JPH0481987B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a novel method for producing hydantoin, which is useful as an intermediate for pharmaceuticals and agricultural chemicals.

B. Prior art and problems Conventionally, hydantoin has been produced by a method using cyanate and by the so-called Bucherer-Bergs method. However, this method generally has a low yield, and various improved methods have been reported. For example, a method in which glycolonitrile and ammonium bicarbonate are reacted under closed pressure, followed by acid treatment (Tokuko Sho)
39-24807) and a method in which glycolonitrile and ammonium bicarbonate are reacted under normal pressure in the presence of a secondary amine or tertiary amine (Japanese Patent Application Laid-Open No. 50-671).

However, these methods require that glycolonitrile is particularly unstable and its decomposition causes coloration of the reaction product, that pressure-resistant equipment is required to carry out the reaction under closed pressure, and that acid treatment is not required. There were operational and equipment problems, such as the need for acid-resistant equipment.

The present inventors also developed a method for producing hydantoin by reacting glycinonitrile and ammonium bicarbonate, ammonium carbonate, ammonia and carbon dioxide, or a mixture thereof in water or an aqueous solvent, followed by acid treatment. I found it (Special application 1984-
2692 (Japanese Unexamined Patent Publication No. 146876, 1983)). However, even in this method, glycinonitrile and ammonium bicarbonate,
When reacting ammonium carbonate or ammonia with carbon dioxide or a mixture thereof in water or an aqueous solvent, do not make the reaction time excessively long or leave it for a long time after the reaction, or carbon dioxide will volatilize and the pH will become high. If the product deteriorates, the coloring becomes significant and the cost for refining increases, resulting in an economical disadvantage.

C. Means for Solving the Problems As a result of intensive studies to overcome these problems, the inventors of the present invention found that glycinotrile and ammonium bicarbonate, ammonium carbonate, ammonia and carbon dioxide, or a mixture thereof, were mixed with water or The present inventors have discovered that the presence of a sulfite or acidic sulfite during the reaction in an aqueous solvent significantly prevents coloring of the reaction solution, leading to the completion of the present invention.

The sulfite or acid sulfite to be used in the method of the present invention is not particularly limited, but is an inexpensive and easily handled alkali metal sulfite or acid sulfite, such as sodium sulfite, potassium sulfite, acidic sodium sulfite, acidic sulfite, etc. Potassium sulfite is preferred. Alternatively, sulfur dioxide gas may be directly blown into the solution before the reaction to generate ammonium sulfite or acidic ammonium sulfite. No matter which one is used, there is no particular difference in effectiveness. In addition, some effect can be observed even if a column is filled with granular sulfite or acidic sulfite and glycinonitrile is passed through the column.

The amount of sulfite or acid sulfite added is based on 1 mole of glycinonitrile as the reaction raw material.
It may be from 0.001 to 0.3 mol, preferably from 0.01 to 0.05 mol.

D. Examples Next, typical examples of the method of the present invention will be shown and explained in more detail, but these are merely examples for explanation, and therefore the present invention is not controlled in any way by these examples. It's not a thing.

Example 1 28.0 g (0.5 mol) of glycinonitrile and 84.8 g (1.1 mol) of ammonium bicarbonate were added to 200 g of 15% ammonia water.
Add to g. Additionally, 1.43g of sodium sulfite
(0.011 mol) and reacted at 75°C for 6 hours. Hydantoin was found to be 32.5% by liquid chromatography analysis of the reaction solution.
%, hydantoic acid 7.7%, hydantoic acid amide
It was 42.2%. Further, the absorbance (-log t) of the reaction solution at a wavelength of 400 nm was 8.41.

Example 2 Approximately 250 ml of water was heated to 55°C, and ammonia, 2
Carbon oxide was gassed. 273 g of the resulting solution containing 16.7% ammonia and 17.3% carbon dioxide was reacted with 28.0 g (0.5 mol) of glycinonitrile and 2.3 g (0.022 mol) of acidic sodium sulfite at 75°C for 6 hours. Yield: 29.5% hydantoin, hydantoic acid
10.1%, and hydantoic acid amide 43.0%.
Furthermore, the absorbance of the reaction solution was 3.1.

Example 3 28.0 g (0.5 mol) of glycinonitrile, 94.2 g (1.1 mol) of ammonium carbonate, 168 g of 5% ammonia water
Add to. Furthermore, 1.32 g (0.11 mol) of acidic potassium sulfite was added, and the mixture was reacted at 75°C for 6 hours. The yield was 20.6% hydantoin, 5.7% hydantoic acid, and 29.1% hydantoic acid amide. Further, the absorbance of the reaction solution at a wavelength of 400 nm was 1.98.

Comparative Example 1 27.8 g (0.5 mol) of glycinonitrile and 85.1 g (1.1 mol) of ammonium bicarbonate were added to 200 ml of 15% ammonia water.
Add to g. React at a reaction temperature of 75°C for 6 hours.
Liquid chromatography analysis of the reaction solution revealed that hydantoin was 32.9%.
Hydantoic acid 6.5%, hydontoic acid amide
The yield was 43.3%. The absorbance of the reaction solution at a wavelength of 400 nm was 16.75.

Claims (1)

[Claims] 1. In water or an aqueous solution, with glycinonitrile
A hydantoin is produced by reacting with (A) ammonium bicarbonate, (B) ammonium carbonate, or (C) ammonia and carbon dioxide, or (D) a mixture thereof, characterized by the presence of sulfite or acid sulfite. A method for preventing coloration of a reaction solution.