JPH02169578A - Production of hydantoin - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing 5-phenylhydantoin without producing oily substances or the like in a method for producing hydantoin.

5-Phenylhydantoin is an important intermediate raw material for the production of phenylglycine, which is used as a modifier for agricultural chemicals and antibiotics.

[Conventional technology]

The production method for hydantoins itself is based on Buffellerbergs (
This method has long been known as the Bucherer-Bergs method, in which cyanohydrin is reacted with carbon dioxide and ammonia.

[Invention tries to solve it! Therefore, the present inventors attempted to produce 5-phenylhydantoin by reacting benzaldehyde cyanohydrin (hereinafter abbreviated as BCH) with carbon dioxide and ammonia. However, this method has the following problems.

When producing BCH from benzaldehyde (hereinafter abbreviated as BAD) and hydrogen cyanide in a one-ship method, it is difficult to completely react the raw material BAD by an equilibrium reaction. When this BCH solution containing unreacted BAD is charged with carbon dioxide and ammonia in a container equipped with a stirring device and reacted, a reddish-brown oily substance appears from the early stage of the reaction. Since this oily substance is sticky, it adheres to the stirrer and the inner wall of the reactor and is very difficult to remove.

In particular, if it becomes entangled with the agitator 81 blades, the agitator shaft will become eccentric and vibrate, causing damage to the agitator, etc., which is a very dangerous problem for scaled-up industrial scale equipment. It's Uruchino. Furthermore, as a matter of course, the yield of 5-phenylhydantoin decreases by the amount of oily substances generated.

Therefore, conventionally, water-soluble organic solvents such as alcohol are used.
The formation of oily substances has been prevented by carrying out the reaction homogeneously or by adding a surfactant or conducting the reaction in an emulsified state by strong physical stirring. However, from an industrial standpoint, the combined use of organic solvents requires a recovery process, which not only complicates the process, but also inevitably increases costs such as energy costs. Further, the addition of a surfactant may cause severe foaming or bumping when excess ammonia and carbon dioxide are concentrated and recovered after the reaction is completed. In addition, when it comes to strong physical stirring, it is unavoidable that costs will increase significantly if the equipment is manufactured on an industrial scale, such as purchasing a stirrer that requires a large amount of power and strengthening the pedestal to support it. [Means and effects for solving the problem] Therefore, the present inventors carefully investigated the causes of oily substance formation, and found that one of the causes was unreacted raw materials contained in BCII Qa, and that the decomposition of BCH By pre-existing hydrogen cyanide or its salts in excess of the BAD in the BC solution and carrying out the hydantoinization reaction, it is possible to prevent the production of oily substances and to prevent the reaction. The present invention was completed based on the good results that the yield was improved.

That is, the present invention provides a method for producing 5-phenylhydantoin by reacting BC)l with carbon dioxide and ammonia, in which hydrogen cyanide or a salt thereof in excess of BAD remaining in the BCl solution is reacted. This is a method for producing 5° phenylhydantoin, which is characterized in that it is present in the system in advance.

The excess amount of hydrogen cyanide or its salts is a molar excess of BAD contained in the BC solution, preferably 1.1 to 2
．． It is sufficient if it is 0 times the molar amount.

As for the upper limit of the amount added, there is no particular limit, but if you add too much than necessary, it may cause coloring due to hydrogen cyanide polymerization, etc., and a hydrogen cyanide recovery process may be required later.
It is desirable to use the minimum amount necessary to meet the conditions.

Examples of the hydrogen cyanide salts used include sodium cyanide, potassium cyanide, and ammonium cyanide.

Next, carbon dioxide and ammonia sources may be those commonly used. Further, carbon dioxide and ammonia, ammonium carbonate, or ammonium bicarbonate are used in excess of the stoichiometric amount, preferably 1 to 4 times the amount of BCH.

The reaction temperature may be 50 to 150° C. and the reaction time may be 0° C. for 25 to 6 hours.

〔Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, the analysis of 5-phenylhydantoin and its by-products in Examples is based on high performance liquid chromatography.

Example 1 Glass inner volume 1i with stirring device! 70.6 g of ammonium bicarbonate in an autoclave of 24.9
Weight% ammonia aqueous solution 9.4 g, water 515 g and 3
2.4% by weight sodium cyanide aqueous solution 5.0g (0,
033 mol) and heated to 100°C under recirculation conditions. To this, 75.0 g of BC) I liquid (BCH0,49
8 mol, hydrogen cyanide 0.0001 mol, BAD O,
028 mol) was continuously added over 2.0 hours to carry out the reaction. The molar ratio of hydrogen cyanide and charged sodium cyanide to BAD (0,028 mol) in the BCH solution in the 5-phenylhydantoin reaction system was 1.18.

A post-reaction was further performed for 1 hour to complete the reaction. When the product in the reaction solution was analyzed, the production rate based on (BCH+BAD) was 83.2 mol% of 5-phenylhydantoin, N
~Carbamoylphenylglycine 7.2 mol%, N-carbamoylphenylglycinamide 4.1 mol%, phenylglycine 361 mol%, total production rate 97.6
It was mol%.

In addition, from the initial stage of BCHC hot liquid to the end of the reaction,
No formation of oily substances was observed.

Next, the reaction solution was concentrated under reduced pressure to remove excess ammonia and carbon dioxide, and then sulfuric acid was added to make the sulfuric acid concentration 5% by weight.
After the completion of the ring opening and closing reaction at °C for 3 hours, the products in the reaction solution were analyzed and the production rate based on (BCH+BAD) was 92.0 mol% of 5-phenylhydantoin and 3.3 mol of phenylglycine. %, and the total production rate is 95.3
It was mol%.

Example 2 32.4% by weight sodium cyanide aqueous solution 5.0g (0
The same operation as in Example 1 was carried out, except that 9.0 g (0,034 mol) of a 10.2% by weight aqueous hydrogen cyanide solution was added instead of 10.2% by weight aqueous hydrogen cyanide solution (0,033 mol).

BAD in BCH solution in 5-phenylhydantoin reaction system
(0,028 mol) to hydrogen cyanide (0,000
1 mol) and charged hydrogen cyanide (0,034 mol)
The molar ratio of was 1.22.

After the reaction was completed, the product in the reaction solution was analyzed, and it was found that (B
The generation rate of CH+BAD) standard is 5. The contents were 83.5 mol% phenylhydantoin, 7.2 mol% N-carbamoylphenylglycine, 4.3 mol% N-carbamoylphenylglycinamide, and 2.9 mol% phenylglycine.

In addition, from the initial stage of BCHC hot liquid to the end of the reaction,
No formation of oily substances was observed.

Next, the reaction solution was compressed under reduced pressure to remove excess ammonia and carbon dioxide, and then sulfuric acid was added to make the sulfuric acid concentration 5% by weight.
After the ring-closing reaction was carried out at °C for 3 hours, the product in the reaction solution was analyzed and the production rate based on (BCH+BAD) was 92° of 5-phenylhydantoin.

4 mol%, phenylglycine 3.1 mol%, and the total production rate was 95.5 mol%.

Comparative Example I The same operation as in Example 1 was carried out except that the composition of the BCH liquid was changed, and as a result, the production of an oily substance was observed in L2 from around 5 hours after the addition of the hot BCHC liquid. Used here
CH solution 75: Og(BC)I O, 498 mol, hydrogen cyanide 0.0001 mol/L, BAD O, 028 mol) 17) The molar ratio of hydrogen cyanide to BAD is 0.
．． 004 and was in a shortage state. After the reaction was completed, the product in the reaction solution was analyzed, and the production rate based on (BCH+BAD) was 5. Phenylhydantoin 79.1 mol%, N-
Carbamoylphenylhydantoin 6.7 mol%, N-
Carbamoylphenylglycinamide was 4.1 mol%, phenylglycine was 2.7 mol%, and the total production rate was 92.
It was 6 mol%.

Next, the reaction solution was concentrated under reduced pressure to remove excess ammonia and carbon dioxide, and then sulfuric acid was added to give 5% by weight of acid'a.
A ring-closing reaction was carried out at 5°C for 3 hours. After the reaction was completed, the product in the reaction solution was analyzed (BCH+BAD).The standard production rate was 5-7 enylhydantoin 87°4 mol%.
Phenylglycine is 2.9 mol%, and the total production rate is 90
．． It was 3 mol%.

[Effects of the Invention] The advantages brought about by the present invention are as follows.

By previously adding hydrogen cyanide or its salts in excess of BAD in the BCH solution to the BCII solution and performing the hydantoinization reaction, BAD also participates in the reaction and the yield is improved. In addition, it is possible to prevent the production of oily substances, which are BADO polymer compounds.

The degree of yield improvement varies depending on the reaction conditions and the proportion of BAD in the BC1 solution.

That is, by the method of the present invention, 5-phenylhydantoin can be obtained without producing oily substances that improve the yield.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] (1) In a method for producing 5-phenylhydantoin by reacting benzaldehyde cyanohydrin with carbon dioxide and ammonia, hydrogen cyanide or its salts in excess of the benzaldehyde remaining in the benzaldehyde cyanohydrin solution is reacted. A method for producing 5-phenylhydantoin, the method comprising making it exist in a system in advance.