JP3155598B2 - Method for producing maleimides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing maleimides.

[0002] A maleimide compound is a compound useful as a raw material for resin materials, pharmaceuticals and agricultural chemicals, etc., and the present invention provides an advantageous production method thereof.

[0003]

2. Description of the Related Art Methods for producing maleimides have been studied for a long time. The most common method is a method for producing maleimide by subjecting maleamic acid to dehydration cyclization using a dehydrating agent such as acetic anhydride, and is disclosed, for example, in US Pat. No. 2,444,536. . That is, this is a method in which maleic anhydride is reacted with an amine compound, and the resulting maleamic acid is subjected to dehydration ring-closing imidation in the presence of acetic anhydride and sodium acetate.

This method requires an expensive acetic anhydride in an imidization reaction in an amount equivalent to that of maleamic acid,
Furthermore, since a large amount of water is required to separate and recover the maleimide generated from the liquid after the imidation reaction,
It has the disadvantage that treating large amounts of wastewater containing acetic acid is costly. For this reason, this method must be said to be too expensive for industrially producing imide compounds.

Further, as disclosed in Japanese Patent Application Laid-Open No. 53-68770, a reaction between maleic anhydride and an amine compound in an organic solvent is carried out without isolating the formed maleamic acid. There is also a method of performing a dehydration ring-closing reaction in the presence of an aprotic polar solvent such as sulfoxide and an acid catalyst.

However, this method involves the use of a large amount of expensive and toxic aprotic polar solvents such as dimethylformamide, so that the production cost of maleimide is increased, and dimethyl amide is acted upon by the action of an acid catalyst used in the reaction. Solvents such as formamide are deteriorated, resulting in large losses, and the high boiling point of these aprotic polar solvents makes it difficult to remove these solvents from the product maleimide. This is not an excellent method.

Further, as disclosed in JP-B-51-40078, the diluent has a boiling point of 80 ° C.
Heat dehydration and ring closure with the above solvents such as toluene, xylene, chlorobenzene and acid catalysts such as chlorosulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, orthophosphoric acid, pyrophosphoric acid, phosphoric acid, etc. There is also a method of distilling water out of the system by azeotropic distillation with a solvent.

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

In order to solve these problems, for example, Japanese Patent Application Laid-Open No. 62-123168 discloses a method of reusing an acid catalyst, and Japanese Patent Application Laid-Open No. 64-3167 discloses an acid and / or acid catalyst. Alternatively, there is disclosed a method for economically, safely, and easily producing a maleimide in a high yield by using a catalyst in which an amine salt obtained from a starting amine and an acid is supported on a solid carrier. These methods are superior to the above 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 catalyst activity is gradually reduced by repeating the reaction. For this reason, the productivity is remarkably reduced due to repeated use of the catalyst over a long period of time, which leads to a situation where the catalyst can no longer be used. Further, it has been pointed out that a great deal of economical cost is required for disposal of this catalyst.

Thus, an object of the present invention is a catalyst for an imidization reaction in which an amine salt obtained from an acid and / or a raw material amine and an acid is supported on a solid carrier. It is an object of the present invention to provide a method for producing a maleimide in a high yield and economically by activating a reduced catalyst.

[0012]

Means for Solving the Problems The present inventors diligently studied the cause of the above-mentioned decrease in the catalyst activity, and found that the decrease in the activity of the catalyst was caused by impurities insoluble in the solvent generated during the imidization reaction. They have been found to be deposited on the catalyst layer and cause a reduction in the surface area of the catalyst or an inhibition of the dispersion of the catalyst. In addition, the inventor has also found that impurities insoluble in such a solvent are easily dissolved in water, and thus, it is possible to easily remove these impurities by washing the catalyst with reduced activity with water. Further, when the recovered catalyst obtained by removing impurities insoluble in the solvent by washing with water is re-supported with an acid and / or an amine salt obtained from the starting amine and the acid, a new catalyst is used. As a result, they have found that maleimides can be obtained again in a high yield, and have completed the present invention.

That is, the present invention relates to a method for producing an anhydrous maleic anhydride in a water-insoluble or water-immiscible inert organic solvent in the presence of an acid and / or a starting amine and an amine salt obtained from the acid supported on a solid support. In a method for producing a maleimide by subjecting an acid and a primary amine to dehydration-condensation reaction, the catalyst used is at least one time washing the catalyst subjected to the imidization reaction with water, whereby a water-soluble component is removed from the catalyst. A method for producing a maleimide, characterized by carrying an acid and / or a starting amine and an amine salt obtained from the acid after removal.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below in more detail. Examples of the 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-carboxyphenylmaleimide, N-hydroxyphenylmaleimide, N-chlorophenylmaleimide, N
-Dimethylphenylmaleimide, N-dichlorophenylmaleimide, N-bromophenylmaleimide, N-dibromophenylmaleimide, N-trichlorophenylmaleimide, N-tribromophenylmaleimide, and the like, but are not necessarily limited thereto. is not.

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

Organic carriers can also be used, and particulate carriers such as polyfluorocarbon, polystyrene, and 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. Examples of commercially available products include diatomaceous earth as radiolite (manufactured by Showa Chemical Industry Co., Ltd.), silica gel as Carrieract, cycloid, and microbead silica gel (manufactured by Fuji Devison Chemical Co., Ltd.), and Wakogel (manufactured by Wako Pure Chemical Industries, Ltd.). ), And so on.

If a catalyst in which an acid and / or a starting amine and an amine salt obtained from the acid are supported on a solid carrier is used as the catalyst, the reaction raw material such as maleic anhydride, primary amine, or maleamic acid can be used as the catalyst. Not only can easily adjust the contact area, but also a large contact 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 by washing the catalyst subjected to the reaction at least once with water and then carrying the acid and / or the amine salt obtained from the starting amine and the acid according to the present invention comprises the steps of: However, from the economic aspect in the production of maleimides, the catalyst activity is reduced, and the yield is 1 to 1 from the initial yield.
It is preferable to carry out the process at a point where the amount is reduced by about 15 mol%, preferably about 3 to 10 mol%.

The amount of water used in the water washing depends on the amount of insolubles in the solvent adhering to the catalyst, but is generally about 1 to 10 times, preferably about 3 to 7 times the weight of the catalyst. . The type of water used at this time is industrial water,
Pure water, tap water, weak alkali or weak acid water may be used, but pure water is particularly preferable. Although the temperature at which the water washing is performed depends on the amount of water, 60 to 100 ° C. is preferably used.

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 separated in this way, and the temperature is raised to the above-mentioned temperature. At this time, stirring may or may not be performed, but it is preferable that the stirring is performed under stirring. Subsequently, the insoluble matter is dissolved and washed with water at a predetermined temperature for 10 minutes to 5 hours. After the completion of the water washing process, 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 performed in the same tank as the reaction vessel, and the separation is performed by decantation.

Thus, the acid and / or the starting amine salt and the amine salt obtained from the acid are supported and prepared on the recovered catalyst from which the catalyst deactivating component has been removed by the water washing treatment. Take out from the water treatment tank, put it in a horizontal blender, add acid and amine salt, and evaporate excess water. , And the excess water is insoluble in water or distilled out of the system as a mixture with a water-immiscible organic solvent, whereby the support can be prepared. The support is prepared in this manner. At this time, it is desirable that an acid, an amine salt, or the like is uniformly supported on the recovered catalyst as much as possible. Usually, the amount of the acid catalyst to be supported varies depending on the physical properties of the carrier used, but is 0.5 to 500% by weight, preferably 5 to 20% by weight of the carrier as the acid.
0%, particularly preferably from 10 to 100% by weight. The supported amount of the amine salt or the mixture of the amine salt and the acid is in the range of 2 to 400 mol%, preferably 20 to 200 mol%, based on the amount of the acid contained.

[0022]

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

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

(2) The cost of disposal of the catalyst can be significantly reduced without lowering the productivity.

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

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

[0027]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Example 1 300 g of orthoxylene and 30 g of diatomaceous earth (Radiolite # 200, manufactured by Showa Chemical Industry Co., Ltd.) were placed in a flask equipped with a thermometer, a cooling tube equipped with a water separator, a dropping funnel and a stirrer. Was added, 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 orthophosphoric acid and an amine salt were supported on diatomaceous earth. 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 dropping,
The reaction was continued for another 2 hours. At this time, water generated by the condensation reaction was distilled out of the system as a mixture with ortho-xylene.

After the completion of the reaction, when the stirrer was stopped, the catalyst layer and the orthoxylene layer were easily separated, and no insoluble impurities were found at both interfaces. Subsequently, the ortho-xylene layer was separated from the catalyst layer, and ortho-xylene was distilled off under reduced pressure to obtain 95 g of a tan solid.

The composition of this product was analyzed by liquid chromatography to find that the content of N-phenylmaleimide was 95.8% by weight. The yield of N-phenylmaleimide is equivalent to 97.9 mol% based on aniline charged.

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% by mole 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 by heating and stirring for 1 hour. After the completion of the water washing, only the catalyst layer was left in the flask, and only the aqueous layer was separated. The same water washing was further repeated twice, and water was distilled off under reduced pressure to obtain 38 g of a recovered catalyst.

Subsequently, 300 g of ortho-xylene was added to the recovered catalyst, and the temperature was raised to 80 ° C.
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 completion of the dropwise addition, the reaction
Continued for hours. At this time, water generated by the condensation reaction was distilled out of the system as a mixture with ortho-xylene. When the stirrer was stopped after the completion of the reaction, the catalyst layer and the orthoxylene layer were easily separated from each other, and no insoluble impurities were found at both interfaces.

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 tan solid. When the composition of this product was analyzed by liquid chromatography, the content of N-phenylmaleimide was 94.7% by weight. The yield of N-phenylmaleimide is equivalent to 97.6 mol% based on the charged aniline.

Example 2 The same operation as in Example 1 was repeated except that the carrier 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. The purity of the crystals was analyzed by liquid chromatography to be 96.3% by weight, and the yield thereof was 98.9% by mole 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 a recovered catalyst was obtained after washing 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 the reaction was carried out using this catalyst. As a result, 95.8 g of tan crystals were obtained. . The purity of the crystals was analyzed by liquid chromatography to be 95.5% by weight.
The yield corresponds to 98.4 mol% based on aniline.

Example 3 The same operation as in Example 1 was repeated, except that the carrier was supported on 30 g of silica gel (MB4B, manufactured by Fuji Devison Chemical Co., Ltd.). 6 g were obtained. The purity of the crystals was analyzed by liquid chromatography to find that 9
6.1% by weight, corresponding to a yield of 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 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 the reaction was carried out using this catalyst. As a result, 95.8 g of yellow-brown crystals were obtained. . The purity of the crystals was analyzed by liquid chromatography to be 95.9% by weight.
The yield 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 in water washing were changed. The reaction was carried out in the same manner as described above. Table 1 shows the obtained results.

[0044]

[Table 1]

[0045]

────────────────────────────────────────────────── (5) References JP-A-64-3167 (JP, A) JP-A-50-20996 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07D 207/00-207/50 B01J 31/02 102 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A water-insoluble or water-immiscible inert organic solvent, of a catalyst of amine salt derived from an acid and / or the starting amine and the acid was allowed supported on a solid carrier co
In the method of producing maleimides by subjecting maleic anhydride and a primary amine to a dehydration condensation reaction in the presence of a catalyst, the catalyst used is an imidization reaction from the catalyst by washing the catalyst used at least once with water. The solution that forms during
A method for producing a maleimide, comprising removing an insoluble impurity in a medium and supporting an acid and / or an amine salt obtained from a raw material amine and an acid. 2. The method according to claim 1, wherein the water washing is performed at 60 to 90 ° C.
A method for producing the maleimides described above.