Preparation method and application of 4, 4 '-dichlorobenzophenone

Abstract

The invention provides a preparation method and application of 4, 4 '-dichlorobenzophenone. Comprising the following steps: under the action of activated alpha-Fe2O3, carrying out acylation reaction on p-chlorobenzoyl chloride and chlorobenzene to obtain the 4, 4 '-dichlorobenzophenone. The 4, 4 '-dichlorobenzophenone is prepared by using the activated alpha-Fe2O3 as the catalyst, so that the reaction temperature can be reduced, the reaction conditions are milder, the reaction selectivity is improved, the reaction time is shortened, the generation of wastewater is reduced, and the environmental protection property is improved.

Description

Technical Field

[0001] This invention relates to a method for preparing 4,4'-dichlorobenzophenone and its application, belonging to the field of chemical synthesis technology. Background Technology

[0002] Polyetheretherketone (PEEK) materials possess excellent comprehensive properties, including heat resistance, abrasion resistance, fatigue resistance, radiation resistance, peel resistance, creep resistance, dimensional stability, impact resistance, chemical resistance, non-toxicity, and flame retardancy. They are widely used in various fields such as electronics, aerospace, automotive, energy, and other industries, as well as medical applications. Currently, PEEK is primarily used in the transportation sector globally, accounting for 40.21% of demand. In industry, electronics and information technology, medical, and other fields, PEEK demand accounts for 25.30%, 24.40%, and 10.09%, respectively. With the expansion of industrial scale, especially driven by demand in areas such as lightweighting of new energy vehicles, extending the lifespan of integrated circuits, and bone repair, the market demand for excellent engineering materials like PEEK will further increase.

[0003] 4,4'-Difluorobenzophenone (DFBP) is the core raw material for PEEK, and its purity and quality directly affect the product quality of PEEK. Currently, DFBP is mainly prepared through Friedel-Crafts alkylation hydrolysis, Friedel-Crafts acylation, 4,4'-diaminodiphenylmethane diazotization oxidation, phosgene-catalyzed acylation, or fluorination of 4,4'-dichlorobenzophenone.

[0004] The Friedel-Crafts alkylation hydrolysis method involves using fluorobenzene and carbon tetrachloride as raw materials in anhydrous aluminum trichloride catalysis to first generate 4,4'-difluorophenyl dichloromethane. Unreacted carbon tetrachloride and fluorobenzene are then recovered by steam distillation. Hydrolysis at low temperature yields a crude product, which is then distilled and recrystallized to obtain DFBP. However, the DFBP obtained by this method contains the isomer 2,4'-difluorobenzophenone, which is difficult to separate and has a low reaction yield. Furthermore, the raw material carbon tetrachloride has a serious destructive effect on atmospheric ozone. Additionally, using aluminum trichloride as a Friedel-Crafts catalyst generates a large amount of aluminum-containing wastewater, posing a significant environmental burden.

[0005] The Friedel-Crafts acylation method involves reacting fluorobenzene with p-fluorobenzoyl halide (or p-fluorobenzoic acid) under Lewis acid catalysis to produce 4,4′-difluorobenzophenone. This method suffers from high raw material prices and tight supply, resulting in high synthesis costs. Furthermore, the use of aluminum trichloride as the Friedel-Crafts catalyst generates large amounts of aluminum-containing wastewater, posing significant environmental challenges.

[0006] Phosgene-catalyzed acylation method includes: direct acylation condensation of fluorobenzene with phosgene to obtain DFBP. Although the method is simple, in addition to 4,4'-difluorobenzophenone, the product also contains a quarter of the isomer 2,4'-difluorobenzophenone, which is difficult to separate and has a low yield. In addition, the raw material phosgene is highly toxic, making its use and control difficult.

[0007] The diazotization oxidation method for 4,4'-diamino-diphenylmethane involves diazotizing 4,4'-diamino-diphenylmethane in anhydrous or concentrated hydrogen fluoride aqueous solution, followed by thermal decomposition of the resulting diazotized fluoride in the presence of nitrous acid or nitrite ions as an oxidant, yielding 4,4'-difluorobenzophenone. However, diazonium salts decompose readily at slightly above room temperature, and the intense exothermic reaction accelerates the decomposition rate. Controlling the exothermic reaction during large-scale production poses an explosion hazard. Furthermore, the reaction utilizes large amounts of HF, resulting in severe equipment corrosion and a harsh operating environment.

[0008] The fluorination method for 4,4'-dichlorobenzophenone mainly involves fluorinating 4,4'-dichlorobenzophenone to obtain 4,4'-difluorobenzophenone. However, the existing methods for obtaining 4,4'-dichlorobenzophenone not only have high reaction temperatures and long reaction times, but also low selectivity. Furthermore, the use of aluminum trichloride as a catalyst generates a large amount of aluminum-containing wastewater, which poses a significant environmental challenge. Summary of the Invention

[0009] This invention provides a method for preparing 4,4'-dichlorobenzophenone, which uses activated α-Fe2O3 as a catalyst. This method can lower the reaction temperature, make the reaction conditions milder, improve the selectivity of the reaction, shorten the reaction time, reduce wastewater generation, and improve environmental friendliness.

[0010] This invention provides a method for preparing 4,4'-difluorobenzophenone. The 4,4'-dichlorobenzophenone prepared by the above method is fluorinated to prepare 4,4'-difluorobenzophenone. Therefore, this preparation method has the advantages of low cost, high yield, low risk and low waste.

[0011] This invention provides a method for preparing polyether ether ketone (PEEK). PEEK is prepared using 4,4'-difluorobenzophenone obtained by the above method. Therefore, this method has low production cost, low preparation risk, high yield, and excellent environmental performance, making it suitable for widespread application.

[0012] The present invention provides a method for preparing 4,4'-dichlorobenzophenone, comprising: acylation reaction of p-chlorobenzoyl chloride and chlorobenzene under the action of activated α-Fe2O3 to obtain 4,4'-dichlorobenzophenone.

[0013] In the preparation method of 4,4'-dichlorobenzophenone as described above, the acylation reaction is carried out at a temperature of 20-100°C for a time of 0.5-4 h; and / or,

[0014] The molar ratio of p-chlorobenzoyl chloride to chlorobenzene is not higher than 1:1.1; and / or,

[0015] The molar ratio of p-chlorobenzoyl chloride to the activated α-Fe2O3 is not higher than 1:0.01.

[0016] The method for preparing 4,4'-dichlorobenzophenone as described above further includes a post-treatment after the acylation reaction, the post-treatment comprising:

[0017] Add a non-aqueous solvent to the solution after the acylation reaction to obtain the first system;

[0018] The first system was filtered to obtain recovered α-Fe2O3 and an organic phase.

[0019] The organic phase was washed with an acid-base regulator and then concentrated, recrystallized, and dried sequentially to obtain the 4,4'-dichlorobenzophenone.

[0020] The recovered α-Fe2O3 is returned to participate in the acylation reaction.

[0021] In the preparation method of 4,4'-dichlorobenzophenone as described above, the non-water-soluble solvent includes at least one of dichloromethane, dichloroethane, ethyl acetate, toluene, and chlorobenzene;

[0022] And / or,

[0023] The acid-base regulator includes at least one of sodium bicarbonate, sodium carbonate, ammonium bicarbonate, sodium hydroxide, and potassium hydroxide solution.

[0024] In another aspect, the present invention provides a method for preparing 4,4'-difluorobenzophenone, comprising: fluorinating 4,4'-dichlorobenzophenone to obtain 4,4'-difluorobenzophenone;

[0025] The 4,4'-dichlorobenzophenone was prepared by the method described above.

[0026] The 4,4'-difluorobenzophenone preparation method described above involves fluorination treatment with a fluorinating agent to obtain the 4,4'-difluorobenzophenone.

[0027] The fluorinating agent is obtained by reacting a fluorine source with R4YCl;

[0028] The fluorine source is selected from at least one of potassium fluoride, hydrogen fluoride, triethylamine hydrofluoride, and pyridine hydrofluoride; and / or,

[0029] In R4YCl, R is selected from at least one of methyl, ethyl, propyl, butyl, phenyl, and benzyl, and Y is N or P.

[0030] In the preparation method of 4,4'-difluorobenzophenone as described above, R4YCl is selected from at least one of tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetraphenylammonium chloride, tetramethylphosphine chloride, tetraethylphosphine chloride, tetrapropylphosphine chloride, tetrabutylphosphine chloride, and tetraphenylphosphine chloride.

[0031] In the preparation method of 4,4'-difluorobenzophenone as described above, the molar ratio of Cl atoms in R4YCl to F atoms in the fluorine source is not higher than 1:1; and / or,

[0032] In the fluorination treatment, the reaction temperature is 150-250℃ and the reaction time is 5-12h.

[0033] In the preparation method of 4,4'-difluorobenzophenone as described above, the molar ratio of 4,4'-dichlorobenzophenone to the fluorinating agent is not higher than 1:2.

[0034] In another aspect, the present invention provides a method for preparing polyetheretherketone, wherein the polyetheretherketone is prepared by 4,4'-difluorobenzophenone;

[0035] The 4,4'-difluorobenzophenone was prepared by the method described above.

[0036] The method for preparing 4,4'-dichlorobenzophenone of the present invention uses activated α-Fe2O3 as a catalyst, which can reduce the reaction temperature, make the reaction conditions milder, improve the selectivity of the reaction, shorten the reaction time, reduce the generation of wastewater, and improve environmental protection.

[0037] This invention provides a method for preparing 4,4'-difluorobenzophenone. 4,4'-difluorobenzophenone is prepared from 4,4'-difluorodiphenylmethane obtained by the above method. Therefore, this preparation method has the advantages of low cost, high yield, low risk, and low waste.

[0038] This invention provides a method for preparing polyether ether ketone (PEEK). PEEK is prepared using 4,4'-difluorobenzophenone obtained by the above method. Therefore, this method has low production cost, low preparation risk, high yield, and excellent environmental performance, making it suitable for widespread application. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 The 4,4'-dichlorobenzophenone in Example 1a of this invention 1 H NMR spectrum;

[0041] Figure 2 The 4,4'-dichlorobenzophenone in Example 1a of this invention 13 C NMR spectrum;

[0042] Figure 3 The 4,4'-difluorobenzophenone in Example 1b of this invention 1 H NMR spectrum;

[0043] Figure 4 The 4,4'-difluorobenzophenone in Example 1b of this invention 13 C10 NMR spectrum. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0045] The present invention provides a method for preparing 4,4'-dichlorobenzophenone, comprising: acylation reaction of p-chlorobenzoyl chloride and chlorobenzene under the action of activated α-Fe2O3 to obtain 4,4'-dichlorobenzophenone.

[0046] This invention does not impose any particular limitation on the activation of α-Fe₂O₃; α-Fe₂O₃ can be activated using methods commonly used in the art. In some embodiments, activated α-Fe₂O₃ is prepared by a method comprising the following steps: ultrasonically dispersing α-Fe₂O₃ in water, followed by baking, thereby obtaining activated α-Fe₂O₃. In some embodiments, the ultrasonic dispersion frequency can be 15-30 kHz, and the time can be 30-90 min; the baking temperature can be 150-300 °C, and the time can be 24-72 h.

[0047] This invention uses p-chlorobenzoyl chloride and chlorobenzene as raw materials and activated α-Fe2O3 as a catalyst to prepare 4,4'-dichlorobenzophenone. The reaction conditions are very mild and the selectivity is high.

[0048] Furthermore, due to the presence of a large number of positively charged Fe ions on the surface of α-Fe₂O₃, chloride ions generated in situ during the acylation reaction are adsorbed onto the micropores or outer surface of α-Fe₂O₃, forming a negatively charged layer on the catalyst surface. The attraction between the negatively charged catalyst and the positively charged acyl ions causes the acyl ions to form a second positively charged layer on the α-Fe₂O₃ surface. This adsorption of α-Fe₂O₃ creates a salting-out effect, simply repelling organic products on the α-Fe₂O₃ surface and protecting the catalyst from any foreign substances. Therefore, this invention allows for the separation and recycling of α-Fe₂O₃. The separation process is simple, and the resulting α-Fe₂O₃ has high catalytic efficiency, greatly improving catalyst utilization efficiency. Compared with using AlCl₃ as a catalyst, using activated α-Fe₂O₃ also has the advantage of not generating large amounts of wastewater, exhibiting excellent environmental performance.

[0049] In some embodiments of the present invention, when the temperature is 20-100°C and the time is 0.5-4h during the acylation reaction, the generated byproduct HCl is less likely to react with the catalyst, which is beneficial for the recovery and utilization of the catalyst and can also improve the reaction efficiency of the acylation reaction, thereby increasing the yield of 4,4'-dichlorobenzophenone.

[0050] Furthermore, since the main product of the acylation reaction is a solid, when the molar ratio of p-chlorobenzoyl chloride to chlorobenzene is not higher than 1:1.1, part of the chlorobenzene participates in the acylation reaction, and the other part is used as a solvent in the reaction system. As the acylation reaction proceeds, the reaction system still has excellent mass transfer ability, which can improve the yield of 4,4'-dichlorobenzophenone. Preferably, the molar ratio of p-chlorobenzoyl chloride to chlorobenzene is 1:(1.1~5). When the molar ratio of p-chlorobenzoyl chloride to chlorobenzene is lower than 1:5, that is, when the molar amount of p-chlorobenzoyl chloride is 1 and the molar amount of chlorobenzene is higher than 5, the effect on the reaction yield is relatively small.

[0051] When the molar ratio of p-chlorobenzoyl chloride to activated α-Fe₂O₃ is not higher than 1:0.01, the acylation reaction between p-chlorobenzoyl chloride and chlorobenzene can be more fully promoted under milder conditions, further increasing the yield of 4,4'-dichlorobenzophenone. Preferably, the molar ratio of p-chlorobenzoyl chloride to activated α-Fe₂O₃ is 1:(0.01~0.2). When the molar amount of p-chlorobenzoyl chloride is 1 and the molar amount of activated α-Fe₂O₃ is higher than 0.2, the effect on the reaction yield is relatively small.

[0052] In some embodiments of the present invention, a post-treatment is further included after the acylation reaction, the post-treatment including: adding a non-water-soluble solvent to the solution after the acylation reaction to obtain a first system;

[0053] The first system was filtered to obtain recovered α-Fe2O3 and an organic phase.

[0054] The organic phase was washed with an acid-base regulator and then concentrated, recrystallized, and dried to obtain 4,4'-dichlorobenzophenone.

[0055] α-Fe2O3 is recovered and returned to participate in the acylation reaction.

[0056] In this invention, after the acylation reaction, a solution containing 4,4'-dichlorobenzophenone and a catalyst is obtained. A non-water-soluble solvent is added to the solution containing 4,4'-dichlorobenzophenone and the catalyst to completely dissolve the 4,4'-dichlorobenzophenone, thus obtaining a first system. The first system is then filtered to obtain a solid-phase recovered α-Fe2O3 and an organic phase. The recovered α-Fe2O3 can be returned to participate in the acylation reaction. Next, the organic phase is washed with an acid-base adjuster to make it neutral. Finally, it is concentrated, recrystallized, and dried sequentially to obtain 4,4'-dichlorobenzophenone.

[0057] In some embodiments, the non-water-soluble solvent includes, but is not limited to, at least one of dichloromethane, dichloroethane, ethyl acetate, toluene, and chlorobenzene; the acid-base adjuster includes, but is not limited to, at least one of sodium bicarbonate, sodium carbonate, ammonium bicarbonate, sodium hydroxide, and potassium hydroxide.

[0058] In some embodiments, the recovered α-Fe₂O₃ can be washed multiple times with dichloromethane to remove the 4,4'-dichlorobenzophenone solution from its surface, resulting in purer recovered α-Fe₂O₃ and more complete collection of the 4,4'-dichlorobenzophenone solution. The washed organic phase is then recovered and washed with sodium bicarbonate solution to neutralize it. Finally, it undergoes concentration, recrystallization, and drying to obtain 4,4'-dichlorobenzophenone. Further, the washing process can be repeated 2-3 times.

[0059] In some embodiments, the recovered α-Fe₂O₃ can be treated with 10 wt% hydrogen peroxide and then activated to obtain activated α-Fe₂O₃ that can participate in the acylation reaction. The activation treatment includes: ultrasonically dispersing the recovered α-Fe₂O₃ in water and then baking it to obtain activated α-Fe₂O₃.

[0060] This invention, through post-processing after acylation, can yield 4,4'-dichlorobenzophenone with higher purity, which is helpful for subsequent synthesis of products with higher purity. Furthermore, it can recover the catalyst, allowing it to participate in the acylation reaction again, thereby improving the utilization rate of raw materials and saving production costs.

[0061] A second aspect of the present invention provides a method for preparing 4,4'-difluorobenzophenone, comprising: adding a fluorinating agent to compound C and subjecting it to fluorination treatment to obtain 4,4'-difluorobenzophenone;

[0062] Compound C was prepared by the method for preparing 4,4'-dichlorobenzophenone described in the first aspect.

[0063] It is understandable that compound C is 4,4'-dichlorobenzophenone.

[0064] Specifically, the 4,4'-dichlorobenzophenone prepared by the method of the first aspect is subjected to fluorination treatment to convert the chlorine element in the 4,4'-dichlorobenzophenone into the F element, thereby obtaining 4,4'-difluorobenzophenone.

[0065] The method for preparing 4,4'-difluorobenzophenone of the present invention includes fluorinating 4,4'-dichlorobenzophenone prepared by the method of the first aspect to obtain 4,4'-difluorobenzophenone. Therefore, this preparation method has the advantages of low cost, high yield, low risk and low waste.

[0066] In some embodiments of the present invention, fluorination is performed using a fluorinating agent to obtain 4,4'-difluorobenzophenone;

[0067] The fluorinating agent is obtained by reacting a fluorine source with R4YCl;

[0068] The fluorine source is selected from at least one of potassium fluoride, hydrogen fluoride, triethylamine hydrofluoride, and pyridine hydrofluoride;

[0069] In R4YCl, R is selected from at least one of methyl, ethyl, propyl, butyl, phenyl, and benzyl.

[0070] Y can be either N or P.

[0071] As shown in Formulas 1 and 2, the present invention uses a fluorine source to react with R4YCl to prepare a fluorinating agent, and then uses the fluorinating agent to fluorinate 4,4'-dichlorobenzophenone (the fluorination process is a homogeneous reaction) to obtain 4,4'-difluorobenzophenone.

[0072]

[0073] In some embodiments, the fluorine source and R4YCl can react in a methanol or ethanol solution, and the fluorinating agent with high purity can be obtained after filtration, concentration and vacuum drying.

[0074] In some embodiments, fluorination can be carried out in a polar aprotic solvent, and after the fluorination reaction is complete, the product can be extracted, concentrated, recrystallized, washed, and dried to obtain 4,4'-difluorobenzophenone with higher purity.

[0075] Compared to fluorination using KF, this fluorinating agent is an organofluorine compound with high fluorination activity, allowing for the fluorination of 4,4'-dichlorobenzophenone under milder conditions and shorter fluorination time. Fluorination using this agent simplifies subsequent separation, and the resulting byproducts can be more easily recovered. In some embodiments, the product can be extracted, almost completely entering the organic phase. The organic phase is then concentrated, recrystallized, washed, and dried to obtain high-purity 4,4'-difluorobenzophenone. The aqueous phase mainly contains R4YCl and a small amount of R4YF, which can be recovered and reused after concentration and drying.

[0076] In this invention, since the fluorine source and R4YCl are key raw materials for preparing fluorinating agents, R4YCl can be further selected to obtain fluorinating agents with higher activity. Exemplarily, R4YCl can be selected from at least one of tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetraphenylammonium chloride, tetramethylphosphine chloride, tetraethylphosphine chloride, tetrapropylphosphine chloride, tetrabutylphosphine chloride, and tetraphenylphosphine chloride.

[0077] Furthermore, the inventors discovered in their research that when the molar ratio of Cl atoms in R4YCl to F atoms in the fluorine source is no higher than 1:1, the fluorine source can react more fully with R4YCl, resulting in a fluorinating agent with higher purity and activity, thereby improving the efficiency of the fluorination process. Further, the molar ratio of Cl atoms in R4YCl to F atoms in the fluorine source is 1:(1-3).

[0078] In some embodiments of the present invention, when the fluorination treatment is carried out at a temperature of 150-250°C for 5-12 hours, the fluorination treatment can be carried out under milder conditions and in a shorter time, thereby improving the efficiency of the fluorination treatment and obtaining 4,4'-difluorobenzophenone with higher purity and higher yield.

[0079] The inventors also discovered that when the molar ratio of 4,4'-dichlorobenzophenone to the fluorinating agent is not higher than 1:2, the efficiency of fluorination treatment can be improved while saving the fluorinating agent, thereby allowing 4,4'-dichlorobenzophenone to be more fully converted into 4,4'-difluorobenzophenone. Further, the molar ratio of 4,4'-dichlorobenzophenone to the fluorinating agent is 1:(2-6).

[0080] A third aspect of the present invention provides a method for preparing polyetheretherketone, wherein the polyetheretherketone is prepared by 4,4'-difluorobenzophenone;

[0081] 4,4'-Difluorobenzophenone was prepared by the method described in the second aspect.

[0082] The present invention uses the preparation method of 4,4'-difluorobenzophenone in the second aspect to prepare polyether ether ketone. This method has low production cost, low preparation risk, high yield and excellent environmental performance, and is suitable for widespread application.

[0083] The present invention will now be described in detail through specific embodiments.

[0084] Example 1a

[0085] The preparation method of 4,4'-dichlorobenzophenone in this embodiment includes the following steps:

[0086] Fe2O3 was dispersed in water, sonicated at room temperature (650 kHz) for 60 min, then filtered to collect the solid powder, and the solid powder was baked at 200 °C for 72 h to obtain activated α-Fe2O3.

[0087] Activated α-Fe₂O₃, chlorobenzene, and p-chlorobenzoyl chloride were added sequentially to a reaction flask, with the molar ratio of p-chlorobenzoyl chloride to chlorobenzene being 1:3 and the molar ratio of p-chlorobenzoyl chloride to activated α-Fe₂O₃ being 1:0.05. The reaction was stirred at 40℃ for 2 h. GC analysis of the samples showed that the yield reached 96%, and the reaction produced virtually no byproduct 2,4'-dichlorobenzophenone, indicating good selectivity.

[0088] After the reaction was complete, 1 L of dichloromethane was added to completely dissolve the product, and the catalyst α-Fe₂O₃ was filtered off. The filtered α-Fe₂O₃ was washed twice with dichloromethane, the organic phases were combined, and the organic phases were washed with sodium bicarbonate solution until neutral. After concentrating and recovering the solvent dichloromethane and unreacted chlorobenzene, the product was recrystallized at low temperature with ethanol, washed, and dried under vacuum to obtain 4,4'-dichlorobenzophenone with a purity of 99.46% and a yield of 92%.

[0089] Figure 1The 1H NMR spectrum of 4,4'-dichlorobenzophenone in Example 1a of the present invention; Figure 2 This is the 13C NMR spectrum of 4,4'-dichlorobenzophenone in Example 1a of the present invention. From... Figure 1 and Figure 2 It can be seen that the present invention has prepared 4,4'-dichlorobenzophenone.

[0090] The preparation methods of 4,4'-dichlorobenzophenone in Examples 2a-21a are basically the same as those in Example 1a, except that some parameters change during the preparation process. The specific changes are shown in Table 1.

[0091] Table 1

[0092]

[0093]

[0094] Example 1b

[0095] The preparation method of 4,4'-difluorobenzophenone in this embodiment includes the following steps:

[0096] 1) Preparation of tetramethylammonium fluoride as a fluorinating agent

[0097] Potassium fluoride and tetramethylammonium chloride were added to 300 ml of methanol at a molar ratio of 1:1 and refluxed at 80 °C for 2 h. After filtration, concentration and vacuum drying, a white solid tetramethylammonium fluoride was obtained with a yield of 88%.

[0098] 2) Preparation of 4,4'-difluorobenzophenone

[0099] The 4,4'-dichlorobenzophenone prepared in Example 1a and the tetramethylammonium fluoride prepared in step 1) were added to 200 ml of anhydrous dimethyl sulfoxide at a molar ratio of 1:3.5. The mixture was reacted at 180 °C for 9 h. The reaction yield was calculated to be 96% by GC detection of the sample.

[0100] After the reaction was completed, tetramethylammonium fluoride and tetramethylammonium chloride were washed with water, and the washings were extracted with dichloromethane 2-3 times. The organic phases were combined, dried with anhydrous sodium sulfate, concentrated, recrystallized with ethanol, washed, and dried to obtain 4,4'-difluorobenzophenone with a purity >99.5% and a yield of 92%. The tetramethylammonium fluoride and tetramethylammonium chloride in the aqueous phase were recovered and reused after concentration and drying.

[0101] Figure 3 The 1H NMR spectrum of 4,4'-difluorobenzophenone in Example 1b of the present invention; Figure 4 This is the 13C NMR spectrum of 4,4'-difluorobenzophenone in Example 1b of the present invention. From... Figure 3 and Figure 4 It can be seen that the present invention has prepared 4,4'-difluorobenzophenone.

[0102] The preparation methods of 4,4'-difluorobenzophenone provided in Examples 2b-9b are basically the same as those in Example 1b, except that some parameters change during the preparation process. The specific changes are shown in Table 2.

[0103] Table 2

[0104]

[0105]

[0106]

[0107] Comparative Example 1a

[0108] The preparation method of 4,4'-dichlorobenzophenone in this comparative example includes the following steps:

[0109] 1.5 mol of chlorobenzene and 1 mol of p-chlorobenzoyl chloride were added sequentially to a reaction flask, and the mixture was stirred at 25 °C for 90 min. GC analysis of the sample showed no product was detected.

[0110] Comparative Example 2a

[0111] The preparation method of 4,4'-dichlorobenzophenone in this comparative example includes the following steps:

[0112] 1.5 mol of chlorobenzene and 1.1 mol of anhydrous aluminum chloride were added sequentially to a reaction flask. Then, 1 mol of p-chlorobenzoyl chloride was added dropwise while stirring at 25°C for 30–40 minutes. After the addition was complete, the reaction was continued at 45°C for 2 hours. GC analysis of the sample showed a yield of 76%.

[0113] As can be seen from Examples 1a-21a and Comparative Examples 1a-2a, the present invention uses activated α-Fe2O3 instead of the traditional catalyst AlCl3, resulting in milder reaction conditions, higher selectivity, shorter reaction time, simpler separation, no large amount of wastewater generated, and the catalyst can be recycled. After multiple cycles, the reaction yield can be increased by adding a small amount of catalyst.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; 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 or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing 4,4'-dichlorobenzophenone, characterized in that, include: Under the action of activated α-Fe2O3, p-chlorobenzoyl chloride and chlorobenzene undergo an acylation reaction to give 4,4'-dichlorobenzophenone.

2. The method for preparing 4,4'-dichlorobenzophenone according to claim 1, characterized in that, In the acylation reaction, the temperature is 20-100℃ and the time is 0.5-4h; and / or, The molar ratio of p-chlorobenzoyl chloride to chlorobenzene is not higher than 1:1.1; and / or, The molar ratio of p-chlorobenzoyl chloride to the activated α-Fe2O3 is not higher than 1:0.

01.

3. The method for preparing 4,4'-dichlorobenzophenone according to any one of claims 1-2, characterized in that, The acylation reaction is followed by a post-treatment process, which includes: Add a non-aqueous solvent to the solution after the acylation reaction to obtain the first system; The first system was filtered to obtain recovered α-Fe2O3 and an organic phase. The organic phase was washed with an acid-base regulator and then concentrated, recrystallized, and dried sequentially to obtain the 4,4'-dichlorobenzophenone. The recovered α-Fe2O3 is returned to participate in the acylation reaction.

4. The method for preparing 4,4'-dichlorobenzophenone according to any one of claims 1-3, characterized in that, The non-water-soluble solvent includes at least one of dichloromethane, dichloroethane, ethyl acetate, toluene, and chlorobenzene; And / or, The acid-base regulator includes at least one of sodium bicarbonate, sodium carbonate, ammonium bicarbonate, sodium hydroxide, and potassium hydroxide solution.

5. A method for preparing 4,4'-difluorobenzophenone, characterized in that, include: Fluorination of 4,4'-dichlorobenzophenone yields 4,4'-difluorobenzophenone; The 4,4'-dichlorobenzophenone was prepared by the method for preparing 4,4'-dichlorobenzophenone according to any one of claims 1-4.

6. The method for preparing 4,4'-difluorobenzophenone according to claim 5, characterized in that, The 4,4'-difluorobenzophenone was obtained by fluorination with a fluorinating agent. The fluorinating agent is obtained by reacting a fluorine source with R4YCl; The fluorine source is selected from at least one of potassium fluoride, hydrogen fluoride, triethylamine hydrofluoride, and pyridine hydrofluoride; and / or, In R4YCl, R is selected from at least one of methyl, ethyl, propyl, butyl, phenyl, and benzyl, and Y is N or P.

7. The method for preparing 4,4'-difluorobenzophenone according to claim 6, characterized in that, The R4YCl is selected from at least one of tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetraphenylammonium chloride, tetramethylphosphine chloride, tetraethylphosphine chloride, tetrapropylphosphine chloride, tetrabutylphosphine chloride, and tetraphenylphosphine chloride.

8. The method for preparing 4,4'-difluorobenzophenone according to any one of claims 6 or 7, characterized in that, The molar ratio of Cl atoms in R4YCl to F atoms in the fluorine source is not higher than 1:1; and / or, In the fluorination treatment, the reaction temperature is 150-250℃ and the reaction time is 5-12h.

9. The method for preparing 4,4'-difluorobenzophenone according to any one of claims 5-8, characterized in that, The molar ratio of 4,4'-dichlorobenzophenone to the fluorinating agent is not higher than 1:

2.

10. A method for preparing polyetheretherketone, characterized in that, The polyetheretherketone was prepared from 4,4'-difluorobenzophenone; The 4,4'-difluorobenzophenone was prepared by the method for preparing 4,4'-difluorobenzophenone according to any one of claims 5-9.

Images