JPS60222465A - Production of hydantoin - Google Patents

Abstract

PURPOSE:N-Carbamoylglycine is treated with a strong-acid type cation exchange resin in an aqueous mineral acid of a specific concentration and a hydantoin in the pure crystal form is obtained without neutralization, the product is used as a precursor of the corresponding alpha-aminoacid. CONSTITUTION:An N-carbamoylglycine of formula I (R is H, alkyl, aryl; X is hydroxyl, amino) is subjected to the catalytic reaction in the presence of a strong-acid type cation-exchange resin such as Levacit SC-108 in an aqueous mineral acid of less than 10%, preferably 5-8wt% concentration, preferably sulfuric or hydrochloric acid solution at 70-120 deg.C, preferably 80-100 deg.C, for 0.5-10hr, preferably 2-5hr to give a corresponding hydantoin of formula II. EFFECT:The regeneration times of the ion-exchange resin are reduced and complicated operations can be eliminated and the loss of product in the regeneration is reduced. USE:Intermediate bodies for agricultural and medicinal drugs, elements forming engineering plastics frames, or the like.

Description

[Detailed description of the invention] The present invention relates to a method for producing hydantoins.

More specifically, N-carbamoylglycine mineral acids and The present invention relates to a method for producing hydantoins C represented by the general formula (II) (wherein R is the same as in the general formula (1)) by contacting with a strongly acidic cation exchange resin.

Hydantoins are widely known as precursors of α-amino acids, and in recent years have become important compounds as intermediates in agriculture and medicine and as elements forming the skeletons of many engineering plastics.

Conventionally, various methods for producing hydantoins have been published; for example, Bucherer-Ber
There is a cyanohydrin method according to formula (1), which is generally referred to as gS reaction.

1 In order to carry out the reaction of formula (1) industrially advantageously, N-carbamoylglycines, which are by-produced as intermediates in the reaction mixture, are treated with sulfuric acid to undergo ring closure to form hydantoins. (Tokuko Sho 3)
9-24807).

Conventionally, it is known that the above acid treatment is carried out at a temperature of 6o to 130°C using an inorganic acid such as hydrochloric acid, sulfuric acid, or phosphoric acid, or a strongly acidic ion exchange resin, respectively. .

Among these, when only inorganic acids are used, u, s, and P.

2, 419.530, if it is hydrochloric acid, it is 18~
For sulfuric acid, a high concentration of 24 to 98% by weight is required.

In this method of using highly concentrated acids, after acid treatment with acids such as hydrochloric acid and sulfuric acid, concentration, cooling, and treatment are performed without neutralization.
When hydantoins are obtained by crystallization and filtration, the acid concentration is high, so the equipment used must be made of high quality material such as glass lining, which is economically disadvantageous.

On the other hand, when hydantoins are obtained by acid treatment, neutralization with alkali, concentration, cooling, crystallization and r-filtration,
A large amount of alkali is required for neutralization, and the purity of the hydatoin crystals decreases due to the salts produced.
Recirculation of the liquid is not possible, resulting in a decrease in yield.

Furthermore, a method in which only a strongly acidic cation exchange resin is used for acid treatment is disclosed in JP-A-4712S 243.
In this method, the breakthrough time of the ion exchange resin is short, the regeneration frequency is high, the process is complicated, and the product loss to the liquid used for regeneration is also large.

In view of the above facts, the present inventors have conducted extensive studies and found that the cause of shortening the breakthrough time of strongly acidic cation exchange resins is the side reaction C20H2 as shown in formula (2). The present invention was achieved based on the discovery that diammonium ions are generated and this is caused by reaction with the functional groups of the cation exchange resin.

That is, the present invention provides N represented by the general formula (1)
- A method for producing hydantoins represented by the general formula (1), which comprises treating carbamoylglycines in an aqueous mineral acid solution having a concentration of 10% by weight or less in the presence of a strongly acidic cation exchange resin. .

The N-carbamoylglycine used in the method of the present invention is N-carbamoylglycine represented by the general formula (1) or a derivative thereof.

R in this general formula (1) is hydrogen, an alkyl group having 1 to 5 carbon atoms, or an aryl group, and specifically, Z such as hydrogen; methyl, ethyl, propyl, isopropyl, secondary butyl, isobutyl, benzyl and unsubstituted or substituted phenyl groups such as phenyl and parahydroxyphenyl. Moreover, X is a hydroxyl group or an amine group.

The raw materials to be used may not only be used alone, but also a mixture of a compound in which X is a hydroxyl group and a compound in which X is an amine group, as long as R is the same in the general formula (1).

Furthermore, these N-carbamoylglycines may be supplied as a mixed solution with hydantoins.

That is, in the case of the cyanohydrin method of the above formula (1), N-carbamoylglycines are obtained as a by-product and as a mixed product with the main product hydantoins, so the method of the present invention can be continued using this as a raw material. Applicable.

In addition to the above-mentioned cyanohydrin method, the raw material N-carbamoylglycine can be prepared by, for example, the methods represented by formulas (6) and (4) (J, org', chem, Vol. 3B
, A8.

1973, p. 1527-1534).

H2 H2NH2 The mineral acids used in the method of the present invention include commonly used strong acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, with sulfuric acid and hydrochloric acid being preferred in view of economic efficiency.

In the method of the present invention, the mineral acid concentration is usually 10% by weight or less, preferably 2 to 10% by weight, more preferably 5 to 10% by weight.
It is 8% by weight.

If the mineral acid concentration exceeds 100% by weight, acid treatment will proceed even without using a cation exchange resin, but on the other hand, if the acid treatment reaction solution is neutralized with an alkali and then concentrated, cooled, crystallized and filtrated. , the amount of salt produced increases, resulting in a decrease in crystal purity and f
This is not preferable because it causes problems such as the inability to recirculate the liquid.

As the strongly acidic cation exchange resin used in the method of the present invention, any commercially available resins may be used.

Examples include Diaion 5K-IB (trade name, manufactured by Mitsubishi Kasei Corporation), Revachit 5C-108 (trade name, manufactured by Bayer Corporation), Amberlite 2000 (trade name, manufactured by Organo Corporation), and the like.

These strongly acidic cation exchange resins are used in an amount of 0.5 to 5 equivalents, preferably 1 to 2 equivalents, based on the raw material N-carbamoylglycine.

Therefore, when the reaction mixture obtained by the cyanohydrin method is subsequently treated, an amount corresponding to the coexisting ammonia etc. is further added.

In the method of the present invention, the treatment of N-carbamoylglycines in an aqueous mineral acid solution in the presence of a strongly acidic cation exchange resin is performed using an aqueous mineral acid solution containing N-carbamoylglycines and a strongly acidic cation exchange resin at the above concentration. is stirred at a predetermined temperature to bring the N-carbamoylglycines into contact with the mineral acid and the strongly acidic cation exchange resin.

The contact temperature is usually 70 to 120°C, preferably 8°C.
The temperature is 0 to 100°C.

The contact time varies depending on the type and concentration of the acid used, the amount of the strongly acidic ion exchange resin, and the contact temperature, but is usually 0.5 to 10 hours, preferably 2 to 5 hours.

The hydantoins represented by the general formula (II) obtained by the method of the present invention include hydantoin, 5-methylhydantoin, 5-ethylhydantoin, 5-propylhydantoin, 5-inbutylhydantoin, 5-secondarybutylhydantoin, - inbutylhydantoin, 5
-phenylhydantoin, 5-benzylhydantoin,
Examples include 5-barahydroxyphenylhydantoin.

According to the method of the present invention, the concentration of the mineral acid used is lower than that of the conventional method, and highly pure hydantoin crystals can be obtained with less contamination by inorganic salts when the product is taken out after neutralization. In addition, the frequency of regeneration of the ion exchange resin is reduced, complexity is eliminated, and product loss to the liquid used for regeneration is reduced.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Glycoronitrile, carbon dioxide gas, and ammonia were charged in a molar ratio of 1:3:4, and the mixture was heated at 100°C under sealed conditions.
After the reaction was completed, the mixture was concentrated to half its volume under reduced pressure at 70°C.

The composition of the obtained liquid was 27% by weight of hydantoin, 16% by weight of N-carbamoylglycinamide, and 0.0% by weight of ammonia.
It was 6% by weight.

Next, N-carbamoylglycinamide and ammonia in the reaction solution were neutralized, and sulfuric acid was added so that the sulfuric acid concentration after neutralization was 5% by weight, and the total amount of N-carbamoylglycinamide and ammonia was An equivalent amount of cation exchange resin Revatit 108 was used.

That is, 2.9 f of 98-thiosulfuric acid was added to the reaction solution 502, and further 57WLe Ruhachinoto 5C-108 was added.
The mixture was stirred at 95°C for 1 hour. After this treatment, hot filtration was performed to recover the ion exchange resin. The results are shown in Table 1 as a relationship between the number of times the recovered ion exchange resin was reused and the conversion rate.

The exchange rate was determined as follows.

Comparative Example 1 In Example 1, the acid treatment was carried out using only an aqueous sulfuric acid solution having a concentration of 5% by weight without using a cation exchange resin.

The results are shown in Table 1.

Comparative Example 2 In Example 1, the acid treatment was carried out using only a cation exchange resin without using sulfuric acid. The results are shown in Table 1.

Example 2 Isobutyraldehyde cyanohydrin, carbon dioxide gas and ammonia were charged in a molar ratio of 1:1.1:t1 and reacted at 100°C for 2 hours under sealed conditions.
After the reaction, the mixture was concentrated to half its volume under reduced pressure at 80° C. to obtain a liquid having the composition shown in Table 1, and then acid treatment was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 3 Benzaldehyde cyanohydrin, carbon dioxide gas and ammonia were added in a molar ratio of 1 to 15% by weight methanol aqueous solution.
: 1. s: 1. The mixture was charged at a ratio of 1.5 s and reacted at 80° C. for 6 hours under sealed conditions. After the reaction, the mixture was concentrated to half the volume while reducing pressure at 70° C. to obtain a liquid having the composition shown in Table 1.
Then, acid treatment was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 4 Glycolonitrile, carbon dioxide, and ammonia in a molar ratio of 1
: 4:4 ratio and reacted for 2 hours at 100°C under sealed condition. After the reaction, concentrated to half the volume under reduced pressure at 100°C to obtain a solution having the composition shown in Table 1. The sulfuric acid concentration was set to 8% by weight, and acid treatment was further carried out in the same manner as in Example 1. The results are shown in Table 1.

Example 5 18.7ft of glycine, 24L of potassium isocyanate? is dissolved in 150 WLl of water and reacted at 70° C. for 1 hour with stirring. After the reaction, the volume was concentrated to half under reduced pressure at 60°C to obtain a solution having the composition shown in Table 1. Then, hydrochloric acid was added so that the hydrochloric acid concentration was 10% by weight, and the cation exchange resin Revatit 5C-108 was added. brought into contact.

That is, 21.72 f of concentrated hydrochloric acid is added to the reaction solution 501. Further, 50 mg of Levatino) S (1!-108) was added, stirred at 95°C for 1 hour, and acid treated. After the acid treatment, hot p-filtration was performed to recover the ion exchange resin and it was reused. The results are shown in Table 1.

Claims (1)

[Claims] Shun N-carbamoyl represented by general formula (1) (1) (wherein R represents a hydrogen atom, an alkyl group or an aryl group, and X represents a hydroxyl group or an amine group) Glycine [- is treated in an aqueous mineral acid solution with a concentration of 10% by weight or less in the presence of a strongly acidic cation exchange resin, with the general formula (Il) NH, RIH (wherein R is the general formula A method for producing a hydantoin represented by (same as in case (1)).