JPH09110785A - Production of phthalic acid derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To industrially obtain in high purity and yield a phthalic acid derivative useful as an intermediate for polyimides, by heating a specific phthalonitrile derivative under an acidic condition to form a reaction product which is then dissolved in a specific medium and separated, and by heating the product in an acidic medium and then separating the product. SOLUTION: First, a compound of formula I (X is a halogen) such as 1,4-bis(3,4-dicyanotrifluorophenoxy)tetrafluorobenzene is heated in an acidic aqueous medium to form a product containing a compound A of formula II such as 1,4-bis(3,4-dicarboxytrifluorophenoxy)tetrafluorobenzene. Subsequently, the product is once dissolved in an medium containing an organic solvent (e.g. containing at least 50wt.% of a ketone) and then separated, and the product is, in turn, heated in an acidic aqueous medium; the above process is repeated, and, finally, the product containing the compound A is separated from the acidic medium.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the following general formula (II)
The present invention relates to a method for producing a phthalic acid derivative represented by

The phthalic acid derivative according to the present invention is useful as an intermediate raw material for optical materials, wiring board materials, photosensitive materials, liquid crystal materials and the like. In particular, it is useful as an intermediate of polyimide used as an optical material or a wiring board material.

[0003]

2. Description of the Related Art Conventionally, as a phthalic acid derivative, for example, a method for producing 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene is disclosed in JP-A-5-1148. A method of reacting bis (3,4-dicyanotrifluorophenoxy) tetrafluorobenzene in a 60% sulfuric acid aqueous solution at 150 ° C. for 15 hours is disclosed. However, as can be seen from Reference Example 1 described below, this method has a problem that the purity is less than 95%, which is a practical material.

[0004]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a method for producing a phthalic acid derivative industrially and capable of obtaining a highly pure phthalic acid derivative with a high yield. is there.

[0005]

Means for Solving the Problems The inventors of the present invention have earnestly studied a method for producing a phthalic acid derivative obtained by a hydrolysis reaction of a phthalonitrile derivative represented by the following general formula (I). The cause of the decrease in the purity of the derivative was identified, a countermeasure against the problem was found, and the present invention was completed.

First, in order to find out what is causing the decrease in purity, the hydrolysis reaction in an aqueous sulfuric acid solution was analyzed. As a result, it was found that a phthalamide derivative, which is a reaction intermediate in the hydrolysis of the phthalonitrile derivative, remained in the product considerably. The reason why the reaction intermediate such as a phthalamide derivative remains will be described. First, the reaction form of the hydrolysis reaction is as follows: Heating the sulfuric acid aqueous solution in which the phthalinitrile derivative is dispersed as a solid,
The phthalonitrile derivative gradually melts, and the reaction proceeds in a two-phase state of an organic phase and an aqueous phase. Thereafter, as the reaction progresses, a phthalamide derivative as a reaction intermediate or a target phthalic acid derivative is deposited. At that time, the phthalamide derivative or the like that is in contact with the aqueous solution is further reacted and becomes the target phthalic acid derivative, but the phthalamide derivative that is taken inside the phthalic acid derivative and is not in contact with the aqueous solution is further reacted. It will not progress. As a result, the purity of the phthalic acid derivative was reduced.

Therefore, the inventors of the present invention, as a method for producing the same, by once dissolving the product and then depositing and taking it out,
As a result of investigating improving the purity by precipitating the phthalamide derivative taken in on the solid surface and then further hydrolyzing it to obtain a phthalic acid derivative, the following production method was completed.

That is, the object of the present invention is (1)
(A) A compound represented by the following general formula (I) is heated in an acidic aqueous medium to obtain a product containing the compound represented by the following general formula (II), and (b) the obtained product. Is once dissolved in a medium containing an organic solvent, (c) the product is separated from the medium, (d) the product obtained is heated in an acidic aqueous medium, and (e) after that, In the step of separating the product from the obtained acidic aqueous medium, after performing the steps (a) to (d), the steps (b) to (d) are repeated at least once or more, Finally (e)
Is carried out to obtain a product containing a phthalic acid derivative represented by the following general formula (II).

[0009]

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[0010]

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Another object of the present invention is (2) wherein the compound of the general formula (I) is 1,4-bis (3,4-dicyanotrifluorophenoxy) tetrafluorobenzene, It is also achieved by the production method described in (1) above, wherein the compound (II) is 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene.

Further, another object of the present invention is (3), wherein the medium containing the organic solvent in the step (b) contains at least 50% by weight or more of ketones. ) Or (2).

[0013]

DETAILED DESCRIPTION OF THE INVENTION Each step of the present invention will be described in detail.

(1) Step (a) In this step, the phthalonitrile derivative represented by the above general formula (I) (hereinafter, also simply referred to as phthalonitrile derivative).
Is hydrolyzed under acidic conditions to give a phthalic acid derivative represented by the above general formula (II) (hereinafter also simply referred to as a phthalic acid derivative)
Is a step of obtaining a product containing

In this step, the reaction is usually carried out so as to obtain a product containing 80% or more phthalic acid derivative, but preferably the reaction is carried out so as to obtain a product containing 87% or more phthalic acid derivative. .

The reaction may be carried out by adding the phthalonitrile derivative and the acidic aqueous medium together at the start of the reaction, and then performing the reaction for a predetermined period of time, or dividing the phthalonitrile derivative into the acidic aqueous medium several times during the reaction. Then you can throw it in. As the charging method in the case of dividing and charging, the powder may be used as it is, or may be dissolved in a solvent such as acetic anhydride, propionic anhydride, or acetonitrile, for example.

As the acidic aqueous medium used in this step,
For example, it is preferable to carry out the reaction using an aqueous solution of an inorganic acid such as an aqueous solution of phosphoric acid, an aqueous solution of sulfuric acid, an aqueous solution of hydrochloric acid, and an aqueous solution of sulfuric acid is particularly preferred. By using the sulfuric acid aqueous solution, the target product can be efficiently obtained in a high yield.

For example, the case of using a sulfuric acid aqueous solution for the reaction will be described in detail.

First, the concentration of sulfuric acid in this step is 40
It is preferable to use an aqueous solution of sulfuric acid in the range of to 85% by weight, and particularly preferable to use an aqueous solution of sulfuric acid in the range of 50 to 80% by weight. When the concentration of sulfuric acid is high, the reaction intermediate such as amide or anhydride of phthalic acid derivative is likely to be produced and the purity is lowered, and it is difficult to remove the sulfuric acid after the reaction. On the other hand, if it is low, the reaction temperature cannot be raised sufficiently and the reaction rate decreases, resulting in poor productivity.

In this step, the concentration of the phthalonitrile derivative in the aqueous sulfuric acid solution is preferably in the range of 5 to 50% by weight. When the concentration is high, it becomes difficult to control the reaction, and when the concentration is low, productivity is deteriorated, which is not preferable.

The reaction temperature in this step is 120.
It is preferable to carry out in the range of ~ 180 ° C, especially 140 ~
It is preferably carried out in the range of 170 ° C. When the reaction temperature is high, it becomes difficult to control the reaction, and when the reaction temperature is low, the reaction rate decreases and the productivity deteriorates, which is not preferable.

The reaction time in this step depends on the reaction temperature and the like, but can be usually 1 to 24 hours.

After completion of the reaction, the phthalic acid derivative as a product is precipitated in the reaction solution. When using in the next step (b), the reaction solution may be used as it is or may be filtered to use only the filtered material. May be.

Regarding Steps (b) and (c) In these steps, the product obtained in the previous step (a) or the reaction solution obtained in the step (d) is once added to a medium containing an organic solvent. By dissolving (step (b)) and separating the product from the medium (step (c)), the phthalamide derivative and the like incorporated inside the phthalic acid derivative are exposed on the solid surface.

In this step, the method is as follows:
There is a method in which water and an organic solvent having a two-layered state are directly added to the reaction solution of (3) to dissolve the product (step (b)), and then the organic layer is separated and evaporated to dryness (step (c)).

The organic solvent to be added is not particularly limited as long as it has a two-layer state with water and does not react with the product, but fatty acid esters, ketones, ethers and benzonitriles are preferable. Especially, fatty acid esters and ketones are preferable. Examples thereof include ethyl acetate, isopropyl acetate, methyl isobutyl ketone and the like. There is no problem with the amount of the organic solvent used as long as it can dissolve the product. After that, the organic layer may be separated from the medium, and the organic layer may be washed with water if necessary. Then, it is evaporated to dryness to obtain a product, which is used in the next step (d).

In the present steps (b) and (c), as another method, the reaction solution of the step (a) is once filtered, and a medium containing an organic solvent is added to and dissolved in the filtrate (step (B)), if the organic solvent added thereafter is in a two-layer state with water, liquid separation is performed, and the product is obtained by evaporating the organic layer to dryness, and the added organic solvent is in a two-layer state with water. If it does not become, the product can be obtained by adding water thereafter until a solid is precipitated and then filtering and drying (step (c)).

When an organic solvent having a two-layer state with water is used, the organic solvent to be added is not particularly limited as long as it does not react with the product, but fatty acid esters, ketones, ethers, benzo Nitriles are preferable, and fatty acid esters and ketones are particularly preferable. Examples thereof include ethyl acetate, isopropyl acetate, methyl isobutyl ketone and the like. There is no problem as long as the amount of the organic solvent used is at least an amount capable of dissolving the product. afterwards,
The organic layer may be separated, and if necessary, the organic layer may be washed with water. Then, the organic layer is evaporated to dryness to obtain a product, which is used in the next step (d).

When using a material that does not form a two-layer state with water,
The organic solvent to be added is not particularly limited as long as it does not react with the product, but ketones, acetonitriles and alcohols are preferable, and ketones are particularly preferable. For example, acetone, acetonitrile, methanol, ethanol and the like can be mentioned. There is no problem with the amount of the organic solvent used as long as it can dissolve the product.
Then, water is added until a solid precipitates, and the product is obtained by filtration and drying and used in the next step (d).

There is no problem as long as the amount of water is added in such an amount that solids are deposited. For example, when the organic solvent is acetone, water may be used in an amount 5 times or more by weight.

(3) Step (d) This step is a step of further hydrolyzing the product obtained in step (c).

The reaction may be carried out by adding the product obtained in step (c) and the acidic aqueous medium together at the start of the reaction, and then performing the reaction for a predetermined time. Alternatively, the reaction may be performed in the acidic aqueous medium in the reactor. The product obtained in step (c) may be divided and added several times. As a charging method in the case of dividing and charging, the powder may be used as it is, or may be dissolved in a solvent such as acetic anhydride, propionic anhydride, or acetonitrile, for example.

As the acidic aqueous medium used in this step,
The reaction is preferably carried out using an aqueous solution of an inorganic acid such as an aqueous solution of phosphoric acid, an aqueous solution of sulfuric acid, an aqueous solution of hydrochloric acid, and an aqueous solution of sulfuric acid is particularly preferred. By using the sulfuric acid aqueous solution, the target product can be efficiently obtained in a high yield.

For example, the case of using a sulfuric acid aqueous solution for the reaction will be described in detail.

First, the concentration of sulfuric acid in this step is 40
It is preferable to use an aqueous solution of sulfuric acid in the range of to 85% by weight, and particularly preferable to use an aqueous solution of sulfuric acid in the range of 50 to 80% by weight. When the concentration of sulfuric acid is high, the reaction intermediate such as amide or anhydride of phthalic acid derivative is likely to be produced and the purity is lowered, and it is difficult to remove the sulfuric acid after the reaction. On the other hand, if it is low, the reaction temperature cannot be raised sufficiently and the reaction rate decreases, resulting in poor productivity.

In this step, the concentration of the product obtained in the previous step (c) in the aqueous sulfuric acid solution is preferably in the range of 5 to 50% by weight. When the concentration is high, it becomes difficult to control the reaction, and when the concentration is low, productivity is deteriorated, which is not preferable.

The reaction temperature in this step is 120.
It is preferable to carry out in the range of ~ 180 ° C, especially 140 ~
It is preferably carried out in the range of 170 ° C. When the reaction temperature is high, it becomes difficult to control the reaction, and when the reaction temperature is low, the reaction rate decreases and the productivity deteriorates, which is not preferable.

The reaction time in this step depends on the reaction temperature and the like, but can usually be 1 to 24 hours.

After completion of the reaction, depending on the target purity of the target phthalic acid derivative, the above-mentioned (b) to (d) are repeated a predetermined number of times.
The above step is repeated, and the final step (e) is performed.

(4) Step (e) This step is a step of separating the product obtained in step (d) from the reaction solution (acidic aqueous medium).

In this step, the method is as follows:
There is a method in which water and an organic solvent having a two-layered state are directly added to the reaction solution to dissolve it, and then the organic layer is separated and evaporated to dryness.
The organic solvent to be added is not particularly limited as long as it is in a two-layer state with water and does not react with the product, but fatty acid esters, ketones, ethers and benzonitriles are preferable, and fatty acid is particularly preferable. Esters and ketones are preferable. Examples thereof include ethyl acetate, isopropyl acetate, methyl isobutyl ketone and the like. There is no problem with the amount of the organic solvent used as long as it can dissolve the product. After that, the organic layer may be separated, and if necessary, the organic layer may be washed with water. Then, it is evaporated to dryness to obtain the product.

In this step, as another method, the reaction solution of step (d) is once filtered, and a solvent containing an organic solvent is added to the filtered solution to dissolve the filtered solution. If it is in a two-layer state with a layer, liquid separation is performed, the organic layer is evaporated to dryness to obtain a product, and if the added organic solvent is not in a two-layer state with water, a solid of water is precipitated. Then, the product can be obtained by filtration and drying. When an organic solvent that forms a two-layer state with water is used, the organic solvent to be added is not particularly limited as long as it does not react with the product, but fatty acid esters, ketones,
Ethers and benzonitriles are preferable, and fatty acid esters and ketones are particularly preferable. Examples thereof include ethyl acetate, isopropyl acetate, methyl isobutyl ketone and the like. There is no problem with the amount of the organic solvent used as long as it can dissolve the product. After that, the organic layer may be separated, and if necessary, the organic layer may be washed with water. Then, it is evaporated to dryness to obtain the product. When a solvent that does not form a two-layer state with water is used, the organic solvent to be added is not particularly limited as long as it does not react with the product, but ketones, acetonitriles, alcohols are preferable, and ketones are particularly preferable. Is preferred. For example, acetone, acetonitrile, methanol, ethanol and the like can be mentioned. There is no problem with the amount of the organic solvent used as long as it can dissolve the product. Then, water is added until a solid precipitates, and the product is obtained by filtration and drying. There is no problem if the amount of water is added in an amount not less than the amount by which solids are precipitated. For example, when the solvent is acetone, water by weight of 5 times or more may be used.

By performing the above steps, it becomes possible to obtain a high-purity phthalic acid derivative in a high yield.

[0044]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 (1) 20 equipped with a stirrer, a cooling reflux tube and a thermometer
1,4-bis (3,4-dicyanotrifluorophenoxy) tetrafluorobenzene 1 in a 0 ml three-necked flask.
0 g and 90 g of a 70 wt% sulfuric acid aqueous solution were added, and the reaction was carried out at the reflux temperature for 6 hours. After completion of the reaction, the mixture was cooled to room temperature, 200 ml of water was added and filtered, and the filtrate was washed twice with 10 ml of water. Remove the soot into a 100 ml beaker,
8 ml of acetone was added and dissolved. 80 ml of water was added to precipitate a solid, and the precipitated solid was filtered and dried to obtain a product 1
0.8 g was obtained. Analysis by liquid chromatography revealed that 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene was 91.
It was found to contain 8%.

(2) In a 200 ml three-necked flask equipped with a stirrer, a cooling reflux tube and a thermometer, the above product (1,
4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene 91.8% content) 10.8
g and 90 g of a 70 wt% sulfuric acid aqueous solution were added, and the reaction was carried out at the reflux temperature for 6 hours. After the reaction was completed, the mixture was cooled to room temperature, 200 ml of water was added, and the mixture was filtered.
Washed twice. The filtrate was taken out in a 100 ml beaker, and 8 ml of acetone was added and dissolved. 80 ml of water was added to precipitate a solid, and the precipitated solid was filtered and dried to obtain the product 10.
3 g were obtained. When analyzed by liquid chromatography, 96.4% of 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene was obtained.
It was found to contain.

(3) In a 200 ml three-necked flask equipped with a stirrer, a cooling reflux tube and a thermometer, the above product (1,
4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene 96.4% content) 10.3
g and 90 g of a 70 wt% sulfuric acid aqueous solution were added, and the reaction was carried out at the reflux temperature for 6 hours. After the reaction was completed, the mixture was cooled to room temperature, 200 ml of water was added, and the mixture was filtered.
Washed twice. The filtrate was taken out in a 100 ml beaker, and 8 ml of acetone was added and dissolved. 80 ml of water was added to precipitate a solid, and the precipitated solid was filtered and dried to obtain a product 9.8.
g was obtained. Analysis by liquid chromatography revealed that it contained 99.2% of 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene.

Example 2 The reaction was carried out in the same manner as in Example 1 except that 90 g of a 50% sulfuric acid aqueous solution was used instead of 90 g of a 70 wt% sulfuric acid aqueous solution, and 1,4-bis (3,4-dicarboxytricarboxylic acid) was used. 9.6 g of fluorophenoxy) tetrafluorobenzene was obtained. When analyzed by liquid chromatography, the purity was 99.1%.

Example 3 The reaction was carried out in the same manner as in Example 1 except that 90 g of 80% sulfuric acid aqueous solution was used instead of 90 g of 70% by weight sulfuric acid aqueous solution, and 1,4-bis (3,4-dicarboxytricarboxylic acid) was used. 9.8 g of fluorophenoxy) tetrafluorobenzene was obtained. When analyzed by liquid chromatography, the purity was 99.0%.

Example 4 (1) 20 equipped with a stirrer, a cooling reflux tube and a thermometer
90 g of 70 wt% sulfuric acid aqueous solution is added to a 0 ml three-necked flask and heated to reflux temperature. 10 g of 1,4-bis (3,4-dicyanotrifluorophenoxy) tetrafluorobenzene was added thereto over 1 hour, and then,
The reaction was carried out at the reflux temperature for 5 hours. After completion of the reaction, the mixture was cooled to room temperature, 200 ml of water was added, and the mixture was filtered.
Washed twice with ml. The filtrate was taken out in a 100 ml beaker, and 8 ml of acetone was added and dissolved. 80 ml of water was added to precipitate a solid, and the precipitated solid was filtered and dried to obtain 10.7 g of a product. Analysis by liquid chromatography revealed that 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene was found to be 9
It was found to contain 2.1%.

(2) A 200 ml three-necked flask equipped with a stirrer, a cooling reflux tube and a thermometer was charged with the above product (1,
4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene 92.1% content) 10.7
g and 90 g of a 70 wt% sulfuric acid aqueous solution were added, and the reaction was carried out at the reflux temperature for 6 hours. After the reaction was completed, the mixture was cooled to room temperature, 200 ml of water was added, and the mixture was filtered.
Washed twice. The filtrate was taken out in a 100 ml beaker, and 8 ml of acetone was added and dissolved. 80 ml of water was added to precipitate a solid, and the precipitated solid was filtered and dried to obtain the product 10.
4 g were obtained. When analyzed by liquid chromatography, 96.2% of 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene was obtained.
It was found to contain.

(3) In a 200 ml three-necked flask equipped with a stirrer, a cooling reflux tube and a thermometer, the above product (1,
4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene 96.2% content) 10.4
g and 90 g of a 70 wt% sulfuric acid aqueous solution were added, and the reaction was carried out at the reflux temperature for 6 hours. After the reaction was completed, the mixture was cooled to room temperature, 200 ml of water was added, and the mixture was filtered.
Washed twice. The filtrate was taken out in a 100 ml beaker, and 8 ml of acetone was added and dissolved. 80 ml of water was added to precipitate a solid, and the precipitated solid was filtered and dried to obtain a product 9.4.
g was obtained. Analysis by liquid chromatography revealed that it contained 99.1% of 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene.

Example 5 (1) 20 equipped with a stirrer, a cooling reflux tube and a thermometer
1,4-bis (3,4-dicyanotrifluorophenoxy) tetrafluorobenzene 1 in a 0 ml three-necked flask.
0 g and 90 g of a 70 wt% sulfuric acid aqueous solution were added, and the reaction was carried out at the reflux temperature for 6 hours. After completion of the reaction, the mixture was cooled to room temperature, 100 ml of water was added, and methyl isobutyl ketone 2 was added.
Add 00 ml to dissolve the precipitated solid. The organic layer was separated and washed twice with 20 ml of water. The organic layer was evaporated to dryness to obtain 10.9 g of product. Analysis by liquid chromatography revealed that it contained 91.5% of 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene.

(2) A 200 ml three-necked flask equipped with a stirrer, a cooling reflux tube and a thermometer was charged with the above product (1,
4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene 91.5% content) 10.9
g and 90 g of a 70 wt% sulfuric acid aqueous solution were added, and the reaction was carried out at the reflux temperature for 6 hours. After completion of the reaction, the mixture was cooled to room temperature, 100 ml of water was added, and further methyl isobutyl ketone 20
Add 0 ml to dissolve the precipitated solid. The organic layer was separated and washed twice with 20 ml of water. The organic layer was evaporated to dryness to obtain 10.6 g of product. Analysis by liquid chromatography revealed that it contained 95.9% of 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene.

(3) In a 200 ml three-necked flask equipped with a stirrer, a cooling reflux tube and a thermometer, the above product (1,
4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene 95.9% content) 10.6
g and 90 g of a 70 wt% sulfuric acid aqueous solution were added, and the reaction was carried out at the reflux temperature for 6 hours. After completion of the reaction, the mixture was cooled to room temperature, 100 ml of water was added, and further methyl isobutyl ketone 20
Add 0 ml to dissolve the precipitated solid. The organic layer was separated and washed twice with 20 ml of water. The organic layer was evaporated to dryness to give 10.2 g of product. Analysis by liquid chromatography revealed that it contained 99.0% of 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene.

Comparative Example 1 200 ml equipped with a stirrer, a cooling reflux tube and a thermometer
To a three-necked flask, 10 g of 1,4-bis (3,4-dicyanotrifluorophenoxy) tetrafluorobenzene and 90 g of a 70 wt% sulfuric acid aqueous solution were added, and the mixture was refluxed at a temperature of 6
A time reaction was performed. After the reaction is complete, cool to room temperature and add water 20
After adding 0 ml, the precipitated product was filtered and further washed with 10 ml of water twice. Then, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene was dried at 10.6 by drying the filtrate.
g was obtained. The purity of the obtained compound was 91.8% as a result of analysis by liquid chromatography.

Reference Example 1 200 ml equipped with a stirrer, a cooling reflux tube and a thermometer
To a three-necked flask, 10 g of 1,4-bis (3,4-dicyanotrifluorophenoxy) tetrafluorobenzene and 18.5 ml of a 60% by weight sulfuric acid aqueous solution were added, and 150
The reaction was carried out at 150C for 15 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, the precipitated product was filtered, and further washed with water. After that, the 1,4-bis (3,3
10.3 g of 4-dicarboxytrifluorophenoxy) tetrafluorobenzene was obtained. The purity of the obtained compound was 91.8 as a result of analysis by liquid chromatography.
%Met.

Claims (3)

[Claims] (A) A compound represented by the following general formula (I) is heated in an acidic aqueous medium to obtain a product containing the compound represented by the following general formula (II), and (b) then, The obtained product is once dissolved in a medium containing an organic solvent, (c) the product is separated from the medium, and (d) further,
In the step of heating the obtained product in an acidic aqueous medium and (e) then separating the product from the obtained acidic aqueous medium, the steps (a) to (d) above are performed. After that, the steps (b) to (d) are repeated at least once or more, and finally the step (e) is performed to give the following general formula (II).
A process for producing a product containing a phthalic acid derivative represented by: Embedded image Embedded image 2. The compound of general formula (I) is 1,4-
Bis (3,4-dicyanotrifluorophenoxy) tetrafluorobenzene, wherein the compound of the general formula (II) is 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene. 1. The manufacturing method according to 1. 3. The production method according to claim 1, wherein the medium containing the organic solvent in the step (b) contains at least 50% by weight or more of ketones.