JP2000143639A - Production of dicarboxylic acid derivative and production of polybenzoxazole precursor using the derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for synthesizing a dicarboxylic acid derivative useful as a synthetic raw material for polybenzoxazole precursor in high purity, efficiency and yield and provide a process for synthesizing a high-purity polybenzoxazole precursor by reacting the above dicarboxylic acid derivative with a diamine and blocking the molecular chain terminals of the product. SOLUTION: A dicarboxylic acid derivative of formula is produced by reacting diphenyl ether-4,4'-dicarboxylic acid with 1-hydroxybenzotriazole using dicyclohexylcarbodiimide as a condensation agent and separating the objective derivative from the reaction solution using a substance having OH group. A high-purity polybenzoxazole precursor is synthesized by reacting the dicarboxylic acid derivative produced by the above process with a diamine and blocking the molecular chain terminals with a carboxylic acid derivative.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photosensitive or radiation-sensitive positive photoresist composition, and a polybenzoxazole precursor used in the production of a heat-resistant protective film and a relief structure of the composition. The present invention relates to a production method and a method for producing a raw material for synthesizing the same.

[0002]

2. Description of the Related Art Conventionally, a polyimide resin having excellent heat resistance and excellent electrical and mechanical properties has been used for a surface protective film and an interlayer insulating film of a semiconductor element. There is a demand for remarkable improvement in heat cycle resistance and heat shock resistance due to the increase in size, increase in size, thinner and smaller package, shift to surface mounting by solder reflow, etc., and further high-performance resin is required. It has become On the other hand, a technique for imparting photosensitivity to the polyimide resin itself has recently attracted attention, and examples thereof include a photosensitive polyimide resin represented by the following formula (III).

[0003]

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When this is used, a part of the pattern forming process can be simplified, which has the effect of shortening the process.
Since a solvent such as methyl-2-pyrrolidone is required, there is a problem in safety and handling. Therefore, recently, a positive photosensitive resin that can be developed with an alkaline aqueous solution has been developed. For example, Japanese Patent Publication No. 1-46862 discloses a positive photosensitive resin composed of a polybenzoxazole precursor and a diazoquinone compound. It has high heat resistance, excellent electrical properties and fine workability, and has the potential not only as a wafer coat but also as an interlayer insulating resin. The mechanism of development of the positive photosensitive resin is that the unexposed portion of the diazoquinone compound is insoluble in the aqueous alkali solution, but the exposure causes the diazoquinone compound to undergo a chemical change and become soluble in the aqueous alkaline solution.
By utilizing the difference in solubility between the exposed part and the unexposed part and dissolving and removing the exposed part, it becomes possible to form a coating film pattern of only the unexposed part.

A method for synthesizing a polybenzoxazole precursor, which is a base polymer of the positive photosensitive resin, is disclosed in Polymer Letter., Vol. 2, pp 655-659 (1964). And a diamine are generally reacted. However, with this method,
Since chlorine ions remain in the polymer and corrode circuit metals, it is practically difficult to use it for semiconductors.

Japanese Patent Application Laid-Open No. 9-183846 discloses a method for synthesizing a polybenzoxazole precursor via a dicarboxylic acid derivative obtained by reacting 1-hydroxybenzotriazole with dicarboxylic acid. With this method, the problem of residual chlorine ions as described above does not occur. Further, in the reaction, the selectivity to an amino group is increased, but the reaction to a hydroxyl group is hard to occur, so that there is an advantage that gelation does not occur.

In Japanese Patent Application Laid-Open No. 9-183846,
Although a method for synthesizing the dicarboxylic acid derivative itself is not described, in the field of conventional organic chemistry, it is a general method to use dicyclohexylcarbodiimide as a condensing agent. However, when the dicarboxylic acid derivative synthesized by this reaction is reacted with a diamine to synthesize a polybenzoxazole precursor, the following problems occur. That is, dicyclohexylcarbodiimide is converted into dicyclohexylurea after a dehydration reaction, which often remains in the isolated polymer. The polybenzoxazole precursor is used by dissolving it in a solvent, and when the solution is stored frozen, the remaining dicyclohexylurea precipitates, which causes a problem that it is difficult to form a fine pattern. Therefore, it is essential that dicyclohexylurea be completely removed and a purely isolated dicarboxylic acid derivative be used.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for synthesizing a dicarboxylic acid derivative, which is a raw material for synthesizing a polybenzoxazole precursor, with high purity, high efficiency and high yield, and a method for synthesizing the dicarboxylic acid derivative with a diamine. To provide a method for synthesizing a high-purity polybenzoxazole precursor obtained by blocking the terminal of the molecular chain after the reaction.

[0009]

According to the present invention, diphenyl ether-4,4'-dicarboxylic acid is reacted with 1-hydroxybenzotriazole using dicyclohexylcarbodiimide as a condensing agent and then reacted with a substance containing an OH group. This is a method for producing a dicarboxylic acid derivative represented by the general formula (I) isolated from a solution. A more preferred embodiment is a method for producing a dicarboxylic acid derivative represented by the general formula (I) in which a substance containing an OH group is added to a filtrate except for dicyclohexylurea, precipitated, and isolated. Further, the substance containing an OH group is one kind of substance selected from the group consisting of water, methanol, ethanol, and isopropyl alcohol or a mixture of two or more kinds thereof, and the diphenyl ether-4,4′-dicarboxylic acid This is a method for producing a dicarboxylic acid derivative in which dicyclohexylcarbodiimide is reacted in a range of 1.9 to 2.3 mol per 1 mol.

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In the general formula (II), the molecular chain end of the reaction product of the above dicarboxylic acid derivative and diamine is sealed with a carboxylic acid derivative having an alkenyl group or an alkynyl group. It is a manufacturing method of the polybenzoxazole precursor shown.

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[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, methods for isolating a desired product from a reaction mixture after completion of a reaction include fractional distillation by distillation, recrystallization, separation using a column, and precipitation by using a poor solvent. is there. As a result of studying these isolation methods,
When isolating a reaction product of the general formula (I) consisting of diphenyl ether-4,4'-dicarboxylic acid and 1-hydroxybenzotriazole, a substance containing an OH group is used to precipitate from the reaction solution and to be isolated. The method was found to be the simplest, high purity, high yield.

The substance represented by the general formula (I) is generally called an active ester. For example, a substance containing an OH group having active hydrogen is considered to be easily decomposed, but in the present invention, diphenyl ether-4,4 is used as a dicarboxylic acid. Since 4'-dicarboxylic acid is used, it hardly decomposes. The reason is that the dicarboxylic acid derivative of the general formula (I) comprising diphenyl ether-4,4′-dicarboxylic acid and 1-hydroxybenzotriazole has low reactivity,
This is considered to be due to the fact that it is difficult to be decomposed by a substance containing an OH group for precipitation, and that the substance containing an OH group is the poorest solvent for the dicarboxylic derivative represented by the general formula (I).

In the present invention, in synthesizing the dicarboxylic acid derivative represented by the general formula (I), dicyclohexylcarbodiimide is used as a condensing agent. A method of making an active ester using dicyclohexylcarbodiimide and 1-hydroxybenzotriazole is known,
In the present invention, it is applied to very limited dicarboxylic acids,
Further, in the isolation, a substance containing an OH group, which was originally unusable, is used.

When this method is applied to, for example, isophthalic acid, which is the most common acid, isophthalic acid and 1-hydroxybenzotriazole are condensed with dicyclohexylcarbodiimide to obtain an active ester.
However, when a substance containing an OH group, such as water, is added to isolate it, hydrolysis occurs, and a part of the product is decomposed into isophthalic acid and 1-hydroxybenzotriazole.

In the synthesis of the general formula (I) in the present invention, diphenyl ether-4,4'-dicarboxylic acid and 1-hydroxybenzotriazole are dissolved in a solvent in advance, and dicyclohexylcarbodiimide is dissolved at a low temperature of -5 to 10 ° C. And further stirred at 20 to 80 ° C, preferably at 20 to 50 ° C. After the reaction,
The dicarboxylic acid derivative is isolated from the group-containing substance to obtain the desired substance. As a more preferable procedure, when the precipitated dicyclohexylcarbodiurea is removed by filtration, and the filtrate is treated with a substance containing an OH group, the filtrate is charged into the target precipitate while stirring the substance containing an OH group. There are a method of obtaining a certain dicarboxylic acid derivative, and a method of adding a substance containing an OH group to the filtrate while stirring the filtrate to obtain a dicarboxylic acid derivative as a desired precipitate, the latter being more preferable. In the latter case, the yield is higher because the content of impurities is smaller, and the yield of products using the latter is also better. In this method, a target dicarboxylic acid derivative having the lowest solubility in a substance containing an OH group is deposited first, and impurities such as unreacted dicyclohexylcarbodiimide and dicyclohexylurea are hardly deposited.

The present invention is characterized in that 1.9 to 2.3 moles of dicyclohexylcarbodiimide is reacted with 1 mole of diphenyl ether-4,4'-dicarboxylic acid in the reaction. When the amount of dicyclohexylcarbodiimide is less than 1.9 mol, the yield of the desired dicarboxylic acid derivative is reduced. When the amount exceeds 2.3 mol, unreacted remaining dicyclohexylcarbodiimide increases, and this becomes dicyclohexylurea. It is not preferable because it easily remains as an impurity.

As a substance containing an OH group, water, methanol, ethanol, isopropyl alcohol and the like can be used. They can also be used as a mixture of two or more. Among these, preferred from the viewpoint of yield are liquid compounds containing 50% or more of water, and most preferred is water. Solvents that can be used for the reaction include, but are not particularly limited to, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethylformamide, and the like.

The dicarboxylic acid derivative represented by the general formula (I) synthesized and isolated by the method of the present invention is then reacted with a diamine in a solvent to synthesize a polybenzoxazole precursor. The reaction temperature of the dicarboxylic acid derivative and the diamine is preferably 20 to 150 ° C. Further, before the completion of the reaction, a carboxylic acid derivative such as an acid anhydride is added to block the terminal amine of the precursor. After the completion of the reaction, the reaction solution is cooled to room temperature, and further poured into a suitable precipitant to precipitate a reaction product. The precipitate obtained by filtration is dried to obtain the desired polybenzoxazole precursor represented by the formula (II). Suitable precipitants are water and mixtures of water with alcohols such as ethanol and isopropanol. Solvents that can be used for the reaction include N-methyl-2-pyrrolidone, N, N-dimethylacetamide,
Dimethylformamide can be mentioned, but is not particularly limited thereto.

X in the polybenzoxazole precursor (II) of the present invention is, for example,

[0020]

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However, the present invention is not limited to these. Among them, particularly preferred are:

[0022]

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It is selected more. Z of the formula (II)
Is, for example,

[0024]

Embedded image Etc., but are not limited to these.

Z in the formula (II) is used when high adhesion to a substrate or the like is required, and its use ratio b can be up to 40 mol%. If it exceeds 40 mol%, the solubility of the resin is extremely reduced, and undeveloped portions (scum) are generated, so that pattern processing cannot be performed.

In the present invention, E of the formula (II) is obtained by reacting a dicarboxylic acid derivative of the general formula (I) with a diamine to synthesize a polybenzoxazole precursor, and then converting the terminal amino group to at least an alkenyl group or an alkynyl group. The terminal is sealed with a carboxylic acid derivative having one, for example, an acid anhydride. As the acid anhydride, maleic anhydride, 5-norbornene-2,3-dicarboxylic anhydride and the like are effective, and particularly, 5-norbornene-2,3-dicarboxylic anhydride is effective. In addition, these X, Z, E
In the use of, one kind or a mixture of two or more kinds may be used.

The dicarboxylic acid derivative represented by the general formula (I) of the present invention can be used as a raw material for synthesizing a general polyamide, polyester and the like in addition to synthesizing a polybenzoxazole precursor.

[0028]

The present invention will be described below in detail with reference to examples. << Example 1 >> * Synthesis of dicarboxylic acid derivative Diphenyl ether-4,4'-dicarboxylic acid 258.
2 g (1 mol) and 1-hydroxybenzotriazole 2
70.3 g (2 mol) was dissolved in 1500 g of N-methyl-2-pyrrolidone, and then 412.7 g (2 mol) of dicyclohexylcarbodiimide dissolved in 500 g of N-methyl-2-pyrrolidone was brought to a reaction system temperature of 0 to 0. Add dropwise while cooling to 5 ° C. After the addition, the temperature of the reaction system was returned to room temperature, and the mixture was stirred for 12 hours. After completion of the reaction, the precipitated dicyclohexylcarbodiurea is removed by filtration, and then 2,000 g of pure water is dropped into the filtrate. The precipitate was collected by filtration, washed sufficiently with isopropyl alcohol, and dried in vacuum. Analysis by an infrared absorption spectrum showed that absorption derived from an ester bond was observed at 1780 cm ^-1 , which confirmed that this was the target dicarboxylic acid derivative and was not decomposed. At this time, the yield was as high as 95%.

* Synthesis of polybenzoxazole precursor The obtained dicarboxylic acid derivative (147.7 g, 0.3 mol) was mixed with hexafluoro-2,2-bis (3-amino-4).
-Hydroxyphenyl) propane 120.9 g (0.3
3 mol) was dissolved in 1000 g of N-methyl-2-pyrrolidone. Thereafter, the reaction system was heated to 75 ° C. and reacted for 12 hours. Next, 5-norbornene-2,3-dicarboxylic anhydride 1 dissolved in 50 g of N-methyl-2-pyrrolidone
1.5 g (0.07 mol) was added, and the mixture was further reacted for 12 hours. The reaction mixture was poured into a solution of water / methanol = 3/1, the precipitate was collected, washed sufficiently with pure water, and dried under vacuum to obtain a polybenzoxazole precursor. Next one
When the residual amount of dicyclohexylcarbodiurea was examined by 1 H-NMR, it was as low as 0.2 wt%.

* Evaluation of Presence or Absence of Precipitate 30 g of polybenzoxazole precursor was added to N-methyl-2.
After dissolving in 70 g of pyrrolidone, the solution was filtered through a 0.2 μm filter. It was stored in a freezer at −20 ° C. for one week, but no precipitate or the like was observed.

[0031]

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Example 2 In the synthesis of the dicarboxylic acid derivative of Example 1, 3000 g of a mixed solution of pure water / methanol = 1/1 was used instead of 2000 g of pure water used for the precipitation.
When the product was analyzed using an infrared absorption spectrum, an absorption derived from an ester bond was observed at 1780 cm ⁻¹ , confirming that this was the target substance and was not decomposed. At this time, the yield was as high as 90%. A polybenzoxazole precursor was synthesized in the same manner as in Example 1, and the residual amount of dicyclohexylcarbodiurea was examined by 1 H-NMR. As a result, it was as low as 0.1 wt%. No precipitate or the like was observed in the evaluation of the presence or absence of the precipitate.

Example 3 In the synthesis of the dicarboxylic acid derivative in Example 1, 3000 g of a mixed solution of pure water / ethanol = 1/1 was used instead of 2000 g of pure water used for precipitation.
g, and the product was analyzed. Infrared absorption spectrum showed absorption at 1780 cm ^-1 derived from an ester bond, confirming that this was the desired product and had not been decomposed. At this time, the yield was as high as 86%. A polybenzoxazole precursor was synthesized in the same manner as in Example 1, and the residual amount of dicyclohexylcarbodiurea was examined by 1 H-NMR. As a result, it was very small, 0.2 wt%. No precipitate or the like was observed in the evaluation of the presence or absence of the precipitate.

Example 4 In the synthesis of the dicarboxylic acid derivative of Example 1, dicyclohexylcarbodiimide (474.6 g, 2.3 mol) was reacted with diphenylether-4,4'-dicarboxylic acid, 258.2 g (1 mol). Other than that, the same operation as in Example 1 was performed. When the product was analyzed, an absorption derived from an ester bond was observed at 1780 cm ^-1 in an infrared absorption spectrum, and thus it was confirmed that this was the target substance and was not decomposed. The yield at this time was as high as 97%. A polybenzoxazole precursor was synthesized in the same manner as in Example 1, and 1H-NM was synthesized.
When the residual amount of dicyclohexylcarbodiurea was examined from R, it was as low as 0.4 wt%. No precipitate or the like was observed in the evaluation of the presence or absence of the precipitate.

EXAMPLE 5 In the synthesis of the dicarboxylic acid derivative of Example 1, 255.8 g (1 mol) of diphenyl ether-4,4'-dicarboxylic acid was reacted with 515.8 g (2.5 mol) of dicyclohexylcarbodiimide. Other than that, the same operation as in Example 1 was performed. When the product was analyzed, an absorption derived from an ester bond was observed at 1780 cm ^-1 in an infrared absorption spectrum, and thus it was confirmed that this was the target substance and was not decomposed. At this time, the yield was as high as 98%. A polybenzoxazole precursor was synthesized in the same manner as in Example 1, and 1H-NM was synthesized.
When the residual amount of dicyclohexylcarbodiurea was examined from R, it was 0.7 wt%. No precipitate or the like was observed in the evaluation of the presence or absence of the precipitate.

Example 6 In the synthesis of the dicarboxylic acid derivative of Example 1, 392.0 g (1.9 mol) of dicyclohexylcarbodiimide was reacted with 258.2 g (1 mol) of diphenyl ether-4,4'-dicarboxylic acid. Other than that, the same operation as in Example 1 was performed. When the product was analyzed, an absorption derived from an ester bond was observed at 1780 cm ^-1 in an infrared absorption spectrum, and thus it was confirmed that this was the target substance and was not decomposed. At this time, the yield was as high as 89%. A polybenzoxazole precursor was synthesized in the same manner as in Example 1, and the residual amount of dicyclohexylcarbodiurea was examined by 1 H-NMR.
It was 0.1 wt% or less. No precipitate or the like was observed in the evaluation of the presence or absence of the precipitate.

Example 7 * Synthesis of dicarboxylic acid derivative Diphenyl ether-4,4'-dicarboxylic acid 258.
2 g (1 mol) and 1-hydroxybenzotriazole 2
70.3 g (2 mol) was dissolved in 1500 g of N-methyl-2-pyrrolidone, and then 412.7 g (2 mol) of dicyclohexylcarbodiimide dissolved in 500 g of N-methyl-2-pyrrolidone was brought to a reaction system temperature of 0 to 0. Add dropwise while cooling to 5 ° C. After the addition, the temperature of the reaction system was returned to room temperature, and the mixture was stirred for 12 hours. After completion of the reaction, the precipitated dicyclohexylcarbodiurea was removed by filtration, and the filtrate was then poured into 2000 g of pure water. The precipitate was collected by filtration, washed sufficiently with isopropyl alcohol, and dried in vacuum. When analyzed by infrared absorption spectrum, absorption derived from an ester bond was observed at 1780 cm ^-1 , which confirmed that this was a dicarboxylic acid derivative and was not decomposed. At this time, the yield was 72%.

* Synthesis of polybenzoxazole precursor The obtained dicarboxylic acid derivative (147.7 g, 0.3 mol) was mixed with hexafluoro-2,2-bis (3-amino-4).
-Hydroxyphenyl) propane 120.9 g (0.3
3 mol) was dissolved in 1000 g of N-methyl-2-pyrrolidone. Thereafter, the reaction system was heated to 75 ° C. and reacted for 12 hours. Next, 5-norbornene-2,3-dicarboxylic anhydride 1 dissolved in 50 g of N-methyl-2-pyrrolidone
1.5 g (0.07 mol) was added, and the mixture was further reacted for 12 hours. The reaction mixture was poured into a solution of water / methanol = 3/1, the precipitate was collected, washed sufficiently with pure water, and dried under vacuum to obtain a polybenzoxazole precursor. Next one
When the residual amount of dicyclohexylcarbodiurea was examined by 1 H-NMR, it was found to be 1.1 wt%, which was slightly large.

* Evaluation of Presence or Absence of Precipitate 30 g of polybenzoxazole precursor was added to N-methyl-2
After dissolving in 70 g of pyrrolidone, the solution was filtered through a 0.2 μm filter. As a result of storing it in a freezer at -20 ° C for one week, precipitates and the like were slightly observed.

Comparative Example 1 In the synthesis of the dicarboxylic acid derivative of Example 1, the synthesis was performed using isophthalic acid instead of diphenyl ether-4,4′-dicarboxylic acid. When the obtained precipitate was analyzed, in addition to the peak derived from the ester bond (1780 cm ^-1 ), an absorption (1720 cm ^-1 ) considered to be partially decomposed was observed, and it was confirmed that the mixture was a mixture. At this time, the recovery rate was as low as 62%.

Comparative Example 2 Diphenyl ether-4,
After dissolving 258.2 g (1 mol) of 4'-dicarboxylic acid and 270.3 g (2 mol) of 1-hydroxybenzotriazole in 1500 g of N-methyl-2-pyrrolidone,
412.7 g (2 mol) of dicyclohexylcarbodiimide dissolved in 500 g of N-methyl-2-pyrrolidone was added dropwise while cooling the temperature of the reaction system to 0 to 5 ° C. After the addition, the temperature of the reaction system was returned to room temperature, and the mixture was stirred for 12 hours. After completion of the reaction, the precipitated dicyclohexylcarbodiurea was removed, and hexafluoro-
2,2-bis (3-amino-4-hydroxyphenyl)
402.9 g (1.1 mol) of propane was added, and the reaction was carried out at a temperature of 75 ° C. for 12 hours. Next, 32.8 g (0.2 mol) of 5-norbornene-2,3-dicarboxylic anhydride dissolved in 50 g of N-methyl-2-pyrrolidone was added, and the mixture was further reacted for 12 hours. The reaction mixture was poured into a solution of water / methanol = 3/1, the precipitate was collected, washed sufficiently with pure water, and dried under vacuum to obtain a polybenzoxazole precursor. When the residual amount of dicyclohexylcarbodiurea was examined by 1H-NMR, it was found to be 3.1% by weight.
And it was found to be very much included. Next, the storage stability was evaluated in the same manner as in Example 1. As a result, a precipitate was observed when stored in a freezer at −20 ° C. for one week.

Comparative Example 3 In the synthesis of the dicarboxylic acid derivative of Example 1, when ethyl acetate was used instead of pure water, no precipitate was found and the target product could not be taken out.

Comparative Example 4 In the synthesis of the dicarboxylic acid derivative of Example 1, propylene glycol monomethyl ether acetate was used in place of pure water, but there was no precipitate and the target product could not be taken out.

[0044]

Industrial Applicability According to the present invention, a method for synthesizing a dicarboxylic acid derivative used for synthesizing a polybenzoxazole precursor with high purity, high efficiency and high yield, and a method for synthesizing the dicarboxylic acid derivative synthesized by the synthesis method The obtained highly pure polybenzoxazole precursor can be provided.

Claims (11)

[Claims] 1. A method comprising reacting diphenyl ether-4,4'-dicarboxylic acid with 1-hydroxybenzotriazole using dicyclohexylcarbodiimide as a condensing agent, and then isolating from the reaction solution with a substance containing an OH group. A method for producing a dicarboxylic acid derivative represented by the general formula (I), characterized in that: Embedded image 2. After reacting diphenyl ether-4,4'-dicarboxylic acid with 1-hydroxybenzotriazole using dicyclohexylcarbodiimide as a condensing agent, a substance containing an OH group is added to the filtrate from which dicyclohexylurea has been removed. A method for producing a dicarboxylic acid derivative represented by the general formula (I), comprising: 3. A general formula wherein the substance containing an OH group according to claim 1 or 2 is one kind of substance selected from the group consisting of water, methanol, ethanol and isopropyl alcohol, or a mixture of two or more kinds. A method for producing the dicarboxylic acid derivative represented by (I). 4. A method for producing a dicarboxylic acid derivative represented by the general formula (I), wherein the substance containing an OH group according to claim 1 or 2 is a substance containing 50% or more of water. 5. A method for producing a dicarboxylic acid derivative represented by the general formula (I), wherein the substance containing an OH group according to claim 1, 2, or 3 is water. 6. The general formula according to claim 1, wherein dicyclohexylcarbodiimide is reacted in an amount of 1.9 to 2.3 mol with respect to 1 mol of the diphenyl ether-4,4'-dicarboxylic acid. A method for producing the dicarboxylic acid derivative represented by (I). 7. A reaction product of a dicarboxylic acid derivative and a diamine obtained according to any one of claims 1 to 6, wherein a molecular chain terminal of the reaction product is sealed with a carboxylic acid derivative having an alkenyl group or an alkynyl group. A method for producing a polybenzoxazole precursor represented by the general formula (II). Embedded image 8. A method for producing a polybenzoxazole precursor according to claim 7, wherein X in the general formula (II) has the following structure. Embedded image 9. X of the general formula (II) according to claim 7 or 8
Is a method for producing a polybenzoxazole precursor having the following structure. Embedded image 10. E in the general formula (II) according to claim 7,
A method for producing a polybenzoxazole precursor having the following structure. Embedded image 11. A method for producing a polybenzoxazole precursor according to claim 7, wherein the general formula (II) has the following structure. Embedded image