A palladium catalyst and its preparation method and application, and a method for synthesizing p-vinylbenzoic acid

Abstract

The invention discloses a palladium catalyst, a preparation method and application thereof, and a method for synthesizing p-vinylbenzoic acid. The palladium catalyst is [bis(4-(trifluoromethyl)phenyl)phosphinate ferrocene] palladium dichloride. The preparation method is as follows: the ligand ferrocene bis(4-(trifluoromethyl)phenyl)phosphinate and palladium dichloride are added to THF, heated to 60-80°C and stirred to dissolve, and the palladium catalyst is obtained by heat preservation reaction for 6-10 hours. With p-halogenated benzoic acid and vinylsilane compounds as raw materials, p-vinylbenzoic acid is synthesized by Hiyama cross-coupling reaction under the action of the above-mentioned palladium catalyst. The palladium catalyst is used to synthesize p-vinylbenzoic acid, has high chemical selectivity, high yield, high product quality, simple and efficient separation and purification method, mild reaction conditions, simple process and equipment, and provides a new synthesis method for p-vinylbenzoic acid and similar compounds.

Description

Technical Field

[0001] The invention relates to the field of fine organic synthesis, and in particular to a palladium catalyst and a preparation method and application thereof, and a synthesis method of p-vinylbenzoic acid. Background Art

[0002] p-Vinylbenzoic acid is an important organic intermediate and functional material in the field of organic synthesis, material chemistry and biomedical research. In the field of organic synthesis, it can be widely used in organic synthesis intermediates and metal organic monolithic materials; in the field of material chemistry, it can be used in nanocomposites, new water-soluble materials in the medical field; graphite electrode materials, organic luminescent materials, chromatographic column filling materials; in medicine and biology, it can be used in tumor suppressor biological agents and new tyrosinase inhibitors.

[0003] The synthesis methods of p-vinylbenzoic acid can be divided into the following three categories:

[0004] (1) In 2007, Sheng Wang et al. reported that p-chloromethylbenzoic acid was used as a raw material to react with triphenylphosphine to prepare p-chlorobenzoic acid phosphonium salt intermediate, which was then reacted with formaldehyde under alkaline conditions to undergo Wittig reaction to synthesize p-vinylbenzoic acid. The synthesis reaction formula is as follows:

[0005]

[0006] The synthesis method uses a large amount of formaldehyde and sodium hydroxide as raw materials, generates a large amount of waste water, has a long reaction process, has poor product quality, and has a reaction yield of only 59%.

[0007] (2) In 2008, Takeshi Ohishi et al. reported that p-vinylbenzoic acid was prepared by carboxylation reaction of 5,5-dimethyl-2-(4-vinylphenyl)-1,3,2-dioxaborinane with carbon dioxide in the presence of chloro[1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]copper(I)[(IPr)-CuCl]. The synthesis reaction is as follows:

[0008]

[0009] The raw material 5,5-dimethyl-2-(4-vinylphenyl)-1,3,2-dioxaborinane used in this method is not easy to obtain, the catalyst is difficult to prepare, and the reaction process requires high-pressure reaction conditions, which are harsh and not conducive to industrial production. The reaction process is only suitable for laboratory theoretical research.

[0010] (3) In 2011, Craig R. Smith et al. reported that p-vinylbenzoic acid was prepared by Heck-Mizoroki reaction of p-iodobenzoic acid with ethylene in the presence of palladium (II) ring catalyst and free radical inhibitor phenothiazine. The synthesis reaction formula is as follows:

[0011]

[0012] The catalyst used in this method is not easy to prepare, the palladium-catalyzed coupling reaction requires high temperature and high pressure, harsh reaction conditions, complex operation, poor reaction safety, and is not conducive to safe production. This synthesis method is only suitable for laboratory theoretical research. Summary of the invention

[0013] In order to solve the above technical problems, the purpose of the present invention is to provide a palladium catalyst and its preparation method and application, and a method for synthesizing p-vinylbenzoic acid. The palladium catalyst is used to synthesize p-vinylbenzoic acid, has high chemical selectivity, high yield, high product quality, simple and efficient separation and purification method, mild reaction conditions, simple process and equipment, and provides a new synthesis method for p-vinylbenzoic acid and similar compounds.

[0014] The technical solution adopted by the present invention to solve the above technical problems is:

[0015] Provided is a palladium catalyst, wherein the palladium catalyst is [bis(4-(trifluoromethyl)phenyl)phosphinate ferrocene]palladium dichloride.

[0016] According to the above scheme, in the palladium catalyst, the molar ratio of the ligand ferrocene bis(4-(trifluoromethyl)phenyl)phosphite to palladium dichloride is 1:1 to 1.4.

[0017] Provided is a method for preparing the above palladium catalyst, comprising the following steps:

[0018] Add the ligand ferrocene bis(4-(trifluoromethyl)phenyl)phosphite and palladium dichloride into THF, heat to 60-80°C and stir to dissolve it, keep the temperature to react for 6-10 hours, and obtain the palladium catalyst [bis(4-(trifluoromethyl)phenyl)phosphite ferrocene]palladium dichloride.

[0019] Provided is an application of the palladium catalyst in the preparation of p-vinylbenzoic acid, specifically: p-halogenated benzoic acid and vinylsilane compounds are used as raw materials, and p-vinylbenzoic acid is synthesized through a Hiyama cross-coupling reaction under the action of a palladium catalyst.

[0020] Provided is a method for synthesizing p-vinylbenzoic acid by a one-pot process, comprising the following steps:

[0021] 1) adding the ligand ferrocene bis(4-(trifluoromethyl)phenyl)phosphite and palladium dichloride to THF, heating the reaction to prepare a palladium catalyst [bis(4-(trifluoromethyl)phenyl)phosphite ferrocene]palladium dichloride, and the obtained palladium catalyst is not separated and used for standby;

[0022] 2) directly mixing the reaction solution containing the palladium catalyst obtained in step 1) with p-halogenated benzoic acid and a vinyl silane compound, and synthesizing p-vinyl benzoic acid through a Hiyama cross-coupling reaction.

[0023] The one-pot method for synthesizing p-vinylbenzoic acid provided by the present invention comprises the following steps: firstly, a palladium catalyst is prepared by itself, which is directly used for catalyzing the Hiyama cross-coupling reaction of p-halogenated benzoic acid and vinyl silane without separation, and then p-vinylbenzoic acid is synthesized through oxidation addition, transmetallation, cis-trans isomerization and reduction elimination. The general formula of vinyl is shown in V, and the specific reaction formula is as follows:

[0024]

[0025] According to the above scheme, the general formula of the p-halogenated benzoic acid is shown as IV, wherein X is Cl, Br or I; the general formula of the vinyl silane compound is shown as V, wherein R is Me, OMe or OEt.

[0026] According to the above scheme, in step 1), the heating temperature is 60-80° C. and the reaction time is 6-10 h.

[0027] According to the above scheme, in step 2), the molar ratio of p-halogenated benzoic acid to vinyl silane compound is 1:(1.1-1.8); in terms of molar percentage, the amount of palladium dichloride used is 0.1-0.5% of the molar amount of the p-halogenated benzoic acid raw material.

[0028] According to the above scheme, in step 2), the reaction conditions are: reaction temperature is 40-100° C., and reaction time is 4-8 h.

[0029] According to the above scheme, in the step 2), the synthesized p-vinylbenzoic acid is purified, and the specific steps are: cooling the reaction solution to 0°C and filtering; washing the filter cake with liquid alkali and deionized water respectively, and recovering the palladium catalyst; wherein the obtained alkali washing mother liquor is extracted with toluene, separated, and then concentrated hydrochloric acid is added to precipitate solids to obtain crude vinylbenzoic acid and dry it; the crude p-vinylbenzoic acid is dissolved by heating and refluxing with an alcohol aqueous solution, cooling to precipitate crystals, and filtering to obtain pure p-vinylbenzoic acid, wherein the mass ratio of the alcohol aqueous solution to the crude p-vinylbenzoic acid to be treated is (3-4):1.

[0030] Preferably, the alcohol aqueous solution is one of a methanol aqueous solution, an ethanol aqueous solution, a n-butanol aqueous solution, and an isopropanol aqueous solution.

[0031] The beneficial effects of the present invention are as follows:

[0032] 1. The present invention provides a self-made palladium catalyst, the ligand of which is ferrocene bis(4-(trifluoromethyl)phenyl)phosphite, which has high chemical selectivity, fast reaction rate, simple preparation method, no need to add additional activator in the hiyama cross-coupling reaction, and has no effect on product quality.

[0033] 2. The present invention provides a method for synthesizing p-vinylbenzoic acid by a one-pot process. First, a palladium catalyst is prepared by itself, and the catalyst is directly used for catalyzing the Hiyama cross-coupling reaction of p-halogenated benzoic acid and vinyl silane without separation to obtain p-vinylbenzoic acid. The method has a short synthesis route and can prepare the product in one step. The reaction catalyst has high chemical selectivity, a high pilot yield, high product quality, and a simple and efficient separation and purification method. The method does not require anhydrous and oxygen-free conditions, but is a conventional reaction condition. The reaction process is safe, the raw materials are cheap and readily available, and the method can be applied to large-scale industrial production. Meanwhile, the reaction process method has less three wastes, the reaction catalyst prepared by itself can be recycled, and the reaction is green and environmentally friendly. The reaction solvent and the recrystallization solvent can be recycled without affecting the product yield and purity. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with examples. Of course, the following examples should not be construed as limiting the present invention.

[0035] Each embodiment of the present invention is tested by this liquid chromatography (HPLC): chromatographic column (Eclipse XDB-C18, 5μm, 4.6*150mm), flow rate (1.2mL / min), wavelength (254nm), column temperature (25°C), elution time (20min), mobile phase: acetonitrile and 0.01% phosphate buffer.

[0036] Example 1

[0037] Provided is a method for preparing a palladium catalyst, comprising the following steps:

[0038] Into a 500mL four-necked reaction flask equipped with a stirring device, a thermometer, and a condenser, the ligand ferrocene bis(4-(trifluoromethyl)phenyl)phosphite (42.01g, 0.047mol), palladium dichloride (8.33g, 0.047mol), and 200gTHF were added and heated to 80°C and stirred to dissolve. The mixture was reacted at this temperature for 6h, and 44.98g of the homemade palladium catalyst [bis(4-(trifluoromethyl)phenyl)phosphite ferrocene]palladium dichloride was separated with a yield of 90%.

[0039] Example 2

[0040] A method for synthesizing p-vinylbenzoic acid is provided, comprising the following steps:

[0041] 1) Preparation of palladium catalyst: The preparation process is the same as in Example 1, except that the obtained catalyst is not separated.

[0042] 2) Synthesis of p-vinylbenzoic acid: p-Chlorobenzoic acid (6.58 kg, 42.00 mol), trimethylvinylsilane (4.63 kg, 46.20 mol) and THF (30.00 kg) were added to a 50 L enamel reactor equipped with a stirrer and a thermometer. The reaction solution containing the homemade palladium catalyst obtained in step 1) was heated to 60° C. and reacted for 6 hours. The reaction liquid was cooled to 0°C, filtered, the filter cake was washed with liquid alkali (4.76kg), filtered, and the filter cake was rinsed with deionized water (250.00g). The filter cake was palladium catalyst, which was vacuum dried at 80°C to obtain 43.18g of palladium catalyst, which can be recycled; the mother liquor was washed with alkali, extracted with toluene (30.00kg), separated, and then concentrated hydrochloric acid (7.00kg) was added to precipitate solids to obtain crude vinyl benzoic acid, which was dried to obtain 5.56kg of crude product, which was dissolved by heating to 60°C with methanol aqueous solution (methanol: water = 4:1, 22.24kg), cooled to 0°C, crystals were precipitated, filtered, and dried to obtain 5.07kg of white powder solid product, with a total yield of 81.5% and a content of 99.20% (HPLC). Melting point (DSC): 144.0-147.4°C. 1 H NMR (CDCl 3 , 400MHZ)δ: 1 H NMR (400 MHz, DMSO-d 6 )δ(ppm):12.91(s,1H,-COOH),7.92-7.89(d,J=12.0Hz,2H,Ph-H),7.54-7.52(d,J=8.0Hz,2H,Ph-H),6 .79-6.72(q,J=12.0Hz,2H,Ph-CH=), 5.94-5.90(d,1H,J=16.0Hz,=CH), 5.37-5.34(d,J=16.0Hz,=CH).

[0043] Comparative Example 1

[0044] Into a 50L enamel reactor equipped with a stirrer and a thermometer, p-chlorobenzoic acid (6.58kg, 42.00mol), trimethylvinylsilane (4.63kg, 46.20mol), DMF (30.00kg), an activator sodium fluoride (0.88kg, 21.00mol), and a palladium acetate catalyst (0.042mol, 9.43g) were added, and the mixture was heated to 120°C for 8 hours. The reaction liquid was cooled to 0°C, filtered, the filter cake was washed with liquid alkali (4.76 kg), filtered, and the filter cake was rinsed with deionized water (250.00 g). The filter cake was palladium acetate catalyst, which was vacuum dried at 80°C to obtain 8.96 g of palladium acetate catalyst, which can be recycled; the mother liquor was washed with alkali, extracted with toluene (30.00 kg), separated, and then concentrated hydrochloric acid (7.00 kg) was added to precipitate solids to obtain crude vinyl benzoic acid, which was dried to obtain 5.05 kg of crude product, which was dissolved by heating to 60°C with methanol aqueous solution (methanol: water = 4:1, 20.20 kg), cooled to 0°C, crystals were precipitated, filtered, and dried to obtain 4.42 kg of white powder solid product, with a total yield of 71.0% and a content of 98.51% (HPLC). Melting point (DSC): 143.6-148.1°C.

[0045] Comparative Example 2

[0046] Into a 50L enamel reactor equipped with a stirrer and a thermometer, p-chlorobenzoic acid (6.58kg, 42.00mol), trimethylvinylsilane (4.63kg, 46.20mol), DMF (30.00kg), an activator sodium fluoride (0.88kg, 21.00mol), a bistriphenylphosphine palladium dichloride catalyst (0.042mol, 29.48g) were added, and the mixture was heated to 120°C for 8 hours. The reaction liquid was cooled to 0°C, filtered, the filter cake was washed with liquid alkali (4.76kg), filtered, and the filter cake was rinsed with deionized water (250.00g). The filter cake was a bistriphenylphosphine palladium dichloride catalyst. After vacuum drying at 80°C, 25.50g of bistriphenylphosphine palladium dichloride catalyst was obtained, which can be recycled; the mother liquor was washed with alkali, extracted with toluene (30.00kg), separated, and then concentrated hydrochloric acid (7.00kg) was added to precipitate solids to obtain a crude vinyl benzoic acid product, which was dried to obtain 5.25kg of crude product and dissolved with methanol aqueous solution (methanol: water = 4:1, 21.00kg), cooled to 0°C, crystals were precipitated, filtered, and dried to obtain 4.67kg of white powder solid product, with a total yield of 75.0% and a content of 98.91% (HPLC). Melting point (DSC): 143.9-148.1°C.

[0047] Comparative Example 3

[0048] To a 50L enamel reactor equipped with a stirrer and a thermometer, add p-chlorobenzoic acid (6.58kg, 42.00mol), trimethylvinylsilane (4.63kg, 46.20mol), DMF (30.00kg), and palladium acetate catalyst (0.042mol, 9.43g), and heat to 120°C for 8 hours. The reaction liquid was cooled to 0°C, filtered, the filter cake was washed with liquid alkali (4.76kg), filtered, and the filter cake was rinsed with deionized water (250.00g). The filter cake was palladium acetate catalyst, which was vacuum dried at 80°C to obtain 9.05g of palladium acetate catalyst, which can be recycled; the mother liquor was washed with alkali, extracted with toluene (30.00kg), separated, and then concentrated hydrochloric acid (7.00kg) was added to precipitate solids to obtain crude vinyl benzoic acid, which was dried to obtain 4.59kg of crude product, which was dissolved by heating to 60°C with methanol aqueous solution (ethanol: water = 4:1, 18.36kg), cooled to 0°C, precipitated crystals, filtered, and dried to obtain 4.00kg of white powder solid product, with a total yield of 64.5% and a content of 97.70% (HPLC). Melting point (DSC): 142.1-148.5°C.

[0049] Example 3

[0050] A method for synthesizing p-vinylbenzoic acid is provided, comprising the following steps:

[0051] 1) Preparation of palladium catalyst: The preparation process is the same as in Example 1, except that the obtained catalyst is not separated.

[0052] 2) Synthesis of p-vinylbenzoic acid: p-Bromobenzoic acid (8.44 kg, 42.00 mol), trimethylvinylsilane (4.63 kg, 46.20 mol) and tetrahydrofuran (30.00 kg) were added to a 50 L enamel reactor equipped with a stirrer and a thermometer. The reaction solution containing the homemade palladium catalyst obtained in step 1) was heated to 70° C. and reacted for 6 hours. The reaction liquid was cooled to 0°C, filtered, the filter cake was washed with liquid alkali (4.76kg), filtered, and the filter cake was rinsed with deionized water (250.00g). The filter cake was palladium catalyst, which was vacuum dried at 80°C to obtain 44.20g of palladium catalyst, which can be recycled; the mother liquor was washed with alkali, extracted with toluene (30.00kg), separated, and then concentrated hydrochloric acid (7.00kg) was added to precipitate solids to obtain crude vinyl benzoic acid, which was dried to obtain 5.80kg of crude product, which was dissolved by heating to 60°C with methanol aqueous solution (methanol: water = 4:1, 23.20kg), cooled to 0°C, precipitated crystals, filtered, and dried to obtain 5.17kg of white powder solid product, with a total yield of 83.1% and a content of 99.50% (HPLC). Melting point (DSC): 144.3-147.0°C.

[0053] Example 4

[0054] A method for synthesizing p-vinylbenzoic acid is provided, comprising the following steps:

[0055] 1) Preparation of palladium catalyst: The preparation process is the same as in Example 1, except that the obtained catalyst is not separated.

[0056] 2) Synthesis of p-vinylbenzoic acid: p-Chlorobenzoic acid (6.58 kg, 42.00 mol) and trimethylvinylsilane (6.31 kg, 63.00 mol) and DMF (30.00 kg) were added to a 50 L enamel reactor equipped with a stirrer and a thermometer. The reaction solution containing the homemade palladium catalyst obtained in step 1) was heated to 80° C. and reacted for 4 hours. Filter, wash the filter cake with liquid alkali (4.76kg), filter, add deionized water (250.00g) to rinse the filter cake, the filter cake is palladium catalyst, after vacuum drying at 80℃, 44.05g of palladium catalyst is obtained, which can be recycled; wash the mother liquor with alkali, extract with toluene (30kg), separate the liquids, add concentrated hydrochloric acid (7kg), precipitate solids, obtain crude vinyl benzoic acid, dry, obtain 5.70kg crude product, heat to 60℃ and dissolve with methanol aqueous solution (methanol: water = 4:1, 22.80kg), cool to 0℃, precipitate crystals, filter, dry, obtain 5.41kg white powder solid product, total yield 87.0%, content 99.95% (HPLC). 144.6-146.0℃.

[0057] Example 5

[0058] A method for synthesizing p-vinylbenzoic acid is provided, comprising the following steps:

[0059] 1) Preparation of palladium catalyst: The preparation process is the same as in Example 1, except that the obtained catalyst is not separated.

[0060] 2) Synthesis of p-vinylbenzoic acid: p-Chlorobenzoic acid (6.58 kg, 42.00 mol), trimethoxyvinylsilane (6.85 kg, 46.20 mol) and acetonitrile (30.00 kg) were added to a 50 L enamel reactor equipped with a stirrer and a thermometer. The reaction solution containing the homemade palladium catalyst obtained in step 1) was heated to 80° C. and reacted for 6 hours. Filter, wash the filter cake with liquid alkali (4.76kg), filter, add deionized water (250.00g) to rinse the filter cake, the filter cake is palladium catalyst, after vacuum drying at 80℃, 43.85g of palladium catalyst is obtained, the mother liquor is washed with alkali, extracted with toluene (30.00kg), separated, and then concentrated hydrochloric acid (7.00kg) is added to precipitate solids to obtain crude vinyl benzoic acid, dry to obtain 5.73kg crude product and isopropanol aqueous solution (isopropanol: water = 4:1, 23.20kg) heated to 60℃ to dissolve, cooled to 0℃, precipitated crystals, filtered, dried to obtain 5.12kg white powder solid product, total yield 82.3%, content 99.90% (HPLC). Melting point (DSC): 144.1-147.0℃.

[0061] Example 6

[0062] A method for synthesizing p-vinylbenzoic acid is provided, comprising the following steps:

[0063] 1) Preparation of palladium catalyst: The preparation process is the same as in Example 1, except that the obtained catalyst is not separated.

[0064] 2) Synthesis of p-vinylbenzoic acid: p-Chlorobenzoic acid (6.58 kg, 42.00 mol) and trimethylvinylsilane (4.63 kg, 46.20 mol) and DMF (30.00 kg) were added to a 50 L enamel reactor equipped with a stirrer and a thermometer. The reaction solution containing the homemade palladium catalyst obtained in step 1) was heated to 100 ° C and reacted for 6 hours. The reaction liquid was cooled to 0°C, filtered, the filter cake was washed with liquid alkali (4.76 kg), filtered, and the filter cake was rinsed with deionized water (250.00 g). The filter cake was palladium catalyst, and 43.20 g of palladium catalyst was obtained after vacuum drying at 80°C, which can be recycled; the mother liquor was washed with alkali, extracted with toluene (30.00 kg), separated, and then concentrated hydrochloric acid (7.00 kg) was added to precipitate solids to obtain crude vinyl benzoic acid, dried to obtain 5.76 kg of crude product, heated to 60°C to dissolve with methanol aqueous solution (methanol: water = 4:1, 23.04 kg), cooled to 0°C, precipitated crystals, filtered, and dried to obtain 5.35 kg of white powder solid product, with a total yield of 86.0% and a content of 99.89% (HPLC). Melting point (DSC): 144.3-146.4°C.

[0065] Example 7

[0066] A method for synthesizing p-vinylbenzoic acid is provided, comprising the following steps:

[0067] 1) Preparation of palladium catalyst: The preparation process is the same as in Example 1, except that the amounts of the raw material ligand ferrocene bis(4-(trifluoromethyl)phenyl)phosphite, palladium dichloride and THF are doubled, and the prepared catalyst is not separated.

[0068] 2) Synthesis of p-vinylbenzoic acid: p-Chlorobenzoic acid (6.58 kg, 42.00 mol), trimethylvinylsilane (4.63 kg, 46.20 mol) and THF (30.00 kg) were added to a 50 L enamel reactor equipped with a stirrer and a thermometer. The reaction solution containing the homemade palladium catalyst obtained in step 1) was heated to 60° C. and reacted for 6 hours. The reaction liquid was cooled to 0°C, filtered, the filter cake was washed with liquid alkali (4.76kg), filtered, and the filter cake was rinsed with deionized water (250.00g). The filter cake was palladium catalyst, which was vacuum dried at 80°C to obtain 86.60g of palladium catalyst, which can be recycled; the mother liquor was washed with alkali, extracted with toluene (30.00kg), separated, and then concentrated hydrochloric acid (7.00kg) was added to precipitate solids to obtain crude vinyl benzoic acid, which was dried to obtain 5.79kg of crude product, which was dissolved by heating to 60°C with methanol aqueous solution (methanol: water = 4:1, 23.10kg), cooled to 0°C, crystals were precipitated, filtered, and dried to obtain 5.38kg of white powder solid product, with a total yield of 86.5% and a content of 99.95% (HPLC). Melting point (DSC): 144.5-146.4°C.

[0069] The present invention is described in detail through specific examples in the specification, but those skilled in the art may make various modifications and changes to the present invention within the scope and technical concept of the present invention, and these modifications and changes also fall within the scope of the claims of the present invention.

Claims

1. Use of [bis(4-(trifluoromethyl)phenyl)phosphinate ferrocene]palladium dichloride as a palladium catalyst in the preparation of p-vinylbenzoic acid, characterized in that: p-Vinylbenzoic acid was synthesized from p-halogenated benzoic acid and vinylsilane compounds via Hiyama cross-coupling reaction in the presence of [bis(4-(trifluoromethyl)phenyl)phosphinate ferrocene]palladium dichloride.

2. The use according to claim 1, characterized in that: The molar ratio of the ligand ferrocene bis(4-(trifluoromethyl)phenyl)phosphite to palladium dichloride is 1:1-1.

4.

3. The use according to claim 1, characterized in that: The preparation method of [bis(4-(trifluoromethyl)phenyl)phosphite ferrocene]palladium dichloride comprises the following steps: Add the ligand ferrocene bis(4-(trifluoromethyl)phenyl)phosphite and palladium dichloride into THF, heat to 60-80°C and stir to dissolve it, keep the temperature to react for 6-10 hours, and obtain [bis(4-(trifluoromethyl)phenyl)phosphite ferrocene]palladium dichloride.

4. A method for synthesizing p-vinylbenzoic acid by a one-pot process, characterized in that: The following steps are involved: 1) adding the ligand ferrocene bis(4-(trifluoromethyl)phenyl)phosphite and palladium dichloride to THF, heating the mixture for reaction to prepare a palladium catalyst [bis(4-(trifluoromethyl)phenyl)phosphite ferrocene]palladium dichloride; 2) directly mixing the reaction solution containing the palladium catalyst obtained in step 1) with p-halogenated benzoic acid and a vinyl silane compound, and synthesizing p-vinyl benzoic acid through a Hiyama cross-coupling reaction.

5. The method according to claim 4, characterized in that The general formula of the p-halogenated benzoic acid is shown in IV, wherein X is Cl, Br or I; the general formula of the vinyl silane compound is shown in V, wherein R is Me, OMe or OEt; 6. The method according to claim 4, characterized in that In the step 1), the heating temperature is 60-80° C. and the reaction time is 6-10 hours.

7. The method according to claim 4, characterized in that In the step 2), the molar ratio of the p-halogenated benzoic acid to the vinyl silane compound is 1:(1.1-1.8); in terms of molar percentage, the amount of palladium dichloride used in the step 1) is 0.1-0.5% of the molar amount of the p-halogenated benzoic acid as the raw material.

8. The method according to claim 4, characterized in that In the step 2), the reaction conditions are: reaction temperature is 40-100° C., and reaction time is 4-8 hours.

9. The method according to claim 4, characterized in that In the step 2), the synthesized p-vinylbenzoic acid is purified, and the specific steps are: cooling the reaction solution to 0°C and filtering; washing the filter cake with liquid alkali and deionized water respectively, and recovering the palladium catalyst; wherein the obtained alkali washing mother liquor is extracted with toluene, separated, and then concentrated hydrochloric acid is added to precipitate solids to obtain crude vinylbenzoic acid, drying, heating and refluxing the crude p-vinylbenzoic acid with an alcohol aqueous solution to dissolve it, cooling to precipitate crystals, and filtering to obtain pure p-vinylbenzoic acid, wherein the mass ratio of the alcohol aqueous solution to the crude p-vinylbenzoic acid to be treated is (3-4):1.

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