Compound having a binaphthalene skeleton, its crystalline polymorph, and method for producing same

Abstract

To provide a method for producing a high-purity binaphthalene compound, and a high-purity binaphthalene compound and a crystalline polymorph thereof excellent in processability and productivity obtained by the production method.SOLUTION: The invention provides a compound represented by formula (2) in the figure whose purity according to high-performance liquid chromatography analysis is 93% or more. (In formula (2), X1 to X4 are halogen atoms; n1 to n2 are integers of 1 to 4; and n3 to n4 are integers of 0 to 2.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a compound having a binaphthalene skeleton and a crystal polymorph thereof, as well as a method for producing the same. [Background technology]

[0002] Resin materials such as polycarbonate, polyester, polyacrylate, polyurethane, and epoxy, which use binaphthalenes such as 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene as raw material monomers, have been attracting attention in recent years as new optical materials such as optical lenses and optical sheets, due to their excellent optical properties and heat resistance. It has also been described that a compound substituted at the 6,6'-position of 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene has even better optical properties (Patent Document 1). Patent Document 1 discloses a method for synthesizing 2,2'-bis(2-hydroxyethoxy)-6,6'-dibromo-1,1'-binaphthalene. However, the synthesis method described in the document has problems such as low purity and low yield. Another problem is that the product is a solid obtained by concentrating it with an evaporator, so its processability is poor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 043060 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a method for producing a high-purity binaphthalene compound, and to provide a high-purity binaphthalene compound and a crystalline polymorph thereof which are excellent in processability and productivity. [Means for solving the problem]

[0005] The present inventors have found that the above problems can be solved by the present invention having the following aspects.

[0006] Aspect 1 A method for producing a compound represented by the following formula (2) by reacting a compound represented by the following formula (1) with ethylene carbonate, the method comprising the following steps 1 and 2: Step 1: reacting the compound represented by formula (1) with ethylene carbonate in an amount (molar ratio) of 1:1.9 to 1:2.9 Step 2: After the reaction in step 1 is completed, an alkaline aqueous solution of 3% by weight or more is added to the reaction mixture solution obtained, and the solution is heated and stirred at a temperature of 50° C. or higher. [ka] [ka] (In formula (1) and formula (2), X 1 ~X 4 is a halogen atom, n1 and n2 are integers from 1 to 4, and n3 and n4 are integers from 0 to 2.

[0007] Aspect 2 X in formula (1) and formula (2) 1 ~X 4 A method for producing the compound according to embodiment 1, wherein Aspect 3 A method for producing a compound according to embodiment 1 or embodiment 2, wherein n1 and n2 in formula (1) and formula (2) are 1, and n3 and n4 are 0.

[0008] Aspect 4 A method for producing the compound according to any one of Aspects 1 to 3, wherein the formula (2) is the following formula (2-A): [ka]

[0009] Aspect 5 A compound represented by the following formula (2), having a purity of 93% or more as determined by high performance liquid chromatography analysis: [ka] (In formula (2), X 1 ~X 4 is a halogen atom, n1 and n2 are integers from 1 to 4, and n3 and n4 are integers from 0 to 2.

[0010] Aspect 6 X in formula (2) 1 ~X 4 The compound according to embodiment 5, wherein Aspect 7 The compound according to embodiment 5 or embodiment 6, wherein n1 and n2 in formula (2) are 1, and n3 and n4 are 0.

[0011] Aspect 8 The compound according to any one of aspects 5 to 7, wherein formula (2) is formula (2-A). [ka]

[0012] Aspect 9: A crystalline polymorph of the compound according to embodiment 8, having an endothermic peak in the range of 175 to 180° C. as measured by differential scanning calorimetry. Aspect 10 A crystalline polymorph of the compound according to embodiment 8, having peaks at diffraction angles 2θ of 16.8±0.2°, 22.6±0.2°, and 25.0±0.2° in a powder X-ray diffraction pattern using Cu-Kα radiation. Aspect 11 A crystalline polymorph of the compound according to embodiment 8, having an endothermic peak in the range of 181 to 190° C. as measured by differential scanning calorimetry. Aspect 12 A crystalline polymorph of the compound according to embodiment 8, having peaks at diffraction angles 2θ of 16.1±0.2°, 18.0±0.2°, 24.4±0.2°, 25.0±0.2° and 25.3±0.2° in a powder X-ray diffraction pattern using Cu-Kα radiation. Effect of the Invention

[0013] According to the present invention, a high-purity binaphthalene compound can be obtained in good yield, and binaphthalene compound crystals having excellent processability and productivity can be obtained. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a diagram showing a differential scanning calorimetry (DSC) curve of the crystalline polymorph A obtained in Example 1. [Diagram 2] FIG. 1 is a diagram showing the powder X-ray diffraction pattern of the crystalline polymorph A obtained in Example 1. [Diagram 3] FIG. 2 is a diagram showing a differential scanning calorimetry (DSC) curve of the crystalline polymorph B obtained in Example 2. [Figure 4] FIG. 2 is a diagram showing the powder X-ray diffraction pattern of the crystalline polymorph B obtained in Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] <<Method for producing binaphthalene compound>> (Process 1) In the present invention, a compound represented by the following formula (1) is reacted with a predetermined amount of ethylene carbonate to obtain a compound represented by the following formula (2).

[0016] [ka]

[0017] [ka]

[0018] (In formula (1) and formula (2), X 1 ~X 4 is a halogen atom, n1 and n2 are integers from 1 to 4, and n3 and n4 are integers from 0 to 2. X in formula (1) and formula (2) 1 ~X 4is a halogen atom, and particularly preferably a bromine atom. In addition, n1 to n2 in formula (1) and formula (2) are integers of 1 to 4, preferably an integer of 1 to 2, and particularly preferably 1. In addition, n3 to n4 in formula (1) and formula (2) are integers of 0 to 2, preferably an integer of 0 to 1, and particularly preferably 0. That is, it is particularly preferable that the compound represented by formula (2) is a compound represented by the following formula (2-A).

[0019] [ka]

[0020] In the present invention, the amount (molar ratio) of the compound represented by formula (1) to ethylene carbonate is 1:1.9 to 1:2.9, preferably 1:2 to 1:2.7, and more preferably 1:2.1 to 1:2.5. If the amount of ethylene carbonate used is less than 1:1.9, the reaction time may be longer. In addition, the compound represented by formula (1) remains unreacted, and the amount of by-products resulting from the reaction of 1 mole of the compound represented by formula (1) with 1 mole of ethylene carbonate increases, which is undesirable because the yield and purity decrease. If the amount of ethylene carbonate used is more than 1:2.9, the amount of by-products resulting from the reaction of 1 mole of the compound represented by formula (1) with 3 moles or more of ethylene carbonate increases, which is undesirable because the yield and purity decrease.

[0021] In the present invention, it is preferable to make a predetermined amount of non-reactive solvent coexist during the reaction. The non-reactive solvent is not particularly limited as long as it does not inhibit the reaction, and examples thereof include aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene, aliphatic hydrocarbons such as pentane, hexane, and heptane, halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene, halogenated aliphatic hydrocarbons such as dichloromethane and 1,2-dichloroethane, dimethylformamide, and dimethylsulfoxide. Toluene and dimethylformamide are preferable, and dimethylformamide is more preferable. If a predetermined amount of non-reactive solvent is not coexistent, stirring may become difficult and the reaction may not proceed or may be significantly delayed. In this case, in order to proceed with the reaction, it is necessary to increase the temperature or dilute with a large amount of solvent equal to or greater than a predetermined amount to make the reaction system into a soluble or stirrable slurry state. However, if the reaction temperature is high, the yield and purity may decrease due to an increase in by-products such as polymers, or the hue may deteriorate due to coloring.

[0022] In the present invention, the amount of the non-reactive organic solvent used in the reaction is preferably 0.1 to 4 times by weight, more preferably 0.5 to 2 times by weight, relative to the compound represented by formula (1). If the amount of the solvent used is less than 0.1 times by weight, the compound represented by formula (1) and the compound represented by formula (2) produced may be difficult to stir. If the amount of the solvent used is more than 4 times by weight, the reaction time may be delayed and the volume efficiency may be reduced, resulting in poor production efficiency and being economically disadvantageous. In addition, long-term heating operations may cause an increase in side reaction products and coloring. In the present invention, the reaction is preferably carried out using the above-mentioned predetermined amount of ethylene carbonate and a predetermined amount of non-reactive organic solvent, so that the compound represented by formula (1), which has a high melting point and low solubility in ethylene carbonate and organic solvents, can be most efficiently reacted in a solution or a stirrable slurry state, and the compound represented by formula (2) can be obtained in high yield and high purity.

[0023] In the present invention, the method for reacting the compound represented by formula (1) with a predetermined amount of ethylene carbonate is not particularly limited, but can usually be carried out by charging the compound represented by formula (1), ethylene carbonate, a solvent and a catalyst into a reaction vessel and heating and stirring in air or in an inert gas atmosphere such as nitrogen, helium, etc. The reaction can be monitored by an analytical means such as liquid chromatography.

[0024] In the present invention, the reaction temperature is not particularly limited, but is usually 150° C. or less, preferably 140 to 40° C., and more preferably 130 to 70° C. If the reaction temperature is too high, it may cause a decrease in yield and a deterioration in color due to an increase in by-products. If the reaction temperature is too low, the reaction may not proceed quickly.

[0025] The catalyst used in the present invention may be either an alkali catalyst or an acid catalyst, but an alkali catalyst is preferred because the reaction proceeds quickly and impurities are reduced. Examples of alkali catalysts include potassium hydroxide, sodium hydroxide, barium hydroxide, magnesium oxide, sodium carbonate, and potassium carbonate. Among them, potassium hydroxide, sodium hydroxide, and potassium carbonate are preferred. The use of an acid catalyst is not particularly limited, and examples thereof include sulfuric acid, paratoluenesulfonic acid, and methanesulfonic acid. The amount of catalyst used is not particularly limited, but is usually preferably 0.01 to 0.5 mol, more preferably 0.05 to 0.2 mol, per mol of the compound represented by formula (1). If the amount of catalyst is small, the reaction may not proceed or may be delayed. If the amount of catalyst is large, the yield and purity may decrease due to an increase in by-products, and coloring may occur.

[0026] (Process 2) In the present invention, a process is carried out in which an aqueous alkali solution having a concentration of 3% by weight or more is added to a reaction mixture solution containing a compound represented by formula (2) obtained by reacting a compound represented by formula (1) with a predetermined amount of ethylene carbonate, and the solution is heated and stirred at a temperature of 50°C or higher (hereinafter referred to as an alkali purification process).

[0027] In the present invention, the concentration of the alkaline aqueous solution added to the reaction mixture solution containing the compound represented by formula (2) is 3% by weight or more, preferably 6% by weight or more, and more preferably 8% by weight or more. By adding an alkaline aqueous solution with a concentration of 3% by weight or more and heating and stirring at a temperature of 50°C or more, it is possible to remove by-products resulting from the reaction of 1 mole of the compound represented by formula (1) with 3 moles or more of ethylene carbonate. In addition, since colored components can be removed into the alkaline aqueous solution, it is possible to obtain a compound represented by formula (2) with high purity and little coloring. If the concentration of the alkaline aqueous solution is lower than 3% by weight, it is not preferable because by-products and colored components cannot be efficiently removed. The alkaline concentration is not particularly limited as long as it is 3% by weight or more, but from the viewpoint of the solubility of the alkali and ease of handling, a concentration of preferably 50% by weight or less, more preferably 30% by weight or less, and even more preferably 15% by weight or less is preferable.

[0028] The temperature at which the aqueous alkaline solution is heated and stirred is 50°C or higher, preferably 60°C or higher, more preferably 80°C or higher, and is preferably a temperature below the boiling point of the solvent used, more preferably 130°C or lower. Temperatures lower than 50°C are not preferred because by-products cannot be removed or cannot be removed efficiently. Temperatures higher than 130°C are not preferred because impurities increase, the purity decreases, and the hue deteriorates. The stirring time is not particularly limited, but is preferably 0.5 to 10 hours, more preferably 1 to 9 hours, and even more preferably 2 to 8 hours.

[0029] The alkali used in the alkaline aqueous solution of the present invention is not particularly limited, but includes lithium hydroxide, sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, calcium hydroxide, barium hydroxide, sodium carbonate, potassium carbonate, etc. Sodium hydroxide and potassium hydroxide are preferred. The amount of alkali used is not particularly limited, but in order to efficiently remove by-products and coloring components, it is usually preferably 0.1 to 20 mol, more preferably 0.2 to 10 mol, and even more preferably 0.3 to 5 mol per mol of the compound represented by formula (1). If the amount of alkali is less than 0.1 mol, by-products may not be efficiently removed. Also, coloring components may not be efficiently removed, which is not preferred. If the amount of alkali is more than 20 mol, the purity may decrease and the hue may deteriorate, which is not preferred.

[0030] In the present invention, the alkali purification step may be carried out by adding an aqueous alkali solution to a reaction mixture solution containing a compound represented by formula (2) and heating and stirring, or by diluting the reaction mixture solution with an organic solvent and then adding an aqueous alkali solution and heating and stirring. Usually, the step is carried out after dilution with an organic solvent. The organic solvent to be used for dilution is not particularly limited, but examples thereof include aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene, aliphatic hydrocarbons such as pentane, hexane, and heptane, halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene, dimethylformamide, and dimethylsulfoxide. Toluene and dimethylformamide are preferred, and dimethylformamide is more preferred. After the alkali purification operation, the aqueous alkali solution can be separated and removed. In addition, other purification operations such as water washing, adsorption treatment, and filtration may be added after the alkali purification operation.

[0031] Generally, the compound represented by formula (2) is more difficult to crystallize as the amount of by-products to which 3 moles or more of ethylene carbonate are added increases, but in the present invention, the amount of these by-products is small, so the compound can be easily crystallized, and compared with the solids obtained by distilling off the conventionally known solvent and concentrating to dryness, the crystals are easy to handle and can be easily extracted. In addition, the crystals of the compound represented by formula (2) can be obtained with good hue and purity.

[0032] In the present invention, the compound represented by formula (2) may be purified by crystallization to further increase its purity. The organic solvent used for crystallization purification is not particularly limited, but may include aromatic hydrocarbons such as toluene, xylene, and mesitylene, aliphatic hydrocarbons such as hexane and heptane, halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene, alcohols such as methanol, ethanol, propanol, and butanol, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, esters such as ethyl acetate and butyl acetate, dimethylformamide, and dimethyl sulfoxide. These organic solvents may be used alone or in combination of two or more kinds. These solvents may be newly added, or the solvent used in the alkali purification step may be used as it is without being newly added. The amount of the organic solvent used is not particularly limited, but from the viewpoint of economy, it is usually 1 weight or more, preferably 1 to 50 weight times, and more preferably about 3 to 20 weight times, relative to the compound represented by formula (2).

[0033] Crystallization purification can be carried out by a general method and is not particularly limited. Usually, the mixture to be crystallized is heated to a temperature at which the crystals in the mixture are dissolved, for example, 60°C or higher, preferably 80°C or higher, and then the solution is cooled to an appropriate temperature, for example, -10 to 30°C, to obtain the target crystals. The precipitated crystals are collected by filtration or the like, and can be isolated by washing and drying as necessary. If necessary, the isolated crystals may be purified. Examples of purification methods include recrystallization (recrystallization) and impurity removal treatment using an adsorbent such as activated carbon.

[0034] <Binaphthalene compounds> In the present invention, the purity of the compound represented by formula (2) is 93% or more, preferably 95% or more, and more preferably 97% or more. Regarding the purity in the present invention, % is an area percentage value excluding the solvent in high performance liquid chromatography (HPLC) measurement.

[0035] In the present invention, X in formula (2) 1 ~X 4 is a halogen atom, and particularly preferably a bromine atom. In addition, n1 and n2 in formula (2) are integers of 1 to 4, preferably an integer of 1 to 2, and particularly preferably 1. In addition, n3 and n4 in formula (2) are integers of 0 to 2, preferably an integer of 0 to 1, and particularly preferably 0. In other words, it is particularly preferable that the compound represented by formula (2) is a compound represented by the above formula (2-A).

[0036] <Polymorphic forms of binaphthalene compounds> The crystal of the compound represented by formula (2-A) obtained in the present invention preferably has an endothermic peak in the range of 175 to 180°C by differential scanning calorimetry. This is referred to as crystalline polymorph A in the present application. The crystalline polymorph A preferably has characteristic peaks at diffraction angles 2θ of 16.8±0.2°, 22.6±0.2°, and 25.0±0.2° in a powder X-ray diffraction pattern using Cu-Kα radiation. In addition, the diffraction angle 2θ preferably has a maximum peak at 22.6±0.2°. In addition, each diffraction angle 2θ is in the range of ±0.2°, more preferably in the range of ±0.1°. The crystalline polymorph A of the present invention is a crystal that is excellent in handleability and has good hue and purity compared to a solid obtained by distilling off a conventionally known solvent and concentrating and drying.

[0037] The crystal of the compound represented by formula (2-A) obtained in the present invention preferably has an endothermic peak in the range of 181 to 190°C by differential scanning calorimetry. This is referred to as crystalline polymorph B in the present application. The crystalline polymorph B preferably has characteristic peaks at diffraction angles 2θ of 16.1±0.2°, 18.0±0.2°, 24.4±0.2°, 25.0±0.2°, and 25.3±0.2° in a powder X-ray diffraction pattern using Cu-Kα radiation. The diffraction angle 2θ preferably has a maximum peak at 24.4±0.2°. Each diffraction angle 2θ is in the range of ±0.2°, more preferably ±0.1°. The crystalline polymorph B of the present invention is a crystal that is excellent in handleability and has good hue and purity compared to a solid obtained by distilling off a conventionally known solvent and concentrating and drying.

[0038] The above-mentioned crystalline polymorph A and crystalline polymorph B can be produced by using different solvents during crystallization. That is, crystalline polymorph A can be produced by dissolving the compound represented by formula (2-A) in dimethylformamide and then crystallizing it, and crystalline polymorph B can be produced by dissolving the compound represented by formula (2-A) in ethyl acetate, methyl ethyl ketone, toluene, etc. and then crystallizing it. In addition, crystalline polymorph B can also be produced by heating crystalline polymorph A at 60 to 170 ° C. and causing crystal transition.

[0039] In addition, the crystal of the compound represented by formula (2-A) of the present invention is a racemate, but may contain a large amount of any one of the optically active isomers within the range in which the above-mentioned effects of the present invention are exhibited. The ratio of R-form to S-form is preferably R-form / S-form=45 / 55 to 55 / 45. EXAMPLES

[0040] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples as long as it does not depart from the gist of the present invention. In the examples, various measurements were carried out as follows.

[0041] (1) High performance liquid chromatography (HPLC) measurement Measurement was performed using a Hitachi high performance liquid chromatograph L-2350 under the measurement conditions shown in Table 1. In the examples, unless otherwise specified, % is an area percentage value corrected by excluding the solvent in HPLC.

[0042] [Table 1]

[0043] (2) Differential scanning calorimetry (DSC) The measurements were performed using a Discovery DSC25 manufactured by TA Instruments under a nitrogen flow at a heating rate of 20° C. / min.

[0044] (3) Powder X-ray diffraction measurement Measurements were performed using a RIGAKU RINT TTR III under the following measurement conditions. X-ray source: Cu-Kα, output: 50kV-300mA (15kW) DS:1 / 2°, HS:10mm, SS:1 / 2°, RS:0.15°, Step:0.01°, Scan speed: 1.0° / min

[0045] [Example 1] 200g (0.450 mol) of 6,6'-dibromo-1,1'-bi-2-naphthol (hereinafter sometimes abbreviated as BN-6Br), 91.21g (1.036 mol) of ethylene carbonate, 6.47g of potassium carbonate, and 200ml of dimethylformamide were charged into a flask equipped with a stirrer, a condenser, and a thermometer, and reacted at 120°C for 7 hours. HPLC analysis showed that BN-6Br was 0.1% and 2,2'-bis(2-hydroxyethoxy)-6,6'-dibromo-1,1'-binaphthalene (hereinafter sometimes abbreviated as BN2EO-6Br) was 95.7%. The reaction mixture was diluted with 280 ml of dimethylformamide, and then 50 ml of 10% by weight aqueous sodium hydroxide was added and stirred at 110°C for 4 hours. The reaction solution was then dropped into 2 L of distilled water while stirring to crystallize BN2EO-6Br. The crystals were collected and washed three times with 2 L of distilled water. The collected crystals were vacuum dried at 90°C for 7 hours to obtain 228 g of BN2EO-6Br crystals (yield: 95%, purity: 98.0%, endothermic peak by DSC: 177°C). The DSC chart is shown in Figure 1, the powder X-ray measurement chart is shown in Figure 2, and the main peaks of the powder X-ray measurement are shown in Table 2.

[0046] [Table 2]

[0047] [Example 2] A flask equipped with a stirrer, a cooler, and a thermometer was charged with 80g (0.180 mol) of BN-6Br, 41.24g (0.468 mol) of ethylene carbonate, 1.69g of potassium carbonate, and 185ml of toluene, and reacted at 110°C for 18 hours. Measurement by HPLC revealed that BN-6Br was 0.1% and BN2EO-6Br was 85.4%. The resulting reaction mixture was diluted with 185ml of toluene, and then 200ml of 10% by weight aqueous sodium hydroxide solution was added and stirred at 85°C for 5 hours. After stirring, the reaction solution was concentrated, 150ml of ethyl acetate was added, and the mixture was washed three times with 500ml of distilled water. Then, 150ml of hexane was added to the ethyl acetate solution of BN2EO-6Br to crystallize BN2EO-6Br. The collected crystals were vacuum dried at 90°C for 7 hours, and 60g of BN2EO-6Br crystals were obtained. (Yield: 62%, purity: 97.9%, endothermic peak by DSC: 185°C). The DSC chart is shown in FIG. 3, the powder X-ray measurement chart is shown in FIG. 4, and the main peaks of the powder X-ray measurement are shown in Table 3.

[0048] [Table 3]

[0049] [Comparative Example 1] A method described in Example 2.1 of Patent Document 1 (which involves reacting the compound represented by formula (1) with ethylene carbonate in a molar ratio of 1:3, and which does not satisfy claim 1 of the present invention because it does not include a step of adding an alkaline aqueous solution of 3% by weight or more and heating and stirring at a temperature of 50°C or more) was used to obtain a solid of BN2EO-6Br (yield: 20%, purity: 92.2%).

[0050] [Comparative Example 2] A solid of BN2EO-6Br was obtained (yield: 84%, purity: 90.0%) by the method described in Example 3.2 of Patent Document 1 (which does not satisfy claim 1 of the present invention because ethylene carbonate is not used).

[0051] [Comparative Example 3] A solid of BN2EO-6Br was obtained (yield: 90%, purity: 91.3%) by the method described in Comparative Example 3.4 of Patent Document 1 (which does not satisfy claim 1 of the present invention because ethylene carbonate is not used). [Industrial Applicability]

[0052] The binaphthalene compound of the present invention has high purity and is a crystalline substance, and therefore has excellent processability and productivity. Furthermore, resins made from derivatives of such binaphthalene compounds as raw materials have excellent properties such as a high refractive index, heat resistance, and low birefringence, and therefore are suitably used as raw materials for resins.

Claims

1. A crystalline polymorph of the compound represented by the following formula (2-A), which has an endothermic peak in the range of 175 to 180°C by differential scanning calorimetry, a purity of 97% or more by high performance liquid chromatography analysis, and peaks at diffraction angles 2θ of 16.8±0.2°, 22.6±0.2°, and 25.0±0.2° in a powder X-ray diffraction pattern using Cu-Kα radiation: 【Chemistry 1】

2. A crystalline polymorph of the compound represented by the following formula (2-A), which has an endothermic peak in the range of 181 to 190°C by differential scanning calorimetry, a purity of 97% or more by high performance liquid chromatography analysis, and peaks at diffraction angles 2θ of 16.1±0.2°, 18.0±0.2°, 24.4±0.2°, 25.0±0.2°, and 25.3±0.2° in a powder X-ray diffraction pattern using Cu-Kα rays: 【Chemistry 2】

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