JP5032448B2 - Process for producing N-substituted maleimides - Google Patents

Description

  The present invention relates to a method for producing high-purity N-substituted maleimides in high yield, and more specifically, by reacting maleic anhydride with primary amines to produce N-substituted maleimides. Using a supported catalyst having a melting point of 150 ° C. or higher and an N-substituted maleimide to be produced and an organic phosphonic acid that is insoluble on a solid support, and generating side reactions. The present invention relates to a method for producing high-purity N-substituted maleimides in a high yield.

  N-substituted maleimides are compounds widely used for copolymer monomers, agricultural chemicals, and pharmaceutical intermediates for improving heat resistance such as ABS, PVC, PS, PMMA, and SAN resin.

  Methods for producing N-substituted maleimides have been studied for a long time, and various methods are known. In general, the synthesis reaction of N-substituted maleimides involves the production of N-substituted maleamic acid as an intermediate through the reaction of maleic anhydride and primary amines to produce N-substituted maleamic acid. In this method, N-substituted maleimides are synthesized through a dehydration ring-closing reaction, and the synthesized N-substituted maleimides are separated and purified in a reaction solution to produce N-substituted maleimides.

  US Pat. No. 2,444,536 proposes a chemical dehydration ring-closing reaction method in which maleimides are produced through a reaction of dehydrating and ring-closing N-substituted maleamic acid using acetic anhydride as a dehydrating agent. However, the method for producing N-substituted maleimides through a chemical dehydration ring-closing reaction using a dehydrating agent must use an expensive dehydrating agent in an amount equal to or more than the N-substituted maleimide to be produced. It is difficult to separate the produced N-substituted maleimides from the reaction solution, and it is difficult to apply them commercially.

  In US Pat. No. 3,431,276 and British Patent No. 1,041,027, a chemical dehydrating agent is not used, but in a solvent having a boiling point of 80 ° C. or higher, such as toluene, xylene, or chlorobenzene, A method for producing N-substituted maleimides using orthophosphoric acid, sulfuric acid or the like as an acid catalyst has been proposed. Even though the proposed method does not use expensive dehydrating agents and has the advantage that the produced N-substituted maleimides can be easily separated from the reaction solution, the yield is low and the by-product is high due to the high reaction temperature. There is a disadvantage that a large amount is generated.

  U.S. Pat. Nos. 4,623,734 and 4,786,738 use a solvent capable of azeotropic distillation with water at a reaction temperature of 120-170 [deg.] C., such as benzene, toluene, ethylbenzene, xylene and the like. In synthesizing N-substituted maleimides under an acid catalyst, a metal-containing compound such as zinc acetate and a stabilizer such as copper dibutyldithiocarbamate are used to synthesize N-substituted maleimides in high yield. A way to do it is presented.

  In U.S. Pat. No. 4,851,547, in the synthesis of N-substituted maleimides, an acid such as sulfuric acid, p-toluenesulfonic acid, orthophosphoric acid and the like are used as raw materials used in the synthesis of N-substituted maleimides. A method is proposed in which an amine salt obtained by neutralization with one amine or an amine salt supported on a support such as synthetic silica or diatomaceous earth is used as a catalyst.

  However, the methods for synthesizing N-substituted maleimides provided in the above-mentioned US Pat. Nos. 4,623,734, 4,786,738, and 4,851,547 are effective for side reactions. No suppression method is presented, and this method is not suitable for synthesizing highly pure N-substituted maleimides having a purity of 96% or more.

  In U.S. Pat. No. 4,980,483, during the synthesis of N-substituted maleimides, in order to suppress the formation of fumaric acid which is a by-product generated through side reactions, After the middle of the reaction so that the molar ratio of maleic anhydride is less than 1, the molar ratio of the total amount of maleic anhydride added to the reaction system to the total amount of primary amines added to the reaction system is 1 A method for producing N-substituted maleimides by performing a synthesis reaction so as to exceed the above is proposed. However, there is no method for suppressing by-products other than fumaric acid produced during the reaction, and there is a problem that it is difficult to synthesize highly pure N-substituted maleimides having a purity of 96% or more.

  US Pat. No. 5,068,357 uses a mixed solvent consisting of a solvent capable of azeotropic distillation with water and an organic aprotic polar solvent for the production of N-substituted maleimides, and uses metallic tin as a catalyst. A method for synthesizing N-substituted maleimides through a dehydration ring-closing reaction using a tin compound such as tin oxide and N-substituted maleic acid tin salt has been proposed. By using a tin compound that is not an acid catalyst such as sulfuric acid or orthophosphoric acid as a catalyst, the corrosion problem of the reactor can be effectively prevented, but the dehydration ring-closing reaction of N-substituted maleamic acid is sufficiently high. There is a problem that a large amount of N-substituted maleamic acid remains in the finally formed N-substituted maleimide, which is not achieved in a yield.

  Most of the prior art uses acid catalysts such as orthophosphoric acid and sulfuric acid. These acid catalysts exist in liquid form at the synthesis reaction temperature of N-substituted maleimides, and the reaction product is maleic anhydride. , Primary amines, and N-substituted maleimides, which are the products, are mixed well, and a large amount of reactants and products dissolve on the catalyst during the synthesis reaction, causing numerous side reactions. There is a point.

The above prior art is a method suitable for commercially synthesizing N-substituted maleimides. However, high-purity N-substituted maleimides having a purity of 95% or more are obtained in a high yield of 95% or more. No way to synthesize is presented.
US Pat. No. 2,444,536 US Pat. No. 3,431,276 British Patent No. 1,041,027 US Pat. No. 4,623,734 U.S. Pat. No. 4,786,738 US Pat. No. 4,851,547 US Pat. No. 4,623,734 U.S. Pat. No. 4,786,738 US Pat. No. 4,851,547 US Pat. No. 4,980,483 US Pat. No. 5,068,357

  In order to solve the above-mentioned problems of the prior art, the present invention provides an organic phosphonic acid having a melting point of 150 ° C. or higher and insoluble with the N-substituted maleimide to be produced during the synthesis of N-substituted maleimides. An object of the present invention is to provide a method for synthesizing and producing high-purity N-substituted maleimides in a high yield by using a supported catalyst supported on a solid support, suppressing the occurrence of side reactions.

  The above and other objects of the present invention can be achieved by the present invention described below.

  In order to achieve the above object, the present invention provides a method for producing N-substituted maleimides, which is an organic solvent that can be azeotropically distilled with water, has a melting point of 150 ° C. or higher, and is insoluble with the N-substituted maleimide to be produced. In the presence of a supported catalyst in which an organic phosphonic acid is supported on a solid support, primary amines and maleic anhydride are administered, and high purity N-substituted maleimides are increased through a dehydration ring closure reaction at 100 to 140 ° C. Provided is a method for producing N-substituted maleimides, characterized in that it is synthesized and produced in a yield.

  Hereinafter, the present invention will be described in detail.

  In the method for producing N-substituted maleimides of the present invention, an organic solvent which can be azeotropically distilled with water, an N-substituted maleimide having a melting point of 150 ° C. or more and an organic phosphonic acid which is insoluble in the solid support. In this method, primary amines and maleic anhydride are administered in the presence of a supported catalyst and N-substituted maleimides are produced through a dehydration ring closure reaction at 100 to 140 ° C.

  N-substituted maleimides that can be synthesized through the present invention include N-methylmaleimide, N-ethylmaleimide, N- (n-propyl) maleimide, N-isopropylmaleimide, N- (n-butyl) maleimide, N- (sec -Butyl) maleimide, N- (iso-butyl) maleimide, N- (tert-butyl) maleimide, N- (n-hexyl) maleimide, N- (n-octyl) maleimide, N- (n-decyl) maleimide, N- (n-dodecyl) maleimide, N-cyclohexylmaleimide, N-phenylmaleimide and the like can be mentioned.

  In the present invention, the maleic anhydride is preferably used in a molar ratio of 1.0 to 1.1 with respect to the primary amine used during the synthesis of the N-substituted maleimides. When maleic anhydride is used in less than 1.0 molar ratio, problems of yield reduction and by-product increase occur. When used in a 1.1 molar ratio or more, a large amount of unreacted maleic anhydride remains after the synthesis of the N-substituted maleimide, which is not preferable in terms of economy.

  The organic solvent used in the present invention is preferably a nonpolar solvent that can be azeotropically distilled with water, but preferably has a boiling point of 80 to 160 ° C. Examples thereof include benzene, toluene, xylene, ethylbenzene, isopropyl Examples include benzene, cumene, mesitylene, chlorobenzene, ethylcyclohexane, dichlorobenzene, dodecane, nonane, and trimethylhexane.

  The organic solvent is preferably used in an amount of 2 to 10 times by weight with respect to the primary amines used in the synthesis of the N-substituted maleimide. When the amount of the organic solvent used is less than 2 times by weight, it is not easy to effectively remove water produced from the reaction system through the dehydration ring-closing reaction of N-substituted maleamic acid, resulting in a problem that the yield decreases. If the amount exceeds 10 times by weight, a large amount of energy is consumed in the process of separating the solvent from the synthesized N-substituted maleimide solution, which is not preferable from an economical viewpoint.

  The primary amines used in the present invention are methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, sec-butylamine, iso-butylamine, tert-butylamine, n-hexylamine, n-octylamine. , N-decylamine, n-dodecylamine, cyclohexylamine, aniline and the like.

  The catalyst used in the present invention is preferably a supported catalyst in which an organic phosphonic acid having a melting point of 150 ° C. or higher and an organic phosphonic acid that is insoluble with the N-substituted maleimide to be produced is supported on a solid support. 2-phosphonobutane-1,2,4-tricarboxylic acid, 2-hydroxy phosphonoacetic acid, aminotrimethylene phosphonic acid (amino) tri (methylene) phosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, bis (hexamethylene) triamine penta (methylene) phosphonic acid), ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid ine penta (methylene) phosphonic acid).

  The catalyst is preferably used by being supported on a solid support. Since the catalyst has a melting point of 150 ° C. or higher, when used without being supported on a support, it exists in a solid state at normal temperature and N-substituted maleimide synthesis reaction temperature, and its surface area is greatly reduced, yield. This causes a problem of a significant drop.

The solid support preferably has a surface area of 100 m ² / g or more. Examples thereof include diatomaceous earth, zirconium oxide, silica, silica-alumina, titanium dioxide, activated carbon, clay, and montmorillonite.

  The catalyst is used in an amount of 0.1 to 1.0 molar ratio based on the phosphonic acid contained in the catalyst molecule, based on the primary amines used in the synthesis of the N-substituted maleimides. It is preferable to do. If the amount used is less than 0.1 molar ratio, a problem that the yield decreases occurs, and if it exceeds 1.0 molar ratio, there is no further yield improvement effect, which is preferable from an economical viewpoint. Absent.

  The N-substituted maleimide synthesis reaction is performed by heating the reaction system to 100 to 150 ° C. for 1 to 15 hours. In the present invention, the synthesis reaction temperature of N-substituted maleimides is particularly preferably 100 to 140 ° C. When the synthesis reaction temperature is less than 100 ° C., there is a problem that the yield decreases. When the synthesis reaction temperature is 140 ° C. or more, polymerization of N-substituted maleimides synthesized by the side reaction proceeds and the synthesized N -Problems arise in that the purity and yield of substituted maleimides are reduced.

  Regarding the method of adding maleic anhydride and primary amine in the present invention, during the synthesis of N-substituted maleimide, the content of the primary amine in the reaction system should not exceed 1 molar ratio to maleic anhydride. There is no particular limitation.

  In the present invention, the N-substituted maleimide synthesis reaction can also be performed in the presence of a stabilizer. Examples of stabilizers include methoxybenzoquinone, hydroquinone, t-butylcatechol, t-butylhydroquinone, zinc dimethyldithiocarbamate, copper dibutyldithiocarbamate and the like.

  After completion of the reaction in the present invention, a reaction solution containing N-substituted maleimides obtained by separating the catalyst from the reaction system through filtration is distilled under reduced pressure at 50 to 150 ° C. under a pressure condition of 0.1 to 100 mmHg. By separating the solvent, high-purity N-substituted maleimides can be obtained.

  Further, the reaction solution containing the N-substituted maleimides can be washed with water and then distilled under reduced pressure to obtain high-purity N-substituted maleimides.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, the scope of the present invention is not limited to these Examples.

(Example 1)
In a 1 L reactor having a stirrer, a thermometer, a water separator and a cooler, 600 g of toluene as a solvent and 73 g of silica gel (trade name: Wakogel C-100, Wako pure chemical Industries, Ltd. production and sales) as a catalyst carrier After the addition, 42.5 g of 60% aqueous solution of 1-hydroxyethylidene-1,1-diphosphonic acid as a catalyst was continuously administered for 30 minutes, the temperature of the reaction system was raised to 115 ° C., and the water contained in the catalyst Was removed from the reaction system through azeotropic distillation. Thereafter, 150 g of aniline and 165.9 g of maleic anhydride melted at 80 ° C. were administered over 2 hours. During the reaction, water produced by the dehydration ring closure reaction was removed from the reaction system together with toluene through azeotropic distillation. The toluene removed from the reaction system was subjected to a synthesis reaction for another 5 hours while being re-administered inside the reaction system. After completion of the synthesis reaction, the supported catalyst was separated through filtration, and an N-phenylmaleimide toluene solution was recovered. The recovered N-phenylmaleimide toluene solution was heated to 80 ° C. under reduced pressure of 10 mmHg, and toluene was removed by distillation under reduced pressure to obtain 281.4 g of N-phenylmaleimide having a purity of 97.1% as yellow crystals. This was a 97.9 mol% yield based on the added aniline.

(Example 2)
The same procedure as in Example 1 was performed except that 159.8 g of cyclohexylamine was added instead of 150 g of aniline. As a result, 289.1 g of N-cyclohexylmaleimide having a purity of 95.7% was obtained, and the yield was 95.9 mol% based on the added cyclohexylamine.

Example 3
Example 1 except that 51.0 g of a 50% aqueous solution of amino-tri (methylene) phosphonic acid was used in place of 42.5 g of a 60% aqueous solution of 1-hydroxyethylidene-1,1-diphosphonic acid as a catalyst. It performed by the method. As a result, 278.7 g of N-phenylmaleimide having a purity of 95.5% was obtained, and the yield was 95.4 mol% based on the added aniline.

Example 4
N-phenylmaleimide was synthesized in the same manner as in Example 1, and an N-phenylmaleimide toluene solution was recovered. Add 900 g of distilled water to the recovered N-phenylmaleimide toluene solution, stir at 65 ° C. for 30 minutes, stop stirring for 30 minutes, separate the aqueous layer, and recover the N-phenylmaleimide toluene solution. A purification process was performed. The obtained N-phenylmaleimide toluene solution was heated to 80 ° C. under reduced pressure of 10 mmHg, and toluene was removed by distillation under reduced pressure to obtain 272.9 g of N-phenylmaleimide having a purity of 99.7% as yellow crystals. This was a 97.5 mol% yield based on the added aniline.

(Comparative Example 1)
To a 1 L reactor having a stirrer, a thermometer, a water separator and a condenser, 600 g of toluene as a solvent and 30.0 g of 85% orthophosphoric acid as a catalyst were continuously administered for 30 minutes, and the temperature of the reaction system was 115 ° C. And the water contained in the catalyst was removed from the reaction system through azeotropic distillation. Thereafter, 150 g of aniline and 165.9 g of maleic anhydride melted at 80 ° C. were administered over 2 hours. During the reaction, water produced by the dehydration ring closure reaction was removed from the reaction system together with toluene through azeotropic distillation. The toluene removed from the reaction system was subjected to a synthesis reaction for another 5 hours while being re-administered inside the reaction system. After completion of the synthesis reaction, the liquid orthophosphoric acid catalyst turned red was separated through layer separation, and an N-phenylmaleimide toluene solution was recovered. The recovered N-phenylmaleimide toluene solution was heated to 80 ° C. under reduced pressure of 10 mmHg, and toluene was removed by distillation under reduced pressure to obtain 264.8 g of N-phenylmaleimide having 91.0% purity of yellow crystals. This was a yield of 86.4 mol% based on the added aniline.

(Comparative Example 2)
To a 1 L reactor having a stirrer, a thermometer, a water separator and a condenser, 600 g of toluene as a solvent and 42.5 g of a 1-hydroxyethylidene-1,1-diphosphonic acid 60% aqueous solution as a catalyst were continuously administered for 30 minutes. The temperature of the reaction system was raised to 115 ° C., and water contained in the catalyst was removed from the reaction system through azeotropic distillation. Water was removed from the 60% aqueous solution of 1-hydroxyethylidene-1,1-diphosphonic acid added as a catalyst, and a phenomenon occurred in which the catalyst adhered to the reactor wall and the stirrer while changing to a solid state. Thereafter, 150 g of aniline and 165.9 g of maleic anhydride melted at 80 ° C. were administered over 2 hours. During the reaction, water produced by the dehydration ring closure reaction was removed from the reaction system together with toluene through azeotropic distillation. The toluene removed from the reaction system was subjected to a synthesis reaction for another 5 hours while being re-administered inside the reaction system. After completion of the synthesis reaction, a solid catalyst and an N-phenylmaleamic acid precipitate produced as a reaction intermediate were separated through filtration, and an N-phenylmaleimide toluene solution was recovered. The recovered N-phenylmaleimide toluene solution was heated to 80 ° C. under reduced pressure of 10 mmHg, and toluene was removed by distillation under reduced pressure to obtain 188.9 g of N-phenylmaleimide having a purity of 96.6% as yellow crystals. This was a 65.4 mol% yield based on the added aniline.

(Comparative Example 3)
The same procedure as in Example 1 was performed, except that 30.0 g of 85% aqueous solution of orthophosphoric acid was used instead of 42.5 g of 60% aqueous solution of 1-hydroxyethylidene-1,1-diphosphonic acid as a catalyst. As a result, 275.2 g of N-phenylmaleimide having a purity of 90.1% was obtained, and the yield was 88.9 mol% based on the added aniline.

  Table 1 below shows the amounts of organic solvents, catalysts, primary amines, maleic anhydride and the like used in the examples and comparative examples.

  Table 2 below shows the purity of the N-substituted maleimide in each Example and Comparative Example, and the yield relative to the added aniline. From Table 2, in the case of the comparative example, it is difficult to satisfy the high purity and the high yield of the N-substituted maleimide at the same time, but in the case of the example produced under the supported catalyst in which the organic phosphonic acid was supported on the solid support. It can be seen that high purity and high yield are satisfied at the same time.

  As described above, according to the present invention, the effect of providing a method for synthesizing and producing high-purity N-substituted maleimides in high yield by suppressing the occurrence of side reactions during the synthesis of N-substituted maleimides. There is.

  Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

Claims (11)

A method for producing N-substituted maleimides, comprising:
Organic solvent, an organic phosphonic acid in the presence of a supported catalyst supported on a solid carrier, is administered a first amine and maleic anhydride, characterized in that synthesizing N- substituted maleimides, further the organic A method for producing N-substituted maleimides, characterized in that phosphonic acid has a melting point of 150 ° C or higher and is insoluble in N-substituted maleimides. The organic phosphonic acid includes 2-phosphonobutane-1,2,4-tricarboxylic acid, 2-hydroxyphosphonoacetic acid, aminotrimethylenephosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, bishexamethylenetriaminepenta The method for producing N-substituted maleimides according to claim 1, wherein the method is selected from the group consisting of methylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, and diethylenetriaminepentamethylenephosphonic acid.   The method for producing N-substituted maleimides according to claim 1, wherein the solid support has a surface area of 100 m2 / g or more. The N- according to claim 1 or 3 , wherein the solid support is selected from the group consisting of diatomaceous earth, zirconium oxide, silica, silica-alumina, titanium dioxide, activated carbon, clay, and montmorillonite. A method for producing substituted maleimides.   The N-substituted maleimide according to claim 1, wherein the catalyst is used in a molar ratio of 0.1 to 1.0 with respect to the primary amines based on the phosphonic acid in the catalyst molecule. Manufacturing method.   The primary amines include methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, sec-butylamine, iso-butylamine, tert-butylamine, n-hexylamine, n-octylamine, n-decylamine, The method for producing N-substituted maleimides according to claim 1, wherein the method is selected from the group consisting of n-dodecylamine, cyclohexylamine, and aniline.   The method for producing N-substituted maleimides according to claim 1, wherein the maleic anhydride is used in a molar ratio of 1.0 to 1.1 with respect to the primary amines.   The method for producing N-substituted maleimides according to claim 1, wherein the organic solvent is a nonpolar solvent azeotropically distilled with water and has a boiling point of 80 to 160 ° C. The organic solvent is selected from the group consisting of benzene, toluene, xylene, ethylbenzene, isopropylbenzene, cumene, mesitylene, chlorobenzene, ethylcyclohexane, dichlorobenzene, dodecane, nonane, and trimethylhexane. A method for producing the N-substituted maleimide according to 1 or 8 . The method for producing N-substituted maleimides according to claim 1 or 8 , wherein the organic solvent is used in an amount of 2 to 10 times by weight based on the first amine.   The method for producing N-substituted maleimides according to claim 1, wherein the synthesis reaction temperature is 100 to 140 ° C.