JPS62138467A - Production of n-substituted maleimide - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high purity and in high yield, by dehydrating a dicarboxylic acid monoamide obtained from maleic anhydride and a primary amine, in the presence of an acid catalyst and a specific onium compound in a nonpolar solvent and separating and recovering a catalytic liquid phase. CONSTITUTION:A dicarboxylic acid monoamide obtained from maleic anhydride and a primary amine is reacted in the presence of an acid catalyst and one or more compounds selected from compounds shown by formula I-formula IV [R<1>-R<7> are hydrocarbon groups having 10-80 total carbon atoms (formula I and formula II) or 7-60 total carbon atoms (formula III and formula IV) in each compound; Y is Cl, Br HSO4, ClO4, CN, H2PO4, CH3SO3, group shown by formula V or OH; M is N, P, As or Sb] in a nonpolar solvent, a catalytic liquid phase is separated and recovered to give the titled compound useful as an improver for heat resistance of ABS resin, etc. The titled compound is obtained by the use of the inexpensive nonpolar solvent at high reaction rate in high purity and in high yield, the catalyst is readily recovered and the recovered catalyst and solvent can be directly reused advantageously.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention provides an N-substituted maleimide 1 which is useful as a heat resistance improver for resins such as ABS, MMA, and PVC, as well as as an intermediate in pharmaceuticals and pharmaceuticals. An improved method of manufacturing .

[Prior Art] Conventionally, as a method for producing N-directly converted maleimide 1~ from maleic anhydride and a primary amine via dicarboxylic acid monoamine 1~, the latter half of the Eisui reaction (in this case, (I ) A method of avoiding the action of a hydrating agent such as M acid anhydride (for example, Japanese Patent Publication No. 46-29140.USP 2.4/14.536), (
2) A method of using a salt M8 catalyst and avoiding the azeotrope of the produced water with the solvent (I9 Sue (: [, Japanese Patent Publication No. 47-2402
4) etc. are known. However, method (I) consumes an equimolar amount of dehydrating agent 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 compound and to facilitate the reaction, part or all of the non-chronic solvent was replaced with N,N-dimethylformamide, N
A method of reacting in place of an aprotic highly polar solvent such as
4, JP-A-60-112758>, these solvents also have a high solubility of the target product, N-substituted maleimide, so in order to extract the N-substituted maleimide, the solvent must be removed by vapor deposition. Otherwise, a complicated separation process is required, such as adding it to a large amount of water to precipitate crystals. Furthermore, these solvents are generally expensive and impose a heavy economic burden.

Furthermore, in such a method, it is difficult to recover and reuse the catalyst. That is, when a base such as a tertiary amine is used as a catalyst, the catalyst is dissolved in the reaction solution, and its recovery requires distillation or the like. On the other hand, when an acid such as sulfuric acid is used as a catalyst, an insoluble solid or a highly viscous liquid containing the catalyst is produced when the main solvent is in a small amount, and filtration at high temperatures is required to recover it. On the other hand, if a large amount of polar solvent is used, the catalyst will dissolve in the reaction solution, making it difficult to separate and recover it, and a large amount of acid catalyst will adhere to the precipitated crystals, which is unfavorable in terms of quality.

[Problems to be Solved by the Invention] The inventors previously discovered that in a method using a non-polar solvent and an acid catalyst, the reaction was accelerated by adding a specific onium compound, and the inventors discovered that the reaction was accelerated by adding a specific onium compound. We have just proposed a method for producing useful N-substituted maleimides (patent application 1983).
0-213154>.

In subsequent studies, it was found that this system separates the catalyst liquid phase after the reaction, and that the catalyst can be easily recovered and reused after the reaction, and that high-purity N-substituted maleimide can be obtained. Based on this finding, we have completed the present invention.

That is, the present invention provides an onium compound having a specific structure, 3, when producing an N-substituted maleimide by dehydrating and cyclodehydrating a dicarboxylic acid monoamide derived from maleic anhydride and a primary amine in the presence of an acid catalyst. Grade amine or ゛? This is a new and improved method characterized by adding one or more selected from amine oxides, reacting in a non-chronic solvent, and then separating and recovering the catalyst liquid phase.
An object of the present invention is to provide a method by which a -substituted maleimide can be obtained in high yield.

[Means for Solving the Problems] It is recommended that the primary amine used in the present invention be a compound represented by the following general formula.

NH2 (wherein R is an alkyl group, a halogen atom, an alkoxy group, a carboxyl group, an alkyl group having 1 to 20 carbon atoms, which may have a substituent such as a hydroxyl group, or a cycloalkyl group) ,) represents an engineering group or a naphthyl group) Specifically, methylamine, ethylamine, n-butylamine, n-ocdylamine, 2-ethylhexylamine, n-dodecylamine, n-octadecylamine, cyclohexylamine, aniline, toluidine , xylidine, ethylaniline, isopropylaniline, dodecylaniline, p-chloroaniline, 2,4-dichloroaniline, anisidine, phenetidine, aminobenzoic acid, →
Examples include troaniline and aminophenol.

The onium compound used in the present invention has the following general formula (
I>.

123 4+ [RRRMR] Y-(I> In the above general formula, the total number of carbon atoms contained in R, R2, R3 and I (:1 is necessarily 10 to 80, preferably 12
-! It's -50.

Furthermore, pyridine and piperidine below)? You can also use the No. 11 model.

In addition, the following betaine (?1'5 structure) is also effective.

123 + RRRM C+-12COO-(II) General formula (II
>, R, R and R3 have a total number of carbon atoms of 1
It represents a hydrocarbon group of 0 to 80, and the details are the same as those of the general formula (, [).

Also, M represents N, P, AS, or 3b.

As the anion Y-, a halogen ion such as C7-, Br-1I-, H3O-1 (J'O'-1CN'', anion) can be used.

Specifically, trimethyldecyl ammonium bromide,
Trimethyldecylammonium bromide, 1-limethyldodecylammonium chloride, trimethyltetradecylammonium bromide, 1-helimethyloctadecyl ammonium chloride, tetrabutylammonium bromide, 1-ethyldecylammonium bromide, methyltriphenylammonium chloride, tetrahexyl Ammonium chloride, triethylhexadecylammonium bromide, methyl 1-lysodylammonium chloride, methyltrinonylammonium chloride 1-, dimethylcyA-tadecylammonium chloride, benzyltri'methylammonium chloride, henzyltriedylammonium bromide, 1 ~Ethylhexylammonium iodine 1~, butylammonium bisulfate, pencil triethylammonium hydroxide, methyltrioctylammonium perchlorate,
Butylpyridinium bromide, heptylpyridinium cyanide, dodecylpyridinium chloride, TeI~raphenylphosphonium bromide, tetraphenylarsonium chloride, Tei~raphenylsudiobonium bromide,
and dimethyldodecylaminoacetic acid betaine, dimethyloleylamineacetic acid betaine, and the like.

Further, the tertiary amine used in the present invention is represented by the following general formula (III).

R" R6R7N (I[I) In the above general formula, the total number of carbon atoms contained in R, R6, and R7 is 7 to 60, preferably 8 to 40. Furthermore,
Those having the following pyridine or piperidine structures can also be used.

Substituent R5 in the above one-stage formula has 3 to 40 carbon atoms,
It preferably shows a hydrocarbon residue of 4 to 30.

Specifically, diethylbutylamine, diethylbutylamine, diethylhexylamine, dimethyloctylamine, dimethyldodecylamine, dimethyloctadecylamine, didodecylmethylamine, dioctadecylmethylamine, dimethylcyclohexylamine, N,N-dimethylaniline, N, Examples include N-diethylaniline, N,N-dimethyl-p-toluidine, 4-edylpyridine, 4-dodecylpyridine, N-dodecylpiperidine, and N-cedylpiperidine.

Further, the amine oxide used in the present invention is represented by the following general formula (Iv).

R5R6R7N-0 (IV) R5, R6, and R7 in the above general formula are represented by the general formula (III
).

Moreover, those having the following structure can also be used.

Substituent R5 in the above general formula has 3 to 40 carbon atoms,
It preferably shows a hydrocarbon residue of 4 to 30.

Specifically, diethylhexylamine oxy], diethylbutylamine oxyto, diethylhexylamine oxyto, dimethylocdylamine Δoxide, dimethyldodecylamine oxyto, dimethyloctadecylamine oxyto, di]~decylmethylamine oxide, Dioctadecylmethylamine oxide, dimethylcyclohexylamine oxide, N-dodecylpiperidine oxide, N
-Cedylbiperidine oxide, N,N-dimedylaniline oxide, N,N-diethylaniline oxide, 4-
Examples include ethylpyridine oxide.

In general formulas (I) to ff1(IV), as long as each condition::)7 is met, 11+¥ structure or coarse combination of substituents is not a problem, and linear or branched substituents are It may be a cyclic or aromatic ring, or a straight or branched hydrocarbon containing the ring or an aromatic ring. If the total number of carbon atoms is smaller than the specific range shown in each formula, the viscosity of the catalyst layer released after the reaction will become high and recovery will be difficult, while if it exceeds the range, the target N-
The amount of substituted maleimide dissolved in the catalyst layer increases, leading to a decrease in yield.

Acid catalysts include inorganic acids such as sulfuric acid, phosphoric acid, sulfurous acid, hypophosphorous acid, sulfuric anhydride, metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, methanesulfonic acid, p-toluenesulfonic acid, and benzenesulfonic acid. Acids, i]halic acids such as naphthalenesulfonic acid can be used.

The solvent preferably has a boiling point range of 90 to 150°C.
Any non-polar solvent that can azeotropically deposit the produced water may be used. For example, hydrocarbons such as 1 to toluene, xylene, ethylbenzene, cumene, hexane, octane, decane, cyclobenzene, methylcyclohexane, ethylcyclohexane, light oil, halogen-containing carbons such as chlorohensen, dichloroethane, trichloroethane, perchlorethylene, etc. A single hydrogen compound or a mixture of two or more of them can be used.

If the catalyst tends to dissolve in the system after the reaction, a solvent containing at least 5% by volume of a non-aromatic solvent may be used.

For example, this applies to the case where phosphoric acid is used at 6 fflff1%, pencil 1 to 2% by weight is used for aniline, and xylene or toluene is used alone as a solvent. 1. Separate the catalyst layer using raw solvent.

In the present invention, it is also possible to add an aprotic solvent such as N,N-dimethylformamide, N-methylpyrrolidone, etc., but no particular effect is expected. × The reaction in the method of the present invention is generally performed by reacting maleic anhydride with the above-mentioned primary amine in a non-polar solvent at a temperature of 150'C or less, preferably 20-80'C to produce a dicarboxylic acid monoamide. Then, an acid catalyst and an onium compound or a tri-treated amine or amine oxide (the above general formulas (I) to (IV), hereinafter referred to as "onium compound, etc.") were added to the 1q reaction mixture, and the mixture was heated at 90 to 150'C.
Preferably, it is carried out by stirring and heating at 100 to 140°C, and azeotropically dehydrating the reaction product 7]<. In addition, in the dehydration reaction of dicarboxylic acid-E-noamide, a different solvent, such as acetic acid, is used to react maleic anhydride with a primary amine, and the intermediate dicarboxylic acid monoamide is separated once, and then non-I ? The reaction can also be carried out in M'l raw solvent in the presence of an acid catalyst and an onium compound.

Here, the amount of maleic anhydride and primary amine used is 1.5 mol of maleic anhydride per 1 mol of primary amine. .

~1.5 mol is preferred. In addition, the non-chronic solvent should be used in an amount of 2 to 15 times as much as the primary amine. Onium compounds etc. are O01-15 for primary amines.
fflω%, especially 1.0 to 10 limb% is preferred. 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, adding more than 15 tonne will only be economically disadvantageous and will not provide any advantage.

Depending on the type of acid catalyst, 0.5
A maximum weight of ~30% is appropriate.

When the reaction is carried out under the above conditions, if the stirring is stopped after the reaction is completed, the reaction system will be separated into layers. It can be easily recovered and the amount of acid catalyst to be deposited into crystals can be reduced.

The recovered catalyst can be used as it is in the next reaction without any treatment. Thereafter, when the reaction mixture is cooled, the target N-substituted maleimide will precipitate out as crystals, which are filtered or centrifuged, and water and/or
Alternatively, a highly pure target product can be obtained by washing with alkaline water and drying. After removing the catalyst, wash with water and/or alkaline water at a humidity of about 70°C, cool to room temperature for 50 minutes,
This is possible by separating and drying the precipitated N-substituted maleimide crystals. If a higher 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 in a small amount can be neutralized with an alkali, and if necessary, the generated salt can be washed with water and then repeated for the next reaction. It can be used.

[Example] The present invention will be explained in detail with reference to Examples below.

Example 1 In a 500 d four-necked flask equipped with a condenser with water separator, a thermometer, a dropping funnel, and a stirrer, 49.
0 g (0.50 mol), xylene 1453, toluene 27.59 and n-octane 359 were charged, and aniline 44.69 (0.48 mol) was added dropwise little by little over 1 hour while stirring at a reaction temperature of 40'C. , and the reaction was continued for an additional 30 minutes at the same temperature.

In the resulting reaction mixture (1 acid 2.b!3 and Hensyl 1
Add 1 to 0.99 of ~limethylaminium chloride, stir, and boil at reflux temperature (I25 to 135'C) to 1.
The mixture was heated for 1 hour, and the reaction was continued for about 3 hours without removing the produced water.

After the reaction is complete, Ij,? Immediately after stopping the stirring, the catalyst layer separated into layers, which were separated and collected at 110'C. The amount recovered was 4.53. Thereafter, when the mixture was cooled to room temperature, pale yellow needle-shaped N-phenylmaleimide was precipitated. This was filtered, washed with a 10% aqueous sodium carbonate solution and water, and dried to obtain 63.2s of N-phenylmaleimide. It has a melting point of 88-90'C and a purity of 98% by GPC analysis.
．． It was 0%.

In addition, the amount of phenylmaleimide remaining in the reaction solution is 14
．． When combined with N-phenylmaleimide obtained as crystals at 0 g, the yield was 93% based on the aniline used. Next, using the remaining reaction solution, aniline was added dropwise to the maleic anhydride solution in the same manner as in the first reaction, and then the recovered catalyst was added and reacted.

After completion, it is filtered, washed and dried to obtain N-phenylmaleimide 78. I got og. The yield was 94% based on the raw material aniline, and the purity was 98.0%. When the reaction solution is reused, the amount of N-phenylmaleimide obtained as crystals increases because the reaction solution is already saturated with N-phenylmaleimide and the amount newly dissolved can be ignored.

Example 2 Maleic anhydride (49%) was placed in a four-necked flask similar to Example 1.
．． 0q (0.50 mol), xylene 1607, and toluene 543 were charged, and while stirring at a reaction temperature of 30°C, aniline 44. ．． 6s (0.48 mol) was added dropwise little by little over 1 hour, and the reaction was continued for another 1 hour at the same temperature. To the resulting reaction mixture (J, 9.23 g of phosphoric acid and 3.0 g of N,N-dimedyldodecylamine were added, stirred, and heated to reflux temperature (I
The mixture was heated at a temperature of 25 to 135° C.) and reacted for about 4 hours without removing the produced water.

After the reaction was completed, the mixture was cooled to 80'C, stirring was stopped for 4 minutes, and the separated catalyst layer was collected. The amount recovered was 11J1.09. Thereafter, 207 water was added at 70°C, and the mixture was washed with water at the same temperature for 30 minutes. After separating the washing water, it was cooled to room temperature, and the separated crystals were filtered and dried to obtain \-phenylmaleimide 53.03. The melting point of this thing is 88-9
As a result of GPC analysis at 0'C, the purity was 98.7%. Further, the N-phenylmaleimide remaining in the reaction solution took 25.0 seconds, and when combined with the N-phenylmaleimide obtained as crystals, the yield was 94% based on the raw material aniline.

The reaction was carried out in the same manner as the first using the recovered solvent and recovered catalyst. As a result, N-phenylmaleimi 1-79.0a was converted to 11? -ta. The yield was 95.1% based on aniline, and the purity was 98. ○? There were 6.

Example 3 In a four-loaf flask similar to Example 1 and 'li''i1, anhydrous maleic V49.09 (0,50 mol), n-ΔClan 1
4 (E7''-Preparation, Reaction' (K?r I Island 40') Aniline 44..69 (0,48-El) was added dropwise in 1 hour in y portions while stirring at li''1 On 1 Sad History 10
．． After reacting for 1 hour, 6.93% of para-1 luenesulfonic acid and 1.73% of N,N-dimedyl octadecylamine acid were added to the resulting reaction mixture. C) and reacted for about 3 hours while removing produced water.

After the reaction was completed, stirring was stopped and the separated catalyst diagram was collected.

The recovery rate was 12.09. It was then cooled to 70'C, washed at that temperature with a 10% aqueous sodium carbonate solution and water, and then cooled to air temperature. The precipitated N-phenylmaleimide was filtered off and dried. The purity of the obtained N-phenylmaleimide was 69, OtJ, and the purity as determined by GPC analysis was 98.0%. The amount of N-phenylmaleimide remaining in the reaction solution was 7.89, and when combined with 1q of N-phenylmaleimide as crystals, the yield was 93% based on the raw material aniline. Next, using the remaining reaction solution, aniline was added dropwise to the maleic anhydride solution in the same manner as in the first reaction, and then the recovered catalyst was added and reacted. Thereafter, it was filtered and dried to obtain 78.0q of N-phenylmaleimide. The yield was 94% based on the aniline used, and the purity was 98.0%.

Examples 4 to 16 The types and amounts of the onium compound, tertiary amine, and amine oxide added were changed, and other conditions were the same as in Example 1, and the catalyst and reaction solution were used repeatedly. The yield and purity are shown in Table 1.

Examples 17 to 21 Table 2 shows the results of the reaction conducted in the same manner as in Example 2 except for using the various solvents shown in Table 2. The yield and purity of N-phenylmaleimide are the results when the catalyst and solvent were reused.

Examples 22 to 32 Table 3 shows the results of the reaction conducted in the same manner as in Example 2 except that 0.48 mol of the various primary amines shown in Table 3 were used. N-
The yield and purity of '-phenylmaleimide are the results when the catalyst and solvent were reused.

Comparative Example 1 A reaction was carried out under the same conditions as in Example 1 except that benzyltrimethylammonium chloride was not added. In this case, insoluble crystals remained even after 3 hours of reaction, so an additional 5
Allowed time to react. After the reaction, an attempt was made to recover the catalyst layer, but it was difficult due to its high viscosity. The reaction solution containing the catalyst was cooled to 70° C. and washed with a 10% aqueous sodium carbonate solution and water. At this time, the washing water became cloudy. Thereafter, the mixture was cooled to room temperature, and the precipitated N-phenylmaleimide was filtered off and dried. Several sets were 19I3, and as a result of GPC analysis, the purity was 92.5%.

Next, react in the same manner as the first reaction using the remaining reaction solution,
It was filtered and dried to give 18 N-phenylmaleimide 433. The yield was 552% based on aniline, and the purity by GPC analysis was 93.0%.

Comparative Example 2 A reaction was carried out under the same conditions as in Example 1 except that xylene 1703 was used as a solvent. In this case, the reaction itself proceeded in the same manner as in Example 1a12, but after the reaction, the catalyst was uniformly dissolved in the reaction solution and could not be recovered.

[Effect of the invention 1] According to the method of the present invention, a safe nonpolar solvent is used, a sufficient reaction rate can be obtained, and the catalyst can be easily recovered.
Moreover, N-H maleimide with a single bond can be obtained at a high rate of 117. Furthermore, the recovered catalyst and solvent can be used in the next reaction without any treatment.

Claims (1)

[Claims] When producing an N-substituted maleimide by dehydrating a dicarboxylic acid monoamide obtained from maleic anhydride and a primary amine, an acid catalyst and a compound represented by the following general formulas (I) to (IV) are used. A method for producing an N-substituted maleimide, which comprises reacting in a nonpolar solvent in the presence of one or more of them, and then separating and recovering a catalyst liquid phase. [R^1R^2R^3MR^4]^+Y^- (I)
R^1R^2R^3M^+CH_2COO^- (II)
R^5R^6R^7N (III) R^5R^6R^7N→O (IV) (In general formula (I), R^1, R^2, R^3 and R^4 are their carbon numbers R^1, R^2 and R^ in general formula (II), a hydrocarbon group having a total of 10 to 80
3 is a hydrocarbon group whose total number of carbon atoms is 10 to 80, M is N, P, As or Sb, Y is Cl, Br, I,
HSO_4, ClO_4, CN, H_2PO_4, CH
_3SO_3, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or OH, and in general formulas (III) and (IV), R^
5, R^6, R^7 have a total number of carbons of 7 to 60
represents a hydrocarbon group. )