JP2002322142A - Method for producing aromatic cyano carboxamide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of industrially advantageously producing an aromatic cyanocarboxamide with high selectivity at a high space-time yield by suppressing the formation of the by-product of the aromatic dicarboxamide in the hydration reaction of an aromatic dinitrile. SOLUTION: In the method for producing the aromatic cyanocarboxamide, only one nitrile group in the aromatic dinitrile is hydrated in the solvent of a N,N-dimethylformaldehyde in the presence of a base.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aromatic cyanocarboxylic acid amide by a partial hydration reaction of an aromatic dinitrile. Aromatic cyanocarboxylic acid amide is
It is useful as a raw material for producing pharmaceuticals, agricultural chemicals, highly functional chemicals, etc., or as an intermediate.

[0002]

2. Description of the Related Art Various methods for obtaining an aromatic cyanocarboxylic acid amide by a partial hydration reaction of an aromatic dinitrile have been proposed. For example, JP-A-52-396
JP-A-48-48980 discloses that terephthalonitrile is hydrolyzed in a lower aliphatic alcohol in the presence of a sodium or potassium alkoxide catalyst by adding a stoichiometric amount of water to hydrolyze only one nitrile group to form 4-cyanobenzoic acid. Although methods for producing amides have been disclosed, they have the disadvantage of using expensive catalysts. JP-A-2-108655 discloses a method in which an amide compound and a nitrile compound are contact-reacted in the presence of a platinum or palladium catalyst. Example 2 describes the reaction between terephthalonitrile and acetamide in the presence of a palladium bromide catalyst, but the space-time yield of 4-cyanobenzoamide is very low because the reaction rate is low, There is also a disadvantage that acetonitrile is by-produced.

Japanese Patent Application Laid-Open No. 12-86610 discloses a method in which phthalonitriles are selectively hydrated in an aliphatic alcohol solvent in the presence of a base with only one nitrile group. Usually, in the hydration reaction of phthalonitriles in the presence of a base catalyst, phthalic diamides are sequentially generated via cyanobenzoic amides, but when the conversion of phthalonitriles is increased, phthalic diamides are produced. And the yield of cyanobenzoic acid amides tends to decrease. Japanese Patent Application Laid-Open No. 12-86610 discloses a method in which a phthalonitrile is added to an aqueous solution of a base in an aliphatic alcohol solvent slowly over a period of time to carry out a hydration reaction. Although cyanobenzoic acid amides have been obtained at an extremely high yield, the space-time yield is low due to the long reaction time, and there is room for improvement in productivity.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to suppress the by-product of aromatic dicarboxylic amide in the hydration reaction of aromatic dinitrile, and to produce aromatic cyanocarboxylic amide with high selectivity and high vacuum. An object of the present invention is to provide an industrially advantageous method which can be produced at a time yield.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that, when an aromatic dinitrile is hydrated in an N, N-dimethylformamide solvent in the presence of a base, The present inventors have found that by-products of aromatic dicarboxylic acid amides are suppressed, and aromatic cyanocarboxylic acid amides can be obtained with a high selectivity and a high space-time yield, thereby completing the present invention. That is, the present invention relates to a method for producing an aromatic cyanocarboxylic acid amide, comprising subjecting an aromatic dinitrile to a hydration reaction of only one nitrile group in an N, N-dimethylformamide solvent in the presence of a base. It is.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The aromatic dinitrile used in the present invention is a compound having two nitrile groups on an aromatic ring such as a benzene ring and a naphthalene ring. Specific examples include phthalonitrile, isophthalonitrile, terephthalonitrile, 1,5-dicyanonaphthalene, 1,8-dicyanonaphthalene, and 2,6-dicyanonaphthalene. In addition, in addition to the nitrile group, an alkyl group such as a methyl group and an ethyl group, a halogen group such as chlorine, bromine, and fluorine, an alkoxy group such as a methoxy group and an ethoxy group, and an aromatic group substituted with one or more hydroxyl groups. Compounds can be used. In particular,
Phthalonitrile, isophthalonitrile, and terephthalonitrile, which are useful as raw materials or intermediates for producing pharmaceuticals, agricultural chemicals, and the like, are preferably used.

In the present invention, N, N-dimethylformamide is indispensable as a reaction solvent, whereby by-products of aromatic dicarboxylic acid amide are suppressed. The amount of the N, N-dimethylformamide solvent to be used can be selected in a range where the solution concentration of the aromatic dinitrile is 1 to 50% by weight, preferably 5 to 30% by weight. If the solution concentration of the aromatic dinitrile is higher than this, it is difficult to control the temperature due to the heat of reaction, and it is also difficult to stir because a large amount of the generated aromatic cyanocarboxylic acid amide precipitates. On the other hand, if it is lower than this, a sufficient space-time yield cannot be obtained.

The base used in the present invention is an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, an alkali metal carbonate such as sodium carbonate or potassium carbonate, or an alkaline earth such as calcium hydroxide or barium hydroxide. Metal hydroxides; tetraalkylammonium hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; Among them,
Alkali metal hydroxides and tetraalkylammonium hydroxides are preferred. One or a combination of two or more of these bases can be used, but the use of sodium hydroxide alone is inexpensive and practical. The amount of the base used is in the range of 0.01 to 1 mol, preferably 0.05 to 0.5 mol, per 1 mol of aromatic dinitrile. If the amount of the base is larger than this, the amount of by-produced aromatic dicarboxylic acid amide increases, while if the amount is smaller than this, a sufficient reaction rate cannot be obtained.

The amount of water used is in the range of 0.5 to 30 mol, preferably 1 to 15 mol, per 1 mol of aromatic dinitrile. If the amount of water used is larger than this, the amount of by-produced aromatic dicarboxylic acid amide increases, while if it is smaller than this, the reaction rate decreases, which is not practical.

The reaction temperature is 50 to 150 ° C., preferably 7
The range is 0 to 120 ° C. If the reaction temperature is lower than this, a sufficient reaction rate cannot be obtained. On the other hand, if it is higher than this, the reaction pressure increases to keep water in a liquid phase, so that the equipment cost increases. The reaction time varies depending on the charging conditions and the reaction conditions, and therefore cannot be expressed uniquely, but is usually 20 minutes to 2 hours.

The reaction of the present invention can be carried out in either a batch system or a flow system. For example, as an example of a batch system, an aromatic dinitrile and N, N-dimethylformamide are charged into a reactor, the contents are heated to a reaction temperature, and then an aqueous solution of a base is added at once and reacted for a predetermined time. In the present invention, an aqueous solution of a base may be divided and charged,
In particular, there is no need to add slowly over time.

The reaction product obtained by the method of the present invention contains, in addition to aromatic cyanocarboxylic acid amide, N, N-dimethylformamide, water and base, unreacted aromatic dinitrile, aromatic dicarboxylic acid amide, aromatic Group dicarboxylic acids and the like. Neutralization, filtration, distillation,
The aromatic cyanocarboxylic amide can be separated and recovered by various methods by combining extraction, recrystallization and the like. For example, a mineral acid such as phosphoric acid or sulfuric acid is added to the reaction product to neutralize the base, and the precipitated mineral acid salt is separated by filtration. Alternatively, the base can be separated by treating the reaction solution with a strongly acidic ion exchange resin. On the other hand, the mother liquor is concentrated using a distillation column, an evaporator or the like, and the precipitated crystals are separated by filtration.
From the reaction product solution, aromatic dicarboxylic acid due to solubility,
Since an aromatic dicarboxylic acid amide, an aromatic cyanocarboxylic acid amide and an aromatic dinitrile are deposited in this order, the operation of concentration and filtration and separation of the precipitated crystals may be repeated several times to sequentially separate and recover each component. In this case, since the unreacted aromatic dinitrile is mainly contained in the final mother liquor, it can be recovered and reused. The aromatic cyanocarboxylic acid amide obtained here is, if necessary,
It can be purified by recrystallization using alcohols such as N, N-dimethylformamide, methanol and ethanol, and ethers such as 1,4-dioxane and tetrahydrofuran as a solvent.

[0013]

EXAMPLES The method of the present invention will be described more specifically below with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist.

Example 1 200 ml of internal volume equipped with a reflux condenser, thermometer and stirrer
Was charged with 6.4 g of terephthalonitrile and 80 g of N, N-dimethylformamide in a three-necked flask, and the flask was placed in an oil bath.
The temperature was kept at 5 ° C. Next, 10 ml of an aqueous 0.5 mol / l sodium hydroxide solution was added, and the reaction temperature was set to 95%.
The reaction was carried out at a temperature of 1 hour. After the reaction, the reaction product is cooled,
Composition analysis was performed using a liquid chromatograph. As a result, the reaction rate of terephthalonitrile was 93.8%,
The selectivity for 4-cyanobenzoic acid amide was 91.6%. In addition, terephthalic acid diamide, terephthalic acid, and the like were by-produced.

Example 2 As in Example 1, 6.4 g of terephthalonitrile, N,
80 g of N-dimethylformamide and 7.5 g of water were charged into a reactor, and while maintaining the reaction temperature in the flask at 95 ° C., 2.5 ml of a 1 mol / liter sodium hydroxide aqueous solution was added. 30 minutes after the start of the reaction, 2.5 ml of a 1 mol / l sodium hydroxide aqueous solution was further added, and the mixture was reacted for 30 minutes. As a result, the conversion of terephthalonitrile was 96.3%, and the selectivity for 4-cyanobenzoamide was 89.0%.

Example 3 3.2 g of terephthalonitrile, 40 g of N, N-dimethylformamide and 5 ml of a 1 mol / l aqueous sodium hydroxide solution were charged into a 100 ml internal volume shaking autoclave (SUS-304) and sealed. . next,
After filling the autoclave with nitrogen gas at 1 MPa, the autoclave was heated to a reaction temperature of 110 ° C. and reacted for 1 hour. After the reaction, the autoclave was cooled, and the composition of the reaction product was analyzed by liquid chromatography. As a result, the conversion of terephthalonitrile was 98.2%, and the selectivity for 4-cyanobenzoamide was 83.2%.

Example 4 As in Example 1, 6.4 g of terephthalonitrile, N,
80 g of N-dimethylformide and 10 g of water were charged into a flask, and heated and maintained at a reaction temperature of 95 ° C. next,
After adding 1.5 ml of a 20% by weight aqueous solution of tetramethylammonium hydroxide, the mixture was reacted for 1 hour. As a result, the conversion of terephthalonitrile was 88.9%,
The selectivity for 4-cyanobenzoic acid amide was 92.4%.

Example 5 A reaction was carried out under the same conditions as in Example 1 except that isophthalonitrile was used instead of terephthalonitrile as a raw material. As a result, the conversion of isophthalonitrile was 96.7%, and the selectivity for 3-cyanobenzoamide was 88.1%. In addition, isophthalic acid diamide, isophthalic acid, and the like were by-produced.

Example 6 Using the reaction product solution obtained in Example 1, 4-cyanobenzoamide was separated and recovered by the following method. Phosphoric acid was added dropwise to the reaction product to neutralize it, and the precipitated sodium phosphate was filtered. On the other hand, in the filtrate, water and N, N-dimethylformamide were completely distilled using a rotary evaporator. Next, 260 g of methanol was added to 12 g of the crystals.
And heated under reflux, and the insolubles were filtered while hot. On the other hand, 147 g of methanol was distilled off from the filtrate using a rotary evaporator, and then cooled, and the precipitated crystals were filtered. This was vacuum dried to obtain 8.9 g of crystals. As a result of composition analysis of the crystals by liquid chromatography, a purity of 9
8.1% of 4-cyanobenzoic acid amide.

[0020]

According to the present invention, in the hydration reaction of aromatic dinitrile, by-products of aromatic dicarboxylic acid amide are suppressed, and aromatic cyanocarboxylic acid amide is obtained with high selectivity and high yield. Therefore, its industrial significance is great.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4H006 AA02 AC53 BA02 BA29 BA69 BB20 BC10 BC31 BC34 QN30 4H039 CA71 CE20

Claims (4)

[Claims] 1. An aromatic dinitrile is reacted with N, N in the presence of a base.
-A method for producing an aromatic cyanocarboxylic acid amide, comprising subjecting only one nitrile group to a hydration reaction in a dimethylformamide solvent. 2. The method according to claim 1, wherein the aromatic dinitrile is phthalonitrile, isophthalonitrile or terephthalonitrile. 3. The base according to claim 1, wherein the base is one or more bases selected from alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides and tetraalkylammonium hydroxides. 3. The method for producing an aromatic cyanocarboxylic acid amide according to 2. 4. The amount of the base is in the range of 0.01 to 1 mol per 1 mol of aromatic dinitrile, and the amount of water is 0.5 to 1 mol.
The method for producing an aromatic cyanocarboxylic acid amide according to any one of claims 1 to 3, which is in a range of from 30 to 30 mol.