KR102049835B1 - Method for preparing n-substituted maleimide using photocatalyst - Google Patents

Abstract

The present invention relates to a method for preparing N-substituted maleimide, and more particularly, a) preparing N-substituted maleamic acid by reacting maleic anhydride with a primary amine in the presence of an organic solvent; And b) reacting the N-substituted maleamic acid prepared in step a) with an acid catalyst, a base catalyst, and a photocatalyst to produce an N-substituted maleimide. will be.
The method for producing N-substituted maleimide according to the present invention greatly improves the purity and yield, and is applicable to mass production and various industrial fields because the entire process is simple and industrially useful.

Description

Method for producing N-substituted maleimide using photocatalyst {METHOD FOR PREPARING N-SUBSTITUTED MALEIMIDE USING PHOTOCATALYST}

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

N-substituted maleimides are compounds useful as raw materials or intermediates for synthetic resins, pharmaceuticals, pesticides, dyes and the like. In particular, Acrylonitrile-Butadiene-Styrene (ABS) resins, Acrylonitrile-Styrene (AS) resins, Acrylonitrile-Chorinated polyethylene-Styrene; Styrene-based resins such as ACS) resins, acrylonitrile-ethylene propylene-rubber-styrene (AES) resins, acrylonitrile-acrylate-styrene (AAS) resins In order to improve heat resistance of vinyl chloride resin, (meth) acrylate resin, and phenol resin, it is widely used as one of copolymerization components. Among them, N-phenyl maleimide (N-Phenyl Maleimide; PMI) is widely used because of its excellent reactivity and heat resistance.

Preparation of N-substituted maleimide is obtained by dehydrating maleic anhydride and primary amine by dehydration reaction, by producing N-substituted maleamic acid from maleic anhydride and primary amine, and dehydrating and immobilizing it. Many methods are known conventionally, such as the method of obtaining by imidation through the ring-closure reaction of a maleamic acid monoester. Among the various methods, the method through the dehydration reaction of maleic anhydride and the primary amine has a problem that the yield is low, the productivity is lowered. In addition, the method obtained from the maleamic acid monoester has a problem that the alcohol generated during the ring-closure reaction remains in the product, such as mixing, so that the quality of the final product is greatly reduced, it is not commercially suitable.

Therefore, industrially, the method of producing by imidating N-substituted maleamic acid produced | generated from maleic anhydride and a primary amine by a dehydration ring reaction is used industrially. Accordingly, various techniques have been proposed to improve the yield and purity of N-substituted maleimide prepared through the above method.

As an example, US Pat. No. 2,444,536 discloses a method for dehydrating N-substitutions using a dehydrating agent such as acetic anhydride in the presence of a sodium acetate catalyst. This method provides a relatively high reaction yield, but it is difficult to apply to mass production due to the high production cost due to the use of a large amount of expensive dehydrating agent and the complicated purification process of the final product after the reaction.

On the other hand, US Patent No. 3,431,276 is a water produced by heating, dehydrating and ring-closure N-substituted maleamic acid using an acid catalyst such as sulfur trioxide, sulfuric acid, orthophosphoric acid in a solvent having a suitable boiling point without using a chemical dehydrating agent It is proposed to prepare an N-substituted maleimide by azeotropic distillation with a solvent to remove out of the system. This method does not require a dehydrating agent and has the advantage of easily separating the produced N-substituted maleimide, but the reaction yield is not high, and there is a problem of easily involving side reactions.

In addition, Japanese Unexamined Patent Publication No. 1982-042700, after the production of N-substituted maleamic acid, using aprotic polar solvent such as dimethylformamide or dimethyl sulfoxide to increase the solubility of N-substituted maleamic acid, A method for obtaining N-substituted maleimide by dehydrating in the presence of a catalyst is shown. This method requires a separate dehydrating agent to remove the water generated during the reaction, and the cost of the solvent used is expensive and toxic.

In addition, Korean Patent Publication No. 2009-0074982 discloses N-substituted maleamic acid by reacting maleic anhydride with a primary amine, and then additionally adds maleic anhydride together with an acid catalyst to the prepared N-substituted maleamic acid. By imidation, a method of increasing the purity and yield of N-substituted maleimide is proposed. This method has a problem that a large amount of maleic anhydride is used and can cause side reactions.

These patents have improved the yield, purity, reaction time, and the like of N-substituted maleimide to some extent compared to the existing manufacturing method, but the effect is insufficient. In addition, 2-amino-N-substituted succinimide, a by-product that is inevitably produced during the reaction, carbonizes the surface of the polymer compound in which N-substituted maleimide is used or the final product. Because of the problem of irregularities on the surface of the must be removed. However, in the case of the conventional manufacturing method, it is difficult to remove 2-amino-N-substituted succinimide, which is not only limited to the application field but also requires a separate purification process, which requires a lot of time and cost. Therefore, there is a need for further research on a method for preparing N-substituted maleimide having excellent yield and quality through a simple and efficient process.

US Patent No. 2,444,536 (1948.07.06), SYNTHESIS OF N-ARYL-MALEIMIDES U.S. Patent No. 3,431,276 (1969.03.04), PROCESS FOR PRODUCING IMIDE DERIVATIVES Japanese Patent Laid-Open No. 1982-042700 (1982.03.10), 9-DIHYDROMYCINAMICIN 3 Republic of Korea Patent Publication No. 2009-0074982 (2009.07.08), Method of manufacturing N-substituted maleimide

Accordingly, the present inventors have conducted various studies to solve the above problems. As a result, when an acid catalyst, a base catalyst, and a photocatalyst are simultaneously used in the production of N-substituted maleimide, the by-products generated during synthesis are simplified while simplifying the reaction under mild conditions. The present invention was completed by confirming that the production of N-substituted maleimide can be improved by effectively inhibiting the production of N-substituted maleimide.

Accordingly, an object of the present invention is to provide a method for preparing N-substituted maleimide, which can realize higher yield and purity than conventional methods.

In order to achieve the above object, the present invention comprises the steps of: a) preparing an N-substituted maleamic acid of Formula 2 by reacting maleic anhydride of Formula 3 with a primary amine in the presence of an organic solvent; And b) reacting the N-substituted maleamic acid of Formula 2 prepared in step a) with a catalyst to produce an N-substituted maleimide of Formula 1; wherein the catalyst comprises an acid catalyst, a base catalyst, and Provided is a process for preparing N-substituted maleimide comprising a photocatalyst:

Scheme 1

(In Scheme 1, R is as described in the specification.)

The photocatalyst may include titanium dioxide.

In this case, the photocatalyst may have an average particle diameter of 10 to 500 nm, and may have optical activity with respect to light in a wavelength range of 380 to 750 nm.

In this case, the photocatalyst may be added at 0.01 to 0.1 mole relative to 1 mole of the primary amine.

The primary amine is methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, s-butylamine, i-butylamine, t-butylamine, n-hexylamine, n-octylamine, It may include one or more selected from the group consisting of n-decylamine, n-dodecylamine, cyclohexylamine and aniline.

The acid catalyst may include one or more selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, acetic acid, trichloracetic acid, cresolsulfonic acid, toluenesulfonic acid, benzenesulfonic acid, methane sulfonic acid and trifluoromethanesulfonic acid.

The base catalyst may include one or more selected from the group consisting of diethylamine, dimethylphenylamine, diethylphenylamine, triethylamine, tripropylamine, tributylamine, trihexylamine and pyridine.

The molar ratio of the acid catalyst, base catalyst and photocatalyst may be 0.01: 0.01: 0.01 to 1: 5: 0.1.

In the method of preparing N-substituted maleimide according to the present invention, an acid catalyst, a base catalyst, and a photocatalyst are used together to improve the reaction efficiency and the reaction rate through the acid catalyst and the base catalyst, together with the effect of the photocatalyst. The yield and purity of the N-substituted maleimide, which is the final product, is improved by securing the production control effect. In addition, by using three kinds of catalysts simultaneously, a simple reaction under mild conditions can be produced in high yield and purity, and can be mass-produced.

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

The terms or words used in this specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best describe their invention. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

As used herein, "high yield" means having a yield of at least 80%, preferably at least 85%, unless otherwise specified.

As used herein, "high purity" means having a purity of at least 90%, preferably at least 95%, unless otherwise specified.

The present invention relates to a process for preparing N-substituted maleimide of high purity and high yield.

Conventional methods for producing N-substituted maleimide have low yields and complex processes, making them unsuitable for industrial use in terms of productivity, process efficiency and economics. In addition, a certain compound is used excessively or the reaction proceeds under severe conditions of high temperature and high pressure, requiring a lot of time and cost, and side reactions occur easily, yields are lowered, and the purification and purification process of the product are complicated and inefficient, resulting in low purity. . In addition, as described above, the remaining and by-products of 2-amino-N-substituted succinimide which are inevitably generated in the reaction process remain.

Accordingly, the present invention provides a method for preparing N-substituted maleimide that exhibits high yield and purity by using three catalysts together to simplify the reaction while improving reaction rate and efficiency and suppressing the production of by-products.

A method for preparing N-substituted maleimide according to one embodiment of the present invention is represented by the following Scheme 1. Specifically, a) N-substituted compound of Formula 2 by reacting maleic anhydride of Formula 3 with a primary amine in the presence of an organic solvent. Preparing a maleamic acid; And b) reacting the N-substituted maleamic acid of Formula 2 prepared in step a) with a catalyst to produce an N-substituted maleimide of Formula 1, wherein the catalyst is an acid catalyst, a base catalyst And photocatalysts:

Scheme 1

(In Scheme 1,

R is an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms.).

The term "alkyl group" used in the present invention may be straight or branched chain, carbon number is not particularly limited, but is preferably 1 to 20, specifically 1 to 10. Specific examples include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl, hexyl, heptyl, and the like.

The term "alkoxy group" as used herein refers to an alkyl group having 1 to 20 carbon atoms having an oxygen atom through an ether bond at the end of the carbon chain unless otherwise specified, but is not limited thereto.

As used herein, the term "cycloalkyl group" means a non-aromatic carbon-based ring of at least three carbon atoms. The cycloalkyl group includes, but is not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like.

As used herein, the term "aryl group" means a single or multiple aromatic carbon-based ring having 6 to 20 carbon atoms. The aryl group includes a phenyl group, a biphenyl group, a fluorene group, and the like, but is not limited thereto.

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

First, step a) reacts maleic anhydride of Formula 3 with a primary amine in the presence of an organic solvent to prepare N-substituted maleamic acid of Formula 2.

Maleic anhydride used in the present invention is a compound having the same structure as in Chemical Formula 3 in which one molecule of water is removed from maleic acid, and is one of the starting materials for preparing N-substituted maleimide.

The maleic anhydride may be directly synthesized through a method commonly performed in the art or purchased and commercially available products.

The maleic anhydride may be used in an amount of 0.5 to 1.5 mol, preferably 0.8 to 1.2 mol relative to 1 mol of the primary amine described later. When the maleic anhydride is used below the molar ratio, there is a problem that the reaction does not proceed smoothly. On the contrary, when the maleic anhydride is exceeded, the yield decreases and an unreacted maleic anhydride is excessively left after the completion of the reaction. This is uneconomical because it is necessary.

The primary amine used in the present invention generates an N-substituted maleamic acid of formula (2) which is an intermediate product through the dehydration reaction with maleic anhydride described above. The primary amine is R-NH ₂ as shown in Scheme 1, wherein the substituent of the final N-substituted maleimide is changed depending on the substituent R.

Preferably, R may be an alkyl group having 1 to 15 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an aryl group having 6 to 15 carbon atoms. More preferably, R may be an alkyl group having 3 to 10 carbon atoms or an aryl group having 6 to 12 carbon atoms.

The kind of the primary amine is not particularly limited, and for example, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, s-butylamine, i-butylamine, t-butylamine, It may include one or more selected from the group consisting of n-hexylamine, n-octylamine, n-decylamine, n-dodecylamine, cyclohexylamine and aniline. Preferably one selected from the group consisting of methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, s-butylamine, i-butylamine, t-butylamine, cyclohexylamine and aniline It may be abnormal.

The organic solvent used in the present invention is a nonpolar solvent, insoluble or immiscible in water, inert in the reaction and should not participate. In addition, a solvent having a boiling point of 50 to 170 ° C. may be used so that the reaction proceeds smoothly and can be easily removed after the completion of the reaction. The organic solvent should be determined in consideration of process conditions, raw materials, solubility, price, and ease of handling of the product. For example, benzene, toluene, xylene, ethylbenzene, i-propylbenzene, chlorobenzene, dichlorobenzene, and at least one selected from the group consisting of t-butylbenzene, trimethylbenzene, trimethylhexane, oxane, 4-isopropyltoluene, tetrahydronaphthalene and cyclohexylbenzene. Preferably it may be at least one selected from the group consisting of toluene and xylene.

The organic solvent may be used in an amount of 2 to 20 vols, preferably 5 to 15 vols, and more preferably 8 to 15 vols, based on the primary amine described above. If the organic solvent is used in less than the above range, the reaction is not sufficient, on the contrary, if the organic solvent exceeds the above range, excess energy is consumed in the process of removing the solvent, thereby lowering economic efficiency and productivity. Can cause problems.

Subsequently, step b) reacts the N-substituted maleamic acid of Formula 2 prepared in step a) with a catalyst to prepare an N-substituted maleimide of Formula 1.

The catalyst used in the present invention serves to prepare an N-substituted maleimide of Formula 1 by imidizing the N-substituted maleamic acid of Formula 2 through a dehydration ring reaction. In this case, the catalyst includes an acid catalyst, a base catalyst and a photocatalyst. In particular, by using the acid catalyst, base catalyst and photocatalyst together, the present invention can solve the problems such as excessive input, dehydrating agent use, side reactions and the like caused when using the acid catalyst or the base catalyst alone. In addition, by using the three catalysts in a certain ratio, it is possible to improve the yield and purity by improving the reaction efficiency and speed.

The acid catalyst is used as a main catalyst to dehydrate the N-substituted maleamic acid prepared in step a) to proceed with imidization to prepare N-substituted maleimide of Chemical Formula 1.

The acid catalyst may be at least one selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, acetic acid, trichloracetic acid, cresolsulfonic acid, toluenesulfonic acid, benzenesulfonic acid, methanesulfonic acid and trifluoromethanesulfonic acid. Preferably, at least one selected from the group consisting of sulfuric acid, hydrochloric acid, acetic acid, toluenesulfonic acid and methanesulfonic acid can be used.

The acid catalyst may be used in an amount of 0.01 to 1.0 mole, preferably 0.1 to 1.0 mole relative to 1 mole of the primary amine used in step a). When the acid catalyst is used below the molar ratio, there is a problem that a smooth reaction does not proceed. On the contrary, when the acid catalyst exceeds the molar ratio, the yield may be lowered by lowering the reaction activity and advancing side reactions of the catalyst.

The base catalyst serves to promote the reaction activity of the above-described acid catalyst as a first cocatalyst.

An amine compound may be used as the base catalyst, and is not particularly limited. For example, the base catalyst may include one or more selected from the group consisting of diethylamine, dimethylphenylamine, diethylphenylamine, triethylamine, tripropylamine, tributylamine, trihexylamine and pyridine. have. Preferably it may be at least one selected from the group consisting of diethylamine, dimethylphenylamine, diethylphenylamine, triethylamine and tripropylamine. More preferably, it may be at least one selected from the group consisting of diethylamine, dimethylphenylamine and diethylphenylamine.

The base catalyst may be used in an amount of 0.01 to 1.0 mole, preferably 0.05 to 0.5 mole relative to 1 mole of the primary amine used in step a). When the base catalyst is used in less than the molar ratio, it is not possible to obtain a sufficient reaction promoting effect, on the contrary, when the molar ratio is exceeded, a problem may occur that reduces the reaction activity of the acid catalyst as the main catalyst.

The photocatalyst is a second cocatalyst, which serves to minimize the production of 2-amino-N-substituted succinimide which is a byproduct generated during the reaction. Specifically, the movement of electrons occurs in the catalyst by receiving light energy, and the moved electrons activate the amine group of the produced intermediate product to promote the cyclization reaction, and thus the reaction rate to the N-substituted maleimide rather than the reaction rate to the byproduct. It plays a role of increasing significantly, and even if a small amount of by-products is generated, the charge to the photocatalyst promotes the decomposition reaction of the substituted aniline through the movement to the by-products, thereby inhibiting the formation of by-products.

The photocatalyst may include titanium dioxide (TiO ₂ ). The titanium dioxide may be an anatase type, a brookite type or a rutile type crystal. In view of photocatalytic activity, the titanium dioxide of the present invention is preferably an anatase type crystal.

In this case, the photocatalyst may have an average particle diameter of 10 to 500 nm, preferably 50 to 300 nm. When the average particle diameter of the photocatalyst is less than the above range, a byproduct formation inhibitory effect cannot be obtained. On the contrary, when the average particle diameter exceeds the above range, the reaction activity of the photocatalyst itself is not only lowered but also adversely affects the activity of the acid or base catalyst used together. Can be.

The photocatalyst has photoactivity to light in a wavelength range of 350 to 750 nm, and the step b) may proceed by irradiating light in the wavelength range.

The photocatalyst may be used in an amount of 0.01 to 0.1 moles, preferably 0.05 to 0.1 moles relative to 1 mole of the primary amine used in step a). When the photocatalyst is used at less than the molar ratio, a byproduct formation inhibitory effect may not be obtained. On the contrary, when the photocatalyst is exceeded, a problem of lowering the reaction activity of the acid catalyst as the main catalyst may occur.

The molar ratio of the acid catalyst, base catalyst and photocatalyst used in step b) of the present invention may be 0.01: 0.01: 0.01 to 1: 5: 0.1, preferably 0.05: 0.05: 0.05 to 0.1: 0.1: 0.1. When the molar ratio of the three catalysts falls within the above range, by-product generation may be minimized to prepare high purity N-substituted maleimide.

In addition, the reaction may be carried out by further adding a polymerization inhibitor in step b).

The polymerization inhibitor is methoxybenzoquinone, hydroquinone, t-butyl hydroquinone, p-methoxyphenol, t-butylcatechol, alkyldiphenylamine, phenothiazine, methylene blue, mercaptobenzimidazole, zinc dimethyldithio Carbamate, copper dimethyldithiocarbamate, copperdibutyldithiocarbamate, distearyl-3,3'-thiodipropionic acid ester and triphenyl phosphite Can be. Preferably it may be at least one selected from the group consisting of methoxybenzoquinone, hydroquinone, t-butyl hydroquinone and phenothiazine.

The polymerization inhibitor may be used in an amount of 0.001 to 0.5 moles, preferably 0.005 to 0.3 moles relative to 1 mole of the primary amine used in step a). When the polymerization inhibitor is used in the molar ratio of obesity, there is a problem that a maleimide polymer is formed due to insufficient stabilization effect, and on the contrary, when the molar ratio is exceeded, it may adversely affect the formation of a polymer compound when used as a monomer for resin formation. have.

In the production method according to an embodiment of the present invention, the reaction temperature for each step may vary depending on conditions. In one example, step a) may be carried out at a temperature of 15 to 95 ℃, step b) may be carried out at a temperature of 50 to 200 ℃. In the present invention, the reaction pressure may also vary depending on the reaction conditions in each step. The reaction pressure is not particularly limited but may be widely selected from reduced pressure, atmospheric pressure and pressure. In addition, the reaction time for each step also varies depending on conditions such as the type of solvent, the amount of starting material, the amount of catalyst used, the reaction temperature, and the like, and may generally range from 0.5 to 15 hours.

In addition, the product obtained from the above-mentioned step is subjected to purification to obtain an N-substituted maleimide of the formula (1).

The purification is for removing unreacted substances and reaction by-products, and is not particularly limited in the present invention, it is possible to process commonly used in the art.

The product obtained from the steps a) and b) described before the purification comprises water, which is removed via azeotropic distillation.

As described above, the purification may use a variety of known methods. In one example, any one of simple distillation, fractional distillation, azeotropic distillation, vacuum distillation, recrystallization, extraction, sublimation or chromatography may be used.

In addition, base or activated carbon may be used in the purification.

In this case, the base may include one or more selected from the group consisting of sodium carbonate, sodium bicarbonate, ammonium hydroxide, ammonia, sodium phosphate and sodium sulfate. Preferably the base may be at least one selected from the group consisting of sodium carbonate, sodium bicarbonate and ammonium hydroxide.

In this case, the activated carbon may be used as an adsorbent, without particular limitation, as long as it is generally used for purification. The activated carbon may generally be prepared from various carbonaceous source materials such as wood, sawdust, nut husks, palm husks, lignite, coal, petroleum pitch, and the like. The activated carbon may be plant-based activated carbon, coal-based activated carbon, or petroleum-based activated carbon. In addition, the form of the activated carbon is not particularly limited, but may be crushed, powdery, granular or fibrous, preferably powdery or granular.

The activated carbon includes a plurality of pores inside and outside, the average pore size of the pores is 0.1 to 50 ㎛, porosity or porosity may be 10 to 90% of the total volume of the activated carbon. In addition, the specific surface area of the activated carbon may be 100 to 3000 m 2 / g.

When using the activated carbon in the reaction can be carried out through a variety of methods known in the art, for example, it can be carried out directly by using activated carbon or using a column packed with activated carbon (packing).

The reaction time and the reaction temperature in the purification may vary depending on the process conditions and are not particularly limited. For example, the reaction time may be 1 to 10 hours, and the reaction temperature may be 20 to 70 ° C.

N-substituted maleimide prepared according to the production method of the present invention is N-methyl maleimide, N-ethyl maleimide, Nn-propyl maleimide, N-isopropyl maleimide, Nn-butyl maleimide, Ns-maleimide Id, Nt-maleimide, Nn-hexyl maleimide, Nn-dodecyl maleimide, N-allyl maleimide, N-benzyl maleimide, N-cyclohexyl maleimide, N-phenylmaleimide, N-nitro phenyl maleimide Mid, N-hydroxy group maleimide, N-methoxy maleimide, N-ethoxy maleimide, N-monochromophenyl maleimide, N-dichlorophenyl maleimide, N-monomethyl phenyl maleimide, N-dimethylphenyl Maleimide, N-ethylphenyl maleimide, and the like.

The manufacturing method of N-substituted maleimide of this invention has the following advantages compared with the conventional manufacturing method.

First, by using an acid catalyst, a base catalyst, and a photocatalyst in combination with imidization of N-substituted maleamic acid, N-substitution with high productivity is achieved by maximizing the reaction activity of the catalyst and minimizing the generation of by-products. Provided is a method for preparing maleimide.

Secondly, the method for preparing N-substituted maleimide according to the present invention starting from maleic anhydride can realize excellent yield and purity through a simple reaction under milder conditions than before, and is suitable for commercial mass production with excellent economic efficiency and productivity. And industrially applicable to various fields.

At this time, the yield of N-substituted maleimide according to the production method of the present invention may be 80% or more, purity 90% or more.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention in more detail, it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples in accordance with the gist of the present invention. .

Example  And Comparative example N-phenyl Maleimide  Produce

Example 1

Into a 1.0L reactor, 40 g (0.4 mol) of maleic anhydride and 400 ml of toluene were added and stirred for 10 to 15 minutes to completely dissolve maleic anhydride. Then, 36 ml (0.4 mol) of aniline was added over 20 to 25 minutes. The reaction was conducted at room temperature for 1 hour to synthesize N-phenyl maleamic acid.

Then, sulfuric acid 4.1 g (0.04 mol) and diethylamine 4.0 g (0.04 mol), titanium oxide to the reactor (average particle size: 200 ㎚) 3.2 g (0.04 mol), phenothiazine, ^{40 mg (16.0 × 10 - 5} mol ) And irradiated with 350 ~ 750 nm light for 6 hours at 120 ℃. At this time, the produced water was removed through azeotropic distillation.

The reactor in which the toluene solution layer remained was cooled to 30 ° C., 40 ml of a 1 M sodium carbonate aqueous solution was added thereto, and stirred at room temperature for 2 hours. The stirring was stopped and the reaction solution was transferred to another 1.0 L reactor, 40 ml of water was added thereto, followed by stirring for 2 hours to sufficiently remove sodium carbonate. At this time, the solution is separated into an organic layer and an aqueous layer, and after separating only the organic layer, 4 g of activated carbon (10 wt% based on the weight of aniline) was added, stirred for 1 hour, filtered, and the organic layer was separated again. The separated organic layer was distilled under reduced pressure at 130 mmHg, 60 ° C. to remove toluene to obtain a yellow N-phenyl maleimide solid.

Example 2

Proceed in the same manner as in Example 1, except that titanium oxide having an average particle diameter of 100 nm was carried out in the same manner as in Example 1 to obtain N-phenyl maleimide.

Example 3

Proceed in the same manner as in Example 1, except that 1.5 g (0.02 mol) of titanium oxide was used in the same manner as in Example 1 to obtain N-phenyl maleimide.

Example 4

Proceed in the same manner as in Example 1, except that 8.2 g (0.08 mol) of sulfuric acid and 8.1 g (0.08 mol) of diethylamine were used to obtain N-phenyl maleimide. It was.

Comparative Example 1

Proceed in the same manner as in Example 1, except that the photocatalyst was not used to perform the same as in Example 1 to obtain N-phenyl maleimide.

Comparative Example 2

Proceed in the same manner as in Example 1, except that only 0.32 g (0.004 mol) of titanium oxide (average particle diameter: 200 nm) was carried out in the same manner as in Example 1 to obtain N-phenyl maleimide.

Experimental Example  1. Final Product Analysis

The yield of N-phenyl maleimide prepared in the above Examples and Comparative Examples was calculated based on the aniline used. In addition, in order to analyze the purity of N-phenyl maleimide and the yield of 2-amino-N-substituted succinimide obtained from the above Examples and Comparative Examples, 0.1 g of N-phenyl maleimide solid content was dissolved in 4.0 ml of a mobile phase, followed by the following conditions. According to the analysis using high performance liquid chromatography (HPLC), the results obtained are shown in Table 1 below.

[HPLC Analysis Conditions]

Column: C18 column (Zorbax XDB-C18 4.6 x 250 mm, Agilent, USA)

Detector: ultraviolet absorbance photometer (wavelength 254 nm)

Flow rate: 1.0 mL / min

Injection volume: 10 μl

Column temperature: 20 ~ 30 ℃

Mobile phase: 0.1% aqueous solution of phosphoric acid: acetonitrile = 50%: 50%

2-amino-N-substituted succinimide production rate
(%) N-phenyl maleimide purity
(%) Example 1 0 99.6 Example 2 0 99.6 Example 3 0 99.6 Example 4 0 99.5 Comparative Example 1 7.5 91 Comparative Example 2 4.3 94

The embodiment according to the present invention effectively inhibits the production of the necessary side reactions which have the greatest effect on the polymerization and properties when applied to the polymer composition and the quality of the final product compared to Comparative Examples 1 and 2 without the use of photocatalysts or in small amounts. It can be seen that the purity of the N-phenyl maleimide is improved.

In the method for producing N-substituted maleimide according to the present invention, N-substituted maleimide can be produced in high yield and purity using three kinds of catalysts, thereby enabling mass production of N-substituted maleimide, Enable the application.

Claims (9)

As shown in Scheme 1 below,
a) reacting maleic anhydride of Formula 3 with a primary amine in the presence of an organic solvent to prepare an N-substituted maleamic acid of Formula 2; And
b) reacting the N-substituted maleamic acid of Chemical Formula 2 prepared in step a) with a catalyst to prepare N-substituted maleimide of Chemical Formula 1;
The catalyst comprises an acid catalyst, a base catalyst and a photocatalyst,
The photocatalyst comprises titanium dioxide, and a method for producing N-substituted maleimide containing 0.05 to 0.1 mole relative to 1 mole of the primary amine:
Scheme 1

(In Scheme 1,
R is an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms.). delete The method of claim 1,
The photocatalyst has an average particle diameter of 10 to 500 nm, a method for producing N-substituted maleimide. The method of claim 1,
The photocatalyst has a photoactivity for light in the wavelength range of 380 to 750 nm, a method for producing N-substituted maleimide. delete The method of claim 1,
The primary amine is methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, s-butylamine, i-butylamine, t-butylamine, n-hexylamine, n-octylamine, The manufacturing method of N-substituted maleimide containing 1 or more types chosen from the group which consists of n-decylamine, n-dodecylamine, cyclohexylamine, and aniline. The method of claim 1,
The acid catalyst is N-substituted maleimide containing one or more selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, acetic acid, trichloracetic acid, cresolsulfonic acid, toluenesulfonic acid, benzenesulfonic acid, methane sulfonic acid and trifluoromethanesulfonic acid Manufacturing method. The method of claim 1,
The base catalyst is N-substituted Malay containing at least one selected from the group consisting of diethylamine, dimethylphenylamine, diethylphenylamine, triethylamine, tripropylamine, tributylamine, trihexylamine and pyridine Method for preparing mead. The method of claim 1,
The molar ratio of the acid catalyst, base catalyst and photocatalyst is 0.01: 0.01: 0.01 to 1: 5: 0.1, the production method of N-substituted maleimide.