KR100923536B1 - Method for preparation of the N-substitution maleimide - Google Patents

Abstract

The present invention relates to a method for producing N-substituted maleimide, and more particularly, unlike the method for preparing N-substituted maleimide after preparing existing N-substituted maleamic acid, N-substituted maleamide The present invention relates to a method for producing N-substituted maleimides of high purity and high yield by effectively inhibiting maleimide polymer formation using tertiary amines as cocatalysts without preparing an acid separately.

In particular, the present invention has the advantage that the process is simplified and the yield is high, while eliminating expensive raw material input and difficult reaction liquid treatment while minimizing side reactions, significantly reducing the input time of the raw material and maleic anhydride.

Manufacturing method of N-substituted maleimide, tertiary amine

Description

Method for preparation of the N-substitution maleimide

The present invention relates to a method for producing N-substituted maleimide.

N-substituted maleimides are useful as starting materials or intermediates for medicines, pesticides, dyes, polymer compounds, etc., and in particular, they are recently used in large amounts to improve the heat resistance of styrene-based resins. It is widely used as a copolymer for polymer blending.

Several methods are known as a manufacturing method of conventional N-substituted maleimide. A general production method is a reaction in which maleic anhydride and amines are reacted to obtain N-substituted maleic amic acid, which is dehydrated and closed to imidize. As an example of a known method, there is a method of dehydrating and closing N-substituted maleic amic acid obtained by heating maleic anhydride and amines at 180 ° C. [L.E. Coleman et al., J. Org, Chem., 24, 135-136 (1959). However, according to this method, the yield of the desired N-substituted maleimide can be obtained only about 15 to 50%, which is economically invaluable.

As a method for producing N-substituted maleimide having a relatively high yield, there are a method of using a dehydrating agent and a dehydration catalyst in the method of dehydrating ring closure of N-substituted maleamic acid.

One example of a method of using a dehydrating agent is well known a method for dehydrating N-substituted maleic amic acid using a dehydrating agent such as acetic anhydride in the presence of a sodium acetate catalyst as known from US Pat. No. 2,444,536. This method provides a relatively high reaction yield, but it is difficult to be an economical mass production method due to the disadvantage that the production cost is high because a large amount of dehydrating agent is used and complicated product separation treatment is required after the reaction.

One method that is considered to be industrially advantageous is the dehydration cyclization of the N-substituted maleamic acid under mild conditions using an effective dehydration catalyst in place of the dehydrating agent. This method can be an economically advantageous method because it does not use expensive subsidiary materials. U.S. Patent No. 3,431,276 discloses water produced by heating and dehydrating N-substituted maleic amic acid using an acid catalyst such as sulfur trioxide, sulfuric acid, orthophosphoric acid in a solvent having a moderate boiling point without using a chemical dehydrating agent. A method of producing N-substituted maleimides by introducing azeotropic distillation together with removal from the system has been introduced. This method does not use a large amount of expensive dehydrating agent and has the advantage of easily separating the generated N-substituted maleimide, but the reaction yield is not high, there is a problem that easy to accompany side reactions. Japanese Patent Laid-Open Publication Nos. 53-68,770 and 57-42,043 disclose an aprotic polarity such as dimethylformamide or dimethyl sulfoxide after the production of N-substituted maleamic acid. The method of obtaining N-substituted maleimide by using a solvent to increase the solubility of N-substituted maleic amic acid and then dehydrating and closing the ring in the presence of an acid catalyst was used. Yield is greatly improved by the influence of aprotic polar solvents, but the production cost is increased by using a large amount of expensive, highly toxic aprotic polar solvents, and the aprotic polar solvents can be altered by an acid catalyst during the reaction. Since it is wasted and mostly has a high boiling point, there is a problem that a lot of energy is required to separate from the N-substituted maleimide.

U.S. Patent Nos. 4,623,734, 4,780,546, and 4,786,738 disclose N-substituted maleamic acid by reacting maleic anhydride with amines in a nonpolar organic solvent, followed by azeotropic distillation in the presence of an acid catalyst, a metal stabilizer, and other stabilizers to dehydrate the ring. It was presented how to. However, such a method cannot produce highly purified N-substituted maleimide compounds and the separation of the reaction solution and the catalyst performed after completion of the reaction is very difficult due to the by-products generated during the reaction. Even though the separation proceeds, there is a problem that the activity of the catalyst is sharply lowered and cannot be effectively reused, which is why it is not an advantageous method from an economic point of view.

In the case of U.S. Patent No. 4,851,547, a content of supporting the catalyst by using a solid support was proposed to facilitate the separation of the catalyst. This method seems to be suitable for economical view by providing a considerable degree of yield and purity, however, maleic anhydride and amines are first reacted to prepare N-substituted maleamic acid, and then separately prepared in the prepared N-substituted maleamic acid. By applying an amine salt treated with an acid as a catalyst, it is inconvenient to operate the reactor separately, and there is a problem in that N-substituted maleic amide acid or amine salt in a slurry state is transferred. In addition, there is a problem that a large amount of 2-amino-N-substituted succinimide is generated as a by-product due to the application of excess amines during the reaction. Since the amines that should act as catalysts actually participate in the reaction, they are not suitable for the production of high purity N-substituted maleimides.

U.S. Patent No. 4,980,483 uses the phenomenon that 2-amino-N-substituted succinimide, a major by-product, reacts with maleic anhydride and is selectively converted to N-substituted maleimides. N-substituted maleimide of high yield and purity by reacting the excess of maleic anhydride in the second reaction after proceeding the reaction under the condition of excess amine, which is a condition that 2-amino-N-substituted succinimide can be produced. Claimed to be obtained. However, large amounts of 2-amino-N-substituted succinimides are converted to N-substituted maleimides only in excess maleic anhydride conditions, and unconverted 2-amino-N-substituted succinimides are impurity to the final state of the product. It is not suitable for fields that require highly purification. In addition, 2-amino-N-substituted succinimide included in the polymer compound may result in unsuitable products such as carbonizing the surface of the polymer compound or irregularizing the surface of the final product, so removal is essential.

US Pat. No. 5,973,166 proposes a method in which a large amount of amine salt is applied in place of the aprotic polar solvent used for the purpose of increasing the solubility of reactants, intermediates and products in the conventional maleimide manufacturing method. However, as with other preparation methods, the problems caused by preparing N-substituted maleic amic acid first and the overall low yield, and the disadvantages of the complicated purification process using recrystallization. In addition, by applying a large amount of expensive amine salt is not an advantageous method from the economic point of view.

Accordingly, the present inventors have studied the preparation method for minimizing side reactions in the production of N-substituted maleimide reaction is simpler than the existing methods, provide a high yield, and as a result, N-substituted maleimide Without preparing amic acid first, an acid catalyst was added to an organic solvent, and then an amine salt was formed with a tertiary amine not related to the product to act as a cocatalyst. Amine salt is formed under the catalyst, and then metal-containing compounds such as zinc acetate and stabilizer are added, followed by maleic anhydride and dehydration ring-closure reaction to add expensive raw materials and difficult reaction solution treatment. Excludes and does not use high boiling point aprotic polar solvent, simple purification process, easy catalyst separation and reuse This invention was completed by developing the manufacturing method of substituted maleimide.

In the present invention, an organic solvent, an acid catalyst, a dehydration promoter and a stabilizer are added to a reactor, and then tertiary amine and primary amine are added to amine chloride, and maleic anhydride is added to dehydration ring-closure reaction. A method of producing N-substituted maleimide having high purity and high yield by azeotropic distillation with an organic solvent is characterized by the above-mentioned method.

The production of N-substituted maleimide using the amine salt according to the present invention as a reactant and catalyst can give a higher yield and purity than the method of preparing N-substituted maleimide after preparing the existing N-substituted maleamic acid. It was confirmed that there is. In addition, it can be seen that moderate amounts of tertiary amines result in higher yields and purity, providing higher yields with the appropriate addition of maleic anhydride.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method for producing N-substituted maleimide, and more particularly, unlike the method for preparing N-substituted maleimide after preparing existing N-substituted maleamic acid, N-substituted maleamide The present invention relates to a method for producing N-substituted maleimide having high purity and high yield by effectively inhibiting maleimide polymer formation by using tertiary amine as a cocatalyst without separately preparing an acid.

First, the composition components used to prepare the N-substituted maleimide according to the present invention will be described.

Examples of primary amines particularly useful as raw materials for maleimide used in the present invention include methylamine, ethylamine, n-propylamine, i-propylamine, s-propylamine, n-butylamine, s-butylamine, i Butylamine, t-butylamine, n-hexylamine, n-dodecylamine, allylamine, benzylamine, cyclohexylamine, aniline, ethylaniline, toluidine, hydroxyaniline, nitroaniline or ethylenediamine can be used. Do.

The organic solvent used in the present invention is insoluble or immiscible in water, inert to the reaction so that water produced by the dehydration ring closure reaction of N-substituted maleamic acid can be released out of the system through azeotropic distillation. Do not participate in 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 170 ° C. for the stability of the resulting N-substituted maleimide. Examples of suitable organic solvents for this reaction include benzene, toluene, xylene, ethylbenzene, cumene, chlorobenzene, isopropylbenzene, mesitylene, t-butylbenzene, trimethyl hexane, octane, and the like. In addition, the amount of the organic solvent used in the reaction suitable for economical viewpoint is about 1 to 20 times (by weight), and more preferably about 2 to 10 times (by weight) of the amount of primary amine used as a raw material. It is suitable.

In addition, the organic solvent should be determined in consideration of environmental factors, solubility, cost and ease of handling of raw materials and products, and a solvent suitable for easy removal and reuse after the reaction should be selected. In addition, the above-described organic solvents may be applied alone or in combination, and the mixing ratio may be determined to suit the above purpose.

Materials that can be used as acid catalysts suitable for the present invention are inorganic or organic monohydrochloric acids and polybasic acids such as sulfuric anhydride, p-toluenesulfonic acid, orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, benzenesulfonic acid and trichloracetic acid. The amount of such catalyst used is preferably in the range of about 10 to 200 moles, more preferably 20 to 100 moles, relative to 100 moles of primary amine applied to the reaction. If the catalyst is used in less than 10 mole parts, there is a problem that the reaction does not proceed smoothly, when more than 200 mole parts there is a problem of yield reduction and side reaction formation.

On the other hand, the catalyst can be used alone or supported on a carrier. At this time, examples of the support that can support the catalyst, synthetic minerals such as activated carbon, silica, silica-alumina, titanium dioxide and zirconium oxide, natural minerals such as clay, talc, diatomaceous earth, bentonite, montmorillonite, etc. There is this. Such inorganic carriers are used in the form of powders, in the form of granules obtained by granulation and classification with related substances, and the like. Preferred carriers for catalysis are particularly advantageous when catalyzed by a porous material such as diatomaceous earth, silica gel or activated carbon, and the amount of the carrier described above is 0.2 to 4 times the weight of the catalyst (by weight), preferably 0.5 ~ 2 times (by weight) is appropriate.

It may be better to proceed with the reaction in the presence of stabilizers for the stabilization of the metal-containing compound and the resulting product as a dehydration promoter during the production of maleimides. At this time, the metal-containing compound that can be used is at least selected from the group consisting of zinc (Zn), chromium (Cr), palladium (Pd), cobalt (Co), nickel (Ni), iron (Fe) and aluminum (Al). It may be selected from oxides, acetates, maleates, succinates and chlorides of one metal. In particular, zinc acetate is most effective, and the amount of the metal-containing compound is in the range of 0.005 to 0.5 mole parts, preferably 0.01 to 0.2 mole parts relative to 100 moles of primary amine. If the dehydration promoter is used in less than 0.005 mole parts, there is a problem that the reaction time is delayed, and when the dehydration promoter is more than 0.5 mole parts, the side reaction proceeds and there is a problem of lowering the catalytic activity.

Stabilizers effective for the present invention include methoxybenzoquinone, p-methoxyphenol, phenothiazine, hydroquinone, alkylated diphenylamine, methyleneblue, t-butylcatechol, t-butyl hydroquinone, zinc dimethyldithio carbamate, At least one selected from copper dimethyldithio carbamate, alkylphenols and alkylbisphenols is suitable. The addition amount of the stabilizer is not sufficient to stabilize the effect when added in a small amount, excessive care should be taken because it affects the production of the final product, especially high molecular compound. The preferred dosage is in the range of 0.005 to 0.5 mole parts, more preferably 0.05 to 0.3 mole parts relative to 100 moles of primary amine. If the stabilizer is used at less than 0.005 mole parts, there is a problem in that the maleimide polymer is formed, and if it is more than 0.5 mole parts, there is a problem in that it may act as a catalyst poison of the polymer polymerization when acting as a monomer under the influence of excessive stabilizer on the final product.

Tertiary amines can be used as promoters for the dehydration ring closure reaction, and suitable tertiary amines can control acidity in the system to control excessive reactions and can effectively inhibit polymer production of the N-substituted maleimide produced. Examples of tertiary amines that can be used in the present invention include trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trioctylamine, tribenzylamine, and the like. It is 0.05-50 mol parts with respect to 100 mol parts of primary amines, Preferably it is in the range of 0.01-20 mol parts. If the tertiary amine is used less than 0.05 mole parts, there is a problem that can not effectively suppress the side reactions, if more than 50 mole parts there is a problem that the yield reduction and washing process is not smooth.

In the present invention, maleic anhydride is added after the formation of the amine salt, it is preferable to use 100 to 150 mol parts with respect to 100 mol parts of the primary amine. In addition, in addition to the addition after the amine salt formation as described above, maleic anhydride may be added to obtain higher purity and yield after the reaction. An additional amount of 0.1-30 mol% of the total amount of maleic anhydride used is suitable.

In the manufacturing method of this invention, reaction temperature is generally 50-200 degreeC, More preferably, it is 70-160 degreeC. There is no particular limitation on the pressure in the present invention, but may be selected from a wide range of pressure, atmospheric pressure and pressure. The reaction time varies depending on the conditions such as the type of solvent, the input amount of the raw material, the amount of catalyst and the reaction temperature, but is generally about 1 to 16 hours, more preferably within 1 to 10 hours.

In the present invention, the reaction is performed by adding an organic solvent to the reactor, an acid catalyst and a carrier as necessary, followed by a dehydration catalyst and a stabilizer, followed by tertiary amine and the desired N-substituted maleimide. After the primary amine to be produced is added to amine chloride part or the whole, maleic anhydride is temporarily or dividedly added to dehydration and ring-closing reaction. Yields of N-substituted maleimides can be prepared. The solvent and catalyst used in the reaction can be easily separated and used in the next reaction without modification.

The present invention eliminates the process of making N-substituted maleic amic acid separately from existing methods. Therefore, only one reactor can be used, and the process of transporting the slurry phase N-substituted maleamic acid can be omitted, which simplifies the process, eliminates the inconvenience of transferring the N-substituted maleamic acid slurry, and separate reactors. There is an advantage to complete the reaction in one reactor without the need to operate. In addition, when using the method according to the present invention it was confirmed that it can have a higher yield and purity than the preparation of N-substituted maleimide after the production of N-substituted maleamic acid. More details will be revealed through experimental examples.

In addition, unlike the existing methods of forming the same kind of amine salt and using it as a catalyst separately from the amines participating in the reaction, the present reaction is carried out by forming an amine directly participating in the reaction with an amine salt and reacting with an excess amount in the system. Prevent the use of amines. Through this, it does not form 2-amino-N-substituted succinimide, which is a major by-product, and is superior in economical efficiency by using only an equivalent amount. In addition, in the case of adding amines, the conventional method requires an input time of at least 30 minutes to 1 hour or more to avoid side reactions in forming N-substituted maleimide. This has the advantage of shortening the time.

In the case of the addition of maleic anhydride, the conventional method is to introduce maleic anhydride into the organic solvent first, so that the maleic anhydride is added within a short period of time to prepare the reaction. There is an advantage to prevent deterioration. This result can be suppressed the production of maleic anhydride of maleic anhydride or fumaric acid produced by the rearrangement reaction to give a higher yield and purity than conventional results.

Hereinafter, the present invention will be described in more detail with reference to the following Examples, but the present invention is not limited thereto.

Example 1

40 kg of xylene was charged into a capacity 100 L reactor equipped with a thermometer, cooler with water separator and stirrer. Subsequently, 2 kg of silica gel was added to the support, followed by 2 kg (17.3 mol) of orthophosphoric acid.

Then 30 g (0.19 mol) of zinc acetate and 30 g (0.14 mol) of 2,4-dimethyl-6-t-butylphenol were added thereto. 100 g (0.98 mol) of triethylamine was added to form an amine salt through neutralization with acid, and 4 kg (43.0 mol) of aniline was added to the reactor for 5 minutes. The injected aniline was neutralized with the acid on the supported catalyst and converted into a white amine salt. Subsequently, 4.6 kg (47.3 mol) of maleic anhydride was added to the reactor for 5 minutes, and the reactor temperature was maintained at 140 ° C. under stirring, and the produced water was azeotropically distilled with xylene to be removed out of the system through a water separator. After the reaction was performed for 6 hours while maintaining the temperature, the mixture was allowed to stand and cooled to 30 ° C. to separate the catalyst layer through layer separation. The xylene solution layer was transferred to a separate neutralization tank, 500 g of 5% aqueous sodium carbonate solution was added thereto, and the mixture was left for 20 minutes after stirring. The solution was cleanly separated into an organic layer and an aqueous layer and the aqueous layer was separated off. Then, 500 g of water was added thereto, stirred for 20 minutes, and left standing for 20 minutes to wash. The aqueous layer was separated off. The separated organic layer was transferred to a concentration tank, and then distilled under reduced pressure to 20 to 130 mmHg at 50 ~ 100 ℃ to remove xylene. After removal of the solvent 7.2 kg of light yellow solid was obtained in a concentration bath. As a result of liquid chromatography, the purity of N-phenylmaleimide was 98%, and the yield of N-phenylmaleimide was calculated to be 97% based on aniline.

Example 2

40 kg of xylene was charged into a capacity 100 L reactor equipped with a thermometer, cooler with water separator and stirrer. Subsequently, 2 kg of silica gel was added to the support, followed by 2 kg (17.3 mol) of orthophosphoric acid. Then 30 g (0.19 mol) of zinc acetate and 30 g (0.14 mol) of 2,4-dimethyl-6-t-butylphenol were added thereto. 200 g (0.98 mol) of triethylamine was added thereto to form an amine salt through neutralization with acid, and 4 kg (43.0 mol) of aniline was added to the reactor for 5 minutes. The injected aniline was neutralized with the acid on the supported catalyst and converted into a white amine salt. Subsequently, 4.6 kg (47.3 mol) of maleic anhydride was added to the reactor for 5 minutes, and the reactor temperature was maintained at 140 ° C. under stirring, and the produced water was azeotropically distilled with xylene to be removed out of the system through a water separator. After the reaction was performed for 3 hours while maintaining the temperature, 200 g of maleic anhydride was further added, followed by further reaction for 3 hours. The reactor was left to stand and cooled to 30 ° C. to separate the catalyst bed through bed separation. The xylene solution layer was transferred to a separate neutralization tank, 500 g of 5% sodium carbonate aqueous solution was added thereto, and the mixture was left standing for 20 minutes after stirring. The solution was cleanly separated into an organic layer and an aqueous layer and the aqueous layer was separated off. Then, 500 g of water was added thereto, stirred for 20 minutes, and left standing for 20 minutes to wash. The aqueous layer was separated off. The separated organic layer was transferred to a concentration tank, and then distilled under reduced pressure to 20 to 130 mmHg at 50 ~ 100 ℃ to remove xylene. After removing the solvent 7.3 kg of a light yellow solid was obtained in a concentration bath. As a result of liquid chromatography, the purity of N-phenylmaleimide was 99%, and the yield of N-phenylmaleimide was calculated to be 97% based on aniline.

Example 3

Except for adding 300 g (2.94 mol) of triethylamine in Example 2 was carried out in the same manner (primary amine input time: 5 minutes, maleic anhydride time: 5 minutes). The result was 7.3 kg of a light yellow solid in a concentration bath. As a result of liquid chromatography, the purity of N-phenylmaleimide was 99%, and the yield of N-phenylmaleimide was calculated to be 98% based on aniline.

Example 4

Except that 3 kg (26.0 mol) of orthophosphoric acid as a catalyst was added in Example 1, the remainder was performed in the same manner (primary amine input time: 5 minutes, maleic anhydride time: 5 minutes). As a result, 7.1 kg of a tan solid was obtained in a concentration tank. As a result of liquid chromatography, the purity of N-phenylmaleimide was 97%, and the yield of N-phenylmaleimide was calculated to be 96% based on aniline.

Example 5

Except that 1 kg (8.7 mol) of orthophosphoric acid as a catalyst in Example 1 was carried out in the same manner was carried out (primary amine input time: 5 minutes, maleic anhydride time: 5 minutes). As a result, 7.1 kg of a tan solid was obtained in a concentration tank. As a result of liquid chromatography, the purity of N-phenylmaleimide was 97%, and the yield of N-phenylmaleimide was calculated to be 96% based on aniline.

Example 6

Except that 30 kg of xylene as a solvent was added in Example 1 was carried out in the same manner (primary amine input time: 5 minutes, maleic anhydride input time: 5 minutes). As a result, 7.1 kg of a tan solid was obtained in a concentration tank. As a result of liquid chromatography, the purity of N-phenylmaleimide was 97%, and the yield of N-phenylmaleimide was calculated to be 96% based on aniline.

Example 7

In Example 1, except that 20 g (0.12 mol) of t-butyl catechol was added instead of 2,4-dimethyl-6-t-butylphenol as a stabilizer (the primary amine input time: 5 minutes, maleic anhydride input time: 5 minutes). The result was 7.2 kg of a tan solid. As a result of the liquid chromatography analysis, the purity of N-phenylmaleimide was 97%, and the yield of N-phenylmaleimide was calculated to be 97% based on aniline.

Example 8

In Example 2, except that 400 g of maleic anhydride was additionally added after 3 hours of reaction time, the same procedure was performed (primary amine input time: 5 minutes, maleic anhydride time: 5 minutes, additional male anhydride). Acid input: 1 min). The result was 7.3 kg of a light yellow solid in a concentration bath. As a result of liquid chromatography, the purity of N-phenylmaleimide was 99%, and the yield of N-phenylmaleimide was calculated to be 98% based on aniline.

Example  9

In Example 2, the reaction was carried out in the same manner except adding 800 g of maleic anhydride after 3 hours of reaction time (primary amine input time: 5 minutes, maleic anhydride time: 5 minutes, additional male anhydride). Acid input: 1 min). The result was 7.2 kg of a tan solid. As a result of the liquid chromatography analysis, the purity of N-phenylmaleimide was 97%, and the yield of N-phenylmaleimide was calculated to be 97% based on aniline.

Example 10

40 kg of xylene was charged into a capacity 100 L reactor equipped with a thermometer, cooler with water separator and stirrer. Subsequently, 2 kg of silica gel was added to the support, followed by 2 kg (17.3 mol) of orthophosphoric acid. Then 30 g (0.19 mol) of zinc acetate and 30 g (0.14 mol) of 2,4-dimethyl-6-t-butylphenol were added thereto. 200 g (1.96 mol) of triethylamine was added to form an amine salt through neutralization with an acid, and 4 kg (40.3 mol) of cyclohexylamine was added to the reactor for 5 minutes. The cyclohexylamine added was neutralized with the acid on the supported catalyst and converted into a white amine salt. Subsequently, 4.4 kg of maleic anhydride was added to the reactor for 5 minutes, and the reactor temperature was maintained at 140 ° C., and the produced water was azeotropically distilled with xylene and removed out of the system through a water separator. After the reaction was performed for 3 hours while maintaining the temperature, 200 g of maleic anhydride was further added, followed by further reaction for 3 hours. The reactor was left to stand and cooled to 30 ° C. to separate the catalyst bed through bed separation. The xylene solution layer was transferred to a separate neutralization tank, 500 g of 5% aqueous sodium carbonate solution was added thereto, and the mixture was left for 20 minutes after stirring. The solution was cleanly separated into an organic layer and an aqueous layer and the aqueous layer was separated off. Then, 500 g of water was added thereto, stirred for 20 minutes, and left standing for 20 minutes to wash. The aqueous layer was separated off. The separated organic layer was transferred to a concentration tank, and then distilled under reduced pressure to 20 to 130 mmHg at 50 ~ 100 ℃ to remove xylene. After removal of the solvent 7.1 kg of a light white solid was obtained in a concentration bath. As a result of liquid chromatography, the purity of N-phenylmaleimide was 98%, and the yield of N-phenylmaleimide was calculated to be 97% based on aniline.

Examples 11-16

The experiment was conducted in the same manner as in Example 1 for each condition. The results of each example are shown in Table 1 below.

TABLE 1

Comparative Example 1

20 kg of xylene was charged into a capacity 100 L reactor equipped with a thermometer, cooler with water separator and stirrer. Subsequently, 2 kg of silica gel was added to the support, followed by 2 kg (17.3 mol) of orthophosphoric acid. Subsequently, 30 g (0.19 mol) of zinc acetate and 30 g (0.14 mol) of 2,4-dimethyl-6-t-butylphenol were added thereto. 100 g (0.98 mol) of triethylamine was added thereto to form an amine salt through neutralization with an acid. 20 kg of xylene was added to a separate 100 L reactor, 4.6 (47.3 moles) kg of maleic anhydride was added for 5 minutes, the reactor temperature was adjusted to 80 ° C., and 4 kg (43.0 moles) of aniline was added to the reactor for 30 minutes. Added dropwise. The resulting N-phenylmaleamic acid was transferred to a reactor with a catalyst and the reactor temperature was maintained at 140 ° C. under stirring, and the resulting water was azeotropically distilled with xylene and removed out of the system via a water separator. After the reaction was conducted for 6 hours while maintaining the temperature, the mixture was allowed to stand and cooled to 30 ° C. to separate the catalyst layer through layer separation. The xylene solution layer was transferred to a separate neutralization tank, 500 g of 5% aqueous sodium carbonate solution was added thereto, and the mixture was left for 20 minutes after stirring. The solution was cleanly separated into an organic layer and an aqueous layer and the aqueous layer was separated off. Then, 500 g of water was added thereto, stirred for 20 minutes, and left standing for 20 minutes to wash. The aqueous layer was separated off. The separated organic layer was transferred to a concentration tank, and then distilled under reduced pressure to 20 to 130 mmHg at 50 ~ 100 ℃ to remove xylene. After removal of the solvent, 7.0 kg of a light yellow solid was obtained in a concentration bath. As a result of the liquid chromatography analysis, the purity of N-phenylmaleimide was 96%, and the yield of N-phenylmaleimide was calculated to be 93% based on aniline.

Claims (18)

After adding an organic solvent, an acid catalyst, a dehydration promoter and a stabilizer to the reactor, tertiary amine and primary amine are added to amine chloride, and maleic anhydride is added to dehydrate and ring-close the reaction. A method for producing N-substituted maleimide, characterized in that azeotropic distillation together to produce N-substituted maleimide of high purity and high yield. The method of claim 1, wherein the organic solvent is 1 to 20 times the weight of the primary amine. The method of claim 2, wherein the organic solvent is at least one selected from benzene, toluene, xylene, ethylbenzene, cumene, chlorobenzene, isopropylbenzene, mesitylene, t-butylbenzene, trimethyl hexane, and octane. . The method of claim 1, wherein the acid catalyst is at least one selected from sulfuric anhydride, p-toluenesulfonic acid, orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, benzenesulfonic acid, and trichloroacetic acid. The method of claim 1, wherein the acid catalyst is used in an amount of 10 to 200 mol parts based on 100 mol parts of the primary amine. The method of claim 1, wherein the acid catalyst is supported by a carrier and added. The method of claim 6, wherein the support is 0.2 to 2 times the weight of the acid catalyst. 7. The method of claim 6, wherein the support is activated carbon, silica, silica-alumina, titanium dioxide, zirconium oxide, clay, talc, diatomaceous earth, bentonite or montmorillonite. The method of claim 1, wherein the dehydration promoter is selected from the group consisting of zinc (Zn), chromium (Cr), palladium (Pd), cobalt (Co), nickel (Ni), iron (Fe), and aluminum (Al). At least one metal oxide, metal acetate, metal maleate, metal succinate and metal chloride selected from at least one metal-containing compound. The method of claim 1, wherein the dehydration promoter is 0.005 to 0.5 mole parts with respect to 100 mole parts of primary amine. The method of claim 1, wherein the stabilizing agent is methoxybenzoquinone, p-methoxyphenol, phenothiazine, hydroquinone, alkylated diphenylamine, methylene blue, t- butylcatechol, t-butyl hydroquinone, zinc dimethyldithio At least one selected from carbamate, copper dimethyldithio carbamate, alkylphenols and alkylbisphenols. The method of claim 1, wherein the stabilizer is 0.005 to 0.5 mole parts with respect to 100 mole parts of the primary amine. The method of claim 1, wherein the primary amine is methylamine, ethylamine, n-propylamine, i-propylamine, s-propylamine, n-butylamine, s-butylamine, i-butylamine, t-butyl Amine, n-hexylamine, n-dodecylamine, allylamine, benzylamine, cyclohexylamine, aniline, ethylaniline, toluidine, hydroxyaniline, nitroaniline or ethylenediamine. The method of claim 1, wherein the input amount of the tertiary amine is 0.05 to 50 mole parts per 100 mole part of the primary amine. The method of claim 1, wherein the tertiary amine is at least one selected from trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trioctylamine and tribenzylamine. The method of claim 1, wherein the amount of maleic anhydride added is 100 to 150 mole parts with respect to 100 mole parts of primary amine. The method according to claim 1, wherein the maleic anhydride is added as needed in the middle of the reaction. The method of claim 1, wherein the reaction is carried out at 50 ~ 200 ℃.