A process for the preparation of a biphenol

Abstract

The application relates to the technical field of organic synthesis, in particular to a preparation method of biphenol, wherein under visible light irradiation, biphenyl, a catalyst, acetonitrile and hydrogen peroxide are mixed and reacted, then filtered, the obtained filtrate is distilled, and the product is collected, so that the biphenol is prepared; the catalyst is a rare earth doped transition metal organic framework microsphere, the method has mild reaction conditions, is easy to operate, no toxic waste liquid is generated, and a new idea is provided for the preparation of the biphenol.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, specifically to a method for preparing biphenyl hydroquinone. Background Technology

[0002] 4,4'-Biphenyl (DOD) is an important organic intermediate with a wide range of applications in polymer materials, rubber and plastics industries, electronics and communications, and medical fields.

[0003] Currently, the main methods for synthesizing 4,4'-biphenyldiol include the benzidine method, the biphenyl sulfonation alkaline fusion method, the biphenyl halogenation high-pressure hydrolysis method, and the 3,5,3',5'-tetra-tert-butyl-4,4'-biphenyldiol detert-butylation method. The benzidine method has low yield and poor product quality. The biphenyl sulfonation alkaline fusion method and the biphenyl halogenation high-pressure hydrolysis method require high reaction conditions, are highly toxic, and have unsatisfactory yields. The 3,5,3',5'-tetra-tert-butyl-4,4'-biphenyldiol detert-butylation method requires large amounts of aluminum trichloride and phenol, which makes product purification difficult.

[0004] Existing technologies report a technical route for the highly selective catalytic hydroxylation of benzene to prepare phenol under visible light irradiation, but no research has been found on the catalytic oxidation of biphenyl to prepare biphenyl diol. Summary of the Invention

[0005] Objective of the invention: To address the above-mentioned technical problems, this invention proposes a method for preparing biphenyl hydroquinone.

[0006] The technical solution adopted is as follows: A method for preparing biphenyl hydroquinone is as follows: Under visible light irradiation, biphenyl, catalyst, acetonitrile, and hydrogen peroxide are mixed and reacted, then filtered. The resulting filtrate is distilled, and the product is collected. The catalyst is a rare earth-doped transition metal organic framework microsphere.

[0007] Furthermore, the rare earth-doped transition metal-organic framework microspheres are rare earth-doped iron-based metal-organic framework microspheres.

[0008] Furthermore, the preparation method of the rare earth-doped iron-based metal-organic framework microspheres is as follows: Ferrous salt and trimesic acid were dissolved in a polar aprotic solvent. The solution was transferred to a high-pressure reactor and reacted under sealed conditions at 140℃-160℃. After the reaction was completed, the product was separated, washed, and dried to obtain iron-based metal-organic framework microspheres. The iron-based metal-organic framework microspheres and rare earth salt solution were added to a high-pressure reactor and reacted under sealed conditions at 140℃-160℃. After the reaction was completed, the product was separated, washed, and dried.

[0009] Furthermore, the rare earth element is lanthanum, cerium, praseodymium, or neodymium.

[0010] Furthermore, the rare earth-doped iron-based metal-organic framework microspheres are also loaded with phosphomolybdenum-vanadium heteropolyacid ionic liquid.

[0011] Furthermore, the catalyst is prepared as follows: Rare earth-doped iron-based metal-organic framework microspheres were dispersed in deionized water to obtain solution A. Phosphomolybdate-vanadium heteropolyacid was dissolved in deionized water to obtain solution B. An ionic liquid was dissolved in deionized water to obtain solution C. Solutions B and C were added to solution A. After stirring and reacting, the products were separated, washed, and dried.

[0012] Furthermore, the ionic liquid is an imidazole-based ionic liquid.

[0013] Furthermore, the anion of the imidazole ionic liquid is tetrafluoroborate or hexafluorophosphate.

[0014] Furthermore, the amount of catalyst used is 0.1%-1% of the mass of biphenyl.

[0015] Furthermore, the reaction temperature is ≥25℃.

[0016] The beneficial effects of this invention are: This invention provides a method for preparing biphenyl hydroquinone. Biphenyl has a biphenyl ring structure, and its oxidation requires the simultaneous activation of both benzene rings and the para-selective introduction of hydroxyl groups. In contrast, the hydroxylation of a single benzene ring only requires activation of a single site. Moreover, the rigid structure of biphenyl leads to a weakening of the interaction between the active site of the catalyst and the benzene ring, thus reducing the catalytic efficiency. Therefore, the catalytic oxidation of biphenyl to prepare biphenyl hydroquinone is much more difficult than the preparation of phenol by the hydroxylation of a single benzene ring.

[0017] After being doped with rare earth elements, iron-based metal-organic framework microspheres can generate more lattice vacant oxygen on the catalyst surface and expose more sites due to the synergistic effect between rare earth elements and iron. This promotes the adsorption and activation of biphenyl through π-π interactions, thereby improving catalytic performance. It can also stabilize key intermediates in the biphenyl hydroxylation process, thus improving the catalytic selectivity of biphenyl hydroquinone.

[0018] Both phosphomolybdenum-vanadium heteropolyacid and ionic liquids can serve as strong redox centers, catalyzing the homolytic cleavage of H2O2 under illumination to generate highly active hydroxyl radicals. These hydroxyl radicals activate biphenyl, forming a radical intermediate. Rare-earth-doped iron-based metal-organic framework microspheres capture photogenerated electrons to generate photogenerated holes, which then oxidize the radical intermediate to produce biphenyl hydroquinone. The phosphomolybdenum-vanadium heteropolyacid ionic liquid obtained from the reaction of phosphomolybdenum-vanadium heteropolyacid and ionic liquid serves as a supporting phase, significantly improving the yield of biphenyl hydroquinone. Furthermore, it avoids the problem of easy dissolution in the aqueous phase and difficulty in recycling when using only phosphomolybdenum-vanadium heteropolyacid and ionic liquid. The method of this invention features mild reaction conditions, is easy to operate, and produces no toxic waste liquid, providing a new approach for the preparation of biphenyl hydroquinone. Detailed Implementation

[0019] Unless otherwise specified in the examples, the conditions were performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Techniques not mentioned in this invention refer to existing technologies. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters. Example 1

[0020] A method for preparing biphenyl hydroquinone: In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.01 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of hydrogen peroxide (30%) was added dropwise, with the addition time controlled at approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was completed, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain the crude product. The crude product was separated by column chromatography, and the eluent (petroleum ether: ethyl acetate = 8:1) was collected and concentrated under reduced pressure to obtain biphenyl hydroquinone, with a yield of 30.6%. ESI-MS (m / z) (M+): theoretical value 186.21, measured value 186.48, purity 99.6% (HPLC).

[0021] The catalyst is a neodymium-doped iron-based metal-organic framework microsphere supported on a phosphomolybdenum-vanadium heteropolyacid ionic liquid. The preparation method of the catalyst is as follows: 48 mmol of ferrous sulfate and 48 mmol of trimesic acid were dissolved in 250 mL of LDM and stirred thoroughly. The solution was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 12 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain iron-based metal-organic framework microspheres. 1 g of iron-based metal-organic framework microspheres were mixed with 10 mL of 30 mmol / L neodymium nitrate solution. The resulting mixture was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 8 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain neodymium-doped iron-based metal-organic framework microspheres.

[0022] Dissolve 0.01 mol sodium dihydrogen phosphate and 0.1 mol sodium molybdate in 100 mL of deionized water, stir thoroughly, heat to boiling, and react for 30 min. Then add 0.025 mol sodium metavanadate and continue reacting for another 30 min. Stop heating and slowly add a 1:1 diluted sulfuric acid solution (concentrated sulfuric acid to deionized water volume ratio of 1:1) to the solution to adjust the pH to 2-2.5. Add 100 mL of diethyl ether to the reaction solution and shake thoroughly. After the solution separates into layers, continue adding a 1:1 diluted sulfuric acid solution until the intermediate phase turns light yellow. Transfer the lower oily brownish-red liquid, concentrate it appropriately, add deionized water, and crystallize in a cold trap at 0-5℃ for 10 h. Filter the solution and dry the resulting product to obtain phosphomolybdate-vanadium heteropoly acid.

[0023] Solution A was prepared by dispersing 1 g of neodymium-doped iron-based metal-organic framework microspheres in 100 mL of deionized water. Solution B was prepared by dissolving 0.5 g of phosphomolybdic vanadium heteropolyacid in 50 mL of deionized water. Solution C was prepared by dissolving 0.5 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid in 50 mL of deionized water. Solutions B and C were added dropwise to solution A. After the addition was complete, the mixture was stirred and reacted for 24 h. The product was then separated by filtration, washed with deionized water, and dried in an oven at 60 °C for 24 h. Example 2

[0024] A method for preparing biphenyl hydroquinone: In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.05 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of hydrogen peroxide (30%) was added dropwise, with the addition time controlled at approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was completed, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain the crude product. The crude product was separated by column chromatography, and the eluent (petroleum ether: ethyl acetate = 8:1) was collected and concentrated under reduced pressure to obtain biphenyl hydroquinone, with a yield of 32.1%. ESI-MS (m / z) (M+): theoretical value 186.21, measured value 186.33, purity 99.4% (HPLC).

[0025] The catalyst is a neodymium-doped iron-based metal-organic framework microsphere supported on a phosphomolybdenum-vanadium heteropolyacid ionic liquid, and the catalyst is prepared in the same way as in Example 1.

[0026] The difference between this embodiment and Example 1 is that the amount of catalyst used is increased, which shows that the reaction yield is increased to a certain extent. Example 3

[0027] A method for preparing biphenyl hydroquinone: In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.1 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of hydrogen peroxide (30%) was added dropwise, with the addition time controlled at approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was completed, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain the crude product. The crude product was separated by column chromatography, and the eluent (petroleum ether: ethyl acetate = 8:1) was collected and concentrated under reduced pressure to obtain biphenyl hydroquinone, with a yield of 32.3%. ESI-MS (m / z) (M+): theoretical value 186.21, measured value 186.04, purity 99.3% (HPLC).

[0028] The catalyst is a neodymium-doped iron-based metal-organic framework microsphere supported on a phosphomolybdenum-vanadium heteropolyacid ionic liquid, and the catalyst is prepared in the same way as in Example 1.

[0029] The difference between this embodiment and Example 2 is that the amount of catalyst is increased again. At this amount, the reaction yield is basically not increased. Example 4

[0030] A method for preparing biphenyl hydroquinone: In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.01 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of hydrogen peroxide (30%) was added dropwise, with the addition time controlled at approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was completed, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain the crude product. The crude product was separated by column chromatography, and the eluent (petroleum ether: ethyl acetate = 8:1) was collected and concentrated under reduced pressure to obtain biphenyl hydroquinone, with a yield of 24.5%. ESI-MS (m / z) (M+): theoretical value 186.21, measured value 186.50, purity 99.1% (HPLC).

[0031] The catalyst is a lanthanum-doped iron-based metal-organic framework microsphere supported on a phosphomolybdenum-vanadium heteropolyacid ionic liquid. The preparation method of the catalyst is as follows: 48 mmol of ferrous sulfate and 48 mmol of trimesic acid were dissolved in 250 mL of LDM and stirred thoroughly. The solution was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 12 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. The product was then dried in an oven at 60 °C for 24 h to obtain iron-based metal-organic framework microspheres. 1 g of iron-based metal-organic framework microspheres were mixed with 10 mL of 30 mmol / L lanthanum nitrate solution. The resulting mixture was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 8 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. The product was then dried in an oven at 60 °C for 24 h to obtain lanthanum-doped iron-based metal-organic framework microspheres.

[0032] Dissolve 0.01 mol sodium dihydrogen phosphate and 0.1 mol sodium molybdate in 100 mL of deionized water, stir thoroughly, heat to boiling, and react for 30 min. Then add 0.025 mol sodium metavanadate and continue reacting for another 30 min. Stop heating and slowly add a 1:1 diluted sulfuric acid solution (concentrated sulfuric acid to deionized water volume ratio of 1:1) to the solution to adjust the pH to 2-2.5. Add 100 mL of diethyl ether to the reaction solution and shake thoroughly. After the solution separates into layers, continue adding a 1:1 diluted sulfuric acid solution until the intermediate phase turns light yellow. Transfer the lower oily brownish-red liquid, concentrate it appropriately, add deionized water, and crystallize in a cold trap at 0-5℃ for 10 h. Filter the solution and dry the resulting product to obtain phosphomolybdate-vanadium heteropoly acid.

[0033] Solution A was prepared by dispersing 1 g of lanthanum-doped iron-based metal-organic framework microspheres in 100 mL of deionized water. Solution B was prepared by dissolving 0.5 g of phosphomolybdic vanadium heteropolyacid in 50 mL of deionized water. Solution C was prepared by dissolving 0.5 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid in 50 mL of deionized water. Solutions B and C were added dropwise to solution A. After the addition was complete, the mixture was stirred and reacted for 24 h. The product was then separated by filtration, washed with deionized water, and dried in an oven at 60 °C for 24 h.

[0034] The difference between this embodiment and Example 1 is that the rare earth element is replaced by lanthanum instead of neodymium, resulting in a decrease in reaction yield. Example 5

[0035] A method for preparing biphenyl hydroquinone: In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.01 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of hydrogen peroxide (30%) was added dropwise, with the addition time controlled at approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was completed, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain the crude product. The crude product was separated by column chromatography, and the eluent (petroleum ether: ethyl acetate = 8:1) was collected and concentrated under reduced pressure to obtain biphenyl hydroquinone, with a yield of 27.9%. ESI-MS (m / z) (M+): theoretical value 186.21, measured value 186.27, purity 99.4% (HPLC).

[0036] The catalyst is a cerium-doped iron-based metal-organic framework microsphere supported on a phosphomolybdenum-vanadium heteropolyacid ionic liquid. The preparation method of the catalyst is as follows: 48 mmol of ferrous sulfate and 48 mmol of trimesic acid were dissolved in 250 mL of LDM and stirred thoroughly. The solution was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 12 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain iron-based metal-organic framework microspheres. 1 g of iron-based metal-organic framework microspheres were mixed with 10 mL of 30 mmol / L cerium nitrate solution. The resulting mixture was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 8 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain cerium-doped iron-based metal-organic framework microspheres.

[0037] Dissolve 0.01 mol sodium dihydrogen phosphate and 0.1 mol sodium molybdate in 100 mL of deionized water, stir thoroughly, heat to boiling, and react for 30 min. Then add 0.025 mol sodium metavanadate and continue reacting for another 30 min. Stop heating and slowly add a 1:1 diluted sulfuric acid solution (concentrated sulfuric acid to deionized water volume ratio of 1:1) to the solution to adjust the pH to 2-2.5. Add 100 mL of diethyl ether to the reaction solution and shake thoroughly. After the solution separates into layers, continue adding a 1:1 diluted sulfuric acid solution until the intermediate phase turns light yellow. Transfer the lower oily brownish-red liquid, concentrate it appropriately, add deionized water, and crystallize in a cold trap at 0-5℃ for 10 h. Filter the solution and dry the resulting product to obtain phosphomolybdate-vanadium heteropoly acid.

[0038] Solution A was prepared by dispersing 1 g of cerium-doped iron-based metal-organic framework microspheres in 100 mL of deionized water. Solution B was prepared by dissolving 0.5 g of phosphomolybdic vanadium heteropolyacid in 50 mL of deionized water. Solution C was prepared by dissolving 0.5 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid in 50 mL of deionized water. Solutions B and C were added dropwise to solution A. After the addition was complete, the mixture was stirred and reacted for 24 h. The product was then separated by filtration, washed with deionized water, and dried in an oven at 60 °C for 24 h.

[0039] The difference between this embodiment and Embodiment 1 is that the rare earth element is replaced by cerium instead of neodymium, resulting in a decrease in reaction yield. Example 6

[0040] A method for preparing biphenyl hydroquinone: In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.01 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of hydrogen peroxide (30%) was added dropwise, with the addition time controlled at approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was completed, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain the crude product. The crude product was separated by column chromatography, and the eluent (petroleum ether: ethyl acetate = 8:1) was collected and concentrated under reduced pressure to obtain biphenyl hydroquinone, with a yield of 28.3%. ESI-MS (m / z) (M+): theoretical value 186.21, measured value 186.17, purity 99.2% (HPLC).

[0041] The catalyst is a praseodymium-doped iron-based metal-organic framework microsphere supported on a phosphomolybdenum-vanadium heteropolyacid ionic liquid. The preparation method of the catalyst is as follows: 48 mmol of ferrous sulfate and 48 mmol of trimesic acid were dissolved in 250 mL of DMF and stirred thoroughly. The solution was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 12 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain iron-based metal-organic framework microspheres. 1 g of iron-based metal-organic framework microspheres were mixed with 10 mL of 30 mmol / L praseodymium nitrate solution. The resulting mixture was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 8 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain praseodymium-doped iron-based metal-organic framework microspheres.

[0042] Dissolve 0.01 mol sodium dihydrogen phosphate and 0.1 mol sodium molybdate in 100 mL of deionized water, stir thoroughly, heat to boiling, and react for 30 min. Then add 0.025 mol sodium metavanadate and continue reacting for another 30 min. Stop heating and slowly add a 1:1 diluted sulfuric acid solution (concentrated sulfuric acid to deionized water volume ratio of 1:1) to the solution to adjust the pH to 2-2.5. Add 100 mL of diethyl ether to the reaction solution and shake thoroughly. After the solution separates into layers, continue adding a 1:1 diluted sulfuric acid solution until the intermediate phase turns light yellow. Transfer the lower oily brownish-red liquid, concentrate it appropriately, add deionized water, and crystallize in a cold trap at 0-5℃ for 10 h. Filter the solution and dry the resulting product to obtain phosphomolybdate-vanadium heteropoly acid.

[0043] Solution A was prepared by dispersing 1 g of praseodymium-doped iron-based metal-organic framework microspheres in 100 mL of deionized water. Solution B was prepared by dissolving 0.5 g of phosphomolybdic acid in 50 mL of deionized water. Solution C was prepared by dissolving 0.5 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid in 50 mL of deionized water. Solutions B and C were added dropwise to solution A. After the addition was complete, the mixture was stirred and reacted for 24 h. The product was then separated by filtration, washed with deionized water, and dried in an oven at 60 °C for 24 h.

[0044] The difference between this embodiment and Embodiment 1 is that the rare earth element is replaced by praseodymium instead of neodymium, resulting in a decrease in reaction yield. Example 7

[0045] A method for preparing biphenyl hydroquinone: In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.01 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of hydrogen peroxide (30%) was added dropwise, with the addition time controlled at approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was completed, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain the crude product. The crude product was separated by column chromatography, and the eluent (petroleum ether: ethyl acetate = 8:1) was collected and concentrated under reduced pressure to obtain biphenyl hydroquinone, with a yield of 2.3%. ESI-MS (m / z) (M+): theoretical value 186.21, measured value 186.73, purity 99.1% (HPLC).

[0046] The catalyst is a neodymium-doped iron-based metal-organic framework microsphere, and the preparation method of the catalyst is as follows: 48 mmol of ferrous sulfate and 48 mmol of trimesic acid were dissolved in 250 mL of LDM and stirred thoroughly. The solution was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 12 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain iron-based metal-organic framework microspheres. 1 g of iron-based metal-organic framework microspheres were mixed with 10 mL of 30 mmol / L neodymium nitrate solution. The resulting mixture was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 8 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain neodymium-doped iron-based metal-organic framework microspheres.

[0047] The difference between this embodiment and Example 1 is that the catalyst is not supported on a phosphomolybdenum-vanadium heteropolyacid ionic liquid, resulting in a significant decrease in reaction yield. Comparative Example 1

[0048] It is basically the same as Example 1, except that the catalyst is an iron-based metal-organic framework microsphere.

[0049] In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.01 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of 30% hydrogen peroxide was added dropwise over approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was complete, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain the crude product. The crude product was sent for analysis, and no biphenyl ion peak was detected by mass spectrometry. This indicates that iron-based metal-organic framework microspheres cannot catalyze the oxidation of biphenyl to biphenyl.

[0050] The catalyst is prepared as follows: 48 mmol of ferrous sulfate and 48 mmol of trimesic acid were dissolved in 250 mL of LDM and stirred thoroughly. The solution was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 12 h. After the reaction was completed, the product was centrifuged, washed three times each with deionized water and ethanol, and then dried in an oven at 60 °C for 24 h to obtain iron-based metal-organic framework microspheres. Comparative Example 2

[0051] It is basically the same as Example 1, except that the catalyst is a phosphomolybdenum-vanadium heteropoly acid ionic liquid.

[0052] In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.01 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of 30% hydrogen peroxide was added dropwise over approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was complete, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain the crude product. The crude product was sent for analysis, and no biphenyl ion peak was detected by mass spectrometry. This indicates that the phosphomolybdenum-vanadium heteropolyacid ionic liquid cannot catalyze the oxidation of biphenyl to biphenyl.

[0053] The catalyst is prepared as follows: Dissolve 0.01 mol sodium dihydrogen phosphate and 0.1 mol sodium molybdate in 100 mL of deionized water, stir thoroughly, heat to boiling, and react for 30 min. Then add 0.025 mol sodium metavanadate and continue reacting for another 30 min. Stop heating and slowly add a 1:1 diluted sulfuric acid solution (concentrated sulfuric acid to deionized water volume ratio of 1:1) to the solution to adjust the pH to 2-2.5. Add 100 mL of diethyl ether to the reaction solution and shake thoroughly. After the solution separates into layers, continue adding a 1:1 diluted sulfuric acid solution until the intermediate phase turns light yellow. Transfer the lower oily brownish-red liquid, concentrate it appropriately, add deionized water, and crystallize in a cold trap at 0-5℃ for 10 h. Filter the solution and dry the resulting product to obtain phosphomolybdate-vanadium heteropoly acid.

[0054] Dissolve 0.5g of phosphomolybdicavanadium heteropolyacid in 50mL of deionized water to obtain solution A. Dissolve 0.5g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid in 50mL of deionized water to obtain solution B. Add solution A dropwise to solution B. After the addition is complete, stir the reaction for 24h, filter to separate the product, wash with deionized water, and dry in an oven at 60℃ for 24h. Comparative Example 3

[0055] The process is basically the same as in Example 1, except that the catalyst is neodymium-doped iron-based metal-organic framework microspheres supported on phosphomolybdenum-vanadium heteropolyacid.

[0056] In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.01 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of 30% hydrogen peroxide was added dropwise over approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was complete, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain a crude product. The crude product was separated by column chromatography, and the eluent (petroleum ether: ethyl acetate = 8:1) was collected and concentrated under reduced pressure to obtain biphenyl hydrochloride (BPH). The yield was 9.6%. ESI-MS (m / z) (M+): theoretical value 186.21, measured value 186.44, purity 99.3% (HPLC). This indicates that the introduction of phosphomolybdic acid can increase the reaction yield.

[0057] The catalyst is prepared as follows: 48 mmol of ferrous sulfate and 48 mmol of trimesic acid were dissolved in 250 mL of LDM and stirred thoroughly. The solution was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 12 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain iron-based metal-organic framework microspheres. 1 g of iron-based metal-organic framework microspheres were mixed with 10 mL of 30 mmol / L neodymium nitrate solution. The resulting mixture was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 8 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain neodymium-doped iron-based metal-organic framework microspheres.

[0058] Dissolve 0.01 mol sodium dihydrogen phosphate and 0.1 mol sodium molybdate in 100 mL of deionized water, stir thoroughly, heat to boiling, and react for 30 min. Then add 0.025 mol sodium metavanadate and continue reacting for another 30 min. Stop heating and slowly add a 1:1 diluted sulfuric acid solution (concentrated sulfuric acid to deionized water volume ratio of 1:1) to the solution to adjust the pH to 2-2.5. Add 100 mL of diethyl ether to the reaction solution and shake thoroughly. After the solution separates into layers, continue adding a 1:1 diluted sulfuric acid solution until the intermediate phase turns light yellow. Transfer the lower oily brownish-red liquid, concentrate it appropriately, add deionized water, and crystallize in a cold trap at 0-5℃ for 10 h. Filter the solution and dry the resulting product to obtain phosphomolybdate-vanadium heteropoly acid.

[0059] Dissolve 0.5g of phosphomolybdenum vanadium heteropolyacid in 50mL of deionized water to obtain solution A. Add 1g of neodymium-doped iron-based metal-organic framework microspheres to solution A and soak at room temperature for 24h. Filter to separate the product, wash with deionized water and dry in an oven at 60℃ for 24h. Comparative Example 4

[0060] The process is basically the same as in Example 1, except that the catalyst is a neodymium-doped iron-based metal-organic framework microsphere loaded with an ionic liquid.

[0061] In a 500 mL round-bottom three-necked flask equipped with a reflux condenser, thermometer, and magnetic stirrer, 10 g of biphenyl, 0.01 g of catalyst, and 250 mL of acetonitrile were added sequentially. The mixture was heated to 60 °C and stirred for 30 min. Then, 35 mL of 30% hydrogen peroxide was added dropwise, with the addition time controlled at approximately 30 min. After the addition was complete, the mixture was kept at this temperature under visible light for 12 h. After the reaction was completed, the mixture was allowed to return to room temperature, filtered, and the filtrate was distilled under reduced pressure. The product was collected, washed with acetonitrile, and dried to obtain the crude product. The crude product was separated by column chromatography, and the eluent (petroleum ether: ethyl acetate = 8:1) was collected and concentrated under reduced pressure to obtain biphenyl hydroquinone, with a yield of 7.8%. ESI-MS (m / z) (M+): theoretical value 186.21, measured value 186.59, purity 99.5% (HPLC). This indicates that the introduction of ionic liquids can increase the reaction yield.

[0062] The catalyst is prepared as follows: 48 mmol of ferrous sulfate and 48 mmol of trimesic acid were dissolved in 250 mL of LDM and stirred thoroughly. The solution was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 12 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain iron-based metal-organic framework microspheres. 1 g of iron-based metal-organic framework microspheres were mixed with 10 mL of 30 mmol / L neodymium nitrate solution. The resulting mixture was then transferred to a high-pressure reactor, which was sealed and heated to 150 °C for 8 h. After the reaction was complete, the product was centrifuged and washed three times each with deionized water and ethanol. It was then dried in an oven at 60 °C for 24 h to obtain neodymium-doped iron-based metal-organic framework microspheres.

[0063] Dissolve 0.5 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid in 50 mL of deionized water to obtain solution A. Add 1 g of neodymium-doped iron-based metal-organic framework microspheres to solution A and immerse at room temperature for 24 h. After filtration, separate the product, wash with deionized water, and dry in an oven at 60 °C for 24 h.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing biphenyl hydroquinone, characterized in that, Specifically as follows: Under visible light irradiation, biphenyl, catalyst, acetonitrile, and hydrogen peroxide are mixed and reacted, then filtered. The resulting filtrate is distilled, and the product is collected. The catalyst is a rare earth-doped transition metal organic framework microsphere.

2. The method for preparing biphenyl hydroquinone according to claim 1, characterized in that, The rare earth-doped transition metal-organic framework microspheres are rare earth-doped iron-based metal-organic framework microspheres.

3. The method for preparing biphenyl hydroquinone according to claim 2, characterized in that, The preparation method of the rare earth-doped iron-based metal-organic framework microspheres is as follows: Ferrous salt and trimesic acid were dissolved in a polar aprotic solvent. The solution was transferred to a high-pressure reactor and reacted under sealed conditions at 140℃-160℃. After the reaction was completed, the product was separated, washed, and dried to obtain iron-based metal-organic framework microspheres. The iron-based metal-organic framework microspheres and rare earth salt solution were added to a high-pressure reactor and reacted under sealed conditions at 140℃-160℃. After the reaction was completed, the product was separated, washed, and dried.

4. The method for preparing biphenyl hydroquinone according to claim 3, characterized in that, The rare earth element is lanthanum, cerium, praseodymium, or neodymium.

5. The method for preparing biphenyl hydroquinone according to claim 2, characterized in that, The rare earth-doped iron-based metal-organic framework microspheres are also loaded with phosphomolybdenum-vanadium heteropolyacid ionic liquid.

6. The method for preparing biphenyl hydroquinone according to claim 5, characterized in that, The catalyst is prepared as follows: Rare earth-doped iron-based metal-organic framework microspheres were dispersed in deionized water to obtain solution A. Phosphomolybdate-vanadium heteropolyacid was dissolved in deionized water to obtain solution B. An ionic liquid was dissolved in deionized water to obtain solution C. Solutions B and C were added to solution A. After stirring and reacting, the products were separated, washed, and dried.

7. The method for preparing biphenyl hydroquinone according to claim 6, characterized in that, The ionic liquid is an imidazole-based ionic liquid.

8. The method for preparing biphenyl hydroquinone according to claim 7, characterized in that, The anion of the imidazole ionic liquid is tetrafluoroborate or hexafluorophosphate.

9. The method for preparing biphenyl hydroquinone according to claim 1, characterized in that, The amount of catalyst used is 0.1%-1% of the mass of biphenyl.

10. The method for preparing biphenyl hydroquinone according to claim 1, characterized in that, The reaction temperature is ≥25℃.