Method for producing high-purity aromatic diol

Abstract

To provide a method for preparing a high-purity aromatic diol.SOLUTION: There is provided a method for producing a high-purity aromatic diol represented by the formula (1), which comprises a step of mixing a crude composition containing an aromatic diol represented by the formula (1) [wherein, Ar1 and Ar2 each individually represents a divalent aromatic group] and an alcohol aqueous solution having a concentration of 35 to 95 mass%, followed by mixing the obtained suspension, wherein the sulfur atom content contained in the crude composition containing the aromatic diol represented by the formula (1) is 200 ppm or more and the sulfur atom content contained in the high-purity aromatic diol represented by the formula (1) is less than 200 ppm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a high-purity aromatic diol. [Background technology]

[0002] Aromatic diols having an ester group in the molecule are used as structural units of various resins, including polyesters (Patent Documents 1 and 2). In particular, in recent years, it has been reported that the cured products of thermosetting resin compositions obtained by mixing aromatic diols with epoxy resins have excellent thermal conductivity (Patent Document 3), and they are expected to be used in applications such as encapsulants for semiconductor devices and heat dissipation insulating materials such as heat dissipation insulating substrates and sheets.

[0003] As a method for producing an aromatic diol having an ester group in the molecule, there have been proposed a method for producing 4-hydroxyphenyl 4-hydroxybenzoate by reacting p-hydroxybenzoic acid with hydroquinone using an esterification catalyst in a reaction solvent in which the reactants are substantially dispersed (Patent Document 4), and a method for producing a diphenol compound characterized by a step of dehydration condensation of 6-hydroxy-2-naphthoic acid with hydroquinone in the presence of sulfuric acid and phosphoric acid (Patent Document 5). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-049733 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-113511 [Patent Document 3] Patent Publication No. 2021-183683 [Patent Document 4] Japanese Patent Application Publication No. 63-022540 [Patent Document 5] Japanese Patent Application Laid-Open No. 2012-201603 Summary of the Invention [Problem to be solved by the invention]

[0005] However, diols produced by such esterification contain residual esterification catalysts such as sulfuric acid, and therefore, for use as polymer materials, diols of higher purity are required. [Means for solving the problem]

[0006] In view of the above problems, the present inventors have conducted extensive research and have found that a high-purity aromatic diol can be prepared by stirring a crude composition containing an aromatic diol in a suspended state in the presence of a 35 to 95 mass % aqueous alcohol solution, thereby completing the present invention.

[0007] That is, the present invention includes the following preferred embodiments. [1] Formula (1) [ka] [In the formula, Ar1 and Ar2 each represent a divalent aromatic group.] a crude composition containing an aromatic diol represented by formula (1) and an aqueous alcohol solution having a concentration of 35 to 95 mass %, and stirring the resulting suspension, The method, wherein the content of sulfur atoms contained in the crude composition containing the aromatic diol represented by formula (1) is 200 ppm or more, and the content of sulfur atoms contained in the high-purity aromatic diol represented by formula (1) is less than 200 ppm. [2] Ar1 and Ar2 are each independently represented by the formulas (I) to (III) [ka] [In the formula, "-*" indicates the bonding position of the aromatic group] The method according to [1], wherein the aromatic group is selected from aromatic groups represented by the formula: [3] The method according to [2], wherein Ar1 and Ar2 are both aromatic groups represented by formula (I). [4] A crude composition containing an aromatic diol represented by formula (1) is reacted with a compound represented by formula (2) in an organic solvent in the presence of a sulfur-containing acid catalyst. [ka] and a compound represented by formula (3) [ka] The method according to any one of [1] to [3], wherein the compound is obtained by reacting a compound represented by the formula: [5] The method according to [4], wherein the organic solvent is at least one selected from the group consisting of toluene, xylene, anisole, mesitylene, and 4-methyltetrahydropyran. [6] The method according to [4] or [5], wherein the sulfur-containing acid catalyst is at least one selected from the group consisting of sulfuric acid, sulfurous acid, dimethyl sulfate, diethyl sulfate, chlorosulfonic acid, fluorosulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid. [7] The method according to any one of [1] to [6], wherein the alcohol is at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutyl alcohol, 2-butanol, 2-ethyl-2-propanol, 2-ethylhexanol, and 2-ethoxyethanol. [8] The method according to [7], wherein the alcohol is methanol. [9] The method according to any one of [1] to [8], wherein the suspension is stirred in the presence of 200 to 2000 parts by mass of the aqueous alcohol solution relative to 100 parts by mass of the aromatic diol represented by formula (1) in the crude composition.

[10] The production method according to any one of [1] to [9], wherein the suspension is stirred at a temperature of 30 to 70°C.

[11] The content of sulfur atoms is 1 ppm or more and less than 200 ppm, [ka] [In the formula, Ar1 and Ar2 each represent a divalent aromatic group.] A high-purity aromatic diol represented by the formula:

[12] Ar1 and Ar2 are each independently represented by the formula (I) to (III) [ka] [In the formula, "-*" indicates the bonding position of the aromatic group] The high-purity aromatic diol according to

[11] , wherein the aromatic group is selected from aromatic groups represented by the following formula:

[13] The high-purity aromatic diol according to

[12] , wherein Ar1 and Ar2 are both aromatic groups represented by formula (I). [Effects of the Invention]

[0008] According to the present invention, a high-purity aromatic diol represented by formula (1) can be obtained which has a low content of sulfur atoms derived from the sulfur-containing acid catalyst used in synthesizing the target aromatic diol. DETAILED DESCRIPTION OF THE INVENTION

[0009] The production method of the present invention relates to a method for producing a high-purity aromatic diol represented by formula (1), which comprises the steps of mixing a crude composition containing the aromatic diol represented by formula (1) with an aqueous alcohol solution having a concentration of 35 to 95 mass%, and stirring the resulting suspension. [ka] [In the formula, Ar1 and Ar2 each represent a divalent aromatic group.]

[0010] In formula (1), Ar1 and Ar2 are preferably each independently selected from the aromatic groups represented by formulae (I) to (III). [ka] [In the formula, "-*" indicates the bonding position of the aromatic group.]

[0011] An example of the aromatic diol represented by formula (1) is a compound represented by the following formula (1)-1 (hereinafter referred to as HQ-POB) in which both Ar1 and Ar2 are aromatic groups of formula (I). [ka]

[0012] Examples of aromatic diols represented by formula (1) include compounds in which Ar1 is an aromatic group of formula (II) and Ar2 is an aromatic group of formula (I), that is, compounds represented by the following formula (1)-2. [ka]

[0013] In the present invention, the term "crude composition containing an aromatic diol represented by formula (1)" refers to a composition containing impurities such as reaction raw materials, catalysts, and reaction by-products in addition to the target aromatic diol represented by formula (1), and is a composition having a sulfur atom content of 200 ppm or more. The sulfur atom content is 5,000 ppm or more in one embodiment and 2,000 ppm or more in another embodiment. The sulfur atom content is typically 10,000 ppm or less. The impurity content varies depending on the reaction method, but is typically 1 to 70 mass% of the crude composition, and in another embodiment, 5 to 50 mass%. Furthermore, the term "high-purity aromatic diol represented by formula (1)" refers to an aromatic diol represented by formula (1) having a sulfur atom content of less than 200 ppm. The sulfur atom content in the high-purity aromatic diol is preferably 500 ppm or less, more preferably 300 ppm or less, and even more preferably 200 ppm or less. The sulfur atom content in the high-purity aromatic diol according to the present invention is typically 1 ppm or more.

[0014] In this specification, a crude composition containing HQ-POB is also simply referred to as "crude HQ-POB."

[0015] The crude composition containing the aromatic diol represented by formula (1) used in the present invention is preferably one obtained by reacting a compound represented by formula (2) with a compound represented by formula (3) in an organic solvent in the presence of a sulfur-containing acid catalyst. Alternatively, a commercially available crude composition containing the aromatic diol represented by formula (1) having a sulfur atom content of 200 ppm or more may be used. Note that Ar1 and Ar2 in formulas (2) and (3) are the same aromatic groups as Ar1 and Ar2 in formula (1). [ka] [ka]

[0016] In the method for obtaining a crude composition containing an aromatic diol represented by the above formula (1), the sulfur-containing acid catalyst refers to an acid catalyst containing a sulfur atom in the molecule, and examples thereof include one or more selected from the group consisting of sulfuric acid, sulfurous acid, dimethyl sulfate, diethyl sulfate, chlorosulfonic acid, fluorosulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid, with sulfuric acid being preferred in terms of its excellent reactivity.

[0017] In the method for obtaining a crude composition containing an aromatic diol represented by the above formula (1), the organic solvent may be at least one selected from the group consisting of toluene, xylene, anisole, mesitylene, and 4-methyltetrahydropyran, and toluene is preferred in terms of its excellent reactivity.

[0018] In the method for obtaining a crude composition containing an aromatic diol represented by the above formula (1), the amount of the organic solvent used is 0.5 times or more by mass, preferably 1 to 20 times by mass, and more preferably 5 to 15 times by mass, relative to the amount of the compound represented by formula (2).

[0019] The reaction temperature of the compound represented by formula (2) and the compound represented by formula (3) is usually 50 to 150° C., preferably 80 to 120° C., and more preferably 100 to 110° C. If the temperature is lower than 50° C., the reaction will not proceed, and if the temperature is higher than 150° C., the reaction will plateau, resulting in a loss of energy and the risk of side reactions occurring.

[0020] The reaction time is usually from several minutes to 30 hours, and can be appropriately selected from the range of preferably 1 to 20 hours, more preferably 4 to 16 hours, and particularly preferably 8 to 12 hours.

[0021] The reaction is preferably carried out under an atmosphere of an inert gas such as nitrogen or helium.

[0022] The reaction solution containing the aromatic diol obtained by the reaction is subjected to solid-liquid separation by a conventional means such as filtration, and a crude composition containing the aromatic diol used in the present invention is recovered. After solid-liquid separation, it is preferable to wash the crystals by pouring fresh solvent onto the solid on the filter cloth or filter paper and then subjecting it to solid-liquid separation again.

[0023] The crude composition containing the aromatic diol represented by formula (1) thus obtained is subjected to the production method of the present invention.

[0024] The alcohol used in the production method of the present invention may be one or more selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutyl alcohol, 2-butanol, 2-ethyl-2-propanol, 2-ethylhexanol, and 2-ethoxyethanol, and methanol is preferred because of its excellent purification effect.

[0025] The concentration (alcohol concentration) of the aqueous alcohol solution used in the production method of the present invention is 35 to 95 mass %, preferably 40 to 90 mass %, and particularly preferably 45 to 85 mass %. When the concentration of the aqueous alcohol solution is within the above range, sulfur atom-containing compounds, which are impurities, can be efficiently removed.

[0026] The amount of aqueous alcohol solution used is preferably 200 to 2000 parts by mass per 100 parts by mass of the aromatic diol represented by formula (1) in the crude composition. If the amount of aqueous alcohol solution used is less than 200 parts by mass per 100 parts by mass of aromatic diol, the effect of removing sulfur atoms may be reduced. On the other hand, if the amount of aqueous alcohol solution used is more than 2000 parts by mass per 100 parts by mass of aromatic diol, the excess aqueous alcohol solution may be wasted, resulting in reduced production efficiency.

[0027] The temperature of the suspension during stirring is preferably 30 to 70°C, more preferably 40 to 65°C, and even more preferably 50 to 60°C.

[0028] If the temperature during stirring of the suspension is less than 30°C, the effect of removing sulfur atoms tends to decrease, and if it exceeds 70°C, the crude product may react with methanol, causing the by-production of impurities.

[0029] The stirring time of the suspension is preferably 10 to 500 minutes, more preferably 30 to 360 minutes. If the stirring time is less than 10 minutes, the effect of removing sulfur atoms from the aromatic diol crystals may decrease. If the stirring time is more than 500 minutes, the purification efficiency may reach a plateau, resulting in energy loss and the generation of by-products.

[0030] In the present invention, a suspension refers to a liquid in which all or part of the crude composition is dispersed as a solid in an aqueous alcohol solution, which serves as a dispersing medium. Since the crude composition in the suspension is preferably in the form of fine particles, the fine particle crude composition is subjected to washing. The average particle size of the crude composition subjected to washing is preferably 10 to 150 nm, more preferably 20 to 100 nm. The average particle size of the crude composition can be measured, for example, using a particle size distribution analyzer MT3200 manufactured by Microtrac-Bell. For example, a device equipped with a rotating shaft and stirring blades, or a magnetic stirrer, can be used as a stirring method.

[0031] The aromatic diol slurry (suspension) obtained by the production method of the present invention is separated and recovered from the slurry by conventional means such as centrifugation, filtration with a filter press, etc. The recovered aromatic diol crystals are washed with cold water, hot water, an aqueous alcohol solution, etc., as necessary, and then dried.

[0032] The high purity aromatic diol thus obtained is suitable for use as a raw material for preparing various polymers.

[0033] The content of sulfur atoms contained in the high-purity aromatic diol obtained by the method of the present invention is less than 200 ppm. The content of sulfur atoms is preferably less than 150 ppm, more preferably less than 100 ppm, and even more preferably less than 50 ppm. The content of sulfur atoms contained in the high-purity aromatic diol obtained by the method of the present invention is usually 1 ppm or more, and in other cases 10 ppm or more. Such sulfur atoms are derived from sulfuric acid, p-toluenesulfonic acid, or the like used as a sulfur-containing acid catalyst during the synthesis of the aromatic diol represented by formula (1).

[0034] The content of sulfur atoms is measured by oxidative decomposition-coulometric titration method.

[0035] Thus, the present invention provides a high-purity aromatic diol represented by formula (1) having a sulfur atom content of 1 ppm or more and less than 200 ppm, preferably less than 150 ppm, more preferably less than 100 ppm, and even more preferably less than 50 ppm. [ka] [In the formula, Ar1 and Ar2 each represent a divalent aromatic group.] [Example]

[0036] The present invention will be described in detail below with reference to examples, but these examples are not intended to limit the scope of the present invention. The target aromatic diol represented by formula (1) was analyzed by the following method.

[0037] [High-Performance Liquid Chromatography (HPLC)]: (Measurement of Purity of Aromatic Diols) Instrument: Waters Alliance 2690 / 2996 Column model number: L-Column Fluid volume: 1.0mL / min Solvent ratio: HO (pH 2.3) / MeOH = 60 / 40 (20 min) → 15 min → 10 / 90 (→ 5 / 95 (9 min), gradient analysis Wavelength: 229nm Column temperature: 40℃

[0038] [Gas Chromatography (GC)]: (Measurement of Toluene and Methanol Content in Aromatic Diols) Equipment: Shimadzu Corporation GC-2014 (G-2) Column model number: TC-WAX 0.32mm x 30m 0.25μm Injection volume: 1.0μL Oven temperature: 300°C Internal standard: n-propylbenzene Carrier gas: Helium Detector: FID

[0039] [Oxidative decomposition - coulometric titration]: (Measurement of sulfur atom content in aromatic diols) Equipment: Mitsubishi Chemical Analytech TOX-2100H Temperature: 900℃ Gases used: oxygen, argon

[0040] [Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP)]: (Measurement of the sodium and potassium atom content in aromatic diols) Instrument: Thermo Scientific iCAP 6000 Sample introduction: Direct High frequency power: 1250W Plasma gas flow rate: 13.0L / min Nebulizer gas flow rate: 0.22L / min

[0041] <Yield measurement> The yield was determined by the following formula: Yield (%) = 100 - elution rate of HQ-POB into mother liquor and washings

[0042] <Measurement of average particle size> 0.005 g of crude HQ-POB, 0.05 g of 0.1% Triton X aqueous solution, and 0.01 g of water were mixed and stirred for 10 minutes using a magnetic stirrer. After stirring, the particle size distribution was measured using a Microtrac-Bell MT3200 particle size distribution analyzer.

[0043] Reference Example 1 (Preparation of crude HQ-POB) A 1L four-neck flask equipped with a stirrer and a temperature sensor was charged with 63g (0.46mol) of 4-hydroxybenzoic acid, 50g (0.46mol) of hydroquinone, 630g of toluene, and 2g (0.02mol) of concentrated sulfuric acid as a reaction catalyst. The atmosphere was purged with nitrogen, and the suspension was heated with stirring and refluxed for 10 hours while dehydrating. The suspension was cooled to 30°C, then solid-liquid separated and washed with 190g of methanol to obtain 160g of solid.

[0044] The resulting solid was dried under reduced pressure for 5 hours and quantitatively analyzed by HPLC, GC, oxidative decomposition-coulometric titration, and ICP (the solid contained 80 g of HQ-POB). The results are shown in Table 1. The average particle size was measured and found to be 72 nm.

[0045] [Example 1] A 1-L four-neck flask equipped with a stirrer and temperature sensor was charged with 160 g of the solid obtained in Reference Example 1 and 480 g of 70% aqueous methanol (600 parts by weight relative to 100 parts by weight of HQ-POB contained in the solid). The atmosphere was then purged with nitrogen. The resulting suspension was heated to 60°C with stirring and maintained at that temperature for 1 hour. The suspension was cooled to 20°C, subjected to solid-liquid separation, and then washed with 160 g of water (200 parts by weight relative to 100 parts by weight of HQ-POB contained in the solid). The resulting HQ-POB crystals were dried at 80°C for 15 hours to yield 74 g of HQ-POB. Quantitative analysis was performed using HPLC, GC, oxidative decomposition-coulometric titration, and ICP. The results are shown in Table 1.

[0046] [Examples 2 to 4, Comparative Examples 1 and 2] Aromatic diols were obtained in the same manner as in Example 1, except that the solvents were changed to those shown in Table 1. The obtained aromatic diols were quantitatively analyzed by HPLC, oxidative decomposition-coulometric titration, and ICP. The results are shown in Table 1.

[0047] As shown in Table 1, Examples 1 to 4 of the present invention were able to significantly reduce the content of sulfur atoms compared to Comparative Examples 1 and 2.

[0048] [Table 1]

Claims

1. Formula (1) 【Chemistry 1】 [In the formula, Ar １ and Ar ２ each represents a divalent aromatic group. a crude composition containing an aromatic diol represented by formula (1) and an aqueous alcohol solution having a concentration of 35 to 95 mass%, and stirring the resulting suspension, The method of claim 1, wherein the crude composition containing the aromatic diol represented by formula (1) has a sulfur atom content of 200 ppm or more, and the high-purity aromatic diol represented by formula (1) has a sulfur atom content of less than 200 ppm.

2. Ar １ and Ar ２ are each independently of one another represented by the formulas (I) to (III) 【Chemistry 2】 [In the formula, "-*" indicates the bonding position of the aromatic group] The method of claim 1, wherein the aromatic group is selected from aromatic groups represented by the formula:

3. Ar １ and Ar ２ and are both aromatic groups represented by formula (I).

4. The crude composition containing the aromatic diol represented by formula (1) is reacted with a compound represented by formula (2) in an organic solvent in the presence of a sulfur-containing acid catalyst. 【Transformation 3】 and a compound represented by formula (3) 【Chemistry 4】 The method according to claim 1, wherein the compound is obtained by reacting a compound represented by the formula:

5. 5. The method according to claim 4, wherein the organic solvent is at least one selected from the group consisting of toluene, xylene, anisole, mesitylene, and 4-methyltetrahydropyran.

6. The method according to claim 4, wherein the sulfur-containing acid catalyst is at least one selected from the group consisting of sulfuric acid, sulfurous acid, dimethyl sulfate, diethyl sulfate, chlorosulfonic acid, fluorosulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid.

7. 2. The method according to claim 1, wherein the alcohol is at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutyl alcohol, 2-butanol, 2-ethyl-2-propanol, 2-ethylhexanol, and 2-ethoxyethanol.

8. 8. The method of claim 7, wherein the alcohol is methanol.

9. The method according to claim 1, wherein the suspension is stirred in the presence of 200 to 2,000 parts by mass of the aqueous alcohol solution relative to 100 parts by mass of the aromatic diol represented by formula (1) in the crude composition.

10. The method according to claim 1, wherein the suspension is stirred at a temperature of 30 to 70°C.

11. The sulfur atom content is 1 ppm or more and less than 200 ppm, 【Transformation 5】 [In the formula, Ar １ and Ar ２ each represents a divalent aromatic group. A high-purity aromatic diol represented by the formula:

12. Ar １ and Ar ２ are each independently of one another represented by the formulas (I) to (III) 【Transformation 6】 [In the formula, "-*" indicates the bonding position of the aromatic group] The high purity aromatic diol according to claim 11, wherein the aromatic group is selected from aromatic groups represented by the formula:

13. Ar １ and Ar ２ and are both aromatic groups represented by formula (I).

Images