JPS6263562A - Production of maleimide - Google Patents

Abstract

PURPOSE:To safely obtain a maleimide in high yield, by cyclizing and imidating a maleinamic acid in the presence of a metal-containing compound and stabilizer in an organic solvent capable of forming an azeotropic mixture with water within a specific temperature range while removing the formed water as the azeotropic mixture to the outside of the system. CONSTITUTION:A maleinamic acid expressed by the formula (R is alkyl, phenyl, pyridyl, etc.) is cyclized in the presence of 10-30mol%, based on the raw material, acid catalyst, e.g. sulfuric acid or pyrophosphoric acid, a metal-containing compound, e.g. Zn, Cr, Pd or Al, and stabilizer, e.g. methoxybenzoquinone, in an organic solvent capable of forming an azeotropic mixture with water, e.g. benzene or octane, while heating at 170-250 deg.C for 1-15hr to afford the aimed maleimide. The formed water is removed to the outside of the system by azeotropic distillation. USE:A raw material for resins, medicines and agricultural chemicals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing maleimides.

Maleimide compounds are useful compounds as raw materials for resin raw materials, medicines, agricultural chemicals, etc., and the present invention provides an advantageous method for producing them.

[Conventional technology]

Methods for producing maleimides have been studied for a long time.

The most common method is to produce maleimide by dehydrating maleamic acid using a dehydrating agent such as acetic anhydride, for example, as disclosed in US Pat.
It is also disclosed in the specification of No. 36.

That is, it is a method in which maleic anhydride and an amine compound are reacted, and the resulting maleamic acid is dehydrated and ring-closing imidized in the presence of acetic anhydride and sodium acetate. This method requires more than the equivalent amount of expensive acetic anhydride to maleamic acid in the imidization reaction, and also requires a large amount of water to separate and recover the maleimide produced from the liquid after the imidization reaction. Therefore, it has the disadvantage that it requires a large amount of cost to treat a large amount of wastewater containing acetic acid. For these reasons, this method is too expensive to industrially produce imide compounds.

On the other hand, a method that does not use a chemical dehydrating agent such as acetic anhydride is disclosed in Japanese Patent Publication No. 51-40078. That is, thermal dehydration and ring closure are carried out with a solvent such as toluene, xylene, or chlorobenzene having a boiling point of 80°C or higher as a diluent and an acid catalyst such as sulfur trioxide, sulfuric acid, orthophosphoric acid, and the water produced at this time is subjected to azeotropic reaction with the solvent. This method involves distilling it out of the thread. This method is superior to the method using acetic anhydride in that it not only does not require an expensive dehydrating agent such as acetic anhydride, but also that the maleimide produced is easy to separate and recover.

However, a major problem is that the yield of the imidization reaction is lower than that of the method using acetic anhydride.

The reason for this is that compared to the method of imidization using acetic anhydride, the method of imidization by heating dehydration in the above solvent has a higher reaction temperature and is more likely to cause side reactions. The only thing that can be changed is
Another possible reason is that the generated maleimide itself is thermally unstable, so that the generated maleimide deteriorates during the reaction.

Also, as in the specification of JP-A No. 53-68770,
A method in which maleic anhydride and an amine compound are reacted in an organic solvent, and the resulting maleic acid amide is subjected to a dehydration ring-closing reaction in the coexistence of an aprotic polar solvent such as dimethylformamide or dimethyl sulfoxide and an acid catalyst without isolating the maleic acid amide. There is also.

According to this method, the yield is improved compared to the second method. However, the manufacturing cost of maleimide is high due to the use of a large amount of expensive and toxic aprotic polar solvents such as dimethylformamide, and the effects of the acid catalyst used in the reaction deteriorate the quality of solvents such as dimethylformamide. However, due to the high boiling point of these aprotic polar solvents, it is difficult to remove them from the maleimide product. .

[Problem that the invention seeks to solve]

In this way, the currently existing methods for producing maleimides are
Many problems have been pointed out, and it is not satisfactory for industrial implementation.

The purpose of the present invention is to (1) have a high reaction yield, (2) be a safe and moderately efficient method, (3) be able to obtain maleimides with high purity, and (4) be able to produce them at low cost. An object of the present invention is to provide a satisfactory method for producing maleimides.

[Means for solving problems]

The present inventors have long continued research on synthetic reactions of maleimides. Among these, it was discovered that by adding a small amount of a metal-containing compound and a stabilizer to maleamic acid with a concentration of 170-b, side reactions can be significantly suppressed and maleimides with high purity can be produced in high yield and at low cost. This completes the present invention.

That is, the present invention is specified as follows.

(1) When m-ring imidization of maleamic acid is carried out in the presence of an acid catalyst in an organic solvent capable of azeotroping with water, 170 to 25 in the coexistence of at least one metal-containing compound and a stabilizer.
A method for producing maleimides, which comprises carrying out ring-closing imidization while removing produced water as a mixture of the organic solvent from the system at a reaction temperature in the range of 0°C.

(2) The metal-containing compound is at least one selected from the group consisting of oxides, acetates, maleates, halates, nitrates, phosphates, sulfates, and chlorides. The manufacturing method described in (1) above.

(3) The metal-containing compound has a concentration of 0.0% as a metal relative to maleamic acid. 16. The method according to (1) or (2) above, characterized in that OO is used in a range of 5 to 0.5 mol%.

(4) Organic solvent is benzene, toluene, xylene,
Chlorobenzene, ethylbenzene, isopropylbenzene, cumene, mesitylene, tart-butylbenzene,
Pseudocumene, trimedelhexane, octane, tetrachloroethane, nonane, ethylcyclohexane, boiling point 120. ~170°C petroleum fraction, m-dichlorobenzene, 5ec-butylbenzene, p-dichlorobenzene, akan, p-cymene, 0-dichlorobenzene, butylbenzene, decahydronaphthalene, tetrahydronaphthalene, dodecane, (1) above, characterized in that it is at least one member selected from the group consisting of canine phthalin, cyclohexylbenzene, and petroleum distillates with a boiling point of 170 to 250°C;
, (2) or (3).

(5) The acid catalyst is at least one selected from the group consisting of sulfuric acid, sulfuric anhydride, para-toluenesulfonic acid, orthophosphoric acid, metaphosphoric acid, and pyrophosphoric acid, and is 2 to 80 mol% based on the raw material maleamic acid. The method described in (1), (2), (3) or (4) above, characterized in that the method is used within the range of (1), (2), (3) or (4).

(6) The stabilizer is methoxybenzoquinone, P-methoxyphenol, hydroquinone, methylene blue, phenothiazine, tert-butylcatechol, tert
- The group consisting of butylhydroquinone, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper salicylate, thiodipropionic acid esters, mercaptobenzimidazole phosphite, alkylphenols, alkylbisphenols, and alkylated diphenylamines. (1), (2), (3), (4) or (5) above, characterized in that it is at least one type selected from
Manufacturing method described.

The present invention will be explained in more detail below.

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

In particular, the following primary amines are suitable as raw materials for the maleamic acid used in the present invention.

Methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, sec-butylamine, tert-butylamine, n-hexylamine, n-dodecylamine, allylamine, benzylamine, cyclohexylamine, aniline, nitroaniline,
Amine phenol, aminobenzoic acid, anisidine, ethoxyphenylamine, monochloroaniline, dichloroaniline, toluidine, xylidine, ethylaniline, etc.

The synthesis of maleamic acid is carried out almost stoichiometrically, with 0.8 to 1.5 mol of amine per 1.21 mol of maleic anhydride.
It is possible to react mol, preferably 0.9 to 1.2 mol. If the amine compound is in excess of maleic anhydride, it is necessary to use a larger amount of acid catalyst than necessary when directly subjecting it to the imidization reaction, and side reactions may be generated in the imidization reaction. The above range is preferable since a large amount of substances are produced and the yield of the imidization reaction becomes low.

Furthermore, the organic solvent used in the present invention is preferably a solvent that can azeotropically remove the water produced in the dehydration ring-closing reaction, is inert, and does not participate in the reaction, such as benzene, toluene, xylenes, ethylbenzene, isopropylbenzene, cumene, etc. , mesitylene, tert-butylbenzene,
Pseudocumene, trimethylhexane, octane, tetrachloroethane, nonane, chlorobenzene, ethylcyclohexane, petroleum distillate with a boiling point of 120-170°C, m-dichlorobenzene, sec-butylbenzene, p-dichlorobenzene, decane, p- Examples include cymene, 0-dichlorobenzene, butylbenzene, decahydronaphthalene, tetrahydronaphthalene, dodecane, naphthalene, cyclohexylbenzene, and petroleum fractions with a boiling point of 170 to 250°C. The amount of the solvent to be used is 1 to 20 times (by weight), preferably 3 to 7 times the amount of maleamic acid, in order to conduct the reaction smoothly and satisfy economic conditions.

Further, a maleimide having a boiling point suitable for the reaction conditions is selected while taking into consideration the solubility, price, ease of handling, etc. of the maleimide. Furthermore, when considering the separation of the maleimide from the solvent after the reaction is completed, it may be advantageous to use a low boiling point solvent and carry out the reaction under pressure.

As the acid catalyst, sulfuric acid, sulfuric anhydride, pt-toluenesulfonic acid, orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, etc. are used. The amount used is 2 to 80% of maleamic acid.
It is added in an amount of mol %, preferably 10 to 30 mol %.

As a metal-containing compound, at least one metal oxide selected from the group consisting of zinc, chromium, palladium, cobalt, nickel, iron and aluminum, acetate, maleic M salt, succinate, nitrate, phosphoric acid It is selected from salts, chlorides and sulfates, among which vinegar FiI curved lead is particularly effective. The amount of G used in these metals is 0°005 to 0 per mol of maleamic acid.
．． 5 mol%, preferably 0.01 to 0.1 mol%
It is.

As a stabilizer, methoxybenzoquinone, p-methoxyphenol, phenodeazine, alkylated diphenylamines, methylene blue tert-butylcatechol 1, ter't-butylhydroquinone, dimethyldithiocarbamine butyldithia A copper carbamate, copper salicylate, diodibrobionic acid esters , mercaptobenzimidazole, hydroquinone, triphenyl small sulfate, alkylphenols, alkylbisulfonols, etc. are used. The effect of these stabilizers is to allow the maleimide produced by the imidization reaction to exist stably without deterioration even under the high temperature of the imidization reaction υ1
I am accomplishing my goal.

As for the time between additions, it is undesirable to add them slightly, as the effect will be tingling, and on the other hand, adding too much will cause a problem of contamination into the product. Therefore, these machines require O. O O 5-0.
5 mol%, preferably 0.05-0. 3 mol%
It is.

As a method of carrying out the present invention, first, an amine compound is added to a solution of maleic anhydride in an organic solvent, and the temperature is lower than 150°C.
Maleamic acid is obtained by reacting preferably at 30 to 120°C for 15 to 120 minutes. Next, the aforementioned acid catalyst, metal-containing compound, and stabilizer are added without isolating the maleamic acid, and ring-closing imidization is carried out at a reaction temperature of 170 to 250°C. In J3 of the present invention, the reaction rate is increased by carrying out the reaction in the above temperature range, and the selectivity of maleamic acid to maleimides is improved.

The reaction time is usually 1 to 15 hours, and maleimides can be produced in high yield by carrying out the reaction while distilling the produced water out of the system by azeotropic distillation.

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

(1) The selectivity of the imidization reaction is high, and the maleimide produced is stable, so maleimide can be produced in high yield.

(2) It is an extremely safe and inexpensive method since no toxic and expensive solvents are used during maleimide production.

(3) Purification is easy because there are few impurities contained in the generated maleimide! Ji, and a highly pure maleimide compound can be easily obtained.

(4) It is easy to remove the solvent from the product and therefore it has high purity. Maleimide compounds can be obtained.

The present invention will be explained in more detail below using examples.

Example 1 Anhydrous maleic 815 9 and butylbenzene 3 ( A mixed solution of 1!? - A slurry-like liquid containing white crystals of phenylmaleamic acid was obtained.

Next, Ortholin FA 3. 2 Kg, zinc acetate 9
, 69, Phenodeazine 2 6. 7a was added.

Raise the katama to 185°C using a heating jacket.
The reaction was carried out at this temperature for 6 hours. The water produced during this time was distilled off together with butylbenzene.

Thereafter, the temperature was cooled to 30°C, 301 of water was added, and the mixture was stirred for 1 hour. Next, the mixture was allowed to stand for 30 minutes to separate an organic layer and an aqueous layer, and then the aqueous layer was separated and removed. After repeating this operation twice, 30 utts l-1(:J (a
When butylbenzene was removed under reduced pressure in bs), 24
．． Crystals of 7 Ky N-7 enylmaleimide were obtained. The purity of this crystal was 90.8% as determined by liquid chromatography.

Moreover, the yield of this crystal is 89.3 based on the raw material aniline.
Corresponds to mol%.

Example 2 Thermometer, stirrer and 1 liter of water in 11 glass flasks
I installed a vi device.

Next, anhydrous maleic III powder 539 was added to P-cymene 50
The solution dissolved in g was charged into the above flask. Next, the temperature inside the flask was adjusted to 130° C., and a solution in which 50 q of aniline was dissolved in 40 liters of P-cymene was added little by little over 30 minutes to synthesize a slurry liquid of N-phenylmaleamic acid.

To the slurry liquid thus obtained, 10 g of orthophosphoric acid,
Zinc acetate 0.034 g, P-methoxyphenol 0.
O65a was added and reacted at a temperature of 180° C. for 3 hours. It was then cooled to 30°C, washed with water, P-cymene was distilled off under reduced pressure, and N-phenylmaleimide crystals 9
0.5 g was obtained.

The purity of this crystal was measured by liquid chromatography and was 91.5[i%], and the yield of this crystal was 89.
．． Corresponds to 0 mole % to amine.

Examples 3 to 5 The operation was carried out under the same conditions as in Example 2 except that the type of solvent and the degree of reaction were changed, and the following results were obtained.

Example 6 In a flask equipped with the same equipment as in Example 1, a boiling point of 190
100g of a solvent containing 98% or more of an aromatic fraction with a temperature range of ~220°C is charged, and anhydrous maleic M is added to the solvent.
100q was added to raise the temperature inside the flask to 70°C to dissolve maleic anhydride.

Then, 0-chloroaniline 124Q was added to the above solution W870a.
Add the entire solution dissolved in O-
A slurry liquid of chlorophenylmaleamic acid was synthesized.

Next, 10Q of orthophosphoric acid (85% aqueous solution), 0.070% of zinc acetate, and 0.59% of tert-butylcatechol were added to the above slurry liquid, and the temperature was maintained at 185°C while stirring with heating. The reaction was allowed to proceed for 1 hour while being removed by azeotropic operation with the solvent. After the reaction was completed, the temperature of the reaction solution was lowered to 100° C., and the catalyst layer separated from the reaction solution as a lower layer was separated and removed.

Subsequently, the temperature of the reaction solution was lowered to 30° C., 200 G of water was added, and the mixture was stirred and washed with water for 15 minutes to separate the aqueous layer. The above-mentioned solvent was distilled off from the obtained organic layer under reduced pressure to obtain 192q of yellow crystals of 0-chlorophenylmaleimide.

The purity of this product was 94.6% by weight, which corresponded to 90.0% by mole based on the raw material amine.

Example 7 Thermometer, moisture l! 100 q of P-cymene was charged into a flask equipped with a cooling tube, a dropping funnel, and a stirrer, and 100 q of maleic anhydride was added thereto to raise the temperature inside the flask to 100° C. to dissolve the maleic anhydride.

Then, 600 g of p-cymene was added with Schiff [l hexylamine 1
A slurry of P-cymene in N-cyclohexylmaleamidic acid was synthesized by adding the entire amount of the solution containing 00q dropwise over 1 hour while stirring.

Next, 180 g of ortholin, 0.1 q of copper dibutyldithiocarbamate, and 0.7 g of zinc acetate were added to the above slurry liquid, and the mixture was heated and kept at 180°C with stirring, so that the water produced by the reaction was distilled out of the system together with P-cymene. While leaving 7
Allowed time to react. After the reaction was completed, the acid catalyst layer was separated and removed from the reaction solution at 180°C.

Subsequently, the temperature of the reaction solution was lowered to 60° C., 100 g of water was added, and the mixture was stirred and washed with water for 30 minutes, and the aqueous layer was separated.

After repeating this operation twice, 10 m from the organic layer
P-cymene was distilled off under reduced pressure of Hg (abs).

Next, 0.3 g of copper dibutyldithiocarbamate was newly added to the flask, and under reduced pressure of 5 m Hg (abs),
N-cyclohexylmaleimide was distilled over 30 minutes while maintaining the internal temperature at 130 to 150°C. As a result, 162q of bright white crystals of N-cyclohexylmaleimide were obtained.

The purity of this product was 99.8% by weight, and the yield was equivalent to 89.5% by mole based on the starting material cyclohexylamine.

Example 8 A 31" glass flask was heated to 81 °C, equipped with a stirrer and a water separator. Maleic anhydride 12
A xylene solution 2409 containing 0g was charged. Next, add a solution of 220Q dodecylamine and 1ssoa of xylene.
Addition was made in portions over 120 minutes at 0°C. Addition completed: 65.4q of orthophosphoric acid (purity 89% by weight), t of dibutyldithiocarbamic acid! 40.7g and zinc acetate 0.1
5 g was added and reacted at 215° C. for 1 hour under a pressure of 4.4 atm. After that, the temperature was cooled to 30℃ and 400111! After washing with water and separating the aqueous layer and xylene layer, the xylene layer was filtered to obtain 284 g of N-dodecylmaleimide. The purity of this product was 92.4tff1%, and the yield was equivalent to 83.3 mol% based on dodecylamine.

Claims (6)

[Claims] (1) At least one selected from the group consisting of zinc, chromium, cobalt, nickel, iron, aluminum and palladium is used for ring-closing imidization of maleamic acid in the presence of an acid catalyst in an organic solvent capable of azeotroping with water. 170-2 in the coexistence of one metal-containing compound and a stabilizer.
A method for producing maleimides, which comprises carrying out ring-closing imidization at a reaction temperature in the range of 50° C. while removing produced water from the system as a mixture of the organic solvent. (2) The metal-containing compound is at least one selected from the group consisting of oxides, acetates, maleates, succinates, nitrates, phosphates, sulfates, and chlorides. A manufacturing method according to claim (1). (3) The production method according to claim (1) or (2), wherein the metal-containing compound is used in an amount of 0.005 to 0.5 mol% as metal based on maleamic acid. . (4) The organic solvent is benzene, toluene, xylene, chlorobenzene, ethylbenzene, isopropylbenzene, cumene, mesitylene, tert-
Butylbenzene, pseudocumene, trimethylhexane, octane, tetrachloroethane, nonane, ethylcyclohexane, petroleum distillate with a boiling point of 120-170°C, m-dichlorobenzene, sec-butylbenzene, p-dichlorobenzene, decane, p- At least one member selected from the group consisting of cymene, O-dichlorobenzene, butylbenzene, decahydronaphthalene, tetrahydronaphthalene, dodecane, naphthalene, cyclohexylbenzene, and petroleum fractions with a boiling point of 170 to 250°C. The manufacturing method according to claim (1), (2) or (3), characterized in that: (5) The acid catalyst is at least one selected from the group consisting of sulfuric acid, sulfuric anhydride, para-toluenesulfonic acid, orthophosphoric acid, metaphosphoric acid, and pyrophosphoric acid, and is 2 to 80 mol% based on the raw material maleamic acid. The manufacturing method according to (1), (2), (3) or (4), characterized in that the method is used within the range of (1), (2), (3) or (4). (6) The stabilizer is methoxybenzoquinone, P-methoxyphenol, hydroquinone, methylene blue, phenothiazine, tert-butylcatechol, tert-butylhydroquinone, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thio Claims (1) characterized by at least one selected from the group consisting of dipropionic acid esters, mercaptobenzimidazole, triphenyl phosphites, alkylphenols, alkylbisphenols, and alkylated diphenylamines. ), (2), (3), (4) or (5
) The manufacturing method described.