Method for synthesizing biphenol in water phase

Abstract

The invention discloses a method for synthesizing biphenol in a water phase, belongs to the technical field of fine chemical engineering, and aims to solve the explosion safety risk caused by the use of an organic solvent in the conventional alkylphenol oxidative coupling process. According to the method, a phase transfer catalysis system composed of boric acid, Tween-80, dodecylphenol polyoxyethylene ether and copper chloride is adopted, water serves as a solvent, oxygen or air is introduced at the temperature of 60-90 DEG C, alkyl phenol is subjected to an oxidative coupling reaction to generate alkyl biquinone, and then biphenol is prepared through hydrogenation reduction. The method thoroughly avoids the use of an organic solvent, eliminates the hidden danger of explosion from the source, and has the advantages of high intrinsic safety, environmental friendliness and low cost.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, and more specifically, to a method for the aqueous synthesis of biphenyl hydroquinone. Background Technology

[0002] Bisphenol is an important fine chemical intermediate. Due to the active phenolic hydroxyl groups at both ends, it can polymerize with diacids such as terephthalic acid to form liquid crystal polymers (LCPs), high-performance epoxy resins, polyesters, etc., which are widely used in the fields of electronics, aerospace, automotive industry and high-end composite materials.

[0003] Traditional biphenyl hydroquinone production processes mainly include the following routes (such as...) Figure 2 (as shown)

[0004] (a) Using benzidine as a raw material, diazonium salt is obtained by diazotization with NaNO2, followed by hydrolysis under acidic conditions to obtain biphenyl hydrophenol. This route has problems such as expensive raw materials, large amount of saline wastewater, and instability of diazonium salt;

[0005] (b) Using biphenyl as a raw material, biphenyl disulfonic acid is obtained by sulfonation with sulfuric acid, followed by high-temperature alkaline fusion with NaOH to obtain sodium biphenyl diphenol, and then neutralization with acid to obtain biphenyl diphenol. This route uses sulfonation and alkaline fusion, which has disadvantages such as poor selectivity of sulfonation reaction, large amount of tar by-products of high-temperature alkaline fusion, and a huge amount of waste. It has been gradually phased out.

[0006] (c) Using biphenyl as a raw material, dibromobiphenyl is obtained by bromination with bromine, followed by high-temperature debromination with NaOH to obtain sodium biphenylacetate, and then neutralization with acid to obtain biphenylacetate. This route has problems such as high bromine price, poor selectivity of bromination reaction, prominent safety issues, and large amount of saline wastewater.

[0007] Patent CN119954629A reports the use of alkylphenol as a raw material (such as...) Figure 3As shown in the figure, a method for preparing alkylbiphenyl diquinone by oxidative coupling of alkylphenols using modified chitosan-supported copper-based complexes as catalysts is employed, with ethyl acetate as the solvent. Since the oxidative coupling reaction uses oxygen as the oxidant, oxygen and ethyl acetate can easily form an explosive mixture, posing a significant safety hazard to this process. Because alkylphenols have poor solubility in water, methods for preparing biphenyl diquinone from alkylphenols generally require the use of organic solvents in the oxidation reaction, and the formation of explosive mixtures is a common problem in current methods. For example, patent CN119241335A reports a method for catalytic oxidation using alkylphenol as a raw material and a basic compound as a catalyst, but the reaction requires ethanol as a solvent; patent CN118459319A reports a method for catalytic oxidation using alkylphenol as a raw material and copper oxide as a catalyst, but the reaction requires acetone as a solvent; patent CN117776875A reports a method for catalytic oxidation using alkylphenol as a raw material and tetramethylethylenediamine copper complex as a catalyst, but the reaction requires methanol as a solvent; patent CN116444349A reports a method using alkylphenol as a raw material and aluminum-based hydrotalcite as a catalyst. The methods for catalytic oxidation using alkylphenol as a raw material and tetramethylguanidine copper complex as a catalyst are described, but the reaction requires ethanol as a solvent; patent CN116178111B reports a method for catalytic oxidation using alkylphenol as a raw material and tetramethylguanidine copper complex as a catalyst, but the reaction requires propylene carbonate as a solvent; patent WO2021058935A1 reports a method for catalytic oxidation using alkylphenol as a raw material and a basic compound as a catalyst, but the reaction requires alkylbenzene as a solvent; patent US20030050515A1 reports a method for catalytic oxidation using alkylphenol as a raw material and tetramethylethylenediamine copper complex as a catalyst, but the reaction requires methanol as a solvent.

[0008] It is evident that current methods for preparing biphenyl from alkylphenols generally require the use of organic solvents in the oxidation reaction, and the formation of explosive mixtures is a common problem in these methods. Developing an aqueous-phase method for preparing biphenyl from alkylphenols is an important way to achieve inherent safety and green production of biphenyl. Summary of the Invention

[0009] The problem this invention aims to solve is that the existing process for preparing biphenyl by oxidative coupling of alkylphenols must rely on organic solvents, which leads to the risk of explosion and serious pollution from traditional production processes.

[0010] To address the aforementioned problems, this invention provides a method for the aqueous synthesis of biphenyl diquinone, comprising the following steps: in the presence of a phase transfer catalytic system composed of boric acid, Tween-80, dodecylphenol polyoxyethylene ether, and copper chloride, using water as a solvent, stirring and continuously introducing an oxidant at a temperature of 60°C-90°C, causing alkylphenol to undergo an oxidative coupling reaction to generate alkylbiphenyl diquinone; the obtained alkylbiphenyl diquinone is then subjected to hydrogenation reduction to obtain biphenyl diquinone.

[0011] Preferably, the alkylphenol is selected from one or more of the following: 2,6-di-tert-butylphenol, 3-methylphenol, 3,5-dimethylphenol, and 2,3,5-trimethylphenol.

[0012] Preferably, when feeding the oxidative coupling reaction, the mass ratio of copper chloride to alkylphenol is 1:1000 to 1:100.

[0013] Preferably, in the phase transfer catalytic system, the mass ratio of boric acid to copper chloride is 20:1 to 2:1, the mass ratio of Tween-80 to copper chloride is 5:1 to 1:1, and the mass ratio of dodecylphenol polyoxyethylene ether to copper chloride is 5:1 to 1:1.

[0014] Preferably, when the oxidative coupling reaction is fed, the mass ratio of water to alkylphenol is 5:1 to 1:1.

[0015] Preferably, the oxidant is oxygen or air at normal pressure.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The oxidative coupling reaction stage uses water as the solvent, which completely avoids the possibility of organic solvents forming explosive mixtures with oxygen, thus solving the major safety hazards of this process route from the source.

[0018] 2. Water is inexpensive, non-toxic, and non-volatile as a solvent, which greatly reduces VOC emissions and subsequent recycling costs associated with traditional organic solvents, thus meeting the requirements of green chemistry.

[0019] 3. The quaternary composite system used in this invention, consisting of boric acid, Tween-80, dodecylphenol polyoxyethylene ether and copper chloride, has multiple functions including catalysis, emulsification, solubilization and phase transfer. It synergistically overcomes the problem of low mass transfer and reaction efficiency of alkylphenols in aqueous phase, and can achieve high yield under mild conditions.

[0020] 4. The reaction conditions are mild (atmospheric pressure, medium temperature), the equipment requirements are low, the operation is simple, and water and air (or oxygen) are used as the main media, which significantly reduces the cost of raw materials. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method of the present invention;

[0022] Figure 2 This is a schematic diagram of the reaction in the conventional synthetic route of biphenyl hydroquinone in the existing technology;

[0023] Figure 3 This is a schematic diagram of the reaction route for synthesizing biphenyl from alkylphenol via oxidative coupling. Detailed Implementation

[0024] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto. Those skilled in the art can make modifications or substitutions to the following embodiments without departing from the spirit and substance of the present invention, and such modifications or substitutions all fall within the scope of protection of the present invention.

[0025] In the embodiments of the present invention, unless otherwise specified, the equipment and methods used are conventional equipment and methods in the art; all raw materials and additives can be purchased from the market or prepared using conventional methods in the art.

[0026] Example 1

[0027] To a 500 mL reaction flask equipped with an oxygen distributor and a multi-layered spiral stirrer, 100.0 g of 2,6-di-tert-butylphenol, 200.0 g of water, 1.0 g of copper chloride, 10.0 g of boric acid, 3.0 g of Tween-80, and 3.0 g of dodecylphenol polyoxyethylene ether were added sequentially. After the addition was complete, oxygen was continuously introduced into the reaction system, and the mixture was heated to 80 °C under vigorous stirring and reacted at this temperature for 10 hours. After the reaction was completed, the mixture was allowed to stand and the organic phase was separated. A sample was analyzed by liquid chromatography, and the yield of 2,2',6,6'-tetra-tert-butyl-4,4'-biphenyldiquinone was calculated to be 87.3%.

[0028] Example 2

[0029] To a 500 mL reaction flask equipped with an oxygen distributor and a multi-layered spiral stirrer, 100.0 g of 3-methylphenol, 200.0 g of water, 1.0 g of copper chloride, 10.0 g of boric acid, 3.0 g of Tween-80, and 3.0 g of dodecylphenol polyoxyethylene ether were added sequentially. After the addition was complete, oxygen was continuously introduced into the reaction system, and the mixture was heated to 80 °C under vigorous stirring and reacted at this temperature for 10 hours. After the reaction was completed, the mixture was allowed to stand and the organic phase was separated. A sample was analyzed by liquid chromatography, and the yield of 3,3'-dimethyl-4,4'-biphenyldiquinone was calculated to be 85.1%.

[0030] Example 3

[0031] To a 500 mL reaction flask equipped with an oxygen distributor and a multi-layered spiral stirrer, 100.0 g of 3,5-dimethylphenol, 200.0 g of water, 1.0 g of copper chloride, 10.0 g of boric acid, 3.0 g of Tween-80, and 3.0 g of dodecylphenol polyoxyethylene ether were added sequentially. After the addition was complete, oxygen was continuously introduced into the reaction system, and the mixture was heated to 80 °C under vigorous stirring and reacted at this temperature for 10 hours. After the reaction was completed, the mixture was allowed to stand and the organic phase was separated. A sample was analyzed by liquid chromatography, and the yield of 3,3',5,5'-tetramethyl-4,4'-biphenyldiquinone was calculated to be 83.1%.

[0032] Example 4

[0033] To a 500 mL reaction flask equipped with an oxygen distributor and a multi-layered spiral stirrer, 100.0 g of 2,3,5-trimethylphenol, 200.0 g of water, 1.0 g of copper chloride, 10.0 g of boric acid, 3.0 g of Tween-80, and 3.0 g of dodecylphenol polyoxyethylene ether were added sequentially. After the addition was complete, oxygen was continuously introduced into the reaction system, and the mixture was heated to 80 °C under vigorous stirring and reacted at this temperature for 10 hours. After the reaction was completed, the mixture was allowed to stand and the organic phase was separated. A sample was analyzed by liquid chromatography, and the yield of 2,2',3,3',5,5'-hexamethyl-4,4'-biphenyldiquinone was calculated to be 81.0%.

[0034] Example 5

[0035] The difference between this embodiment and Example 1 is that the amount of water was increased to 500.0 g, while the other raw materials, amounts, and reaction conditions were the same as in Example 1. After the reaction was completed, the yield was determined, and the yield of 2,2',6,6'-tetratert-butyl-4,4'-biphenyldiquinone was 76.6%.

[0036] Example 6

[0037] The difference between this embodiment and Example 1 is that the amount of water used is reduced to 100.0 g, while the other raw materials, amounts, and reaction conditions are the same as in Example 1. After the reaction is complete, the yield is determined, and the yield of 2,2',6,6'-tetratert-butyl-4,4'-biphenyldiquinone is 89.1%.

[0038] Example 7: The difference between this example and Example 1 is that the amount of copper chloride used is reduced to 0.1 g, while the other raw materials, amounts, and reaction conditions are the same as in Example 1. After the reaction, the yield was determined, and the yield of 2,2',6,6'-tetratert-butyl-4,4'-biphenyldiquinone was 59.4%.

[0039] Example 8

[0040] The difference between this embodiment and Example 1 is that the amount of boric acid was increased to 20.0 g, while the other raw materials, amounts, and reaction conditions were the same as in Example 1. After the reaction was completed, the yield was determined, and the yield of 2,2',6,6'-tetratert-butyl-4,4'-biphenyldiquinone was 88.2%.

[0041] Example 9

[0042] The difference between this embodiment and Example 1 is that the amount of Tween-80 was increased to 5.0 g, while the other raw materials, amounts, and reaction conditions were the same as in Example 1. After the reaction was completed, the yield was determined, and the yield of 2,2',6,6'-tetratert-butyl-4,4'-biphenyldiquinone was 87.9%.

[0043] Example 10

[0044] The difference between this example and Example 1 is that the amount of dodecylphenol polyoxyethylene ether was increased to 5.0 g, while the other raw materials, amounts, and reaction conditions were the same as in Example 1. After the reaction was completed, the yield was determined, and the yield of 2,2',6,6'-tetratert-butyl-4,4'-biphenyldiquinone was 89.0%.

[0045] Example 11

[0046] The difference between this embodiment and Example 1 is that the reaction temperature was adjusted to 60°C, while the other raw materials, amounts, and reaction conditions were the same as in Example 1. After the reaction was completed, the yield was measured, and the yield of 2,2',6,6'-tetratert-butyl-4,4'-biphenyldiquinone was 55.7%.

[0047] Example 12

[0048] The difference between this embodiment and Example 1 is that the reaction temperature was adjusted to 90°C, while the other raw materials, amounts, and reaction conditions were the same as in Example 1. After the reaction was completed, the yield was measured, and the yield of 2,2',6,6'-tetra-tert-butyl-4,4'-biphenyldiquinone was 83.6%.

[0049] Example 13

[0050] The difference between this embodiment and Example 1 is that the oxidant introduced is replaced with air instead of oxygen; all other raw materials, amounts, and reaction conditions are the same as in Example 1. After the reaction, the yield was measured, and the yield of 2,2',6,6'-tetratert-butyl-4,4'-biphenyldiquinone was 63.9%.

[0051] Example 14

[0052] To a 500 mL high-pressure reactor, 50.0 g of the crude 2,2',6,6'-tetra-tert-butyl-4,4'-biphenyldiquinone product obtained in Example 1, 200.0 g of ethyl acetate, and 1.0 g of palladium on carbon catalyst (Pd content 5%) were added sequentially. After the addition was complete, the reactor was purged three times with hydrogen to remove air, and then hydrogen was introduced to a pressure of 3 MPa. The temperature was raised to 100 °C and the reaction was carried out under vigorous stirring for 5 hours. After the reaction was completed, a sample was taken and analyzed by liquid chromatography. The yield of 2,2',6,6'-tetra-tert-butyl-4,4'-biphenyldiquinone was calculated to be 96.7%.

[0053] Example 15

[0054] To a 500 mL high-pressure reactor, 50.0 g of the crude 3,3'-dimethyl-4,4'-biphenyldiquinone product obtained in Example 2, 200.0 g of ethyl acetate, and 1.0 g of palladium on carbon catalyst (Pd content 5%) were added sequentially. After the addition was complete, the reactor was purged three times with hydrogen to remove air, and then hydrogen was introduced to a pressure of 3 MPa. The temperature was raised to 100 °C and the reaction was carried out under vigorous stirring for 5 hours. After the reaction was completed, a sample was taken and analyzed by liquid chromatography. The yield of 3,3'-dimethyl-4,4'-biphenyldiquinone was calculated to be 97.2%.

[0055] Effect Analysis:

[0056] Examples 1-13 above fully verify the feasibility and superiority of the aqueous phase oxidative coupling step of the present invention. Examples 1-4 show that the quaternary phase transfer catalytic system of the present invention is applicable to various alkylphenols with different structures, and can obtain the corresponding biphenyl diquinone in high yield (81.0%-87.3%). Examples 5-7 and 11-13 systematically investigated the effects of water dosage, catalyst dosage, reaction temperature, and oxidant type on the reaction, proving that better results (yield 83.6%-89.1%) can be obtained within the preferred range of the present invention (e.g., water:alkylphenol mass ratio 1:1-5:1, temperature 60-90℃, oxygen as oxidant). Examples 8-10 further show that the components in the catalytic system have good synergistic effects under the preferred ratio. Examples 14-15 demonstrate that the oxidation product can be efficiently converted into the final product biphenyl diquinone after conventional hydrogenation reduction, with an ideal total yield of the two steps.

[0057] In summary, this invention successfully provides a new route for the efficient synthesis of biphenyl hydroquinone using water as a safe medium.

[0058] In light of current practical needs, the above-described embodiments of this invention are not limited to these specific implementations. Any changes made within the scope of knowledge possessed by those skilled in the art, without departing from the concept of this invention, still fall within the protection scope of this invention.

Claims

1. A method for the aqueous phase synthesis of biphenyl hydroquinone, characterized in that, Includes the following steps: In the presence of a phase transfer catalytic system composed of boric acid, Tween-80, dodecylphenol polyoxyethylene ether, and copper chloride, water is used as a solvent, and an oxidant is continuously introduced while stirring at a temperature of 60℃-90℃ to induce an oxidative coupling reaction of alkylphenol to generate alkylbiphenyl diquinone. The obtained alkylbiphenyl diquinone is then hydrogenated to obtain biphenyl hydroquinone.

2. The method for aqueous synthesis of biphenyl hydroquinone according to claim 1, characterized in that, The alkylphenol is selected from one or more of the following: 2,6-di-tert-butylphenol, 3-methylphenol, 3,5-dimethylphenol, and 2,3,5-trimethylphenol.

3. The method for aqueous synthesis of biphenyl hydroquinone according to claim 1, characterized in that, When feeding the oxidative coupling reaction, the mass ratio of copper chloride to alkylphenol is 1:1000 to 1:

100.

4. The method for aqueous synthesis of biphenyl hydroquinone according to claim 1, characterized in that, In the phase transfer catalytic system, the mass ratio of boric acid to copper chloride is 20:1 to 2:1, the mass ratio of Tween-80 to copper chloride is 5:1 to 1:1, and the mass ratio of dodecylphenol polyoxyethylene ether to copper chloride is 5:1 to 1:

1.

5. The method for aqueous synthesis of biphenyl hydroquinone according to claim 1, characterized in that, When feeding the oxidative coupling reaction, the mass ratio of water to alkylphenol is 5:1 to 1:

1.

6. The method for aqueous synthesis of biphenyl hydroquinone according to claim 1, characterized in that, The oxidant is oxygen or air at normal pressure.

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