JP2017066132A - Process for producing maleimide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for imidization at low temperature without using a strongly acidic dehydration catalyst, in producing maleimide from maleamic acid using an acid catalyst.SOLUTION: In a process for producing maleimide, when imidizing a maleamic acid obtained by reacting a primary amine and a maleic anhydride, in a solvent using a dehydration catalyst, an aliphatic carboxylic acid and/or aliphatic anhydride is used as the dehydration catalyst. The use amount of the aliphatic carboxylic acid and/or aliphatic anhydride is 0.1 equivalent or more in total of the aliphatic carboxylic acid and aliphatic anhydride with respect to the primary amine.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing maleimide.

Maleimide is useful as a raw material for various resins, agricultural chemicals, pharmaceuticals, and the like, and is particularly useful as a heat resistance improver for resins such as ABS, PMMA, and PVC.

A general method for producing maleimide is a method in which maleic anhydrides and primary amines are reacted in a solvent to form maleamic acid, which is dehydrated and cyclized in the presence of an acid catalyst as a dehydration catalyst to imidize. It is. For example, Patent Document 1 discloses a method in which maleamic acid is dehydrated with an acid catalyst that is a dehydration catalyst, and the resulting water is azeotropically removed and cyclized in the molecule to imidize. As the acid catalyst, strong inorganic acids such as sulfuric acid and phosphoric acid, or strong organic acids such as paratoluenesulfonic acid and methanesulfonic acid are used. Patent Document 2 discloses a method in which maleamic acid is imidized by dehydration ring closure in the presence of a dehydration catalyst using a solvent obtained by mixing an aprotic polar solvent and an azeotropic solvent such as toluene. Yes. In these methods, water generated by imidization is azeotroped with a solvent such as toluene to condense vapor, and the solvent and water are separated, and only the solvent is returned to the reaction system under reflux. Is adopted.

In this method, it has been pointed out that various by-products generated during the reaction block the condenser for condensing the vapor and reduce the function of the water separator (Patent Documents 3 to 5). ). Moreover, in the above-described conventional method, since a strong acid is used as a catalyst, there is a problem that an expensive corrosion-resistant material must be used for the reactor and peripheral devices. Furthermore, when a strong acid is used as a catalyst, a polymerization reaction of the vinyl group of the resulting maleimide occurs, so that oligomers of maleimide dimers and trimers are easily produced as by-products, and it is difficult to obtain high-purity maleimide. There was a problem. In order to avoid such a problem, Patent Document 6 discloses a method of imidizing maleamic acid without using a strong acid using a zinc compound as a catalyst. Patent Document 7 discloses a method using a salt of a strong acid and triethylamine as a dehydration catalyst. However, even in these methods, it is essential to remove the generated water using azeotropy, and the problems associated with azeotropy as described above have not been solved. Patent Document 8 discloses a method for producing maleimide at a low temperature using a dehydrating agent such as dicyclocarbodiimide (DCC) or acetic anhydride and a basic compound such as triethylamine or sodium acetate. When such a basic compound is used, it is difficult to produce maleimide in high yield because the conversion rate from maleic acid, which is a reaction raw material, to maleimide is low and various side reactions occur. It was.

Japanese Patent Publication No. 51-40078 Japanese Patent Publication No.55-46394 Japanese Patent Publication No. 7-74200 Japanese Patent No. 4014683 JP 2003-3000956 A Japanese Patent No. 2899027 U.S. Pat. No. 5,973,166 US Patent H424

The present invention solves the above-described problems, and an object thereof is to provide an efficient and economical method for producing maleimide.

In the production of maleimide, it was found that when a specific reaction aid was used, the reaction proceeded efficiently below the boiling point of the reaction solvent, and the above problems were solved all at once, and the present invention was completed.

The present invention has the following objects.
<1> An aliphatic carboxylic acid and / or an aliphatic acid anhydride as a dehydration catalyst when imidating a maleamic acid obtained by reacting a primary amine with maleic anhydride in a solvent using a dehydration catalyst And the amount used is 0.1 equivalent or more in total of the aliphatic carboxylic acid and the aliphatic acid anhydride with respect to the primary amine.
<2> A method for producing maleimide, characterized in that imidization is performed without azeotropic removal of water produced by imidization at a temperature not higher than the boiling point of the solvent.

Since the maleimide production method of the present invention does not use a strong acid such as an inorganic acid as a dehydration catalyst, it is not necessary to use an expensive corrosion-resistant material for the reaction apparatus. In addition, since the water produced by the reaction can be reacted at a low temperature without azeotropic removal, problems such as clogging of the capacitor do not occur. Furthermore, since the by-products such as oligomers are reduced in the produced maleimide, it is copolymerized with other copolymerizable vinyl compounds such as vinyl ethers, and random copolymers and alternating copolymers with excellent uniformity are obtained. A polymer can be obtained.

2 is an NMR chart (part) of the maleimide solution obtained in Example 1. FIG.

Hereinafter, the present invention will be described in detail.
Maleimide is a compound having a chemical structure in which a primary monoamine component or primary diamine component (hereinafter sometimes abbreviated as “primary amine”) and a maleic acid component are dehydrated and condensed. Here, as the primary amine, aliphatic monoamine, alicyclic monoamine, aromatic monoamine, aliphatic diamine, alicyclic diamine, aromatic diamine can be used, and specific examples include methylamine, ethylamine, propyl Aliphatic monoamines such as amine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine and dibutylamine, alicyclic monoamines such as cyclohexylamine and dicyclohexylamine, aniline, toluidine, diphenylamine, Aromatic monoamines such as naphthylamine, 1,2-ethanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, , 8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, 1, 15-pentadecanediamine, 1,16-hexadecanediamine, 1,17-heptadecanediamine, 1,18-octadecanediamine, 2- / 3-methyl-1,5-pentanediamine, 2-methyl-1,8-octane Aliphatic diamines such as diamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methyl-1,9-nonanediamine and dimerdiamine, 1,3- / 1,4-cyclohexanediamine, 1,3- / 1,4-cyclohexanedimethylamine, bis (4-aminocyclohexyl) methane, (4-aminocyclohexyl) propane, bis (3-methyl-4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) propane, 5-amino-2,2,4-trimethyl-1-cyclo Alicyclic rings such as pentanemethylamine, 5-amino-1,3,3-trimethylcyclohexanemethylamine (isophoronediamine), bis (aminopropyl) piperazine, bis (aminoethyl) piperazine, norbornanedimethylamine, tricyclodecanedimethylamine Formula diamine, 4,4'-diaminodiphenyl ether, m-phenylenediamine, p-phenylenediamine, 4,4'-diphenylmethanediamine, 4,4'-diphenyletherdiamine, diphenylsulfone-4,4'-diamine, diphenyl-4 4'-di Aromatic diamines such as amine, o-tolidine, 2,4-tolylenediamine, 2,6-tolylenediamine, xylylenediamine, and naphthalenediamine are exemplified. These are used alone or in combination of two or more. Among these primary amines, alicyclic diamines such as 1,4-cyclohexanediamine, and aliphatic diamines such as 1,10-decanediamine, 1,12-dodecanediamine, and dimerdiamine are preferably used. As the dimerdiamine, commercially available products such as Cognis Japan, trade name “Versamine 551”, Croda, trade name “Puriamine 1074”, “Puriamine 1075” and the like are used.

In the maleimide production method of the present invention, first, a primary amine and maleic anhydride are reacted in a solvent to obtain a maleamic acid, and then the amic acid portion of the maleamic acid is imidized to obtain a maleimide solution. Maleic anhydride as a reaction substrate is used in an approximately equivalent amount (0.95 to 1.05 equivalent) with respect to the primary amine. The imidization is preferably performed at a temperature not higher than the boiling point (reflux temperature) of the solvent used without azeotropic removal of water generated by imidization. By doing in this way, use of the water separator with a possibility of blockage etc. is avoided. The reaction temperature during imidation is preferably 150 ° C. or lower, more preferably 130 ° C. or lower. The reaction time during imidation is preferably 2 hours or longer and 12 hours or shorter, more preferably 4 hours or longer and 10 hours or shorter. If the reaction time exceeds 12 hours, side reactions such as the formation of a vinyl polymer may easily occur. In less than 2 hours, the imidization reaction does not proceed sufficiently, and the conversion rate from maleamic acid to maleimide (hereinafter sometimes simply referred to as “conversion rate”) may decrease. Here, the conversion rate (%) can be confirmed by measuring proton NMR of the maleimide solution after completion of imidation (hereinafter sometimes simply referred to as “NMR”). Specifically, NMR was measured under the following conditions, and the integrated value (A) of the peak corresponding to the proton of the methylene group directly bonded to the nitrogen atom of maleimide and the peak corresponding to the proton of the methylene group directly bonded to the nitrogen atom of maleamic acid The conversion rate can be confirmed by calculating A / (A + B) * 100 using the integral value (B). In the maleimide production method of the present invention, a maleimide solution having a conversion rate of 50% or more can be obtained.

<NMR measurement conditions>
Apparatus: Nuclear magnetic resonance apparatus (manufactured by JEOL Ltd., model number: ECA500)
Frequency: 500.16MHz
Reference material: Tetramethylsilane Measurement temperature: 25 ° C
Solvent: deuterated chloroform

The imidization reaction is performed in the presence of an aliphatic carboxylic acid and / or an aliphatic acid anhydride. Here, the aliphatic carboxylic acid and the aliphatic acid anhydride as the dehydration catalyst can be treated as chemical equivalents. That is, the aliphatic carboxylic acid is converted into an aliphatic acid anhydride by a dehydration reaction during the maleimidation reaction, and the aliphatic acid anhydride is converted into an aliphatic carboxylic acid by a hydrolysis reaction. As these aliphatic carboxylic acids, acetic acid, propionic acid, maleic acid, succinic acid, malic acid, fumaric acid and the like are used. As the aliphatic acid anhydride, acid anhydrides such as acetic acid, propionic acid, maleic acid, succinic acid and malic acid are used. Among these, maleic acid, malic acid, acetic acid and acid anhydrides thereof are preferably used. The use amount of the aliphatic carboxylic acid and / or the aliphatic acid anhydride is 0.1 equivalent or more in total of the aliphatic carboxylic acid and the aliphatic acid anhydride with respect to the primary amine as the raw material. It is preferable to make it equal to or greater than the equivalent. If it is less than 0.1 equivalent, the imidation reaction may not proceed sufficiently. Moreover, it is preferable that the usage-amount of a dehydration catalyst shall be 6.0 equivalent or less in total with aliphatic carboxylic acid and an aliphatic acid anhydride with respect to a primary amine. If it exceeds 6.0 equivalents, side reactions may easily occur.
As described above, by using an aliphatic carboxylic acid and / or an aliphatic acid anhydride as a dehydration catalyst, the imidization reaction is allowed to proceed efficiently without azeotropic separation of water generated by the imidization reaction. be able to. In addition, imidation reaction can also be advanced by carrying out azeotropic separation of the water produced | generated by imidation reaction.

The solvent used in the reaction is not limited as long as it dissolves the product maleimide, but amide solvents such as N-methylpyrrolidone (NMP) and dimethylacetamide (DMAc), toluene, xylene and the like. Hydrocarbon solvents, ether solvents such as glyme and diglyme are preferably used. These solvents are used alone or in combination of two or more. Among these, a mixed solvent composed of an amide solvent and a hydrocarbon solvent is preferably used. In addition, it is preferable that the reflux temperature of these solvents shall be 130 degrees C or less.

As solid content concentration in the case of reaction, it is preferable to set it as 20-70 mass%, and it is more preferable to set it as 30-70 mass%. In addition, solid content concentration is the mass% with respect to the charge solution mass (total mass of a reaction substrate, a solvent, and a dehydration catalyst) of reaction substrate (primary amine and maleic anhydride) total mass.

From the maleimide solution obtained by the method of the present invention, maleimide can be purified and isolated as a solid powder by a known method (for example, reprecipitation by adding a poor solvent such as water or alcohol).

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the examples.

<Example 1>
In a glass reaction vessel, under a nitrogen atmosphere, Dimerdiamine (“Puriamine 1075” manufactured by Croda Japan Co., Ltd., molecular weight: 549): 1.0 mol, a mixed solvent composed of toluene and DMAc (mass ratio: toluene / DMAc = 80 / 20) was added and stirred. Next, 2.10 mol of maleic anhydride (1.05 equivalent to dimerdiamine) was added to this solution, followed by stirring at 25 ° C. for 1 hour to obtain a maleamic acid solution. Thereafter, 2.0 mol of maleic acid (1.0 equivalent to dimerdiamine) and 2.0 mol of maleic anhydride (1.0 equivalent to dimerdiamine) were added to this solution, and the temperature was raised while stirring. The solution was heated to reflux (about 115 ° C.). The water produced by the reaction was refluxed for 3 hours without azeotropic separation, and then cooled to obtain an orange-yellow solution. The solid content concentration in this reaction was 30% by mass. The result of having measured NMR of this solution on the said conditions is shown in FIG. The integrated value (A) of the peak (δ: 3.5 PPM multiple line) corresponding to the proton of the methylene group directly bonded to the nitrogen atom of maleimide recognized in this NMR chart and the methylene group directly bonded to the nitrogen atom of maleamic acid When the conversion rate was calculated from the integral value (B) of the peak corresponding to protons (δ: 3.3PPM multiple line), the conversion rate was 61%. In FIG. 1, a plurality of peaks around 3 ppm are peaks derived from the methyl proton of DMAc used as a solvent.

<Example 2>
The reaction was carried out in the same manner as in Example 1 except that the reaction time for imidization was 6 hours. As a result, the conversion rate was 95%.

<Example 3>
In a nitrogen reaction atmosphere, dimerdiamine (“Puriamine 1075”, molecular weight: 549): 1.0 mol, mixed solvent consisting of toluene and NMP (mass ratio: toluene / NMP = 80) in a glass reaction vessel. / 20) was added and stirred. Next, 2.10 mol of maleic anhydride was added to this solution and then stirred at 25 ° C. for 1 hour to obtain a maleamic acid solution. Thereafter, 1.8 mol of maleic acid and 1.8 mol of maleic anhydride were added to this solution, and the temperature of the solution was raised to 95 ° C. with stirring, and heating was continued for 8 hours while maintaining the same temperature. Cooled to give an orange-yellow solution. The solid content concentration in this reaction was 30% by mass. When NMR of this solution was measured on the said conditions and the conversion rate was computed, the conversion rate was 92%.

<Example 4>
The reaction was carried out in the same manner as in Example 3 except that 1.8 mol of maleic acid and 1.8 mol of acetic anhydride were used as the dehydration catalyst. As a result, the conversion was 87%.

<Example 5>
The reaction was carried out in the same manner as in Example 3 except that 1.8 mol of malic acid and 1.8 mol of maleic anhydride were used as the dehydration catalyst. As a result, the conversion rate was 85%.

<Example 6>
As a result of carrying out the reaction in the same manner as in Example 3 except that 1,10-decanediamine was used as the diamine, the conversion rate was 94%.

<Example 7>
As a result of conducting the reaction in the same manner as in Example 3 except that 1,12-dodecanediamine was used as the diamine, the conversion rate was 95%.

<Example 8>
As a result of carrying out the reaction in the same manner as in Example 3 except that 1,4-cyclohexanediamine was used as the diamine, the conversion rate was 92%.

<Example 9>
As a result of carrying out the reaction in the same manner as in Example 3 except that only 1.8 mol of maleic acid was used as the dehydration catalyst, the conversion rate was 58%.

<Example 10>
As a result of carrying out the reaction in the same manner as in Example 3 except that only 1.8 mol of maleic anhydride was used as the dehydration catalyst, the conversion rate was 55%.

<Example 11>
As a result of performing the reaction in the same manner as in Example 3 except that 0.5 mol of maleic anhydride and 0.5 mol of maleic acid were used as the dehydration catalyst and the solid concentration was 40% by mass. Was 85%.

<Example 12>
As a result of performing the reaction in the same manner as in Example 3 except that 0.5 mol of maleic anhydride and 0.3 mol of maleic acid were used as the dehydration catalyst and the solid content concentration was 40% by mass, the conversion rate was as follows. Was 75%.

<Comparative Example 1>
As a result of carrying out the reaction in the same manner as in Example 3 except that the dehydration catalyst was 0.1 mol of maleic acid (0.05 equivalent to dimerdiamine), the conversion rate was less than 30%.

<Comparative example 2>
As a result of carrying out the reaction in the same manner as in Example 3 except that the dehydration catalyst was 0.1 mol of acetic acid (0.05 equivalent to dimerdiamine), the conversion rate was less than 30%.

<Comparative Example 3>
As a result of carrying out the reaction in the same manner as in Example 3 except that the dehydration catalyst was 0.1 mol of acetic anhydride (0.05 equivalent with respect to dimerdiamine), the conversion rate was less than 30%.

<Comparative example 4>
As a result of carrying out the reaction in the same manner as in Example 3 except that the dehydration catalyst was 0.1 mol of maleic anhydride (0.05 equivalent to dimerdiamine), the conversion rate was less than 30%. .

From the above results, it is clear that according to the production method of the present invention, a maleimide solution can be obtained at a high conversion without azeotropic removal of water generated by imidization.

The maleimide production method of the present invention can be reacted at a low temperature without using an expensive corrosion-resistant material in the reaction apparatus. In addition, since by-products such as oligomers are reduced, copolymerization with other copolymerizable vinyl compounds such as vinyl ethers to obtain random and alternating copolymers with excellent uniformity. Can do.

Claims (2)

When imidating a maleamic acid obtained by reacting a primary amine and maleic anhydride with a dehydration catalyst in a solvent, an aliphatic carboxylic acid and / or an aliphatic acid anhydride is used as the dehydration catalyst. And the usage-amount is 0.1 equivalent or more with the sum total of aliphatic carboxylic acid and an aliphatic acid anhydride with respect to a primary amine, The manufacturing method of the maleimide characterized by the above-mentioned. 2. The method for producing maleimide according to claim 1, wherein imidization is performed without azeotropic removal of water generated by imidization at a temperature not higher than the boiling point of the solvent.