JPH05213869A - Production of maleimides - Google Patents

Abstract

PURPOSE:To obtain a method for economically producing maleimides in high yield by activating a catalyst deteriorated in activity as a result of its repeated use for a long period. CONSTITUTION:The objective method for producing maleimides is characterized in that a catalyst to be used is obtained by washing a catalyst at least once used for reaction with water, thereby removing water-soluble components from the catalyst and then supporting an amine salt prepared from an acid and/or a raw material amine and the acid on a solid carrier in a method for subjecting maleic anhydride and a primary amine to dehydration condensing reaction in the presence of the catalyst prepared by supporting the amine salt obtained from the acid and/or the raw material amine and the acid on the solid carrier in a water-insoluble or a water-immiscible inert organic solvent and producing the maleimides.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing maleimides.

The maleimide compound is a compound useful as a raw material for resins, raw materials for pharmaceuticals and agricultural chemicals, and the present invention provides an advantageous production method thereof.

[0003]

2. Description of the Related Art A method for producing maleimides has 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 US 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 the imidization reaction in an amount equal to or more than that of maleamic acid.
Furthermore, since a large amount of water is required to separate and collect the maleimide produced from the liquid after the imidization reaction,
It has the drawback of being very expensive to treat large amounts of wastewater containing acetic acid. For this reason, this method must be said to be too expensive for industrially producing an imide compound.

Further, as disclosed in JP-A-53-68770, dimethylformamide and dimethylformamide are prepared without reacting maleic anhydride with an amine compound in an organic solvent to isolate the produced maleamic acid. There is also a method of performing a dehydration ring-closing reaction in the coexistence of an aprotic polar solvent such as sulfoxide and an acid catalyst.

However, this method uses a large amount of an aprotic polar solvent such as dimethylformamide, which is expensive and toxic, so that the production cost of maleimide is high, and the action of the acid catalyst used in the reaction causes the reaction of dimethyl. Since the solvent such as formamide is altered, the loss becomes large, and it is difficult to remove these solvents from the product maleimide because the boiling points of these aprotic polar solvents are high. Therefore, it is not an excellent method.

Furthermore, as disclosed in the specification of Japanese Patent Publication No. 51-40078, the boiling point is 80 ° C. as a diluent.
Heat dehydration ring closure is carried out together with the above solvent such as toluene, xylene, chlorobenzene and an acid catalyst such as chlorosulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, orthophosphoric acid, pyrophosphoric acid, phosphorous acid, etc. There is also a method of distilling water out of the system by azeotropic distillation with a solvent.

However, this method uses a relatively large amount of expensive acid catalysts such as chlorosulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, orthophosphoric acid, pyrophosphoric acid and phosphorous acid, and The yield of maleimides is also low and is not economically satisfactory as an industrial production method.

To solve these problems, for example, JP-A-62-123168 discloses a method of reusing an acid catalyst, and JP-A-64-3167 discloses an acid and / or acid catalyst. Also disclosed is a method for producing maleimides in a high yield economically, safely and simply by using a catalyst in which an amine salt obtained from a starting amine and an acid is supported on a solid support. It can be said that these methods are superior to the above-mentioned methods in that the productivity of the process can be significantly improved with a small catalyst cost.

[0010]

However, even in these methods, there is a problem that the catalytic activity is gradually lowered by repeating the reaction. For this reason, the productivity is remarkably reduced due to repeated use of the catalyst for a long period of time, which leads to a situation in which the catalyst can no longer be used. Further, it has been pointed out that the disposal of the catalyst causes a great cost economically.

Thus, the object of the present invention relates to a catalyst for imidation reaction in which an acid and / or an amine salt obtained from a starting amine and an acid are supported on a solid support, and the activity of the catalyst is improved as a result of repeated use of the catalyst over a long period of time. An object of the present invention is to provide a method for producing maleimides in high yield and economically by activating the lowered catalyst.

[0012]

Means for Solving the Problems The inventors of the present invention have made extensive studies on the cause of the decrease in the above-mentioned catalytic activity. As a result, the decrease in the catalytic activity is caused by impurities insoluble in the solvent generated during the imidization reaction in the catalyst or It has been found that the cause is that they are deposited on the catalyst layer to reduce the surface area of the catalyst or hinder the dispersion of the catalyst. It was also found that impurities that are insoluble in such a solvent are easily dissolved in water, so that these impurities can be easily removed by washing the catalyst with reduced activity with water. Furthermore, when a new catalyst is used by carrying again the acid and / or the amine salt obtained from the starting amine and the acid on the recovered catalyst obtained by removing impurities insoluble in the solvent by washing with water. As a result, it was discovered that maleimides can be obtained in high yield, and the present invention has been completed.

That is, according to the present invention, in the presence of a catalyst in which an acid and / or a starting amine and an amine salt obtained from an acid are supported on a solid support in the presence of a water-insoluble or water-immiscible inert organic solvent, maleic anhydride is used. In the method for producing a maleimide by subjecting an acid and a primary amine to a dehydration condensation reaction, the catalyst used is at least once washed with water to wash the catalyst, and the water-soluble component is removed from the catalyst. A method for producing maleimides, characterized in that after being removed, it is supported with an acid and / or an amine salt obtained from a starting amine and an acid.

[0014]

DETAILED DESCRIPTION The present invention will be described in more detail below. Examples of maleimides produced by the method of the present invention include N-methylmaleimide, N-ethylmaleimide, N-hexylmaleimide, N-octylmaleimide, N-dodecylmaleimide, N-benzylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-nitrophenylmaleimide, N-methoxyphenylmaleimide, N-methylphenylmaleimide,
N-carboxyphenyl maleimide, N-hydroxyphenyl maleimide, N-chlorophenyl maleimide, N
-Dimethylphenylmaleimide, N-dichlorophenylmaleimide, N-bromophenylmaleimide, N-dibromophenylmaleimide, N-trichlorophenylmaleimide, N-tribromophenylmaleimide, etc., but not necessarily limited to these is not.

As the acid, a monobasic acid or polybasic acid such as sulfuric acid, orthophosphoric acid, metaphosphoric acid or pyrophosphoric acid is used. Solid carriers include natural minerals such as kaolins, clay, talc, chalk, quartz, bentonite, montmorillonite, diatomaceous earth, etc .; synthetic minerals such as highly dispersed silicic acid, alumina, silicates, activated carbon, gypsum, red iron oxide, oxidation. Titanium, silica, silica-alumina, zirconium oxide and the like; natural rocks such as calcite, marble, pumice, sepiolite and dolomite are used. These inorganic carriers are used in the form of a powdery material, a granular material obtained by granulating and classifying it, or a honeycomb shape.

It is also possible to use an organic carrier, and a granular carrier such as polyfluorocarbon, polystyrene or phenol resin can also be used. Particularly good results can be obtained when the carrier is porous, such as diatomaceous earth, silica gel and the like. For example, examples of commercially available products include radiolite (manufactured by Showa Chemical Industry Co., Ltd.) as diatomaceous earth, carrier act, cycloid, microbead silica gel (manufactured by Fuji Davison Chemical Co., Ltd.) as silica gel, and Wakogel (manufactured by Wako Pure Chemical Industries, Ltd.). ), Etc.

When a catalyst in which an amine salt obtained from an acid and / or a raw material amine and an acid is supported as a catalyst is used, a reaction raw material such as maleic anhydride, a primary amine and a maleamic acid and a catalyst are used. Not only can the contact surface area of the catalyst be easily adjusted, but a large contact surface area can be obtained with a small amount of catalyst, so that a remarkably high selectivity of the imidization reaction can be obtained.

The method of activating the catalyst according to the present invention by washing the catalyst which has been subjected to the reaction at least once with water and then supporting the acid and / or the amine salt obtained from the starting amine and the acid in any state However, the catalytic activity decreases from the economical aspect in the production of maleimides, and the yield is 1 to 1 from the initial yield.
It is preferably carried out at the point of a decrease of about 15 mol%, preferably about 3 to 10 mol%.

The amount of water used for washing with water depends on the amount of insoluble matter in the solvent adhering to the catalyst, but it is generally 1 to 10 times by weight, preferably 3 to 7 times by weight that of the catalyst. .. The types of water used at this time are industrial water,
Pure water, tap water, weak alkali or weakly acidic water may be used, but pure water is particularly preferable. The temperature at which the water washing is performed depends on the amount of water, but is preferably 60 to 100 ° C.

Next, an embodiment of the present invention will be specifically described. After completion of the reaction, the catalyst and the reaction solution are separated by filtration, decantation, or the like. A predetermined amount of water is added to the catalyst thus separated, and the temperature is raised to the above temperature. At this time, it may be stirred or not, but it is preferable to carry out the stirring. Subsequently, the insoluble matter is dissolved and washed with water at a predetermined temperature for 10 minutes to 5 hours. After the water washing treatment is completed, the catalyst and water are separated again by filtration, decantation and the like. By repeating this operation 1 to 5 times, the substance that reduces the activity of the catalyst is completely removed. In a particularly preferred embodiment, the series of operations is carried out in the same vessel as the reaction kettle and the separation is done by decantation.

Thus, an acid and / or an amine salt as a raw material and an amine salt obtained from an acid are prepared and supported on the recovered catalyst from which the catalyst deactivating component has been removed by washing with water. It may be carried out by taking it out from the washing treatment tank and putting it in a horizontal blender to evaporate excess water by adding an acid and an amine salt, or without removing it, acid, amine salt, etc. in the washing treatment tank. It is also possible to carry out preparation by adding the above to distill excess water out of the system as a mixture with an organic solvent which is insoluble or immiscible in water. The carrier is prepared in this manner, and at this time, it is desirable that the recovered catalyst be uniformly supported with the acid, amine salt and the like. Usually, the amount of the acid catalyst supported varies depending on the physical properties of the carrier used, but as an acid, it is 0.5 to 500% by weight, preferably 5 to 20% by weight relative to the carrier.
An amount of 0%, particularly preferably 10 to 100% by weight. The amount of the amine salt or the mixture of the amine salt and the acid supported is in the range of 2 to 400 mol%, preferably 20 to 200 mol%, based on the acid content contained, based on the maleamic acid.

[0022]

The present invention has been described above. The advantages obtained by the present invention are as follows.

(1) Since the activity is lowered and the discarded catalyst can be activated, the catalyst can be used semipermanently.

(2) It is possible to significantly reduce the cost of the catalyst disposal process without lowering the productivity.

(3) There is no fear of environmental damage due to catalyst disposal.

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

[0027]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention.

(Example 1) In a flask equipped with a thermometer, a cooling tube equipped with a water separator, a dropping funnel and a stirrer, 300 g of orthoxylene and 30 g of diatomaceous earth (Radiolite # 200, manufactured by Showa Chemical Industry Co., Ltd.) Then, the internal temperature was raised to 80 ° C., 20 g of orthophosphoric acid (containing 3 g of water) and 2 g of aniline were added, and diatomaceous earth was loaded with orthophosphoric acid and an amine salt. Next, the internal temperature was raised to 135 ° C., and 50 g of aniline and 63 g of maleic anhydride melted at 70 ° C. were added dropwise over 2 hours. After finishing the dropping
The reaction was continued for another 2 hours. At this time, the water generated by the condensation reaction was distilled out of the system as a mixture with orthoxylene.

When the stirrer was stopped after completion of the reaction, the catalyst layer and the orthoxylene layer were easily separated, and no insoluble impurities were found at the interfaces between them. Subsequently, the orthoxylene layer was separated from the catalyst layer, and the orthoxylene was distilled off under reduced pressure to obtain 95 g of a yellowish brown solid.

When the composition of this product was analyzed by liquid chromatography, the N-phenylmaleimide content was 95.8% by weight. The yield of N-phenylmaleimide corresponds to 97.9 mol% based on the charged aniline.

When the above reaction was repeated 200 times, insoluble impurities were found at the interface between the catalyst layer and the orthoxylene layer after the reaction was completed, and separation was difficult. The yield of N-phenylmaleimide was 93.2 mol% based on the charged aniline.

Then, the catalyst was separated, washed with ortho-xylene, and the ortho-xylene was distilled off under reduced pressure to obtain 63 g of the catalyst.

Next, 63 g of this catalyst and 1 part of water were placed in the same flask.
50 g was added and the internal temperature was adjusted to 80 ° C. This slurry liquid was washed with 1 hour of heating and stirring. After the completion of washing with water, only the catalyst layer was left in the flask, and only the water layer was separated. The same washing with water was repeated twice more, and water was distilled off under reduced pressure to obtain 38 g of recovered catalyst.

Subsequently, 300 g of orthoxylene was added to the recovered catalyst and the temperature was raised to 80 ° C. to obtain orthophosphoric acid 20.
g (containing 3 g of water) and 2 g of aniline were added to prepare a catalyst supporting orthophosphoric acid and an amine salt.

Next, the internal temperature was raised to 135 ° C., and 50 g of aniline and 63 g of maleic anhydride melted at 70 ° C.
Was added dropwise over 2 hours. After the dropping is completed, the reaction is continued to 2
I continued for hours. At this time, the water generated by the condensation reaction was distilled out of the system as a mixture with orthoxylene. When the stirrer was stopped after the completion of the reaction, the catalyst layer and the orthoxylene layer were easily separated, and no insoluble impurities were found at the interface between them.

Subsequently, the orthoxylene layer was separated from the catalyst layer, and the orthoxylene was distilled off under reduced pressure to obtain 95.8 g of a yellowish brown solid. When the composition of this product was analyzed by liquid chromatography, the N-phenylmaleimide content was 94.7% by weight. The yield of N-phenylmaleimide corresponds to 97.6 mol% based on the charged aniline.

Example 2 The same procedure as in Example 1 was repeated except that the carrier in Example 1 was changed to 30 g of silica gel (Wakogel C-100, manufactured by Wako Pure Chemical Industries, Ltd.). 95.5 g of crystals were obtained. When the purity of this crystal was analyzed by liquid chromatography, it was 96.3% by weight, and the yield of this crystal was equivalent to 98.9 mol% based on aniline.

When the reaction was repeated 200 times, the yield was 92.3 mol% based on aniline, the catalyst was 59 g, and 37 g of recovered catalyst was obtained after washing and recovery with water.

Using this recovered catalyst, a catalyst supporting orthophosphoric acid and an amine salt was prepared in the same manner as in Example 1, and a reaction was carried out using this catalyst, to obtain 95.8 g of yellowish brown crystals. .. When the purity of this crystal was analyzed by liquid chromatography, it was found to be 95.5% by weight.
The yield of this product corresponds to 98.4 mol% based on aniline.

Example 3 The same operation as in Example 1 was repeated except that the carrier in Example 1 was loaded on 30 g of silica gel (MB4B, manufactured by Fuji Davisson Chemical Co., Ltd.), and yellowish brown crystals 95. I got 6g. When the purity of this crystal was analyzed by liquid chromatography, it was found to be 9
It was 6.1% by weight, and the yield of this product was 98.8 mol% based on aniline.

When the reaction was repeated 200 times, the yield was 91.8 mol% based on aniline, the catalyst was 62 g, and 37 g of recovered catalyst was obtained after washing and recovery with water.

Using this recovered catalyst, a catalyst supporting orthophosphoric acid and an amine salt was prepared in the same manner as in Example 1, and a reaction was carried out using this catalyst, to obtain 95.8 g of yellowish brown crystals. .. When the purity of this crystal was analyzed by liquid chromatography, it was found to be 95.9% by weight.
The yield of this product corresponds to 98.8 mol% based on aniline.

(Examples 4 to 7) Example 1 was repeated except that silica gel (Wakogel C-100, manufactured by Wako Pure Chemical Industries, Ltd.) was used as a carrier and the temperature and the amount of water used for washing were changed. The reaction was performed in the same manner as in. The results obtained are shown in Table 1.

[0044]

[Table 1]

[0045]

Claims (1)

[Claims] 1. Maleic anhydride in the presence of a catalyst in which an acid and / or an amine salt obtained from a starting amine and an acid are supported on a solid support in a water-insoluble or water-immiscible inert organic solvent. In a method for producing a maleimide by dehydration condensation reaction of a primary amine with a primary amine, the catalyst used is a catalyst used in the reaction after washing with water to remove water-soluble components from the catalyst,
A method for producing a maleimide, comprising supporting an acid and / or an amine salt obtained from a starting amine and an acid.