JPS6039267B2 - How to stabilize glycinonitrile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stabilizing glycinonitrile, which is characterized in that it is brought into contact with an alkali metal sulfite or acid sulfite.

Glycinonitrile is a substance useful as an intermediate for the synthesis of glycine, which is useful as a food and feed additive, as well as a synthetic raw material for medicines, agricultural chemicals, etc. Although it is easily obtained by reacting with ammonia, it is very unstable, and if left alone, it will become colored in a short time even at room temperature, turning brown to blackish brown.

Therefore, it is difficult to store and transport, and despite its usefulness, it is rarely sold in its original form as a general commodity. The inventors of the present invention have investigated various methods for preventing coloration and deterioration of glycinonitrile and making it possible to store and transport the product.The inventors have found that the method involves bringing glycinonitrile into contact with an alkali metal sulfite or an acidic sulfite at room temperature. It was discovered that the intended purpose could be achieved by

As the alkali metal sulfite or acid sulfite to be used in the method of the present invention, sodium sulfite, potassium sulfite, acidic sodium sulfite, acidic potassium sulfite, etc. are preferable, and there is no particular difference in effectiveness regardless of which one is used. Contact with glycinonitrile is quite effective even if a small amount of sulfite or acid sulfite is added to the solution, but it is also possible to make contact with glycinonitrile by filling a column with granular sulfite or acid sulfite. A more pronounced effect is observed when glycinonitrile is passed through the inside. In this case, the rate at which glycinonitrile passes through the column is not necessarily limited, but the SV is practically 0.
A sufficient effect can be obtained with a degree of 5 to 1. Hereinafter, typical examples of the method of the present invention will be shown and more specifically explained, but these are merely illustrative, and it goes without saying that the present invention is not limited by these examples in any way.

Example 1 A 50% aqueous solution of glycolonitrile and liquid ammonia,
40℃ with glycolonitrile/ammonia molar ratio 1/6
After flashing ammonia, the reaction product solution obtained by reacting in an autoclave for 1 hour was distilled under reduced pressure to obtain a colorless and transparent 90% aqueous glycinonitrile solution (stock solution).

A portion of this liquid was placed in a flask, and 0.5% of powdered sodium sulfite was added to it, and after the air inside was replaced with nitrogen gas, it was tightly capped and left in a storage room at room temperature (Sample 1). . Separately, a glass shielded with aluminum foil with an inner diameter of 1.5 mm and a height of 30 mm was filled with 10% of fine particles of sodium sulfite, and the above glycinonitrile stock solution was passed through it at a speed of SV2 and collected into a flask. After replacing the air inside with nitrogen gas in the same manner as above, the container was sealed tightly and left at room temperature in a room (Sample 2).

After a certain period of time, a photoelectric spectrometer (using a quartz cell)
The absorption in the visible region of each sample was measured (measurement range, wavelength: 600 to 30 m), and the change in temperature was determined.

The chart is shown in the figure, where A is for the stock solution (sealed with N2, sealed and left at room temperature in a refrigerator), B is for sample 1, and C is for sample 2. As is clear from this chart, in addition to the overall increase in absorption in the undiluted solution, it is also observed that the absorption with a peak around 38 m becomes larger over time, whereas in sample 1, the overall absorption increases over time. There is little absorption in the area, and the absorption in the vicinity of 38 meters is also not large.

Furthermore, in sample 2, remarkable effects such as almost no absorption in the vicinity of the peak m and a small overall absorption are observed. In addition, we conducted the same tests as above by varying the amount of sodium sulfite added and the SV during column passage, and the absorbance at a wavelength of 38 m (100 m) was determined. The results are shown in Table 1. show.

Table 1 Note that during the two-day test, no decrease in the purity of glycinonitrile was observed in any of the samples except for the stock solution.

Example 2 90% glycinonitrile obtained in the same manner as Example 1
1. Add potassium sulfite or acidic sodium sulfite or a mixture thereof to the aqueous solution. After adding t% of skin to the tube and replacing the internal air with nitrogen gas, it was left in a closed room at room temperature.

Two days later, the absorbance (1 log) at a wavelength of 38 m was determined.

The results are shown in Table-2. 2

[Brief explanation of the drawing]

The drawings show the results of Example 1, with the vertical axis representing absorbance and the horizontal axis representing wavelength. (A) (B) <C)

Claims (1)

[Claims] 1. A method for stabilizing glycinonitrile, which comprises bringing glycinonitrile into contact with an alkali metal sulfite or acid sulfite.