KR20190094030A - Method for preparing imide compounds - Google Patents

Abstract

The present invention relates to a method for recycling N-substituted maleimide washing water and a method for manufacturing N-substituted maleimide using the same. Specifically, by adding and isomerizing a catalyst capable of isomerizing maleic anhydride or maleic acid present in the N-substituted maleimide washing waste water with fumaric acid, the washing waste water is regenerated and recycled, thereby being able to reduce additional wastewater treatment facilities and costs for maintaining the same unlike in the prior art.

Description

Method for producing imide compound {METHOD FOR PREPARING IMIDE COMPOUNDS}

The present invention relates to a method for recycling N-substituted maleimide wash water and a method for preparing N-substituted maleimide using the same.

The maleimide compound is a compound useful as a raw material for water support materials, medicines, and pesticides, and in particular, styrene resins such as ABS resins, AS resins, AB resins, ACS resins, AES resins, AAS resins, and polyvinyl chloride resins. In order to improve heat resistance of polymethyl methacrylate resin, phenol resin, and the like, it is frequently used as one of copolymerization components. Among them, N-phenyl maleimide (hereinafter also referred to as PMI) is excellent in terms of reactivity and heat resistance, and is particularly widely used.

About the manufacturing method of a maleimide compound, 1) The method obtained by dehydrating maleic anhydride and a primary amine in one step, 2) The maleamic acid is produced | generated from maleic anhydride and a primary amine, and this malea Many methods are known conventionally, such as the method of obtaining by ring-closure imidation reaction of a hydrochloric acid, and the method of obtaining by the ring-ring imidation reaction of the corresponding maleic acid monoester.

Among these methods, in 1) the method of obtaining in one step from maleic anhydride and a primary amine, there is still a problem that productivity is low because of a low yield, and 3) a ring-ring imidation reaction in the method obtained from a maleamic acid monoester. There is a problem that the alcohol generated by the residue remains in the product, etc., and industrially, a method generally obtained by 2) dehydration ring closure imidization reaction of maleamic acid is performed.

On the other hand, maleic anhydride is generally added at a molar ratio of 1 or more to aniline to improve the yield of the maleimide and suppress the by-products. In the pre-distillation step, which is a purification step after completion of the reaction, isomers of maleic acid (MAH) and maleic acid (maleic acid, MA) which are hydrates of maleic anhydride (MAH) or maleic anhydride added in excess for ease of distillation conditions and ease of operation. It involves the process of washing the reaction mixture with water (water washing process) for the removal of fumaric acid (FA). However, in the washing process using water, a large amount of wastewater containing impurities is generated, which results in additional wastewater treatment facilities and high costs for maintaining them.

Accordingly, the present invention proposes a recycling method of wastewater containing maleic anhydride or maleic acid to solve the above problems.

KR 0045955 B1 (1991.11.12)

The problem to be solved of the present invention is to provide a method of recycling maleic anhydride or wastewater containing maleic acid.

The present invention is to solve the above problems,

1) preparing maleic anhydride and a primary amine by introducing maleic anhydride and primary amine in the presence of an organic solvent and a catalyst; And

2) washing the N-substituted maleimide producing solution with washing water to extract maleic anhydride or maleic acid;

3) isomerizing maleic anhydride or maleic acid to fumaric acid by adding a maleic acid isomerization catalyst to the maleic anhydride or maleic acid washed wastewater; And

4) provides an N-substituted maleimide wash water recycling method comprising the step of regenerating the wash water by filtering the fumaric acid in the wash waste water.

The present invention also provides a method for producing N-substituted maleimide, including the N-substituted maleimide wash water recycling method.

The present invention can recycle the wastewater generated in the N-substituted maleimide washing process, unlike the prior art has the effect of reducing the additional wastewater treatment facilities and costs for maintaining it.

In addition, it is possible to prevent the problem of N-substituted maleimide recontamination by regenerating and recycling the washing waste water.

Hereinafter, the present invention will be described in more detail to aid in understanding the present invention. At this time, the terms or words used in the present specification and claims should not be construed as being limited to the ordinary or dictionary meanings, and the inventors appropriately define the concept of terms in order to explain their invention in the best way. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that it can.

The present invention provides a method for preparing N-substituted maleimide solution by introducing maleic anhydride and primary amine in the presence of an organic solvent and a catalyst; And

2) washing the N-substituted maleimide producing solution with washing water to extract maleic anhydride or maleic acid;

3) isomerizing maleic anhydride or maleic acid to fumaric acid by adding a maleic acid isomerization catalyst to the maleic anhydride or maleic acid washed wastewater; And

4) provides an N-substituted maleimide wash water recycling method comprising the step of regenerating the wash water by filtering the fumaric acid in the wash waste water.

Hereinafter, the N-substituted maleimide wash water recycling method of the present invention and the N-substituted maleimide production method including the same will be described in detail.

Step 1)

Step 1) according to an embodiment of the present invention is a step for synthesizing N-substituted maleimide, by adding maleic anhydride and primary amine in the presence of an organic solvent and a catalyst to form an N-substituted maleimide solution It is characterized by manufacturing.

About the manufacturing method of a maleimide compound, 1) The method obtained by dehydrating maleic anhydride and a primary amine in one step, 2) The maleamic acid is produced | generated from maleic anhydride and a primary amine, and this malea The method obtained by the dehydration ring closure imidation reaction of a hydrochloric acid, 3) The method obtained by ring closure imidation reaction of the corresponding maleic acid monoester, etc. are mentioned.

However, in the 1) method of obtaining from a maleic anhydride and a primary amine by one step, there is still a problem that productivity is low because a yield is still low, and 3) by the ring-ring imidation reaction in the method obtained from a maleamic acid monoester. Since there is a problem that the generated alcohol remains in the product, the present invention is characterized in that N-substituted maleimide is synthesized by the dehydration ring closure imidization reaction of maleic acid.

The N-substituted maleimide of the present invention is acylated by heating maleic anhydride and primary amine in one step to obtain an intermediate N-substituted maleamic acid, and in two steps, the N-substituted horses on the surface of the catalyst. N-substituted maleimide can be synthesize | combined by the method of the dehydration ring closure imidation reaction of reamic acid.

In addition, in the process of obtaining N-substituted maleamic acid from the maleic anhydride and the primary amine, maleic anhydride or primary amine may be used as it is, but in the form of a solution dissolved in an organic solvent. It is desirable to. On the other hand, when using maleic anhydride or primary amine in the form of the solution which melt | dissolved in the organic solvent, the next dehydration ring closure imidation reaction of N-substituted maleamic acid can be performed in a solution (organic solvent) as it is.

The organic solvent is insoluble or immiscible in water, inert to the reaction and should not participate in the reaction so that water produced by the dehydration ring closure reaction of the N-substituted maleamic acid can be released out of the system via azeotropic distillation.

 In addition, it is suitable that the boiling point is at least 50 ° C. or higher for the smooth progress of the reaction, and the boiling point is lower than 250 ° C. for the stability of the resulting N-substituted maleimide. Examples of suitable organic solvents include benzene, toluene, xylene, o-xylene, ethylbenzene, isopropylbenzene, cumene, mesitylene, tert-butylbenzene, pseudocumene, trimethylhexane, octane, tetrachloroethane, Nonane, chlorobenzene, ethylcyclohexane, m-dichlorobenzene, sec-butylbenzene, p-dichlorobenzene, decane, p-cymene, o-dichlorobenzene, butylbenzene, decahydronaphthalene, tetrahydronaphthalene, dodecane, naphthalene , And cyclohexylbenzene, and the like, and the organic solvent may be used alone or in the form of a mixture of two or more thereof.

The amount of the organic solvent to be used is not particularly limited. However, the amount of the organic solvent is about 1 to 20 times (by weight), more preferably about 1% of the amount of the primary amine to be used as a raw material, in order to satisfy the economic conditions while smoothly carrying out the reaction. The range of 2 to 10 times (by weight) is appropriate. If the amount of the organic solvent is less than 2 times, there is a problem in that the yield is not easy to effectively remove the water produced through the dehydration ring-closure reaction of the N-substituted maleamic acid from the reaction system, if the amount exceeds 10 times synthesized In the process of separating the organic solvent from the N-substituted maleimide solution, excessive energy is consumed, which is not preferable from an economic point of view.

In addition, the organic solvent should be determined in consideration of environmental factors and solubility, price and ease of handling of N-substituted maleimide, and moreover, a solvent suitable for easy removal and reuse after completion of the reaction should be selected. Here, maleic anhydride and primary amine may be dissolved in the same organic solvent or in another organic solvent, but are preferably dissolved in the same organic solvent.

In addition, the concentration of maleic anhydride or primary amine in the case of using maleic anhydride or primary amine in the form of a solution dissolved in an organic solvent is not particularly limited as long as it can dissolve maleic anhydride or primary amine. Do not. Specifically, it is preferable to add and dissolve 0-500 g of organic solvents, More preferably, 10-200 g with respect to 100 g of maleic anhydride. Furthermore, it is preferable that 0-500 g of organic solvents, More preferably, 5-200 g are added and melt | dissolved with respect to 100 g of primary amines.

In one embodiment of the present invention, the primary amine is a saturated or unsaturated alkylamine having 1 to 20 carbon atoms, cycloalkylamine having 5 to 20 carbon atoms, cycloalkylamine having 6 to 20 carbon atoms or 6 to 20 carbon atoms One kind of primary amine selected from among aromatic alkylamines may be used, specifically, methyl amine, ethyl amine, n-propyl amine, isopropyl amine, n-butyl amine, sec-butyl amine, iso-butyl amine at least one selected from the group consisting of tert-butylamine, n-hexyl amine, n-octyl amine, n-decyl amine, n-dodecyl amine, cyclohexyl amine, and aniline, and N-phenyl maleimide In order to synthesize the aniline can be used as the primary amine.

In the present invention, the amount of maleic anhydride to be used is preferably in an amount of 1.0 to 1.1 molar ratio relative to the primary amine used in the synthesis of N-substituted maleimide. This is to improve the yield of the N-substituted maleimide synthesized and to suppress the by-products.

When maleic anhydride is used at less than 1.0 molar ratio, problems of yield reduction and by-products increase, and when it is used at more than 1.1 molar ratio, excess unreacted maleic anhydride remains after N-substituted maleimide synthesis. It is not preferable in terms of phosphorus.

On the other hand, the catalyst used in the synthesis of N-substituted maleimide may be directly used a solid or liquid catalyst of a homogeneous system or a solid acid catalyst of zeolite series or metal phosphate series.

On the other hand, the catalyst of the present invention should be added in an appropriate amount in terms of process operation and cost, specifically 2 to 15% by weight in the case of a homogeneous system, 5 to 30% by weight in the case of a heterogeneous system to the input reaction solvent It is preferable.

When the input amount is less than the above range, the ratio of N-substituted maleamic acid to be converted per unit time is low, so that the total reaction time is increased. When the input amount exceeds the above range, the reaction time according to the production of N-substituted maleamic acid as an intermediate product is exceeded. Agitation due to increased solids may not be smooth.

In some cases, the metal-containing compound and the stabilizer may be coexisted in the reaction system and reacted. The metal-containing compound used at this time is not particularly limited, but at least one metal oxide, acetate, maleate, succinate salt selected from the group consisting of zinc, chromium, palladium, cobalt, nickel, iron and aluminum. of succinic acid, nitrates, phosphates, chlorides and sulfates. Of these, zinc acetate is particularly effective. The amount of these used is 0.005 to 0.5 mol%, preferably 0.01 to 0.1 mol%, as a metal, based on maleic anhydride and / or primary amine as a raw material.

In addition, as a stabilizer, methoxybenzoquinone, p-methoxyphenol, phenothiazine, hydroquinone, alkylated diphenyl amines, methylene blue, tert-butyl catechol, tert-butylhydroquinone, dimethyldithiocarba Mate zinc, dimethyldithiocarbamate, copper dibutyldithiocarbamic acid, copper salicylate, thiodipropionic acid esters, mercaptobenzimidazole, triphenyl phosphite, alkyl phenols, alkyl bisphenols, and the like are used. The effect of these stabilizers plays a role of making the N-substituted maleimide produced by the dehydration ring closure imidization reaction stably exist without deterioration even at a high temperature of the imidization reaction. Although the addition amount is not specifically limited, 0.001 to 0.5 mol% can be used with respect to maleic anhydride and / or primary amine which are raw materials. Here, if it is such an addition amount, the said stabilizing effect can fully be exhibited and the problem mixed in a product can also be avoided.

The reaction temperature of the synthesis reaction of the N-substituted maleimide of step 1) of the present invention is generally 50 to 200 ° C, more preferably 100 to 160 ° C. If the synthesis reaction temperature is less than 50 ℃, a problem that the yield is lowered, if it exceeds 200 ℃ polymerization of the N-substituted maleimide proceeds as a side reaction to reduce the purity and yield of the synthesized N- substituted maleimide Problems may arise.

There is no particular limitation on the reaction pressure in the present invention, and it can be selected in a wide range from reduced pressure, atmospheric pressure and pressure. The reaction may vary depending on conditions such as the type of solvent, the amount of raw materials, the amount of catalyst and the reaction temperature, but is generally about 1 to 16 hours, more preferably within 1 to 10 hours.

Under such reaction conditions, the dehydration ring closure imidation reaction of the N-substituted maleamic acid proceeds efficiently, and the N-substituted maleimide can be efficiently obtained.

In addition, the N-substituted maleimide of the present invention may be selected from the group consisting of N-alkyl maleimides such as N-methyl maleimide, N-ethyl maleimide, N-hexyl maleimide, N-octyl maleimide and N-dodecyl maleimide; N-benzylmaleimide; N-cycloalkyl maleimides such as N-cyclohexyl maleimide; N-phenyl maleimide; And N-nitrophenyl maleimide, N-methoxyphenyl maleimide, N-methylphenyl maleimide, N-carboxyphenyl maleimide, N-hydroxyphenyl maleimide, N-chlorophenyl maleimide, N-dimethylphenyl maleimide Nitro groups such as N-dichlorophenyl maleimide, N-bromophenyl maleimide, N-dibromophenyl maleimide, N-trichlorophenyl maleimide, N-tribromophenyl maleimide, alkoxy groups, alkyl groups It may be at least one selected from the group consisting of N-substituted phenyl maleimide substituted with a carboxyl group, a hydroxyl group, a halogen atom and a phenyl group.

Step 2)

Step 2) according to an embodiment of the present invention is a water washing process step, wherein the N-substituted maleimide solution generated in step 1) is washed with washing water to extract maleic anhydride or maleic acid. It is done.

Meanwhile, the N-substituted maleimide production solution refers to a liquid component excluding the catalyst and solid components for preparing N-substituted maleimide after step 1).

The water washing process refers to a process of extracting a component having a higher solubility in water than an organic solvent into an aqueous layer by mixing with water and stirring the organic solvent to be separated from the water layer.

In step 1), a step of synthesizing N-substituted maleimide, maleic anhydride is added in a molar ratio of 1 or more with respect to the primary amine in order to improve the yield of N-substituted maleimide and suppress by-products.

In the pre-distillation step, the purification step after the completion of the synthesis reaction, the maleic anhydride (maleic acid, MA), which is a hydrate of the excess maleic anhydride or maleic anhydride, should be removed for ease of distillation conditions and ease of operation of the distillation column. The maleic anhydride or maleic acid is an impurity having a low boiling point, which is not easy to separate in the distillation process, so that the maleic anhydride or maleic acid is more reliably removed in the pre-distillation step.

Accordingly, the present invention is characterized in that the maleic anhydride or maleic acid having higher solubility in water than the organic solvent is washed with washing water and extracted from the N-substituted maleimide producing solution.

In addition, the washing water is preferably added 40 to 120% by weight, preferably 50 to 100% by weight relative to the weight of the N- substituted maleimide production solution. When added in the above range, it is possible to reduce the amount of washing waste water generated while the impurities removal efficiency is good.

In addition, the washing process is preferably carried out at 30 to 80 ℃, preferably 50 to 70 ℃. It is because it is excellent in the maleic anhydride or maleic acid extraction effect, while being able to prevent the loss of N-substituted maleimide by precipitation of N-substituted maleimide in the said range.

Step 3)

Step 3) according to an embodiment of the present invention, isomerization of maleic anhydride or maleic acid to fumaric acid by adding a maleic acid isomerization reaction catalyst to the washing wastewater from which maleic anhydride or maleic acid was extracted in step 2). It is characterized by reacting.

Fumaric acid (FA), an isomer of maleic acid, has a very low solubility in water, and is intended to remove maleic anhydride or maleic acid having high solubility in water and convert it to fumaric acid. For example, at 20 ° C., the solubility of maleic acid in 100 g of water is 70 g and fumaric acid is 0.5 g.

The maleic acid isomerization catalyst is characterized in that at least one selected from the group consisting of potassium thiocyanate (KSCN), sodium thiocyanate (NaSCN) and ammonium thiocyanate (NH ₄ SCN), the catalyst is maleic anhydride or maleic acid 3 to 15% by weight, preferably 5 to 10% by weight based on the weight of the washing waste water, characterized in that the addition.

When added in a smaller amount than the above range, there is a problem that the isomerization reaction rate is slow, and the addition in excess of the above range is preferably added in the above range from the economical point or the reaction rate does not have a large difference.

The isomerization reaction may be performed at 60 to 110 ° C., preferably at 90 to 100 ° C. for 1 to 5 hours. It is more preferable that the isomerization reaction efficiency is high in the above temperature and time range.

Step 4)

Step 4) according to an embodiment of the present invention is a step of completing the regeneration of the washing wastewater, characterized in that the washing water by filtering the fumaric acid in the washing wastewater.

The fumaric acid has a very low solubility in water, and the lower the solubility, the lower the temperature. In order to precipitate fumaric acid dissolved in the washing wastewater, the washing wastewater is cooled to room temperature (25 ° C.) at an isomerization reaction temperature. Do. Fumaric acid precipitated as a solid can be removed from the washing waste water through simple filtration.

The regenerated wash water can be reused in the next batch. On the other hand, the regenerated wash water includes a maleic acid isomerization catalyst. The maleic acid isomerization catalyst has a very high solubility in water (about 217 g / 100 ml water at 20 ° C.) and the catalyst may remain in the wash water even after filtration of fumaric acid. Therefore, it is not necessary to add a maleic acid isomerization catalyst when reusing the regenerated washing water, thereby simplifying the process and reducing the purchase cost of the maleic acid isomerization catalyst.

Since the washing wastewater generated after the conventional washing process contains maleic anhydride or maleic acid as an impurity, the N-substituted maleimide-producing solution is recontaminated when it is repeatedly used in a water washing process, but the present invention is water-soluble maleic acid isomerization. By using a reaction catalyst, maleic anhydride or maleic acid is converted into fumaric acid and removed from the washing waste water, thereby allowing the washing water to be recycled, and recycling of N-substituted maleimide can be prevented even by recycling.

Therefore, according to the present invention can be recycled repeatedly without the external discharge of waste water is environmentally friendly, it is possible to reduce additional facilities and maintenance costs for waste water treatment.

N-substitution Maleimide  Manufacturing method

N-substituted maleimide production method of the present invention may include the N-substituted maleimide wash water recycling method of the present invention, specific N-substituted maleimide production conditions are as salping in step 1).

The N-substituted maleimide production method of the present invention uses the N-substituted maleimide wash water recycling method, and can be recycled by recycling the N-substituted maleimide wash waste water, thereby reducing additional wastewater treatment facilities and costs for maintaining the same. In terms of the economy and productivity are excellent.

Example  One

In a 100 mL reactor with a stirrer, a thermometer, a water separator and a cooler, 53 g of o-xylene, 50.0 g of aniline and 55.3 g of maleic anhydride and 5.3 g of zirconium hydrogen phosphate were melted at 80 ° C. After the addition, the temperature of the reaction system was raised to 140 ° C to synthesize N-phenyl maleimide. Water generated by the dehydration ring closure reaction was removed out of the reaction system with o-xylene through azeotropic distillation. The o-xylene removed from the reaction system was subjected to the synthesis reaction for 4 hours while being re-administered into the reaction system.

After the synthesis reaction, 100% by weight of washing water was added to the weight of the N-phenyl maleimide production solution obtained by decantation of the liquid component except the catalyst, followed by washing with water at 70 ° C. for 1 hour to extract maleic anhydride and maleic acid. Was performed.

After the extraction process was carried out to measure the amount of maleic anhydride and maleic acid contained in the wash water of the separated water layer to obtain a value of 10% by weight. Potassium thiocyanate (KSCN) catalyst required for isomerization of maleic anhydride and maleic acid was added by 10 wt% based on the weight of the wash water, and heated at 100 ° C. for 2 hours to complete the isomerization reaction and then cooled to room temperature.

After the precipitated fumaric acid was filtered to complete the regeneration of the wash water.

Example  2

In the same manner as in Example 1, N-phenyl maleimide production solution was prepared, and the wash water (filtrate filtered through fumaric acid), regenerated in Example 1, was added as much as 100% by weight based on the weight of the solution. A water washing process was performed to extract maleic anhydride and maleic acid for a time. Thereafter, the aqueous layer was separated and heated at 100 ° C. for 2 hours to complete the isomerization reaction, and then cooled to room temperature.

After the precipitated fumaric acid was filtered to complete the regeneration of the wash water.

Example  3

Regeneration of the wash water was completed in the same manner as in Example 1 except that 15 wt% of the potassium thiocyanate (KSCN) catalyst was added based on the weight of the wash water.

Example  4

In Example 2, the regeneration of the washing water was completed in the same manner as in Example 2 except that the washing water regenerated in Example 3 was added instead of the washing water regenerated in Example 1.

Comparative example  One

Except for the addition of potassium thiocyanate (KSCN) catalyst 2 wt% based on the weight of the wash water in Example 1 to complete the regeneration of the wash water in the same manner as in Example 1.

Comparative example  2

Regeneration of the washing water was completed in the same manner as in Example 2 except that the washing water regenerated in Comparative Example 1 was added instead of the washing water regenerated in Example 1 in Example 2.

Experimental Example

In the Examples and Comparative Examples, the following physical properties were measured and the results are shown in Table 1 below.

1) Measurement of yield of fumaric acid

The yields of fumaric acid produced and filtered during the regeneration of the Examples and Comparative Examples are shown in Table 1 below, calculated by the following formula.

% Yield of fumaric acid = [(weight of filtered fumaric acid) / (maleic anhydride and maleic acid contained in the wash water)] × 100%)

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Yield of fumaric acid (%) 74 67 72 69 36 44

As shown in Examples 1 and 3 of Table 1, the present invention can be removed by isomerization of maleic anhydride or maleic acid contained in the washing waste water with high yield of fumaric acid, as shown in Examples 2 and 4 Likewise, it was confirmed that the maleic anhydride or the maleic acid removal effect was excellent even when the washed water regenerated in Examples 1 and 3 was reused.

However, in the case of Comparative Examples 1 and 2 it was found that the yield of fumaric acid is remarkably low, which is expected to be due to the addition of a small amount of maleic acid isomerization catalyst to complete regeneration.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims (9)

1) preparing maleic anhydride and a primary amine by introducing maleic anhydride and primary amine in the presence of an organic solvent and a catalyst; And
2) washing the N-substituted maleimide producing solution with washing water to extract maleic anhydride or maleic acid;
3) isomerizing maleic anhydride or maleic acid to fumaric acid by adding a maleic acid isomerization catalyst to the maleic anhydride or maleic acid washed wastewater; And
4) N-substituted maleimide washing water recycling method comprising the step of regenerating the washing water by filtering the fumaric acid in the washing waste water.
The method of claim 1,
The washing water is N-substituted maleimide wash water recycling method, characterized in that 40 to 120% by weight relative to the weight of the N- substituted maleimide production solution.
The method of claim 1,
N-substituted maleimide wash water recycling method, characterized in that the washing is carried out at 30 to 80 ℃.
The method of claim 1,
The maleic acid isomerization catalyst is potassium thiocyanate (KSCN), sodium thiocyanate (NaSCN) and ammonium thiocyanate (NH ₄ SCN) N-substituted maleimide wash water recycling method, characterized in that at least one selected from the group consisting of.
The method of claim 1,
The maleic acid isomerization catalyst is N-substituted maleimide wash water recycling method characterized in that the addition of 3 to 15% by weight relative to the weight of the washing waste water.
The method of claim 1,
The isomerization reaction is N-substituted maleimide wash water recycling method, characterized in that at 60 to 110 ℃.
The method of claim 1,
N-substituted maleimide wash water recycling method, characterized in that for reuse the wash water recycled by step 4).
The method of claim 1,
The N-substituted maleimide may be N-alkyl maleimide such as N-methyl maleimide, N-ethyl maleimide, N-hexyl maleimide, N-octyl maleimide, N-dodecyl maleimide; N-benzylmaleimide; N-cycloalkyl maleimides such as N-cyclohexyl maleimide; N-phenyl maleimide; And N-nitrophenyl maleimide, N-methoxyphenyl maleimide, N-methylphenyl maleimide, N-carboxyphenyl maleimide, N-hydroxyphenyl maleimide, N-chlorophenyl maleimide, N-dimethylphenyl maleimide Nitro groups such as N-dichlorophenyl maleimide, N-bromophenyl maleimide, N-dibromophenyl maleimide, N-trichlorophenyl maleimide, N-tribromophenyl maleimide, alkoxy groups, alkyl groups N-substituted maleimide wash water recycling method, characterized in that at least one selected from the group consisting of a carboxyl group, a hydroxyl group, a halogen group substituted with a phenyl group N-substituted phenyl maleimide.
N-substituted maleimide production method comprising the N-substituted maleimide wash water recycling method of any one of claims 1 to 8.