JPS62267257A - Production of glycolonitrile - Google Patents

Abstract

PURPOSE:To obtain a compound useful as a synthetic intermediate for hydantoins in high purity and yield while suppressing formation of by-products and preventing coloring, by adding prussic acid to a formalin solution containing dissolved sodium acetate, carrying out at a specific pH value and removing the prussic acid. CONSTITUTION:Crystals or an aqueous solution of sodium acetate is added to formalin and dissolved therein to give a formalin solution and prussic acid kept at a temperature within the range of 15-30 deg.C is then added thereto. Since the pH of the reaction solution varies with the addition of the prussic acid, acetic acid or sodium acetate is added, as necessary, to keep the pH of the reaction solution at 4.8-6.0 and carry out the reaction. The pH of the reaction solution is then adjusted to <=2, preferably 1.5 with sulfuric acid to remove the residual prussic acid at <=50 deg.C under reduced pressure to afford the aimed substance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improved method for producing glycolonitrile.

Glycolonitrile is a compound useful as an intermediate in the production of hydantoins.

(Prior Art) A general method for producing glycolonitrile by reacting formalin with hydrocyanic acid in the presence of a basic catalyst is already well known.

However, these known methods are still unsatisfactory in suppressing the formation of by-products, preventing coloring of the target product, and producing high-purity products in high yields.

(Problems to be Solved by the Invention) The object of the present invention is to solve the problems of the prior art, proceed with the reaction while suppressing the production of by-products, and produce highly pure glycolonitrile without coloring. It is an object of the present invention to provide a method for producing with high yield.

(Means for Solving the Problems) The present inventors have conducted extensive studies to solve the above problems. As a result, in order to solve the above problem, it was found that it is extremely important to select conditions under which formalin, hydrocyanic acid, and glycolonitrile are stably maintained and the reaction proceeds smoothly.

In other words, it was discovered that the above problems could be solved by strictly controlling the pi of the reaction solution during the reaction, the reaction temperature, the pi of the reaction solution after the reaction, the post-treatment conditions of the reaction solution, the storage conditions of the product, etc. , completed the invention.

That is, in the present invention, approximately equimolar hydrocyanic acid is added to a formalin solution in which a catalytic amount of sodium acetate is dissolved at a liquid temperature of 15 to 30°C.
Then, if necessary, add acetic acid or sodium acetate while keeping pt+ at 4.8 to 6.0, add dropwise and react under the same conditions, and then adjust the pn of the reaction solution to 2 or less with sulfuric acid. , followed by removing residual hydrocyanic acid at 50° C. or lower under reduced pressure.

In the method of the present invention, the formalin solution in which a catalytic amount of sodium acetate is dissolved is one in which sodium acetate crystals or an aqueous solution of sodium acetate are added to formalin to dissolve sodium acetate in formalin.

Here, the formalin used in the present invention is not particularly limited, and examples thereof include commercially available formalin and paraformaldehyde dissolved in water.

A catalytic amount of sodium acetate may be dissolved in such a formalin solution. Usually, it is in the range of 0.005-%, preferably in the range of 0.01-1%.

The amount of hydrocyanic acid added to the formalin solution in which sodium acetate is dissolved may be about 1.0 to 1.05 times the mole of formalin.

It is necessary to maintain the addition temperature of hydrocyanic acid in the range of 15 to 30°C. If it is below 15°C, the reaction rate with formalin will be slow, and there is a risk that hydrocyanic acid accumulated in the reaction system will react all at once, making it difficult to control. Moreover, if the temperature exceeds 30° C., the pH of the reaction solution will gradually increase, and the generated glycolonitrile may decompose and cause coloring.

During the dropping of hydrocyanic acid, the pl+ of the formalin solution was set at 4.8 to 6.
Keep it at 0. As the reaction progresses with the dropwise addition of hydrocyanic acid, the pi of the reaction solution changes, so if necessary, acetic acid or sodium acetate is added to adjust the pl+ of the reaction solution to 4.8 to 6.
It is preferable to drop hydrocyanic acid and carry out the reaction while maintaining the temperature at 0. If the pn of the reaction solution is too low, the reaction rate will be slow, and if it is too high, a polymerization reaction may occur and the product may become colored one color.

The influence of the reaction time is small if the reaction conditions are sufficiently controlled. It may be determined as appropriate depending on the completion of the reaction.

After the reaction is completed, the pl+ of the reaction solution is adjusted to 2 or less, preferably about 1.5 using an acid. This adjustment is usually preferably carried out with sulfuric acid.

After the adjustment, hydrocyanic acid remaining in the reaction solution is then removed under reduced pressure at a temperature of 50° C. or lower.

At this time, if the temperature of the reaction solution exceeds 50°C, there is a risk that glycolonitrile will be decomposed.

The removed hydrocyanic acid can be absorbed into a formalin solution and used in the next production of glycolonitrile.

Glycolonitrile is obtained as described above.

The obtained glycolonitrile can be stably stored at 20° C. or lower in the form of an aqueous solution with a p) of about 11.5.

(Effects) According to the method of the present invention, it is possible to produce highly pure glycolonitrile almost quantitatively.

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

Example 1 1100g of 37% by weight formalin solution with 0 sodium acetate
．． After dissolving 8g in 4ml of water and adding it, the liquid temperature was 15℃,
p114. ．． 98% by weight hydrocyanic acid 37
4 g was added and the reaction was carried out under the same conditions for 12 hours.

After the reaction, the pH was adjusted to 1.5 with 25% sulfuric acid 3.78,
Then, residual hydrocyanic acid was removed at 50° C. and 50 mmHg.

The reaction solution from which hydrocyanic acid was removed was 1475 g of a colorless and transparent aqueous solution containing 51.4% by weight of glycolonitrile, and the yield of glycolonitrile based on formaldehyde was 98%.
Met.

Note that the removed hydrocyanic acid could be used in the subsequent production of glycolonitrile without any problem.

Example 2 591 g of water in 509 g of 87% by weight paraformaldehyde
, add 1.5 g of sodium acetate, and after dissolving, reduce the liquid temperature to 25°.
C1 Maintain pH 4.8-5.8, add 98 wt% hydrocyanic acid 37
4 g was added and the reaction was carried out under the same conditions for 5 hours.

After the reaction, the pH was adjusted to 1.5 with 4.0 g of 25% sulfuric acid,
Then, residual hydrocyanic acid was removed at 50° C. and 50 mmHg.

The reaction solution from which hydrocyanic acid was removed was 1470 g of a colorless and transparent aqueous solution containing 51.6% by weight of glycolonitrile, and the yield of glycolonitrile based on formaldehyde was 98%.
Met.

Comparative Example 1 1100 g of 37% by weight formalin and 0.0 g of sodium acetate.
After dissolving 8g in 4ml of water and adding it, the liquid temperature was 40℃ and the pH was
While maintaining the temperature at 5.5, dropwise addition of 98% by weight hydrocyanic acid was started.

During the dropwise addition, the reaction solution turned black and decomposed due to a sudden rise in temperature.

Comparative Example 2 5IIll of 2N aqueous sodium hydroxide solution was added to 1100g of 37% by weight formalin, and 374g of 98% by weight hydrocyanic acid was added at a liquid temperature of 15°C, and the reaction was carried out under the same conditions for 12 hours.

During this time, the pH was 9.4 to 7.0, and the reaction solution was colored yellow. The yield of glycolonitrile based on formaldehyde was 96%.

Comparative Example 3 A reaction with hydrocyanic acid was carried out in exactly the same manner as in Example 1, and 25% by weight
The pn was adjusted to 1.5 with sulfuric acid.

Then, when removal of residual hydrocyanic acid was started at 70° C. and 150 mmHg, the reaction solution turned black and decomposed.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd. Procedural master's letter (spontaneous) March 30, 1986

Claims (1)

[Claims] (1) Hydrocyanic acid is added dropwise to a formalin solution containing a catalytic amount of sodium acetate at a temperature of 15 to 30°C, and if necessary, adding acetic acid or sodium acetate while maintaining the pH at 4.8 to 6.0. A method for producing glycolonitrile, which comprises carrying out the reaction under the same conditions, adjusting the pH of the reaction solution to 2 or less with sulfuric acid, and then removing residual hydrocyanic acid at 50°C or less under reduced pressure.