Crystals of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane and method for producing the same

Abstract

The present invention provides crystalline 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane with good handling properties and a method for producing the same. [Solution] Provides a crystalline form of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane whose maximum endothermic temperature determined by differential scanning calorimetry is in the range of 195 to 225°C.

Description

Technical Field

[0001] The present invention relates to crystals of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane and a method for producing the same.

Background Art

[0002] Although 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane is known to be usable as a raw material monomer for polyphenylene ether and epoxy resin (for example, Patent Document 1), details of the physical properties of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane are not known at all.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 2 described a method for producing 4,4’,4”-ethylidene tris-2-methylphenol, and a mixed solvent of an aromatic hydrocarbon solvent and an aliphatic ketone solvent was used in the crystallization operation. However, these crystallization solvents are not suitable for industrial production due to problems such as low recycling efficiency and high production costs, which was a major issue in industrial production. Furthermore, Patent Document 3, mentioned above, describes a method for producing tris(4-hydroxyphenyl) compounds, stating that a trisphenol reaction mixture can be mixed with a non-solvent for trisphenol to precipitate trisphenol from the reaction solution. As a specific example, the document describes that, among the tris(4-hydroxyphenyl) compounds, the presence or absence of precipitation was confirmed using various solvents for 1,1,1-tris(4-hydroxyphenyl)ethane, and that methylene chloride and 1,2-dichloroethane were the most preferred. The inventors have shown that even when the method described above is applied to 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane, which is a compound according to the present invention, it is not possible to obtain crystals as shown in the comparative example described later.

[0005] The present invention was made against the background described above, and aims to provide a crystalline form of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane with good handling properties and a method for producing the same. [Means for solving the problem]

[0006] As a result of diligent research to solve the above-mentioned problems, the inventors discovered that 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane can be crystallized in a single solvent, and thus completed the present invention.

[0007] The present invention is as follows: 1. A crystalline form of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane with a maximum endothermic temperature in the range of 195-225°C, as determined by differential scanning calorimetry. 2. Loose bulk density is 0.25~0.6 g / cm³ 3 The crystals described in 1. are within the range of 1. 3. The crystalline material according to 1. or 2., wherein the powder X-ray diffraction peak pattern using Cu-Kα rays has diffraction peaks at diffraction angles 2θ of 11.0±0.2°, 12.9±0.2°, 16.1±0.2°, 17.5±0.2°, and 22.2±0.2°. A method for producing a crystal according to any one of items 1 to 3, characterized by cooling a solution containing 100 parts by weight of 4,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane and 250 to 1500 parts by weight of an aromatic hydrocarbon solvent to precipitate crystals. [Effects of the Invention]

[0008] This invention is the first to reveal the previously unknown physical properties of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane as a crystalline material, and because this crystalline material has excellent handling properties, it is extremely useful. In particular, since the crystalline material of the present invention can be obtained by crystallization using a single solvent, it is possible to significantly reduce raw material costs in industrial production, making it extremely useful. [Brief explanation of the drawing]

[0009] [Figure 1] This graph shows the differential scanning calorimetry (DSC) data of the crystal obtained in Example 1. [Figure 2] This graph shows the differential scanning calorimetry (DSC) data of the crystal obtained in Example 2. [Figure 3] This chart shows the powder X-ray diffraction data obtained using Cu-Kα rays for the crystal obtained in Example 2. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below. The 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane in this invention is a compound having the following chemical structure. [ka]

[0011] <Synthesis method> 1,1,1-Tris(4-hydroxy-3,5-dimethylphenyl)ethane can be obtained by a conventionally known production method. Specifically, as shown in the following reaction formula, it can be obtained by a condensation reaction of 4-hydroxy-3,5-dimethylacetophenone and 2,6-dimethylphenol. [Chemical formula]

[0012] As the amount of 2,6-dimethylphenol used with respect to 4-hydroxy-3,5-dimethylacetophenone in the above reaction, 2 to 50 moles, more preferably 3 to 30 moles, and still more preferably 4 to 20 moles of 2,6-dimethylphenol are preferably used per 1 mole of 4-hydroxy-3,5-dimethylacetophenone. The reaction temperature is preferably 20 to 70°C, more preferably 30 to 60°C. Also, the reaction is usually carried out under normal pressure, but depending on the boiling point of the solvent used, it may be carried out under pressure or reduced pressure so that the reaction temperature is within the above range. In the above reaction, it is preferable to use an acidic catalyst such as an inorganic acid, an organic acid, a metal halide, or a solid acid such as a cation exchange resin as a catalyst. Specifically, for example, hydrogen chloride gas, hydrochloric acid, sulfuric acid, phosphoric acid, sulfuric anhydride, p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, trichloroacetic acid, aluminum chloride, iron chloride, etc. can be mentioned. When using hydrogen chloride gas, it is preferable to introduce dry hydrogen chloride gas into a solution or slurry liquid composed of 2,6-dimethylphenol and a solvent and / or a promoter to make it saturated, and then sequentially add 4-hydroxy-3,5-dimethylacetophenone to carry out the reaction. As the amount of this acidic catalyst used, a range of 0.1 to 20.0 moles, more preferably a range of 0.5 to 10.0 moles, is preferable per 1 mole of 4-hydroxy-3,5-dimethylacetophenone. Furthermore, in the above reaction, a co-catalyst may be used in combination with the acidic catalyst. Specifically, examples include thiols such as methyl mercaptan, ethyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, mercaptoacetic acid, and β-mercaptopropionic acid. The amount of this co-catalyst used is preferably 2 to 30 mol%, and more preferably 4 to 20 mol%, relative to 4-hydroxy-3,5-dimethylacetophenone.

[0013] The above reaction is usually carried out in the presence of a solvent. The solvent is not particularly limited as long as it does not inhibit the reaction, but examples include lower (C1-C4) aliphatic alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; aromatic hydrocarbons such as toluene and xylene; ethers such as tetrahydrofuran and dioxolane; saturated aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; and water. These solvents can be used alone or in combination. Furthermore, the amount of solvent used is not particularly limited as long as it does not hinder the reaction, but it is usually used in the range of 1 to 100 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of 2,6-dimethylphenol. While the method of adding raw materials during the reaction is not particularly limited, a preferred method from the viewpoint of reaction selectivity is to mix a mixture of the remaining 2,6-dimethylphenol and 4-hydroxy-3,5-dimethylacetophenone with a solution containing a portion of 2,6-dimethylphenol, an acidic catalyst, and, if necessary, a co-catalyst. In the case of mixing, the mixing time should be within the range of 0.5 to 5 hours. The reaction should be carried out so that the resulting solution matches the amount of raw materials used as described above. The above reaction involves the dehydration condensation of 4-hydroxy-3,5-dimethylacetophenone and 2,6-dimethylphenol, which produces water. Carrying the reaction under dehydration conditions, which remove water from the reaction system such as the reaction product water and catalyst-containing water, is preferable because it allows the reaction to proceed faster, suppresses the formation of by-products, and allows for obtaining the target product in higher yields compared to when dehydration is not performed. Dehydration methods are not particularly limited, but examples include dehydration by adding a dehydrating agent, dehydration by reduced pressure, and dehydration by azeotrope with a solvent at atmospheric pressure or reduced pressure.

[0014] <Post-processing> The endpoint of the reaction can be confirmed by liquid chromatography or gas chromatography analysis. It is preferable to define the endpoint of the reaction as the point at which unreacted 4-hydroxy-3,5-dimethylacetophenone disappears or when the increase in the target product, 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane, ceases. To obtain the target product from the reaction-completed mixture, known methods can be used as appropriate. For example, an alkaline aqueous solution containing an alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, or potassium carbonate is added to the reaction-completed mixture to roughly neutralize it. Then, an acid such as phosphoric acid or hydrochloric acid is added to neutralize it to a pH of 4-8. After neutralization, the aqueous layer containing the neutralized salt is separated and removed. After separating the aqueous layer, the oil layer is washed by adding water and repeating the operations of stirring, standing, and separating and removing the aqueous layer multiple times. After thorough washing, it is preferable to distill the water-washed oil layer to remove the solvent and 2,6-dimethylphenol.

[0015] <Method for manufacturing crystals> The crystalline material in this invention can be obtained by dissolving 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane in an aromatic hydrocarbon solvent, and then cooling the solution to crystallize it, i.e., precipitate crystals. Specific examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, and mesitylene, among which toluene, xylene, or mesitylene are preferred, toluene or xylene are more preferred, and toluene is particularly preferred. The amount of aromatic hydrocarbon solvent used is preferably in the range of 250 to 1500 parts by weight, more preferably in the range of 300 to 1000 parts by weight, even more preferably in the range of 300 to 800 parts by weight, and particularly preferably in the range of 300 to 600 parts by weight, per 100 parts by weight of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane. It is preferable to use 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane that has undergone the "post-treatment" step described above for crystallization, and the content of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane in the crude product obtained in this way is preferably 60% by weight or more, more preferably 70% by weight or more, even more preferably 75% by weight or more, and particularly preferably 80% by weight or more. The crude product of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane used for crystallization may contain 2,6-dimethylphenol used as a raw material. The amount of 2,6-dimethylphenol is preferably small, but is in the range of 0 to 40% by weight, preferably in the range of 0 to 35% by weight, more preferably in the range of 0 to 30% by weight, and particularly preferably in the range of 0 to 20% by weight. The sum of the content of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane, 2,6-dimethylphenol, and other components in such crude products is 100% by weight. The crystallization conditions are as follows: the crystal precipitation temperature is preferably in the range of 30 to 120°C; the cooling rate is preferably 1 to 10°C per hour, preferably 3 to 7°C per hour; and the holding time at the same temperature after crystal precipitation is preferably 30 minutes to 1 hour. The precipitated crystals can be obtained by filtering them from the crystallization solvent using methods such as suction filtration or centrifugal filtration. The temperature for this process is preferably 10 to 30°C, and more preferably 20 to 25°C. Furthermore, when drying the crystals obtained by filtration, it is preferable to do so under reduced pressure, with a temperature of 50 to 190°C being preferred, and more preferably 60 to 170°C.

[0016] <Crystal of the present invention> The crystal of the present invention has an endothermic maximum temperature in the range of 195 to 225°C, determined by differential scanning calorimetry. Preferably, the endothermic maximum temperature is in the range of 200 to 220°C, more preferably in the range of 202 to 218°C, even more preferably in the range of 205 to 216°C, and particularly preferably in the range of 207 to 214°C. Furthermore, the crystalline material of the present invention has a loose bulk density of 0.25 to 0.6 g / cm³. 3 It is preferable that the density falls within this range. The lower limit of this loose bulk density is 0.30 g / cm³. 3 It is preferable that this is the case. Furthermore, the upper limit of the loose bulk density is 0.50 g / cm³. 3 Preferably, it is 0.40 g / cm³. 3 It is more preferable that it be 0.35 g / cm³ 3 It is particularly preferable that this be the case. Furthermore, it is preferable that the crystal of the present invention has diffraction peaks at diffraction angles 2θ of 11.0±0.2°, 12.9±0.2°, 16.1±0.2°, 17.5±0.2°, and 22.2±0.2° in the powder X-ray diffraction peak pattern using Cu-Kα rays.

[0017] The crystalline material of the present invention is useful as a raw material for polyphenylene ether, epoxy resin, and polycarbonate resin. [Examples]

[0018] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The analytical method in this invention is as follows: <Analysis method> 1. Differential Scanning Calorimetry (DSC) 2.5 to 3.5 mg of the crystalline material was precisely weighed into an aluminum pan, sealed, and measured using a differential scanning calorimetry system (DSC7020, Hitachi High-Tech Science Co., Ltd.) with aluminum oxide as a control under the following operating conditions. (Operating conditions) Heating rate: 10℃ / min Measurement temperature range: 30~250℃ Measurement atmosphere: Nitrogen 50 mL / min 2. Loose bulk density The crystals are gently placed into a 5 mL graduated cylinder, ensuring no air pockets are created. The specific mark X (mL) on the graduated cylinder and the weight W (g) of the crystals in the cylinder at that time are then measured, and the W / X (g / cm³) ratio is calculated. 3 The value calculated by ) was defined as the "loose bulk density" in this invention. 3. Purity determined by high-performance liquid chromatography analysis The area percentage of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane in the sample measured using the following apparatus and under the following conditions was defined as the purity. Equipment: ProminenceUFLC (liquid chromatography) manufactured by Shimadzu Corporation Pump: LC-20AD Column Oven: CTO-20A Detector: SPD-20A Column: HALO C18 (inner diameter 3mm, length 75mm) Oven temperature: 50℃ Flow rate: 0.7mL / min Mobile phase: (A) 0.2 vol% aqueous acetic acid solution, (B) methanol Gradient conditions: (B) Volume % (Time from start of analysis) 20%(0min)→40%(10min)→60%(20min)→100%(30min)→100%(35min) Sample injection volume: 7 μL Detection wavelength: 280nm 4. Powder X-ray diffraction (XRD) measurement 0.1 g of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane crystals obtained in Example 2 were placed in the sample packing area of ​​a glass test plate and measured using the following apparatus and under the following conditions. Device: Rigaku Corporation MiniFlex600-C X-ray source:CuKα Scan axis: 2θ / θ Mode: Continuous Measurement range: 2θ = 5~90° Step: 0.02° Speed ​​measurement time: 10° / min Entrance slit: 0.25° Light-receiving slit: 13.00 mm Tube voltage: 40kV Tube current: 15mA

[0019] <Example 1> 56.3 g (460.9 mmol) of 2,6-dimethylphenol and 20.8 g of methanol were placed in a 500 mL four-necked flask. The mixture was heated to 40°C under a nitrogen atmosphere, and then hydrogen chloride gas was blown in until the system was saturated. While maintaining the reaction mixture temperature at 38-42°C, 8.4 g (25.2 mmol) of 21% sodium methyl mercaptan aqueous solution was added dropwise while stirring. Then, a solution of 52.0 g (425.5 mmol) of 2,6-dimethylphenol and 25.0 g (152.0 mmol) of 4-hydroxy-3,5-dimethylacetophenone, dissolved at 80°C, was added dropwise over 1 hour. After the addition was complete, the mixture was stirred for 16 hours at a reaction mixture temperature of 39-42°C while blowing in hydrogen chloride gas. After the reaction was complete, sodium hydroxide aqueous solution and phosphoric acid were added to adjust the pH to 5.2, and then the aqueous layer was separated and removed. Methanol and excess 2,6-dimethylphenol were removed from the obtained oil layer by vacuum distillation. The crude residue after distillation contained 68% by weight of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane and 28% by weight of 2,6-dimethylphenol. 14.5 g of the crude product remaining after distillation was dissolved in 30.0 g of toluene at 60°C, and the precipitated crystals were filtered after gradual cooling at 5°C / hour to 25°C. The obtained crystals were dried under reduced pressure by raising the temperature to 120°C to obtain 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane. The yield relative to 4-hydroxy-3,5-dimethylacetophenone was 16%, and the purity by high-performance liquid chromatography analysis was 90.5 area%. The maximum endothermic temperature of the obtained crystal, determined by differential scanning calorimetry, was 208.5°C, and the loose bulk density was 0.315 g / cm³. 3 That was the case. The DSC data of the obtained crystals is shown in Figure 1.

[0020] <Comparative Example 1> 267.9 g (2192.3 mmol) of 2,6-dimethylphenol and 136.9 g of methanol were placed in a 2 L four-necked flask. The mixture was heated to 40°C under a nitrogen atmosphere, and then hydrogen chloride gas was blown in until the system was saturated. While maintaining the reaction mixture temperature at 38-42°C, 36.0 g (103.2 mmol) of 21% sodium methyl mercaptan aqueous solution was added dropwise while stirring. Then, a solution of 645.0 g (5287.2 mmol) of 2,6-dimethylphenol and 120.0 g (730.8 mmol) of 4-hydroxy-3,5-dimethylacetophenone, dissolved at 80°C, was added dropwise over 1 hour. After the addition was complete, the mixture was stirred for 16 hours at a reaction mixture temperature of 39-42°C while blowing in hydrogen chloride gas. After the reaction was complete, sodium hydroxide aqueous solution and phosphoric acid were added to adjust the pH to 5.2, and then the aqueous layer was separated and removed. Methanol and excess 2,6-dimethylphenol were removed from the obtained oil layer by vacuum distillation. The crude residue after this distillation contained 31% by weight of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane and 52% by weight of 2,6-dimethylphenol. 412.9 g of the crude product remaining after distillation was dissolved in 300.0 g of toluene at 80°C, and the mixture was gradually cooled to 25°C at 5°C / hour. The precipitated solid was filtered. The obtained solid was dried under reduced pressure by raising the temperature to 120°C to obtain the solid content containing 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane. The purity of the obtained solid, as determined by high-performance liquid chromatography, was 67.0 area%. This crude product contained 80% by weight of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane and 11% by weight of 2,6-dimethylphenol.

[0021] <Example 2> 133.3 g of the crude product obtained by filtration and drying in Comparative Example 1 was dissolved in 450 g of toluene at 80°C, and the precipitated crystals were filtered off after being gradually cooled to 25°C at a rate of 5°C / hour. The obtained crystals were dried under reduced pressure by raising the temperature to 120°C to obtain 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane. The yield relative to the amount of 4-hydroxy-3,5-dimethylacetophenone used in Comparative Example 1 was 35.1%, and the purity determined by high-performance liquid chromatography was 96.4%. The maximum endothermic temperature of the obtained crystal, determined by differential scanning calorimetry, was 211.1°C. The DSC data of the obtained crystals is shown in Figure 2. The XRD measurement chart of the obtained crystal is shown in Figure 3. Table 1 below shows the diffraction angle 2θ(°) and relative intensity of the peaks with a relative intensity of 0.2 or higher, relative to the peak with the strongest intensity among the observed diffraction peaks.

[0022] [Table 1]

[0023] <Comparative Example 2> 55.0 g (450.1 mmol) of 2,6-dimethylphenol and 24.8 g of methanol were placed in a 1 L four-necked flask. The mixture was heated to 40°C under a nitrogen atmosphere, and then hydrogen chloride gas was blown in until the system was saturated. While maintaining the reaction mixture temperature at 38-42°C, 9.0 g (44.5 mmol) of lauryl mercaptan was added dropwise while stirring. Then, a solution of 110.0 g (900.2 mmol) of 2,6-dimethylphenol and 25.0 g (152.0 mmol) of 4-hydroxy-3,5-dimethylacetophenone, dissolved at 80°C, was added dropwise over 1 hour. After the addition was complete, the mixture was stirred for 16 hours at a reaction mixture temperature of 39-42°C while blowing in hydrogen chloride gas. After the reaction was complete, aqueous sodium hydroxide solution and phosphoric acid were added to adjust the pH to 5.2, and the aqueous layer was separated and removed. The resulting oil layer was divided into two parts. Methanol and 2,6-dimethylphenol were removed from one of the two separated oil layers by vacuum distillation. The crude product, 7.9 g, remaining after distillation, contained 37.2% by weight of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane and 44.8% by weight of 2,6-dimethylphenol. When a mixture of methyl isobutyl ketone and toluene (weight ratio 4:1) was added at a rate of 50% by weight relative to the weight of the obtained distillation residue, the entire amount dissolved, and no crystals formed even after standing at 25°C for 20 hours.

[0024] <Comparative Example 3> In Comparative Example 2, methanol and 2,6-dimethylphenol were removed from the other oil layer that had been divided into two by vacuum distillation. The crude product of 9.9 g remaining after distillation contained 38.9% by weight of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane and 42.1% by weight of 2,6-dimethylphenol. When 4 mL of dichloromethane was added to 1 g of the obtained distillation residue, the entire amount dissolved, and no crystals formed even after standing at 25°C for 20 hours.

[0025] <Solubility in organic solvents> The solubility (g) of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane in 100g of solvent was measured for the solvents listed in the table. The results are shown in Table 2. A "-" in the table indicates that the measurement was not performed. [Table 2]

[0026] As shown in Table 2, methanol, acetone, and methyl isobutyl ketone have higher solubility than toluene used in Examples 1 and 2, making them unsuitable for the crystallization of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane. On the other hand, toluene used in Examples 1 and 2 is preferable for crystallization because it exhibits a sufficient difference in the solubility of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane depending on the temperature, and its solubility at room temperature (25°C) is low. It was also found to be preferable because there is little loss of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane into the filtrate when the crystals are filtered off after the crystallization operation. Furthermore, xylene was also confirmed to be suitable as a solvent for crystallization of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane, similar to toluene.

Claims

1. A crystalline form of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane, with a maximum endothermic temperature measured by differential scanning calorimetry in the range of 195–225°C.

2. Loose bulk density is 0.25-0.6 g / cm³ ３ The crystalline material according to claim 1, which is within the range of [specify range].

3. The crystalline material according to claim 1 or 2, wherein the powder X-ray diffraction peak pattern using Cu-Kα rays has diffraction peaks at diffraction angles 2θ of 11.0±0.2°, 12.9±0.2°, 16.1±0.2°, 17.5±0.2°, and 22.2±0.2°.

4. A method for producing a crystal according to any one of claims 1 to 3, characterized by cooling a solution containing 100 parts by weight of 1,1,1-tris(4-hydroxy-3,5-dimethylphenyl)ethane and 250 to 1500 parts by weight of an aromatic hydrocarbon solvent to precipitate crystals.

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