JPS6183164A - Preparation of hydrantoin - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as an agricultural chemical, medicine or intermediate raw material therefor in high quality and further in high selectivity and yield without coloring, by reacting glycolonitrile with carbon dioxide and ammonia under limitations on both the molar ratio of the carbon dioxide to the ammonia in the reaction system and the concentration of the glycolonitrile in the reactive system. CONSTITUTION:In preparation of hydantoins by reacting glycolonitrile with carbon dioxide and ammonia, carbon dioxide and ammonia are fed in such a way that the molar ratio thereof (CO2/NH3) is set at >=0.7, preferably within 0.75-1.5 range and glycolonitrile is fed in such a way that the concentration thereof does not exceed 1.1%. The reaction is preferably carried out by the semi-batch method since the concentration of the glycolonitrile in the reaction system is easily controlled at <=1.1%.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing hydantoin, and more particularly to a method for producing hydantoin in a high yield, with extremely few impurities, and in the form of white crystals.

It has long been known that hydantoin provides α-amino acids through condensation reactions with various aldehydes.
Substituted hydantoin, which is used industrially as a raw material for the production of amino acids, and into which substituents have been introduced, is also a useful compound as a pharmaceutical, a pharmaceutical, or an intermediate raw material for the production thereof.

(Prior Art) It is known that the production of unsubstituted hydantoin by the so-called Bucherer-Bergs reaction, which is systematized as a method for synthesizing 5-substituted hydantoin, is insufficient in terms of yield and product quality (H, R.

Henry et al. J, A, C, S; 64,522. (1
942)).

However, various improved methods have been proposed since then, but all of them focus on improving the yield, and no method has been proposed for producing white crystals with high commercial value in good yield. For example, the method of JP-A-54-138557 proposes a reaction using a mixed solvent of water and water-soluble alkoxyethanols, but in order to obtain a white crystal product, reconsolidation and activated carbon treatment are required. is required, and the operation for recovering the solvent after the reaction is complicated.

(Problems to be Solved by the Invention) The present inventors have improved the drawbacks seen in the prior art, and produced hydantoin with high yield, high selectivity, and significantly improved coloring by the cyanohydrin method. Various studies were conducted to find a method for economically producing high-quality hydantoin.

As a result, they discovered that the objective could be achieved by limiting the molar ratio of ammonia to carbon dioxide gas in the reaction system and the glycolonitrile concentration in the reaction system, and arrived at the present invention.

(Means for solving the problem) That is, the present invention uses water as a reaction solvent to react with glycolonitrile.
l) In a method for producing hydantoin by reacting carbon dioxide and ammonia with carbon dioxide and ammonia, (a) carbon dioxide and ammonia are supplied in such a manner that the molar ratio of both in the reaction system is carbon dioxide/ammonia ≧0.7; and (b) the concentration of glycolonitrile in the reaction system is 1.1.
% of glycolonitrile.

In the method of the present invention, the relationship between the amounts of the raw materials glycolonide 1,1, carbon dioxide, and ammonia in the reaction system is important. That is, the molar ratio of carbon dioxide/ammonia in the reaction system is 0.7 or more, preferably 0 from the economic point of view.
．． Supply in the range of 75-1.5.

If this molar ratio is less than 0.7, the coloring of the reaction mixture will be significant, and the crystals of hydantoin, the reaction product, will become pale yellow.
(However, the yield also decreases.

On the other hand, if the molar ratio exceeds 1.5, the influence on hue and yield is small, but the reaction pressure becomes abnormally high, which is economically disadvantageous and undesirable.

In the method of the present invention, ammonium carbonate or ammonium bicarbonate can also be used instead of carbon dioxide gas and ammonia. In addition, the molar ratio of ammonium and carbon dioxide to glycolonitrile is as follows.

Carbon dioxide/Glycolonitrile ≧1.0 Ammonia/
"+) Colonitrile ≧1.2 Carbon dioxide, ammonia and glycolonitrile are used so as to satisfy this relationship.

In the method of the present invention, the concentration of glycolonitrile in the reaction system is 1.1 or less.

When the glycolonitrile concentration exceeds 1.1%, the coloring of the liquid becomes significant and the yield also decreases. This is presumed to be because glycolonitrile reacts with aminoacetonitrile, which is an intermediate. That is, in order to improve the hue and yield, it is necessary to set the molar ratio of carbon dioxide / ammonia to 0.7 or more in order to shorten the existence time of aminoacetonitrile produced as an intermediate as much as possible, In addition, in order to suppress side reactions of the produced aminoacetonitrile, the concentration of glycolonitrile in the reaction system was set at 1°1.
% or less.

Further, the reaction may be carried out either batchwise or continuously, but it is preferable to carry out the reaction semi-batchwise because it is easier to control the glycolonitrile concentration in the reaction system to 1.1% or less.

The reaction is preferably carried out under sealed pressure, and the reaction temperature is usually 60 to 150°C, preferably 80 to 120°C.
°C range.

The reaction time varies depending on the reaction temperature, but is usually 0.25~
The range is 5 hours.

After the reaction, an acid such as sulfuric acid or hydrochloric acid is added to the obtained crude product so that the acid concentration is 10~30% by weight, and the temperature is 70~30% by weight.
Perform acid treatment at 100°C for 2 to 3 hours,
Hydantoic acid and hydantoic acid amide can be cyclized to hydantoin.

(Operation and effect of the invention) The advantages brought about by the invention are as follows.

(1) The selectivity of the reaction is high and most of the by-products are hydantoic acid amide.
By acid treatment at 0 to 100 DEG C. for 12 to 3 hours, the by-product is easily converted to hydantoin, and the yield reaches 90 DEG or more.

(2) Since the process is carried out under conditions of excess carbon dioxide gas, amines are produced as by-products and colored components are reduced, and white crystalline hydantoin can be easily obtained by methods such as activation post-treatment.

(3) Since the reaction is possible even at high temperatures of 80 to 120°C or higher, the reaction time can be shorter than conventional methods.

That is, by the Ω method of the present invention, hydantoin with an excellent brown hue can be obtained in extremely high yield.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

Note that the chromaticity in the Examples was measured by the following method.

Potassium chloroplatinate (K2PtC1,)2.49, crystalline cobalt chloride (CoC12.6H20)2. (Add 200ml of concentrated hydrochloric acid and dissolve, then dilute to 11% with water.

The absorbance of this liquid at a wavelength of 370 ma was measured using a colorimeter, and this was defined as a chromaticity of 1000 degrees.
The chromaticity of the diluted product was set to 100 degrees.

Example 1 Ammonium bicarbonate 150.99.28.10% ammonia aqueous solution 3 was placed in a glass pressure-resistant reaction vessel with an internal volume of 1000 i equipped with a pressurized sampling device and a stirring device.
Charge 8.5 g and 510.69 g of pure water and heat to 100°C. (CO2/NH2=0.75 molar ratio).

When the temperature reached 100°C, 72.69 g of 50% by weight glycolonitrile was charged over a period of 1 hour (NH8/glycolonitrile = 4.0 molar ratio). The charging speed is 1.21
g/min. After charging, the mixture was reacted for 1 hour and concentrated under reduced pressure to obtain 28.6 g of hydantoin (yield: 45 g) and 34.5 g of hydantoic acid amide (yield: 46%).

Sampling was carried out 30 minutes after the start of charging glucolonitrile, total cyanide was analyzed by the method described in JISKO102, and when converted to unreacted glycolonitrile, the glycolonitrile concentration was 0.6%. Furthermore, immediately after charging the glycolonitrile, sampling was carried out and analyzed in the same manner, and the conversion was found to be 0.8. Aminoacetonitrile (NH2CH2CN), which is considered as an intermediate, was not detected as a cyanide compound by the method of JISKO102.

After concentration, acid treatment was performed by refluxing with 20 sulfuric acid for 3 hours, and the resulting solution was passed through an activated carbon layer packed in a 150 mm x 15 φ column to neutralize it, and further concentrated to produce white hydantoin.
49 (yield 87%) was obtained. The chromaticity of the liquid after passing through activated carbon was 250.

Examples 2 to 4, Comparative Example 1 Using the same reactor as in Example 1, the amounts of ammonium bicarbonate and ammonia aqueous solution were varied to examine the influence of the molar ratio. Table 1 shows the results.

After charging the crude reaction solution with glycolonitrile in Example 1,
This represents the reaction solution that was stirred for 1 hour.

The molar ratio of NH3/glycoronidol was fixed at 4.0,
Other conditions were the same as in Example 1.

Table 1 Comparative Example 10 With chromaticity, white crystals were not obtained even if decolorized by the method of Example 1. In Examples 3 to 5, white crystals were obtained. The carbon dioxide/ammonia molar ratio is preferably 0.7 or more.

Comparative Example 2 One part of ammonium bicarbonate was added to the pressure-resistant reaction vessel of Example 1 at room temperature.
Charge 50.9 g, 38.5 g of 28.10 thiammonia aqueous solution, 510.6 g of pure water, and 72.6 g of 50% by weight glycolonitrile, and seal the container (CO2/NH3=0.
75 molar ratio, NH3/glycolonitrile = 4.0 molar ratio). 1.25 hours required to raise the temperature to 100°C, 100°C
When the concentration of glycolonitrile reached 1.2, sampling was performed and the concentration of glycolonitrile was determined. then 100
The reaction was carried out for 2 hours at 'C.

The yields of hydantoin and hydantoic acid amide were 39% and 36%, respectively.

Purification with acid treatment and activated carbon was carried out in the same manner as in Example 1. The hydantoin yield was 71%, and the color of the crystals was pale yellow. The chromaticity of the liquid after passing through activated carbon is 5
It was 10.

Examples 5 to 7, Comparative Example 3
Implementation '1 in the same glass pressure-resistant reaction vessel as in Example 1.
Charcoal: Ammonium acid 150.9! 7.28.
10 thiammonia water 28.1 solution 38.5 ri,
Pour 510.62 ml of pure water and heat to 100°C. When the temperature reached 100℃, 50% by weight of glue was added.
2.6g of IJ Lure is charged intermittently over an hour, then split into minutes (CO2 H3 =
0.75 molar ratio, NH5/g and real 1 liquoronitrile = 4.0 molar ratio). White 1 with the number of divisions and
As in Example 1, analysis of glycolonitrile was carried out in 5.
Table 2 shows the results obtained on that day, concentration, and acid treatment.
Shown below.

Table 2: Column 154. Pour in 427.6% pure water, seal, and add carbon dioxide to 84%. Supplied from Og (C0
2H, = 0.75 molar ratio).

After heating to 3100° C., the same method as in Example 1 was carried out, and finally crystals with a hydantoin reaction yield of 81 cm were obtained.

The chromaticity of the existing R liquid was 230.

Claims (1)

[Claims] 1) A method for producing hydantoin by reacting glycolonitrile with carbon dioxide and ammonia, in which (a) the molar ratio of carbon dioxide and ammonia in the reaction system is carbon dioxide/ammonia≧0. (b) the concentration of glycolonitrile in the reaction system is 1.1.
A method for producing hydantoin, characterized in that glycolonitrile is supplied in an amount not exceeding %.