JPH083106A - Production of naphthalenedicarboxylic acid and benzonitrile compound - Google Patents

Abstract

PURPOSE:To industrially obtain a naphthalenedicarboxylic acid as well as a benzonitrile compound both in high yield and purity. CONSTITUTION:A reaction vessel is charged with 2,6-naphthalene dinitrile and benzoic acid as raw materials so as to be (1:13.1) in the molar ratio followed by setting the reaction temperature and distilling column temperature at 250 deg.C and 200 deg.C, respectively, and carrying out a reaction at the atmospheric pressure for 4hr. After completing the reaction, the reaction liquor is subjected to suction filtration under heating at 140 deg.C, and the resultant cake is cooled to room temperature and washed with acetone and then dried at room temperature.

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 naphthalenedicarboxylic acids, and more particularly to a method for producing benzonitriles as well as naphthalenedicarboxylic acids. Naphthalene dicarboxylic acids are useful as raw materials for polyesters and liquid crystal polymers, and benzonitriles are useful as raw materials for benzoguanamine, solvents and agricultural chemicals, and as organic synthetic intermediates.

[0002]

2. Description of the Related Art Among naphthalenedicarboxylic acids, 2,6-naphthalenedicarboxylic acid (hereinafter referred to as 2,6-ND)
(Abbreviated as CA) is the most important compound,
The following three methods are known as methods for producing 6-NDCA. Method for liquid phase oxidation of 2,6-dialkylnaphthalene such as 2,6-dimethylnaphthalene and 2,6-diisopropylnaphthalene in acetic acid solvent in the presence of a transition metal and a catalyst such as bromine NDCA Alkali metal salt Henkel rearrangement Method Hydrolyzing 2,6-naphthalenedinitrile

As a method of, cobalt-manganese-
A method for producing 2,6-NDCA using 2,6-dimethylnaphthalene as a raw material using bromine as a catalyst has been reported (see Japanese Patent Publication No. 56-3337). Although the yield of this method is as high as 95%, it uses many highly corrosive substances such as acetic acid and bromine, and thus requires a reaction apparatus made of an expensive material.

On the other hand, there have been reported many methods for producing 2,6-NDCA by liquid phase oxidation using 2,6-diisopropylnaphthalene, which is easier to synthesize than 2,6-dimethylnaphthalene, as a raw material. For example, a method using cobalt-manganese-bromine as a catalyst (JP-A-4-334).
344), a method using cobalt-manganese-bromine-amine as a catalyst (see JP-A-5-9152), and a method using cobalt-cerium-bromine as a catalyst (see JP-B-5-30818). ), Cobalt-
A method using manganese-rare earth metal-bromine as a catalyst (see JP-A-5-140033) and the like. However, in all cases, the yield is in the order of 70% at most, and the produced NDCA contains impurities other than 2,6-NDCA. Therefore, the product is esterified and distilled, or salt is formed before acid precipitation. Purification is required. Further, compared with the method of oxidizing 2,6-dimethylnaphthalene, a large amount of metal is required as a catalyst, and cobalt required as a component of the catalyst is expensive, so it must be recycled and a high recovery rate is required. Therefore, the treatment of the catalyst becomes troublesome. Further, similarly to the manufacturing method using 2,6-dimethylnaphthalene as a raw material, since bromine having high corrosiveness is used, there is a problem in the manufacturing method that requires a reaction device made of an expensive material.

Regarding the method (1), Japanese Patent Publication No. 49-828
There is a method described in the publication. In this method, a mixture of methylnaphthalene isomers is used as a raw material, liquid-phase oxidation is carried out using cobalt-manganese-bromine as a catalyst, and then the obtained crude naphthoic acid is used as an alkali metal salt. Next, a cadmium, zinc, lead or mercury compound is used as a catalyst, and either or both of thermal disproportionation and thermal rearrangement reaction are carried out in the presence of carbon dioxide gas to obtain a 2,6-NDCA dipotassium salt. . And from this potassium salt, 2,6-NDCA
Get. However, this reaction has a long process and high temperature,
Productivity is low because it is a high-pressure slurry reaction. In addition, since it uses a highly toxic catalyst, there are many industrial problems.

[0006] As a method of,
A method for producing an aromatic carboxylic acid by hydrolysis at 0 ° C. has been reported (see JP-A-48-81828). However, when the aromatic nitrile is 2,6-naphthalenedinitrile, the yield is very low at around 50%, and
A large amount of amide is by-produced, and 2,6-NDCA cannot be obtained in high yield and high purity.

On the other hand, it is known that when a nitrile is reacted with a carboxylic acid, a so-called functional group exchange reaction in which a cyano group and a carboxyl group are exchanged may occur. There is no example used, and it is not known whether it can be used.

[0008]

In the conventional method for producing NDCAs, it is difficult to obtain NDCA with high yield and high purity, and there is a great industrial problem. The present invention has been made to solve the drawbacks of the conventional methods, and is a method for industrially producing NDCAs in high yield and high purity, and benzonitriles in high yield and high purity at the same time. It is intended to provide.

[0009]

Means for Solving the Problems The present inventors conducted a functional group exchange reaction using naphthalenedinitriles and benzoic acids as raw materials. When benzoic acids were used in excess, the concentration of naphthalenedinitriles increased. It has been found that NDCA is produced in high yield without using a substance other than a raw material such as a catalyst although the amount is low. This functional group exchange reaction is an equilibrium reaction as shown in the following formula (1).

Embedded image When R is H, the benzoic acid is benzoic acid and R is CH.
_In the case of ₃ , the benzoic acid is toluic acid.

As a result of further investigation, N formed during the reaction
Due to the precipitation of DCA, the equilibrium is biased to the right side in the formula (1), and further the equilibrium is biased to the right side by performing the reaction while distilling the benzonitriles formed during the reaction, resulting in a high yield. It was found that the concentration of the raw material naphthalene dinitriles can be increased while maintaining the rate. As a result, it is possible to apply a functional group exchange reaction using naphthalenedinitriles and benzoic acids as reactants to produce NDCAs and benzonitriles, and to adjust reaction conditions such as reaction temperature and mixing ratio of raw materials. By studying, it was found that NDCAs and benzonitriles can be simultaneously produced in high yield and high purity, and the present invention has been completed.

That is, according to the present invention, naphthalenedinitriles and benzoic acids are mixed at a molar ratio of 1 to 1 of naphthalenedinitriles and 3 or more of benzoic acids to obtain a product having a boiling point not lower than that of benzonitriles. Is a method of simultaneously producing NDCAs and benzonitriles by heating at a temperature up to the boiling point of benzoic acids, which is one of the starting materials, to carry out a functional group exchange reaction for exchanging cyano groups and carboxyl groups. It is preferable to carry out this reaction while distilling out the benzonitriles formed during the functional group exchange reaction.

As the naphthalenedinitriles which are one of the raw materials, specifically, 1,5-naphthalenedinitrile,
2,6-naphthalenedinitrile, 2,7-naphthalenedinitrile, 2,3-naphthalenedinitrile and the like can be mentioned. Of these, 2,6-naphthalenedinitrile is industrially most useful. These naphthalenedinitriles can be synthesized from the corresponding dimethylnaphthalenes by ammoxidation in the presence of a vanadium catalyst. Specific examples of the other raw material, benzoic acids, include benzoic acid and toluic acid.

The mixing molar ratio of benzoic acids to naphthalenedinitriles is 3 or more of naphthalenedinitriles: benzoic acids, preferably 1: 3 to 1:30, more preferably 1: 5 to 1:15. When the molar ratio of benzoic acids is more than 30, no inconvenience occurs in the reaction, but the concentration of naphthalenedinitriles becomes low, resulting in poor productivity. Conversely, the molar ratio is 1: 3
When the concentration is smaller, that is, when the concentration of naphthalene dinitriles is higher than that, the reaction can be performed by prolonging the reaction time, but since the slurry concentration of NDCA produced is high, the reaction liquid becomes viscous and the reaction It will be practically difficult to continue.

The reaction temperature is defined by the benzoic acid used as the raw material. The lower limit of the reaction temperature is equal to or higher than the boiling point of the corresponding nitriles formed, and the upper limit is near the boiling point of the benzoic acid as a raw material. The higher the reaction temperature, the higher the reaction rate and the shorter the reaction time, which is preferable. As the specific reaction temperature, when the benzoic acid is benzoic acid, the boiling point of benzoic acid is 250 ° C, and the boiling point of benzonitrile produced is 190 ° C.
Therefore, the range of 190 to 250 ° C. is preferable. If the temperature is lower than this, not only the reaction rate becomes extremely small, but also because the nitrile produced does not distill, it is difficult to largely bias the equilibrium to the right, which is disadvantageous. When the raw material benzoic acid is toluic acid, the reaction temperature is preferably 218 to 275 ° C. for the same reason.

[0015]

EXAMPLES The reaction methods and reaction results of the examples will be specifically described below, but the present invention is not limited to these examples. First, FIG. 1 shows the reactor used for the experiment in the laboratory. A 50 ml three-necked flask 2 is used as a reaction container, and is heated to a predetermined reaction temperature by a mantle heater 4. A distillation tower 6 is vertically set up at the center opening 2-1 of the three-necked flask 2, and a band heater 8 is wound around the distillation tower 6 to control the temperature of the distillation tower 8. The temperature of the distillation column 6 is adjusted to a temperature at which the produced benzonitriles maintain a gas phase, that is, a boiling point or higher. A distilling pipe 10 is branched and provided at an upper end portion of the distilling tower 6, and a cooling device 12 is provided in the distilling pipe 10 and cooling water is caused to flow through the cooling device 12 to distill the distilling pipe 10. 10 is cooled. A receiver 14 for receiving condensed benzonitriles is connected to the tip of the distillation pipe 10.

The other mouth 2-2 of the flask 2 is closed and a thermometer 16 is inserted. The temperature of the reaction solution 18 is detected by the thermometer 16 and the detected temperature reaches a predetermined reaction temperature. The energization of the mantle heater 4 is adjusted so that Still another one port 2-3 of the flask 2 is for feeding raw materials and is closed during the reaction. A boiling stone 20 is placed in the flask 2 to prevent the reaction solution 18 from bumping. A thermometer 22 for detecting the temperature in the distillation column 6 is provided at the upper end of the distillation column 6.

(Example 1) The flask 2 was charged with 2,6-
Naphthalene dinitrile 2.00 g and benzoic acid 18.00 g
(Mole ratio 1: 13.1), add boiling stones 20,
Set the reaction temperature to 250 ° C and the distillation column temperature to 200 ° C,
The reaction was allowed to proceed for 4 hours under atmospheric pressure. NDCA during the reaction
Was precipitated and benzonitrile was distilled. The raw material benzoic acid also evaporates, but since the distillation column 6 is set at a temperature lower than the boiling point of benzoic acid, it is condensed in the distillation column 6 and the flask 2 is reconstituted.
Return to

After completion of the reaction, the reaction solution was heated at 140 ° C. and filtered by suction. After cooling the filter cake (filtrate) to room temperature,
It was washed with 10 g of acetone and dried overnight at room temperature. As a result of analyzing the dried filter cake by liquid chromatography, it was 2,6-NDCA with a purity of 99.9%, and the yield was 2.38 g (yield 98.2%). The amount of benzonitrile distilled was 2.28 g (yield 98.5%). N
The yield of DCA is calculated as the mol% of NDCA produced relative to the raw material naphthalene dinitrile, and the yield of benzonitrile is 2 moles of benzonitrile produced per mole of raw material naphthalene dinitrile. It is calculated as mol% based on the number of moles of nitrile × 2.

Example 2 4.00 g of 2,6-naphthalenedinitrile and 16.00 g of benzoic acid (molar ratio 1: 5.
8) The reaction was performed in the same manner as in Example 1 except that the reaction time was 6 hours. As a result of treating the reaction solution in the same manner as in Example 1, 4.70 g (yield 96.8%) of 2,6-NDCA having a purity of 99.7% was obtained. The amount of benzonitrile distilled was 4.43 g (yield 95.7%).

(Example 3) 2.00 g of 2,6-naphthalenedinitrile and 17.00 g of p-toluic acid (molar ratio 1:
7.4), the reaction temperature was 275 ° C., the distillation column temperature was 220 ° C., and the reaction time was 5 hours. The reaction solution was filtered by suction with heating at 185 ° C. and dried in the same manner as in Example 1 to give 3.56 g of a filter cake (yield 97.7).
%) Was obtained. As a result of the analysis, 2,6-N with a purity of 99.8%
It was DCA. The amount of p-tolunitrile (p-methylbenzonitrile) distilled out was 3.81 g (yield 99.6%).

Example 4 3.50 g of 2,7-naphthalenedinitrile and 16.50 g of benzoic acid (molar ratio 1: 6.
9), the reaction was performed in the same manner as in Example 1 except that the reaction time was 6 hours. As a result of treating the reaction solution in the same manner as in Example 1, 4.12 g (yield 97.1%) of 2,7-NDCA having a purity of 99.8% was obtained. Benzonitrile distillate amount is 3.90
It was g (yield 96.3%).

Example 5 0.30 g of 2,6-naphthalenedinitrile and 18.00 g of benzoic acid (molar ratio 1:87.
3) The reaction was carried out in the same manner as in Example 1 except that the distillation column 6 was not kept warm and the produced benzonitrile was hardly distilled. As a result of treating the reaction solution in the same manner as in Example 1, 0.36 g of 2,6-NDCA having a purity of 99.9% (yield 9
8.9%). Although benzonitrile produced in this reaction was not distilled, NDCA could be obtained in high yield and high purity by allowing benzoic acid to exist in a large excess in the raw material.

Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 180 ° C. As a result of treating the reaction solution in the same manner as in Example 1, almost no 2,6-NDCA was obtained. In addition, the distillation of benzonitrile was not confirmed.

(Comparative Example 2) 7.50 g of 2,6-naphthalenedinitrile and 12.5 g of benzoic acid (molar ratio 1: 2.9)
The reaction was performed in the same manner as in Example 1 except that Since the reaction solution was extremely viscous and could not be filtered as in Example 1, the reaction solution was analyzed by dissolving it in a large amount of dimethyl sulfoxide. As a result, the conversion of 2,6-naphthalenedinitrile was 100% and the NDCA yield was 59.
It was 0%. The by-product at this time is a reaction intermediate 6
-Cyano-2-naphthalenecarboxylic acid.

(Comparative Example 3) Example 1 except that the distillation column 6 was not kept warm and the produced benzonitrile was hardly distilled.
The reaction was performed in the same manner as in. The reaction mixture was treated in the same manner as in Example 1 and as a result, 2,6-NDCA having a purity of 80.2% was 2.15.
g (yield 71.2%) was obtained. The by-product was 6-cyano-2-naphthalenecarboxylic acid as in Comparative Example 2.
The above examples and comparative examples are summarized in Table 1 below.

[0026]

[Table 1]

[0027]

INDUSTRIAL APPLICABILITY According to the present invention, naphthalene is obtained by using naphthalene dinitriles and benzoic acids as raw materials, and adjusting the molar ratio thereof to control the temperature to carry out a functional group exchange reaction for exchanging a cyano group and a carboxyl group. It has become possible to simultaneously produce dicarboxylic acids and benzonitriles with high yield and high purity.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing a reaction device used in an example.

[Explanation of symbols]

 2 3-neck flask 4 Mantle heater 6 Distillation tower 10 Distillation tube 18 Reaction liquid

Front page continuation (72) Inventor Isamu Maeda 5-8 Nishiomitabicho Suita City Osaka Prefecture Nippon Shokubai Co., Ltd.

Claims (4)

[Claims] 1. Naphthalenedinitriles and benzoic acids are mixed at a molar ratio of 1 or more naphthalenedinitriles with 3 or more benzoic acids at a temperature not lower than the boiling point of one of the products, benzonitriles. , And production of naphthalenedicarboxylic acids and benzonitriles, which is characterized by carrying out a functional group exchange reaction for exchanging a cyano group and a carboxyl group by heating at a temperature up to the boiling point of benzoic acids, which is one of the raw materials. Method. 2. The method for producing naphthalenedicarboxylic acids and benzonitriles according to claim 1, wherein the reaction is carried out while distilling benzonitriles formed during the functional group exchange reaction. 3. The method according to claim 1 or 2, wherein the naphthalenedinitrile as one raw material is 2,6-naphthalenedinitrile and the naphthalenedicarboxylic acid as one product is 2,6-naphthalenedicarboxylic acid. A method for producing the described naphthalenedicarboxylic acids and benzonitriles. 4. The benzoic acid as the other raw material is benzoic acid, the benzonitriles as the other product is benzonitrile, and the reaction temperature is 190 to 250 ° C. A method for producing naphthalenedicarboxylic acids and benzonitriles.