KR102702691B1 - Crystals of 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl - Google Patents

Abstract

The present invention aims to provide a novel crystal of 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl, which is suitable as a resin raw material having excellent optical properties.
As a means for solving the above problem, the present invention has found that, by crystallization using a specific solvent, a crystal of 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl, represented by the chemical formula below, is obtained, which has an endothermic peak top temperature in a specific range as determined by differential scanning calorimetry, and also has a loose bulk density in a specific range.

Description

Crystals of 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl

The present invention relates to a novel crystal of a dicarboxylic acid compound and a method for producing the same. Specifically, it relates to a crystal of 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl, which has an endothermic peak top temperature within a specific range as determined by differential scanning calorimetry, and also has a loose bulk density within a specific range.

Recently, polyester resins and polyester carbonate resins that use a dicarboxylic acid component having a binaphthalene skeleton as a polymerization component have excellent optical properties such as high refractive index and low double refraction, and have high heat resistance, and are therefore expected to be used as raw materials for optical members such as optical disks, transparent conductive substrates, and optical filters. Among these, resins produced using 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl (hereinafter referred to as "compound A") having a chemical structure represented by the following chemical formula as a polymerization component are attracting attention in particular because of their excellent optical properties (e.g., Patent Documents 1 to 4, etc.).

As a method for producing compound A represented by the above formula, a method is known in which 1,1'-binaphthalene-2,2'-diol is reacted with a halogenated acetic acid ester such as ethyl chloroacetate, as shown in the reaction formula below, and the obtained diester is hydrolyzed (for example, Patent Document 5, etc.). However, since compound A obtained by the reaction is often used as a crude product without being purified and is converted into an acid chloride form using thionyl chloride, oxalyl chloride, etc., a purification method has not yet been examined or reported.

In addition, when the inventors of the present invention repeated the production of compound A, it was found that the dicarboxylic acid compound has crystals with different characteristics.

Japanese Patent Publication No. 2001-072872 Japanese Patent Publication No. 2018-002893 Japanese Patent Publication No. 2018-002894 Japanese Patent Publication No. 2018-002895 Japanese Patent Publication No. 2008-024650

The present invention has been made under the circumstances described above, and has as its object the provision of a new crystal of compound A suitable as a resin raw material having excellent optical properties.

The present inventors, as a result of careful examination to solve the aforementioned problem, discovered that by crystallization using a specific solvent, a crystal of compound A having an endothermic peak top temperature in a specific range as determined by differential scanning calorimetry and also having a loose bulk density in a specific range is obtained, thereby completing the present invention.

The present invention is as follows.

1. A crystal of 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl, characterized by an endothermic peak top temperature in the range of 215 to 220°C as determined by differential scanning calorimetry and a loose bulk density in the range of 0.3 to 0.6 g/cm3.

2. A crystal of 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl described in 1., wherein the Hazen colour number (APHA) of a 30 wt% solution obtained by dissolving the crystal in tetrahydrofuran is 100 or less.

3. A method for producing a crystal described in 1. or 2., characterized in that it is crystallized by any one of the solvents (1) to (5) below.

(1) At least one selected from chain ketone solvents having a total carbon number of 5 to 8;

(2) At least one selected from cyclic ketone solvents having a total carbon number in the range of 5 to 8.

(3) At least one selected from cyclic ether solvents having a total carbon number of 4 to 8.

(4) At least one selected from cyclic ester solvents having a total carbon number in the range of 4 to 8.

(5) A mixed solvent of water and at least one selected from chain ketone solvents having a total carbon number of 3 to 8.

4. A manufacturing method described in 3, characterized in that it is purified by any one of the solvents (1') to (5') below.

(1') Methyl isobutyl ketone or 2-octanone

(2') Cyclohexanone

(3') Tetrahydrofuran or 1,4-dioxane

(4') γ-butyrolactone or γ-valerolactone

(5') A mixed solvent of acetone and water or a mixed solvent of methyl ethyl ketone and water.

According to the present invention, it is possible to provide a crystal of compound A having an endothermic peak top temperature within a specific range as determined by differential scanning calorimetry and also having a loose bulk density within a specific range.

Since the crystal of the present invention has the characteristics of a high endothermic peak top temperature as determined by differential scanning calorimetry and a high loose bulk density, it is possible to efficiently manufacture, use, transport, etc. of the compound. In addition, when manufacturing an optical resin using the crystal of the compound as a raw material, not only can dust be suppressed from flying, so that adhesion or clogging of manufacturing equipment can be prevented, but also, when used as a reaction raw material, the capacity of the reaction vessel can be reduced, so that improved productivity can be expected. In addition, since it is also possible to reduce the capacity of the vessel during transport, it is possible to reduce transportation costs, and excellent effects in terms of operability can be exhibited.

In addition, since the crystal of the present invention is obtained by crystallization, it has the excellent characteristics of high purity and low discoloration.

That is, the provision of the crystal of the present invention and its manufacturing method is very useful for industrial use of resin raw materials, etc.

Figure 1 is a chart showing differential scanning calorimetry data of the crystals obtained in Example 1.
Figure 2 is a chart showing differential scanning calorimetry data of the crystals obtained in Example 2.
Figure 3 is a chart showing differential scanning calorimetry data of the crystals obtained in Example 3.
Figure 4 is a chart showing differential scanning calorimetry data of the solid obtained in Comparative Example 1.
Figure 5 is a chart showing differential scanning calorimetry data of the solid obtained in Comparative Example 2.

The present invention is described in detail below.

Compound A of the present invention is a compound represented by the chemical formula below.

＜About the synthesis method＞

There is no particular limitation on the method for synthesizing compound A of the present invention, but, for example, a production method may be exemplified, which comprises reacting a known 1,1'-binaphthalene-2,2'-diol with a halogenated acetic acid ester such as ethyl chloroacetate to obtain a diester, and then hydrolyzing the diester.

＜About the process of establishing a standard＞

The manufacturing method of the present invention is characterized in that it crystallizes using any one of the solvents (1) to (5) selected from (1) at least one solvent selected from chain ketone solvents having a total carbon number of 5 to 8, (2) at least one solvent selected from cyclic ketone solvents having a total carbon number of 5 to 8, (3) at least one solvent selected from cyclic ether solvents having a total carbon number of 4 to 8, (4) at least one solvent selected from cyclic ester solvents having a total carbon number of 4 to 8, or (5) at least one solvent selected from chain ketone solvents having a total carbon number of 3 to 8, and a mixed solvent of water.

Here, examples of the chain ketone solvent (1) having a total usable carbon number in the range of 5 to 8 include diethyl ketone, methyl isobutyl ketone, methyl amyl ketone, 2-octanone, etc., and among them, methyl isobutyl ketone, methyl amyl ketone, and 2-octanone, which have low solubility in water, are preferable. Examples of the cyclic ketone solvent (2) having a total usable carbon number in the range of 5 to 8 include cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, etc., and among them, cyclopentanone and cyclohexanone are preferable. Examples of the cyclic ether solvent (3) having a total usable carbon number in the range of 4 to 8 include oxetane, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, etc., and among them, tetrahydrofuran and 1,4-dioxane are preferable. Examples of the cyclic ester solvent (4) having a total usable carbon number in the range of 4 to 8 include γ-butyrolactone, γ-valerolactone, σ-valerolactone, and ε-caprolactone, and among them, γ-butyrolactone and γ-valerolactone are preferable. Examples of the chain ketone solvent (5) used as a mixed solvent with water include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl amyl ketone, and 2-octanone, and acetone and methyl ethyl ketone, which have high solubility in water, are preferable. There is no particular limitation as the usable water, and for example, tap water, distilled water, ion-exchanged water, natural water, etc. can be used appropriately.

Compound A used in the crystallization process of the present invention may include a crude crystal obtained by treating a reaction solution containing compound A, a crystal recrystallized from the crude crystal, a residue obtained by distilling off the solvent from a solution containing compound A, etc. It may also be amorphous. Compound A itself exists in two types of regular isomers, but a racemate is preferable as the compound A used in the crystallization process of the present invention, and the obtained crystal is also preferably a racemate.

In the case of using a chain ketone solvent (1) such as methyl isobutyl ketone or methyl amyl ketone that is not used as a mixed solvent with water, the amount of solvent for dissolving compound A is preferably 250 to 1,000 parts by weight, more preferably 300 to 800 parts by weight, and even more preferably 400 to 600 parts by weight, relative to 100 parts by weight of compound A contained in the crystals or solution used. When raising the temperature to dissolve the entire crystal, either normal pressure or pressurization may be used, and under pressure is preferable when the temperature is 450 parts by weight or less. The solution obtained by dissolving compound A in the ketone solvent may be cooled as it is and crystallized, but the crystals may be precipitated by distilling the ketone solvent from the solution while distilling it, or by cooling after distilling it. In the case of dissolving 500 parts by weight or more of chain ketone solvent relative to 100 parts by weight of compound A, it is preferable to distill the ketone solvent in order to improve the yield. Regarding the amount of the chain ketone solvent in the remainder after the solvent distillation, it is preferably adjusted to 150 to 450 parts by weight per 100 parts by weight of the crystals used, more preferably 200 to 400 parts by weight, and even more preferably 250 to 300 parts by weight. The temperature for precipitating the crystals is preferably 90 to 130°C, and even more preferably 95 to 105°C. The time required for solvent distillation is preferably 2 to 15 hours, more preferably 4 to 10 hours, and even more preferably 6 to 8 hours. In addition, it is also possible to obtain a ketone solution of compound A by adding the chain ketone solvent to an aqueous solution in which an alkali metal salt of compound A is dissolved, and then adding an acid. Thereafter, the aqueous layer is separated, and water is added to the obtained solvent layer, stirred, and a washing operation is performed to separate and remove the aqueous layer, and the same operation as above is performed to precipitate the crystals of compound A.

When using any one of a cyclic ketone solvent (2), a cyclic ether solvent (3), and a cyclic ester solvent (4), the amount of solvent for dissolving compound A is preferably 50 to 600 parts by weight, more preferably 50 to 400 parts by weight, and even more preferably 100 to 200 parts by weight, per 100 parts by weight of compound A contained in the crystal or solution used. When raising the temperature to dissolve the entire crystal, either normal pressure or pressurization may be used. Compound A may be dissolved in any one of a cyclic ketone solvent (2), a cyclic ether solvent (3), and a cyclic ester solvent (4), and the resulting solution may be cooled as is to crystallize, or the solvent may be distilled from the solution while distilling it, or may be cooled after being distilled to precipitate the crystal. The temperature for precipitating the crystal is preferably 90 to 110°C, and more preferably about 100°C, when a cyclic ketone solvent is used. When using a cyclic ether solvent, the temperature is preferably 55 to 75°C, more preferably 60 to 70°C. When using a cyclic ester solvent, the temperature is preferably 90 to 130°C, more preferably 115 to 125°C.

In the case of using a mixed solvent (5) of a chain ketone solvent and water, the concentration of the chain ketone solvent in the mixed solvent that dissolves compound A is preferably 95 to 65 wt%, more preferably 90 to 70 wt%, and even more preferably 85 to 75 wt%. In addition, the amount of the mixed solvent to be used is preferably 100 to 350 wt%, and more preferably 150 to 250 wt% relative to 100 wt% of compound A. When compound A is added to the mixed solvent (5) of the chain ketone solvent and water and the mixture is heated, a solution in which compound A is dissolved in the mixed solvent (5) of the chain ketone solvent and water is obtained. However, even if it is cooled as is, crystals may not precipitate due to the amount of solvent or water, or the yield may be low. Therefore, it is preferable to precipitate crystals by adding water to the solution obtained by dissolving compound A in a chain ketone solvent having a total carbon number in the range of 3 to 8, or to precipitate crystals by cooling after adding water. The weight ratio of the chain ketone solvent and water in the crystallization solution after the addition of water is preferably 150 to 400 parts by weight of water per 100 parts by weight of the chain ketone solvent, and more preferably 230 to 300 parts by weight. The crystal precipitation temperature when water is added to the mixed solvent is preferably 55 to 65°C, and more preferably around 60°C. The water addition time is preferably 1 to 5 hours, more preferably 1.5 to 2.5 hours, and even more preferably 2 hours.

In the crystallization operation using any one of the solvents (1) to (5) above, the cooling rate during crystallization and after crystal precipitation is preferably 5 to 15°C per hour, more preferably 7 to 12°C. In addition, when precipitating a crystal, it is not necessary to use a seed crystal, but it is preferable to use a seed crystal, and a crystal precipitated without a seed crystal can be used as the seed crystal. The final cooling temperature is preferably 20 to 60°C, more preferably 25 to 35°C. After cooling to the above temperature, the precipitated crystal is separated by a filtration operation.

＜About the drying process＞

By drying the crystals obtained by crystallization, the solvent used in crystallization can be removed. When drying the crystals obtained by crystallization, either normal pressure or reduced pressure can be used, but in the case of industrial use, it is more efficient to perform the drying under reduced pressure, and it is also preferable because the solvent used in crystallization can be removed. It can be performed preferably at 60 to 120°C under reduced pressure, more preferably at 70 to 110°C under reduced pressure.

＜Crystal of the present invention＞

The crystal of the present invention is characterized by having an endothermic peak top temperature in the range of 215 to 220°C as measured by differential scanning calorimetry, and a loose bulk density in the range of 0.3 to 0.6 g/cm3.

The loose bulk density of the present invention generally means a value measured by uniformly charging the measured granules into a container of a certain volume without creating a cavity or applying an external force such as vibration to the container, measuring the weight at that time, and dividing the weight by the container volume to obtain a value, and can be calculated from the measurement result by, for example, using a multi-functional powder property measuring instrument, a multitester (manufactured by Seishin Enterprise Co., Ltd.: MT-1001 type) or the like by a method described later. The loose bulk density of the crystal of the present invention is preferably a larger value within the range of 0.3 to 0.6 g/cm3. The lower limit in this numerical range is preferably 0.33 g/cm3 or more, and more preferably 0.4 g/cm3 or more. The upper limit in this numerical range is preferably a value closer to 0.6 g/cm3, and may be about 0.55 g/cm3 or less, or 0.5 g/cm3 or less.

The crystals shown in the comparative examples described below are crystals having endothermic peak top temperatures of 210°C, 214°C, and 215°C by differential scanning calorimetry, but since their loose bulk densities are 0.12 g/cm2 to 0.23 g/cm2, it can be confirmed that the crystals of the present invention have a great improvement in loose bulk density compared to the crystals of these comparative examples. That is, the crystals of the present invention not only can suppress dust or prevent adhesion or clogging of manufacturing equipment, but also exhibit excellent effects in terms of operability, such as reducing the capacity of the reaction vessel or transport vessel when used as a reaction raw material, thereby improving productivity and reducing transport costs.

The crystal of the present invention has an excellent characteristic called low coloring, and specifically, it is preferable that the Hazen color number (APHA) of a 30 wt% solution obtained by dissolving the crystal in tetrahydrofuran (purity 97% or higher) is 100 or less. Among these, it is more preferable that the Hazen color number (APHA) is 80 or less, further preferably 60 or less, and most preferably 30 or less. In order to obtain a low-colored crystal of the present invention, the above-described crystallizing step is preferably carried out in an inert gas atmosphere such as nitrogen, and the drying step is preferably carried out in an inert gas atmosphere such as nitrogen or under reduced pressure.

Example

Below, the present invention is specifically described by examples, but the present invention is not limited to these examples.

The analysis method is as follows.

＜Analysis method＞

1. Differential Scanning Calorimetry (DSC)

The crystals were precisely weighed in an aluminum pan and measured using a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation) under the following operating conditions, using aluminum oxide as a control.

(Operating conditions)

Heating rate: 10℃／min

Measurement temperature range: 30∼260℃

Measurement atmosphere: Open, nitrogen 50 mL/min

Sample amount: 3 mg ± 1 mg

2. Loose bulk density

Using a multi-functional powder property measuring instrument Multitester (manufactured by Seishin Enterprise Co., Ltd.: MT-1001 type), a crystal was gently placed through a sieve so as not to create an air gap in a measuring cell having a capacity of 20 cm3, and when the measuring cell was filled with the crystal, the weight a (g) of the crystal inside the cell was measured, and the loose bulk density was calculated from the following calculation formula.

[Calculation formula]

3. Powder X-ray diffraction (XRD)

0.1 g of the crystal was charged into the sample charging portion of a glass test plate, and measurement was performed using a powder X-ray diffraction device (SmartLab, manufactured by Rigaku Co., Ltd.) under the following conditions.

X-ray source: CuKα

Scan axis: 2θ／θ

Mode: Continuous

Measurement range: 2θ = 5°∼70°

Step: 0.01°

Speed measurement time: 2θ＝2°／min

IS: 1/2

　RS 　　　　　：20.00 ㎜

Output: 40 kV－30 mA

4. Color (APHA)

The decision was dissolved in tetrahydrofuran (manufactured by Fujifilm Wakushun Chemical Co., Ltd., purity 97% or higher) to obtain a 30 wt% solution, and after performing “standard calibration” of the measuring device below with tetrahydrofuran, the solution color of the 30 wt% solution was measured.

Measuring instrument: TZ 6000 manufactured by Nippon Denshoku Kogyo Co., Ltd.

＜Example 1＞

Crystals of 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl (compound A)

(the first one)

1,1'-binaphthalene-2,2'-diol (hereinafter referred to as "compound b") 52 g, N-methylpyrrolidone 156 g, potassium carbonate 58 g, and potassium iodide 5.2 g were placed in a four-necked flask, the temperature was raised to 70°C, and the mixture was stirred at the same temperature for 1 hour. While maintaining the temperature of the reaction solution at 65 to 70°C, 62 g of ethyl chloroacetate was added dropwise. After stirring for 4 hours, 156 g of water and 30 g of potassium hydroxide were added, and the mixture was stirred at 85 to 90°C for 13 hours. Next, 130 g of water and 156 g of methyl isobutyl ketone (hereinafter referred to as "MIBK") were added, and the mixture was stirred for 15 minutes while maintaining the temperature at 80 to 85°C, the aqueous layer was removed, and transferred to a separate four-necked reaction flask. To the aqueous layer, 416 g of MIBK and 416 g of water were added, and 100 g of concentrated hydrochloric acid was added dropwise while maintaining the temperature at 80 to 85°C, and the mixture was stirred at the same temperature for 30 minutes. Thereafter, the mixture was allowed to stand to remove the aqueous layer, water was added to the obtained oil layer, stirred, and then the mixture was allowed to stand to remove the aqueous layer. From the obtained oil layer, water and 252 g of MIBK were distilled off over 4 hours by atmospheric distillation under stirring. One hour after the start of distillation, crystals were precipitated without adding seed crystals. Thereafter, the mixture was cooled to 25°C at a cooling rate of 10°C per hour, the precipitated crystals were filtered off, and dried to obtain 60.7 g (yield: 82%) of powdered crystals of compound A.

The purity measured by high-performance liquid chromatography was 98.7%, the endothermic peak top temperature measured by differential scanning calorimetry was 217℃, the loose bulk density was 0.34 g/cm2, and the color (APHA) was 50.

A chart showing differential scanning calorimetry data is shown in Figure 1 (sample amount: 2.311 mg).

＜Example 2＞

Crystal of compound A (the second)

Compound b (1213 g), acetonitrile (3638 g), potassium carbonate (1346 g), and potassium iodide (121 g) were placed in a four-necked flask, heated to 70°C, and stirred at the same temperature for 1 hour. A mixed solution of 1460 g of ethyl chloroacetate and 13 g of N-methylpyrrolidone was prepared, and this mixed solution was added dropwise while maintaining the temperature of the reaction solution at 70 to 80°C. After stirring for 6 hours, 3032 g of water was added, the temperature was increased to 70°C, and the aqueous layer was removed. Next, 3392 g of a 35% potassium hydroxide aqueous solution was added dropwise while maintaining the reaction solution temperature at 70 to 80°C. After 2 hours, the reaction solution was gradually cooled, filtered at 25°C, and 2180 g of crystals of the potassium salt of compound A were obtained.

Subsequently, a crystallization process was performed under a nitrogen atmosphere. Of the obtained potassium salt crystals, 2051 g (solvent attachment: approximately 16 wt%) was used, and 3430 g of water and 9702 g of MIBK were placed in a four-necked flask and heated to 80°C to dissolve. 1207 g of concentrated hydrochloric acid was added dropwise while maintaining the temperature at 80 to 85°C, and the mixture was stirred at the same temperature for 30 minutes. Thereafter, the aqueous layer was removed, water was added, and washing was performed. Subsequently, water and 4713 g of MIBK were distilled off from the oil layer obtained at atmospheric pressure over 8 hours by distillation. After 2 hours from the start of distillation, 1 g of the crystals obtained in Example 1 were added as seed crystals to perform crystallization. The solution was cooled to 25°C at a cooling rate of 10°C per hour, filtered, and then dried under reduced pressure to obtain 1392 g (yield: 86.8%) of a crystal of compound A.

The purity measured by high-performance liquid chromatography was 99.9%, the endothermic peak top temperature by differential scanning calorimetry was 217℃, the loose bulk density was 0.45 g／cm3, and the color (APHA) was 30. In addition, the characteristic 2θ(deg) of XRD were 8.1, 9.2, 14.8, 16.2, 17.5, 18.2, 18.5, 22.7, 23.4, 24.4, 26.9, 27.5, 31.5, 36.3, and 39.2.

A chart showing differential scanning calorimetry data is shown in Figure 2 (sample amount: 2.952 mg).

＜Example 3＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 607 g of compound A and 1220 g of an 80% acetone aqueous solution were placed in a four-necked flask, heated to 50°C to dissolve. While maintaining the internal temperature at 55 to 60°C, 1100 g of water was added. Thereafter, 1 g of the crystals obtained in Example 1 were added as seed crystals, and while maintaining the temperature at 55 to 60°C, 1100 g of water was added over 2 hours to perform crystallization. The crystal solution was cooled to 25°C at a cooling rate of 10°C per hour, filtered, and then dried under reduced pressure to obtain 552 g (purification yield: 90.9%) of the crystals of the present invention.

The purity measured by high-performance liquid chromatography was 99.9%, the endothermic peak top temperature by differential scanning calorimetry was 218℃, the loose bulk density was 0.46 g／cm3, and the color (APHA) was 20. In addition, the characteristic 2θ(deg) of XRD were 8.1, 9.2, 14.8, 16.2, 18.5, 23.4, 24.4, 26.9, 27.5, 31.5, 36.3, and 39.2.

A chart showing differential scanning calorimetry data is shown in Figure 3 (sample amount: 1.988 mg).

＜Example 4＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 20 g of compound A and 120 g of 2-octanone were placed in a four-necked flask, heated to 145°C to dissolve, and then cooled at a cooling rate of 10°C per hour to confirm precipitation of crystals at 127°C. Thereafter, the crystal solution was cooled to 25°C, filtered, and then dried under reduced pressure to obtain 18.5 g (purification yield: 92.5%) of the crystal of the present invention.

The purity measured by high-performance liquid chromatography was 99.9%, the endothermic peak top temperature by differential scanning calorimetry was 215℃, the loose bulk density was 0.35 g／cm3, and the color (APHA) was 20. In addition, the characteristic 2θ(deg) of XRD were 8.1, 9.2, 14.8, 16.1, 18.2, 22.5, 23.4, 24.3, 26.8, and 36.3.

＜Example 5＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 20 g of compound A and 38.7 g of a 90% methyl ethyl ketone aqueous solution were placed in a four-necked flask, heated to 72°C to dissolve, and then cooled at a cooling rate of 10°C per hour to confirm precipitation of crystals at 55°C. Thereafter, the crystal solution was cooled to 25°C, filtered, and then dried under reduced pressure to obtain 6.5 g of the crystal of the present invention.

The purity measured by high-performance liquid chromatography was 99.9%, the endothermic peak top temperature by differential scanning calorimetry was 216℃, the loose bulk density was 0.32 g／cm3, and the color (APHA) was 10. In addition, the characteristic 2θ(deg) of XRD were 9.2, 14.6, 16.2, 18.2, 22.5, 23.3, 24.3, 26.8, and 36.3.

＜Example 6＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 20.1 g of compound A and 20.2 g of cyclohexanone were placed in a four-necked flask, heated to 146°C to dissolve, and then cooled at a cooling rate of 10°C per hour to confirm precipitation of crystals at 103°C. Thereafter, the crystal solution was cooled to 25°C, filtered, and then dried under reduced pressure to obtain 13.7 g of the crystal of the present invention.

The purity measured by high-performance liquid chromatography was 99.9%, the endothermic peak top temperature by differential scanning calorimetry was 215℃, the loose bulk density was 0.34 g／cm3, and the color (APHA) was 40. In addition, the characteristic 2θ(deg) of XRD were 9.2, 14.8, 16.2, 18.2, 23.4, 24.3, 26.8, and 36.3.

＜Example 7＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 15 g of compound A and 15.9 g of tetrahydrofuran were placed in a four-necked flask, heated to 65°C to dissolve, and then cooled at a cooling rate of 10°C per hour to confirm precipitation of crystals at 59°C. Thereafter, the crystal solution was cooled to 25°C, filtered, and then dried under reduced pressure to obtain 7.5 g of the crystal of the present invention.

The purity measured by high-performance liquid chromatography was 99.8%, the endothermic peak top temperature by differential scanning calorimetry was 215℃, the loose bulk density was 0.43 g／cm3, and the color (APHA) was 60. In addition, the characteristic 2θ(deg) of XRD were 9.2, 14.8, 16.2, 18.2, 18.4, 22.5, 23.4, 24.3, 26.8, and 36.3.

＜Example 8＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 15.1 g of compound A and 17.5 g of 1,4-dioxane were placed in a four-necked flask, heated to 101°C to dissolve, and then cooled at a cooling rate of 10°C per hour to confirm precipitation of crystals at 70°C. Thereafter, the crystal solution was cooled to 25°C, filtered, and then dried under reduced pressure to obtain 8.0 g of the crystal of the present invention.

The purity measured by high-performance liquid chromatography was 99.4%, the endothermic peak top temperature by differential scanning calorimetry was 215℃, the loose bulk density was 0.41 g／cm3, and the color (APHA) was 80. In addition, the characteristic 2θ(deg) of XRD were 8.1, 14.6, 16.1, 18.2, 22.5, 23.4, 24.4, 26.8, and 36.3.

＜Example 9＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 15 g of compound A and 10 g of γ-butyrolactone were placed in a four-necked flask, heated to 140°C to dissolve, and then cooled at a cooling rate of 10°C per hour to confirm precipitation of crystals at 103°C. Thereafter, the crystal solution was cooled to 25°C, filtered, and then dried under reduced pressure to obtain 13.1 g of the crystal of the present invention.

The purity measured by high-performance liquid chromatography was 99.8%, the endothermic peak top temperature by differential scanning calorimetry was 215℃, the loose bulk density was 0.33 g／cm3, and the color (APHA) was 130. In addition, the characteristic 2θ(deg) of XRD were 9.2, 14.7, 16.1, 18.2, 22.5, 23.3, 24.3, 26.8, and 36.3.

＜Example 10＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 20 g of compound A and 20 g of γ-valerolactone were placed in a four-necked flask, heated to 135°C to dissolve, and then cooled at a cooling rate of 10°C per hour to confirm precipitation of crystals at 123°C. Thereafter, the crystal solution was cooled to 25°C, filtered, and then dried under reduced pressure to obtain 16.7 g of the crystal of the present invention.

The purity measured by high-performance liquid chromatography was 99.7%, the endothermic peak top temperature by differential scanning calorimetry was 215℃, and the loose bulk density was 0.44 g／cm3. In addition, the characteristic 2θ(deg) of XRD were 8.0, 14.6, 16.1, 18.1, 23.3, 24.3, 26.9, and 36.2.

＜Comparative Example 1＞

A four-necked flask was charged with 4.0 g of compound b, 34.8 g of potassium carbonate, 20.1 g of bromoacetic acid, and 118 mL of methanol, and the mixture was heated to reflux for 6 hours. Methanol was removed from the reaction solution, water was added, and a 3N aqueous hydrochloric acid solution was added until the pH became 1. The reaction solution was transferred to a separatory funnel, and extracted five times with 30 mL of a 1:1 solution of benzene/diethyl ether. The extracted organic layers were collected, dehydrated with anhydrous sodium sulfate, and the solvent was distilled off using an evaporator to obtain a solid. By repeating the above reaction, the amount of solid required for analysis was obtained.

The purity measured by high-performance liquid chromatography was 96.0%, the endothermic peak top temperature measured by differential scanning calorimetry was 214℃, and the loose bulk density was 0.12 g/cm3.

A chart showing differential scanning calorimetry data is shown in Figure 4 (sample amount: 2.131 mg).

＜Comparative Example 2＞

Compound b (4.0 g), potassium carbonate (34.8 g), bromoacetic acid (20.1 g), and methanol (118 mL) were placed in a four-necked flask and reacted under reflux for 6 hours. Methanol was removed from the reaction solution, water was added, and a 3N hydrochloric acid aqueous solution was added until the pH became 1. 150 mL of a 1:1 solution of benzene/petroleum ether was added to the precipitated solid, but it did not dissolve, so filtration was performed as it was to obtain the solid. By repeating the above reaction, the amount of solid required for analysis was obtained.

The purity measured by high-performance liquid chromatography was 98.3%, the endothermic peak top temperature measured by differential scanning calorimetry was 210℃, and the loose bulk density was 0.14 g/cm3.

A chart showing differential scanning calorimetry data is shown in Figure 5 (sample amount: 2.536 mg).

＜Comparative Example 3＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 20 g of compound A and 158.3 g of methyl ethyl ketone were placed in a four-necked flask, heated to 79°C to dissolve, and then cooled at a cooling rate of 10°C per hour to confirm precipitation of crystals at 44°C. Thereafter, the crystal solution was cooled to 25°C, filtered, and then dried under reduced pressure to obtain 11.2 g of the crystal of the present invention.

The purity measured by high-performance liquid chromatography was 99.9%, the endothermic peak top temperature by differential scanning calorimetry was 215℃, the loose bulk density was 0.23 g／cm3, and the color (APHA) was 30. In addition, the characteristic 2θ(deg) of XRD were 9.2, 14.8, 16.3, 18.2, 22.5, 23.4, 24.4, 26.8, and 36.3.

＜Comparative Example 4＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 15 g of compound A and 237.1 g of butyl acetate were placed in a four-necked flask, heated to 125°C to dissolve, and then cooled at a cooling rate of 10°C per hour to confirm precipitation of crystals at 110°C. Thereafter, the crystal solution was cooled to 25°C, filtered, and then dried under reduced pressure to obtain 13.0 g of the crystal of the present invention.

The purity measured by high-performance liquid chromatography was 99.9%, the endothermic peak top temperature by differential scanning calorimetry was 215℃, the loose bulk density was 0.18 g／cm3, and the color (APHA) was 30. In addition, the characteristic 2θ(deg) of XRD were 9.2, 14.8, 16.1, 18.2, 22.5, 23.3, 24.3, 26.8, and 36.3.

＜Comparative Example 5＞

Using the compound A obtained in Example 2, a crystallization process was performed under a nitrogen atmosphere. 10 g of compound A and 210.1 g of cyclopentyl methyl ether were placed in a four-necked flask, heated to 103°C to dissolve, and then cooled at a cooling rate of 10°C per hour to confirm precipitation of crystals at 60°C. Thereafter, the crystal solution was cooled to 25°C, filtered, and then dried under reduced pressure to obtain 6.5 g of the crystal of the present invention.

The purity measured by high-performance liquid chromatography was 99.2%, the endothermic peak top temperature by differential scanning calorimetry was 215℃, the loose bulk density was 0.23 g／cm3, and the color (APHA) was 90. In addition, the characteristic 2θ(deg) of XRD were 9.2, 14.7, 16.2, 18.2, 22.5, 23.4, 24.3, 26.8, and 36.3.

Claims (4)

A crystal of 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl, characterized by an endothermic peak top temperature in the range of 215 to 220°C as determined by differential scanning calorimetry and a loose bulk density in the range of 0.3 to 0.6 g/cm3. In the first paragraph,
A crystal of 2,2'-bis(carboxymethoxy)-1,1'-binaphthyl having a Hazen color number (APHA) of 100 or less in a 30 wt% solution obtained by dissolving the crystal in tetrahydrofuran. A method for producing a crystal according to claim 1 or 2, characterized in that the crystal is crystallized by any one of the solvents (1') to (5') below.
(1') Methyl isobutyl ketone or 2-octanone
(2') Cyclohexanone
(3') Tetrahydrofuran or 1,4-dioxane
(4') γ-butyrolactone or γ-valerolactone
(5') A mixed solvent of acetone and water or a mixed solvent of methyl ethyl ketone and water. delete