revachit) MP500Δ) 100% pretreated in the usual manner and activated carbon (C
PG manufactured by Toyo Calgon Co., Ltd.) 100 d was packed separately using two tubular decolorizing towers with a diameter of 2.5 cm, and the crude glycine aqueous solution was poured at 25°C at a rate of 3200 d/h, first into an activated carbon-packed tower, and then into a strongly basic decolorizing tower. 50 kg in anion exchange resin packed tower
The liquid was passed through it. The chromaticity (APH) of the aqueous solution at the outlet of the activated carbon packed tower
A) was 36, and the chromaticity (APHA) of the aqueous solution at the outlet of the strongly basic anion exchange resin packed column was 0. Also,
The pH at this time was 8.0, and the glycine recovery rate was 99.
It was 8%.

Example 2 Using the reaction product liquid obtained in Example 1, the concentration was increased to give 55 wtx of crystallized glycine, which was dissolved with water to give 25 wtx of glycine.
% crude glycine aqueous solution (PH7,7, AP HA210
) was prepared for decolorization. Replace the activated carbon with CPG manufactured by Toyo Calgon Co., Ltd. by using coconut shell charcoal (white 5tC), use a strong basic anion exchange resin (Rebatt) instead of MP500A), use IRA41.0, and use crude glycine aqueous solution
Decolorization was carried out in the same manner as in Example 1, except that 30 kg of liquid was passed through at C. The chromaticity (APH) of the aqueous solution at the outlet of the activated carbon packed tower
A) was 32, and the chromaticity (APHA) of the aqueous solution at the outlet of the strongly basic anion exchange resin packed column was 0. In addition, the pH at this time was 7.9, and the glycine recovery rate was 99.6.
%Met.

Comparative Example 1 The crude glycine aqueous solution obtained by the method of Example 1 was purified with sulfuric acid.
H3.1 was prepared and decolorized in the same manner as in Example 1.

When 20 kg of crude glycine aqueous solution was passed through, the chromaticity (APHA) of the aqueous solution at the outlet of the strongly basic anion exchange resin was 1.
It was 5.

Example 3 and Comparative Example 2 The crude glycine aqueous solution discharged from the activated carbon-packed tower in Example 1 was not treated in the strongly basic anion exchange resin-packed tower, and 50% of the crude glycine aqueous solution was treated with the first Strongly basic anion exchange resins, weakly basic anion exchange resins, medium basic anion exchange resins, non-exchange group ion exchange resins, strongly acidic cation exchange resins, and weakly acidic cation exchange resins shown in the table have the same ion exchange capacity. Naruyoni 2~
After stirring at 40"C for 90 minutes, the chromaticity of the crude glycine aqueous solution was determined, and the decolorization rate compared to before treatment was examined using a photometer. Strongly basic anions were detected even at 370 nm and 430 nm. The decolorizing ability of the exchanged resin was excellent. The results are shown in Table 1.

〔Effect of the invention〕

Decarbonation gas is removed from the reaction product liquid obtained by the hydantoin method.
By removing ammonia and concentrating, a glycine aqueous solution with a pH of 7.5 or higher is obtained, and by treating this directly with activated carbon and a strongly basic anion exchange resin, there is no adsorption loss of glycine, and the color can be completely decolored. The method of the invention improves the production of glycine via hydantoin to an industrially advantageous method.

Claims (1)

[Claims] A method for producing glycine by reacting glycolonitrile, carbon dioxide gas and ammonia in the presence of water,
A method for decolorizing glycine, which comprises treating a crude glycine aqueous solution with a pH of 7.5 or higher obtained from a reaction product solution with activated carbon and a strongly basic anion exchange resin.