Process for the preparation of 4,4'-difluorodiphenylmethane and its use

Abstract

The application provides a preparation method of 4,4'-difluorobenzyl and application thereof. The preparation method of 4,4'-difluorobenzyl comprises the following steps: A) pyridine hydrofluoric acid salt solution and 4,4'-diaminodiphenyl methane are subjected to a salification reaction to obtain a salification product; B) the salification product is subjected to a diazotization reaction with nitrite to obtain a diazonium salt; and C) the diazonium salt is subjected to a thermal decomposition reaction to obtain 4,4'-difluorobenzyl. In the preparation method, pyridine hydrofluoric acid solution is used to replace hydrogen fluoride, the raw material used is safer, almost no hydrogen fluoride is overflowed under heating conditions, the corrosion of the equipment is smaller, the stability of the diazonium salt obtained by reaction is excellent, the diazonium salt is not easy to decompose at room temperature, and the decomposition at high temperature basically does not release a large amount of heat, so that the explosion risk is greatly reduced.

Description

Technical Field

[0001] This invention relates to a method for preparing 4,4′-difluorodiphenylmethane 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, or phosgene-catalyzed acylation.

[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, this method or the resulting DFBP 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 severe 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′-diaminodiphenylmethane involves diazotizing 4,4′-diaminodiphenylmethane 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. Compared to the three methods mentioned above, while the diazotization oxidation method using 4,4′-diaminodiphenylmethane is simpler and produces fewer impurities, its diazonium salt decomposes easily at slightly above room temperature, and the intense exothermic reaction accelerates the decomposition rate. This exothermic reaction is difficult to control in large-scale production, posing an explosion hazard. Furthermore, the reaction uses large amounts of hydrogen fluoride, resulting in severe equipment corrosion and a harsh operating environment. Summary of the Invention

[0008] This invention provides a method for preparing 4,4′-difluorodiphenylmethane, which uses pyridine hydrofluoric acid solution instead of hydrogen fluoride. The raw materials used are safer, and there is almost no hydrogen fluoride leakage under heating conditions. It has less corrosiveness to equipment, and the diazonium salt obtained from the reaction has excellent stability. It is not easy to decompose at room temperature, and the decomposition at high temperature does not release a lot of heat, which greatly reduces the risk of explosion.

[0009] This invention provides a method for preparing 4,4′-difluorobenzophenone. 4,4′-difluorobenzophenone is prepared using 4,4′-difluorobenzomethane obtained by the above method. Therefore, this preparation method has the advantages of low cost, high yield, low risk, and low waste.

[0010] 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 friendliness, making it suitable for widespread application.

[0011] This invention provides a method for preparing 4,4′-difluorodiphenylmethane, comprising the following steps:

[0012] A) A pyridine hydrofluoric acid salt solution reacts with 4,4′-diaminodiphenylmethane to form a salt product;

[0013] B) The salt-forming product reacts with nitrite via a diazotization reaction to obtain a diazonium salt;

[0014] C) The diazonium salt undergoes a thermal decomposition reaction to yield 4,4′-difluorodiphenylmethane.

[0015] In the preparation method of 4,4′-difluorodiphenylmethane as described above, the pyridine hydrofluoric acid salt solution includes hydrogen fluoride, and the mass percentage of the hydrogen fluoride is 55-75%.

[0016] In the preparation method of 4,4′-difluorodiphenylmethane as described above, the molar ratio of hydrogen fluoride to 4,4′-difluorodiphenylmethane is (20-50):1;

[0017] The molar ratio of the nitrite to the 4,4′-difluorodiphenylmethane is (1.8-2.2):1.

[0018] The method for preparing 4,4′-difluorodiphenylmethane as described above further includes a first post-treatment after the thermal decomposition reaction, the first post-treatment comprising:

[0019] An organic extractant was added to the solution after the thermal decomposition reaction, and the organic phase and the aqueous phase were extracted.

[0020] The organic phase was purified to obtain the 4,4′-difluorodiphenylmethane.

[0021] In the preparation method of 4,4′-difluorodiphenylmethane as described above, the salt formation reaction is carried out at a temperature of 10-25°C for a time of 1-2 hours; and / or,

[0022] The diazotization reaction is carried out at a temperature of 20-30°C for 2-3 hours; and / or,

[0023] The temperature of the thermal decomposition reaction is 100-110℃; and / or,

[0024] The organic extractant includes at least one of dichloromethane, dichloroethane, ethyl acetate, petroleum ether, and chloroform.

[0025] The method for preparing 4,4′-difluorodiphenylmethane as described above further includes:

[0026] The aqueous phase is recovered to participate in the next salt-forming reaction; and / or,

[0027] Hydrogen fluoride is added to the aqueous phase to participate in the next salt formation reaction.

[0028] In another aspect, the present invention provides a method for preparing 4,4′-difluorobenzophenone, comprising:

[0029] 4,4′-difluorodiphenylmethane was dissolved in an organic solvent to obtain a 4,4′-difluorodiphenylmethane solution;

[0030] 4,4′-Difluorodiphenylmethane solution reacts with hydrogen peroxide in the presence of a catalyst to produce 4,4′-difluorodiphenyl ketone.

[0031] The 4,4′-difluorodiphenylmethane was prepared by the method described above.

[0032] In the method for preparing 4,4′-difluorobenzophenone as described above, the mass ratio of the catalyst to the 4,4′-difluorodiphenylmethane is greater than 0.1:1; and / or,

[0033] The hydrogen peroxide in the hydrogen peroxide solution has a hydrogen peroxide content of 30-80% by mass; and / or,

[0034] The molar ratio of hydrogen peroxide in the hydrogen peroxide solution to 4,4′-difluorodiphenylmethane is (2-10):1.

[0035] In the preparation method of 4,4′-difluorobenzophenone as described above, the organic solvent is selected from at least one of acetonitrile, ethanol, ethylene glycol, sulfolane, dimethyl sulfoxide, dimethyl sulfone, N,N′-dimethylacrylamide, and N-methylpyrrolidone.

[0036] The method for preparing 4,4′-difluorobenzophenone as described above further includes a second post-treatment after the oxidation reaction, the second post-treatment comprising:

[0037] The solution after the oxidation reaction is filtered to obtain an intermediate solution and the recovered catalyst;

[0038] The intermediate solution was subjected to separation, decolorization, recrystallization and drying processes in sequence to obtain the 4,4′-difluorobenzophenone.

[0039] The recovered catalyst is refluxed to the oxidation reaction.

[0040] The oxidation reaction in the method for preparing 4,4′-difluorobenzophenone as described above includes:

[0041] 1) Add a catalyst to the 4,4′-difluorodiphenylmethane solution and heat to 100-150℃;

[0042] 2) Add hydrogen peroxide dropwise and keep warm for no less than 2 hours to obtain the 4,4′-difluorobenzophenone.

[0043] In another aspect, the present invention provides a method for preparing polyetheretherketone, wherein the polyetheretherketone is prepared by 4,4′-difluorobenzophenone;

[0044] The 4,4′-difluorobenzophenone was prepared by the method described above.

[0045] The method for preparing 4,4′-difluorodiphenylmethane of the present invention uses pyridine hydrofluoric acid solution instead of hydrogen fluoride for the diazotization reaction. This method uses safer raw materials, produces almost no hydrogen fluoride leakage under heating conditions, has less corrosiveness to equipment, and yields a diazonium salt with excellent stability. It does not easily decompose at room temperature, and its decomposition at high temperatures produces virtually no exothermic reaction, greatly reducing the risk of explosion.

[0046] This invention provides a method for preparing 4,4′-difluorobenzophenone. 4,4′-difluorobenzophenone is prepared using 4,4′-difluorobenzomethane obtained by the above method. Therefore, this preparation method has the advantages of low cost, high yield, low risk, and low waste.

[0047] 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 friendliness, making it suitable for widespread application. Attached Figure Description

[0048] 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.

[0049] Figure 1 This is the GC spectrum of the organic phase during the preparation of 4,4′-difluorodiphenylmethane in Example 1 of the present invention;

[0050] Figure 2 This is the GC spectrum of the reaction solution during the preparation of 4,4′-difluorobenzophenone in Example 1 of the present invention;

[0051] Figure 3 The GC-MS spectrum of 4,4′-difluorobenzophenone obtained in Example 1 of this invention;

[0052] Figure 4 The NMR spectrum obtained in Example 1 of this invention is shown below.

[0053] Figure 5 The NMR C spectrum obtained in Example 1 of this invention;

[0054] Figure 6 This is the NMR F-spectrum obtained in Example 1 of the present invention. Detailed Implementation

[0055] 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.

[0056] A first aspect of the present invention provides a method for preparing 4,4′-difluorodiphenylmethane, comprising the following steps:

[0057] A) A pyridine hydrofluoric acid salt solution reacts with 4,4′-diaminodiphenylmethane to form a salt product;

[0058] B) The salt-forming product reacts with nitrite via a diazotization reaction to obtain a diazonium salt;

[0059] C) The diazonium salt undergoes thermal decomposition to yield 4,4′-difluorodiphenylmethane.

[0060] Specifically, in the salt formation reaction, the amino group of 4,4′-diaminodiphenylmethane reacts with hydrogen fluoride in pyridine hydrofluoric acid to obtain a salt formation product including pyridinium 4,4′-diaminodiphenylmethane hydrofluoric acid; subsequently, the salt formation product undergoes a diazotization reaction with nitrite to obtain a diazonium salt including 4,4′-diazofluorodiphenylmethane; the diazonium salt including 4,4′-diazofluorodiphenylmethane undergoes a thermal decomposition reaction to obtain 4,4′-difluorodiphenylmethane.

[0061] In this invention, pyridine hydrofluoric acid salt solution is prepared by adding hydrogen fluoride to pyridine at low temperature. Compared to the traditional method of preparing 4,4′-difluorodiphenylmethane using hydrogen fluoride solution, this invention utilizes pyridine hydrofluoric acid salt solution to prepare 4,4′-difluorodiphenylmethane. Due to the complexation between pyridine and hydrogen fluoride, hydrogen fluoride in the pyridine hydrofluoric acid salt solution is less likely to escape under heating conditions, reducing corrosion to equipment. Furthermore, the reaction conditions for salt formation and diazo reaction using pyridine hydrofluoric acid salt solution are milder, resulting in excellent reaction safety. Simultaneously, the diazo salt prepared using pyridine hydrofluoric acid salt solution exhibits excellent stability, is not easily decomposed at room temperature, and decomposes at high temperatures with minimal exothermic reaction, significantly reducing the risk of explosion.

[0062] In some embodiments of the present invention, step A) further includes: stirring the pyridine hydrofluoric acid solution and cooling it to 5-10°C, then adding 4,4′-diaminodiphenylmethane, heating and stirring the reaction for 1 hour to obtain the salt-forming product.

[0063] Specifically, step A) further includes: stirring the pyridine hydrofluoric acid solution, and after the pyridine hydrofluoric acid solution is cooled to 5-10°C, adding 4,4′-diaminodiphenylmethane to the pyridine hydrofluoric acid solution. After the addition of 4,4′-diaminodiphenylmethane is completed, the temperature is raised to allow the pyridine hydrofluoric acid solution to undergo a salt formation reaction with 4,4′-diaminodiphenylmethane to obtain the salt formation product.

[0064] This invention uses pyridine hydrofluoric acid solution to participate in the salt formation reaction. The reaction temperature is lower, the reaction conditions are milder, and the safety is higher.

[0065] In some embodiments of the present invention, step B) includes: cooling the salt-forming product to 0-10°C, then adding nitrite, and heating to carry out a diazotization reaction to obtain a diazonium salt.

[0066] Specifically, step B) includes: cooling the salt-forming product to 0-10℃, then adding nitrite to the salt-forming product, followed by heating. During the heating process, the reaction solution changes from pale yellow to reddish-brown. The temperature is maintained so that the nitrite and the salt-forming product undergo a diazotization reaction for 2-3 hours to obtain a diazonium salt.

[0067] In some embodiments, nitrite can be added to the salt-forming product in batches. This process is slightly exothermic, and the reaction temperature is controlled within 0-10°C throughout the process.

[0068] This invention does not limit the specific type of nitrite. Appropriate types of nitrite can be selected according to actual conditions, such as sodium nitrite, potassium nitrite, magnesium nitrite, calcium nitrite, etc.

[0069] In the diazotization reaction of this invention, the reaction temperature is lower, the reaction conditions are milder, the safety is higher, and there are fewer side reactions. The obtained diazonium salt has excellent stability and is not easily decomposed at room temperature, which helps to improve the purity of the product.

[0070] Specifically, step C) includes: heating the diazonium salt until nitrogen gas is generated, then maintaining the temperature until no more gas is generated, to obtain 4,4′-difluorodiphenylmethane. In some embodiments, the thermal decomposition reaction can be carried out in a reactor, the temperature of which is adjusted by controlling the temperature of the reactor, and the presence or absence of gas generation during the thermal decomposition reaction can be determined based on the pressure of the reactor.

[0071] The thermal decomposition reaction of this invention generates virtually no heat, which reduces the risk of reaction explosion and improves the safety of the preparation method.

[0072] Furthermore, the pyridine hydrofluoric acid solution also contains hydrogen fluoride, with a mass percentage of 55-75% (the molar ratio of hydrofluoric acid to pyridine in the pyridine hydrofluoric acid solution is (4.83-11.85):1).

[0073] In this invention, pyridine hydrofluoric acid solutions with different hydrogen fluoride contents can be obtained by controlling the amount of hydrogen fluoride added to the pyridine hydrofluoric acid solution. Furthermore, the inventors discovered that the temperature required for hydrogen fluoride to escape from pyridine hydrofluoric acid solutions with different hydrogen fluoride contents also varies. Excessively high hydrogen fluoride concentrations result in excessively low hydrogen fluoride escape temperatures for pyridine hydrofluoric acid; conversely, excessively low hydrogen fluoride concentrations lead to weak acidity, which is detrimental to the diazotization reaction. When the mass percentage of hydrogen fluoride in a pyridine hydrofluoric acid solution is 70% (molar ratio of hydrogen fluoride to pyridine is 9.23:1), the boiling point of the pyridine hydrofluoric acid solution is around 55℃; when the mass percentage of hydrogen fluoride in a pyridine hydrofluoric acid solution is 60% (molar ratio of hydrogen fluoride to pyridine is 5.93:1), the boiling point of the pyridine hydrofluoric acid solution is around 90℃; when the mass percentage of hydrogen fluoride in a pyridine hydrofluoric acid solution is 57% (molar ratio of hydrogen fluoride to pyridine is 5.24:1), the boiling point of the pyridine hydrofluoric acid solution is above 150℃.

[0074] When the mass percentage of hydrogen fluoride in the pyridine hydrofluoric acid salt solution is 55-75%, the acidity of the pyridine hydrofluoric acid salt solution is sufficient to promote the diazotization reaction, and the high escape temperature of hydrogen fluoride helps to improve the safety of the reaction.

[0075] The inventors also discovered that when the molar ratio of hydrogen fluoride to 4,4′-diaminodiphenylmethane in the pyridine hydrofluoric acid solution is (20-50):1, and the molar ratio of nitrite to 4,4′-difluorodiphenylmethane is (1.8-2.2):1, the raw materials can react more fully, increasing the reaction rate and thus obtaining high-quality 4,4′-difluorodiphenylmethane.

[0076] In some embodiments of the present invention, a first post-processing is further included after the thermal decomposition reaction, the first post-processing including:

[0077] An organic extractant was added to the solution after the thermal decomposition reaction to extract an organic phase and an aqueous phase. The organic phase was then purified to obtain 4,4′-difluorodiphenylmethane.

[0078] In this invention, a solution containing 4,4′-difluorodiphenylmethane can be obtained after thermal decomposition. An organic extractant can be used to extract the solution containing 4,4′-difluorodiphenylmethane obtained after thermal decomposition. In this solution, 4,4′-difluorodiphenylmethane is located in the organic phase, and the pyridine hydrofluoric acid salt solution is located in the aqueous phase. After purifying the organic phase, pure 4,4′-difluorodiphenylmethane can be obtained. The aqueous phase containing the pyridine hydrofluoric acid salt solution can participate in the salt formation reaction again.

[0079] In this invention, purification can be performed using methods commonly used in the art, such as water washing, concentration, and distillation.

[0080] This invention uses an organic extractant to extract the solution after thermal decomposition reaction, which can obtain 4,4′-difluorodiphenylmethane with higher purity. Furthermore, the aqueous phase, including the pyridine hydrofluoric acid solution, can be recycled, thus improving the utilization rate of raw materials.

[0081] Furthermore, the temperature for the salt formation reaction is 10-25℃ and the time is 1-2h; the temperature for the diazotization reaction is 20-30℃ and the time is 2-3h; and the temperature for the thermal decomposition reaction is 100-110℃.

[0082] The temperature for the salt formation reaction includes, but is not limited to, 10℃, 12℃, 14℃, 16℃, 18℃, 20℃, 22℃, 24℃, 25℃, or any combination thereof, and the time includes, but is not limited to, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2.0h, or any combination thereof; the temperature for the diazotization reaction includes, but is not limited to, 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, or any combination thereof, and the time includes, but is not limited to, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3.0h, or any combination thereof; the temperature for the thermal decomposition reaction includes, but is not limited to, 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, or any combination thereof.

[0083] In some embodiments, the salt formation reaction and the diazotization reaction can be carried out in a reaction vessel, and the temperature of the salt formation reaction and the diazotization reaction can be controlled by heating or cooling the reaction vessel.

[0084] When the reaction temperature and time at each stage are within the above range, the various raw materials can react fully, thus improving the reaction efficiency.

[0085] Furthermore, the organic extractant includes at least one of dichloromethane, dichloroethane, ethyl acetate, petroleum ether, and chloroform.

[0086] The above-mentioned organic extractants can achieve full extraction of the organic and aqueous phases without introducing new impurities. They can also effectively separate the organic phase during purification, thereby improving the purity of 4,4′-difluorodiphenylmethane.

[0087] In some embodiments of the present invention, the method further includes: recovering the aqueous phase to participate in the next salt-forming reaction, and / or,

[0088] Add hydrogen fluoride to the aqueous phase to participate in the next salt formation reaction.

[0089] In practical applications, when using the recovered pyridine hydrofluoric acid solution to prepare 4,4′-difluorodiphenylmethane, if the yield decreases, hydrogen fluoride can be added directly to participate in the salt formation reaction to improve the yield of 4,4′-difluorodiphenylmethane.

[0090] The amount of hydrogen fluoride added can be adjusted according to the yield. For example, if the yield is more than 5% lower than the previous yield, hydrogen fluoride needs to be added every time thereafter. The molar ratio of the added hydrogen fluoride to the previously added 4,4′-diaminodiphenylmethane is 2:1.

[0091] By separating, recycling, and reusing pyridine hydrofluoric acid solution, the utilization rate of raw materials can be improved and production costs reduced.

[0092] A second aspect of the present invention provides a method for preparing 4,4′-difluorobenzophenone, comprising: dissolving 4,4′-difluorobenzomethane in an organic solvent to obtain a 4,4′-difluorobenzomethane solution; reacting the 4,4′-difluorobenzomethane solution with hydrogen peroxide under the action of a catalyst to obtain 4,4′-difluorobenzophenone; wherein the 4,4′-difluorobenzomethane is prepared by the method for preparing 4,4′-difluorobenzomethane provided in the first aspect.

[0093] This invention does not impose any particular limitation on the catalyst; the catalyst can be any catalyst commonly used in the art. In some embodiments, the catalyst can be a titanium-silicon molecular sieve, and the titanium-silicon molecular sieve can be TS-1. Using titanium-silicon molecular sieves to catalyze oxidation reactions can increase the reaction rate of the oxidation reaction, and compared with alumina catalysts, titanium-silicon molecular sieves do not generate a large amount of aluminum-containing wastewater, thus improving environmental friendliness.

[0094] Specifically, as shown in Formula 1, 4,4′-difluorodiphenylmethane is prepared by the method of the first aspect and dissolved in a solvent to obtain a 4,4′-difluorodiphenylmethane solution; then the 4,4′-difluorodiphenylmethane solution is reacted with hydrogen peroxide under the action of a catalyst to obtain 4,4′-difluorodiphenyl ketone.

[0095]

[0096] In the preparation method of 4,4′-difluorobenzophenone of the present invention, hydrogen peroxide is used as an oxidant for the oxidation reaction, and the reaction product is only water, without generating waste acid or waste gas, thus exhibiting excellent environmental friendliness. Furthermore, since 4,4′-difluorobenzophenone is prepared from 4,4′-difluorodiphenylmethane obtained by the method of the first aspect, this preparation method has the advantages of low cost, high yield, low risk, and low waste.

[0097] Furthermore, when the mass ratio of the catalyst to 4,4′-difluorodiphenylmethane is greater than 0.1:1, the reaction efficiency of the oxidation reaction can be improved while saving catalyst.

[0098] Preferably, the mass ratio of the catalyst to 4,4′-difluorodiphenylmethane is (0.1-1):1. When the mass ratio of the catalyst to 4,4′-difluorodiphenylmethane meets the above range, it can ensure production efficiency, effectively control production costs, and reduce the difficulty of impurity removal.

[0099] When the mass percentage of H2O2 in hydrogen peroxide is 30-80%, hydrogen peroxide can react more fully with 4,4′-difluorodiphenylmethane, thus improving the reaction efficiency.

[0100] When the molar ratio of H2O2 in hydrogen peroxide to 4,4′-difluorodiphenylmethane is (2-10):1, the H2O2 and 4,4′-difluorodiphenylmethane can react more fully, thus improving the reaction efficiency.

[0101] The solvent of the present invention can be any solvent commonly used in the art that can dissolve 4,4′-difluorodiphenylmethane. In some embodiments, the yield of 4,4′-difluorodiphenylmethane can be further improved when the solvent is at least one of acetonitrile, ethanol, ethylene glycol, sulfolane, dimethyl sulfoxide, dimethyl sulfone, N,N′-dimethylacrylamide, and N-methylpyrrolidone.

[0102] Furthermore, the oxidation reaction is followed by a second post-treatment, which includes:

[0103] The solution after the oxidation reaction was filtered to obtain an intermediate solution and a recovered catalyst. The intermediate solution was then subjected to separation, decolorization, recrystallization, and drying to obtain 4,4′-difluorobenzophenone. The recovered catalyst was refluxed to the oxidation reaction.

[0104] After oxidation, a solution containing the catalyst and 4,4′-difluorobenzophenone is obtained. The solution containing the catalyst and 4,4′-difluorobenzophenone can be filtered to separate the catalyst, resulting in an intermediate solution containing 4,4′-difluorobenzophenone. Then, the intermediate solution containing 4,4′-difluorobenzophenone is subjected to separation, activated carbon decolorization, ethanol recrystallization, and drying to obtain 4,4′-difluorobenzophenone. The obtained catalyst can be returned to participate in the oxidation reaction.

[0105] In some embodiments, the catalyst can be washed with methanol after filtration, then steam purged, and hydrogen peroxide slowly added dropwise to the recovered catalyst in a regeneration reactor to oxidize and decompose the organic matter attached to the recovered catalyst and its pores. Finally, it is washed with a small amount of deionized water and dried to obtain the recovered catalyst.

[0106] This invention, by performing a second post-processing after the oxidation reaction, can obtain 4,4′-difluorobenzophenone with higher purity, and can also recycle and reuse the catalyst, thereby improving the utilization rate of raw materials.

[0107] Further, the oxidation reaction includes: adding a catalyst to a solution of 4,4′-difluorodiphenylmethane and heating to 100-150°C;

[0108] Add hydrogen peroxide dropwise and keep warm for at least 2 hours to obtain 4,4′-difluorobenzophenone.

[0109] Specifically, it also includes adding a catalyst to a 4,4′-difluorodiphenylmethane solution and heating it to 100-150°C;

[0110] Hydrogen peroxide was added dropwise to a solution of 4,4′-difluorodiphenylmethane containing a catalyst, and then the solution was kept at a temperature of not less than 2 hours to carry out an oxidation reaction to obtain 4,4′-difluorodiphenylmethane.

[0111] From the perspective of process and production efficiency, the optimal heat preservation time is 2-10 hours. When the heat preservation time exceeds 10 hours, the yield does not increase significantly.

[0112] In some implementations, the hydrogen peroxide dripping time is controlled to be 1-2 hours.

[0113] The present invention performs the oxidation reaction at the above temperature, which can increase the reaction rate while saving energy consumption.

[0114] A fourth aspect of the present invention provides a method for preparing polyetheretherketone, wherein the polyetheretherketone is prepared by 4,4′-difluorobenzophenone;

[0115] 4,4′-Difluorobenzophenone was prepared by the method for preparing 4,4′-difluorobenzophenone as described in the second aspect.

[0116] The present invention uses the method for preparing 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.

[0117] The present invention will now be described in detail through specific embodiments.

[0118] Example 1a

[0119] The preparation method of 4,4′-difluorodiphenylmethane in this embodiment includes the following steps:

[0120] Preparation of 4,4′-difluorodiphenylmethane

[0121] A pyridine hydrofluoric acid salt solution with a hydrogen fluoride mass percentage of 65% (100 mol of hydrogen fluoride) was added to a reaction vessel, and the temperature was lowered to 5°C with stirring. Then, 4,4′-diaminodiphenylmethane was added to the reaction vessel. After the addition of 4,4′-diaminodiphenylmethane was complete, the temperature was raised to 18°C ​​and the reaction was stirred for 1.5 h to obtain the salt-forming product, wherein the molar ratio of hydrogen fluoride to 4,4′-difluorodiphenylmethane was 35:1.

[0122] The temperature of the reactor was lowered to 0℃, and sodium nitrite was added to the reactor in batches. The temperature of the reaction solution was kept within 0 to 10℃ throughout the process. The temperature of the reactor was raised to 25℃ and kept at this temperature for 2.5 hours to carry out the diazotization reaction to obtain the diazonium salt. The molar ratio of sodium nitrite to 4,4′-difluorodiphenylmethane was 2.025:1.

[0123] Finally, the reactor was slowly heated. At 100°C, nitrogen gas was generated. The temperature was then increased by 5°C and the reaction was maintained until no more decomposition gas was generated, resulting in a solution containing 4,4′-difluorodiphenylmethane.

[0124] The solution (reaction solution) containing 4,4′-difluorodiphenylmethane was cooled to room temperature, and 5 kg of dichloromethane was added to the reaction solution for extraction, resulting in an organic phase containing 4,4′-difluorodiphenylmethane and an aqueous phase containing a pyridine hydrofluoric acid solution. The organic phase was washed with water, concentrated, and distilled to obtain 4,4′-difluorodiphenylmethane with a yield of 92%.

[0125] GC analysis was performed on the organic phase to obtain its GC spectrum. Figure 1 This is the GC spectrum of the organic phase during the preparation of 4,4′-difluorodiphenylmethane in Example 1a of the present invention. Figure 1 As can be seen, the GC peak area of ​​4,4′-difluorodiphenylmethane accounts for more than 95% in the organic phase, and the GC purity of the finally obtained 4,4′-difluorodiphenylmethane is 99%, as shown in Table 1.

[0126] The preparation methods of 4,4′-difluorodiphenylmethane provided in Examples 2a-35a are basically the same as those in Example 1a, with some parameters changing. The specific parameters are shown in Table 1.

[0127] Table 1

[0128]

[0129]

[0130]

[0131] Example 36a

[0132] The preparation method of 4,4′-difluorobenzophenone in this embodiment is basically the same as that in Example 1a, except that:

[0133] 1) Preparation of 4,4′-difluorodiphenylmethane

[0134] The pyridine hydrofluoric acid solution recovered in Example 1a was used to replace the pyridine hydrofluoric acid solution in Example 1a to obtain 4,4′-difluorodiphenylmethane with a yield of 93%, as shown in Table 2.

[0135] Example 37a

[0136] The preparation method of 4,4′-difluorobenzophenone in this embodiment is basically the same as that in Example 1a, except that:

[0137] 1) Preparation of 4,4′-difluorodiphenylmethane

[0138] Replacing the pyridine hydrofluoric acid solution in Example 1a with the pyridine hydrofluoric acid solution recovered in Example 36a yielded 4,4′-difluorodiphenylmethane in 90% yield.

[0139] Example 38a

[0140] The preparation method of 4,4′-difluorobenzophenone in this embodiment is basically the same as that in Example 1a, except that:

[0141] 1) Preparation of 4,4′-difluorodiphenylmethane

[0142] Replacing the pyridine hydrofluoric acid solution in Example 1a with the pyridine hydrofluoric acid solution recovered in Example 37a yielded 4,4′-difluorodiphenylmethane in 89% yield.

[0143] Example 39a

[0144] The preparation method of 4,4′-difluorobenzophenone in this embodiment is basically the same as that in Example 1a, except that:

[0145] 1) Preparation of 4,4′-difluorodiphenylmethane

[0146] Replacing the pyridine hydrofluoric acid solution in Example 1a with the pyridine hydrofluoric acid solution recovered in Example 38a yielded 4,4′-difluorodiphenylmethane in 84% yield.

[0147] Example 40a

[0148] The preparation method of 4,4′-difluorobenzophenone in this embodiment is basically the same as that in Example 1a, except that:

[0149] 1) Preparation of 4,4′-difluorodiphenylmethane

[0150] The pyridine hydrofluoric acid solution recovered in Example 30a was used to replace the pyridine hydrofluoric acid solution in Example 1a, and 480g of hydrogen fluoride was added to obtain 4,4′-difluorodiphenylmethane with a yield of 94%.

[0151] Example 41a

[0152] The preparation method of 4,4′-difluorobenzophenone in this embodiment is basically the same as that in Example 1a, except that:

[0153] 1) Preparation of 4,4′-difluorodiphenylmethane

[0154] The pyridine hydrofluoric acid solution recovered in Example 40a was used to replace the pyridine hydrofluoric acid solution in Example 1a, and 160g of hydrogen fluoride was added to obtain 4,4′-difluorodiphenylmethane with a yield of 91%.

[0155] Example 42a

[0156] The preparation method of 4,4′-difluorobenzophenone in this embodiment is basically the same as that in Example 1a, except that:

[0157] 1) Preparation of 4,4′-difluorodiphenylmethane

[0158] The pyridine hydrofluoric acid solution recovered in Example 44a was used to replace the pyridine hydrofluoric acid solution in Example 1a, and 160g of hydrogen fluoride was added to obtain 4,4′-difluorodiphenylmethane with a yield of 90%.

[0159] Example 43a

[0160] The preparation method of 4,4′-difluorobenzophenone in this embodiment is basically the same as that in Example 1a, except that:

[0161] 1) Preparation of 4,4′-difluorodiphenylmethane

[0162] The pyridine hydrofluoric acid solution recovered in Example 42a was used to replace the pyridine hydrofluoric acid solution in Example 1a, and 160g of hydrogen fluoride was added to obtain 4,4′-difluorodiphenylmethane with a yield of 92%.

[0163] Table 2

[0164]

[0165] As can be seen from Examples 1a and 36a to 43a, the recovered pyridine hydrofluoric acid solution can be recycled. After being recycled four times, the yield of 4,4′-difluorodiphenylmethane is still above 80%, and subsequent addition of hydrogen fluoride can increase the yield back to the initial level.

[0166] Example 1b

[0167] The preparation method of 4,4′-difluorobenzophenone provided in this embodiment includes the following steps:

[0168] 4,4′-difluorodiphenylmethane and titanium silicate molecular sieve TS-1 were added to 1L of acetonitrile. The reaction solution was heated to 125℃, and then 50wt% hydrogen peroxide was slowly added dropwise to the reaction solution over a period of 1 hour. After the addition was complete, the reaction was kept at the temperature and refluxed for 6 hours. GC results showed that the raw materials were completely oxidized, yielding a solution containing the catalyst and 4,4′-difluorodiphenylmethane.

[0169] The solution containing the catalyst and 4,4′-difluorobenzophenone was filtered to recover the titanium silicate molecular sieve TS-1 and obtain an intermediate solution.

[0170] The intermediate solution was extracted with dichloromethane, decolorized with activated carbon, concentrated, recrystallized with ethanol, and dried to obtain 4,4′-difluorobenzophenone.

[0171] The reaction solution after oxidation was subjected to GC testing to obtain the GC spectrum of the reaction solution. Figure 2 This is the GC spectrum of the reaction solution during the preparation of 4,4′-difluorobenzophenone in Example 1 of this invention. Figure 2 It can be calculated that the yield reaches 95%.

[0172] Figure 3 This is the GC-MS spectrum of 4,4′-difluorobenzophenone obtained in Example 1b of the present invention. Figure 3 It can be seen that the purity of the 4,4′-difluorobenzophenone obtained in this embodiment is >99.9%.

[0173] Figure 4 The NMR spectrum obtained in Example 1b of this invention is shown below. Figure 5 The NMR C spectrum obtained in Example 1b of this invention; Figure 6 This is the NMR F-spectrum obtained in Example 1b of the present invention. From... Figures 4-6 As can be seen, 4,4′-difluorobenzophenone was prepared in Example 1b of the present invention.

[0174] The 4,4′-difluorobenzophenone provided in Examples 2b-25b is basically the same as that in Example 1b, except that some parameters have changed. The specific parameters are shown in Table 3.

[0175] Table 3

[0176]

[0177]

[0178] Example 25b

[0179] The preparation method of 4,4′-difluorobenzophenone in this embodiment is basically the same as that in Example 1b, except that:

[0180] 2) Preparation of 4,4′-difluorobenzophenone

[0181] The TS-1 catalyst recovered in Example 1b was first washed with a small amount of methanol solvent, then purged with steam, and then 30 wt% H2O2 was slowly added dropwise in a regeneration reactor while stirring. Finally, it was washed with deionized water and dried to obtain the recovered catalyst.

[0182] The catalyst in Example 1b was replaced with a recycled catalyst, as detailed in Table 4.

[0183] Examples 26b-29b

[0184] The preparation methods of 4,4′-difluorobenzophenone in Examples 26b-29b are basically the same as those in Example 1, except that:

[0185] 2) Preparation of 4,4′-difluorobenzophenone

[0186] The catalyst in Example 1b was replaced with the catalyst recovered in the previous instance, as detailed in Table 4.

[0187] Table 4

[0188] Catalyst TS-1 reuse times 4,4′-Difluorodiphenylmethane yield / % Example 25b 1 93 Example 26b 2 91 Example 27b 3 90 Example 28b 4 88 Example 29b 5 86

[0189] As can be seen from Table 4, the catalyst titanium silicate molecular sieve TS-1 has good recycling and regeneration capabilities. After being reused 5 times, the product yield still remains above 85%.

[0190] 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'-difluorodiphenylmethane, characterized in that, Includes the following steps: A) A pyridine hydrofluoric acid solution reacts with 4,4'-diaminodiphenylmethane via a salt-forming reaction to yield the salt-forming product; B) The salt-forming product reacts with nitrite via a diazotization reaction to obtain a diazonium salt; C) The diazonium salt undergoes a thermal decomposition reaction to yield 4,4'-difluorodiphenylmethane.

2. The method for preparing 4,4'-difluorodiphenylmethane according to claim 1, characterized in that, The pyridine hydrofluoric acid solution includes hydrogen fluoride, and the mass percentage of the hydrogen fluoride is 55-75%.

3. The method for preparing 4,4'-difluorodiphenylmethane according to claim 1 or 2, characterized in that, The molar ratio of the hydrogen fluoride to the 4,4'-difluorodiphenylmethane is (20-50):1; The molar ratio of the nitrite to the 4,4'-difluorodiphenylmethane is (1.8-2.2):

1.

4. The method for preparing 4,4'-difluorodiphenylmethane according to any one of claims 1-3, characterized in that, The thermal decomposition reaction is followed by a first post-processing, which includes: An organic extractant was added to the solution after the thermal decomposition reaction, and the organic phase and the aqueous phase were extracted. The organic phase was purified to obtain the 4,4'-difluorodiphenylmethane.

5. The method for preparing 4,4'-difluorodiphenylmethane according to any one of claims 1-4, characterized in that, The salt-forming reaction is carried out at a temperature of 10-25℃ for a time of 1-2 hours; and / or, The diazotization reaction is carried out at a temperature of 20-30°C for 2-3 hours; and / or, The temperature of the thermal decomposition reaction is 100-110℃; and / or, The organic extractant includes at least one of dichloromethane, dichloroethane, ethyl acetate, petroleum ether, and chloroform.

6. The method for preparing 4,4'-difluorodiphenylmethane according to any one of claims 1-5, characterized in that, Also includes: The aqueous phase is recovered and used in the next salt-forming reaction; And / or, Hydrogen fluoride is added to the aqueous phase to participate in the next salt formation reaction.

7. A method for preparing 4,4'-difluorobenzophenone, characterized in that, include: 4,4'-difluorodiphenylmethane was dissolved in an organic solvent to obtain a 4,4'-difluorodiphenylmethane solution; 4,4'-Difluorodiphenylmethane solution reacts with hydrogen peroxide in the presence of a catalyst to produce 4,4'-difluorodiphenyl ketone. The 4,4'-difluorodiphenylmethane is prepared by the method for preparing 4,4'-difluorodiphenylmethane according to any one of claims 1-6.

8. The method for preparing 4,4'-difluorobenzophenone according to claim 7, characterized in that, The mass ratio of the catalyst to the 4,4'-difluorodiphenylmethane is greater than 0.1:1; and / or, The hydrogen peroxide in the hydrogen peroxide solution has a hydrogen peroxide content of 30-80% by mass; and / or, The molar ratio of hydrogen peroxide in the hydrogen peroxide solution to 4,4'-difluorodiphenylmethane is (2-10):

1.

9. The method for preparing 4,4'-difluorobenzophenone according to claim 7, characterized in that, The organic solvent is selected from at least one of acetonitrile, ethanol, ethylene glycol, sulfolane, dimethyl sulfoxide, dimethyl sulfone, N,N'-dimethylacrylamide, and N-methylpyrrolidone.

10. The method for preparing 4,4'-difluorobenzophenone according to any one of claims 7-9, characterized in that, The oxidation reaction is followed by a second post-processing, which includes: The solution after the oxidation reaction is filtered to obtain an intermediate solution and the recovered catalyst; The intermediate solution was subjected to separation, decolorization, recrystallization and drying processes in sequence to obtain the 4,4'-difluorobenzophenone. The recovered catalyst is refluxed to the oxidation reaction.

11. The method for preparing 4,4'-difluorobenzophenone according to any one of claims 7-10, characterized in that, The oxidation reaction includes: 1) Add a catalyst to the 4,4'-difluorodiphenylmethane solution and heat to 100-150℃; 2) Add hydrogen peroxide dropwise and keep warm for no less than 2 hours to obtain the 4,4'-difluorobenzophenone.

12. 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 7-11.

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