A method for preparing biphenyl aromatic conjugated polycarboxylic acid

Abstract

The invention discloses a preparation method of a biphenyl aromatic conjugated polycarboxylic acid, which comprises the following steps: (1) reacting an aryl diboronic acid and a halogenated phenyl carboxylic acid ester in the presence of a catalyst, an inorganic base, and an aprotic polar solvent under inert gas protection, adding water and filtering to obtain a solid after the reaction, adding dichloromethane to dissolve the solid, filtering, and rotary evaporating the filtrate to remove the dichloromethane to obtain a biphenyl aromatic conjugated polycarboxylic acid ester; (2) stirring the biphenyl aromatic conjugated polycarboxylic acid ester prepared in step (1) with a strong base in a mixed solvent for reaction, filtering after the reaction, adding acid to the filtrate to adjust the pH value to 1-2, precipitating a solid, and obtaining the biphenyl aromatic conjugated polycarboxylic acid. The above preparation method is simple, time-consuming, and can be purified by the solubility difference between the reactants and the products to obtain a biphenyl aromatic conjugated polycarboxylic acid with a purity of up to 99%, and the yield can reach 60%. It can be used for industrial batch preparation of high-purity biphenyl aromatic conjugated polycarboxylic acids.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, specifically to a method for preparing biphenyl-based aromatic conjugated polycarboxylic acids. Background Technology

[0002] In organic chemistry reactions, the formation of C-C bonds is a powerful and practical synthetic method. The resulting coupling products are widely used in academic research and industrial production, thus attracting widespread attention in the field of organic transformation. Common metal-organic frameworks (MOFs) are composed of ligands and metals, possessing high specific surface area, thermal stability, and porosity. They also have some unsaturated coordination metal sites and special functional groups, making them excellent catalysts.

[0003] Terphenyl polycarboxylic acids are aromatic conjugated carboxylic acid ligands. These compounds contain abundant carboxyl groups and can coordinate with various transition metals, thereby constructing novel and functionally diverse MOF materials. Among them, 3,3',5,5'-terphenyltetracarboxylic acid (H4TPTC) and its analogues are mainly prepared by the bis-Suzuki coupling reaction of p-dibromobenzene and diphenylboronic acid ester (J.Am.Chem.Soc.2012,134,20110–20116), followed by hydrolysis and acidification. However, the yield of this reaction is only 28%, and the product requires purification by column chromatography, making large-scale preparation cumbersome. The pinacol ester borate used in this reaction is expensive and is usually prepared from dimethyl 5-iodophthalate via the Miyaura-Ishiyama-Hartwig boryllation reaction (J.Org.Chem.1995,60,7508–7510), requiring an expensive Ir catalyst.

[0004] Therefore, the current methods for preparing biphenyl-based aromatic conjugated polycarboxylic acids suffer from problems such as low yield and high cost, which seriously limit the actual production and application of biphenyl-based aromatic conjugated polycarboxylic acids. There is an urgent need for a method to obtain high-purity biphenyl-based aromatic conjugated polycarboxylic acids by improving yield and reducing cost. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing biphenyl-based aromatic conjugated polycarboxylic acids, using aryl diboronic acid and halophenyl carboxylic acid esters as reactants, and dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF) as an aprotic polar solvent as a medium, in the presence of a fluorine-containing inorganic base and a palladium catalyst, to efficiently prepare biphenyl-based aromatic conjugated polycarboxylic acids through a double Suzuki coupling reaction.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing biphenyl-based aromatic conjugated polycarboxylic acids, comprising the following steps:

[0008] (1) Aryl diboronic acid and halophenyl carboxylic acid esters are reacted under inert gas protection in the presence of a catalyst, a fluorine-containing inorganic base and an aprotic polar solvent. After the reaction is completed, water is added and the mixture is filtered to obtain a solid. An organic solvent is added to dissolve the solid, and the mixture is filtered. The organic solvent is removed by rotary evaporation to obtain a biphenyl-based aromatic conjugated polycarboxylic acid ester. The aprotic polar solvent is dimethyl sulfoxide and / or N,N-dimethylformamide.

[0009] (2) The biphenyl-based aromatic conjugated polycarboxylic acid ester prepared in step (1) is stirred and reacted with a strong base in a mixed solvent. After the reaction is completed, the mixture is filtered, and acid is added to the filtrate to adjust the pH value to 1-2. The solid is precipitated to obtain the biphenyl-based aromatic conjugated polycarboxylic acid.

[0010] Further, in step (1), the molar ratio of the aryl diboronic acid to the halophenyl carboxylic acid ester is 1:1 to 5, for example, 1:3.

[0011] Further, in step (1), the aryl diboronic acid is terephthalic acid or pinacol terephthalic acid.

[0012] Further, in step (1), the halophenyl carboxylic acid ester is dimethyl 5-bromoisophthalate, diethyl 5-bromoisophthalate, methyl p-bromobenzoate, ethyl p-bromobenzoate, dimethyl 5-iodoisophthalate, diethyl 5-iodoisophthalate, methyl p-iodobenzoate, or ethyl p-iodobenzoate.

[0013] Further, in step (1), the molar ratio of the aryl diboronic acid to the catalyst and the fluorine-containing inorganic base is 1:0.02-0.03:1-4, more preferably 1:0.003:4.

[0014] Further, in step (1), the catalyst is Pd(PPh3)4, PdCl2, Pd(OA)2, Pd(NO3)2 or Pd(PPh3)2Cl2.

[0015] Furthermore, in step (1), the fluorine-containing inorganic base is C. S F, NaF, or KF.

[0016] Furthermore, the fluorine-containing inorganic base is more preferably C S F.

[0017] This invention changes the traditional method by using 1,4-dioxane as a single aprotic solvent and introduces aprotic polar solvents such as DMSO and DMF as the medium, and uses a fluorine-containing inorganic base as the base source. Aprotic polar solvents such as DMSO and DMF can dissolve the cations (e.g., C46) in the base source.S + The envelope at the center stabilizes the cation, then the corresponding anion F - Boron ions are exposed ions, while fluoride ions have a strong nucleophilicity for boron. After forming arylborate anions with boric acid, they can promote the reaction between the borate intermediate and the palladium center. Therefore, in the presence of the specific solvent and base source mentioned above, biphenyl-based aromatic conjugated polycarboxylic acids can be directly prepared by reacting aryl diboronic acid and halophenyl carboxylic acid esters in the presence of a palladium catalyst, without the need for expensive iridium catalysts, and the yield is significantly improved.

[0018] Furthermore, in step (1), the reaction temperature is 80–120°C and the reaction time is 12–24 h.

[0019] Further, in step (1), the organic solvent is dichloromethane.

[0020] Furthermore, in step (2), the molar ratio of the terphenyl polycarboxylic acid ester to the strong base is 1:4 to 10.

[0021] Furthermore, in step (2), the strong base is LiOH, NaOH, or KOH.

[0022] Further, in step (2), the mixed solvent is obtained by mixing tetrahydrofuran and water at a volume ratio of 1:0.5 to 2.

[0023] Furthermore, in step (2), the temperature of the stirring reaction is 60-80°C and the reaction time is 6-12 hours.

[0024] Further, in step (2), the acid is hydrochloric acid, and the concentration of the hydrochloric acid is 20% to 38%.

[0025] Furthermore, the preparation method also includes a purification step, specifically: collecting the solid precipitated in step (2), drying it, adding ethyl acetate to the solid, heating and stirring, and filtering to obtain the biphenyl-based aromatic conjugated polycarboxylic acid.

[0026] Furthermore, the heating and stirring temperature is 60–80°C, and the time is 6–12 hours.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] This invention provides a method for preparing biphenyl-based aromatic conjugated polycarboxylic acids. Using aryl diboronic acid and halophenyl carboxylic acid esters as reactants, and DMSO or DMF as an aprotic polar solvent as a medium, biphenyl-based aromatic conjugated polycarboxylic acids are efficiently prepared via a double Suzuki coupling reaction in the presence of a fluorine-containing inorganic base and a palladium catalyst. The reaction raw materials used in this method are low-cost and readily available, and the method eliminates the need for expensive iridium catalysts, significantly reducing the synthesis cost of biphenyl-based aromatic conjugated polycarboxylic acids. Furthermore, the synthesis method provided by this invention is time-efficient, the reaction product is easily purified to a purity of up to 99%, and the product yield can reach 60%, making it suitable for the mass production of high-purity biphenyl-based aromatic conjugated polycarboxylic acids. Attached Figure Description

[0029] Figure 1 The 3,3',5,5'-terphenyltetracarboxylic acid prepared in Example 1 1 1H NMR (500MHz, DMSO-d6) spectrum;

[0030] Figure 2 The 3,3',5,5'-terphenyltetracarboxylic acid prepared in Example 1 13 C10 NMR (125MHz, DMSO-d6) spectrum. Detailed Implementation

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0033] Example 1

[0034] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0035] (1) Weigh 41.44 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 100 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-terphenyltetracarboxylate.

[0036] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 80°C for 12 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120°C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60°C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 60%.

[0037] The 3,3',5,5'-terphenyltetracarboxylic acid prepared in this embodiment was analyzed by 1H NMR and 1C NMR. The 1H NMR and 1C NMR spectra of the product are shown below. Figure 1 , Figure 2 As shown, the combined analysis of carbon and hydrogen spectra indicates that there are no residues of the raw material or intermediate product 3,3',5,5'-terphenyltetracarboxylic acid tetramethyl ester in the product. The purity of the product prepared in this example is as high as 99% or more.

[0038] Example 2

[0039] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0040] (1) Weigh 41.44 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 38.0 mg of cesium fluoride (0.25 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 80 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-terphenyltetracarboxylate.

[0041] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60 °C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified dropwise with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120 °C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60 °C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 31%.

[0042] Example 3

[0043] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0044] (1) Weigh 62.9 mg of terephthalic acid (0.38 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 100 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-terphenyltetracarboxylate.

[0045] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60 °C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120 °C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60 °C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 58%.

[0046] Example 4

[0047] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0048] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 100 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-triphenyltetracarboxylate.

[0049] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water were mixed evenly in a flask at a molar ratio of 1:10 and stirred at 60°C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified dropwise with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120°C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60°C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 58%.

[0050] Example 5

[0051] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0052] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 80 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-terphenyltetracarboxylate.

[0053] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60 °C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified dropwise with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120 °C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60 °C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 44%.

[0054] Example 6

[0055] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0056] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 120 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-triphenyltetracarboxylate.

[0057] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60 °C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120 °C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60 °C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 54%.

[0058] Example 7

[0059] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0060] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 100 °C for 24 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-triphenyltetracarboxylate.

[0061] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60°C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120°C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60°C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 60%.

[0062] Example 8

[0063] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0064] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 100 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-triphenyltetracarboxylate.

[0065] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60 °C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120 °C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60 °C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 48%.

[0066] Example 9

[0067] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMF as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0068] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMF as solvent, remove the air in the reaction system with N2, and react at 100 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-triphenyltetracarboxylate.

[0069] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60°C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120°C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60°C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 40%.

[0070] Comparative Example 1

[0071] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, sodium carbonate as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0072] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 106.0 mg of sodium carbonate (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 80 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-triphenyltetracarboxylate.

[0073] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60°C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120°C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60°C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 10%.

[0074] Comparative Example 2

[0075] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, potassium carbonate as an inorganic base, tetraphenylphosphine palladium as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0076] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 138.2 mg of potassium carbonate (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 80 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-triphenyltetracarboxylate.

[0077] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60 °C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified dropwise with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120 °C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60 °C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 16%.

[0078] Comparative Example 3

[0079] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium carbonate as an inorganic base, phenylphosphine palladium dichloroisocyanurate as a catalyst, and DMSO as an aprotic polar solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0080] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 325.8 mg of cesium carbonate (1 mmol) and 5.3 mg of phenylphosphine palladium dichlorodicarboxylate (0.0075 mol), mix them evenly in a reaction tube, add DMSO as solvent, remove the air in the reaction system with N2, and react at 80 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-terphenyltetracarboxylate.

[0081] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60 °C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120 °C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60 °C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 24%.

[0082] Comparative Example 4

[0083] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and ethylene carbonate as a solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0084] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add ethylene carbonate as a solvent, remove the air in the reaction system with N2, and react at 100 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-triphenyltetracarboxylate.

[0085] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60°C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120°C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60°C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 20%.

[0086] Comparative Example 5

[0087] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and dioxane as a solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0088] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add dioxane as a solvent, remove the air in the reaction system with N2, and react at 100 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-triphenyltetracarboxylate.

[0089] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60°C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120°C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60°C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 11%.

[0090] Comparative Example 6

[0091] This embodiment relates to the preparation of terphenyltetracarboxylic acid, using terephthalobolic acid and dimethyl 5-bromoisophthalate as reactants, cesium fluoride as an inorganic base, tetraphenylphosphine palladium as a catalyst, and 1,4-dioxane as a solvent. The terphenyltetracarboxylic acid is obtained through a double-suzuki reaction followed by hydrolysis and acidification. The specific preparation process is as follows:

[0092] (1) Weigh 41.4 mg of terephthalic acid (0.25 mmol), 204.8 mg of dimethyl 5-bromoisophthalate (0.75 mmol), 151.9 mg of cesium fluoride (1 mmol) and 8.7 mg of tetraphenylphosphine palladium (0.0075 mol), mix them evenly in a reaction tube, add 1,4-dioxane as solvent, remove the air in the reaction system with N2, and react at 100 °C for 12 hours. After the reaction is completed, add a large amount of water to the reaction solution and filter it to obtain a grayish-white solid. Dissolve the grayish-white solid with dichloromethane and filter it. Remove the dichloromethane from the filtrate by rotary evaporation to obtain tetramethyl 3,3',5,5'-triphenyltetracarboxylate.

[0093] (2) Tetramethyl 3,3',5,5'-terphenyltetracarboxylate and lithium hydroxide, 4 mL tetrahydrofuran and 4 mL water in a molar ratio of 1:4 were uniformly mixed and added to a flask. The mixture was stirred at 60 °C for 6 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble matter. The filtrate was acidified with concentrated hydrochloric acid to a pH of 1-2 to obtain a white precipitate. The precipitate was filtered to obtain a white solid, which was dried at 120 °C to obtain the terphenyltetracarboxylic acid product. The crude terphenyltetracarboxylic acid product was dissolved in a certain amount of ethyl acetate and stirred overnight at 60 °C. The product 3,3',5,5'-terphenyltetracarboxylic acid was obtained by filtration with a yield of 21%.

[0094] As can be seen from the above examples and comparative examples, the present invention uses terephthaloic acid and dimethyl 5-bromoisophthalate as reactants, and in the presence of an inorganic base, a palladium catalyst, and a solvent, can react to obtain tetramethyl 3,3',5,5'-terphenyltetracarboxylate, which is then hydrolyzed and acidified to obtain terphenyltetracarboxylic acid. When the solvent is DMSO or DMF and the inorganic base is cesium fluoride, the product yield can be increased to 60% under suitable reaction conditions; if the type of solvent or inorganic base is changed, the product yield decreases significantly.

[0095] The embodiments described above are merely preferred examples to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A method for preparing a biphenyl-based aromatic conjugated polycarboxylic acid, characterized in that, The following steps are involved: (1) Under inert gas protection, aryl diboronic acid and halophenyl carboxylic acid esters are reacted in the presence of a catalyst, a fluorinated inorganic base and an aprotic polar solvent. After the reaction is completed, water is added and the mixture is filtered to obtain a solid. An organic solvent is added to dissolve the solid, and the mixture is filtered. The organic solvent is removed by rotary evaporation of the filtrate to obtain a biphenyl-based aromatic conjugated polycarboxylic acid ester. The aprotic polar solvent is dimethyl sulfoxide and / or N,N-dimethylformamide. The aryl diboronic acid is terephthalic acid. The catalyst is Pd(PPh3)4. The fluorinated inorganic base is CsF. The halophenyl carboxylic acid ester is dimethyl 5-bromoisophthalate. The molar ratio of aryl diboronic acid to catalyst and fluorinated inorganic base is 1:0.03:

4. (2) The biphenyl aromatic conjugated polycarboxylic acid ester prepared in step (1) is stirred and reacted with a strong base in a mixed solvent. After the reaction is completed, the mixture is filtered, and acid is added to the filtrate to adjust the pH value to 1~2. The solid is precipitated to obtain the biphenyl aromatic conjugated polycarboxylic acid ester. The molar ratio of the biphenyl aromatic conjugated polycarboxylic acid ester to the strong base is 1:4~10.

2. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of aryl diboronic acid to halophenyl carboxylic acid ester is 1:1~5.

3. The preparation method according to claim 1, characterized in that, In step (1), the reaction temperature is 80~120℃ and the reaction time is 12~24 h; the organic solvent is dichloromethane.

4. The preparation method according to claim 1, characterized in that, In step (2), the strong base is LiOH, NaOH or KOH.

5. The preparation method according to claim 1, characterized in that, In step (2), the mixed solvent is obtained by mixing tetrahydrofuran and water at a volume ratio of 1:0.5~2.

6. The preparation method according to claim 1, characterized in that, In step (2), the temperature of the stirring reaction is 60~80 ℃ and the reaction time is 6~12 h.

7. The preparation method according to claim 1, characterized in that, In step (2), the acid is hydrochloric acid, and the concentration of the hydrochloric acid is 20%~38%.

8. The preparation method according to claim 1, characterized in that, The preparation method also includes a purification step, specifically: collecting the solid precipitated in step (2), drying it, adding ethyl acetate to the solid, heating and stirring, and filtering to obtain the biphenyl-based aromatic conjugated polycarboxylic acid.

9. The preparation method according to claim 8, characterized in that, The heating and stirring temperature is 60~80 ℃, and the time is 6~12 h.

Images