A method for preparing 1,2-bis(4′-hydroxyphenyl)ethane

Abstract

The invention relates to a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane, and belongs to the technical field of organic chemistry. Phenol and an organic solvent are added into a reactor, and glyoxal and a hindered Lewis acid-base pair are added for reaction to obtain 1,2-bis(4′-hydroxyphenyl)ethane with high yield and high purity. Compared with other catalysts, the hindered Lewis acid-base pair (FLP) used in the invention has more advantages, and the catalyst can be recovered, thereby reducing the cost.

Description

Technical Field

[0001] The invention relates to the technical field of organic chemistry, in particular to a method for preparing 1,2-bis(4'-hydroxyphenyl)ethane. Background Art

[0002] 1,2-bis(4′-hydroxyphenyl)ethane is a precursor of electronic materials. It has four benzene rings and four symmetrical hydroxyl groups that can be linked to different groups for modification to form electronic resin materials with different functions: For example: E1035

[0003] .

[0004] It not only has the characteristics of high epoxy value, high softening point, good mechanical properties and heat resistance, but also has the UV shielding function and fluorescence generation function that ordinary epoxy molding materials cannot do. Therefore, it is used in the fields of bonding electronic components, glass reinforced fiber plastic structures, etc.

[0005] At present, the synthesis of 1,2-bis(4′-hydroxyphenyl)ethane and its homologues mainly uses phenol and glyoxal as raw materials. The cation exchange resin and ionic liquid catalysis either have unsatisfactory reactions or complicated post-processing. When strong acids such as sulfuric acid are used directly as catalysts, they cause serious corrosion to the equipment. There are various limitations in the process of amplification.

[0006] Hindered Lewis acid-base pair (FLP) refers to the phenomenon that the interaction between Lewis acid and Lewis base with certain steric hindrance can activate hydrogen and various small molecules. Because its activation conditions are mild and do not even require the participation of metals, it is currently a cutting-edge research topic in the field of chemistry. Due to widespread attention, FLP catalysts have achieved rapid development in recent years. Its composition sources cover almost the entire periodic table, and the reaction types have also expanded from the initial activation of small molecules such as hydrogen and carbon dioxide to the activation of carbon-hydrogen bonds of a wide range of substrates and asymmetric catalysis. The reaction modes also include thermal catalysis, photocatalysis and electrocatalysis.

[0007] Journal of Beijing University of Chemical Technology (Natural Science Edition), 2012, 39(06): 42-46 The synthesis of tetraphenol ethane from phenol and glyoxal using ion exchange resin as catalyst was systematically reported. The reaction conditions were analyzed by high performance liquid chromatography coupled with mass spectrometry. When the molar ratio of phenol to glyoxal was 15:1 and the reaction time was 32 h, the highest liquid phase yield of 78.8% was obtained. The purity data of the pure product was not reported. The reaction equation of the specific reaction is as follows:

[0008] .

[0009] Patent CN116354796 reports a method for synthesizing tetraphenolethane from phenol and ethylene glycol at 100-140°C using ionic liquid as a catalyst, achieving a yield of up to 90% with a feed of 100 kg, but no purity data is provided. The use of ionic liquids adds subsequent steps such as toluene extraction, liquid separation, dehydration and drying to recover the ionic liquid; under high temperature reaction conditions above 100°C, phenols will undergo intermolecular dehydration to form ethers; during the process of distilling phenol from the toluene solution, phenols will also undergo intermolecular dehydration to form ethers, reducing the purity of the product. The reaction equation for the specific reaction is shown below:

[0010] .

[0011] Moreover, in the prior art, catalysts such as ion exchange resins and ionic liquids need to be recovered and reactivated; and the excess of raw materials makes it difficult to purify the product. Therefore, it is urgent to provide a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane with high yield and purity and reusable catalysts. Summary of the invention

[0012] In order to solve the above technical problems, the present invention provides a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane. In the present invention, phenol and an organic solvent are added to a reaction kettle, and glyoxal and a hindered Lewis acid-base pair are added to react to obtain 1,2-bis(4′-hydroxyphenyl)ethane with high yield and high purity. The hindered Lewis acid-base pair (FLP) used in the present invention can be recycled and reused, thereby reducing the preparation cost.

[0013] The present invention is achieved through the following technical solutions:

[0014] The object of the present invention is to provide a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane, comprising the following steps:

[0015] Phenol and an organic solvent are added into a reaction kettle, and p-glyoxal and a hindered Lewis acid-base pair are added to react to obtain 1,2-bis(4′-hydroxyphenyl)ethane.

[0016] In one embodiment of the present invention, the organic solvent is selected from one or more of acetonitrile, DMSO and DMF.

[0017] In one embodiment of the present invention, the mass of the organic solvent is 10%-50% of phenol; preferably 15%-20%.

[0018] In one embodiment of the present invention, the molar ratio of phenol to glyoxal is 4:1-20:1, preferably 4.2:1.

[0019] In one embodiment of the present invention, the structural formula of the hindered Lewis acid-base pair is:

[0020] .

[0021] In one embodiment of the present invention, the added amount of the hindered Lewis acid-base pair is 0.5%-1.0% equivalent.

[0022] In one embodiment of the present invention, the reaction temperature is 20°C-25°C; and the reaction time is 10h-16h.

[0023] In one embodiment of the present invention, the reaction further comprises the steps of adding water, stirring, crystallization, filtering and drying.

[0024] In one embodiment of the present invention, the yield of 1,2-bis(4′-hydroxyphenyl)ethane is greater than 87%.

[0025] In one embodiment of the present invention, the purity of the 1,2-bis(4′-hydroxyphenyl)ethane is above 99.6%.

[0026] The present invention provides a 1,2-bis(4′-hydroxyphenyl)ethane compound, the structure of which is as follows:

[0027] .

[0028] In one embodiment of the present invention, the specific preparation scheme of the 1,2-bis(4′-hydroxyphenyl)ethane compound is as follows:

[0029] (1) Phenol and acetonitrile are added into a reaction kettle, followed by terephthalaldehyde and hindered Lewis acid-base pair (FLP), and then the mixture is kept warm for reaction, and water is added for crystallization and filtration to obtain pure 1,4-di[bis(4′-hydroxyphenyl)methyl]benzene and a mother liquor containing (FLP);

[0030] (2) The mother liquor can be recovered by alkali washing, water washing, and concentrated crystallization to obtain the hindered Lewis acid-base pair (FLP).

[0031] In step (2), the alkaline washing is to add an alkaline solution of a certain volume ratio, stir for a period of time, and then separate the liquids. The certain volume ratio refers to the volume ratio of the alkaline solution to the mother liquor being 0.1-0.5:1, and the stirring period is 10 min-2 h; the alkaline solution is saturated NaHCO3, saturated Na2CO3, 0.02 M-0.2 M NaOH solution, 0.02 M-0.2 M KOH solution, etc.

[0032] The above technical solution of the present invention has the following advantages compared with the prior art:

[0033] The present invention provides a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane. The present invention uses a hindered Lewis acid-base pair (FLP) as a catalyst to catalyze the reaction of phenol and glyoxal to obtain 1,2-bis(4′-hydroxyphenyl)ethane with a yield of 95.9% and a purity of 99.6% or more. Compared with other catalysts, the hindered Lewis acid-base pair (FLP) used in the present invention has more advantages, and the catalyst can be recovered, thereby reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0035] Figure 1 is the NMR image of 1,2-bis(4′-hydroxyphenyl)ethane in Example 2 of the present invention;

[0036] Figure 2 This is the liquid phase diagram of 1,2-bis(4′-hydroxyphenyl)ethane in Example 2 of the present invention. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0038] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0039] The synthesis of hindered Lewis acid-base pairs (FLPs) can be found in J. Am. Chem. Soc. 2020, 142, 34,14427–14431. The synthesis route is as follows:

[0040]

[0041] The CAS numbers of the reagents used in the present invention are shown in the table below:

[0042] Table 1

[0043] Example 1

[0044] This embodiment provides a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane, which is as follows:

[0045] Phenol (1.56 kg, 16.54 mol, 4 eq), acetonitrile (1500 mL), and hindered Lewis acid-base pair (FLP) (10.8 g, 20.68 mmol, 0.5% eq) were added to a four-necked flask. At room temperature, an aqueous solution of glyoxal (800 g, 4.14 mol, 30%, 1 eq) was added dropwise. The addition was completed over 30 min and the mixture was kept at 25°C for 10 h. The reaction was complete after HPLC detection. 9000 mL of purified water was added dropwise and stirred for 3 h. The crystals were filtered and dried to obtain 1.58 kg of pure 1,2-bis(4′-hydroxyphenyl)ethane and a mother liquor containing (FLP). The obtained pure 1,2-bis(4′-hydroxyphenyl)ethane was characterized by NMR and detected by HPLC. The NMR spectrum is shown in Figure 1 As shown in the HPLC diagram Figure 2 As shown; the yield is 95.9% and the purity is 99.6%. The obtained mother liquor is extracted with dichloromethane, concentrated and then recrystallized with n-hexane to recover the hindered Lewis acid-base pair (FLP).

[0046] NMR data: H NMR (DMSO): δ 8.92 (s, 2H), 7.06 (m, 4H), 6.45 (m, 4H), 4.64 (s, 1H). Example 2

[0047] This embodiment provides a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane, which is as follows:

[0048] Phenol (156 g, 1.654 mol, 6 eq), DMSO (150 mL), and hindered Lewis acid-base pair (FLP) (2.16 g, 4.14 mmol, 1% eq) were added to a four-necked flask. At room temperature, glyoxal aqueous solution (80 g, 41.4 mmol, 30%, 1 eq) was added dropwise, and the addition was completed in 30 min. The mixture was kept at 25°C for 14 h. The reaction was complete after HPLC detection, and 900 mL of purified water was added dropwise, and the mixture was stirred for 3 h. The crystals were filtered and dried to obtain 143 g of pure 1,2-di(4′-hydroxyphenyl)ethane and a mother liquor containing (FLP), with a yield of 87.0% and a purity of 99.7%. The obtained mother liquor was extracted with dichloromethane, concentrated, and recrystallized with n-hexane to recover the hindered Lewis acid-base pair (FLP). Example 3

[0049] This embodiment provides a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane, which is as follows:

[0050] Phenol (234 g, 2.481 mol, 4 eq), DMF (150 mL), and hindered Lewis acid-base pair (FLP) (1.08 g, 2.07 mmol, 0.5% eq) were added to a four-necked flask. At room temperature, an aqueous solution of glyoxal (80 g, 41.4 mmol, 30%, 1 eq) was added dropwise, and the addition was completed in 30 min. The mixture was kept at 25°C for 14 h. The reaction was complete after HPLC detection, and 900 mL of purified water was added dropwise, and the mixture was stirred for 3 h. The crystals were filtered and dried to obtain 143 g of pure 1,2-di(4′-hydroxyphenyl)ethane and a mother liquor containing (FLP), with a yield of 90.3% and a purity of 99.7%. The obtained mother liquor was extracted with dichloromethane, concentrated, and recrystallized with n-hexane to recover the hindered Lewis acid-base pair (FLP). Comparative Example 1

[0051] This comparative example provides a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane, which is similar to Example 1, except that:

[0052] The organic solvent acetonitrile was replaced by methanol, and the rest was the same as in Example 1. The yield was 23%, and after extraction, water washing, and crystallization purification, the purity was 81.5%, containing unreacted phenol. Comparative Example 2

[0053] This comparative example provides a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane, which is similar to Example 1, except that:

[0054] The organic solvent acetonitrile was replaced by dioxane, and the other steps were the same as in Example 1. The yield was 31%, and after extraction, water washing, and crystallization purification, the purity was 61.1%, containing unreacted phenol. Comparative Example 3

[0055] This comparative example provides a method for preparing 1,2-bis(4′-hydroxyphenyl)ethane, which is similar to that of Example 1, except that the catalyst used is concentrated sulfuric acid; the yield of the obtained product is 45.1% and the purity is 91.3%.

[0056] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for preparing 1,2-bis(4′-hydroxyphenyl)ethane, characterized in that: The following steps are involved: Phenol and an organic solvent are added into a reaction kettle, and p-glyoxal and a hindered Lewis acid-base pair are added to react to obtain 1,2-bis(4′-hydroxyphenyl)ethane; The structural formula of the hindered Lewis acid-base pair is: 。 2. The preparation method according to claim 1, characterized in that: The organic solvent is selected from one or more of acetonitrile, DMSO and DMF.

3. The preparation method according to claim 1, characterized in that: The mass of the organic solvent is 10%-50% of phenol.

4. The preparation method according to claim 1, characterized in that: The molar ratio of the phenol to glyoxal is 4:1-20:

1.

5. The preparation method according to claim 1, characterized in that: The added amount of the hindered Lewis acid-base pair is 0.5%-1.0% equivalent.

6. The preparation method according to claim 1, characterized in that: The reaction temperature is 20°C-25°C; the reaction time is 10 h-16 h.

7. The preparation method according to claim 1, characterized in that: After the reaction, the method further comprises the steps of adding water, stirring, crystallization, filtering and drying.

8. The preparation method according to claim 1, characterized in that: The yield of the 1,2-bis(4′-hydroxyphenyl)ethane is above 87%.

9. The preparation method according to claim 1, characterized in that: The purity of the 1,2-bis(4′-hydroxyphenyl)ethane is above 99.6%.

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