Crystal of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl] fluorene and method for producing same

Abstract

The present invention addresses the problem of providing a form of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl] fluorene (compound A), and a method for producing the form of the compound A, that can be implemented as an industrial production method and with which it is possible to efficiently produce the compound A. As a means for solving the problem, provided is a crystal of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl] fluorene, the crystal having diffraction peaks at diffraction angles 2θ of 10.9° ± 0.2°, 15.1° ± 0.2°, and 19.7° ± 0.2° in a powder X-ray diffraction peak pattern by Cu-Kα radiation.

Description

Crystals of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene and a method for producing the same

[0001] The present invention relates to novel crystals of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene and a method for producing the same.

[0002] Fluorene derivatives are promising as raw materials for producing polymers with excellent heat resistance, transparency, and a high refractive index. In particular, they have been expected in recent years as raw material for materials such as optical lenses, films, plastic optical fibers, optical disk substrates, heat-resistant resins, and engineering plastics. Therefore, in order to further enhance the functionality of the materials, the development of novel fluorene derivatives and their production methods is desired.

[0003] Fluorene derivatives having a structure in which phenanthrene is bonded to fluorene, and as a specific example, 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene (hereinafter sometimes referred to as Compound A) is known to be suitable as a monomer for forming a resin constituting an optical member, typified by optical lenses and optical films (for example, Patent Document 1). Patent Document 1 lists separation means such as filtration, concentration, extraction, crystallization, recrystallization, reprecipitation, activated carbon treatment or a metal removal treatment similar thereto, and column chromatography. Specifically, a method of dissolving Compound A in toluene and then adding hexane for recrystallization is described.

[0004] International Publication No. 2022 / 038997

[0005] The present inventors investigated a method for isolating 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene (compound A) based on the method described in Patent Document 1. As described in Comparative Example 1 below, it became clear that compound A has extremely low solubility in toluene, making it difficult to obtain crystals of compound A by crystallization, or that the amount of compound A obtained per unit volume of the crystallization solution is extremely small, making it difficult to implement as an industrial production method. In view of this, the object of the present invention is to provide a form of compound A and a method for producing the same that can be implemented as an industrial production method and can produce compound A efficiently.

[0006] As a result of diligent research to solve the above problems, the inventors of the present invention have found a method to efficiently and highly purely obtain crystals of compound A by performing a crystallization step using a specific solvent when separating and purifying 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene, and have completed the present invention.

[0007] The present invention is as follows: 1. A crystal of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene having diffraction peaks at diffraction angles 2θ of 10.9±0.2°, 15.1±0.2°, and 19.7±0.2° in the powder X-ray diffraction peak pattern using Cu-Kα rays. 2. The crystal according to 1, wherein the peak top temperature of the endothermic peak determined by differential scanning calorimetry analysis is in the range of 203 to 213°C. 3. A method for producing the crystal according to 1, comprising a crystallization step of precipitating the crystal from a crystallization solution containing 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene, an aliphatic ketone solvent having 3 to 6 carbon atoms, and toluene. 4. A method for producing the crystal according to 3, comprising a crystallization step of precipitating the crystal by evaporation crystallization, wherein the aliphatic ketone solvent having 3 to 6 carbon atoms is evaporated from the crystallization solution.

[0008] The crystals produced by the present invention exhibit excellent effects, including the ability to isolate and purify compound A in high yield, as well as superior color. Furthermore, the crystal production method of the present invention allows for the efficient production of high-purity 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene crystals.

[0009] The crystal of compound A obtained in Example 1 １ This is a chart of the 1H-NMR analysis. The crystals of compound A obtained in Example 1 １３ This figure shows the chart of the 13C-NMR analysis. This figure shows the chart of the powder X-ray diffraction (PXRD) analysis of the compound A crystal obtained in Example 1. This figure shows the chart of the differential scanning calorimetry (DSC) analysis of the compound A crystal obtained in Example 1. This figure shows the chart of the differential thermal and thermogravimetric (TG / DTA) simultaneous measurement thermal analysis of the compound A crystal obtained in Example 1. This figure shows the chart of the powder X-ray diffraction (PXRD) analysis of the compound A crystal obtained in Example 2. This figure shows the chart of the differential scanning calorimetry (DSC) analysis of the compound A crystal obtained in Example 2. This figure shows the differential thermal and thermogravimetric (TG / DTA) simultaneous measurement thermal analysis of the compound A crystal obtained in Example 2. This figure shows the powder X-ray diffraction (PXRD) analysis of the compound A crystal obtained in Example 3. This figure shows the differential scanning calorimetry (DSC) analysis of the compound A crystal obtained in Example 3. This figure shows the differential thermal and thermogravimetric (TG / DTA) simultaneous thermal analysis chart of the compound A crystal obtained in Example 3. This figure shows the powder X-ray diffraction (PXRD) analysis chart of the compound A crystal obtained in Example 4. This figure shows the differential scanning calorimetry (DSC) analysis chart of the compound A crystal obtained in Example 4. This figure shows the differential thermal and thermogravimetric (TG / DTA) simultaneous thermal analysis chart of the compound A crystal obtained in Example 4.

[0010] The present invention will be described in detail below. <Crystals of Compound A of the present invention> The crystals of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene (compound A) of the present invention have diffraction peaks at diffraction angles 2θ of 10.9±0.2°, 15.1±0.2°, and 19.7±0.2° in the powder X-ray diffraction peak pattern using Cu-Kα rays. It is more preferable that, in addition to the above peaks, the powder X-ray diffraction peak pattern using Cu-Kα rays also has diffraction peaks at diffraction angles 2θ of 17.8±0.2°, 20.8±0.2°, and 21.8±0.2°. Furthermore, the relative intensity of the peaks obtained by powder X-ray diffraction using Cu-Kα rays is preferably 10 or higher, more preferably 15 or higher, and even more preferably 25 or higher, with the peak with the highest intensity as the reference (relative intensity of 100). However, the relative intensity may fluctuate depending on the measuring device and conditions, and in the case of mixtures with other crystals. Therefore, the crystalline phase can be identified based on the analysis method of normal powder X-ray diffraction analysis. The method for performing powder X-ray diffraction (PXRD) analysis in the present invention is the method according to the powder X-ray diffraction (PXRD) analysis method in the examples described later. The crystals of compound A of the present invention preferably have a peak top temperature of the endothermic peak obtained by differential scanning calorimetry analysis in the range of 203 to 213°C. The peak top temperature is more preferably in the range of 204 to 212°C, and particularly preferably in the range of 205 to 211°C. Furthermore, in this case, it is preferable that the onset temperature of the endothermic peak obtained by differential scanning calorimetry analysis is in the range of 195 to 210°C. The onset temperature is more preferably in the range of 197 to 207°C, even more preferably in the range of 198 to 206°C, and particularly preferably in the range of 199 to 205°C. The differential scanning calorimetry (DSC) method in this invention is the same as the differential scanning calorimetry method in the analytical method of the examples described later.The purity of the crystals of compound A of the present invention is preferably such that the ratio of the peak area of ​​compound A to the peak area of ​​all components detected at a wavelength of 280 nm in high-performance liquid chromatography (HPLC) analysis is 95.0% or higher, more preferably 97.0% or higher, even more preferably 98.0% or higher, and particularly preferably 99.0% or higher. The method for HPLC analysis of the purity of the crystals of the present invention is the same as the HPLC analysis method in the examples described later. The hue of the crystals of compound A of the present invention is preferably such that the Hazen unit color number (APHA) when used in a 10% by weight acetone solution is 200 or less, more preferably 180 or less, even more preferably 150 or less, and particularly preferably 100 or less. Since a smaller Hazen unit color number (APHA) value is preferable, there is no limit to the lower limit of this value range, but it may be 1 or higher. The upper and lower limits of these ranges can be arbitrarily combined. The crystals of compound A of the present invention preferably have a weight loss rate of 10% by weight or less at 300°C as determined by thermogravimetric analysis. This weight loss rate is more preferably 8.0% by weight or less, even more preferably 7.5% by weight or less, and particularly preferably 7.0% by weight or less. There is no lower limit to this range, as a lower content is preferable, but it may be 1.0% by weight or more, 3.0% by weight or more, or 5.0% by weight or more. The upper and lower limits of these ranges can be arbitrarily combined. The crystals of compound A may contain organic solvents, raw materials, water, etc., used in the manufacturing process. Organic solvents may include, for example, aliphatic ketone solvents with 3 to 6 carbon atoms used in the crystallization process, toluene, and organic solvents used in earlier processes. The method for performing thermogravimetric analysis is the differential thermal and thermogravimetric (TG / DTA) simultaneous measurement thermal analysis method described in the examples below. The crystals of compound A of the present invention preferably have a sodium content of 5.0 ppm or less, more preferably 3.0 ppm or less, even more preferably 1.0 ppm or less, and particularly preferably 0.5 ppm or less, when the sodium content of the crystals is analyzed.When the potassium content of the crystals of compound A of the present invention is analyzed, it is preferably 5.0 ppm or less, more preferably 3.0 ppm or less, even more preferably 1.0 ppm or less, and particularly preferably 0.5 ppm or less. When the iron content of the crystals of compound A of the present invention is analyzed, it is preferably 5.0 ppm or less, more preferably 3.0 ppm or less, even more preferably 1.0 ppm or less, and particularly preferably 0.5 ppm or less. When the copper content of the crystals of compound A of the present invention is analyzed, it is preferably 5.0 ppm or less, more preferably 3.0 ppm or less, even more preferably 1.0 ppm or less, and particularly preferably 0.5 ppm or less. The method for analyzing the content of these metals is according to the analytical method of the examples described later.

[0011] The 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene (compound A) according to the present invention is a compound having the following chemical structure.

[0012] (Method for producing Compound A) The method for producing 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene (Compound A) according to the present invention is not particularly limited and can be produced by conventionally known methods. For example, two equivalents of 9-phenantrol and one equivalent of fluorenone undergo a dehydration condensation reaction to produce one equivalent of 9,9-bis[9-hydroxy-3-phenanthryl]fluorene together with one equivalent of water. Furthermore, a method can be described in which 9,9-bis[9-hydroxy-3-phenanthryl]fluorene is reacted with a hydroxyethoxylation agent to produce Compound A. The reaction for producing Compound A when ethylene carbonate is used as the hydroxyethoxylation agent is shown in the following reaction formula. There are no restrictions on the compound A used in the crystallization step in the crystal manufacturing method of the present invention, which will be described later. For example, compound A obtained by the above-described reaction, compound A obtained by separation operations such as concentration, reprecipitation, and column separation from a reaction solution containing compound A, crystals of compound A of the present invention, and crystals other than crystals of compound A of the present invention can be used.

[0013] <Method for producing crystals of compound A of the present invention> The method for producing crystals of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene (compound A) of the present invention is characterized by comprising a crystallization step of precipitating the crystals from a crystallization solution containing 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene, an aliphatic ketone solvent having 3 to 6 carbon atoms, and toluene.

[0014] (Crystallization Solvent) The aliphatic ketone solvents having 3 to 6 carbon atoms used in the crystallization process include linear aliphatic ketone solvents having 3 to 6 carbon atoms and cyclic aliphatic ketone solvents having 3 to 6 carbon atoms. Among these, from the viewpoint of ease of operation in the industrial crystallization process, linear aliphatic ketone solvents having 3 to 6 carbon atoms or cyclic aliphatic ketone solvents having 6 carbon atoms are preferred, linear aliphatic ketone solvents having 3 to 6 carbon atoms are more preferred, and linear aliphatic ketone solvents having 3 or 4 carbon atoms, such as acetone or methyl ethyl ketone, are even more preferred, with acetone being particularly preferred. Specific examples of aliphatic ketone solvents to be used include acetone, methyl ethyl ketone, diethyl ketone, 2-pentanone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone. At least one of these is preferred, at least one selected from acetone, methyl ethyl ketone, diethyl ketone, 2-pentanone, methyl isobutyl ketone, and cyclohexanone is more preferred, at least one selected from acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone is even more preferred, and at least one selected from acetone and methyl ethyl ketone is particularly preferred. Two or more types of aliphatic ketone solvents may be used, but it is preferable to use one type alone. In other words, it is preferable to use one solvent selected from acetone, methyl ethyl ketone, diethyl ketone, 2-pentanone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; it is more preferable to use one solvent selected from acetone, methyl ethyl ketone, diethyl ketone, 2-pentanone, methyl isobutyl ketone, and cyclohexanone; it is even more preferable to use one solvent selected from acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and it is particularly preferable to use acetone or methyl ethyl ketone as the solvent.The amount of aliphatic ketone solvent having 3 to 6 carbon atoms used relative to compound A can be appropriately adjusted in view of the crystallization process conditions and the solubility of the aliphatic ketone solvent used, but is preferably in the range of 1.0 to 35.0 times by weight, more preferably in the range of 1.0 to 15.0 times by weight, even more preferably in the range of 1.2 to 10.0 times by weight, and particularly preferably in the range of 1.2 to 4.0 times by weight. The amount of toluene used relative to the amount of aliphatic ketone solvent having 3 to 6 carbon atoms can be appropriately adjusted in view of the crystallization process conditions and the solubility of the aliphatic ketone solvent having 3 to 6 carbon atoms used and toluene in compound A, but is preferably in the range of 1.0 to 200.0 times by weight, more preferably in the range of 1.0 to 150.0 times by weight, even more preferably in the range of 1.0 to 50.0 times by weight, even more preferably in the range of 1.0 to 15.0 times by weight, and particularly preferably in the range of 1.0 to 5.0 times by weight. There are no restrictions on the method for preparing such crystallization solutions, but it is preferable to prepare a solution of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene with an aliphatic ketone solvent having 3 to 6 carbon atoms, and then add toluene. Toluene acts as a poor solvent, allowing for poor solvent-added crystallization in which crystals are precipitated. In addition, in the crystallization step of the crystal production method of the present invention, a small amount of solvent other than the above-mentioned organic solvent may be included, as long as it does not impair the effects of the present invention. A small amount means, for example, the amount of organic solvent or water that remains after the step to remove them, which is a step prior to the crystallization step, such as the reaction step or water washing step described above.

[0015] (Crystallization Method) In the crystal production method of the present invention, from the viewpoint of yielding compound A, it is preferable to further lower the temperature of the crystallization solution. The upper limit of the temperature of the crystallization solution is 1°C lower than the boiling point of the crystallization solvent used, and the lower limit of the temperature depends on the aliphatic ketone solvent with 3 to 6 carbon atoms and toluene used. The crystallization solution is heated to 15°C, preferably 20°C, more preferably 30°C, and particularly preferably 45°C, within the range from the upper limit to the lower limit. After that, the crystallization solution is cooled to a range of 0 to 40°C, preferably 10 to 40°C, more preferably 15 to 35°C, and even more preferably 15 to 30°C. Specifically, the temperature 1°C lower than the boiling point of the crystallization solvent used in the present invention means, for example, 55°C when using acetone with a boiling point of 56°C (at 1 atmosphere). This refers to the temperature based on the boiling point (at 1 atmosphere) corresponding to the weight ratio of the aliphatic ketone solvent with 3 to 6 carbon atoms used and toluene, or, if two or more types of aliphatic ketone solvents with 3 to 6 carbon atoms are used, their types and weight ratios.

[0016] The crystallization step in the crystal production method of the present invention may preferably include a crystallization step in which aliphatic ketone solvent having 3 to 6 carbon atoms is evaporated from the crystallization solution to precipitate crystals by evaporation crystallization. In this evaporation crystallization, the content of aliphatic ketone solvent having 3 to 6 carbon atoms in the crystallization solution after evaporation can be appropriately adjusted in view of the ease of operation of the evaporation operation and the ease of crystal precipitation, depending on the amount of toluene contained in the crystallization solution, but is preferably in the range of 0.01 to 0.7 times the weight of compound A, more preferably in the range of 0.01 to 0.5 times the weight, and particularly preferably in the range of 0.01 to 0.3 times the weight.

[0017] The crystals of compound A obtained by the crystallization process can be separated from the crystallization solution by filtration and recovered. During filtration, the filtered crystals can be washed with an organic solvent, such as an aliphatic ketone solvent with 3 to 6 carbon atoms or toluene used in the crystallization process, or an aromatic hydrocarbon organic solvent with 7 to 9 carbon atoms, including xylene. The obtained crystals can be dried to remove the solvent used. The drying operation can preferably be carried out at a temperature in the range of 30 to 100°C, more preferably in the range of 60 to 95°C, and even more preferably in the range of 70 to 90°C. Drying can be carried out under atmospheric pressure or reduced pressure, but in industrial operations, reduced pressure of about 10 kPa is preferred, more preferably about 5 kPa, and even more preferably about 1.5 kPa, as these reduced pressure conditions are preferable because they allow for more efficient removal of the solvent used.

[0018] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples. <Analysis Method> 1. High-performance liquid chromatography (HPLC) analysis (Apparatus and conditions) High-performance liquid chromatography analyzer: Prominence UFLC / manufactured by Shimadzu Corporation Pump: LC-20AD Column oven: CTO-20A Detector: SPD-20A Column: HALO C18 column 3.0 × 75 mm Oven temperature: 50℃ Flow rate: 0.7 mL / min. Mobile phase: (A) 0.2 vol% aqueous acetic acid solution, (B) methanol gradient Conditions: (B) vol% (time from start of analysis) 0-7 min.: 50 → 70%, 7-13 min.: 70%, 13-20 min.: 70 → 100%, 20-23 min. : 100% Sample injection volume: 5 μL Analytical sample: 50 mg / 50 mL of crystalline compound A (solvent: methanol) Detection wavelength: 280 nm

[0019] 2. Differential Scanning Calorimetry (DSC) (Analysis Method) 2-3 mg of crystals were collected in an aluminum sample container, the lid was attached, and the container was pressed to prepare a sample. The obtained sample was analyzed using the following equipment and conditions. (Equipment and Conditions) Equipment: DSC7020 / Hitachi High-Tech Science Co., Ltd. Heating rate: 10°C / min. Measurement temperature range: 30-300°C Measurement atmosphere: 50 mL / min. nitrogen

[0020] 3. Nuclear Magnetic Resonance (NMR) Analysis (Instrument and Conditions) Instrument: Fourier Transform Nuclear Magnetic Resonance AVANCE III HD 400 / BRUKER Solvent: Deuterated Chloroform (CDCl ３ ) measurement: １ H-NMR and １３ Measure the C-NMR spectrum.

[0021] 4. Powder X-ray diffraction (PXRD) analysis: The crystals were thoroughly ground in a mortar and packed into the measurement cell. The obtained sample was analyzed using the following equipment and conditions. (Equipment and conditions) Equipment: SmartLab / Rigaku Corporation X-ray source: CuKα Scan axis: 2θ / θ Mode: Continuous Measurement range: 2θ = 5° to 90° Step: 0.02° Speed ​​measurement time: 2θ = 10° / min. Output: 40kV, 30mA

[0022] 5. Analysis of Metal Content (Analysis Method) After dry ashing, acid dissolution was performed, and the sodium and potassium content was analyzed by atomic absorption spectrometry, while the iron and copper content was analyzed by inductively coupled plasma mass spectrometry.

[0023] 6. Moisture content measurement (Equipment and conditions) Equipment: Karl Fischer moisture meter. Moisture content was measured based on the standard Karl Fischer titration method.

[0024] 7. Hue Evaluation (Equipment and Conditions) Equipment: TZ 6000 / Manufactured by Nippon Denshoku Industries Co., Ltd. For the compound to be measured, an acetone solution (10% by weight) was prepared and the hue was measured.

[0025] 8. Headspace Gas Chromatography (HS-GC) (1) HS-GC analyzer and conditions Gas chromatography system: GC-2010 Plus / Shimadzu Corporation Column: InertCap-160m x 0.25mmΦ / GL Sciences Inc. Film thickness: 0.25μm Detector: FID Vaporization chamber temperature: 300℃ Detector temperature: 310℃ Column temperature: 40℃ Column heating conditions (holding time): 40℃ (10 min.) → 20℃ / min. → 300℃ (5 min.) Makeup gas (nitrogen) flow rate: 30.0 mL / min. Hydrogen flow rate: 40.0 mL / min. Air flow rate: 400.0 mL / min. Carrier gas: Nitrogen Pressure: 118 kPa Column flow rate: 0.92 mL / min. Linear velocity: 19.9 cm / sec. Total flow rate: 8.5 mL / min. Split ratio: 5 HS sampler apparatus: Turbo Matrix HS40 / PerkinElmer Co., Ltd. HS carrier gas pressure: 154.0 kPa Oven temperature: 100°C Needle temperature: 105°C Transfer temperature: 105°C Holding time: 20 min. Pressurization time: 3 min. Withdrawal time: 0.5 min. Injection time: 0.05 min. (2) Measurement of the solvent content of the crystals of compound A Samples of multiple N-methylpyrrolidone (NMP) solutions with different concentrations were prepared for the solvent to be quantified and analyzed using the apparatus and conditions described in (1) above. A calibration curve was created from the relationship between the sample concentration of the component to be quantified and the peak area detected by HS-GC analysis. 0.5 g of crystals was dissolved in 9.5 g of NMP, and 3.0 g of the resulting sample solution was analyzed using the apparatus and conditions described in (1) above. The amount of solvent contained in the crystal was calculated using a calibration curve.

[0026] 9. Thermal Analysis by Simultaneous Differential Thermal and Thermogravimetric (TG / DTA) Measurement (Analysis Method) 10 mg of crystals was weighed into an aluminum sample container and analyzed using the following apparatus and conditions. (Apparatus and Conditions) Apparatus: DTG-60A / Shimadzu Corporation Heating rate: 10°C / min. Measurement temperature range: 30 to 300°C Measurement atmosphere: Open, 50 mL / min of nitrogen

[0027] <Comparative Example 1: Further testing of the method described in Patent Document 1> 0.2 g of compound A and 20.0 g of toluene were added to a test tube and stirred for 1 hour while heating at 70°C, confirming that compound A was completely dissolved. The concentration of compound A at this time was 0.98% by weight. Subsequently, 0.4 g of compound A was added to the same test tube and stirred for 1 hour while heating under reflux at 130°C, confirming that compound A was completely dissolved. The concentration of compound A at this time was 2.96% by weight.

[0028] From the results of Comparative Example 1, it became clear that when compound A is completely dissolved in toluene alone, even when heated under reflux at a high temperature of 130°C, exceeding the boiling point of toluene (110°C), the solubility of compound A remains low. Since the concentration of compound A in the crystallization solution using toluene as the solvent is dilute, it is considered that crystal precipitation is difficult, or even if crystals do precipitate, the amount of compound A obtainable relative to the weight of the crystallization solution is very small. Patent Document 1 describes the recrystallization operation of compound A by mixing hexane with the toluene solution. Adding hexane to the crystallization solution of compound A and toluene under reflux to increase the solubility of compound A in toluene is considered to be extremely difficult to operate, given the boiling point of hexane (68.7°C), as there is a risk of rapid vaporization of hexane. For this reason, it was considered that these conditions make it difficult to create a difference in solubility necessary for crystal precipitation. Even when hexane is added to the toluene crystallization solution at 70°C, the toluene solution of compound A is dilute, so it can be understood that the amount of compound A obtained per unit volume will be small. From these findings, it has become clear that the method for producing compound A described in Patent Document 1 is difficult or extremely inefficient in obtaining crystals, and is therefore unsuitable for industrial production.

[0029] <Example 1> In a four-necked flask equipped with a thermometer, stirrer, and condenser, 68.6 g of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene (compound A: Hazen unit color number (APHA) of a 10 wt% acetone solution is 190) was added to 99.0 g of acetone, and the flask was purged with nitrogen to dissolve the entire mixture. Then, 280.0 g of toluene was added and the mixture was heated to a maximum of 100°C to perform distillation to remove the acetone from the reaction vessel. A solid precipitate formed during the distillation of acetone. The weight of the recovered distillate was 102.2 g. After distillation, the solution in the reaction vessel was cooled from 100°C at a rate of 10°C / hour. The precipitated solid was filtered off by centrifugal filtration, washed with 35.2 g of toluene, and dried under reduced pressure at 80°C and 4.0 kPa for 5 hours to obtain 68.0 g of a pale yellow powder. The ratio of the weight of compound A in the obtained powder to the weight of compound A subjected to the crystallization process (yield of the crystallization process) was 91%. １ H-NMR and １３ The results of the 13C-NMR analysis are shown in Figures 1 and 2. HPLC analysis of the obtained powder revealed that it contained 98.8% (area percentage) of compound A and 0.5% (area percentage) of the monohydroxyethoxylated compound. The Hazen unit color number (APHA) of the solution hue of the obtained compound A powder in a 10 wt% acetone solution was 90. The Hazen unit color number (APHA) of the 10 wt% acetone solution of compound A subjected to the crystallization process was 190, indicating a significant improvement in hue due to the crystallization process. The sodium, potassium, and iron content of the obtained compound A powder was less than 0.1 ppm, and the copper content was 0.3 ppm. PXRD analysis revealed that the obtained powder was crystalline, as a diffraction pattern was observed. Table 1 shows the diffraction angle 2θ (°) of the observed diffraction peaks and the peaks with a relative intensity of 25 or higher relative to the peak with the highest intensity. The PXRD analysis chart is shown in Figure 3.

[0030]

[0031] The crystals obtained in Example 1 contained 7.4% by weight of toluene and 0.1% by weight of acetone. Based on data such as the solvent used for crystallization, NMR analysis, and weight loss from DTG analysis, the obtained crystals were presumed to be toluene inclusion complexes. The ratio of the weight of compound A in the obtained crystals to the weight of compound A subjected to the crystallization process was 91%. DSC analysis of the obtained crystals showed that the onset temperature of the endothermic peak was 200.1°C and the endothermic peak top temperature was 207.6°C. DSC data is shown in Figure 4. The results of TG / DTA analysis of the obtained crystals are shown in Figure 5. In TG / DTA analysis, almost no weight loss was observed even at temperatures exceeding the boiling point of toluene (110.6°C: 1 atm), and a steep weight loss was observed around 208°C (peak top temperature) where the endothermic peak appeared. The weight loss rate in the range of 200-220°C was 3.1%. Based on this weight loss behavior, it was inferred that the resulting compound A crystals contained toluene. The weight loss rate at 300°C was 6.03%.

[0032] <Evaluation of Solubility of Aliphatic Ketone Solvents> The solubility of aliphatic ketone solvents in dissolving compound A was evaluated using the crystals of compound A obtained in Example 1. For 0.5 g of compound A crystals, an aliphatic ketone solvent was added at room temperature (20°C), and the amount of solvent required for dissolution was measured to calculate the solute concentration of the aliphatic ketone solution. The dissolution of compound A crystals was confirmed visually. The aliphatic ketone solvents used to evaluate the solubility of compound A were acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone. The solute concentrations of each solvent are shown in Table 2.

[0033]

[0034] In Patent Document 1, the toluene solvent used to dissolve compound A had a solute concentration of 0.98% by weight at 70°C, as shown in Comparative Example 1, and a solute concentration of 2.96% by weight under heating reflux conditions at 130°C. In contrast, the aliphatic ketone solvent according to the present invention has the solubility shown in Table 2 at room temperature (20°C), indicating high solubility for dissolving compound A, and further increasing solubility for dissolving compound A at higher temperatures. Therefore, it has become clear that it is an organic solvent suitable for the industrial production of compound A by crystallization.

[0035] <Example 2> At room temperature, a solution was prepared by mixing 0.13 g of the compound A crystals obtained in Example 1 with 3.88 g of MEK in a screw-top bottle that could be sealed tightly. 21.50 g of toluene was added to this solution and mixed. The mixed solution was heated under reduced pressure to remove the solvent, resulting in the precipitation of powdered compound A. The precipitated powder was filtered by Kiriyama filtration, washed with toluene, and dried under reduced pressure at 70°C and 1.6 kPa for 5 hours to obtain 0.11 g of white powder. The yield of compound A powder obtained from these operations was 85%. The obtained powder was found to be crystalline, as a diffraction pattern was observed by PXRD analysis. Table 3 shows the diffraction angle 2θ (°) of the observed diffraction peaks and the peaks with a relative intensity of 10 or more relative to the peak with the highest intensity. The PXRD analysis chart is shown in Figure 6. The obtained crystals were found to be crystals with characteristic peaks common to the compound A crystals obtained in Example 1.

[0036]

[0037] The onset temperature of the endothermic peak in the differential scanning calorimetry (DSC) analysis of the obtained crystal was 199.5 °C, and the peak top temperature was 205.0 °C. The DSC analysis chart is shown in Fig. 7. In the DSC analysis of the obtained crystal, an endothermic peak was observed, which was considered to correspond to the melting of the crystal. The TG chart by TG-DTA analysis of the obtained crystal is shown in Fig. 8. Similar to the crystal obtained in Example 1, almost no weight loss was observed even at a temperature exceeding the boiling point of toluene (110.6 °C: 1 atm), and a sharp weight loss was observed around 205 °C (peak top temperature) where an endothermic peak appeared. The weight loss rate at 300 °C was 6.55%.

[0038] <Example 3>At room temperature, a solution was prepared by mixing 0.14 g of the crystal of Compound A obtained in Example 1 and 1.36 g of MIBK in a screw bottle with a sealable lid and dissolving them uniformly. 27.08 g of toluene was added to this solution and mixed. The sealed screw bottle containing the mixed solution was placed in a refrigerator (4 °C) and cooled. As a result, fine crystalline powder of Compound A was precipitated. Note that the fine crystalline state means a state where the shape can be visually recognized to some extent, such as needle-like or cube-like. Furthermore, the liquid was heated under reduced pressure to distill off the solvent, and after increasing the precipitated powder of Compound A, the precipitated powder was filtered off by Kiriyama filtration, washed with toluene, and dried under reduced pressure at 70 °C and 1.6 kPa for 5 hours to obtain 0.11 g of white powder. The yield of the powder of Compound A by these operations was 79%. Since a diffraction pattern was observed in the PXRD analysis for the obtained powder, it was revealed to be a crystal. Table 4 shows the diffraction angle 2θ (°) of the observed diffraction peaks and the peaks with a relative intensity of 15 or more based on the peak with the highest intensity. The PXRD analysis chart is shown in Fig. 9. It was revealed that the obtained crystal has characteristic peaks common to the crystal of Compound A obtained in Example 1.

[0039]

[0040] The onset temperature of the endothermic peak by differential scanning calorimetry (DSC) analysis of the obtained crystal was 204.5 °C, and the peak top temperature was 209.0 °C. The DSC analysis chart is shown in FIG. 10. In the DSC analysis of the obtained crystal, an endothermic peak was observed, which was considered to correspond to the melting of the crystal. The TG chart by TG-DTA analysis of the obtained crystal is shown in FIG. 11. Similar to the crystal obtained in Example 1, almost no weight loss was observed even at a temperature exceeding the boiling point of toluene (110.6 °C: 1 atm), and a sharp weight loss was observed around 209 °C (peak top temperature) where an endothermic peak appeared. The weight loss rate at 300 °C was 6.59%.

[0041] <Example 4>At room temperature, a solution was prepared by mixing 0.16 g of the crystal of Compound A obtained in Example 1 and 0.45 g of cyclohexanone in a screw bottle with a sealable lid and dissolving them uniformly. 31.01 g of toluene was added to this solution and mixed. The sealed screw bottle containing the mixed solution was placed in a refrigerator (4 °C) and cooled. As a result, fine crystalline powder of Compound A was precipitated. When the screw bottle was allowed to stand at room temperature, granular powder grown from the fine crystals was obtained. The precipitated powder was filtered off by Kiriyama filtration, washed with toluene, and dried under reduced pressure at 70 °C and 1.6 kPa for 5 hours to obtain 0.11 g of white powder. The yield of the powder of Compound A by these operations was 69%. Since a diffraction pattern was observed in the PXRD analysis for the obtained powder, it was revealed to be a crystal. Table 5 shows the diffraction angle 2θ (°) of the observed diffraction peaks and the peaks with a relative intensity of 10 or more based on the peak with the highest intensity. The PXRD analysis chart is shown in FIG. 12. It was revealed that the obtained crystal is a crystal having characteristic peaks common to the crystal of Compound A obtained in Example 1.

[0042]

[0043] Differential scanning calorimetry (DSC) analysis of the obtained crystals revealed an onset temperature of 204.1°C for the endothermic peak and a peak top temperature of 210.4°C. The DSC analysis chart is shown in Figure 13. The DSC analysis of the obtained crystals showed an endothermic peak, which was considered to correspond to the melting of the crystals. The TG chart obtained from TG-DTA analysis of the obtained crystals is shown in Figure 14. Similar to the crystals obtained in Example 1, almost no weight loss was observed even at temperatures exceeding the boiling point of toluene (110.6°C: 1 atm), and a steep weight loss was observed around 210°C (peak top temperature) where the endothermic peak appeared. The weight loss rate at 300°C was 6.58%.

[0044] The results from Examples 1 to 4 revealed that by isolating compound A in the crystalline form of the present invention, compound A can be isolated with high yield, and the resulting crystals also exhibit excellent hue. Furthermore, the crystal production method of the present invention is extremely useful because it allows for the isolation of compound A in crystalline form as an industrial production method, and the resulting compound A can be obtained as crystals with improved hue.

Claims

1. Crystals of 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene, having diffraction peaks at diffraction angles 2θ of 10.9±0.2°, 15.1±0.2°, and 19.7±0.2° in the powder X-ray diffraction peak pattern using Cu-Kα rays.

2. The crystal according to claim 1, wherein the peak top temperature of the endothermic peak determined by differential scanning calorimetry analysis is in the range of 203 to 213°C.

3. A method for producing crystals according to claim 1, comprising a crystallization step of precipitating the crystals from a crystallization solution containing 9,9-bis[9-(2-hydroxyethoxy)-3-phenanthryl]fluorene, an aliphatic ketone solvent having 3 to 6 carbon atoms, and toluene.

4. A method for producing crystals according to claim 3, comprising a crystallization step of precipitating crystals by evaporation crystallization, in which an aliphatic ketone solvent having 3 to 6 carbon atoms is evaporated from the crystallization solution.

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