JPS61167670A - Method of preventing coloring in hydantoin production - Google Patents

Abstract

PURPOSE:To obtain hydantoin while preventing coloring, by reacting glycinonitrile with ammonium bicarbonate, ammonium carbonate, or ammonia and carbon dioxide or their mixture in the presence of a sulfite or an acidic sulfite in water or in an aqueous solvent. CONSTITUTION:In reacting glycinonitrile with ammonium bicarbonate, ammonium carbonate or ammonia and carbon dioxide or their mixture in water or an aqueous solvent, 0.001-0.3mol, preferably 0.01-0.05mol based on 1mol glycinonitrile of a sulfite or an acidic sulfite (especially sodium sulfite, potassium sulfite, acidic sodium sulfite, acidic potassium sulfite is preferably inespensive and easily handleable) is added to the reaction mixture, and coloring of the reaction solution is prevented, to produce hydantoin. USE:An intermediate for medical drugs and agricultural chemicals.

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.

BACKGROUND OF THE INVENTION Conventionally, hydantoins have been produced by a method using cyanic acid groups and a so-called Bucherer-Bergs method. However, this method generally has a low yield, and various improved methods have been reported. Publication No. 39-24807), a method of reacting glycolonitrile and ammonium bicarbonate in the presence of a secondary amine or a tertiary amine at atmospheric pressure (Japanese Patent Application Laid-Open No. 5-1999)
O-871) etc.

However, these methods require that glycolonitrile is particularly unstable and this decomposition causes coloration of the reaction product.
There were operational and equipment problems, such as the need for pressure-resistant equipment in order to conduct the reaction under closed pressure, and the need for acid-resistant equipment in order to carry out acid treatment.

The present inventors also developed a method for producing hydantoin by reacting glycinonitrile with ammonium bicarbonate, ammonium carbonate, ammonia and carbon dioxide, or a mixture thereof in water or an aqueous solvent, followed by acid treatment. I discovered (patent application 1982-2f192) that this method also uses glycinonitrile and ammonium bicarbonate,
When ammonium carbonate or ammonia and carbon 21ide or a mixture thereof are reacted in water or an aqueous solvent,
If the reaction time is excessively long, if it is left for a long time after the reaction, or if the 2M carbon evaporates and the pH increases, the coloration will become significant and the cost of purification will increase, which is economically disadvantageous. There was a problem.

Means for Solving Problems The inventors of the present invention have made extensive studies to overcome these problems, and have found that glycinonitrile and ammonium bicarbonate, ammonium carbonate, ammonia and carbon dioxide, or a mixture thereof. The present inventors have discovered that when a sulfite or an acidic sulfite is present when reacting the reaction mixture in water or an aqueous solvent, coloring of the reaction solution can be significantly prevented, and the present invention has been completed.

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, and acidic sulfite. Potash is preferred. Alternatively, sulfur dioxide gas may be directly blown into the solution before the reaction to generate ammonium sulfite or acidic ammonium sulfite, but there is no particular difference in effectiveness regardless of which method is used. 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 0.001 to 0 per mol of glycinonitrile as the reaction raw material.
．． 3 mol, preferably 0. It may be 0.05 mol from Ol.

2. Examples Next, typical examples of the method of the present invention will be shown and explained in more detail, but these are merely illustrative examples, and therefore the present invention is not limited in any way by these examples. do not have.

Example 1 28.0 g (0.5 mol) of glycinonitrile and 84.8 g (1.1 mol) of heavy acid ammonium are added to 200 g of 15% aqueous ammonia. In addition, sodium sulfite 1.4
Hydantoin 32.3g (0,011 mol) was added and reacted at 75°C for 6 hours. From liquid chromatographic analysis of the reaction solution, hydantoin 32.
5%, hydantoin@7.7%, and hydantoic acid amide 42.2%. Further, the absorbance (-1 ogt) of the reaction solution at wavelength 4GOr+w was 8.41.

Example 2 Approximately 250 ml of water was heated to 55°C and gassed with ammonia and carbon dioxide, resulting in ammonia 16.
7% carbon dioxide and 273 g of a 17.3% carbon dioxide solution were 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. . The yield was 28.5% hydantoin, 10.1% hydantoic acid, and 43.0% hydantoic acid amide. Moreover, the absorbance of the reaction solution was 3.1.

Example 3 28.0 g (0.5 mol) of glycinonitrile and 94.2 g (1.1 mol) of ammonium carbonate are added to 188 g of 5% aqueous ammonia. In addition, acidic potassium sulfite 13.2
g (0.11 mol) was added and reacted at 75°C for 6 hours. Hydantoin 20.6%, hydantoic acid 5.7
%, the yield of hydantoic acid amide was 28.1%.

In addition, the absorbance of the reaction solution at a wavelength of 400 nm is 1.8
It was 8.

Comparative Example 1 27.8 g (0.5 mol) of glycinonitrile and 85.1 g (1.1 mol) of ammonium bicarbonate are added to 200 g of 15% aqueous ammonia and reacted 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%, Hydantoic acid amide 43.
The yield was 3%. Further, the absorbance of the reaction solution at a wavelength of 400 nm was 16.75.

Claims (1)

[Claims] Glycinonitrile in water or aqueous solution ammonium bicarbonate, ammonium carbonate or is ammonia and carbon dioxide or these to produce hydantoin by reacting with the mixture. Do not use sulfites or acid sulfites when Coloring of a reaction solution characterized by the presence of How to prevent it.