Method for producing trimellitic anhydride ester

Abstract

To provide a method for producing a trimellitic anhydride ester satisfying high yield, high purity and low chlorine content required for an electronic material by a simple operation.SOLUTION: The method for producing a trimellitic anhydride ester includes a step A of reacting a trimellitic anhydride halide and a specific alkanediol to obtain a crude trimellitic ester, and a step B of purifying the crude trimellitic ester, wherein the step B includes a step B1 of mixing a poor solvent having an octanol / water partition coefficient of -2.0 or more and 0.0 or less and a boiling point of 40°C or more and 120°C or less with the crude trimellitic ester to reprecipitate the crude trimellitic ester, and a step B2 of heating the mixed liquid containing at least the crude trimellitic ester after the reprecipitation and acetic anhydride, and recrystallizing the trimellitic ester.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing trimellitic anhydride esters. [Background technology]

[0002] Acid dianhydrides are industrially useful chemicals, not only as raw materials for polyimide, a heat-resistant resin, but also as curing agents for epoxy resins and polyurethane resins, and various methods for their production are being investigated. In recent years, polyimides, epoxy resins, and urethane resins have also been used in materials for electronic information devices (also referred to as "electronic materials" in this specification). However, when some acid anhydrides are used as curing agents for electronic materials, the adhesion may be insufficient. Furthermore, electronic materials using some acid anhydrides may exhibit warping. Therefore, trimellitic anhydride esters, which have high flexibility, have attracted attention as acid dianhydrides. Furthermore, as electronic information devices have become smaller in recent years, stricter standards have been applied to the quality of electronic materials. For example, there is a greater demand for improved electrical reliability than before, and there is also a stronger demand for improved product purity and reduced foreign matter.

[0003] Conventionally, a method for preparing trimellitic anhydride esters by reacting trimellitic anhydride halide with alcohols has been reported as a method for producing trimellitic anhydride esters (for example, Patent Document 1). Also disclosed is a method in which trimellitic anhydride halide is reacted with bisphenols, and then nitriles and aromatic hydrocarbons are mixed therewith for purification (for example, Patent Document 2). Furthermore, a method in which trimellitic anhydride halide is reacted with bisphenols, and then water is added and the mixture is washed at 40°C (Patent Document 3) has been disclosed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-213189 [Patent Document 2] Japanese Patent Application Publication No. 2017-203005 [Patent Document 3] Patent Publication No. 2021-161161 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the organic solvent (e.g., methyl ethyl ketone) used in the recrystallization and crystallization steps of the method of Patent Document 1 is highly hydrophobic. Therefore, although the purification conditions in the production method of Patent Document 1 can improve the purity of the trimellitic anhydride ester, there is a problem in that it is difficult to reduce the chlorine content in the trimellitic anhydride ester.

[0006] Furthermore, when the method of Patent Document 2 is applied to a method for producing a trimellitic anhydride ester by reacting trimellitic anhydride with an alkanediol, impurities are likely to be generated if the reaction temperature exceeds 30° C. Furthermore, there is a concern that increasing the number of washing steps to reduce foreign matter, which is required for electronic materials, may result in a decrease in yield.

[0007] Furthermore, when the method of Patent Document 3 is applied to a method for producing a trimellitic anhydride ester by reacting trimellitic anhydride with an alkanediol, the alkanediol has a lower hydrophobicity than bisphenol, and therefore, there is a concern that the purity may decrease due to hydrolysis when washed at 40°C.

[0008] Therefore, it is difficult to produce a high-purity trimellitic anhydride ester by reacting trimellitic anhydride with an alkanediol using any of the methods described in the above-mentioned documents, and it is difficult to meet the increasingly demanding requirements for applications such as electronic materials.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a trimellitic anhydride ester in a high yield by a simple operation, which satisfies the requirements for high purity and low chlorine content for electronic materials and the like. [Means for solving the problem]

[0010] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they have found that the above-mentioned problems can be solved by reprecipitation of a crude trimellitic anhydride ester obtained by reacting a trimellitic anhydride halide with an alkanediol having a specific structure using a specific poor solvent, followed by ring closure and recrystallization steps, thereby completing the present invention.

[0011] The method for producing the trimellitic anhydride ester of the present invention is as follows. 1. A method comprising: Step A of reacting trimellitic anhydride halide with an alkanediol represented by the following general formula (1) to obtain a crude trimellitic anhydride ester containing a trimellitic anhydride ester represented by the following general formula (2); and a step of purifying the crude trimellitic anhydride ester, wherein the step of purifying the crude trimellitic anhydride comprises Step B of mixing the crude trimellitic anhydride ester with a poor solvent having an octanol / water partition coefficient of -2.0 or more and 0.0 or less and a boiling point of 40°C or more and 120°C or less, to reprecipitate the crude trimellitic anhydride; and Step C of heating a mixture obtained by adding acetic anhydride to the crude trimellitic anhydride after precipitation, and then recrystallizing the trimellitic anhydride. [ka] (In general formula (1), R 1 represents a linear alkylene group having 2 to 16 carbon atoms. [ka] (In general formula (2), R 1 represents a linear alkylene group having 2 to 16 carbon atoms. 2. The method for producing a trimellitic anhydride ester according to [1], wherein step B is carried out at a temperature in the range of 0°C or higher and 20°C or lower. [Effects of the Invention]

[0012] According to the production method of the present invention, trimellitic anhydride esters having high purity and low chlorine content can be obtained in high yield through simple operations. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below. The present invention is a method for producing a trimellitic anhydride ester represented by the following general formula (2) by reacting a trimellitic anhydride halide with a specific alkanediol. [ka] In general formula (2), R 1 represents a linear alkylene group having 2 to 16 carbon atoms, and R 1 preferably has 6 to 12 carbon atoms.

[0014] The production method includes a step of reacting trimellitic anhydride halide with a specific alkanediol to obtain crude trimellitic anhydride halide containing a trimellitic anhydride ester represented by the general formula (2), and a step of purifying the crude trimellitic anhydride ester. Each step will be described below.

[0015] [Step A: Reaction of Trimellitic Anhydride Halide with Alkanediol (to Obtain Crude Trimellitic Anhydride Ester)] In this step (hereinafter also referred to as "reaction step A"), trimellitic anhydride halide is reacted with a specific alkanediol. The trimellitic anhydride halide used in this step may be one produced by a known method or may be purchased. In this specification, "trimellitic anhydride halide" may be any halogenated derivative of trimellitic anhydride. Examples of the trimellitic anhydride halide include trimellitic anhydride chloride, trimellitic anhydride bromide, trimellitic anhydride iodide, and trimellitic anhydride fluoride. Among these trimellitic anhydride halides, trimellitic anhydride chloride is preferably used because it is inexpensive and easily available.

[0016] On the other hand, alkanediol is a compound represented by the following general formula (1). [ka] In the above general formula (1), R 1 represents a linear alkylene group having 2 to 16 carbon atoms. R in the above general formula (1) 1 If the carbon number of R is 17 or more, there is a problem with market circulation, and the reactivity decreases, which may cause a decrease in purity. 1 When the carbon number of R is 1, i.e., methanediol, the reactivity is reduced due to the steric hindrance of the trimellitic anhydride halide. 1 However, when the carbon number is 2 or more and 16 or less, the reactivity with trimellitic anhydride halide is good, and it is easy to obtain a trimellitic anhydride ester with high purity. 1 More preferably, the number of carbon atoms is 6 or more and 12 or less.

[0017] Examples of the alkanediol represented by the general formula (1) include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, etc. Among these, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, etc. are preferred.

[0018] When reacting the alkanediol with trimellitic anhydride halide, the ratio of these amounts should be 1 molar equivalent of trimellitic anhydride per mole of hydroxyl groups in the alkanediol. However, to complete the reaction, trimellitic anhydride halide can be used in excess relative to the amount of hydroxyl groups in the alkanediol. The amount of trimellitic anhydride used can be, for example, 1.0 to 1.5 molar equivalents per mole of hydroxyl groups in the alkanediol, with 1.0 to 1.2 molar equivalents being more preferred. Insufficient amounts of trimellitic anhydride halide relative to the amount of hydroxyl groups in the alkanediol can undesirably cause a reaction between the hydroxyl groups and the acid anhydride moiety, potentially generating by-products. In contrast, using an amount of 1.0 to 1.5 molar equivalents per mole of hydroxyl groups in the alkanediol can suppress the generation of by-products and ensure efficient reaction.

[0019] In this reaction, hydrogen chloride is produced as a by-product as the reaction proceeds. To neutralize this hydrogen chloride, the reaction may be carried out using a neutralizing agent such as a base. Examples of bases that can be used as neutralizing agents include inorganic bases such as sodium hydroxide and sodium carbonate; basic ion exchange resins; organic tertiary amines such as triethylamine and tributylamine; and aromatic amines such as pyridine. Among these, amines are preferred, with pyridine being particularly preferred. The amount of neutralizing agent used is preferably an equivalent or greater than the amount of hydrogen chloride produced. Specifically, the lower limit is usually 1.0 molar equivalent and the upper limit is preferably 2.0 molar equivalents relative to the hydrogen chloride produced.

[0020] The reaction between the alkanediol and the trimellitic anhydride halide is usually carried out using a solvent. Examples of the solvent include ether solvents such as diethyl ether, diisopropyl ether, di-n-butyl ether, tetrahydrofuran, dioxane, and t-butyl methyl ether; hydrocarbon solvents such as toluene, heptane, and cyclohexane; amide solvents such as N-methylpyrrolidone and dimethylformamide; ester solvents such as ethyl acetate and γ-butyrolactone; and ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. However, the solvent used is not particularly limited as long as the solubility of the alkanediol, trimellitic anhydride halide, and base is not affected. Furthermore, different solvents may be used for dissolving the alkanediol, the trimellitic anhydride halide, and the base. That is, a mixture of these solvents may be used.

[0021] As the solvent, tetrahydrofuran, diisopropyl ether, methyl ethyl ketone, and methyl isobutyl ketone are preferably used. If necessary, these solvents can be used in combination. In this case, the composition ratio of the solvents used is optional.

[0022] The amount of the solvent used is sufficient so long as the concentration of the alkanediol and the concentration of the trimellitic anhydride halide are each 1% by mass or more, and more preferably 5% by mass or more. The amount of the solvent used is also preferably such that the concentration of the alkanediol and the concentration of the trimellitic anhydride halide are each 50% by mass or less, and more preferably 30% by mass or less.

[0023] When carrying out the above reaction, the order of addition of each component is arbitrary and is not particularly limited. For example, when an amine is used as a neutralizing agent, a method may be used in which trimellitic anhydride halide or a solution thereof is added to a mixture of an alkanediol and an amine, or a mixed solution of these with a solvent. Alternatively, a method may be used in which a mixture of an alkanediol and an amine, or a mixed solution of these with a solvent, is added to trimellitic anhydride halide or a solution thereof. Furthermore, a method may be used in which the alkanediol and the amine are added separately to trimellitic anhydride halide or a solution thereof, or in which solutions in which the alkanediol and the amine are separately dissolved are prepared and then added. However, if heat is generated during the reaction, a decrease in purity due to side reactions may occur. Therefore, a method in which a mixed solution of an alkanediol and an amine is added dropwise to a solution of trimellitic anhydride halide is preferred.

[0024] The temperature when mixing the raw materials, and further the reaction temperature, is usually preferably between -10°C and 25°C, more preferably between 15°C and 20°C. If the reaction temperature exceeds 25°C, the amount of by-products tends to increase. The reaction time is not particularly limited. For example, if the reaction is too fast, it may end immediately after the raw materials are added. Therefore, it is usually preferable for the reaction to be within 3 hours, and more preferably 1 hour.

[0025] [Purification step of the produced trimellitic anhydride ester] After the reaction step A, the crude trimellitic anhydride ester obtained is purified. This step includes at least a step of mixing the crude trimellitic anhydride ester with a poor solvent having an octanol / water partition coefficient of -2.0 to 0.0 and a boiling point of 40°C to 120°C to reprecipitate the crude trimellitic anhydride (hereinafter also referred to as "reprecipitation step B"), and a step of heating the mixture containing at least the crude trimellitic anhydride ester after reprecipitation and acetic anhydride to recrystallize it, thereby obtaining the desired trimellitic anhydride ester (the trimellitic anhydride ester represented by the general formula (2)) (hereinafter also referred to as "recrystallization step C"). These steps can increase the purity of the trimellitic anhydride ester. However, other steps may be performed in addition to these steps in the purification step.

[0026] For example, when a neutralizing agent is used in the above reaction step A, it is preferable to carry out a step of removing the neutralizing agent before the reprecipitation step B. When a neutralizing agent such as an amine is used, its hydrochloride is generated and is removed by filtration or the like. When no neutralizing agent is used, it is preferable to remove as much dissolved hydrogen chloride gas as possible from the system by bubbling with nitrogen gas or by stirring under heat before carrying out the reprecipitation step B.

[0027] (Reprecipitation step B) The term "reprecipitation" as used herein refers to a method in which the solvent is distilled off from the reaction solution obtained in the above-mentioned reaction step to extract a solid (crude trimellitic anhydride ester). The crude trimellitic anhydride ester is then mixed with a poor solvent and the solid (crude trimellitic anhydride ester) is recovered again by filtration or the like. Note that the crude trimellitic anhydride ester referred to here usually includes not only the trimellitic anhydride ester represented by the above-mentioned general formula (2), but also its ring-opened product, impurities, and the like.

[0028] The poor solvent used in the reprecipitation step B has a predetermined octanol / water partition coefficient (hereinafter also referred to as "Pow"). The octanol / water partition coefficient (Pow) refers to the ratio of the equilibrium concentrations of a substance (here, solvent) dissolved in two phases consisting of two immiscible solvents, octanol and water. In this specification, the value is measured by the shake-flask method for measuring the partition coefficient (1-octanol / water) according to the Japanese Industrial Standard (JIS Z 7260-107 (2000)). The poor solvent used in the reprecipitation step B has a Pow of -2.0 or more and 0.0 or less. If the Pow is 0.0 or more, the target trimellitic anhydride ester will dissolve, resulting in a decrease in purity. In addition, chlorine may not be sufficiently removed, leading to a decrease in quality. In contrast, if the Pow is -2.0 or more and 0.0 or less, the trimellitic anhydride ester can be reprecipitated without dissolving. Pow is -2.0 or more, preferably -1.5 or more, and 0.0 or less, preferably -0.2 or less.

[0029] In the reprecipitation step B, the poor solvent used satisfies the above Pow and has a boiling point of 40°C or higher and 120°C or lower under atmospheric pressure. If the boiling point is lower than 40°C, handling at room temperature becomes difficult. On the other hand, if the boiling point is higher than 120°C, the solvent cannot be sufficiently removed by drying, which may result in a decrease in yield in the subsequent recrystallization step C. The boiling point is 40° C. or higher, preferably 60° C. or higher, and more preferably 80° C. or higher, and 120° C. or lower, preferably 105° C. or lower. The poor solvent used in the reprecipitation step B may be a single solvent or a mixture of two or more solvents. When two or more solvents are used, all of them should satisfy the above-mentioned Pow and boiling point.

[0030] Examples of poor solvents having a Pow of -2.0 or more and a boiling point of 40°C or more and 120°C or less include water (Pow = -1.38, boiling point 100°C), methanol (Pow = -0.66, boiling point 64.7°C), ethanol (Pow = -0.38, boiling point 78°C), acetonitrile (Pow = -0.30, boiling point 82°C), 1,4-dioxane (Pow = -0.27, boiling point 101°C), and acetone (Pow = -0.24, boiling point 56°C). Among these, solvents having a Pow range of -2.0 or more and a boiling point of 40°C or more and 100°C or less are preferred, with water, methanol, ethanol, and acetonitrile being more preferred. From the viewpoints of solvent removal efficiency and purity, water and acetonitrile are more preferred, with acetonitrile being particularly preferred.

[0031] The temperature at which the reprecipitation step B is carried out, i.e., the temperature at which the crude trimellitic anhydride ester obtained in the reaction step A is mixed with the poor solvent, is preferably 0° C. or higher and 20° C. or lower, more preferably 0° C. or higher and 10° C. If the temperature exceeds 20° C., a side reaction may occur, which may result in a decrease in purity.

[0032] The amount of the poor solvent used is preferably 3 to 6 times, and more preferably 4 to 5 times, the theoretical yield of the trimellitic anhydride ester in Reaction Step A. After reprecipitation, the solid may be recovered by filtration and washed again with the poor solvent or filtered. Thereafter, if necessary, the mixture is heated under normal pressure or reduced pressure, and the poor solvent is distilled off to obtain a crude trimellitic anhydride ester.

[0033] (Recrystallization process C) In the recrystallization step C, a mixed solution containing at least the crude trimellitic anhydride ester obtained after the reprecipitation step B and acetic anhydride is heated, and then the trimellitic anhydride ester is recrystallized. As described above, the crude trimellitic anhydride ester usually contains a ring-opened product of the trimellitic anhydride ester in part. Therefore, by mixing the crude trimellitic anhydride ester with acetic anhydride and heating, the ring-opened portion of the trimellitic anhydride ester is closed. Therefore, the purity of the obtained trimellitic anhydride ester is further increased.

[0034] On the other hand, recrystallization is an operation of dissolving a crude trimellitic anhydride ester in a predetermined solvent and precipitating the trimellitic anhydride ester again as crystals, and refers to a method of cooling a saturated solution of the trimellitic anhydride ester at a high temperature, a method of adding another solvent to the solution to reduce the solubility, etc. The ring closure and recrystallization may be carried out separately, but are preferably carried out successively from the viewpoint of efficiency.

[0035] Any solvent can be used for recrystallization as long as it dissolves the trimellitic anhydride ester when heated and precipitates crystals after cooling. For example, acetic anhydride, which is used for ring closure, can be used. Suitable poor solvents include aromatic hydrocarbon compounds such as toluene and xylene; aliphatic hydrocarbon compounds such as hexane and heptane; ether compounds such as diethyl ether, tetrahydrofuran, and diethylene glycol dimethyl ether; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and carboxylic acid anhydride solvents such as propionic anhydride. However, as mentioned above, acetic anhydride is particularly preferred because it can improve purity through chemical ring closure and can also recrystallize the trimellitic anhydride ester. The solvents may be used alone or in combination of two or more. When multiple solvents are combined, the composition ratio of the solvents used is arbitrary.

[0036] Here, during the ring closure, it is preferable to mix 160 to 230 parts by mass of acetic anhydride per 100 parts by mass of crude trimellitic anhydride ester. Furthermore, 15 parts by mass or less of a poor solvent may be mixed. If the amount of acetic anhydride is less than 160 parts by mass, the ring closure reaction cannot be carried out sufficiently, resulting in a decrease in purity. However, if the amount is 160 parts by mass or more, the ring closure reaction can be carried out efficiently. Furthermore, if the amount exceeds 230 parts by mass, a decrease in purity may occur. However, if the amount is 230 parts by mass or less, such a decrease in purity is unlikely to occur. The amount of acetic anhydride is more preferably 180 to 220 parts by mass, and even more preferably 190 to 210 parts by mass, per 100 parts by mass of crude trimellitic anhydride ester. Furthermore, if the amount of poor solvent exceeds 15 parts by mass, subsequent recrystallization may not proceed sufficiently, resulting in a further decrease in purity. On the other hand, if the amount is 15 parts by mass or less, recrystallization is more likely to proceed and the purity is likely to increase. The amount of the poor solvent is more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less, relative to 100 parts by mass of the crude trimellitic anhydride ester.

[0037] The temperature of the ring-closure reaction is preferably 80°C or higher and 110°C or lower, and more preferably 90°C or higher and 100°C or lower. If the temperature is lower than 80°C, redissolution may be insufficient, but if the temperature is 80°C or higher, the crude trimellitic anhydride ester can be easily dissolved in acetic anhydride or other solvents. If the temperature is higher than 110°C, impurities may be generated, but if the temperature is 110°C or lower, such impurities are less likely to be generated, and a highly pure trimellitic anhydride ester can be easily obtained.

[0038] After the heating, the mixture is cooled to recrystallize the trimellitic anhydride ester. After the recrystallization, the crystals of the trimellitic anhydride ester are recovered by filtration or the like. Since the obtained purified product may contain the solvent used, it is preferable to remove the solvent and dry the product. The method for removing the solvent is not particularly limited, but examples include a method in which the solvent is distilled off by heating under normal pressure or reduced pressure.

[0039] (analysis) The compounds obtained by the above methods were identified using a nuclear magnetic resonance (NMR) spectrometer and HPLC based on the change in peak intensity before and after the reprecipitation step B and the change in peak intensity before and after the ring closure in the recrystallization step C. [Example]

[0040] The present invention will be described in more detail below with reference to examples, but the present invention will not depart from the gist of the invention. The present invention is not limited to the following examples.

[0041] 1. Preparation of Trimellitic Anhydride Esters Example 1 (Reaction Step A) 100.0 g (0.47 mol) of trimellitic anhydride chloride was dissolved in 356.1 g of tetrahydrofuran (THF) and placed in a reactor under nitrogen and cooled to 15°C in a water bath. A solution of 17.35 g (0.23 mol) of 1,3-propanediol and 41.3 g (0.52 mol) of pyridine in 534.2 g of THF was added dropwise over 30 minutes. During this time, pyridine hydrochloride precipitated, and the internal temperature of the reaction solution rose to 19°C. The reaction was continued for another hour while maintaining this temperature. After completion of the reaction, the pyridine hydrochloride was filtered off, and the resulting filtrate was distilled under reduced pressure at 300 mmHg and 60°C until a slurry was obtained. At this point, 178.1 g of THF remained.

[0042] (Reprecipitation step B) The slurry (containing crude trimellitic anhydride ester) was added to 483.6 g of acetone (Pow=-0.24, boiling point 56°C) at 10°C, and the crystals were separated by filtration. Then, the crystals were dried under reduced pressure to obtain white crystals.

[0043] (Recrystallization process C) The white crystals thus obtained were further purified. Specifically, 180.8 g of acetic anhydride was added to the white crystals, and the mixture was heated to 85°C to completely dissolve them. After the crystals were completely dissolved, the mixture was stirred for 2 hours and allowed to cool to precipitate crystals. The precipitated crystals were filtered and then dried under reduced pressure. This gave white crystals (trimellitic anhydride ester).

[0044] <Example 2> (Reaction Step A) 150.0 g (0.71 mol) of trimellitic anhydride chloride was dissolved in 427.3 g of THF, charged into a reactor under nitrogen, and cooled to 15°C in a water bath. A solution of 42.1 g (0.36 mol) of 1,6-hexanediol and 62.0 g (0.78 mol) of pyridine dissolved in 801.2 g of THF was added dropwise over 30 minutes. The subsequent steps were carried out in the same manner as in Example 1.

[0045] (Reprecipitation step B) The same procedure as in Example 1 was carried out, except that the above slurry was added to 830.6 g of ethanol (Pow=-0.38, boiling point 78°C) at 10°C.

[0046] (Recrystallization process C) To the obtained crystals, 293.8 g of acetic anhydride was added, and the same operation as in Example 1 was carried out except that the heating temperature (ring closure temperature) was changed to 90° C., thereby obtaining white crystals (trimellitic anhydride ester).

[0047] Example 3 (Reaction Step A) 120.0 g (0.57 mol) of trimellitic anhydride chloride was dissolved in 427.3 g of THF, charged into a reactor under nitrogen, and cooled to 15°C in a water bath. A solution of 42.1 g (0.36 mol) of 1,10-decanediol and 62.0 g (0.78 mol) of pyridine dissolved in 801.2 g of THF was added dropwise over 30 minutes. The subsequent steps were carried out in the same manner as in Example 1.

[0048] (Reprecipitation step B) The same procedure as in Example 1 was carried out, except that the slurry was added to 830.6 g of water (Pow=-1.38, boiling point 100°C) at 5°C.

[0049] (Recrystallization process C) To the obtained crystals, 251.1 g of acetic anhydride was added, and the same operation as in Example 1 was carried out except that the heating temperature (ring closure temperature) was changed to 95° C., thereby obtaining white crystals (trimellitic anhydride ester).

[0050] Example 4 (Reaction Step A) 120.0 g (0.57 mol) of trimellitic anhydride chloride was dissolved in 427.3 g of THF, charged into a reactor under nitrogen, and cooled to 15°C in a water bath. A solution of 42.1 g (0.36 mol) of 1,10-decanediol and 62.0 g (0.78 mol) of pyridine dissolved in 801.2 g of THF was added dropwise over 30 minutes. The subsequent reaction steps were carried out in the same manner as in Example 1.

[0051] (Reprecipitation step B) The same procedure as in Example 1 was carried out, except that the slurry was added to 830.6 g of acetonitrile (Pow=-0.30, boiling point 82°C) at 5°C.

[0052] (Recrystallization process C) To the obtained crystals, 251.1 g of acetic anhydride was added, and the same operation as in Example 1 was carried out except that the heating temperature (ring closure temperature) was changed to 95° C., thereby obtaining white crystals (trimellitic anhydride ester).

[0053] <Example 5> (Reaction Step A) 90.0 g (0.43 mol) of trimellitic anhydride chloride was dissolved in 320.5 g of THF, charged into a reactor under nitrogen, and cooled to 15°C in a water bath. A solution of 41.5 g (0.21 mol) of 1,12-dodecanediol and 37.2 g (0.47 mol) of pyridine dissolved in 489.7 g of THF was added dropwise over 30 minutes. The subsequent steps were carried out in the same manner as in Example 1.

[0054] (Reprecipitation step B) The same procedure as in Example 1 was carried out, except that the slurry was added to 564.8 g of methanol (Pow=-0.66, boiling point 65°C) at 10°C.

[0055] (Recrystallization process C) To the obtained crystals, 216.2 g of acetic anhydride was added, and the same operation as in Example 1 was carried out except that the heating temperature (ring closure temperature) was changed to 100° C., thereby obtaining white crystals (trimellitic anhydride ester).

[0056] Example 6 (Reaction Step A) 70.0 g (0.33 mol) of trimellitic anhydride chloride was dissolved in 249.3 g of THF, charged into a reactor under nitrogen, and cooled to 15°C in a water bath. A solution of 41.2 g (0.16 mol) of 1,16-hexadecanediol and 28.9 g (0.37 mol) of pyridine dissolved in 373.9 g of THF was added dropwise over 30 minutes. The subsequent steps were carried out in the same manner as in Example 1.

[0057] (Reprecipitation step B) The same procedure as in Example 1 was carried out, except that the slurry was added to 484.0 g of acetonitrile (Pow=-0.30, boiling point 82°C) at 15°C.

[0058] (Recrystallization process C) To the obtained crystals, 153.3 g of acetic anhydride was added, and the same operation as in Example 1 was carried out except that the heating temperature (ring closure temperature) was changed to 105° C., thereby obtaining white crystals (trimellitic anhydride ester).

[0059] <Comparative Example 1> (Reaction Step A) 80.0 g (0.38 mol) of trimellitic anhydride chloride was dissolved in 284.9 g of THF, charged into a reactor under nitrogen, and cooled to 15°C in a water bath. A solution of 13.9 g (0.18 mol) of 1,4-butanediol and 33.1 g (0.42 mol) of pyridine dissolved in 427.3 g of THF was added dropwise over 30 minutes. The subsequent steps were carried out in the same manner as in Example 1.

[0060] (Reprecipitation step B) The same procedure as in Example 1 was carried out, except that the slurry was added to 386.9 g of toluene (Pow=2.73, boiling point 111°C) at 15°C.

[0061] (Recrystallization process C) To the obtained crystals, 117.7 g of acetic anhydride was added, and the same operation as in Example 1 was carried out except that the heating temperature (ring closure temperature) was changed to 115° C., thereby obtaining white crystals (trimellitic anhydride ester).

[0062] <Comparative Example 2> (Reaction Step A) 90.0 g (0.43 mol) of trimellitic anhydride chloride was dissolved in 320.5 g of THF, charged into a reactor under nitrogen, and cooled to 15°C in a water bath. A solution of 41.5 g (0.21 mol) of 1,12-dodecanediol and 37.2 g (0.47 mol) of pyridine dissolved in 480.7 g of THF was added dropwise over 30 minutes. The subsequent steps were carried out in the same manner as in Example 1.

[0063] (Reprecipitation step B) The same procedure as in Example 1 was carried out, except that the slurry was added to 564.8 g of dimethylacetamide (Pow=-0.77, boiling point 165°C) at 20°C.

[0064] (Recrystallization process C) To the obtained crystals, 194.3 g of acetic anhydride was added, and the same operation as in Example 1 was carried out except that the heating temperature (ring closure temperature) was changed to 85° C., thereby obtaining white crystals (trimellitic anhydride ester).

[0065] <Comparative Example 3> (Reaction Step A) 60.0 g (0.28 mol) of trimellitic anhydride chloride was dissolved in 213.7 g of THF, charged into a reactor under nitrogen, and cooled to 15°C in a water bath. A solution of 35.4 g (0.14 mol) of 1,16-hexadecanediol and 24.8 g (0.31 mol) of pyridine in 320.5 g of THF was added dropwise over 30 minutes. The subsequent steps were carried out in the same manner as in Example 1.

[0066] (Reprecipitation step B) The same procedure as in Example 1 was carried out, except that the slurry was added to 414.9 g of ethyl acetate (Pow=0.73, boiling point 77°C) at 5°C.

[0067] (Recrystallization process C) To the obtained crystals, 93.8 g of acetic anhydride was added, and the same operation as in Example 1 was carried out except that the heating temperature (ring closure temperature) was changed to 95° C., thereby obtaining white crystals (trimellitic anhydride ester).

[0068] <Comparative Example 4> (Reaction Step A) 30.0 g (0.14 mol) of trimellitic anhydride chloride was dissolved in 106.8 g of THF, charged into a reactor under nitrogen, and cooled to 15°C in a water bath. A solution of 19.3 g (0.07 mol) of 1,20-icosanediol and 12.4 g (0.16 mol) of pyridine dissolved in 160.3 g of THF was added dropwise over 30 minutes. The subsequent steps were carried out in the same manner as in Example 1.

[0069] (Reprecipitation step B) The same procedure as in Example 1 was carried out, except that the slurry was added to 215.7 g of acetone (Pow=-0.24, boiling point 56°C) at 15°C.

[0070] (Recrystallization process C) To the obtained crystals, 82.4 g of acetic anhydride was added, and the same operation as in Example 1 was carried out except that the heating temperature (ring closure temperature) was changed to 100° C., thereby obtaining white crystals (trimellitic anhydride ester).

[0071] 2.Analysis The trimellitic anhydride esters obtained in the examples and comparative examples were analyzed as follows.

[0072] (1) Yield The yield was calculated based on the following formula: The amount obtained as the final product was taken as the production volume, and the theoretical yield was the value obtained by multiplying the moles of the raw materials charged by the molecular weight of the target product. Yield = Volume / Theoretical Yield x 100 And it was evaluated according to the following criteria.

[0073] <Evaluation criteria> ◎: 80% or more ○: 70% or more but less than 80% ×: Less than 70%

[0074] (2) Purity analysis by high performance liquid chromatography The purity of the obtained trimellitic anhydride ester was analyzed by the following method. Equipment: Shimadzu high-performance liquid chromatograph Detector: Ultraviolet absorption photometer (measurement wavelength 254 nm) Column: YMC-PackODS-A Column temperature: 40℃ Flow rate: 1.0mL / min Measurement time: 20 min Eluent: Acetonitrile / 0.1% phosphoric acid aqueous solution = 60 / 40 (v / v) Sample preparation: (i) 0.35 g of aniline and 0.90 g of NMP were weighed out, 0.10 g of a sample was added, and the mixture was stirred for 1 hour to convert it into an anilide derivative. (ii) 0.4 g of the obtained anilide derivative solution was diluted with 3 mL of the eluent to prepare a measurement solution. The purity was determined from the measured values ​​based on the following formula: Purity (%) = (area of ​​target substance / area of ​​target substance, 1st ring-opened substance, 2nd ring-opened substance) x 100 The calculated purity was evaluated according to the following criteria.

[0075] <Evaluation criteria> ◎: 99% or more ○: 97% or more and less than 99% ×: Less than 97%

[0076] (3) Analysis of chlorine content by potentiometric titration The chlorine content was analyzed by potentiometric titration using the following method. Equipment: Hiranuma automatic titrator COM-1700 Eluent: THF / 30% nitric acid = 60 / 10 (mL) Titrant: 0.002M silver nitrate aqueous solution (2mM silver nitrate aqueous solution) Based on the obtained values, evaluation was made according to the following criteria.

[0077] <Evaluation criteria> ◎: Less than 10 ppm ○: 10 ppm or more and less than 20 ppm ×: 20 ppm or more

[0078] 3.Results The results are shown in Table 1 below. [Table 1]

[0079] The trimellitic anhydride esters prepared in Examples 1 to 6 were all produced in high yields with high purity, and the chlorine content was an extremely low value of less than 17 ppm.

[0080] The trimellitic anhydride ester prepared in Comparative Example 1 used toluene (Pow = 2.73) which has a high octanol / water partition coefficient, so the target product dissolved in the reprecipitation step B, resulting in a low yield. Furthermore, in Comparative Example 1, the chlorine content was high.

[0081] In the trimellitic anhydride ester prepared in Comparative Example 2, the boiling point of the dimethylacetamide used in the reprecipitation step B was as high as 165°C, and therefore a large amount of the dimethylacetamide remained in the recrystallization step C, resulting in a reduced yield.

[0082] The trimellitic anhydride ester prepared in Comparative Example 3 used ethyl acetate (Pow = 0.73) with a high octanol / water partition coefficient, so the target product dissolved in the reprecipitation step B, resulting in a reduced yield and a high chlorine content.

[0083] The trimellitic anhydride ester prepared in Comparative Example 4 had a good yield and a good chlorine content because the starting alkanediol had a large carbon number of 20, but the purity was reduced due to a decrease in reactivity. [Industrial Applicability]

[0084] The trimellitic anhydride ester obtained by the present invention can be used as a raw material for heat-resistant resins such as polyimide and polyamic acid, and can also be advantageously used as a curing agent for epoxy resins and polyurethane resins. In particular, since a high-purity product can be obtained by the present invention, it can be used in electronic component materials and optical applications, for which high purity quality has been required in recent years.

Claims

1. A step A of reacting a trimellitic anhydride halide with an alkanediol represented by the following general formula (1) to obtain a crude trimellitic anhydride ester including a trimellitic anhydride ester represented by the following general formula (2); 【Chemistry 1】 (In general formula (1), R １ represents a linear alkylene group having 2 to 16 carbon atoms. 【Chemistry 2】 (In general formula (2), R １ represents a linear alkylene group having 2 to 16 carbon atoms) and purifying the crude trimellitic anhydride ester, The step of purifying the crude trimellitic anhydride includes a step B of mixing the crude trimellitic anhydride with a poor solvent having an octanol / water partition coefficient of −2.0 or more and 0.0 or less and a boiling point of 40° C. or more and 120° C. or less, and reprecipitating the crude trimellitic anhydride; a step C of heating a mixture of the crude trimellitic anhydride ester after precipitation and acetic anhydride, and then recrystallizing the trimellitic anhydride ester; A method for producing a trimellitic anhydride ester, comprising:

2. The step B is carried out at a temperature ranging from 0°C to 20°C. The method for producing trimellitic anhydride ester according to claim 1.

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