Crystals of diester compounds with binaphthyl skeletons

Abstract

The present invention provides crystals of a novel diester compound having a binaphthyl skeleton, which can be obtained more easily by crystallization than 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl. [Solution] As a result of extensive research, we have found that a novel diester compound having a binaphthyl skeleton represented by the following formula (1) can be more easily crystallized than 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl. JPEG0007740862000015.jpg35113

Description

[Technical Field]

[0001] The present invention relates to a crystal of a novel diester compound having a binaphthyl skeleton. [Background technology]

[0002] In recent years, polyester resins and polyester carbonate resins, which contain a dicarboxylic acid component having a binaphthyl skeleton as a polymerization component, have been expected to be used as raw materials for optical components such as optical disks, transparent conductive substrates, and optical filters because of their excellent optical properties such as high refractive index and low birefringence, and high heat resistance.

[0003] [ka] Resins having a structural unit represented by the formula (I) have attracted attention as resins with excellent optical properties, and such resins are produced, for example, using 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl as a polymerization component (see, for example, Patent Documents 1 to 3). 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl is also produced, for example, by reacting 1,1'-binaphthalene-2,2'-diol with a halogenated acetic acid ester such as ethyl chloroacetate (see, for example, Patent Documents 4 and 5). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-002893 [Patent Document 2] Japanese Patent Application Publication No. 2018-002894 [Patent Document 3] Japanese Patent Application Publication No. 2018-002895 [Patent Document 4] Patent Publication No. 2021-017406 [Patent Document 5] Japanese Patent Application Laid-Open No. 2008-024650 Summary of the Invention [Problem to be solved by the invention]

[0005] Because raw material monomers for optical resins may adversely affect the optical properties of the resins, they are required to be highly pure. Therefore, when raw material monomers with high boiling points are produced on an industrial scale, purification by crystallization is the norm.

[0006] However, the above-mentioned 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl remains in a liquid state even after purification using silica gel column chromatography (Patent Document 5), and even if crystals are obtained by crystallization, a method that is difficult to implement on an industrial scale (specifically, a method in which 1,1'-binaphthalene-2,2'-diol and ethyl chloroacetate are reacted in an acetonitrile solvent, the resulting reaction mixture is washed with water, the acetonitrile is removed, a portion of the resulting residue is added to a 75% aqueous acetone solution, and the mixture is left in a freezer overnight) is used to obtain seed crystals, and crude crystals can only be isolated from the reaction mixture using the seed crystals (Patent Document 4). As such, 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl has extremely poor crystallinity or is too soluble in solvents, making it difficult to highly purify the compound on an industrial scale, and therefore it cannot be said to be preferable as a raw material monomer for optical resins.

[0007] An object of the present invention is to provide crystals of a novel diester compound having a binaphthyl skeleton that can be more easily obtained by crystallization. [Means for solving the problem]

[0008] As a result of extensive research aimed at solving the above problems, the present inventors have found that the above problems can be solved by using a compound represented by the following formula (1), and have thus completed the present invention. Specifically, the present invention includes the following inventions.

[0009] [1] The maximum melting endothermic temperature measured by differential scanning calorimetry is 173.0°C to 176.9°C, and the maximum melting endothermic temperature measured by differential scanning calorimetry is the following formula (1):

[0010] [ka] A crystal of the compound represented by the formula:

[0011] [2] In a powder X-ray diffraction pattern using Cu-Kα radiation, the compound has peaks at diffraction angles 2θ=7.1±0.2°, 7.5±0.2°, 14.1±0.2°, 18.8±0.2°, 19.5±0.2°, and 21.2±0.2° of the following formula (1):

[0012] [ka] A crystal of the compound represented by the formula:

[0013] [3] In a powder X-ray diffraction pattern using Cu-Kα radiation, the compound has peaks at diffraction angles 2θ=7.4±0.2°, 18.7±0.2°, 19.4±0.2°, and 21.1±0.2° of the following formula (1):

[0014] [ka] A crystal of the compound represented by the formula:

[0015] [4] The maximum melting endothermic temperature measured by differential scanning calorimetry is 173.0°C to 176.9°C, and the powder X-ray diffraction pattern measured by Cu-Kα radiation has peaks at diffraction angles 2θ=7.1±0.2°, 7.5±0.2°, 14.1±0.2°, 18.8±0.2°, 19.5±0.2°, and 21.2±0.2°, represented by the following formula (1):

[0016] [ka] A crystal of the compound represented by the formula:

[0017] [5] The maximum melting endothermic temperature measured by differential scanning calorimetry is 173.0°C to 176.9°C, and the powder X-ray diffraction pattern measured by Cu-Kα radiation has peaks at diffraction angles 2θ=7.4±0.2°, 18.7±0.2°, 19.4±0.2°, and 21.1±0.2°, which are represented by the following formula (1):

[0018] [ka] A crystal of the compound represented by the formula: [Effects of the Invention]

[0019] According to the present invention, it is possible to provide crystals of a novel diester compound having a binaphthyl skeleton (i.e., crystals of the compound represented by formula (1) of the present invention having the characteristics described below) that can be obtained by crystallization more easily than 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl. Furthermore, since crystals of the compound represented by formula (1) of the present invention can be crystallized more easily than 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl, they can be recovered with higher yield and purity. Furthermore, crystals of the compound represented by formula (1) of the present invention can be further purified by recrystallization. Therefore, crystals of the compound represented by formula (1) of the present invention are more suitable than 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl as a raw material monomer for a resin having a structural unit represented by formula (A), for example.

[0020] In addition, as will be shown in the Examples section below, the crystals of the compound of the present invention represented by the above formula (1) have a higher melting point (maximum temperature of melting endotherm determined by differential scanning calorimetry) than 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl, and are therefore expected to have better blocking resistance. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a 1H-NMR chart of the compound represented by the above formula (1). [Figure 2] 1 is a 13C-NMR chart of the compound represented by the above formula (1). [Figure 3] FIG. 1 is a diagram showing a differential scanning calorimetry (DSC) curve of the crystal of the compound represented by the above formula (1) obtained in Example 1 (the crystal of the present invention). [Figure 4] FIG. 1 is a diagram showing a powder X-ray diffraction pattern of the crystal of the compound represented by formula (1) obtained in Example 1 (crystal of the present invention). [Figure 5] FIG. 2 is a diagram showing a differential scanning calorimetry (DSC) curve of the crystal of the compound represented by the above formula (1) obtained in Example 2 (the crystal of the present invention). [Figure 6] FIG. 2 is a diagram showing the powder X-ray diffraction pattern of the crystal of the compound represented by formula (1) obtained in Example 2 (the crystal of the present invention). DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will be described in detail below. In this specification, when a numerical range is expressed as "A to B", it means A or more and B or less.

[0023] The crystals of the compound of the present invention represented by the above formula (1) can be produced by the production method described below, and have a melting point (maximum temperature of melting endotherm measured by differential scanning calorimetry) of 173.0°C to 176.9°C.

[0024] Furthermore, the crystal of the compound of the present invention represented by the above formula (1) has typical peaks at diffraction angles 2θ=7.1±0.2°, 7.5±0.2°, 14.1±0.2°, 18.8±0.2°, 19.5±0.2°, 21.2±0.2°, 26.0±0.2°, and 27.1±0.2° in a powder X-ray diffraction pattern using Cu-Kα radiation, due to differences in the production method described below, and in particular, at diffraction angles 2θ=7.1±0.2°, 7.5±0.2°, 14.1±0.2°, 18.8±0.2°, 19.5±0.2°, 21.2±0.2°, 26.0±0.2°, and 27.1±0.2°. 2θ=7.1±0.2°, 7.5±0.2°, 14.1±0.2°, 18.8±0.2°, 19.5±0.2°, and 21.2±0.2° (hereinafter, this may be referred to as Pattern A), or it has characteristic peaks at diffraction angles 2θ=7.4±0.2°, 18.7±0.2°, 19.4±0.2°, and 21.1±0.2° (hereinafter, this may be referred to as Pattern B).

[0025] The crystal of the compound of the present invention represented by the above formula (1) has a maximum melting endothermic temperature of 173.0°C to 176.9°C in differential scanning calorimetry and / or exhibits the above pattern A in the powder X-ray diffraction pattern using Cu-Kα radiation.

[0026] Furthermore, the crystal of the compound of the present invention represented by the above formula (1) has a maximum melting endothermic temperature of 173.0°C to 176.9°C in differential scanning calorimetry and / or exhibits the above pattern B in the powder X-ray diffraction pattern using Cu-Kα radiation.

[0027] Crystals of the compound of the present invention represented by the formula (1) can be produced, for example, by a production method including a step of crystallizing using a mixture of an alkyl phenyl ether having 7 to 10 carbon atoms and methanol as a crystallization solvent (hereinafter, this step may be referred to as the crystallization step). Alternatively, for example, crystals of the compound of the present invention represented by the formula (1) produced by the above production method can be used as seed crystals, and crystallization can be carried out using aromatic hydrocarbons as a crystallization solvent. The "crystallization step" will be described in detail below.

[0028] In the mixture of alkyl phenyl ether having 7 to 10 carbon atoms and methanol, examples of the alkyl phenyl ether having 7 to 10 carbon atoms include methoxybenzene (anisole), ethoxybenzene (phenetole), propoxybenzene, isopropoxybenzene, butoxybenzene, 1-methylpropoxybenzene, 2-methylpropoxybenzene, and tert-butoxybenzene, and preferred are methoxybenzene (anisole) and ethoxybenzene (phenetole). These alkyl phenyl ethers having 7 to 10 carbon atoms may be used alone or in combination of two or more. In the mixture of alkyl phenyl ether having 7 to 10 carbon atoms and methanol, the weight ratio of alkyl phenyl ether having 7 to 10 carbon atoms to methanol is, for example, 1:1 to 20:1, and preferably 5:1 to 15:1.

[0029] The amount of the crystallization solvent used is, for example, 1 to 15 parts by weight per part by weight of the compound represented by the above formula (1). When the reaction mixture obtained in the reaction step described below is used as is in the crystallization step, the amount of the compound represented by the above formula (1) contained in the reaction mixture can be measured, for example, by an absolute calibration curve method or an internal standard method using liquid chromatography.

[0030] Examples of methods for crystallizing the compound represented by formula (1) include dissolving the compound represented by formula (1) in a crystallization solvent, cooling the resulting solution to precipitate crystals, and filtering off the precipitated crystals. The temperature at which the compound represented by formula (1) is dissolved in the crystallization solvent may be, for example, 10°C or more higher than the temperature at which the crystals are precipitated, which will be described later. The temperature at which the resulting solution is cooled to precipitate crystals is, for example, 20°C to 60°C. Note that seed crystals may be used when precipitating the crystals.

[0031] Thereafter, further cooling may be carried out as necessary. The cooling rate is, for example, 0.1°C / min to 20°C / min, and the cooling end temperature is, for example, 0°C to 25°C. Then, the crystals can be isolated by a conventional method such as filtration or centrifugation. The isolated crystals usually contain a solvent, but the solvent can be removed by drying. Drying can be carried out, for example, by heating under normal pressure or reduced pressure. The heating temperature is, for example, 70°C to 90°C.

[0032] The thus obtained crystals of the compound represented by the above formula (1) can be further purified by recrystallization, distillation, adsorption, column chromatography, or the like.

[0033] In the production method of the present invention, which comprises a step of crystallizing the crystals of the compound represented by the above formula (1) as seed crystals using aromatic hydrocarbons as crystallization solvents, examples of aromatic hydrocarbons used include toluene, xylene, o-xylene, m-xylene, p-xylene, ethylbenzene, etc. Although the solution may contain solvents other than aromatic hydrocarbons, it is preferable that no other solvents are contained. The amount of solvent used, crystallization conditions, etc., in this method can be carried out in the same manner as in the above-mentioned crystallization method, except that the addition of seed crystals is essential. Note that if seed crystals are not added, the crystals of the present invention cannot be obtained.

[0034] The compound represented by the above formula (1) used in the present invention can be prepared, for example, by reacting a compound represented by the following general formula (2):

[0035] [ka] (In the formula, R 1a , R 1b each independently represents an alkyl group having 1 to 6 carbon atoms, which may be branched.) The compound represented by formula (1) can be produced by reacting a compound represented by formula (1) with diphenyl carbonate or phenyl acetate (hereinafter referred to as the reaction step). For example, when a general method for producing 2,2'-bis(alkoxycarbonylmethoxy)-1,1'-binaphthyl, such as the method for producing 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl described in Patent Documents 4 and 5, in which a halogenated alkyl acetate is reacted with 1,1'-bi-2-naphthol in the presence of a base, is applied to produce the compound represented by formula (1), the reaction mixture after the reaction contains a large amount of by-products, as described in Reference Example 1 below, making it difficult to isolate the compound represented by formula (1) of the present invention. The reaction step is described in detail below. The reaction step is described in detail below.

[0036] R in the above general formula (2) 1a , R 1b The alkyl group having 1 to 6 carbon atoms in the formula (I) may be linear or branched, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group.

[0037] The compound represented by the general formula (2) may be purified by a conventional method (for example, the crystals described in Patent Document 4), or may be unpurified (for example, the compound represented by the general formula (2) contained in the reaction mixture obtained by reacting 1,1'-bi-2-naphthol with a halogenated acetate). In particular, since the crystals of the compound represented by formula (1) of the present invention have low solubility in commonly used organic solvents such as aromatic hydrocarbons, even if the unpurified compound represented by the general formula (2) is used as a raw material, impurities contained in the previous step can be easily removed by crystallization after the reaction.

[0038] Examples of organic titanium compounds include alkoxy titanium catalysts. Examples of alkoxy titanium catalysts include tetramethyl ester, tetra-n-propyl ester, tetraisopropyl ester, tetra-n-butyl ester, tetraisobutyl ester, tetra-tert-butyl ester, tetra-2-ethylhexyl ester, tetraoctyl ester, tetraphenyl ester, tetrabenzyl ester, and tetratolyl ester of titanic acid. These organic titanium compounds may be used alone or in combination of two or more.

[0039] The amount of the organic titanium compound used is, for example, 0.025 to 0.10 moles per mole of the compound represented by the general formula (2) above.

[0040] The amount of diphenyl carbonate or phenyl acetate used is, for example, 4 to 25 moles per mole of the compound represented by the above general formula (2).

[0041] The reaction of the compound represented by the general formula (2) with diphenyl carbonate or phenyl acetate may be carried out using diphenyl carbonate or phenyl acetate as a solvent, or may be carried out in the presence of an organic solvent other than diphenyl carbonate or phenyl acetate. Examples of the organic solvent include aromatic hydrocarbons. Examples of the aromatic hydrocarbon include toluene, xylene, and mesitylene. When using an organic solvent, the amount used is, for example, 0.05 to 5.0 parts by weight per part by weight of the compound represented by the general formula (2). These organic solvents may be used alone or in combination of two or more.

[0042] The reaction of the compound represented by the general formula (2) with diphenyl carbonate or phenyl acetate can be carried out, for example, at 130°C to 170°C. If necessary, the reaction may be carried out under normal pressure or reduced pressure while removing by-products. When the reaction is carried out under reduced pressure, the internal pressure is, for example, 0.67 kPa to 6.7 kPa.

[0043] After the reaction step is carried out, the resulting reaction mixture may be used in the crystallization step as is, or may be used in the crystallization step after, if necessary, post-treatments such as neutralization and washing with water, concentration, etc. Alternatively, the compound represented by formula (1) may be isolated from the resulting reaction mixture by crystallization, column chromatography, etc., and used in the crystallization step. Alternatively, the isolated compound represented by formula (1) may be purified by recrystallization, distillation, adsorption, column chromatography, etc., if necessary, before being used in the crystallization step. [Example]

[0044] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Various measurements and tests in the examples were carried out by the methods described below. Furthermore, the "purity" described in the examples is an area percentage value measured by HPLC under the following conditions.

[0045] [1] HPLC measurement Equipment: Shimadzu LC-2030 Column: XBridge Phenyl (3.5 μm, 4.6 mm diameter x 150 mm) Column temperature: 40℃ Detection wavelength: UV 254nm Mobile phase: Solution A = ultrapure water containing 0.1% formic acid, Solution B = acetonitrile containing 0.1% formic acid (The concentration of Solution B was varied as shown below during analysis.) B liquid concentration: 40% (5min hold) → 30min → 70% (10min hold) → 5min → 100% (10min) ·Mobile phase flow rate: 1.0ml / min Sample injection volume: 5 μL

[0046] [2] NMR measurement 1 H-NMR and 13 C-NMR was recorded on a JEOL-ESC400 spectrometer using tetramethylsilane as an internal standard and deuterated chloroform (CDCl3) as the solvent.

[0047] [3] LC-MS measurement Equipment: Waters Xevo G2 Q-Tof Column: L-Column2 ODS (2 μm, 2.1 mm diameter x 100 mm) Column temperature: 40℃ Detection wavelength: UV 200-500nm Mobile phase: Solution A = 10 mM ammonium acetate in methanol, Solution B = methanol (The concentration of Solution B was varied as shown below for analysis.) B liquid concentration: 60% (1min hold) → 7min → 90% (2min hold) ·Mobile phase flow rate: 0.35ml / min Detection method: Q-Tof Ionization method: ESI(+) method Ion Source: Voltage (+) 2.0kV, Temperature 120℃ Sampling Cone: Voltage 10V, Gas flow 50L / h Desolvation Gas: Temperature 400℃, Gas flow 1000L / h

[0048] [4] Differential scanning calorimetry (DSC) Five mg of crystals of the compound represented by formula (1) above were precisely weighed into an aluminum pan and measured using a differential scanning calorimeter (SII NanoTechnology Inc.: DSC7020) under the following operating conditions using aluminum oxide as a control. (Operating conditions) Heating rate: 10℃ / min Measurement range: 30-300℃, Atmosphere: Open, nitrogen 40ml / min.

[0049] [5] Powder X-ray diffraction 150 mg of crystals of the compound represented by the formula (1) were filled into the sample filling section of a glass test plate, and measured using a powder X-ray diffractometer (Spectris: X'PertPRO) under the following conditions. X-ray source: CuKα, Output: 1.8kW (45kV-40mA), Measurement range: 2θ=5°~70° Scan speed: 2θ = 2° / min, Slit: DS=1°, Mask=15mm, RS=variable (0.1mm~).

[0050] <Production Example 1> Production example of the compound represented by the above formula (1) (hereinafter, sometimes referred to as "compound of formula (1)") A glass reactor equipped with a stirrer, heater / cooler, and thermometer was charged with 50 g (0.18 mol) of 1,1'-bi-2-naphthol, 150 g of acetonitrile, 55.5 g (0.40 mol) of potassium carbonate, and 5 g of potassium iodide. The internal temperature was raised to 80°C and stirred at that temperature for 1 hour. Next, 59.9 g (0.49 mol) of ethyl chloroacetate was added dropwise while maintaining the temperature of the reaction solution at 70 to 80°C. After stirring at the same temperature for 24 hours, 125 g of ion-exchanged water was added dropwise to the reaction solution to dissolve the inorganic salts, and the aqueous layer was separated. The resulting organic layer was then concentrated to remove water and a portion of the acetonitrile. Then, 150 g of toluene was added, and the organic layer was washed with water. Thereafter, the obtained organic layer was concentrated to distill off water and a part of the toluene, thereby obtaining 111.4 g of a toluene solution of 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl (containing 25.1% by weight of toluene). 187 g (0.87 mol) of diphenyl carbonate was added to the toluene solution at 25 ° C., and the internal temperature was raised to 80 ° C. to dissolve the diphenyl carbonate. Next, 1.3 g (0.0046 mol) of tetraisopropyl orthotitanate was added, and the internal pressure was reduced to 1.3 kPa. The internal temperature was then raised to 150 ° C., and the reaction was carried out for 8 hours while distilling off toluene and by-products at the same temperature. After that, crystals precipitated when the internal temperature was cooled to 100 ° C., so 150 g of toluene was added, and the internal temperature was raised to 110 ° C. to re-dissolve the precipitated crystals. Next, the internal temperature was cooled to 85 ° C., and crystals were precipitated without adding seed crystals. After that, the internal temperature was cooled to 5 ° C. at a cooling rate of 10 ° C. / hour. Subsequently, the crystals precipitated at the same temperature were filtered off, and the obtained crystals were dried under reduced pressure at 1.3 kPa for 11 hours while being heated in a water bath at 90°C, thereby obtaining 73.2 g of the compound represented by the above formula (1) as crystals.

[0051] Furthermore, the obtained compound represented by the above formula (1) was subjected to NMR measurement and LC-MS measurement according to the above measurement methods. 1 H-NMR, 13 The C-NMR and LC-MS spectral values ​​are shown below. 1 H-NMR, 13 The C-NMR measurement chart is shown below.

[0052] [ 1 H-NMR (CDCl3)] δ(ppm)=4.78(4H, s), 6.92(4H, d), 7.17-7.22(6H, m), 7.29-7.34(6H, m), 7.44(2H, d), 7.88(2H, d), 7.99(2H, d).

[0053] [ 13 C-NMR (CDCl3)] δ(ppm)=67.08, 115.44, 120.46, 121.23, 124.30, 125.66, 126.01, 126.68, 127.96, 129.39, 129.85, 129.93, 133.99, 150.06, 153.57, 167.84.

[0054] [LC-MS] Mass spectrometry value ([M+NH4] + ):572.20650 (The calculated molecular weight (ESI+; [C 36 H 26 O6 + NH4] + ):572.20676).

[0055] Example 1 A glass reactor equipped with a stirrer, heater / cooler, and thermometer was charged with 10.0 g of the crystals of the compound of formula (1) obtained as in Production Example 1, 45.5 g of anisole, and 4.5 g of methanol (anisole:methanol=10:1), and the internal temperature was raised to 70°C to dissolve the compound of formula (1). The mixture was then cooled to an internal temperature of 0°C at a cooling rate of 12°C per hour and maintained at that temperature for 3 hours. During cooling, precipitation of crystals was confirmed at an internal temperature of 52°C. The precipitated crystals were filtered and then dried under reduced pressure to obtain 4.8 g of crystals of the compound of formula (1). The DSC chart of the obtained crystals of the compound of formula (1) is shown in Figure 3, and the X-ray diffraction pattern is shown in Figure 4. The main X-ray diffraction peaks (those with a relative intensity of more than 5%) obtained by powder X-ray diffraction are shown in Table 1. The maximum melting endothermic temperature of the obtained crystals of the compound of formula (1) was 176.9°C as measured by DSC.

[0056] [Table 1]

[0057] <Example 2> A glass reactor equipped with a stirrer, heater / cooler, and thermometer was charged with 10.0 g of the crystals of the compound of formula (1) obtained as in Preparation Example 1 and 55.0 g of toluene. The internal temperature was raised to 110 °C to dissolve the compound of formula (1), and then the internal temperature was cooled to 90 °C. Subsequently, 0.03 g of the crystals of the present invention obtained in Example 1 was added as seed crystals and the mixture was maintained at the same temperature for 1 hour, confirming the precipitation of crystals. The mixture was further cooled to 0 °C at a cooling rate of 10 °C per hour and maintained at the same temperature for 3 hours. The precipitated crystals were then filtered and dried under reduced pressure to obtain 8.6 g of crystals of the compound of formula (1). The DSC chart of the resulting crystals of the compound of formula (1) is shown in Figure 5, and the X-ray diffraction pattern is shown in Figure 6. The main X-ray diffraction peaks (those with a relative intensity greater than 5%) obtained by powder X-ray diffraction are shown in Table 2. The maximum melting endothermic temperature of the obtained crystals of the compound of formula (1) was 176.8°C as measured by DSC.

[0058] [Table 2]

[0059] <Comparative Example 1> Crude crystals of 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl were produced in the same manner as described in <Synthesis Example> of Patent Document 4. Using the obtained crude crystals, crystals of 2,2'-bis(ethoxycarbonylmethoxy)-1,1'-binaphthyl were obtained in the same manner as described in <Example 1> of Patent Document 4. The maximum melting endothermic temperature of the obtained crystals measured by DSC was 110.5°C.

[0060] <Reference example 1> A glass reactor equipped with a stirrer, heater / cooler, and thermometer was charged with 0.5 g (0.0018 mol) of 1,1'-bi-2-naphthol, 1.5 g of 4-methyltetrahydropyran, 1.0 g (0.0072 mol) of potassium carbonate, and 0.05 g of potassium iodide. The mixture was heated to 120°C and stirred at the same temperature for 1 hour. Next, 0.94 g (0.0044 mol) of phenyl bromoacetate was added dropwise while maintaining the temperature of the reaction mixture at 100-120°C. After stirring for 1 hour, the reaction mixture was analyzed by HPLC. It was found to be a complex mixture containing a large amount of by-products, and the compound represented by formula (1) could not be isolated.

Claims

1. The maximum melting endothermic temperature measured by differential scanning calorimetry is 173.0°C to 176.9°C, and the maximum melting endothermic temperature measured by differential scanning calorimetry is 173.0°C to 176.9°C. 【Chemical 1】 A crystal of the compound represented by the formula:

2. In a powder X-ray diffraction pattern using Cu-Kα radiation, the compound represented by the following formula (1) has peaks at diffraction angles 2θ=7.1±0.2°, 7.5±0.2°, 14.1±0.2°, 18.8±0.2°, 19.5±0.2°, and 21.2±0.2°: 【Chemistry 2】 A crystal of the compound represented by the formula:

3. In a powder X-ray diffraction pattern using Cu-Kα radiation, the compound represented by the following formula (1) has peaks at diffraction angles 2θ=7.4±0.2°, 18.7±0.2°, 19.4±0.2°, and 21.1±0.2°: 【Chemistry 3】 A crystal of the compound represented by the formula:

4. The compound represented by the following formula (1): has a melting endothermic maximum temperature of 173.0°C to 176.9°C as determined by differential scanning calorimetry, and has peaks at diffraction angles 2θ=7.1±0.2°, 7.5±0.2°, 14.1±0.2°, 18.8±0.2°, 19.5±0.2°, and 21.2±0.2° in a powder X-ray diffraction pattern using Cu-Kα radiation: 【Chemistry 4】 A crystal of the compound represented by the formula:

5. The compound represented by the following formula (1): has a melting endothermic maximum temperature of 173.0°C to 176.9°C as determined by differential scanning calorimetry, and has peaks at diffraction angles 2θ=7.4±0.2°, 18.7±0.2°, 19.4±0.2°, and 21.1±0.2° in a powder X-ray diffraction pattern using Cu-Kα radiation: 【Chemistry 5】 A crystal of the compound represented by the formula:

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