JPH0312056B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is a N-based material useful as a heat resistance improver for resins such as ABS, MMA, and PVC, and as an intermediate raw material for pharmaceuticals and agricultural chemicals.
- An improved method for producing substituted maleimide compounds. [Prior Art] Conventionally, as a method for producing an N-substituted maleimide compound from maleic anhydride and a primary amine via a dicarboxylic acid monoamide compound, for the latter half of the dehydration reaction, (1) a dehydrating agent such as acetic anhydride is applied. method (e.g., Japanese Patent Publication No. 46-29140, USP2444536),
(2) A method of azeotropic dehydration of produced water with a solvent using an acid and/or a base as a catalyst (for example, Japanese Patent Publication No. 47-24024)
It has been known. However, the method (1) consumes an equimolar amount of dehydrating agent with respect to the produced water, which is economically disadvantageous. On the other hand, method (2) generally requires high temperatures and has insufficient yield and quality. Therefore, in order to increase the solubility of the catalyst and intermediate dicarboxylic acid monoamide compounds and to facilitate the reaction, part or all of the nonpolar solvent was replaced with N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone. A method of reacting in place of an aprotic polar solvent such as
46394, JP-A-60-100554, JP-A-60-112758)
However, since these solvents also have a high solubility for the target product, the N-substituted maleimide compound, in order to remove the N-substituted maleimide, the solvent must be removed by distillation or the solvent must be poured into a large amount of water. A complicated separation process such as addition and precipitation of crystals is required. Furthermore, these solvents are generally expensive and impose a heavy economic burden. [Problems to be Solved by the Invention] The inventors conducted studies to improve the above-mentioned drawbacks and find a more advantageous method regarding the method using a nonpolar solvent and an acid catalyst. As a result, they discovered that by adding an onium compound having a carbon number within a specific range to the reaction system, the reaction rate was significantly accelerated and side reactions were significantly reduced, leading to the completion of the present invention. That is, in the present invention, when producing an N-substituted maleimide by cyclodehydrating a dicarboxylic acid monoamide compound obtained from maleic anhydride and a primary amine in a nonpolar solvent in the presence of an acid catalyst,
This is a novel and improved method characterized by the addition of an onium compound with a specific structure.
An object of the present invention is to provide a method in which a -substituted maleimide can be obtained in high yield and separation from a solvent and a catalyst is extremely easy. [Means for Solving the Problems] As the primary amine applied in the present invention, a compound represented by the following general formula is recommended. RNH ₂ (wherein R is an alkyl group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group, a phenyl group, or a group substituted with an alkyl, halogen, alkoxy, carboxy, nitro or hydroxyl group) phenyl group or naphthyl group) Specifically, methylamine, ethylamine, n-
Butylamine, n-octylamine, 2-ethylhexylamine, n-dodecylamine, n-octadecylamine, cyclohexylamine, aniline, toluidine, xylidine, ethylaniline,
Isopropylaniline, dodecylaniline, p-
Examples include chloroaniline, 2,4-dichloroaniline, anisidine, phenetidine, aminobenzoic acid, nitroaniline, and aminophenol. The onium compound used in the present invention is represented by the following general formula (). [R ¹ R ² R ³ MR ⁴ ] ⁺ Y ^- () In the above general formula, the total number of carbon atoms contained in R ¹ , R ² , R ³ and R ⁴ is 10 to 80, preferably 12
~50. If this condition is met, the structure or combination of each substituent does not matter, and includes straight chain, branched chain, cyclic structure which may have a substituent, aromatic ring structure, or such ring or aromatic ring. Either a straight chain or a branched hydrocarbon group may be used. Furthermore,
Those with the following pyridine or piperidine structures can also be used.

【formula】

[Formula] Furthermore, those having the following betaine structure are also effective. R ¹ R ² R ³ M ⁺ CH ₂ COO ^- () In the general formula, R ¹ , R ² and R ³ represent a hydrocarbon group having a total of 10 to 80 carbon atoms. The same is true. When the total number of carbon atoms contained in substituents R ¹ , R ² , R ³ and R ⁴ in the general formula and substituents R ¹ , R ² and R ³ in the general formula is less than 10, an acid catalyst is added to the reaction system. Even when onium compounds have the ability to homogenize, no improvement effect on the reaction rate or yield is observed, and on the contrary, some onium compounds exhibit a negative effect on the reaction rate.
On the other hand, if the total number of carbon atoms is too large, separation of the onium compound becomes difficult and the purity of the target N-substituted maleimide compound decreases. Further, M ⁺ represents N ⁺ , P ⁺ , As ⁺ or Sb ⁺ . The anion Y ^- is a halogen ion such as Cl ^- , Br ^- , I ^- , an inorganic anion such as HSO ₄ ^- , ClO ₄ ^- , CN ^- , H ₂ PO ₄ ^- , OH ^- , CH ₃ SO ₃ ^- ,

Organic anions such as [Formula] can be used. Specifically, triethylhexylammonium bromide, trimethyldecylammonium bromide, trimethyldodecylammonium chloride,
trimethyltetradecylammonium bromide,
trimethyloctadecyl ammonium chloride,
Tetrabutylammonium bromide, triethyldecylammonium bromide, methyltriphenylammonium chloride, tetrahexylammonium chloride, triethylhexadecylammonium bromide, methyltridecylammonium chloride, methyltrinonylammonium chloride, dimethyldioctadecylammonium chloride, benzyltrimethylammonium chloride,
Benzyltriethylammonium bromide, triethylhexylammonium iodide, tetrabutylammonium bisulfate, benzyltriethylammonium hydroxide, methyltrioctylammonium perchlorate, butylpyridinium bromide, heptylpyridinium cyanide, dodecylpyridinium chloride, tetraphenylphosphonium bromide , tetraphenylarsonium chloride, tetraphenylstibonium bromide, dimethyldodecylaminoacetic acid betaine, dimethyloleylaminoacetic acid betaine, and the like. Next, acid catalysts include inorganic acids such as sulfuric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, sulfuric anhydride, metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, and polyphosphoric acid, methanesulfonic acid, p-toluenesulfonic acid, and benzene. Organic acids such as sulfonic acid and naphthalenesulfonic acid can be used. Solvents may be used alone or in mixtures, preferably within the boiling point range.
Any solvent may be used as long as it is non-polar and has a temperature of 90 to 150°C and can azeotropically distill off the produced water. For example, toluene,
xylene, ethylbenzene, cumene, hexane,
Hydrocarbons such as octane, decane, cyclohexane, methylcyclohexane, ethylcyclohexane, light oil, etc., and halogen-containing hydrocarbon compounds such as chlorobenzene, dichloroethane, trichloroethane, perchloroethane, etc. can be used alone or in a mixture of two or more of them. The reaction in the method of the present invention is to react maleic anhydride and the above-mentioned primary amine in a nonpolar solvent at a temperature of 150°C or less, preferably 20 to 80°C to produce a dicarboxylic acid monoamide, and then add the resulting reaction mixture to the Add catalyst and onium compound and heat to 90-150℃
It is generally carried out by stirring and heating, preferably at 100 to 140°C, and azeotropically dehydrating the water produced by the reaction. However, after the dehydration reaction of the dicarboxylic acid monoamide compound, maleic anhydride and a primary amine are reacted in a different solvent, such as acetone, and the intermediate dicarboxylic acid monoamide compound is once separated,
The reaction can also be carried out in a non-polar solvent in the presence of an acid catalyst and an onium compound. Here, the amount of maleic anhydride and primary amine used is 1.0 to 1.0 to 1 mol of maleic anhydride per mol of primary amine
1.5 mol is preferred. Further, it is preferable to use the nonpolar solvent in an amount of 2 to 15 times (by weight) the amount of the primary amine. The onium compound is 0.1 to 15% by weight based on the primary amine,
Particularly preferred is 1.0 to 10% by weight. If the amount of the onium compound added is too small, the reaction rate will be slow, and both the purity and yield of the target N-substituted maleimide compound will be low. On the other hand, if more than 15% is added, it will only be economically disadvantageous and no advantage will be recognized. Next, the acid catalyst is suitably used in an amount of 0.5 to 20% by weight based on the primary amine, although it depends on the type. When the reaction is carried out under the above conditions, if the reaction mixture is cooled, the target N-substituted maleimide will precipitate as crystals, which should be filtered or centrifuged and then treated with water and/or alkaline water. After washing and drying, the desired product can be obtained. Also, once after the reaction
It is also possible to cool the reaction solution to about 70°C, wash it with water and/or alkaline water, and then cool it to room temperature to separate and dry the precipitated N-substituted maleimide crystals. Furthermore, if a high degree of purification is desired, recrystallization can be performed using a solvent such as isopropyl alcohol. The reaction solution that remains after removing the N-substituted maleimide that has precipitated as crystals can be used as is, or the remaining acid catalyst can be neutralized with an alkali, and in some cases, the formed salt can be washed away with water before being used in the next reaction. Can be used repeatedly. [Example] The present invention will be explained in detail with reference to Examples below. Example 1 47.5 g (0.50 mol) of maleic anhydride, 130 g of xylene, and 88 g of toluene were charged into a four-necked flask equipped with a cooling tube with a water separator, a thermometer, and a stirrer, and the mixture was stirred at a reaction temperature of 40°C. Aniline 44.7g
(0.48 mol) was added dropwise little by little over 1 hour, and the reaction was continued for an additional 30 minutes at the same temperature. To the resulting reaction mixture were added 2.5 g of sulfuric acid and 0.9 g of benzyltrimethylammonium chloride, and the mixture was heated to reflux temperature (125
~130℃) and remove the produced water for about 30 minutes.
Allowed time to react. After the reaction was completed, the mixture was cooled to room temperature, and pale yellow needle-shaped N-phenylmaleimide was precipitated. This was filtered, washed with 10% sodium carbonate water and water, dried, and
-47 g of phenylmaleimide were obtained. This melting point is 88
Purity was 97.5% by GPC analysis at ~90°C.
Further, as a result of analysis of N-phenylmaleimide remaining in the reaction solution, 30 g was found to be 93% yield based on the aniline used when combined with the N-phenylmaleimide obtained as crystals. Next, using the remaining reaction solution, maleic anhydride and aniline were reacted in the same manner as the first reaction, and the reaction solution was repeatedly used. As a result, 78 g of N-phenylmaleimide was obtained by filtering, washing and drying. Yield is based on aniline
The purity was 94% and the purity was 97.5%. When the reaction solution is reused, the amount of N-phenylmaleimide obtained as crystals increases because the amount dissolved in the reaction solution is negligible. Example 2 In a four-necked flask similar to Example 1, 47.5 g of maleic anhydride was dissolved in 88 g of toluene and 130 g of xylene, and 44.7 g of aniline was added dropwise thereto over 1 hour while stirring at 30°C. The mixture was further heated and stirred at the same temperature for 30 minutes to obtain N-phenylmaleamic acid.
9.5 g of p-toluenesulfonic acid monohydrate and 0.8 g of trimethyltetradecylammonium bromide were added to the resulting reaction mixture, and the mixture was heated to reflux temperature (125-130
Heat and stir at a temperature of approximately 2.5 °C) while removing generated water.
Allowed time to react. After the reaction is completed, cool to approximately 70℃,
After washing with a 10% aqueous sodium bicarbonate solution and warm water, the crystals were cooled to room temperature and the resulting crystals were filtered and dried to obtain 50 g of N-phenylemaleimide. This melting point is
As a result of GPC analysis at 88-90°C, the purity was 98.0%. Further, 26 g of N-phenylmaleimide remained in the reaction solution, and when combined with that obtained as crystals, the yield was 92% based on the aniline used. Next, using the remaining reaction solution, maleic anhydride and aniline were reacted in the same manner as in the first reaction, and the reaction solution was used repeatedly. As a result, the crystals were filtered and dried.
77 g of phenylmaleimide was obtained. The yield was 93% based on the aniline used, and the purity was 98%. Example 3 Table 1 shows the yield and purity when the reaction solution was repeatedly used, except that only the type of onium compound and the amount added were changed, and the other conditions were the same as in Example 2. Example 4 Example 2 except that 0.48 mol of various primary amines shown in Table 2 was used instead of aniline in Example 2.
Table 2 shows the results of the same reaction. yield,
Purity is the result when the reaction solution is reused. Comparative Example 1 In Example 1, the reaction was carried out under the same conditions as in Example 1 except that benzyltrimethylammonium chloride was not added. In this case, even after 3 hours of reaction, insoluble crystals remained, which were filtered and washed with water at a temperature of 80 DEG C. to obtain 36.7 g of N-phenylmaleamic acid as a reaction intermediate. The mixture was further cooled to room temperature, and N-phenylmaleimide precipitated was separated by filtration, washed with 10% sodium carbonate water and water, and dried to obtain 19 g of N-phenylmaleimide. Its melting point is 84-87℃, GPC
The analysis results showed a purity of 93.5%. Next, using the remaining reaction solution, the reaction solution was repeatedly reacted with maleic anhydride in the same manner as in the first reaction. As a result, 43 g of N-phenylmaleimide was obtained by filtering, washing, and drying. The yield was 53% based on aniline, and the purity was 93%. Comparative Example 2 Using an onium compound having a predetermined number of carbon atoms or less in place of benzyltrimethylammonium chloride,
Table 3 shows the results of the reaction according to Example 1. The yield and purity are the results when the reaction solution was reused. [Effects of the Invention] According to the method of the present invention, the reaction rate increases, a sufficient reaction rate can be obtained even when using a common and inexpensive non-polar solvent, and there are few side reactions, so high purity N can be obtained.
-Substituted maleimides are obtained in high yields. Furthermore, since the present invention does not use a polar solvent, the desired N-substituted maleimide compound precipitates as crystals simply by cooling after the reaction, and can be easily separated.

【table】

【table】

【table】

【table】

【table】

[Claims]

1. A method for transporting and storing maleimides, which comprises handling maleimides in the form of an acrylonitrile solution in the presence of a polymerization inhibitor.