Method for producing trichloride trimesinate

Abstract

This invention provides a novel method for producing high-purity trimeciate trichloride, which can be obtained with volumetric efficiency and in good yield. [Solution] A method for producing trimeciate trichloride, comprising the steps of (I) reacting trimesic acid with the following compound (B) in the presence of at least one catalyst, iron(III) chloride, zinc oxide, and zinc chloride, and (II) separating the reaction product obtained in step (I) by distillation. Compound (B): 1,3-bis(trichloromethyl)benzene or 1,4-bis(trichloromethyl)benzene

Description

Technical Field

[0001] The present invention relates to a method for producing trimesic acid trichloride.

Background Art

[0002] Trimesic acid trichloride is expected to be used as an intermediate for pharmaceuticals, agricultural chemicals, etc., and also as a monomer for producing functional polymers such as aromatic polyamides and aromatic polyimides.

[0003] As a general method for producing trimesic acid trichloride, many methods are known in which trimesic acid is chlorinated with thionyl chloride. However, in this method, thionyl chloride with a strong pungent odor is used, and it is necessary to treat the by-produced sulfur dioxide, and there is a problem that a sulfur component is mixed into the product. Also, a method using oxalyl chloride as a chlorinating agent is known, but oxalyl chloride is expensive and there is also a problem in that it is necessary to treat the by-produced carbon monoxide and carbon dioxide.

[0004] Further, not limited to trimesic acid trichloride, as a general method for producing an aromatic carboxylic acid chloride, an aromatic carboxylic acid and benzene substituted with a trichloromethyl group are heated in the presence of a zinc or iron compound to convert them into an aromatic carboxylic acid chloride and benzoyl chloride, and they are separated by distillation (Patent Document 1, etc.). According to this method, by-products other than hydrogen chloride do not occur, and the problem of the above by-products does not occur. As a method for producing trimesic acid trichloride using benzene substituted with the above trichloromethyl group as a chlorinating agent, for example, Patent Documents 2 to 3 describe a production method by a chlorine-oxygen exchange reaction between trimesic acid and (trichloromethyl)benzene (alias: benzotrichloride) using zinc oxide as a catalyst. Also, Patent Document 4 describes a method in which 1 molar equivalent of trimesic acid and 1 molar equivalent of 1,3,5-tris(trichloromethyl)benzene are subjected to an exchange reaction to produce 2 molar equivalents of trimesic acid trichloride. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] British Patent Application Publication No. 949574 [Patent Document 2] Japanese Patent Publication No. 2011-046664 [Patent Document 3] Japanese Patent Publication No. 2013-053100 [Patent Document 4] Chinese Patent Application Publication No. 104592012 Specification [Overview of the project] [Problems that the invention aims to solve]

[0006] However, as a result of our investigations, the present inventors have found that in the methods described in Patent Documents 2 and 3, while zinc oxide is used as a catalyst to heat trimesic acid and (trichloromethyl)benzene to convert them into trimesic acid trichloride and benzoyl chloride, and then these are separated by distillation, the problem is that benzoyl chloride has a low boiling point and is often sucked into the vacuum pump, causing equipment problems. To avoid this problem, it is also conceivable to distill off benzoyl chloride by reducing the degree of vacuum and then distill off trimesic acid trichloride by increasing the vacuum, but this makes the distillation operation complicated, and it is practically impossible to obtain a trimesic acid trichloride component before distillation that is completely free of benzoyl chloride. Furthermore, it is necessary to use (trichloromethyl)benzene in a stoichiometric ratio of 3 molar equivalents or more per 1 molar equivalent of trimesic acid. In addition, there is the drawback that self-condensation (the so-called Friedel-Crafts reaction) is likely to occur when benzoyl chloride is heated to high temperatures in the presence of zinc or iron compounds. Furthermore, in the method described in Patent Document 4, the chlorinating agent 1,3,5-tris(trichloromethyl)benzene is usually obtained by photochlorination of 1,3,5-trimethylbenzene. However, this requires a long reaction time, and the electron density of the aromatic ring increases, resulting in the generation of a large amount of nuclear chloride as a by-product. As shown in the reference example described later, a large amount of nuclear chloride (approximately 52%) is already generated in the early stages of the reaction, making it extremely difficult to obtain 1,3,5-tris(trichloromethyl)benzene in good yield. Moreover, removing the nuclear chloride by distillation requires advanced rectification equipment because the boiling points of 1,3,5-tris(trichloromethyl)benzene and the nuclear chloride are close. Therefore, it is extremely difficult to obtain a high-purity product in good yield by distillation purification. Furthermore, in the subsequent synthesis of trimesic acid trichloride, the nuclear chloride contained as an impurity in 1,3,5-tris(trichloromethyl)benzene also reacts, producing nuclear chlorinated trimesic acid trichloride. As described above, the conventional methods for producing trimethic acid trichloride described in Patent Documents 2 to 4, which use (trichloromethyl)benzene or 1,3,5-tris(trichloromethyl)benzene as a chlorinating agent, have various problems, and a new method for producing trimethic acid trichloride is needed from the perspective of industrial implementation.

[0007] Therefore, the object of the present invention is to provide a novel method for producing trimeciate trichloride that can obtain high-purity trimeciate trichloride efficiently and in good yield. [Means for solving the problem]

[0008] In view of the above problems, the inventors have conducted extensive studies on the chlorine-oxygen exchange reaction for obtaining trimesic acid trichloride from the perspective of chlorinating agents and catalysts. As a result, they have found that by reacting 1 molar equivalent of trimesic acid with 1.5 molar equivalents (stoichiometric ratio) of 1,3-bis(trichloromethyl)benzene or 1,4-bis(trichloromethyl)benzene as a chlorinating agent that can be prepared in high yield, in the presence of at least one of iron(III) chloride, zinc oxide, and zinc chloride as a catalyst, distillation separation can be carried out smoothly, and high-purity trimesic acid trichloride can be obtained in good yield with volume efficiency. Furthermore, the inventors have found that the above method produces isophthalic acid chloride or terephthalic acid chloride, which are useful as polymer monomers for producing aramid resins, etc., as by-products, and that these by-products can also be obtained in high purity and good yield by distillation separation. This invention was completed based on these findings.

[0009] In other words, the above problem was solved by the following means. [1] A method for producing trimeciate trichloride, comprising the steps of (I) reacting trimesic acid with the following compound (B) in the presence of at least one catalyst, iron(III) chloride, zinc oxide, and zinc chloride, and (II) separating the reaction product obtained in step (I) by distillation. Compound (B): 1,3-bis(trichloromethyl)benzene or 1,4-bis(trichloromethyl)benzene [2] A method for producing trimecinate trichloride according to [1], wherein the catalyst is iron(III) chloride. [3] A method for producing trimecinate trichloride according to [1] or [2], wherein the compound (B) is 1,3-bis(trichloromethyl)benzene. [4] A method for producing trimethic acid trichloride as described in [3], wherein the purity of the 1,3-bis(trichloromethyl)benzene is 98.0% or higher. [5] The method for producing trimethic acid trichloride according to [4], wherein the 1,3-bis(trichloromethyl)benzene mentioned above is 1,3-bis(trichloromethyl)benzene with a purity of 98.0% or more obtained by photochlorinating metaxylene and separating it by rectification. [6] A method for producing trimethic acid trichloride according to any one of [1] to [5], wherein the reaction in step (I) above contains 0.5 to 2.0 molar equivalents of isophthalic acid chloride or terephthalic acid chloride per 1 molar equivalent of the above trimesic acid in the reaction system.

[0010] In this invention, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. [Effects of the Invention]

[0011] According to the manufacturing method of the present invention, high-purity trimeciate trichloride can be obtained in a volume-efficient manner and in good yield using a novel method more suitable for industrial implementation. [Modes for carrying out the invention]

[0012] [Method for producing trichloride trimesinate] The present invention provides a method for producing trimeciate trichloride (hereinafter also referred to as "the present invention's method") which comprises the steps of reacting trimeciate with the following compound (B) in the presence of at least one catalyst (also referred to simply as "catalyst"), which consists of iron(III) chloride, zinc oxide, and zinc chloride (also referred to as "the catalyst") (also referred to as "step (I)") and separating the reaction product obtained in step (I) by distillation (also referred to as "step (II)"). Compound (B): 1,3-bis(trichloromethyl)benzene or 1,4-bis(trichloromethyl)benzene The reaction product obtained by step (I) above includes trimeciate trichloride, which is the target product in the production method of the present invention, and isophthalate chloride or terephthalate chloride, which are by-products derived from compound (B). By a simple purification process of distillation separation of the reaction product obtained by step (I), high-purity trimeciate trichloride can be obtained in good yield, and isophthalate chloride or terephthalate chloride can also be obtained in high purity and good yield. Specifically, isophthalic acid chloride and terephthalic acid chloride, which can be produced as by-products in the production method of the present invention, have higher boiling points than benzoyl chloride, which is produced as a by-product in the production methods described in Patent Documents 2 and 3. Therefore, in the production method of the present invention, distillation is possible without requiring complex operating procedures. Furthermore, since isophthalic acid chloride and terephthalic acid chloride have similar boiling points to trimesic acid trichloride, rectification separation using an industrial distillation column can be performed without complex operating procedures. Moreover, according to the production method of the present invention, isophthalic acid chloride or terephthalic acid chloride, which are commercially useful by-products as raw materials for polymer materials such as aramid resins, can be obtained in high purity and good yield as by-products in the production of trimesic acid trichloride. Furthermore, in the chlorine-oxygen exchange reaction of step (I) described above, 1.5 molar equivalents of compound (B), which is the chlorinating agent, are sufficient for 1 molar equivalent of trimesic acid (this is a stoichiometric ratio, and the acceptable amount to use is 1.45 molar equivalents), thus demonstrating superior volumetric efficiency compared to the manufacturing methods described in Patent Documents 2 to 3. Furthermore, unlike 1,3,5-tris(trichloromethyl)benzene, which is the chlorinating agent in the manufacturing method described in Patent Document 4, compound (B), which is the chlorinating agent, can be obtained by a normal chlorination reaction using metaxylene or paraxylene as a raw material, with almost no by-production of nuclear chlorinated products, and can be prepared in high yield (for example, 85% or more, preferably 90% or more, more preferably 92% or more). As a result, the manufacturing method of the present invention can produce high-purity trimecinate trichloride with volume efficiency and in good yield. Hereinafter, each of the steps (I) and (II) will be described in detail.

[0013] [Step (I)] The reaction between trimesic acid and the above compound (B) is carried out by mixing and heating both in the presence of the above catalyst. By this reaction, theoretically, 1 molar equivalent of trimesic acid trichloride and 1.5 molar equivalents of isophthalic acid chloride or terephthalic acid chloride are produced with respect to 1 molar equivalent of the charged trimesic acid and 1.5 molar equivalents of the compound (B). When 1,3-bis(trichloromethyl)benzene is used as the compound (B), isophthalic acid chloride is produced, and when 1,4-bis(trichloromethyl)benzene is used as the compound (B), terephthalic acid chloride is produced, respectively. In the step (I) of reacting trimesic acid with the above compound (B) in the presence of the above catalyst, the reaction conditions (reaction temperature, reaction time, reaction solvent, etc.) can be appropriately adjusted so that the target trimesic acid trichloride can be obtained in a good yield and the trimesic acid trichloride can be obtained in a high purity in the next step (II).

[0014] From the viewpoint of volume efficiency, usually, it is advantageous to carry out the reaction under solvent-free (without containing a solvent) conditions, and the above step (I) can also be carried out under solvent-free conditions. On the other hand, in the production method of the present invention, in the reaction of the above step (I), by containing (adding in advance) the acid chloride of isophthalic acid chloride or terephthalic acid chloride obtained as a by-product of the step (I) in the reaction system as a solvent, the reaction can be promoted, which is preferable. This is because at the start of the reaction in the step (I), the solid trimesic acid and the above compound (B) exist as a heterogeneous system, but by containing isophthalic acid chloride or terephthalic acid chloride as a solvent, the acid anhydride of trimesic acid is generated, and it is presumed that the reaction proceeds more easily. As evidence of this, in Examples 3 and 4 described later, it was confirmed that when the reaction without a solvent proceeds a little and isophthalic acid chloride or terephthalic acid chloride, which is a by-product of the step (I), starts to be formed, the reaction rate increases rapidly. Regarding whether isophthalate chloride or terephthalate chloride should be included in the reaction system, the same compound as the isophthalate chloride or terephthalate chloride produced as a byproduct in step (I) should be included, depending on compound (B). For example, if compound (B) is 1,3-bis(trichloromethyl)benzene, the isophthalate chloride obtained as a byproduct in step (I) should be included. In the reaction of step (I) described above, the amount of isophthalic acid chloride or terephthalic acid chloride to be included in the reaction system is usually preferably 0.5 to 2.0 molar equivalents, more preferably 0.7 to 1.5 molar equivalents, and even more preferably 0.7 to 1.2 molar equivalents, per 1 molar equivalent of trimesic acid.

[0015] Furthermore, the improvement in reaction rate by adding acid chloride, a by-product of step (I) above, as a solvent is not limited to the method for producing trimecinic acid trichloride of the present invention using compound (B) above, but is also effective when using chlorinating agents other than compound (B) above (for example, mono(trichloromethyl)benzene substituted compounds). For example, in the comparative reference example described below, the reaction between trimesic acid and (trichloromethyl)benzene in the presence of a zinc oxide catalyst hardly proceeded in comparative reference example A, in which the by-product benzoyl chloride (acid chloride) was not included in the reaction system. However, in comparative reference example B, in which benzoyl chloride was included in the reaction system as a solvent compared to comparative reference example A, it was confirmed that 99.5% of trimesic acid trichloride was produced under the same reaction conditions (reaction temperature and reaction time) as in comparative reference example A.

[0016] The reaction temperature is typically 120 to 180°C, preferably 120 to 150°C, and more preferably 120°C or higher and less than 145°C. For example, when the reaction is carried out in the presence of an iron(III) chloride catalyst, or when the above-mentioned isophthalic acid chloride or terephthalic acid chloride acid chloride is added as a solvent, or when a combination of these catalyst types and solvent addition conditions is used, the reaction temperature can be made milder, around 120 to 150°C. The reaction time varies depending on the reaction scale, temperature, presence or absence of solvent, and type and amount of catalyst, but is usually 1 to 5 hours.

[0017] Step (I) described above is carried out in the presence of at least one catalyst, which is iron(III) chloride, zinc oxide, or zinc chloride, and these catalysts function as Lewis acid catalysts (i.e., catalysts consisting of substances that accept electron pairs). Furthermore, all of these catalysts are substantially anhydrous catalysts (catalysts of anhydrous substances), and commercially available anhydrous iron(III) chloride, zinc oxide, and zinc chloride can be used as reagents. The excellent catalytic activity of iron(III) chloride is also demonstrated in the examples described below. While heating and stirring at 175°C for 3 hours was necessary to achieve a 99.9% conversion rate of trimesic acid in the presence of zinc oxide catalyst, in the presence of iron(III) chloride catalyst, a 100% conversion rate of trimesic acid was achieved even when the amount of catalyst used (molar ratio) relative to trimesic acid was reduced to approximately one-quarter of that used with zinc oxide catalyst and heating and stirring was performed at a lower temperature of 145°C for 3 hours. This shows that the reaction in step (I) above reaches its endpoint rapidly (Example 3 compared to Example 4). Furthermore, the excellent catalytic activity of iron(III) chloride is not limited to the method for producing trimecinate trichloride using compound (B) of the present invention, but is also considered to be effective when using chlorinating agents other than compound (B). For example, in Comparative Reference Example A described later, the reaction between trimesic acid and (trichloromethyl)benzene in the presence of a zinc oxide catalyst hardly proceeded under reaction conditions of 145°C for 2 hours. In Comparative Example 2, which corresponds to an example where the zinc oxide catalyst was changed to an iron(III) chloride catalyst compared to Comparative Reference Example A, it was confirmed that 91.6% of trimesic acid trichloride was produced under the same reaction conditions of 145°C for 2 hours as in Comparative Reference Example A. The amount of the above catalyst used is usually 0.01 to 2.00 mol%, preferably 0.05 to 2.00 mol%, more preferably 0.05 to 1.00 mol%, even more preferably 0.05 to 0.50 mol%, and particularly preferably 0.05 to 0.15 mol% per 100 mol% of trimesic acid. Furthermore, as shown in Comparative Examples 1 and 2 below, the sodium content of trimesic acid does not affect the progress of the reaction or the yield of trimesic acid trichloride. If the sodium content of trimesic acid is between 1 and 1000 ppm, trimesic acid trichloride can be obtained in good yield by employing the method described in this invention.

[0018] The above compound (B) should be used in an amount of 1.5 molar equivalents or more per molar equivalent of trimesic acid, in terms of stoichiometric ratio. Based on the stoichiometric ratio of the above compound (B), the acceptable amount to use is preferably 1.45 to 2.50 molar equivalents, and more preferably 1.45 to 2.30 molar equivalents, per molar equivalent of trimesic acid. The above compound (B) is 1,3-bis(trichloromethyl)benzene or 1,4-bis(trichloromethyl)benzene, and 1,3-bis(trichloromethyl)benzene is preferred from the viewpoint of the ease of distillation separation based on the difference in melting points of the phthalate chloride obtained in step (I). The purity of compound (B) above is usually sufficient to be 85.0% or higher, preferably 90.0% or higher, and more preferably 92.0% or higher. Furthermore, the isophthalic acid chloride or terephthalic acid chloride produced by the manufacturing method of the present invention are both dominant in the market as raw materials for functional polymers such as aramid resins, and are required to be compounds (monomers) with a purity of 99.8% or higher, preferably 99.9% or higher. Thus, from the viewpoint of obtaining isophthalic acid chloride or terephthalic acid chloride as a compound with a purity of 99.8% or higher, the purity of compound (B) is preferably 98.0% or higher, and more preferably 98.5% or higher. Compound (B) with a purity of 85.0% or higher can be prepared by conventional methods, for example, by photochlorinating metaxylene or paraxylene as described below. Furthermore, high-purity compound (B) with a purity of 98.0% or higher can be obtained, for example, by photochlorinating metaxylene or paraxylene as described below and separating by rectification.

[0019] (Chlorination and purification of metaxylene or paraxylene) Chlorination of the methyl groups of metaxylene or paraxylene is preferably carried out by photochlorination using ultraviolet irradiation. The temperature for photochlorination is preferably 120 to 160°C, and more preferably 130 to 150°C. The rate of chlorine bubbling is preferably 0.1 to 0.3 moles per hour per mole of total metaxylene and paraxylene. Photochlorination may be carried out without a solvent or with a solvent. If a solvent is used, it can be used without particular restriction as long as it is a solvent that is stable under the photochlorination reaction conditions (a solvent that does not generate radicals by ultraviolet light and does not react with chlorine), for example, aromatic compound solvents without alkyl groups (monochlorobenzene, 1,2-dichlorobenzene, 4-chlorobenzotrifluoride, etc.). The reaction time varies depending on the rate of chlorine bubbling and the reaction temperature, but is usually 25 to 45 hours. In addition, in the above chlorination of metaxylene or paraxylene, the by-product formation of nuclear chlorinated products is hardly produced. Therefore, by performing photochlorination using the above method, compound (B) with a purity of 85.0 to 95.0% can be obtained in a high yield of 85% or more (preferably 90% or more, more preferably 92% or more). In this invention, compound (B) before rectification separation after photochlorination is also referred to as crude compound (B) (crude 1,3-bis(trichloromethyl)benzene, crude 1,4-bis(trichloromethyl)benzene). The crude 1,3-bis(trichloromethyl)benzene obtained by photochlorination is preferably purified by distillation (rectification separation) using a rectification column. The rectification column preferably has 10 or more stages, which allows for obtaining 1,3-bis(trichloromethyl)benzene of the desired purity. The distillation column may also be packed with nickel packing or the like. The degree of reduced pressure during distillation is preferably 15 torr or less, which suppresses the decrease in yield due to polymerization reactions caused by temperature rise at the bottom of the column. The reflux ratio is preferably 2 to 5. This rectification separation allows for obtaining 1,3-bis(trichloromethyl)benzene with a purity of 98.0% or higher. Furthermore, the above description of rectification separation using crude 1,3-bis(trichloromethyl)benzene as an example can also be applied to crude 1,4-bis(trichloromethyl)benzene, except that crude 1,4-bis(trichloromethyl)benzene is used instead of crude 1,3-bis(trichloromethyl)benzene, and rectification separation can be performed in the same manner. The crude compound (B) obtained by the above photochlorination can be used directly in step (I), or it can be used after the above rectification separation.

[0020] Furthermore, the hydrogen chloride produced by the reaction in step (I) above can be removed from the reaction product before proceeding to the next step (II) by conventional methods such as blowing in nitrogen gas.

[0021] [Process (II)] The reaction product (reaction mixture) obtained in step (I) above contains trimesic acid trichloride at a content of 98-99%, excluding isophthalic acid chloride and terephthalic acid chloride. It should be assumed that hydrogen chloride is removed from the reaction product in step (I) above. The step (II) for separating the reaction product obtained in step (I) above by distillation is carried out by simple distillation followed by distillation using a rectification column (rectification separation). The vacuum level during simple distillation is preferably 15 torr or less, which allows the temperature required for distillation to be adjusted to a temperature range favorable for industrial production. Through this simple distillation, a mixture of isophthalic acid chloride or terephthalic acid chloride, which is produced from the reaction product obtained in step (I) according to compound (B), and trimesic acid trichloride is distilled off. Next, the above mixture obtained by simple distillation is subjected to distillation (rectification separation) using a rectification column. The number of stages in the rectification column is preferably 10 or more, which allows obtaining isophthalic acid chloride or terephthalic acid chloride of the desired purity, and trimesic acid trichloride of the desired purity. The degree of reduced pressure during distillation by rectification separation is preferably 10 torr or less in all cases, including the distillation of isophthalic acid chloride, terephthalic acid chloride, and trimesic acid trichloride. This suppresses the decrease in yield due to polymerization reactions caused by temperature rise at the bottom of the column. The reflux ratio is preferably 1 to 5. By step (II) described above, trimecinate trichloride can be obtained with a high purity of 98.5% or more (preferably 98.9% or more, more preferably 99.5% or more, and even more preferably 99.9% or more), and isophthalate chloride or terephthalate chloride can each be obtained with a high purity of 99.8% or more (preferably 99.9% or more). The isolation yield and purity of trimecinate trichloride obtained by the production method of the present invention, which includes steps (I) and (II) described above, vary depending on conditions such as reaction scale, number of distillation stages, and reflux ratio, but can usually be obtained in a good yield of 70.0% or more. Isophthalate chloride or terephthalate chloride can also be obtained in good yields of 78.0% or more, respectively. [Examples]

[0022] The present invention will be described in more detail below based on examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the examples shown below. The conversion rate, yield, content, production rate, and purity were determined using gas chromatography with mass spectrometry (GCMS) (detector: TCD). Commercially available trimesic acid (sodium content 1 ppm) was used.

[0023] [Example 1] Photochlorination of metaxylene and production of trimeciate trichloride using the obtained 1,3-bis(trichloromethyl)benzene in the presence of iron(III) chloride catalyst (1) Photochlorination of metaxylene 318.6 g (3.00 mol) of metaxylene was heated to 140-150°C, and chlorine was blown in at a rate of 40.5 g (0.57 mol) per hour while irradiating with ultraviolet light from a high-pressure mercury lamp to perform photochlorination of metaxylene. When 1-(dichloromethyl)-3-(trichloromethyl)benzene was no longer detectable by GC analysis, the blowing of chlorine was stopped (chlorine blowing time was approximately 35 hours), and nitrogen gas was blown in for 2 hours while maintaining the temperature at 140-150°C to expel hydrogen chloride and chlorine gas from the reaction solution, yielding 905.1 g of crude 1,3-bis(trichloromethyl)benzene (reaction solution). This reaction solution contained 92.8% 1,3-bis(trichloromethyl)benzene. (2) Production of trichloride trimesinate A mixture of 584.3 g (1.87 mol) of crude 1,3-bis(trichloromethyl)benzene obtained by the above photochlorination, 250.0 g (1.19 mol) of trimesic acid, 193.0 g (0.95 mol) of isophthalic chloride, and 0.19 g (1.2 mmol) of anhydrous iron(III) chloride was heated and stirred at 130°C for 2 hours. The temperature was then raised to 140°C and heated and stirred for another 2 hours. After maturation, nitrogen gas was blown in at 140°C for 2 hours to expel the by-product hydrogen chloride. Subsequently, the resulting reaction mixture was subjected to simple distillation. The reduced pressure during distillation was 8-15 torr, and the column temperature was 170-175°C. Next, the mixture of isophthalate chloride and trimesic acid trichloride distilled by simple distillation was rectified using a distillation column (equivalent to 10 stages). Isophthalate chloride was obtained with a purity of 99.8% at a reduced pressure of 10 torr, a column temperature of 135-140°C, and a reflux ratio of 5 (the yield of the 299.0 g of isophthalate chloride produced in the reaction, excluding the 193.0 g of isophthalate chloride initially added, was 78.7%). Next, trimesic acid trichloride was distilled at a reduced pressure of 3-5 torr and a column temperature of 150-160°C. The reflux ratio was 1-3. The yield of trichloride trimesinate was 224.0 g, with a purity of 98.9% and a yield of 70.8%.

[0024] [Example 2] Photochlorination and rectification separation of metaxylene, and production of trimeciate trichloride using the obtained 1,3-bis(trichloromethyl)benzene with a purity of 98.0% or higher in the presence of an iron(III) chloride catalyst. (1) Photochlorination and rectification separation of metaxylene Metaxylene was photochlorinated in the same manner as in Example 1 to obtain 1212 g of crude 1,3-bis(trichloromethyl)benzene. This crude was rectified using a distillation column (equivalent to 10 stages) packed with nickel packing. The degree of reduced pressure during the distillation of 1,3-bis(trichloromethyl)benzene was 4 to 10 torr, the temperature at the top of the column was 130 to 135°C, and the reflux ratio was 5. The purity of the 1,3-bis(trichloromethyl)benzene obtained by rectification was 98.7%. (2) Production of trichloride trimesinate 667.7 g (2.13 mol) of 1,3-bis(trichloromethyl)benzene obtained by the above rectification separation was mixed with 300.0 g (1.43 mol) of trimesic acid, 240.0 g (1.18 mol) of isophthalic acid chloride, and 0.12 g (0.7 mmol) of anhydrous iron(III) chloride. This mixture was heated and stirred at 130°C for 2 hours. To complete the reaction, the temperature was further increased to 140°C and heated and stirred for another 2 hours. After maturation, nitrogen gas was blown in at 140°C for 2 hours to expel the by-product hydrogen chloride. Subsequently, the obtained reaction mixture was subjected to simple distillation. The degree of reduced pressure during distillation was 8-15 torr, the temperature of the reaction mixture was 180-190°C, and the temperature at the top of the column was 170-175°C. The distillation rate in this simple distillation was 98%. Next, the mixture of isophthalate chloride and trimesic acid trichloride distilled by simple distillation was rectified using a distillation column (equivalent to 10 stages). The degree of reduced pressure during the distillation of isophthalate chloride was 10 torr, the temperature of the mixture at the bottom of the column was 160-165°C, the temperature at the top of the column was 135-140°C, and the reflux ratio was 5. Next, trimesic acid trichloride was distilled. After cutting off the first distillate, the degree of reduced pressure during the distillation of trimesic acid trichloride was 3-5 torr, the temperature at the bottom of the column was 175-200°C, the temperature at the top of the column was 150-160°C, and the reflux ratio was 1-3. The amount of isophthalate chloride obtained by rectification separation was 606.3 g (excluding the 240.0 g of isophthalate chloride initially added; the yield of the 366.3 g of isophthalate chloride produced in the reaction was 84.8%), with a purity of 99.9%. On the other hand, the amount of trimesinate trichloride obtained was 286.2 g, with a purity of 99.9% and a yield of 75.5%.

[0025] [Example 3] Production of trimeciate trichloride in the presence of iron(III) chloride catalyst using 1,4-bis(trichloromethyl)benzene A suspension of 10.0 g (47.6 mmol) of trimesic acid, 22.5 g (71.5 mmol) of 1,4-bis(trichloromethyl)benzene (99.0% purity), and 33.8 mg (0.2 mmol) of anhydrous iron(III) chloride was heated and stirred at 145°C for 3 hours. GC analysis revealed that the conversion rate of trimesic acid was 100%, and 99.5% of trimesic acid trichloride was produced.

[0026] [Example 4] Production of trichloride trimesinate in the presence of a zinc oxide catalyst using 1,3-bis(trichloromethyl)benzene A suspension of 10.0 g (47.6 mmol) of trimesic acid, 22.5 g (71.5 mmol) of 1,3-bis(trichloromethyl)benzene (99.7% purity), and 67.8 mg (0.8 mmol) of zinc oxide was heated and stirred at 175°C for 3 hours. GC analysis revealed that the conversion rate of trimesic acid was 99.9%, and 99.7% of trimesic acid trichloride was produced. In Examples 3 and 4, it was confirmed that the reaction rate increased rapidly once the solvent-free reaction had progressed slightly and the by-products of step (I), isophthalic acid chloride or terephthalic acid chloride, began to form. Furthermore, in Examples 1 and 2, the conversion rate of trimesic acid after the reaction in step (I) was 99.9%, and the production rate of trimesic acid trichloride was 99.5% or higher. In Examples 3 and 4, the conversion rate of trimesic acid after the reaction in step (I) was 99.9% or higher in both cases, and the production rate of trimesic acid trichloride was 99.5% or higher in both cases. Examples 3 and 4 showed conversion rates and production rates at a similar level to Examples 1 and 2. From this, it can be understood that in Examples 3 and 4, by further performing distillation separation in step (II), high-purity trimesic acid trichloride can be obtained in good yield at a level similar to that of Examples 1 and 2.

[0027] [Comparative Example 1] Production of trimecinate trichloride in the presence of a zinc oxide catalyst using (trichloromethyl)benzene 10.0 g (47.6 mmol) of trimesic acid was mixed with 25.4 mg of sodium chloride (equivalent to approximately 1000 ppm of sodium in the trimesic acid) and 5 mL of water, and the mixture was thoroughly stirred. After removing as much water as possible under reduced pressure, 28.0 g (143.2 mmol) of (trichloromethyl)benzene and 17.8 mg (0.2 mmol) of zinc oxide were added, and the suspension was heated and stirred at 145°C for 4 hours. GC analysis showed that the conversion rate of trimesic acid was 99.8%, and 94.7% of trimesic acid trichloride was produced.

[0028] [Comparative Example 2] Production of trimeciate trichloride in the presence of iron(III) chloride catalyst using (trichloromethyl)benzene 10.0 g (47.6 mmol) of trimesic acid with a sodium content of approximately 1000 ppm was prepared in the same manner as in Comparative Example 1. A suspension was added to 28.0 g (143.2 mmol) of (trichloromethyl)benzene and 32.4 mg (0.2 mmol) of anhydrous iron(III) chloride, and the mixture was heated and stirred at 145°C for 2 hours. GC analysis revealed that the conversion rate of trimesic acid was 99.7%, and 91.6% of trimesic acid trichloride was produced.

[0029] As described above, the forms of Comparative Examples 1 and 2 have a stoichiometric ratio of 3 molar equivalents of chlorinating agent required for 1 molar equivalent of trimesic acid, resulting in low volumetric efficiency. Furthermore, although Patent Document 3 states that the reaction does not proceed sufficiently and the yield of trimesic acid trichloride is insufficient when the sodium content of trimesic acid exceeds 150 ppm, the results of Comparative Examples 1 and 2, which used trimesic acid with a sodium content of approximately 1000 ppm, show that the reaction proceedings and the yield of trimesic acid trichloride are not related to the sodium content of trimesic acid. Furthermore, a comparison between Examples 1-4 and Comparative Examples 1 and 2 shows that when compound (B), which is a bis(trichloromethyl) substituted compound, is used as the chlorinating agent, it exhibits a conversion rate of trimesic acid and a production rate of trimesic acid trichloride at a level comparable to or higher than when (trichloromethyl)benzene, which is a mono(trichloromethyl) substituted compound, is used as the chlorinating agent.

[0030] [Comparative Example] Production of Trimecinate Trichloride using (Trichloromethyl)benzene in the presence of a zinc oxide catalyst - Comparison of reaction rates with and without the addition of acid chloride, a by-product of the reaction - (A) 10.0 g (47.6 mmol) of trimesic acid was sequentially mixed with 25.4 mg of sodium chloride (equivalent to approximately 1000 ppm of sodium content in trimesic acid), 28.0 g (143.2 mmol) of (trichloromethyl)benzene, and 17.8 mg (0.2 mmol) of zinc oxide, and heated and stirred at 145°C for 2 hours (Comparative Reference Example A). GC analysis revealed that the conversion rate of the raw materials was 18.5%, and the production of trimesic acid trichloride was only 14.0%, with a large amount of (trichloromethyl)benzene remaining. (B) The same procedure as in Comparative Reference Example A above was followed, except that 6.6 g (47.0 mmol) of benzoyl chloride was added beforehand at the start of the reaction, and the mixture was stirred at 145°C for 2 hours. GC analysis showed that the conversion rate of the starting material was 99.8%, and 99.5% of trimesic acid trichloride was produced. As shown above, the results of the comparative reference example demonstrate that, even in the method of producing trimecinate trichloride using chlorinating agents other than compound (B), the reaction rate can be improved by adding an acid chloride (benzoyl chloride in the comparative reference example), which is a by-product of the reaction.

[0031] [Example] Photochlorination of 1,3,5-trimethylbenzene In Example 1 (1), 120 g (1.00 mol) of 1,3,5-trimethylbenzene was used instead of 318.6 g (3.00 mol) of metaxylene, and 14.2 g (0.20 mol) of chlorine was bubbled in at 100°C per hour to perform photochlorination of 1,3,5-trimethylbenzene, and the reaction products were tracked by GC. After 6 hours, GC analysis revealed that 4.3% of the starting material 1,3,5-trimethylbenzene remained, and 44.6% of 1-chloro-2,4,6-trimethylbenzene and 8.0% of 1,3-dichloro-2,4,6-trimethylbenzene were produced as core chlorinated products, and 30.3% of 1-chloromethyl-3,5-dimethylbenzene and 4.1% of 1,3-bis(chloromethyl)-5-methylbenzene were produced as side-chain chlorinated products (where hydrogen atoms of methyl groups are substituted with chlorine). Thus, it is clear that a large amount of nuclear chloride is generated in the initial stages of the reaction, making it very difficult to obtain 1,3,5-tris(trichloromethyl)benzene in good yield.

Claims

1. A method for producing trimeciate trichloride, comprising: (I) reacting trimesic acid with the following compound (B) in the presence of at least one catalyst, which is iron(III) chloride, zinc oxide, and zinc chloride; and (II) separating the reaction product obtained in step (I) by distillation. Compound (B): 1,3-bis(trichloromethyl)benzene or 1,4-bis(trichloromethyl)benzene

2. The method for producing trimecinate trichloride according to claim 1, wherein the catalyst is iron(III) chloride.

3. A method for producing trichloride trimesinate according to claim 1, wherein the compound (B) is 1,3-bis(trichloromethyl)benzene.

4. A method for producing trichloride trimesicate according to claim 3, wherein the purity of the 1,3-bis(trichloromethyl)benzene is 98.0% or higher.

5. The method for producing trimecinate trichloride according to claim 4, wherein the 1,3-bis(trichloromethyl)benzene is 1,3-bis(trichloromethyl)benzene with a purity of 98.0% or more obtained by photochlorinating and rectifying metaxylene.

6. A method for producing trimethic acid trichloride according to any one of claims 1 to 5, wherein the reaction in step (I) contains 0.5 to 2.0 molar equivalents of isophthalic acid chloride or terephthalic acid chloride per 1 molar equivalent of trimesic acid in the reaction system.