A method for synthesizing 1,4-di(4-fluorobenzoyl)benzene

Abstract

The invention provides a novel method for synthesizing 1,4-di(4-fluorobenzoyl)benzene, which belongs to the technical field of aromatic halogenated product production. The method comprises the following steps: adding a supported solid acid and fluorobenzene into a reaction container under an inert gas; dropping terephthaloyl chloride into the reaction container, and reacting at 5-30 DEG C for 1-8 hours to obtain 1,4-di(4-fluorobenzoyl)benzene; purifying the reaction system to obtain 1,4-di(4-fluorobenzoyl)benzene with a purity of more than 97.2%; the supported solid acid consists of a carrier and a Lewis acid; the Lewis acid is selected from any one of aluminum chloride, ferric chloride, titanium tetrachloride and zinc chloride; and the carrier is selected from any one of HY molecular sieve, Hβ molecular sieve, ZSM-5 molecular sieve, acid-treated K10 montmorillonite, aluminum oxide and MCM-41 molecular sieve. The reaction system of the present invention has mild conditions, and the product purity is ≥97.2%. After optimizing the conditions, the purity is greater than 99.5%. The product and the catalyst can be separated by filtration, thus avoiding the generation of waste salts. The catalyst can be recycled, and the reaction is green and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of aromatic halogenated compound production, and in particular to a new method for synthesizing 1,4-di(4-fluorobenzoyl)benzene. Background Art

[0002] Polyaryletherketone (PEAK) is a type of semi-crystalline thermoplastic polymer with high stability and high mechanical strength. It is widely used in high-tech fields such as aviation, aerospace, and microelectronics. Its typical products include polyaryletheretherketone (PEEK) developed by ICI and polyaryletherketoneketone (PEKK) developed by DuPont. 1,4-Di(4-fluorobenzoyl)benzene is a monomer that can be used to synthesize PEKK and PEEK, as shown in the following formula, but there is currently no green, environmentally friendly, and efficient synthesis method.

[0003]

[0004] The melting point of 1,4-di(4-fluorobenzoyl)benzene is 220-222°C. One way to prepare this substance is to perform electrophilic substitution between aromatic acyl chloride and aromatic halide in the presence of Lewis acid, that is, using Lewis acid such as aluminum chloride as catalyst, fluorobenzene and terephthaloyl chloride react at a certain temperature to obtain 1,4-di(4-fluorobenzoyl)benzene. In US Pat. No. 4,968,845A, trifluoromethanesulfonic acid is used as a catalyst to catalyze the Friedel-Crafts acylation reaction of fluorobenzene and terephthaloyl chloride at 85°C. The reaction yield is 95%, and the melting point of the product is 218-221°C. This method has a high yield, but the reaction requires long-term reflux at the boiling point of fluorobenzene. The reaction temperature is high, and it is difficult to suppress the occurrence of side reactions in the system. At the same time, trifluoromethanesulfonic acid is highly corrosive, has strict requirements on equipment, and the catalyst is expensive, so this method is difficult to scale up for production.

[0005] US Patent US5300693A uses aluminum chloride as a catalyst for Friedel-Crafts acylation reaction. At 25°C-60°C, when the mass ratio of fluorobenzene, terephthaloyl chloride and aluminum chloride is 5.7:1:1.4, the yield of 1,4-di(4-fluorobenzoyl)benzene is about 95%, and the product purity is greater than 95%. In this method, aluminum chloride is used as a catalyst, and the reaction conditions are mild. Compared with trifluoromethanesulfonic acid catalyst, this method has reduced corrosion to equipment, but water is required for quenching at the end of the reaction. After quenching, a large amount of waste salt aluminum chloride hexahydrate is generated. These waste salts are difficult to handle and cause pollution to the environment. At the same time, the problem that the catalyst cannot be recycled still exists, and the catalyst consumption is large.

[0006] Chinese patent CN115135691A optimizes the purification conditions of 1,4-di(4-fluorobenzoyl)benzene, uses aluminum chloride catalyst, and obtains 1,4-di(4-fluorobenzoyl)benzene at 60°C, with a product yield of 96%. Dimethylacetamide is used for crystallization, and the product purity is greater than 99.5%. This method uses dimethylacetamide to purify 1,4-di(4-fluorobenzoyl)benzene, which can remove isomer impurities in the crude product of 1,4-di(4-fluorobenzoyl)benzene and obtain a product with a purity greater than 99.5%. However, a large amount of waste salt is generated after the aluminum chloride catalyst is quenched, and the problem that the aluminum chloride catalyst cannot be recycled has not been solved.

[0007] From the above analysis of the problems in the prior art, it can be seen that the above-mentioned known reactions either generate a large amount of waste and wastewater, or have strict requirements on equipment conditions, or are not feasible on an industrial scale. Currently, there is no low-cost, green, environmentally friendly, simple and efficient industrial method for preparing 1,4-di(4-fluorobenzoyl)benzene.

[0008] In view of the above problems in the prior art, the present invention combines many years of design and use experience in related fields to design a new method for synthesizing 1,4-di(4-fluorobenzoyl)benzene to overcome the above defects. Summary of the invention

[0009] Aiming at the shortcomings of the existing Friedel-Crafts acylation method for synthesizing 1,4-di(4-fluorobenzoyl)benzene, the present invention provides a new method for synthesizing 1,4-di(4-fluorobenzoyl)benzene, in which Lewis acid is loaded on a carrier to catalyze the reaction of fluorobenzene and terephthaloyl chloride, the reaction can be carried out at room temperature, no waste salt is generated, the reaction is green and environmentally friendly, the catalyst can be recycled, the production cost is reduced, and the raw material conversion rate is improved.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is as follows: a new method for synthesizing 1,4-di(4-fluorobenzoyl)benzene, comprising the following steps:

[0011] (1) Adding a supported solid acid and fluorobenzene into a reaction vessel under an inert gas atmosphere;

[0012] (2) Slowly drop terephthaloyl chloride into the reaction container, and react at 5-30°C for 1-8 hours after the dropwise addition is completed to obtain 1,4-di(4-fluorobenzoyl)benzene;

[0013] (3) After the reaction is completed, purifying the mixture of step (2) to obtain purified 1,4-di(4-fluorobenzoyl)benzene;

[0014] The supported solid acid consists of a carrier and a Lewis acid;

[0015] The Lewis acid is selected from any one of aluminum chloride, ferric chloride, titanium tetrachloride, and zinc chloride;

[0016] The carrier is selected from any one of HY molecular sieve, Hβ molecular sieve, ZSM-5 molecular sieve, acid-treated K10 montmorillonite, alumina, and MCM-41 molecular sieve.

[0017] Preferably, the loading amount of the Lewis acid is 0.8 mmol / g-10 mmol / g.

[0018] Preferably, the aluminum chloride is loaded on the carrier by vapor phase sublimation or impregnation, and the iron chloride, zinc chloride and titanium tetrachloride are loaded on the carrier by impregnation.

[0019] Preferably, the mass ratio of the fluorobenzene to the supported solid acid is 20:1-4:1, and the mass ratio of the fluorobenzene to terephthaloyl chloride is 10:1-3:1.

[0020] Preferably, the mass ratio of the fluorobenzene to the supported solid acid is 8:1-6:1.

[0021] Preferably, the mass ratio of fluorobenzene to terephthaloyl chloride is 6:1-5:1.

[0022] Preferably, in step (2), terephthaloyl chloride is first heated to 85-95° C., and then terephthaloyl chloride is added dropwise into the reaction container.

[0023] Preferably, the dropping time of terephthaloyl chloride in step (2) is 10-120 min.

[0024] Preferably, the dropping time of terephthaloyl chloride in step (2) is 30-45 minutes.

[0025] Preferably, the purification step in step (3) comprises:

[0026] S1 filtration: after the reaction is completed, the mixture of step (2) is filtered to obtain a filtrate, the supported solid acid filtered out is recycled, and the filtrate is washed with water to obtain a washing liquid;

[0027] S2 extraction: fluorobenzene in the washing liquid is separated by liquid-liquid extraction, leaving a solid-liquid mixture, and fluorobenzene is recycled;

[0028] S3 centrifugation: centrifuging the solid-liquid mixture to obtain a crude product of 1,4-di(4-fluorobenzoyl)benzene;

[0029] S4 Recrystallization: Recrystallize with anhydrous ethanol to obtain purified 1,4-di(4-fluorobenzoyl)benzene.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. The supported solid acid can catalyze the reaction of fluorobenzene and terephthaloyl chloride under mild conditions to generate 1,4-di(4-fluorobenzoyl)benzene. The operation is safe and the product purity is high, which is above 97.2%. The product purity is preferably greater than 99.5%. The supported solid acid can be separated from the system by filtration after the reaction. No waste salt is generated in the post-reaction treatment, which is green and environmentally friendly.

[0032] 2. The supported solid acid is prepared by the vapor phase method or the impregnation method according to the different Lewis acids loaded. The Lewis acid is firmly bound to the carrier and is not easy to fall off. It can be recycled for more than 10 times without obvious attenuation of the catalyst activity. DETAILED DESCRIPTION

[0033] In order to facilitate understanding by those skilled in the art, the present invention is further described below in conjunction with specific embodiments.

[0034] (1) Under inert gas, add supported solid acid and fluorobenzene into a reaction container and stir, wherein the mass ratio of fluorobenzene to supported solid acid is 20:1-4:1;

[0035] (2) heating terephthaloyl chloride to 85-95°C and slowly dripping it into the reaction container through a metering pump. The dripping time is 10-120 minutes. The mass ratio of fluorobenzene to terephthaloyl chloride is 10:1-3:1. After the dripping is completed, the reaction is carried out at 5-30°C for 1-8 hours. Fluorobenzene and terephthaloyl chloride react to obtain 1,4-di(4-fluorobenzoyl)benzene;

[0036] (3) The purification steps include:

[0037] S1 filtration: filtering the mixture after the reaction in step (2) to obtain a filtrate, recycling the supported solid acid, washing the obtained filtrate with water to obtain a washing liquid, wherein the mass ratio of fluorobenzene to water is 0.3:1-1:1;

[0038] S2 extraction: through liquid-liquid extraction and stratification operation, fluorobenzene in the washing liquid is separated, leaving a solid-liquid mixture, and fluorobenzene is recycled after dehydration;

[0039] S3 centrifugation: centrifuge the solid-liquid mixture after extraction to obtain a white solid, a crude product of 1,4-di(4-fluorobenzoyl)benzene;

[0040] S4 Recrystallization: The crude 1,4-di(4-fluorobenzoyl)benzene product is dried and then recrystallized with anhydrous ethanol to obtain 1,4-di(4-fluorobenzoyl)benzene with a purity of more than 97.2%. After the conditions are optimized, the product purity is more than 99.5%, the melting point is 220-222°C, and the yield can be stabilized at more than 96%.

[0041] The supported solid acid is composed of a Lewis acid and a carrier, and the Lewis acid is preferably any one of aluminum chloride, ferric chloride, titanium tetrachloride, and zinc chloride. The carrier is preferably any one of HY molecular sieve, Hβ molecular sieve, ZSM-5 molecular sieve, acid-treated K10 montmorillonite, alumina, and MCM-41 molecular sieve. The loading amount of the Lewis acid is preferably 0.8mmol / g-10mmol / g. The supported solid acid is a particle of 4-6 mesh. The supported solid acid is recycled for more than 10 times, and the product yield and purity increase with the increase in the number of times the catalyst is used without obvious attenuation. The supported solid catalyst has good stability.

[0042] Specifically, according to the difference of Lewis acid, the Lewis acid is loaded on the carrier by vapor sublimation or impregnation, and the stability of the connection between Lewis acid and the carrier is improved. Aluminum chloride is loaded on the carrier by vapor sublimation or impregnation, and ferric chloride, zinc chloride and titanium tetrachloride are loaded on the carrier by impregnation. Both vapor sublimation and impregnation are prior art, and those skilled in the art are aware of them, and will not be described in detail here. Inert gas is selected from any one or more of nitrogen, argon and helium.

[0043] In step (2) of the present invention, after terephthaloyl chloride is heated to 85-95° C., terephthaloyl chloride becomes liquid and can be smoothly dripped into a reaction container to react with fluorobenzene. The reaction conditions are mild and the reaction can be carried out at 5-30° C. Under the catalysis of a supported solid acid catalyst, a high-purity product can be obtained. After the reaction is completed, the supported solid acid is separated from the reaction system by filtration, and no water quenching is required, and a large amount of waste liquid will not be generated. The reaction is green and environmentally friendly and can be industrially produced.

[0044] The present invention adds water to the filtrate, performs liquid-liquid extraction and stratification, and the reaction product is precipitated from the organic phase. The remaining fluorobenzene phase in the reaction system is stratified from the water phase. The fluorobenzene phase can be returned to the reaction system after purification, and the supported solid acid and excess fluorobenzene can be reused in the reaction system, thereby reducing production costs.

[0045] The preferred scheme of the present invention is: under nitrogen atmosphere, fluorobenzene and supported solid acid are added to the reaction container and stirred, the mass ratio of fluorobenzene to supported solid acid is 8:1-6:1, terephthaloyl chloride is heated to 90°C, and added dropwise to the reaction container through a metering pump, the dropping time is 30-45min, the mass ratio of fluorobenzene to terephthaloyl chloride is 6:1-5:1, and after the dropwise addition is completed, the reaction is carried out at 15-20°C for 4-5h. After the reaction is completed, the reaction system is filtered to obtain a filtrate, the separated supported solid acid is recycled, and water is added to the filtrate to wash to obtain a washing liquid, and the mass ratio of fluorobenzene to water is 0.4:1-0.6:1. The washing liquid is subjected to liquid-liquid extraction and stratification operation to separate the fluorobenzene in the system, leaving a solid-liquid mixture, and the fluorobenzene is recycled after dehydration. The solid-liquid mixture is centrifuged to obtain a white solid substance, a crude product of 1,4-di(fluorobenzoyl)benzene. 1,4-di(fluorobenzoyl)benzene is recrystallized by anhydrous ethanol to obtain purified 1,4-di(fluorobenzoyl)benzene with a melting point of 220-221° C., a purity of 99.5%-99.8%, and a yield of 96.2%-99.1%.

[0046] The specific embodiments are as follows:

[0047] HY molecular sieve gas phase sublimation method loaded with aluminum chloride:

[0048] In a glove box, a certain amount of aluminum chloride was weighed and added into a 100 mL hydrothermal autoclave. A stainless steel mesh with a pore size of 1 mm was placed above the aluminum chloride. The activated HY molecular sieve was placed on the stainless steel mesh and sealed. The hydrothermal autoclave was placed in a muffle furnace and reacted at 250°C for 4 hours. After the reaction was completed, it was cooled to room temperature to obtain an aluminum chloride catalyst with HY molecular sieve as a carrier. By changing the mass ratio of aluminum chloride to molecular sieve in the hydrothermal autoclave, supported solid acids with [m(Al):m(HY)] of 0.2, 0.4, 0.6 and 0.8 were obtained, respectively, and recorded as A1, B1, C1 and D1, all of which were prepared into catalysts with a particle size of 5 mesh.

[0049] Example 1

[0050] Using A1 catalytic reaction:

[0051] (1) Under nitrogen protection, add 2 kg of A1 and 12 kg of fluorobenzoate into a 20 L reactor and stir;

[0052] (2) Heat 2 kg of terephthaloyl chloride to 85°C. Terephthaloyl chloride is in liquid state. Slowly add terephthaloyl chloride to the reactor dropwise for 30 min. The reaction temperature is 10°C and the reaction time is 8 h.

[0053] (3) After the reaction is completed, the mixture of step (2) is filtered to obtain a filtrate, and A1 is recycled; water is added to the filtrate to wash to obtain a washing liquid, wherein the mass ratio of fluorobenzene to water is 0.4:1; the washing liquid is subjected to a liquid-liquid extraction and stratification operation to separate the fluorobenzene in the system, leaving a solid-liquid mixture, and the fluorobenzene is recycled after dehydration, and the solid-liquid mixture is centrifuged to obtain a white solid 1,4-di(4-fluorobenzoyl)benzene crude product, and the crude product is dried and recrystallized using anhydrous ethanol to obtain purified 1,4-di(4-fluorobenzoyl)benzene.

[0054] Example 2

[0055] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 1. The difference from Example 1 is the reaction temperature and reaction time. In Example 2, the reaction temperature of step (2) is 20° C. and the reaction time is 6 h.

[0056] Example 3

[0057] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 1. The difference from Example 1 is that the dropping time of terephthaloyl chloride, the reaction temperature and the reaction time are different. In step (2) of Example 3, the dropping time of terephthaloyl chloride is 60 min, the reaction temperature is 30° C., and the reaction time is 4 h.

[0058] Example 4

[0059] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 1, except that the catalyst and reaction temperature were different from those of Example 1. In Example 4, B1 was used as the catalyst, and the reaction temperature was 15°C.

[0060] Example 5

[0061] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 1, except that the catalyst, the time of adding terephthaloyl chloride, the reaction temperature and the reaction time were different from those of Example 1. In Example 5, B1 was used as the catalyst, the time of adding terephthaloyl chloride in step (2) was 60 min, the reaction temperature was 25° C., and the reaction time was 3 h.

[0062] Example 6

[0063] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 1. The difference from Example 1 is that the catalyst, reaction temperature and reaction time are different. In Example 6, C1 is used as the catalyst, the reaction temperature in step (2) is 15° C., and the reaction time is 4 h.

[0064] Example 7

[0065] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 1. The difference from Example 1 is that the catalyst, the time for adding terephthaloyl chloride, the reaction temperature and the reaction time are different. In Example 7, C1 is used as the catalyst, the time for adding terephthaloyl chloride in step (2) is 60 min, the reaction temperature is 20° C., and the reaction time is 1 h.

[0066] Example 8

[0067] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 1. The difference from Example 1 is the catalyst and the reaction time. In Example 8, D1 was used as the catalyst, and the reaction time in step (2) was 4 h.

[0068] Example 9

[0069] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 1. The difference from Example 1 is that the catalyst, reaction temperature and reaction time are different. In Example 9, D1 is used as the catalyst, the reaction temperature in step (2) is 15° C., and the reaction time is 3 h.

[0070] The yield and purity of 1,4-di(4-fluorobenzoyl)benzene obtained in Example 1-9 were detected by gas chromatography. The detection results are shown in Table 1:

[0071] Table 1 Test data of products obtained from Examples 1-9

[0072]

[0073] Impregnation method for loading ferric chloride on molecular sieve ZSM-5

[0074] Take 150g of anhydrous chloroform and add it to a 500mL three-necked flask. Add 15g of ZSM-5 molecular sieve into the three-necked flask under the protection of nitrogen atmosphere, add 3g of anhydrous ferric chloride, stir mechanically, reflux for 10h, cool to room temperature after reflux, remove chloroform by vacuum distillation, and place the product in an oven at 120℃ and dry for 4h to obtain a finished FeCl3 / ZSM-5 catalyst with a loading rate of 1.2mmol / g.cat., which is placed in a dryer for standby use.

[0075] Example 10

[0076] (1) Weigh 2 kg of ZSM-5 loaded with ferric chloride and add it into a 20 L reactor under helium protection, then add 8 kg of fluorobenzene and stir;

[0077] (2) Heat terephthaloyl chloride to 90°C. Terephthaloyl chloride is a liquid. Slowly drop 1.5 kg of terephthaloyl chloride into the reactor. The drop-adding time is 10 min. The reaction temperature is 20°C and the reaction time is 8 h.

[0078] (3) After the reaction is completed, the mixture of step (2) is filtered to obtain a filtrate, and the filtered catalyst is recycled; water is added to the filtrate to wash to obtain a washing liquid, wherein the mass ratio of fluorobenzene to water is 0.5:1; the washing liquid is subjected to a liquid-liquid extraction and stratification operation to separate the fluorobenzene in the system and retain the solid-liquid mixture, and the fluorobenzene is recycled after dehydration; the solid-liquid mixture is centrifuged to obtain a white solid 1,4-di(4-fluorobenzoyl)benzene crude product; the 1,4-di(4-fluorobenzoyl)benzene crude product is dried and then recrystallized with ethanol to obtain purified 1,4-di(4-fluorobenzoyl)benzene with a purity of 99.2%, a product yield of 96.8% and a melting point of 220.28°C.

[0079] Loading Titanium Tetrachloride on Acid-treated K10 Montmorillonite by Impregnation Method

[0080] 10 mL of titanium tetrachloride and 200 mL of anhydrous carbon disulfide were added to a three-necked flask, and 10 g of acid-treated K10 montmorillonite was added under stirring. The reaction was refluxed for 24 hours, and then the solvent was evaporated under reduced pressure. The catalyst was washed with acetone and ether in turn and dried to obtain a titanium tetrachloride-loaded K10 montmorillonite catalyst with a loading amount of 8 mmol / g.

[0081] Embodiment 11

[0082] (1) Under nitrogen protection, weigh 0.5 kg of titanium tetrachloride-supported montmorillonite catalyst and 10 kg of fluorobenzene, add them into a 10 L reactor and stir;

[0083] (2) Heat 1 kg of terephthaloyl chloride to 95°C. Terephthaloyl chloride is a liquid and is slowly added dropwise to the reactor. The addition time is 45 min. The reaction temperature is 30°C and the reaction time is 5 h.

[0084] (3) After the reaction is completed, the reaction mixture of step (2) is filtered to obtain a filtrate, and the filtered catalyst is recycled; water of equal mass to fluorobenzene is added to the filtrate to wash to obtain a washing liquid; fluorobenzene in the system is separated by liquid-liquid extraction and stratification operation, and a solid-liquid mixture is retained, and the fluorobenzene is recycled after dehydration; the solid-liquid mixture is centrifuged to obtain a white solid 1,4-di(4-fluorobenzoyl)benzene crude product; the crude product is dried and recrystallized with anhydrous ethanol to obtain 1,4-di(4-fluorobenzoyl)benzene. The finished product is tested by gas chromatography, and the purity is 97.2%, the yield is 95.4%, and the melting point is 220.02°C.

[0085] Hβ molecular sieve loaded with zinc chloride by impregnation method

[0086] 5.6 g of zinc chloride was dissolved in 200 mL of ethanol, and then 10 g of Hβ molecular sieve was added into a three-necked flask, mechanically stirred, refluxed for 24 h, cooled to room temperature and filtered, the catalyst was washed with chloroform and ether several times, and vacuum dried at 40°C to obtain ZnCl2 / Hβ catalyst with a loading of 4 mmol / g.

[0087] Example 12

[0088] (1) Under nitrogen protection, take 1 kg of ZnCl2 / Hβ catalyst and 7 kg of fluorobenzene, add them into a 10 L reactor and stir;

[0089] (2) Heat 1.2 kg of terephthaloyl chloride to 95°C and slowly drip it into the reactor. The dripping time is 60 minutes. After the dripping is completed, react at 5°C for 8 hours;

[0090] (3) After the reaction is completed, the mixture of step (2) is filtered to obtain a filtrate, the filtered ZnCl2 / Hβ catalyst is recycled, and an equal amount of water is added to the filtrate for washing; the fluorobenzene in the system is separated by liquid-liquid extraction and stratification operation, and the solid-liquid mixture is retained, and the fluorobenzene is recycled after dehydration; the solid-liquid mixture is centrifuged to obtain a white solid substance 1,4-di(4-fluorobenzoyl)benzene crude product, and the 1,4-di(4-fluorobenzoyl)benzene crude product is dried and recrystallized using anhydrous ethanol to obtain 1,4-di(4-fluorobenzoyl)benzene with a purity of 98.2%, a product yield of 91.4%, and a melting point of 220.04°C.

[0091] HY molecular sieve loaded with aluminum chloride by impregnation method

[0092] Different masses of aluminum chloride were dissolved in 200 mL of ethanol and then poured into a three-necked flask. HY molecular sieve was added into the three-necked flask, mechanically stirred, and refluxed for 24 hours. After the reaction was completed, it was cooled to room temperature and filtered. The catalyst was washed with chloroform and ether for multiple times and dried in vacuo at 40°C to obtain the catalyst AlCl3 / HY. By adjusting the mass ratio of aluminum chloride to HY molecular sieve, supported solid acids with [m(Al):m(HY)] of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9 were obtained, which were recorded as A2, B2, C2, D2, E2, F2, G2, H2, and I2, and all were prepared into 6-mesh granular catalysts.

[0093] Embodiment 13

[0094] (1) Under nitrogen protection, take 1 kg of A2 catalyst and 8 kg of fluorobenzene, add them into a 10 L reactor, and start stirring;

[0095] (2) Heat 2.7 kg of terephthaloyl chloride to 95°C and then slowly add it dropwise to the reactor. The addition time is 120 min, the reaction temperature is 20°C, and the reaction time is 8 h.

[0096] (3) After the reaction is completed, the mixture of step (2) is filtered to obtain a filtrate, the filtered A2 is recycled, and an equal amount of water is added to the filtrate for washing; the fluorobenzene in the system is separated by liquid-liquid extraction and stratification operation, and the solid-liquid mixture is retained, and the fluorobenzene is recycled after dehydration; the solid-liquid mixture is centrifuged to obtain a white solid substance 1,4-di(4-fluorobenzoyl)benzene crude product, and the 1,4-di(4-fluorobenzoyl)benzene crude product is dried and recrystallized using anhydrous ethanol to obtain 1,4-di(4-fluorobenzoyl)benzene.

[0097] Embodiment 14

[0098] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 13. The difference from Example 13 is that the catalyst, reaction temperature and reaction time are different. In Example 14, B2 is used as the catalyst, the reaction temperature in step (2) is 20° C., and the reaction time is 7 h.

[0099] Embodiment 15

[0100] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 13. The difference from Example 13 is that the catalyst, the dropping time of terephthaloyl chloride, the reaction temperature and the reaction time are different. In Example 15, C2 is used as the catalyst, the dropping time of terephthaloyl chloride in step (2) is 40 min, the reaction temperature is 30° C., and the reaction time is 6 h.

[0101] Example 16

[0102] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 13. The difference from Example 13 is the catalyst and reaction time. In Example 16, D2 was used as the catalyst, and the reaction time in step (2) was 5 h.

[0103] Embodiment 17

[0104] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 13. The difference from Example 13 is that the catalyst, reaction temperature and reaction time are different. In Example 17, E2 is used as the catalyst, the reaction temperature in step (2) is 20° C., and the reaction time is 4 h.

[0105] Embodiment 18

[0106] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 13. The difference from Example 13 is that the catalyst, reaction temperature and reaction time are different. In Example 18, F2 is used as the catalyst, the reaction temperature in step (2) is 30° C., and the reaction time is 4 h.

[0107] Embodiment 19

[0108] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 13. The difference from Example 13 is that the catalyst, reaction temperature and reaction time are different. In Example 19, G2 is used as the catalyst, the reaction temperature in step (2) is 10° C., and the reaction time is 3 h.

[0109] Embodiment 20

[0110] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 13. The difference from Example 13 is that the catalyst, reaction temperature and reaction time are different. In Example 20, H2 is used as the catalyst, the reaction temperature in step (2) is 20°C, and the reaction time is 3h.

[0111] Embodiment 21

[0112] 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps of Example 13. The difference from Example 13 is that the catalyst, reaction temperature and reaction time are different. In Example 21, I2 is used as the catalyst, the reaction temperature in step (2) is 30°C, and the reaction time is 3h.

[0113] The products of Examples 13-21 were tested using gas chromatography. The test results are shown in Table 2.

[0114] Table 2 Test results of the products obtained in Examples 13-21

[0115]

[0116] According to the test results of Examples 1-21, the 1,4-di(4-fluorobenzoyl)benzene prepared by the present invention has a high product yield and purity, with a yield of ≥91.4% and a purity of ≥97.2%. When reacted under the catalyst and reaction conditions of the preferred embodiment, the product yield is ≥96.7% and the purity is ≥99.5%, indicating that the supported solid acid in the present invention has a good catalytic effect on the reaction of fluorobenzene and terephthaloyl chloride. After the catalytic reaction of the present invention is completed, the supported solid acid is separated from the reaction system by filtration, and a large amount of water does not need to be added for quenching, and the post-reaction treatment will not affect the environment.

[0117] Catalyst stability test:

[0118] Test 1: 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps in Example 1, except that the catalyst was A1 which was separated and reused 4 times. The yield of 1,4-di(4-fluorobenzoyl)benzene was 96.4% and the purity was 99.5%.

[0119] Test 2: 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps in Example 6, except that the catalyst was C1 used 8 times after separation, and the yield of 1,4-di(4-fluorobenzoyl)benzene was 98.5% and the purity was 99.5%.

[0120] Test 3: 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps in Example 10, except that the catalyst was FeCl3 / ZSM-5 which was separated and reused 10 times. The yield of 1,4-di(4-fluorobenzoyl)benzene was 96.5% and the purity was 99.3%.

[0121] Test 4: 1,4-di(4-fluorobenzoyl)benzene was prepared according to the steps in Example 11, except that the catalyst was a titanium tetrachloride-loaded montmorillonite catalyst used 10 times after separation, and the yield of 1,4-di(4-fluorobenzoyl)benzene was 95.1% and the purity was 97.1%.

[0122] It can be seen from Tests 1-4 that the supported solid acid in the present invention still has a good catalytic effect after multiple uses, indicating that the supported solid acid has good stability when applied to the reaction of fluorobenzene and terephthaloyl chloride.

[0123] It should be understood that the purpose of these embodiments is only to illustrate the present invention and is not intended to limit the protection scope of the present invention. In addition, it should also be understood that after reading the technical content of the present invention, those skilled in the art can make various changes, modifications and / or variations to the present invention, and all of these equivalent forms also fall within the protection scope defined by the claims attached to this application.

Claims

1. A method for synthesizing 1,4-di(4-fluorobenzoyl)benzene, characterized in that: The following steps are involved: (1) adding a supported solid acid and fluorobenzene into a reaction vessel under an inert atmosphere; (2) Slowly drop terephthaloyl chloride into the reaction container, and react at 5-30°C for 1-8 hours after the dropwise addition is completed to obtain 1,4-di(4-fluorobenzoyl)benzene; (3) After the reaction is completed, purifying the mixture of step (2) to obtain purified 1,4-di(4-fluorobenzoyl)benzene; The supported solid acid is selected from any one of HY molecular sieve supported aluminum chloride, molecular sieve ZSM-5 supported ferric chloride, acid-treated K10 montmorillonite supported titanium tetrachloride, and Hβ molecular sieve supported zinc chloride; The loading amount of Lewis acid in the supported solid acid is 0.8 mmol / g-10 mmol / g.

2. The method for synthesizing 1,4-di(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The aluminum chloride is loaded on the carrier by a vapor phase sublimation method or an impregnation method, and the iron chloride, zinc chloride and titanium tetrachloride are loaded on the carrier by an impregnation method.

3. The method for synthesizing 1,4-di(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The mass ratio of the fluorobenzene to the supported solid acid is 20:1-4:1, and the mass ratio of the fluorobenzene to terephthaloyl chloride is 10:1-3:

1.

4. The method for synthesizing 1,4-di(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The mass ratio of the fluorobenzene to the supported solid acid is 8:1-6:

1.

5. The method for synthesizing 1,4-di(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The mass ratio of the fluorobenzene to terephthaloyl chloride is 6:1-5:

1.

6. The method for synthesizing 1,4-di(4-fluorobenzoyl)benzene according to claim 1, characterized in that: In step (2), terephthaloyl chloride is first heated to 85-95° C., and then terephthaloyl chloride is added dropwise into the reaction container.

7. The method for synthesizing 1,4-di(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The dropping time of terephthaloyl chloride in step (2) is 10-120 min.

8. The method for synthesizing 1,4-di(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The time for adding terephthaloyl chloride in step (2) is 30-45 minutes.

9. The method for synthesizing 1,4-di(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The purification step in step (3) includes: S1 filtration: after the reaction is completed, the mixture of step (2) is filtered to obtain a filtrate, the filtered supported solid acid is recycled, and the filtrate is washed with water to obtain a washing liquid; S2 extraction: fluorobenzene is separated from the washing liquid by liquid-liquid extraction, leaving a solid-liquid mixture, and fluorobenzene is recycled; S3 centrifugation: centrifuging the solid-liquid mixture to obtain a crude product of 1,4-di(4-fluorobenzoyl)benzene; S4 Recrystallization: Recrystallize with anhydrous ethanol to obtain purified 1,4-di(4-fluorobenzoyl)benzene.

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