Crystal of 2,2-bis(4-hydroxyphenyl)undecane and method for producing same

Abstract

The present invention addresses the problem of providing an isolate of 2,2-bis(4-hydroxyphenyl)undecane with a sufficiently high yield in a form suitable for industrial production. As a solution, provided is a crystal of 2,2-bis(4-hydroxyphenyl)undecane that exhibits an endothermic peak with a peak top temperature falling within the range of 92-107°C based on differential scanning calorimetric analysis.

Description

2,2-bis(4-hydroxyphenyl)undecane crystals and method for producing the same

[0001] The present invention relates to crystals of 2,2-bis(4-hydroxyphenyl)undecane and a method for producing the same.

[0002] Bisphenol compounds are useful compounds widely used as raw materials for polycarbonates and epoxy resins. They are also important compounds possessing properties such as high mechanical strength and impact resistance, excellent transparency, heat resistance and dimensional stability, and electrical insulation. These resins are highly anticipated because they can meet the high-performance requirements of automotive parts, electronic devices, building materials, medical devices, and the like. Meanwhile, Non-Patent Document 1 describes the synthesis and use of 2,2-bis(4-hydroxyphenyl)undecane (hereinafter sometimes referred to as "Compound A"), a type of bisphenol compound, as a raw material for epoxy resins, and describes its liquid nature. Patent Document 1 also describes an example of its use as a raw material for polymers. Furthermore, Patent Document 2 describes a method for producing a bisphenol compound having a long-chain alkyl moiety, in which Compound A is cited as an example of the bisphenol compound.

[0003] International Publication No. 2020 / 217699 Japanese Patent Application Laid-Open No. 2017-200913

[0004] Journal of Applied Polymer Science, 1960, Vol.3, p.296-301

[0005] Patent Document 1 describes an example of the production of a polymer using Compound A, but does not disclose the purity, form, or properties of Compound A, nor the production method by which it was obtained. However, since Non-Patent Document 1, a document prior to the publication of Patent Document 1, reveals that Compound A is liquid, it is highly likely that Patent Document 1 also treated Compound A as being in liquid form. Patent Document 2 describes a method for producing a bisphenol compound, for example, a production example of 1,1-bis(4-hydroxyphenyl)dodecane, but the yield is approximately 40%, which is not sufficiently high for industrial production. Furthermore, two types of solvents are used to precipitate the obtained bisphenol compound, making this a rather simple production method. The present invention was made against the background of the above-mentioned circumstances, and aims to obtain Compound A in a sufficiently high yield in a manner suitable for industrial production.

[0006] The present inventors have intensively investigated methods for isolating Compound A, and as a result have found that Compound A can be isolated as crystals in a sufficiently high yield in a manner suitable for industrial production, thereby completing the present invention.

[0007] The present invention is as follows: 1. A crystal of 2,2-bis(4-hydroxyphenyl)undecane, having an endothermic peak top temperature in the range of 92 to 107°C as determined by differential scanning calorimetry. 2. The crystal according to 1., having diffraction peaks at diffraction angles 2θ of 12.7±0.2°, 16.8±0.2°, and 21.0±0.2° in a powder X-ray diffraction peak pattern using Cu-Kα radiation. 3. The crystal according to 1. or 2., having a phenol content of 1.0% by weight or less. 4. The crystal according to 3., having an aliphatic saturated hydrocarbon solvent content of 5 to 10 carbon atoms of 1.0% by weight or less. 5. A method for producing the crystal according to 1., comprising a crystallization step of precipitating crystals of 2,2-bis(4-hydroxyphenyl)undecane from a crystallization solution containing 2,2-bis(4-hydroxyphenyl)undecane and an aliphatic saturated hydrocarbon solvent having 5 to 10 carbon atoms.

[0008] The crystals of Compound A of the present invention have easy-to-handle properties and are therefore suitable for industrial production, and can be efficiently obtained as highly pure Compound A. The method for producing crystals of Compound A of the present invention not only enables Compound A to be isolated as easily-handleable crystals, but also allows for an industrially feasible and efficient production process, enabling the production of highly pure Compound A.

[0009] 1 shows a differential scanning calorimetry (DSC) analysis chart of Crystal 2 of Compound A obtained in Example 1. FIG. 2 shows a powder X-ray diffraction (PXRD) analysis chart of Crystal 2 of Compound A obtained in Example 1.

[0010] The present invention will be described in detail below. 2,2-bis(4-hydroxyphenyl)undecane (compound A) according to the present invention is a compound having the following chemical structure:

[0011] <Reaction Step> There are no limitations on the method for producing Compound A according to the present invention, but it can be produced, for example, by a reaction step in which two equivalents of phenol and one equivalent of 2-undecanone are subjected to a dehydration condensation reaction. The amount of phenol used in the reaction step is preferably in the range of 2 to 10 moles, more preferably in the range of 2 to 6 moles, and particularly preferably in the range of 2 to 4 moles, per mole of 2-undecanone. The reaction temperature for producing Compound A depends on the boiling point of the reaction solvent used, and is preferably in the range of 10 to 80°C, more preferably in the range of 30 to 50°C, provided that it does not exceed that temperature. The reaction pressure for producing Compound A is usually carried out under atmospheric pressure; however, depending on the boiling point of the organic solvent used, the reaction may be carried out under increased or reduced pressure so that the reaction temperature falls within the above range. Furthermore, when hydrogen chloride gas is used as the acid catalyst, the reaction may be carried out under increased pressure. The method for mixing raw materials and the like in the reaction step is not particularly limited. For example, a mixing method in which the entire amount of raw materials and the like to be used is charged into a reaction vessel all at once, or a mixing method in which a mixed solution containing the remaining amount of 2-undecanone and phenol, and optionally a reaction solvent, is added to a solution containing a portion of the phenol to be used, an acid catalyst, and optionally a co-catalyst and reaction solvent, is preferably used. The latter mixing method is preferred from the viewpoints of reaction selectivity and the ability to adjust the reaction amount per hour. In this mixing method, it is preferable to carry out the reaction so that the mixing time is within a range of 0.5 to 5 hours and the amounts of raw materials used after mixing are as described above. The reaction time required to produce Compound A varies depending on the amount of catalyst and the reaction temperature, but is usually within a range of 1 to 48 hours, and it is preferable for the reaction to be completed within a range of 3 to 24 hours. The end point of the reaction to produce Compound A can be confirmed, for example, by liquid chromatography analysis or gas chromatography analysis. The end point of the reaction is preferably the time when unreacted 2-undecanone has disappeared or when no increase in the target compound A is observed.

[0012] (Acid Catalyst) An acid catalyst may be used in the reaction step, and either an inorganic acid or an organic acid can be used. Examples of inorganic acids include hydrogen chloride gas, hydrochloric acid, sulfuric acid, phosphoric acid, sulfuric anhydride, and the like. Examples of organic acids include aromatic sulfonic acids such as benzenesulfonic acid and p-toluenesulfonic acid, alkanesulfonic acids having 1 to 4 carbon atoms such as methanesulfonic acid and ethanesulfonic acid, trifluoromethanesulfonic acid, and trichloroacetic acid. Other examples of acid catalysts that can be used include metal halides such as aluminum chloride and iron chloride, and solid acids such as cation exchange resins. Among these, inorganic acids are preferred. Among inorganic acids, hydrogen chloride gas or hydrochloric acid is more preferred, and hydrogen chloride gas is particularly preferred. The amount of inorganic acid used is preferably 2.0 mol or less, more preferably 1.0 mol or less, per 1 mol of 2-undecanone.

[0013] (Reaction Solvent) In the reaction step, it is not necessary to use a reaction solvent if there are no problems with operability, but it may be used to improve operability during industrial production. The reaction solvent to be used is preferably selected appropriately depending on the ease of solubility of the raw materials used in the reaction step and the product Compound A. In addition, it is also preferable that the solvent does not distill out of the reaction vessel at the reaction temperature in the reaction to produce Compound A and is inert to the reaction. Examples of solvents that can be used include lower alcohols such as methanol, ethanol, and isopropanol, and water. These solvents are preferred, and water is particularly preferred. The amount of the solvent used is preferably in the range of 0.2 times by weight or less, more preferably 0.1 times by weight or less, relative to the amount of phenol used in the reaction.

[0014] (Co-catalyst) In the reaction step, a thiol compound may be used as a co-catalyst in combination with the acid catalyst, if necessary. The thiol compound is a compound having a mercapto group, and is not particularly limited as long as it does not adversely affect the reaction selectivity, etc. Examples of such compounds include carboxylic acids having a mercapto group, such as 3-mercaptopropionic acid and thioglycolic acid; alkyl mercaptans having 1 to 12 carbon atoms, such as methyl mercaptan, 1-octanethiol (octyl mercaptan), and 1-dodecanethiol (lauryl mercaptan); and mercaptoalcohols, such as mercaptoethanol and mercaptobutanol. Among these, alkyl mercaptans having 1 to 12 carbon atoms, such as 1-octanethiol, are preferred; methyl mercaptan, 1-octanethiol (octyl mercaptan), and 1-dodecanethiol (lauryl mercaptan) are more preferred; and methyl mercaptan is particularly preferred. These compounds may be used in the form of an aqueous solution of, for example, a sodium salt. The amount of the thiol compound used is preferably in the range of 0.01 to 0.50 mol, more preferably in the range of 0.01 to 0.10 mol, per 1 mol of 2-undecanone.

[0015] <Treatment after Completion of Reaction Step> It is preferable to carry out post-treatments such as mixing the reaction mixture after the reaction step with an alkaline aqueous solution such as an aqueous sodium hydroxide solution to neutralize the acid catalyst used in the reaction, or, if necessary, mixing with an organic solvent (e.g., an aliphatic hydrocarbon solvent having 5 to 10 carbon atoms) that dissolves Compound A and separates it from water, removing the separated aqueous layer, washing the oil layer from the solution with water, and removing by distillation the solvent used in the reaction step and the oil-water separation / washing operation, as well as the phenol used in excess in the reaction. Thereafter, in order to isolate Compound A, a crystallization operation to obtain crystals of Compound A of the present invention, as described below, or using the solution of excess phenol after completion of the reaction as a crystallization solution or a crystallization operation to obtain crystals by other methods, as well as a separation operation by column chromatography, can be carried out.

[0016] <Method for producing crystals of compound A of the present invention: Crystallization step> The method for producing crystals of compound A of the present invention is characterized by comprising a crystallization step of precipitating crystals of compound A from a crystallization solution containing compound A (2,2-bis(4-hydroxyphenyl)undecane) obtained by the method described above and an aliphatic saturated hydrocarbon solvent having 5 to 10 carbon atoms. Examples of the aliphatic saturated hydrocarbon solvent having 5 to 10 carbon atoms include chain aliphatic saturated hydrocarbon solvents having 5 to 10 carbon atoms such as pentane, hexane, heptane, octane, and isooctane, and cyclic aliphatic saturated hydrocarbon solvents having 5 to 10 carbon atoms such as cyclohexane. Among these, at least one solvent selected from pentane, hexane, heptane, octane, isooctane, and cyclohexane is preferred, and cyclohexane is particularly preferred. The amount of the aliphatic saturated hydrocarbon solvent having 5 to 10 carbon atoms used is in the range of 0.5 to 5.0 times by weight, more preferably 0.5 to 3.0 times by weight, even more preferably 0.5 to 2.0 times by weight, and particularly preferably 1.0 to 2.0 times by weight. The crystallization solution may contain water, which may be contained due to washing with water as described below, or other organic solvents (such as phenol used as a raw material, lower alcohols such as methanol and ethanol, and aromatic hydrocarbon solvents such as benzene, toluene, and xylene), as long as the effects of the present invention are not impaired. However, the total amount of Compound A and the aliphatic saturated hydrocarbon solvent having 5 to 10 carbon atoms in the crystallization solution is preferably 80% by weight or more, more preferably 90% by weight or more, and even more preferably 95% by weight or more, based on the weight of the entire crystallization solution. It is particularly preferred to use the aliphatic saturated hydrocarbon solvent having 5 to 10 carbon atoms alone to prepare a crystallization solution with Compound A. Before precipitating crystals of Compound A in the crystallization step, the crystallization solution may be mixed with water and the separated aqueous layer removed or the oil layer washed with water, as necessary, to remove impurities such as water-soluble metals, salts, and organic substances, and treatments such as reduced pressure distillation and steam distillation may also be performed to remove the solvent and phenol used in the reaction, and such treatments are preferred.When precipitating crystals, seed crystals may not be used, but their use is preferred. There are no limitations on the crystals used as seed crystals; however, crystals of the present invention initially obtained without seed crystals may be used as seed crystals. The amount of seed crystals used is preferably in the range of 0.1 to 1.0 wt % relative to the compound A to be precipitated. The temperature at which crystals are precipitated from the prepared solution described above depends on the boiling point of the crystallization solvent used, but is preferably in the range of 5 to 60°C, provided that it does not exceed this boiling point. The crystal precipitation temperature is more preferably in the range of 5 to 40°C, even more preferably in the range of 10 to 40°C, and particularly preferably in the range of 15 to 40°C. After crystal precipitation begins, it is preferable to maintain the same temperature to increase the amount of crystal precipitation. The holding time is not particularly limited, but is usually in the range of 1 to 48 hours, preferably in the range of 3 to 24 hours. After the amount of crystal precipitation has increased, the liquid containing the crystals can be cooled, with the final cooling temperature being preferably 10 to 30°C. The cooling rate during cooling is preferably in the range of 3 to 20°C / hour, more preferably in the range of 5 to 15°C / hour. The precipitated crystals may be reheated to a temperature at which the crystals dissolve and recooled in order to dissolve fine crystals and improve the slurry properties and particle size distribution, or they can be isolated by filtration. The filtered crystals are preferably washed with water or an organic solvent. The organic solvent used is preferably the aliphatic saturated hydrocarbon solvent having 5 to 10 carbon atoms used in the crystallization step. The amount of the organic solvent used is preferably in the range of 0.5 to 10.0 times by weight, more preferably 0.5 to 5.0 times by weight, even more preferably 1.0 to 5.0 times by weight, and particularly preferably 1.0 to 3.0 times by weight, relative to the amount of the crystals of Compound A.

[0017] (Treatment after crystal isolation) The filtered crystals are subjected to a drying step in which they are dried under predetermined conditions, thereby removing the solvent adhering to the crystals. The drying temperature is in the range of 10 to 70°C, preferably in the range of 10 to 50°C, more preferably in the range of 20 to 45°C, and particularly preferably in the range of 30 to 45°C. Drying may be carried out under normal pressure or reduced pressure, but when carried out industrially, a reduced pressure of about 20 kPa is preferred, a reduced pressure of about 10 kPa is more preferred, a reduced pressure of about 5 kPa is even more preferred, and a reduced pressure of about 2 kPa is particularly preferred, since this allows the solvent used to be removed.

[0018] <Crystals of Compound A of the Present Invention> The crystals of Compound A (2,2-bis(4-hydroxyphenyl)undecane) of the present invention have an endothermic peak top temperature in the range of 92 to 107°C in differential scanning calorimetry. The peak top temperature is more preferably in the range of 95 to 105°C, even more preferably in the range of 95 to 104°C, and particularly preferably in the range of 101 to 104°C. The crystals of Compound A of the present invention further preferably have diffraction peaks at diffraction angles 2θ of 12.7±0.2°, 16.8±0.2°, and 21.0±0.2° in a powder X-ray diffraction peak pattern using Cu-Kα radiation. In the powder X-ray diffraction peak pattern using Cu-Kα radiation, in addition to the above peaks, it is more preferable that the diffraction angle 2θ further includes diffraction peaks at 19.1±0.2° and 19.4±0.2°, and in addition to these peaks, it is even more preferable that the diffraction angle 2θ further includes diffraction peaks at 9.5±0.2° and 18.5±0.2°. Note that the peaks in the powder X-ray diffraction using Cu-Kα radiation preferably have a relative intensity of 10 or more, more preferably 25 or more, with the most intense peak as the reference (relative intensity of 100); however, the relative intensity may vary depending on the measurement device and conditions, or in the case of a mixture with other crystals, and therefore the crystalline phase can be identified based on an analysis method of ordinary powder X-ray diffraction analysis. The purity of the crystal of compound A of the present invention is preferably 95.0% or more, more preferably 97.0% or more, even more preferably 98.0% or more, particularly preferably 99.0% or more, as 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.The method for HPLC analysis of the purity of the crystal of the present invention is a method according to the HPLC analysis in the analytical method of the Examples described below.The crystal of compound A of the present invention may contain the phenol used as raw material, and the content of this phenol is preferably 1.0 wt% (10,000 ppm) or less, more preferably 0.5 wt% (5,000 ppm) or less, more preferably 0.1 wt% (1,000 ppm) or less, even more preferably 0.05 wt% (500 ppm) or less.The phenol content in the crystals of the present invention can be analyzed by a method conforming to the HPLC analysis (quantitative) in the analytical methods of the Examples described later. The crystals of Compound A of the present invention may contain the aliphatic saturated hydrocarbon solvent having 5 to 10 carbon atoms used as the crystallization solvent, and the content thereof is preferably 1.0 wt% (10,000 ppm) or less, more preferably 0.5 wt% (5,000 ppm) or less, even more preferably 0.1 wt% (1,000 ppm) or less, and particularly preferably 0.05 wt% (500 ppm) or less. The phenol content in the crystals of the present invention can be analyzed by a method conforming to the HPLC analysis (quantitative) in the analytical methods of the Examples described later.

[0019] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. <Analysis method> 1. High-performance liquid chromatography (HPLC) analysis device and conditions (1) Device and conditions High-performance liquid chromatography analysis device Prominence UFLC (Shimadzu Corporation) Column oven: CTO-20A Detector: SPD-20A Column: HALO C18 column 3.0 x 75 mm Oven temperature: 50°C Flow rate: 0.7 mL / min. Mobile phase: (A) 0.2% by volume aqueous acetic acid, (B) methanol Gradient conditions: (B) vol% (time from start of analysis) 50% (0 min) → 100% (12 min) → 100% (3 min) Sample injection volume: 5 μL Detection wavelength: 280 nm (2) Measurement of selectivity of Compound A in the reaction solution 100-200 mg of the reaction solution was placed in a 50 mL volumetric flask and dissolved by adding methanol up to the marked line on the volumetric flask. The obtained sample solution was analyzed using the apparatus and conditions described in (1) above, and the composition was calculated based on the detected peak area. (3) Measurement of purity and phenol content of Compound A crystals 20-40 mg of the crystals were placed in a 50 mL volumetric flask and dissolved by adding methanol up to the marked line on the volumetric flask. The obtained sample solution was analyzed using the apparatus and conditions described in (1) above. The area percentage of Compound A in the HPLC analysis was taken as the purity of Compound A. The amount of phenol contained was measured by the absolute calibration curve method.

[0020] 2. Headspace gas chromatography (HS-GC) (1) HS-GC analytical equipment and conditions Gas chromatography Equipment: GC-2010 Plus / Shimadzu Corporation Column: InertCap-1 60 m × 0.25 mm Φ / GL Sciences Inc. Film thickness: 0.25 μm Detector: FID Vaporization chamber temperature: 300 ° C. Detector temperature: 310 ° C. Column temperature: 40 ° C. Column heating conditions (retention time): 40 ° C. (10 min) → 20 ° C. / min → 300 ° C. (5 min) Make-up 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: TurboMatrix HS40 / PerkinElmer Co., Ltd. HS carrier gas pressure: 154.0 kPa Oven temperature: 100°C Needle temperature: 105°C Transfer temperature: 105°C Incubation time: 20 minutes Pressurization time: 3 minutes Withdrawal time: 0.5 minutes Injection time: 0.05 minutes (2) Measurement of solvent content in crystals of Compound A (cyclohexane) For the component to be quantified (cyclohexane), multiple NMP solution samples with different concentrations were prepared 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. 0.15 g of the crystals was dissolved in 9.85 g of N-methylpyrrolidone, and 2.90 g of the resulting sample solution was analyzed using the apparatus and conditions described in (1) above. The amount of solvent contained in the crystals was calculated using the calibration curve.

[0021] 3. Differential Scanning Calorimetry (DSC) (Analysis Method) 2-5 mg of crystals were placed in an aluminum sample container, and the container was pressed with a lid attached to create a sample. The resulting sample was analyzed using the following equipment and conditions. (Equipment and Conditions) Equipment: DSC7020 / Hitachi High-Tech Science Corporation Heating rate: 10°C / min. Measurement temperature range: 30-300°C. Measurement atmosphere: Nitrogen 50 mL / min.

[0022] 4. Powder X-ray diffraction (PXRD) analysis The crystals were thoroughly ground in a mortar and filled into a measurement cell. The obtained sample was analyzed using the following equipment and conditions. (Measurement conditions) Equipment: MiniFlex 600-C / Rigaku Corporation X-ray source: CuKα Scan axis: 2θ / θ Mode: Continuous Measurement range: 2θ = 5° to 90° Step: 0.02° Speed ​​measurement time: 10° / min. Entrance slit: 0.25° Receiving slit: 13.00 mm Tube voltage: 40 kV Tube current: 15 mA

[0023] Example 1 Phenol (657.2 g) and water (32.9 g) were charged into a 5 L four-neck flask equipped with a thermometer, a stirrer, and a condenser, and the atmosphere inside the flask was replaced with nitrogen. Next, hydrogen chloride gas was blown into the flask over one hour at a liquid temperature of 15 to 30°C, and 15% aqueous methyl mercaptan solution (25.7 g) was added at 35 to 40°C. A mixed solution of 2-undecanone (473.5 g) and phenol (261.6 g) was prepared, and the prepared mixed solution was added over two hours while maintaining the liquid temperature in the flask at 35 to 40°C. The mixture was then stirred at the same temperature for three hours. The selectivity of Compound A in the reaction solution at the end of stirring was 95%. 75% phosphoric acid (44.7 g) and 16% aqueous sodium hydroxide solution (601.0 g) were added to the reaction solution to neutralize it, and water (238.5 g) was then added. The mixture was heated to a liquid temperature of 60 to 65°C, and the aqueous layer (194.3 g) was removed from the liquid that separated into two layers. Thereafter, the oil layer was washed twice with water (238 g) at a liquid temperature of 66 to 73°C. The liquid was then cooled to a temperature of 15°C, and stirred overnight to precipitate crystals. The precipitated crystals were separated by centrifugation and washed with cyclohexane (955.3 g). The obtained crystals of Compound A (referred to as "Crystal 1") had a purity of 99.5% by the above-mentioned HPLC analysis. The obtained Crystal 1 and cyclohexane (1368.7 g) were mixed, and the liquid temperature was heated to 72°C to dissolve the crystals. Thereafter, water (250.1 g) was mixed, and the liquid temperature was heated to 60 to 65°C. The aqueous layer (240.2 g) was removed from the liquid that separated into two layers. The resulting oil layer was heated to an internal pressure of 0.7 kPa and a liquid temperature of 117°C and distilled to obtain 1,441.3 g of a liquid containing cyclohexane and water. Furthermore, water (150.0 g) was added and distilled at an internal pressure of 1.0 kPa and a liquid temperature of 117°C to obtain 130.5 g of a liquid containing cyclohexane and water. This process was repeated twice. After distillation, cyclohexane (1,815.1 g) and water (250.3 g) were added to the oil, and the mixture was heated to a liquid temperature of 60-65°C. The liquid separated into two layers, and the aqueous layer (205.5 g) was removed. The solution from which the aqueous layer was removed was cooled to 31°C and then further cooled to 25°C. The temperature was then raised again to 35°C, cooled to 25°C, and stirred overnight.The precipitated crystals were filtered by centrifugal filtration and washed with cyclohexane (1,195.9 g). The solvent-containing crystals (980.9 g) obtained by filtration were dried at 40°C for 4 hours using an evaporator under a reduced pressure of 1 kPa or less. Through the above operations, 786.0 g (82% yield) of crystals (referred to as "crystals 2") were obtained. The purity of the obtained crystals 2 of Compound A was 99.6% by the above HPLC analysis. The obtained crystals 2 contained cyclohexane (18 ppm or less) and phenol (35 ppm). The DSC analysis chart of the obtained crystals 2 is shown in Figure 1, and the PXRD analysis chart is shown in Figure 2. The obtained crystals 2 showed an endothermic peak at 102°C (peak top temperature) in the DSC analysis. This is believed to correspond to the melting of the crystals. The obtained crystals 2 were also confirmed to be crystals by PXRD analysis, as a diffraction pattern was also observed. Table 1 shows the diffraction angles 2θ (°) of the diffraction peaks that appeared and the peaks with a relative intensity of 25 or more based on the peak with the greatest intensity.

[0024]

[0025] Compound A has conventionally been in liquid form, but the present invention, which is in crystalline and powder form, is very useful for industrial production. Furthermore, since the crystals of the present invention obtained in the examples have a low solvent content, it is possible to reduce the amount of solvent exposure during storage and transportation of Compound A and during the production of resins and derivatives using the same, thereby contributing to the health of workers handling the compound A and the preservation of the environment. The production method for obtaining the crystals of the present invention is very useful because it allows Compound A to be obtained in a crystalline form containing a small amount of organic solvent with high purity and improved yield.

Claims

1. Crystals of 2,2-bis(4-hydroxyphenyl)undecane, the peak top temperature of which is in the range of 92 to 107°C when measured by differential scanning calorimetry.

2. The crystal according to claim 1, which has diffraction peaks at diffraction angles 2θ of 12.7±0.2°, 16.8±0.2°, and 21.0±0.2° in a powder X-ray diffraction peak pattern using Cu-Kα radiation.

3. The crystals described in claim 1 or 2, wherein the phenol content is 1.0% by weight or less.

4. The crystal according to claim 3, wherein the content of the aliphatic saturated hydrocarbon solvent having 5 to 10 carbon atoms is 1.0% by weight or less.

5. A method for producing the crystals according to claim 1, comprising a crystallization step of precipitating crystals of 2,2-bis(4-hydroxyphenyl)undecane from a crystallization solution containing 2,2-bis(4-hydroxyphenyl)undecane and an aliphatic saturated hydrocarbon solvent having 5 to 10 carbon atoms.

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