JPH0637466B2 - Method for producing maleimides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing maleimides.
The maleimide compound is a compound useful as a raw material for resin raw materials, pharmaceuticals and agricultural chemicals, and the present invention provides an advantageous production method thereof.

(Prior Art) Methods for producing maleimides have been studied for a long time.

The most common method among them is a method for producing a maleimide by subjecting a maleamic acid to a cyclodehydration using a dehydrating agent such as acetic anhydride, which is also disclosed in, for example, U.S. Pat.No. 2,444,536. .

That is, this is a method in which maleic anhydride and an amine compound are reacted and the produced maleamic acid is subjected to dehydration ring-closure imidization in the presence of acetic anhydride and sodium acetate. This method requires expensive acetic anhydride in an amount equal to or more than that of maleamic acid in the imidization reaction, and further requires a large amount of water when separating and recovering the maleimide produced from the liquid after the imidization reaction. As a result, a large amount of waste water containing acetic acid is produced, and detoxifying the waste water has a disadvantage of requiring a great deal of cost. For this reason, it must be said that this method is too expensive for industrially producing an imide compound.

In addition, as disclosed in JP-A-53-68770, maleic anhydride and an amine compound are reacted in an organic solvent to form a maleamic acid, which is then isolated without isolation of dimethylformamide, dimethylsulfoxide and the like. There is also a method of performing a dehydration ring closure reaction in the coexistence of a protic polar solvent and an acid catalyst. However, since this method uses many aprotic polar solvents such as dimethylformamide, which is expensive and toxic, the production cost of maleimide increases, and the action of the acid catalyst used in the reaction causes dimethylformamide and the like. Since the solvent is altered, there is a problem that the loss becomes large and it is difficult to remove these solvents from the product maleimide due to the high boiling point of these aprotic polar solvents. It is not a good method.

Furthermore, as disclosed in Japanese Patent Publication No. 51-40078, a solvent having a boiling point of 80 ° C. or higher, such as toluene, xylene, chlorobenzene, etc., and chlorosulfonic acid, p-toluenesulfonic acid, benzenesulfone, etc. There is also a method in which heat dehydration ring closure is carried out together with an acid catalyst such as an acid, orthophosphoric acid, pyrophosphoric acid or phosphorous acid, and water generated at this time is distilled out of the system by azeotropic distillation with a solvent. This method
Compared with the above two methods, not only a large amount of expensive dehydrating agent such as acetic anhydride is not required, but also the produced maleimide can be easily separated and recovered.

However, in this method, chlorosulfonic acid,
A relatively large amount of expensive acid catalysts such as p-toluenesulfonic acid, benzenesulfonic acid, orthophosphoric acid, pyrophosphoric acid, and phosphorous acid are used, and the yield of maleimides is low, which is economical as an industrial manufacturing method. I am not satisfied with it.

As described above, the conventionally proposed methods for producing maleimides have many problems, and are not satisfactory for industrial implementation.

(Object of the present invention) Thus, an object of the present invention is to provide a method for producing maleimides in a high yield, at a low cost, in a safe and simple manner as compared with the above method.

(Means for Solving the Problems) The inventors of the present invention have long studied the synthetic reaction of maleimides. In particular, the inventors have intensively studied a catalyst used for a ring-closure imidization reaction in a water-insoluble or water-immiscible inert organic solvent using an acid catalyst.

According to the knowledge of the present inventors, for a ring-closing imidation reaction using a water-insoluble or water-immiscible inert organic solvent, a liquid acid insoluble in an organic solvent as a catalyst and / or a raw material amine and an acid The amine salts mentioned are the most effective.

Although the maleamic acid is present in the organic solvent layer, the above-mentioned catalyst is added to this organic solvent layer during the imidization reaction. These catalysts are insoluble in the solvent and form another liquid phase in the reactor, which is different from the organic solvent layer.

Therefore, in order for the imidization reaction to proceed in a good state, it is essential that the maleamic acid is in efficient contact with the catalyst layer.

However, even if an attempt is made to increase the contact surface area by increasing the amount of the liquid acid catalyst in order to improve the contact efficiency between the maleamic acid and the catalyst, it is not possible to achieve this object because the liquid acid catalyst particles associate. There wasn't.

Not only that, the amount of side reaction itself in the catalyst layer increases as the amount of catalyst increases, and as a result, the selectivity of the imidization reaction could not be increased.

Furthermore, it is difficult to keep the stirring conditions of the reactor constant because the acid catalyst physical properties such as viscosity and specific gravity change due to the influence of side reaction products in the acid catalyst as the acid catalyst is repeatedly used. However, the dispersion state of the acid catalyst changed each time, and the reaction state and yield could not be reproducibly reacted. In addition, since the state of separation of the acid catalyst is different each time due to such changes in the catalyst properties, there is a problem that a great amount of labor is required in separating and reusing the acid catalyst.

Therefore, the present inventors not only can easily adjust the contact interface area between the maleamic acid and the acid catalyst by supporting the acid and / or the starting amine and the amine salt obtained from the acid on diatomaceous earth and / or silica gel. Since a large contact interface area can be obtained with a small amount of catalyst, a remarkably high selectivity of imidization reaction can be obtained, and even if a catalyst is repeatedly used for the reaction, the reaction can be well reproduced,
The inventors have found that the catalyst properties are stable and can be easily separated from the reaction solution, and have completed the present invention.

That is, the present invention is characterized by using a catalyst in which an acid and / or an amine salt obtained from a starting amine and an acid are supported on diatomaceous earth and / or silica gel as a catalyst during the production of maleimides. It is a manufacturing method.

The most characteristic feature of the present invention is that instead of using liquid acid catalysts such as sulfuric acid, orthophosphoric acid, and pyrophosphoric acid alone in the ring-closure imidization reaction, so-called supported catalysts obtained by supporting these liquid acid catalysts on diatomaceous earth and / or silica gel are used. It is in use.

In some cases, the reaction may be carried out in the ring-closing imidization reaction in the presence of a metal and a stabilizer.

The maleamic acid used in the present invention is usually easily obtained by reacting maleic anhydride with primary amines, and is represented by the following general formula.

(In the formula, R is an alkyl group having 1 to 20 carbon atoms, phenyl group, benzyl group, cyclohexyl group, pyridyl group,
The quinolyl group and those having halogen substitution, carboxyl group substitution or nitro group substitution in these groups are selected. The primary amines suitable as a raw material for the maleamic acid used in the present invention are listed below.

Methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, sec-butylamine, tert-butylamine, n-hexylamine, n-
Dodecylamine, allylamine, benzylamine, cyclohexylamine, aniline, nitroaniline, aminophenol, aminobenzoic acid, anisidine, ethoxyphenylamine, monochloroaniline, dichloroaniline, toluidine, xylidine, ethylaniline and so on.

The synthesis of maleamic acid is almost stoichiometric,
1 mol of amine is preferable with respect to 1 mol of maleic anhydride, but the reaction can be carried out in the range of 0.8 to 1.5 mol, preferably 0.9 to 1.2 mol. If the amine compound is in excess of maleic anhydride, the acid catalyst used as a catalyst in the imidization reaction as it is must be used in an unnecessarily large amount, and side reactions are generated in the imidization reaction. The above range is preferable because a large amount of the product is produced and the yield of the imidization reaction becomes low.

Further, the organic solvent used in the present invention is preferably a solvent that is insoluble or immiscible in water and inert and does not participate in the reaction, for example, benzene, toluene, boiling point 50 to 50.
Petroleum fraction at 120 ℃, xylenes, ethylbenzene, isopropylbenzene, cumene, mesitylene, tert-butylbenzene, pseudocumene, trimethylhexane, octane, tetrachloroethane, nonane, chlorobenzene,
Ethylcyclohexane, petroleum fraction with a boiling point of 120-170 ℃, m
-Dichlorobenzene, sec-butylbenzene, p-dichlorobenzene, decane, p-cymene, o-dichlorobenzene, butylbenzene, decahydronaphthalene, tetrahydronaphthalene, dodecane, naphthalene, cyclohexylbenzene, boiling point 170-250 There are petroleum fractions at ℃. The amount of this solvent used is 1 to maleic acid in terms of smoothly carrying out the reaction and satisfying economic conditions.
It is used in an amount 20 times (volume), preferably 3 to 7 times.

Further, those having a boiling point suitable for the reaction conditions are selected in consideration of the solubility, price, and handleability of the maleimides. Considering the separation of the maleimides and the solvent after completion of the reaction, it may be advantageous to use a solvent having a low boiling point and carry out the reaction under pressure.

As a catalyst, an amine salt obtained by neutralizing a monobasic acid or polybasic acid such as sulfuric acid, orthophosphoric acid, metaphosphoric acid, and pyrophosphoric acid and / or an amine which is a raw material in the production of maleimides is used. Those supported on soil and / or silica gel are used.

The shape of diatomaceous earth and silica gel as a carrier is not particularly limited, and may be, for example, a powdery material, a granular material obtained by granulating or classifying it, or a honeycomb shape.

Examples of commercial products of diatomaceous earth and silica gel include radiolite (manufactured by Showa Chemical Industry Co., Ltd.) as diatomaceous earth, and carrier act, siloid, as silica gel.
Examples thereof include microbead silica gel (manufactured by Fuji Devison Chemical Co., Ltd.) and Wako gel (manufactured by Wako Junyaku Kogyo Co., Ltd.).

Usually, the amount of the acid catalyst supported on the carrier varies depending on the physical properties of the carrier used, but is 0.5 to 500% by weight with respect to the carrier as an acid,
Amounts of preferably 5 to 200% by weight, particularly preferably 10 to 100% by weight.

Further, as a method for supporting, any of generally used impregnation method, spraying method and the like can be adopted, and the catalyst may be directly supported on the carrier or may be carried in an organic solvent or an aqueous solution. .

When an amine salt obtained by a neutralization reaction between a starting amine and an acid is used as a catalyst, either alone or in the form of a mixture with an acid, the acid catalyst may be supported on a carrier and then reacted with the amine. A mixture of salt and acid may be prepared in advance and then supported. However, when the amine salt is used alone, since the amine salt is solid at room temperature, it needs to be supported in the form of an aqueous solution.

The amount of these catalysts used is in the range of 2 to 400 mol%, preferably 20 to 200 mol%, based on the maleic acid contained as the acid content. Further, some or all of the acid as a catalyst may be neutralized with an amine.

The supported catalyst may be used by adding it in the form of a powdery catalyst to a stirring reaction vessel, or by filling it in the form of a granular catalyst in a flow reaction tube and using it as a fixed bed.

In some cases, a metal-containing compound and a stabilizer may be allowed to react in the reaction system. The metal-containing compound used at this time is at least one metal oxide, acetate, maleate, succinate, selected from the group consisting of zinc, chromium, barium, cobalt, nickel, iron and aluminum, It is selected from nitrates, phosphates, chlorides, sulfates and the like, and of these, zinc acetate is particularly effective. The amount of these used is 0.005 to 0.5 mol% as a metal with respect to 1 mol of maleamic acid,
It is preferably 0.01 to 0.1 mol%.

Further, as a stabilizer, methoxybenzoquinone, p-methoxyphenol, phenothiazine, hydroquinone, alkylated diphenylamines, methylene blue, tert-
Butylcatechol, tert-butylhydroquinone, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionates, mercaptobenzimidazoles, triphenylphosphites, alkylphenols, alkylbisphenols, etc. Used.

The effect of these stabilizers plays a role of allowing the maleimide generated by the imidization reaction to exist stably without being deteriorated even at high temperature in the imidization reaction.

As for the amount of addition, it is not desirable to add a very small amount because the effect is thin, and conversely, an excessive addition causes a problem of inclusion in the product. Therefore, the amount of these used is 0.005-0.5 mol% with respect to 1 mol of maleamic acid.

As a method for carrying out the present invention, first, to a solution of maleic anhydride in an organic solvent, an amine compound is added, and maleic acid is obtained by reacting at 150 ° C. or lower, preferably at 30 to 120 ° C. for 15 to 120 minutes. . Next, a mixed solvent of the above salt and acid or a mixed catalyst layer of salt and acid separated from the reaction system is added without isolating maleamic acid.
If necessary, a metal-containing compound and / or a stabilizer may be added to the mixture at 120 to 250 ° C, preferably 130 to 220 ° C for 1 hour to 1
After heating for 5 hours, the formed water is distilled off to the outside of the system as a mixture with the solvent to carry out the reaction continuously or is distilled off to the outside of the system after completion of the reaction in a batchwise manner to give a high yield of maleimides. Can be manufactured.

(Effects of the Invention) The present invention has been described above, but the advantages obtained by the present invention are as follows.

Highly pure maleimides because a catalyst system in which an acid and / or an amine salt obtained from a raw material amine and an acid are supported on diatomaceous earth and / or silica gel has a high catalytic activity for ring-closure imidization reaction. Can be obtained in high yield.

Since the catalyst is supported on diatomaceous earth and / or silica gel, the reaction solution and the catalyst can be easily separated, so that the reaction can be easily continuous and the productivity of the process can be greatly improved.

The catalyst loss is small and the catalyst cost is almost negligible.

As described above, according to the present invention, maleimides can be manufactured inexpensively, safely and easily.

(Example) Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 20 g of orthophosphoric acid was added to a 200 cc beaker, and then 30 g of diatomaceous earth (Radiolite # 200 manufactured by Showa Chemical Industry Co., Ltd.) was added to support diatomaceous earth with orthophosphoric acid.

A flask having a thermometer, a cooling tube equipped with a water separator, a dropping funnel and a stirrer was charged with a solution prepared by dissolving 55 g of maleic anhydride in 50 g of xylene. Next, the temperature inside the flask was adjusted to 80 ° C., and a solution of 50 g of aniline dissolved in 400 g of xylene was added little by little over 30 minutes to synthesize a xylene slurry solution of N-phenylmaleamic acid.

The catalyst prepared in advance in a beaker was added to the slurry thus obtained, and the mixture was reacted at 140 ° C. for 3 hours.

After the reaction was completed, the reaction solution was separated from the catalyst layer. After that 80
After cooling to ℃ and washing with water, xylene was distilled off under reduced pressure to obtain 83 g of N-phenylmaleimide crystals. The purity of this crystal was measured by liquid chromatography and found to be 87.4% by weight. The yield of this crystal was based on aniline.
Equivalent to 78.0%.

Example 2 A crystal of N-phenylmaleimide was prepared in the same manner as in Example 1 except that 0.034 g of zinc acetate and 0.01 g of copper dibutyldithiocarbamate were added during the imidization reaction.
I got 93g. The purity of this crystal was measured by liquid chromatography and found to be 94.3% by weight, and the yield of this crystal corresponded to 94.3 mol% based on aniline.

Example 3 Xylene 100g and orthophosphoric acid 2 in a 300cc Meyer flask
0 g was dispersed. Next, the same diatomaceous earth as used in Example 1 was introduced to support orthophosphoric acid on the diatomaceous earth. Subsequently, 9.5 g of aniline was reacted.

When the same operation as in Example 2 was carried out except that this was used as a catalyst for the imidization reaction, 92 g was obtained.

The purity of this crystal was measured by liquid chromatography and found to be 98.5% by weight, and the yield of this crystal corresponded to 97.5 mol% based on aniline.

After completion of the reaction, the next imidation reaction was repeated 20 times under the above conditions while the catalyst was left in the reactor. The reaction yield of the 20th reaction was 98.1 mol%, and the properties of the catalyst after the reaction were the same as those of the first reaction.

Comparative Example 1 The same operation as in Example 1 was repeated except that orthophosphoric acid was not supported on diatomaceous earth in Example 1. As a result, 82 g of N-phenylmaleimide crystals were obtained. The purity of this crystal was measured by liquid chromatography and found to be 74.8% by weight, and the yield of this crystal corresponded to 66.0 mol% based on the starting aniline.

Comparative Example 2 The same operation as in Example 2 was repeated except that orthophosphoric acid was not supported on diatomaceous earth in Example 2 to obtain 85 g of N-phenylmaleimide crystals.

The purity of this crystal was measured by liquid chromatography and found to be 90.2% by weight, and the yield of this crystal was equivalent to 80.5 mol% based on aniline.

Comparative Example 3 The same operation as in Example 3 was repeated except that orthophosphoric acid was not supported on diatomaceous earth in Example 3, to obtain 90 g of N-phenylmaleimide crystals. The purity of this crystal was measured by liquid chromatography to be 9
1.7% by weight, which is 88.8 mol% based on aniline
Equivalent to.

Example 4 60 g of orthophosphoric acid was added to a 300 cc Meyer flask, and 60 g of granular silica gel carrier (Carrierct-30 Fuji Debison Chemical Co., Ltd.) was added and stirred to allow the acid to be supported on the carrier.

Subsequently, 100 g of ortho-xylene was added and 37 g of cyclohexylamine was added while cooling the Meyer flask in a water bath.
Was added dropwise, and a part of the supported acid was used as an amine salt.

On the other hand, 100 g of ortho-xylene was charged into a flask equipped with a thermometer, a cooling tube equipped with a water separator, a dropping funnel and a stirrer, and 100 g of maleic anhydride was added to bring the temperature inside the flask to 100 ° C. to give maleic anhydride. The acid dissolved.

Then, 600 g of ortho-xylene and 10 of cyclohexylamine
The total amount of the solution in which 0 g was dissolved was added dropwise over 1 hour under stirring, and N-
A slurry of cyclohexylmaleamic acid oxoxylene was synthesized.

Next, the above supported catalyst and the copper dibutyldithiocarbamate (0.1 g) were added to this slurry liquid, and the mixture was heated and stirred.
The temperature was maintained at 143 ° C., and the reaction was carried out for 7 hours while distilling out the water produced by the reaction together with oxoxylene.

After completion of the reaction, N-cyclohexylmaleimide in the reaction solution was analyzed by gas chromatography to determine the yield.
It was 97.8 mol%.

Example 5 100 g of sulfuric acid was added to a 500 cc beaker, and 200 g of silica gel (Wako Pure Chemicals Wako Gel-C 100) was added and stirred to support the acid catalyst on the silica gel. On the other hand, a reactor having a thermometer, a stirrer and a water separator attached to the glass flask of No. 1 was prepared.

Next, a solution prepared by dissolving 53 g of maleic anhydride powder in 50 g of p-cymene was charged into the above reactor. Then, the temperature inside the reactor was adjusted to 130 ° C., and a solution of 40 g of n-butylamine dissolved in 400 g of p-cymene was gradually added dropwise over 30 minutes.
A slurry liquid of (n-butyl) maleamic acid was synthesized.

To the thus obtained slurry liquid, the above-mentioned supported catalyst whole amount, zinc acetate 0.034 g and p-methoxyphenol 0.065 g were added, and reacted at a temperature of 180 ° C. for 1 hour while distilling generated water together with p-cymene. .

After the reaction was completed, the concentration of N- (n-butyl) maleimide in the reaction solution was measured to determine the reaction yield, which was 80.4 mol% with respect to the raw material n-butylamine.

Example 6 Ortho-xylene acid 10 in a 300 cc Meyer flask
0 g and 20 g of orthophosphoric acid were dispersed. Next, diatomaceous earth (Radiolite # 200, Showa Chemical Industry Co., Ltd.)
(Manufactured by K.K.), and orthophosphoric acid was supported on diatomaceous earth, and subsequently reacted with 9.5 g of aniline to prepare an aniline salt-supported catalyst.

A flask having a thermometer, a cooling tube equipped with a water separator, a dropping funnel and a stirrer was charged with a solution prepared by dissolving 55 g of maleic anhydride in 50 g of ortho-xylene. Next, the temperature inside the flask was adjusted to 80 ° C., and aniline 5 was added.
A solution prepared by dissolving 0 g in 400 g of ortho-xylene was added little by little over 30 minutes to synthesize a slurry solution of N-phenylmaleamic acid.

0.034 g of zinc acetate, 0.1 g of copper dibutyldithiocarbamate, and the catalyst prepared above were added to the thus obtained slurry liquid, and the mixture was reacted at 140 ° C. for 3 hours.

After the reaction was completed, the reaction solution was separated from the catalyst layer. The reaction solution is 8
After cooling to 0 ° C. and washing with water, orthoxylene was distilled off under reduced pressure, and 92 g of N-phenylmaleimide crystals were added. The purity of this crystal was measured by liquid chromatography and found to be 98.5% by weight, and the yield of this crystal corresponded to 97.5 mol% with respect to aniline.

After the completion of the reaction, the catalyst was left in the reactor and the next imidation reaction was repeated twice under the above conditions. The reaction yield of the second reaction was 97.8 mol%, the third yield was 98.0 mol%,
The properties of the catalyst after the reaction were the same as in the first reaction.

Comparative Example 4 In Example 6, instead of diatomaceous earth as a carrier, silicon carbide (SiC: 400 mesh, Aldrich) was used.
The reaction was carried out in the same manner as in Example 6 except that the product manufactured by the manufacturer was used.

The amount of crystals of N-phenylmaleimide produced was 90 g. The purity of this crystal was measured by liquid chromatography and found to be 92.2% by weight, and the yield of this crystal was equivalent to 89.2 mol% based on aniline.

When the imidization reaction was repeated, the yield of the second reaction was 78.5 mol% and the yield of the third reaction was 62.8 mol%, and it was confirmed that the yield was clearly decreased. In addition, the properties of the catalyst after the completion of the first reaction were that most of the orthophosphoric acid had desorbed and the silicon carbide powder adhered to the wall surface as a sticky substance, and was not dispersed in the reaction solution in the second and subsequent reactions.

Comparative Example 5 In Example 6, instead of diatomaceous earth as the carrier, alumina (CATAPAL G, VISTA CHEMI) was used.
The reaction was carried out in the same manner as in Example 6 except that (from CAL) was used.

The amount of crystals of N-phenylmaleimide produced was 78 g. The purity of this crystal was measured by liquid chromatography and found to be 71.3% by weight, and the yield of this crystal was 59.8 mol% based on aniline.

When the imidization reaction was repeated, the reaction yield of the second reaction was 47.5 mol% and the yield of the third reaction was 38.1 mol%, and it was confirmed that the yield was clearly decreased. In addition, the properties of the catalyst after the first reaction became a viscous slurry, and the interface was very unclear. This tendency became remarkable as the number of times increased.

Comparative Example 6 The reaction was performed in the same manner as in Example 6 except that activated carbon (BACS, manufactured by Taiyo Kaken Co., Ltd.) was used as the carrier instead of diatomaceous earth.

The amount of crystals of N-phenylmaleimide produced was 80 g. The purity of this crystal was measured by liquid chromatography to be 74.6% by weight, and the yield of this crystal was equivalent to 64.2 mol% with respect to aniline.

When the imidization reaction was repeated, the reaction yield of the second reaction was 59.3 mol% and the yield of the third reaction was 52.7 mol%, and it was confirmed that the yield was clearly decreased. Moreover, the properties of the catalyst after the completion of the initial reaction became a viscous slurry. This tendency became remarkable as the number of times increased.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Akio Fukui, Inventor Akio Fukui, 992, Okihama, Aki-ku, Himeji-shi, Hyogo Prefecture, Himeji Research Laboratories, Nippon Catalytic Chemical Industry Co., Ltd. Address No. 1 Japan Catalysis Chemical Industry Co., Ltd. Himeji Research Laboratories In-house referee body Chief referee Koichi Isobe Judge Toshiaki Yoshida Judge Miyasaka Hatsuo (56) Reference JP 61-106554 (JP, A) JP Sho 61-204166 (JP, A) JP-A-61-85359 (JP, A) JP-B-45-16941 (JP, B1)

Claims (1)

[Claims] 1. An amine obtained from an acid and / or a raw material amine and an acid as a catalyst in producing a maleimide by dehydration ring closure of a maleamic acid obtained from maleic anhydride and a primary amine in an organic solvent. A method for producing maleimides, which comprises using a catalyst in which a salt is supported on diatomaceous earth and / or silica gel.