JPH06239838A - Method for recovering hydantoins - Google Patents

Abstract

PURPOSE:To provide a method for recovering hydantoins by which the hydantoins dissolved in a mineral acid and/or a solution of a mineral acid salt can be recovered at a high recovery ratio and the recovery can repetitively and continuously be carried out without performing regenerating operation at all. CONSTITUTION:This method for recovering hydantoins is characterized by bringing a solution of the hydantoins containing >=5wt.% mineral acid salt into contact with an ion exchange resin at a pH of the solution within the range of 2-10, adsorbing the hydantoins thereon and then releasing the adsorbed hydantoins with an eluent. The method is suitable for recovering the hydantoins dissolved in a mother liquor or a filtrate after separating the various hydantoins in production thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently recovering hydantoins contained in a filtrate or a mother liquor after separating hydantoins crystals. Hydantoins are useful as intermediate raw materials for α-amino acids or as intermediate raw materials for agricultural chemicals, pharmaceuticals, and food additives.

[0002]

2. Description of the Related Art In order to obtain hydantoins, various production methods have hitherto been known. For example, hydantoins are
After reacting hydrocyanic acid, a carbonyl compound, ammonia, and carbon dioxide to obtain a mixed solution containing hydantoin, hydantoic acid, hydantoinamide, and the like, next, the hydantoinic acid and hydantoinamide are closed with a mineral acid, and the solution is obtained. It can be obtained by separating more crystals.

Further, as a method for producing the hydantoins other than the above, for example, in the presence of a palladium-carbon catalyst, 5
There is a method in which arylidene hydantoin is reduced with hydrogen in an alkaline aqueous solution to obtain a solution containing hydantoins, and then neutralized with a mineral acid to separate and obtain the precipitated crystals (Japanese Patent Laid-Open No. 2004-187242). 63-17864).

As described above, hydantoins are usually obtained by separating precipitated crystals. The filtrate or mother liquor discharged at that time (hereinafter referred to as mother liquor) is generally a mineral acid and / or a mineral acid salt solution, in which hydantoins which cannot be separated above are usually It is contained at about 0.1 to 10% by weight. It is a great loss to discharge expensive hydantoins out of the system as they are, and since this mother liquor increases the BOD of wastewater,
It also costs extra to process. Therefore, it is necessary to collect hydantoins dissolved in the mother liquor as much as possible.

Incidentally, as a means for recovering a specific substance from the mother liquor as described above, for example, a recovery method of adsorbing the target substance with activated carbon and then desorbing it can be considered.

[0006]

However, in the above method of adsorption and desorption by using activated carbon, particularly when the target substance is hydantoins in the mother liquor, adsorption to activated carbon is achieved to some extent. There is a problem that the adsorbed hydantoins are very difficult to desorb, and the recovery rate is only about 5% at best. In addition, even if hydantoins are recovered by this method, if the used activated carbon is to be used repeatedly, equipment for regenerating the activated carbon is required in addition to this recovery operation. Since a large amount of such items are required, the cost is high. Therefore, it is not preferable for repeatedly and continuously recovering hydantoins.

Therefore, in the present invention, when the hydantoins are recovered from the mineral acid and / or mineral acid salt solution which is the mother liquor after separating the crystals of the hydantoins, an easy and repeated continuous operation is possible, and It is an object of the present invention to provide a method of recovering a high recovery rate.

[0008]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that the pH of the mother liquor after separating the hydantoin crystals is within a specific range,
Moreover, when the mineral acid salt also exceeds a specific concentration, hydantoins are efficiently adsorbed when the mother liquor is brought into contact with the ion exchange resin, and after adsorption, the hydantoins are easily desorbed by the eluent. It has been found that hydantoins can be recovered with a high recovery rate when separated. Further, they have found that the ion-exchange resin used can be used as it is for the above-mentioned adsorption / desorption operations of hydantoins without repeating any regeneration step, and thus completed the present invention.

That is, in the present invention, a hydantoin solution containing 5% by weight or more of a mineral acid salt is brought into contact with an ion exchange resin in a pH range of 2 to 10 to adsorb the hydantoins, and then the ion is adsorbed. It is a method for recovering hydantoins, which comprises desorbing hydantoins adsorbed on an exchange resin with an eluent.

The target of the treatment in the recovery method of the present invention can be a solution containing general hydantoins even if the pH and the mineral acid salt concentration are adjusted. However, what is of particular interest is the mother liquor after the crystals of hydantoins have been separated by centrifugation or filtration. And, as types of recoverable hydantoins, hydantoin, 5-methylhydantoin, 5-ethylhydantoin, 5-propylhydantoin, 5-isopropylhydantoin, 5,5-dimethylhydantoin, 5-isobutylhydantoin, 5-secondary butyl Hydantoin, 5-ethyl-5-methylhydantoin, 5-isopropyl-
5-methylhydantoin, 5- (methoxymethyl) hydantoin, 5-phenylhydantoin, 3-phenylhydantoin, 5-benzylhydantoin, 5- (4-methoxybenzyl) hydantoin, 5- (2-methylbenzyl) hydantoin, 5- (Hydroxy-3-methoxybenzyl) hydantoin, 5- (3,4-dimethoxybenzyl) hydantoin, 5-parahydroxyphenylhydantoin, 5- (4-hydroxybenzyl) hydantoin, 3- (3,5-dichlorophenyl)
Hydantoin, 5- (4-hydroxy-3-methoxyphenyl) hydantoin, 5-benzylidene hydantoin, 5-
(4-Methoxybenzylidene) hydantoin, 5- (2-methylbenzylidene) hydantoin, 5- (hydroxy-3-methoxybenzylidene) hydantoin, 5- (3,4-dimethoxybenzylidene) hydantoin, 5- (4-hydroxybenzylidene) Examples include hydantoin.

Further, according to the present invention, not only can the hydantoins produced be recovered, but for example, when 5-arylidene hydantoins are used as a raw material and various hydantoins are produced, the unreacted residual hydantoins remain in the mother liquor. Of reaction
It is also possible to collect 5-aryliden hydantoin.

In the recovery method of the present invention, the concentration of hydantoins in the solution is not particularly limited and can be within a wide range. Generally, the mother liquor after separating the hydantoin crystals usually contains about 0.1 to 10% by weight of hydantoins, but when the hydantoins are further recovered from this mother liquor, the recovery of the present invention is performed. The method is particularly preferably applicable. Further, since these mother liquors are usually treated with a mineral acid such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, etc., in general, the pH thereof is relatively strong acid of 0.1 to 0.7.

In the recovery method of the present invention, in order to efficiently adsorb hydantoins in the mother liquor to the ion exchange resin, the pH of the mother liquor is set to 2 to 10, more preferably 5 to 9, and contained therein. 5% by weight or more of
More preferably, the content is adjusted to 10% by weight or more, and the range is such that mineral salt crystals do not precipitate. Outside these ranges, ie
When the pH of the mother liquor is out of the range of 2 to 10, the adsorption efficiency of hydantoins on the ion exchange resin is significantly lowered, which is not preferable. Further, when the concentration of the mineral acid salt is less than 5% by weight, the adsorption efficiency of the hydantoins to the ion exchange resin is lowered and the recovery rate is remarkably high even if the pH is in the range of 2 to 10. It is not preferable because it becomes low.

Further, when the concentration of the mineral acid salt is increased and the mineral acid salt crystals are precipitated at a solubility or higher, the adsorption efficiency on the ion exchange resin is not affected, but the precipitated mineral acid salt is not affected. For example, ammonium sulphate, sodium sulphate, sodium chloride, etc. may block the inlet / outlet tube of the column filled with the ion exchange resin, making the adsorption operation impossible. Of course, it does not matter if the mineral acid salt is precipitated when the operation of separating the precipitated crystal in advance is added.

In order to adjust the pH of the mother liquor and the concentration of the mineral acid salt contained therein, it is usually sufficient to add an alkali to the mother liquor. Further, as the alkali used therefor, general alkalis can be widely used, and examples thereof include ammonia, sodium hydroxide and potassium hydroxide. Two or more of these may be used, or a mixture thereof may be used.

The ion exchange resin used in the recovery method of the present invention may be a weakly acidic ion exchange resin or a weakly basic ion exchange resin, but a strongly acidic cation exchange resin is preferably used. Furthermore, it is particularly preferable to use a strongly acidic cation exchange resin having a sulfone group. For example, Levatit S-100, Seva S-109, MDS1368 (above, manufactured by Bayer); Diaion SK-1B, PK
-208, PK-212, UBK-530 (Made by Mitsubishi Kasei Co., Ltd.); Dowex Monosphere, HCR-S, 50
WX1 and 50WX2 (both manufactured by Dow Chemical Co.); Amberlite IR-122 and 200C (both manufactured by Rohm and Haas Co.) are commercially available under various trade names, all of which are available. It can be used.

In the recovery method of the present invention, the strongly acidic cation exchange resin is used after being adjusted to a salt type. The type of this salt is one or two types from Li, Na, K, Ca, NH4 and the like. The above is appropriately used.

In the recovery method of the present invention, the eluent used when desorbing the hydantoins adsorbed on the ion exchange resin can be widely used as long as it is a liquid in which the hydantoins are soluble. For example, methanol, Examples thereof include common organic solvents such as ethanol, mixed solutions of organic solvent and water, or water. However, in some cases organic solvents are difficult to dissolve the mineral acid salt in the treatment liquid,
Usually, it is preferable to use water, and a high recovery rate can be obtained. In this case, any aqueous solution containing no mineral salt can be widely used, and for example, a dilute aqueous solution of hydantoins can be preferably used.

Examples of the adsorption operation in the recovery method of the present invention include a column type method in which the column is filled with an ion exchange resin and then the liquid to be treated is passed in an upward flow or a downward flow. It is also possible to use a method according to one. When using the column method, there is no particular restriction on the flow rate,
Normally, the space velocity (hereinafter referred to as SV) is 0.1 to 100.
It can be operated in a wide range of about hr ^-1 .

The elution operation for desorbing the hydantoins adsorbed on the ion exchange resin is carried out by contacting with water, an aqueous solution containing no mineral acid salt, or an organic solvent after the above-mentioned adsorption operation is completed. It can be easily eluted. Even in this case, there is no particular limitation on the liquid passing rate of the eluent, and the SV is usually 0.1 to 100.
It is possible in a wide range of about hr ^-1 .

Furthermore, the ion-exchange resin from which the hydantoins have been desorbed by the elution operation described above does not need to be subjected to any regeneration step or the like, and the recovery operation can be similarly repeated as it is. Therefore, the recovery method of the present invention can be particularly preferably applied to the case where the hydantoins dissolved therein are continuously recovered from the mother liquor discharged when the hydantoins are produced.

The temperature of the above-mentioned adsorption / elution operation in the recovery method of the present invention is not particularly limited and can be made in a wide range, but generally it is operationally preferable to carry out at a temperature at which the salt in the mother liquor does not precipitate, Can be sufficiently performed in the range of 10 to 80 ° C.

[0023]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the following, “%” is based on weight. Also,
The components in the solution were analyzed by liquid chromatography and ion chromatography.

Example 1 As a stock solution, an aqueous solution containing hydantoin 2.08%, sulfuric acid 7.50% and ammonium sulfate 2.86% and having a pH of 0.3 was used. Liquid ammonia was added dropwise to this stock solution to remove hydantoin 2.03.
% And ammonium sulfate 11.7% were used as the liquid to be treated at pH = 6. As the ion exchange resin, Dowex Monosphere 99 (manufactured by Dow Chemical Co .; trade name), which is a strongly acidic cation exchange resin, is used.
It was packed in a 160 mm glass column (with a jacket, and water having the same temperature as the temperature of the liquid to be treated flows on the jacket side). From above the column, 200 ml of the above treated liquid at 30 ° C
Was passed through at a SV of 1 hr ^-1 by a downward flow, and 200 ml of the treated liquid was obtained from the column outlet. Next, 260m water at 30 ℃ as eluent
l is passed downward from above and at SV = 1 hr ^-1 , and the initial 60 m
l was used as the treatment liquid, and 200 ml was collected as the eluent. Each concentration in 260 ml of all treated solutions was 0.28% hydantoin and 7.41% ammonium sulfate. The concentrations in the eluent were hydantoin 1.76% and ammonium sulfate 2.35%, and the recovery rate of hydantoin based on the stock solution was 82.4%. The above results are shown in Table 1.

Example 2 In Example 1, the ion exchange resin was Diaion UBK-530 (manufactured by Mitsubishi Kasei Co., Ltd.) which is a strongly acidic cation exchange resin.
The procedure was exactly the same except that the product name was changed. The results are shown in Table 1.

Example 3 As a stock solution, an aqueous solution containing 2.11% of hydantoin, 13.92% of sulfuric acid and 11.41% of ammonium sulfate and having a pH of 0.1 was used. Liquid ammonia was added dropwise to this stock solution to obtain a liquid to be treated having a pH = 6 containing 2.03% of hydantoin and 25.4% of ammonium sulfate. Hereinafter, the same operation as in Example 1 was performed using this liquid to be treated. The results are shown in Table 1.

Example 4 In Example 1, the amount of liquid ammonia added dropwise to the stock solution was changed to obtain a liquid to be treated having a pH of 3 containing 6.28% ammonium sulfate. Hereinafter, the same operation as in Example 1 was performed using this liquid to be treated. The results are shown in Table 1.

Example 5 The same procedure as in Example 1 was repeated except that the mineral acid salt in the liquid to be treated was not ammonium sulfate but sodium sulfate having the same concentration, and the other components had the same composition and pH = 6. The results are shown in Table 1.

Example 6 In Example 1, the eluent was a 0.37% aqueous hydantoin solution. Otherwise the operation was exactly the same as in Example 1. The results are shown in Table 1.

Example 7 The same operation as in Example 1 was repeated, except that the ion exchange resin after desorption of hydantoin with the eluent was used as it was. The results are shown in Table 1.

Comparative Example 1 In Example 1, activated carbon C was used instead of the ion exchange resin.
The same operation was performed except that PG (manufactured by Toyo Calgon Co., Ltd .; trade name) was used. The results are shown in Table 1.

Comparative Example 2 Hydantoin 2.08% as a liquid to be treated, ammonium sulfate
An aqueous solution of pH = 6 containing 3.85% was used. Hereinafter, the same operation as in Example 1 was performed using this liquid to be treated. The results are shown in Table 1.

Comparative Example 3 In Example 3, the stock solution was used as it was as a solution to be treated. That is, pH containing 11.41% ammonium sulfate
= 0.1 to be treated liquid. Hereinafter, the same operation as in Example 3 was performed using this liquid to be treated. The results are shown in Table 1.

[0034]

[Table 1] Note: In Table 1, H indicates hydantoin, AS indicates ammonium sulfate, and SS indicates sodium sulfate.

Example 8 An aqueous solution (pH = 7) containing 5.40% of 5,5-dimethylhydantoin and 6.62% of ammonium sulfate was used as a liquid to be treated. 80 ml of the above-mentioned liquid to be treated at 30 ° C. was passed by a downward flow at SV = 1 hr ⁻¹ from the upper side of the same column packed with the same amount of the same ion exchange resin as used in Example 1 from the column outlet. 80 ml of the treatment liquid was obtained. Next, water at 30 ° C as the eluent
260 ml was passed downward from above at SV = 1 hr ⁻¹ , the initial 60 ml was used as the treatment liquid, and 200 ml was collected as the eluent. The respective concentrations in 140 ml of the total treated solution were 0.71% of 5,5-dimethylhydantoin and 3.09% of ammonium sulfate. The concentration in the eluent was 5,5-dimethylhydantoin 1.72
%, Ammonium sulfate 0.56%, based on undiluted solution
The recovery rate of 5,5-dimethylhydantoin was 76.0%.
The above results are shown in Table 2.

Example 9 An aqueous solution (pH = 6) containing 1.10% of 5-isopropylhydantoin and 26.9% of ammonium sulfate was used as a liquid to be treated. From the upper side of a similar column packed with the same amount of the same ion exchange resin as that used in Example 1, 200 ml of the above-mentioned liquid to be treated at 30 ° C. was passed by a downward flow at SV = 1 hr ⁻¹ , and then from the column outlet. 200 ml of the treatment liquid was obtained. Then 30 as eluent
260 ml of water at 0 ° C. was passed downward from above at SV = 1 hr ⁻¹ , the initial 60 ml was used as the treatment liquid, and 200 ml was collected as the eluent. Each concentration in 260 ml of the whole treated solution was 0.10% of 5-isopropylhydantoin and 19.51% of ammonium sulfate. The concentrations in the eluent were 5-isopropylhydantoin 1.09% and ammonium sulfate 2.77%, and the recovery rate of 5-isopropylhydantoin based on the stock solution was 88.4%.
%Met. The above results are shown in Table 2.

Example 10 As a liquid to be treated, an aqueous solution containing 0.28% of 5- (4-hydroxybenzyl) hydantoin and 5.85% of sodium chloride (pH =
9) was used. From the top of a similar column packed with the same amount of the same ion exchange resin as used in Example 1 from above,
400 ml of the above-mentioned liquid to be treated was passed by a downward flow at SV = 0.5 hr ^-1 to obtain 400 ml of the treatment liquid from the column outlet. Next, 260 ml of water at 30 ° C was used as an eluent, and SV = 1 in a downward flow from above.
The solution was passed at hr ⁻¹ , the initial 60 ml was used as the treatment liquid, and 200 ml was collected as the eluent. Each concentration in 460 ml of the total treatment solution is 5-
(4-Hydroxybenzyl) hydantoin 0.05% and sodium chloride 4.62%. The concentration in the eluent is 5-
(4-Hydroxybenzyl) hydantoin was 0.45% and sodium chloride was 1.19%, and the recovery rate of 5- (4-hydroxybenzyl) hydantoin was 78.5% based on the stock solution. The above results are shown in Table 2.

Example 11 An aqueous solution (pH = 5) containing 0.25% 5-phenylhydantoin and 25.8% ammonium sulfate was used as a treatment liquid. From above the same column packed with the same amount of the same ion exchange resin as that used in Example 1, from above the treated liquid at 20 ° C. 400
ml was passed through with a downward flow at SV = 0.5 hr ^-1 , and 400 ml of the treated liquid was obtained from the column outlet. Next, water at 30 ° C as the eluent
260 ml was passed downward from above at SV = 1 hr ⁻¹ , the initial 60 ml was used as the treatment liquid, and 200 ml was collected as the eluent. Each concentration in 460 ml of the total treated liquid was 0.02% of 5-phenylhydantoin and 21.75% of ammonium sulfate. Also, the concentration in the eluent is 5-phenylhydantoin 0.50
%, Ammonium sulfate 3.0%, based on undiluted solution
The recovery rate of 5-phenylhydantoin was 90.6%. The above results are shown in Table 2.

Example 12 As a liquid to be treated, an aqueous solution (pH = 5) containing 0.27% of 5-benzylhydantoin and 24.2% of ammonium sulfate was used. 400 ml of the above-mentioned liquid to be treated at 20 ° C. was passed by a downward flow at SV = 0.5 hr ⁻¹ from above the same column filled with the same amount of the same ion exchange resin as that used in Example 1, and the column outlet As a result, 400 ml of the treatment liquid was obtained. Then 30 as eluent
260 ml of water at 0 ° C. was passed downward from above at SV = 1 hr ⁻¹ , the initial 60 ml was used as the treatment liquid, and 200 ml was collected as the eluent. The respective concentrations in 460 ml of the whole treated solution were 5-benzylhydantoin 0.02% and ammonium sulfate 20.1%.
In addition, the concentration in the eluent is 5-benzylhydantoin 0.53
%, Ammonium sulfate 3.0%, based on undiluted solution
The recovery rate of 5-benzylhydantoin was 89.0%. The above results are shown in Table 2.

[0040]

[Table 2] Note: In Table 2, H indicates various hydantoins, AS indicates ammonium sulfate, and SC indicates sodium chloride.

Example 13 As a liquid to be treated, an aqueous solution containing 0.18% of 5- (4-hydroxybenzyl) hydantoin, 0.51% of 5- (4-hydroxybenzylidene) hydantoin and 5.91% of sodium chloride (pH =
6) was used. From the top of a similar column packed with the same amount of the same ion exchange resin as used in Example 1 at 30 ° C.
200 ml of the above-mentioned liquid to be treated was passed by a downward flow at SV = 0.5 hr ⁻¹ , and 200 ml of the treatment liquid was obtained from the column outlet. Next, 260 ml of water at 30 ° C was used as an eluent, and SV = 1 in a downward flow from above.
The solution was passed at hr ⁻¹ , the initial 60 ml was used as the treatment liquid, and 200 ml was collected as the eluent. Each concentration in 260 ml of the total treatment solution is 5-
(4-hydroxybenzyl) hydantoin 0.03%, 5- (4-
Hydroxybenzylidene) hydantoin was 0.1% and sodium chloride was 3.84%. The concentration in the eluent is 5-
(4-Hydroxybenzyl) hydantoin 0.14%, 5- (4-
Hydroxybenzylidene) hydantoin 0.39%, sodium chloride 1.04%, the recovery rate of 5- (4-hydroxybenzyl) hydantoin is 76.4%, 5- (4-
Recovery rate of hydroxybenzylidene) hydantoin is 75.0
%Met.

[0042]

According to the recovery method of the present invention, mineral acid and / or
Alternatively, the hydantoins dissolved in the mineral acid salt solution can be recovered at a high recovery rate, and can be repeatedly and continuously performed without any regeneration operation. That is, in Examples 1 to 13 carried out using the recovery method of the present invention, the hydantoins in the solution were treated with 75%
It is possible to recover with a high recovery rate of ~ 91%. On the other hand, no ion exchange resin is used, or the p
In Comparative Examples 1 to 3 in which the H or mineral salt concentration is outside the present invention, the recovery rate is low at 5 to 39%. Therefore, the method for recovering hydantoins of the present invention can be suitably used for recovering hydantoins dissolved in the mother liquor after separating crystals of various hydantoins.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shohei Nozaki Mitsui Toatsu Chemical Co., Ltd. 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa

Claims (3)

[Claims] 1. A hydantoin compound solution containing 5% by weight or more of a mineral salt is contacted with an ion exchange resin in a pH range of 2 to 10 to adsorb the hydantoin compound, and then adsorbed on the ion exchange resin. A method for recovering hydantoins, characterized in that the hydantoins are eliminated with an eluent. 2. The method for recovering hydantoins according to claim 1, wherein the ion-exchange resin after desorption of hydantoins is repeatedly used for recovering hydantoins without performing a regeneration operation. 3. The method for recovering hydantoins according to claim 1, wherein the ion exchange resin is a strongly acidic cation exchange resin.