Application of silver-palladium-based catalyst in photo-induced C-C coupling reaction and method thereof

Abstract

The application belongs to the technical field of C-C bond construction, and provides application of a silver-palladium-based catalyst in a photo-induced C-C coupling reaction and a method for the application. The method comprises the following steps: under a protective atmosphere, mixing a halogenated aromatic hydrocarbon, a phenylboronic acid substance, potassium carbonate, the silver-palladium-based catalyst and a solvent, and performing a photo-induced C-C coupling reaction to obtain a product. Under specific reaction conditions in the application, the yield of the silver-palladium-based catalyst catalyzed photo-induced C-C coupling reaction is as high as 98%, and the catalyst can be applied to various different substrates. In addition, the yield of the silver-palladium-based catalyst does not change significantly after being reused for 5 times. The application closely combines plasmons with high visible light absorption capacity and metal Pd with high catalytic activity, and the catalytic system can effectively promote the conversion of solar energy into chemical energy under mild conditions, opening up a new outlet for visible light driven catalytic materials for organic coupling reactions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of C-C bond construction, and particularly relates to application of a silver-palladium-based catalyst in a photo-induced C-C coupling reaction and a method thereof. BACKGROUND

[0002] C-C coupling reaction is a key step in the transformation and synthesis of a large number of natural products. According to the characteristics of the reaction process, the coupling reaction can be divided into two types: self-coupling reaction and cross-coupling reaction. The synthesis of biaryl compounds, the product of C-C coupling reaction, has important significance in chemistry, and is widely used as an intermediate in material preparation, natural products, bioactive compounds and the like. Among them, the application of palladium-catalyzed Suzuki coupling reaction, Heck coupling reaction and Sonogashira coupling reaction has attracted more and more attention. The palladium-catalyzed Suzuki coupling reaction is a very powerful C-C bond construction approach, but due to the high activation energy barrier of the substrate in the reaction, most reactions, especially heterogeneous palladium-catalyzed reactions, rely on relatively high reaction temperature. Therefore, it is of great significance to design a heterogeneous catalytic system that can be applied to Suzuki coupling reaction and can effectively reduce the reaction temperature and improve the catalytic activity and conversion efficiency. SUMMARY

[0003] The present application aims to overcome the problems in the prior art, and provides application of a silver-palladium-based catalyst in a photo-induced C-C coupling reaction and a method thereof.

[0004] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0005] The present application provides application of a silver-palladium-based catalyst in a photo-induced C-C coupling reaction.

[0006] The present application also provides a method for application of a silver-palladium-based catalyst in a photo-induced C-C coupling reaction, comprising the following steps:

[0007] Under a protective atmosphere, halogenated aromatic hydrocarbons, phenylboronic acid substances, potassium carbonate, a silver-palladium-based catalyst and a solvent are mixed to perform a photo-induced C-C coupling reaction, and a product is obtained.

[0008] As a preferred, the halogenated aromatic hydrocarbons are iodobenzene, 4-iodoanisole, 4-iodotoluene, 4-fluoroiodobenzene, 1,4-diiodobenzene, bromobenzene or 4-bromotoluene.

[0009] As a preferred, the phenylboronic acid substances are phenylboronic acid, 4-bromophenylboronic acid, 4-fluorophenylboronic acid, 4-chlorophenylboronic acid, 4-methoxyphenylboronic acid, 4-methylphenylboronic acid or 4-nitrophenylboronic acid.

[0010] As preferred, the solvent comprises ethanol and water, and the volume ratio of the ethanol and water is 1.5-2.5: 1.5-2.5.

[0011] As preferred, the molar volume ratio of the halogenated aromatic hydrocarbon, the phenylboronic acid substance, the potassium carbonate and the solvent is 0.3-0.7 mmol: 0.4-0.8 mmol: 1.3-1.7 mmol: 3-5 mL.

[0012] As preferred, the mass volume ratio of the silver-palladium-based catalyst and the solvent is 1-5 mg: 3-5 mL.

[0013] As preferred, the light wavelength of the reaction is 450-470 nm, and the power of the reaction is 20-30 w.

[0014] As preferred, the temperature of the reaction is 20-30℃, and the time of the reaction is 1-12 h.

[0015] The beneficial effects of the present application are:

[0016] (1) The present application successfully prepares an AgPd bimetallic-loaded functionalized graphene oxide composite photocatalyst with surface plasmon resonance effect by using only light energy to mediate the reduction of metals Ag and Pd without the aid of any additional reducing agent, and uses it as a kind of efficient photocatalyst for Suzuki coupling reaction under visible light induction. The high specific surface area, efficient electron transmission rate and wide range of light response characteristics of graphene oxide not only can improve the absorption of visible light, but also can quickly transmit the photo-generated hot electrons to the active site, and can provide enough adsorption sites to adsorb organic molecules, thereby enhancing the photocatalytic activity. By using the local surface plasmon resonance effect of the plasmonic active metal Ag, the surface electron density of the metal Pd is enhanced, which promotes the conversion of solar energy to chemical energy. The various characterization analysis results show that the presence of plasmonic components can easily and effectively absorb light energy, and through the LSPR effect, photo-generated hot electrons are generated and transferred to the active site Pd, which promotes the coupling reaction. The energy of the plasmonic excitation-induced hot electrons is much higher than that of ordinary electrons, and it is easier to inject into the adsorbed halogenated aryl group to break the C-X bond. The present application closely combines the plasmonic component with high visible light absorption capacity and the metal Pd with high catalytic activity, so that the light energy collected by the plasmonic component can be directly utilized by the catalytically active component. This catalytic system can effectively promote the conversion of solar energy to chemical energy under mild conditions, and opens up a new outlet for visible light-driven catalytic materials for organic coupling reactions.

[0017] (2) Under the specific reaction conditions of the present application, the yield of the silver palladium-based catalyst catalyzed photo-induced C-C coupling reaction is as high as 98%, and it can be applied to a variety of different substrates. In addition, the yield of the catalyst AgPd@4-tert-BzA / GO does not change significantly after being reused for 5 times, and it has good reusability. When the experiment is scaled up by 50 times, a yield of 80% can still be obtained, which increases the possibility of studying the industrial large-scale application of sunlight-driven chemical reactions. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Mechanism diagram of the silver palladium-based catalyst for photo-induced C-C coupling reaction in the present application;

[0019] Figure 2 Recycle—cycle number, Yeild (%)—yield (%) for the reusability of the catalyst AgPd@4-tert-BzA / GO for the coupling reaction of iodobenzene and phenylboronic acid in Example 1. DETAILED DESCRIPTION

[0020] The present application provides an application of a silver palladium-based catalyst in photo-induced C-C coupling reaction.

[0021] In the present application, the preparation method of the silver palladium-based catalyst comprises the following steps:

[0022] (1) mixing graphene oxide, ethanol, azobisisobutyronitrile and 4-tert-butyl aniline, and reacting to obtain a functionalized intercalated graphene oxide material;

[0023] (2) mixing the functionalized intercalated graphene oxide material, ethanol and silver nitrate solution, and reacting to obtain an intermediate product;

[0024] (3) mixing the intermediate product and palladium acetate solution, and reacting to obtain the silver palladium-based catalyst.

[0025] In the present application, the mass-volume ratio of the graphene oxide, ethanol and azobisisobutyronitrile in step (1) is preferably 120-180 mg: 10-20 mL: 25-35 mg, further preferably 130-170 mg: 12-18 mL: 27-33 mg, and more preferably 150-160 mg: 15-17 mL: 28-30 mg.

[0026] In the present application, the mass-mole ratio of the azobisisobutyronitrile and 4-tert-butyl aniline is preferably 25-35 mg: 9-10 mmol, further preferably 27-33 mg: 9.2-9.8 mmol, and more preferably 28-30 mg: 9.42-9.5 mmol.

[0027] In the present application, the mixing in step (1) is preferably that the graphene oxide and ethanol are initially mixed until the graphene oxide is completely dispersed, and then the azoisobutyronitrile and 4-tert-butyl aniline are added for reaction.

[0028] In the present application, the temperature of the initial mixing is preferably 20-30℃, further preferably 22-28℃, and more preferably 25-26℃; and the ultrasonic frequency of the initial mixing is preferably 60-100Hz, further preferably 70-90Hz, and more preferably 75-80Hz.

[0029] In the present application, the ultrasonic frequency of the reaction in step (1) is preferably 60-100Hz, further preferably 70-90Hz, and more preferably 75-80Hz; the temperature is preferably 20-35℃, further preferably 25-30℃, and more preferably 27-28℃; and the time is preferably 2.5-3.5h, further preferably 2.7-3.3h, and more preferably 2.8-3h.

[0030] In the present application, after the reaction in step (1) is completed, the obtained system is sequentially subjected to standing, centrifugation, washing, and freeze-drying to obtain the functionalized intercalated graphene oxide material.

[0031] In the present application, the temperature of the standing is preferably 20-30℃, further preferably 22-28℃, and more preferably 25-27℃; the time of the standing is preferably 1.5-2.5h, further preferably 1.7-2.3h, and more preferably 2-2.1h; the rotation speed of the centrifugation is preferably 8000-12000r / min, further preferably 9000-11000r / min, and more preferably 9500-10000r / min; the time of the centrifugation is preferably 5-15min, further preferably 8-12min, and more preferably 9-10min; the washing is preferably carried out by sequentially performing dimethylformamide washing, anhydrous ethanol washing, and water washing; the number of times of the dimethylformamide washing, anhydrous ethanol washing, and water washing is independently preferably ≥2 times, further preferably ≥3 times, and more preferably ≥4 times; and the temperature of the freeze-drying is preferably -70--90℃, further preferably -75--85℃, and more preferably -78--83℃; and the time of the freeze-drying is preferably 12-36h, further preferably 18-30h, and more preferably 24-26h.

[0032] In the present application, the mass concentration of the silver nitrate solution in step (2) is preferably 0.5-1.5mg / mL, further preferably 0.7-1.3mg / mL, and more preferably 0.8-1mg / mL.

[0033] In the present application, the mass-volume ratio of the functionalized intercalated graphene oxide material, ethanol and silver nitrate solution in step (2) is preferably 45-55 mg: 5-15 mL: 0.5-1.5 mL, further preferably 47-53 mg: 7-13 mL: 0.7-1.3 mL, and more preferably 48-50 mg: 8-10 mL: 0.8-1.0 mL.

[0034] In the present application, the mixing in step (2) is preferably that the functionalized intercalated graphene oxide material and ethanol are first mixed until the functionalized intercalated graphene oxide material is completely dispersed, and then the silver nitrate solution is added dropwise for reaction.

[0035] In the present application, the temperature of the preliminary mixing is preferably 20-30°C, further preferably 22-28°C, and more preferably 25-26°C; the ultrasonic frequency of the preliminary mixing is preferably 60-100 Hz, further preferably 70-90 Hz, and more preferably 75-80 Hz; and the time of the dropwise addition is preferably 10-30 min, further preferably 15-25 min, and more preferably 18-20 min.

[0036] In the present application, the xenon lamp power of the reaction in step (2) is preferably 250-350 w, further preferably 260-330 w, and more preferably 280-300 w; and the time of the reaction is preferably 0.5-1.5 h, further preferably 0.7-1.3 h, and more preferably 0.8-1.0 h.

[0037] In the present application, the mass concentration of the palladium acetate solution in step (3) is preferably 0.5-1.5 mg / mL, further preferably 0.7-1.3 mg / mL, and more preferably 0.8-1 mg / mL.

[0038] In the present application, the volume ratio of the silver nitrate solution in step (2) to the palladium acetate solution in step (3) is preferably 0.5-1.5: 0.5-1.5, further preferably 0.7-1.3: 0.7-1.3, and more preferably 0.8-1.0: 0.8-1.0.

[0039] In the present application, the mixing in step (3) is preferably that the palladium acetate solution is added dropwise to the intermediate product for reaction; and the time of the dropwise addition is preferably 10-30 min, further preferably 15-25 min, and more preferably 18-20 min.

[0040] In the present application, the xenon lamp power of the reaction in step (3) is preferably 250-350 w, further preferably 260-330 w, and more preferably 280-300 w; and the time of the reaction is preferably 8-12 h, further preferably 9-11 h, and more preferably 9.5-10 h.

[0041] In the present application, after the reaction of step (3) is completed, the obtained system is sequentially subjected to centrifugation, washing and vacuum drying to obtain the silver-palladium-based catalyst.

[0042] In the present application, the rotation speed of the centrifugation is preferably 8000-12000 r / min, further preferably 9000-11000 r / min, and more preferably 9500-10000 r / min; the centrifugation time is preferably 5-15 min, further preferably 8-12 min, and more preferably 9-10 min; the washing is preferably carried out by sequentially washing with anhydrous ethanol and water; the number of times of washing with anhydrous ethanol and water is independently preferably ≥ 2 times, further preferably ≥ 3 times, and more preferably ≥ 4 times; and the vacuum drying is preferably carried out in a vacuum drying oven at a vacuum degree of 1x10 4 -6 Pa; the temperature of the vacuum drying is preferably 55-65℃, further preferably 57-63℃, and more preferably 58-60℃; and the vacuum drying time is preferably 7-9 h, further preferably 7.5-8.5 h, and more preferably 8-8.3 h.

[0043] The present application also provides a method for applying the silver-palladium-based catalyst in a photo-induced C-C coupling reaction, comprising the following steps:

[0044] Under a protective atmosphere, a halogenated aromatic hydrocarbon, a phenylboronic acid substance, potassium carbonate, a silver-palladium-based catalyst and a solvent are mixed to carry out a photo-induced C-C coupling reaction to obtain a product.

[0045] In the present application, the halogenated aromatic hydrocarbon is preferably iodobenzene, 4-iodoanisole, 4-iodotoluene, 4-fluoroiodobenzene, 1,4-diiodobenzene, bromobenzene or 4-bromotoluene.

[0046] In the present application, the phenylboronic acid substance is preferably phenylboronic acid, 4-bromophenylboronic acid, 4-fluorophenylboronic acid, 4-chlorophenylboronic acid, 4-methoxyphenylboronic acid, 4-methylphenylboronic acid or 4-nitrophenylboronic acid.

[0047] In the present application, the solvent preferably comprises ethanol and water, and the volume ratio of the ethanol and water is preferably 1.5-2.5: 1.5-2.5, further preferably 1.7-2.3: 1.7-2.3, and more preferably 1.8-2.0: 1.8-2.0.

[0048] In the present application, the molar volume ratio of the halogenated aromatic hydrocarbon, the phenylboronic acid substance, the potassium carbonate and the solvent is preferably 0.3-0.7 mmol: 0.4-0.8 mmol: 1.3-1.7 mmol: 3-5 mL, further preferably 0.35-0.65 mmol: 0.45-0.75 mmol: 1.35-1.65 mmol: 3.6-4.6 mL, and more preferably 0.5-0.6 mmol: 0.5-0.6 mmol: 1.5-1.6 mmol: 4-4.2 mL.

[0049] In the present application, the mass volume ratio of the silver palladium-based catalyst and the solvent is preferably 1-5 mg: 3-5 mL, further preferably 2-4 mg: 3.5-4.5 mL, and more preferably 2.5-3 mg: 4-4.2 mL.

[0050] In the present application, the protective atmosphere is preferably set by the following steps: introducing a protective gas to expel air in the system, then protecting for a certain time, and then performing the reaction; the protective gas is preferably nitrogen, argon or helium; the time for the protection for a certain time is preferably 8-12 min, further preferably 9-11 min, and more preferably 10-10.5 min.

[0051] In the present application, when the halogenated aromatic hydrocarbon is iodobenzene and the phenylboronic acid substance is phenylboronic acid, the equation of the reaction is as follows:

[0052]

[0053] In the present application, the reaction is preferably performed under the irradiation of an LED lamp, the light wavelength of the reaction is preferably 450-470 nm, further preferably 455-465 nm, and more preferably 460-462 nm; the power of the reaction is preferably 20-30 w, further preferably 22-28 w, and more preferably 25-26 w; a fan is used for heat dissipation during the reaction, so as to ensure that the reaction is induced by light, rather than the heat generated by the light irradiation.

[0054] In the present application, the temperature of the reaction is preferably 20-30℃, further preferably 22-28℃, and more preferably 25-26℃; the time of the reaction is preferably 1-12 h, further preferably 1.5-8 h, and more preferably 2-3 h.

[0055] In the present application, after the reaction is completed, a membrane filter is used to filter and separate the catalyst, the obtained filtrate is extracted, the organic phase is collected, anhydrous sodium sulfate is added to the organic phase for drying, then the anhydrous sodium sulfate is filtered and separated using filter paper, after the separation is completed, a rotary evaporator is used for concentration, and finally, silica gel column chromatography is used for separation and purification, and the yield is calculated.

[0056] In the present application, the filter membrane pore of the membrane filter is preferably 0.4-0.5 μm, further preferably 0.42-0.47 μm, and more preferably 0.45-0.46 μm; the extraction reagent is preferably ethyl acetate, the extraction times are preferably ≥2 times, further preferably ≥3 times, and more preferably ≥4 times; the volume / mass ratio of ethyl acetate to the silver-palladium-based catalyst for single extraction is preferably 8-12 mL: 1-5 mg, further preferably 9-11 mL: 2-4 mg, and more preferably 10-10.5 mL: 2.5-3 mg; the volume of anhydrous sodium sulfate to ethyl acetate for single extraction is preferably 20-25 mg: 8-12 mL, further preferably 21-24 mg: 9-11 mL, and more preferably 22-23 mg: 10-10.5 mL; the drying temperature is preferably 20-30 °C, further preferably 22-28 °C, and more preferably 25-26 °C; the drying time is preferably 25-35 min, further preferably 27-33 min, and more preferably 28-30 min; the concentration temperature is preferably 25-45 °C, further preferably 30-42 °C, and more preferably 35-40 °C; the concentration time is preferably 5-20 min, further preferably 8-15 min, and more preferably 10-12 min; the particle size of the silica gel is preferably 100-300 mesh, further preferably 120-200 mesh, and more preferably 160-180 mesh; and the eluent of the column chromatography is preferably petroleum ether.

[0057] In the present application, the mechanism diagram of the silver-palladium-based catalyst for photo-induced C-C coupling reaction is shown in Figure 1 Figure 1 ​As can be seen, the catalytic process is mainly divided into two parts, the first part is the activation of active metal Pd on the catalyst. Under visible light irradiation, AgNPs absorb light energy, the surface plasmon resonance effect excites the Ag surface, so that the Ag surface is enriched with electrons, and the generated photo-generated electrons are transferred to the functional intercalation graphene oxide material, and then quickly transferred to the Pd nanoparticles, so that the metal palladium surface is enriched with electrons, and the electron density of the Pd site is increased, and the intrinsic activity in the coupling reaction is enhanced. The second part is to initiate the catalytic synthesis. The rate-determining step of the photo-induced coupling reaction is the rupture of the C-I bond. It is found through the experiment of adding a hole scavenger that the photo-generated hole is the key to the coupling reaction. AgNPs capture the radiation photons through the local surface plasmon resonance phenomenon and generate hot electrons, and then transfer these hot electrons to the Pd surface. The Pd surface is enriched with electrons, so that the C-I bond on iodobenzene is more active, forming an [Ar-Pd-I] species. The hole generated by photoinduction splits the C-I bond and activates the phenylboronic acid at the same time. The oxidized phenylboronic acid moves to the position of the activated [Ar-Pd-I] species, and then promotes the coupling to form biphenyl. At the same time, in the process of coupling reaction consuming the Pd surface enriched electrons, AgNPs continuously absorb light energy, capture the radiation photons through the local surface plasmon resonance phenomenon and generate hot electrons, and continuously transfer these hot electrons to the Pd surface for the coupling reaction to proceed.

[0058] The technical solutions provided by the application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the application.

[0059] Example 1

[0060] Mix 150 mg of graphene oxide and 15 mL of ethanol at a temperature of 25°C and a frequency of 80 Hz until the graphene oxide is completely dispersed, then add 30 mg of azoisobutyronitrile and 9.42 mmol of 4-tert-butyl aniline, and react under the condition of ultrasonic frequency of 80 Hz and temperature of 30°C for 3 h. After the reaction is completed, the obtained system is placed at 25°C for 2 h, then centrifuged at a speed of 10000 r / min for 10 min, and the product is collected. Wash with dimethylformamide for 3 times, anhydrous ethanol for 3 times, and water for 3 times, and finally freeze-dried at-80°C for 24 h to obtain the functional intercalation graphene oxide material (marked as 4-tert-BzA / GO).

[0061] The 50 mg functional intercalated graphene oxide material and 10 mL ethanol were mixed at a temperature of 25°C and a frequency of 80 Hz until the functional intercalated graphene oxide material was completely dispersed, and then 1 mL of a silver nitrate solution with a mass concentration of 1 mg / mL was added dropwise (the dropwise adding time was 20 min), and the intermediate product was obtained after reaction for 1 h under irradiation of a 300 w xenon lamp; 1 mL of a palladium acetate solution with a mass concentration of 1 mg / mL was added dropwise to the intermediate product (the dropwise adding time was 20 min), and the reaction was continued for 10 h under irradiation of a 300 w xenon lamp; after the reaction was completed, the product was collected by centrifugation at a speed of 10,000 r / min for 10 min, washed with anhydrous ethanol twice and water twice, and finally vacuum dried at a vacuum degree of 10,000 Pa and a temperature of 60°C for 8 h, to obtain the silver-palladium-based catalyst (labeled as AgPd@4-tert-BzA / GO).

[0062] The 0.5 mmol iodobenzene, 0.6 mmol phenylboronic acid, 1.5 mmol potassium carbonate, 2 mg silver-palladium-based catalyst, 2 mL ethanol and 2 mL water were mixed, argon was introduced to remove air in the system, and then the system was protected for 10 min; the reaction was carried out at 25°C for 2 h under irradiation of a 25 w LED lamp (light wavelength was 460 nm), and a fan was used for heat dissipation during the reaction; after the reaction was completed, the catalyst was separated by filtration using a membrane filter with a pore size of 0.45 μm; the obtained filtrate was extracted 3 times (the extraction reagent was ethyl acetate, and the volume of ethyl acetate used for single extraction was 10 mL), and the organic phase was collected; 20 mg of anhydrous sodium sulfate was added to the organic phase, and the mixture was dried at 25°C for 30 min; the anhydrous sodium sulfate was separated by filtration using filter paper; after the separation was completed, the product was obtained by concentration for 10 min at 35°C using a rotary evaporator; and finally, the product was separated and purified by silica gel column chromatography (the silica gel particle size was 160 mesh, and the eluent was petroleum ether) (labeled as No. 7).

[0063] While other conditions were controlled, the reaction conditions (reaction solvent, amount of silver-palladium-based catalyst or reaction time) were changed according to Table 1, to obtain the product; and the yield comparison results of the AgPd@4-tert-BzA / GO light-induced C-C coupling reaction under different conditions were calculated, as shown in Table 1.

[0064] Table 1: Yield comparison results of the AgPd@4-tert-BzA / GO light-induced C-C coupling reaction under different conditions

[0065] Serial number Reaction solvent Catalyst amount / mg Reaction time / h Yield / % 1 Water 2 mL 1 12 87 2 Ethanol 2 mL 2 12 98 3 Water 2 mL 5 12 96 4 Ethanol 2 mL 2 12 71 5 Water 2 mL 2 12 73 6 Ethanol 2 mL 2 1 83 7 Water 2 mL 2 2 98 8 Ethanol 2 mL 2 5 94 9 Water 2 mL 2 2 36 10 Ethanol 2 mL 2 2 55 11 Water 2 mL 2 2 64

[0066] In Table 1, serial numbers 1-6 and serial number 8 are consistent with the conditions in Table 1 except that the conditions are inconsistent with serial number 7; serial number 9 additionally adds 0.5 mL of hole scavenger TEOA during the reaction, and the rest of the conditions are consistent with serial number 7; serial number 10 additionally adds 0.5 mL of radical scavenger benzoquinone during the reaction, and the rest of the conditions are consistent with serial number 7; serial number 11 is carried out under an air atmosphere, and the rest of the conditions are consistent with serial number 7.

[0067] As can be seen from Table 1, by comparing the amount of silver-palladium-based catalyst, it is found that only 2 mg of silver-palladium-based catalyst can obtain a yield of 98%; the effect of the reaction solvent on the reaction is investigated, and the results show that when using inorganic base (potassium carbonate) as the necessary base in the reaction, it needs to be dissolved in water, and the reactant is an organic molecule and is not soluble in water, so ethanol is used as a solvent to mix it with the base, so that the reactant and the catalyst can better contact to ensure that the reaction proceeds fully; the effect of reaction time is investigated while keeping the amount of catalyst and the ratio of reaction solvent unchanged, and the results show that when using 2 mg of silver-palladium-based catalyst, 2 h can harvest a yield of more than 98%. The effect of the reaction environment on the coupling reaction is investigated, and the results show that the yield decreases to 64% under an air system, because in an argon environment, Ar can prevent the oxidation of the reactant and the catalyst, and dissolved oxygen in the air can combine with photo-generated electrons to produce superoxide radicals, which can decompose adsorbed organic molecules and consume photo-generated electrons, which is not conducive to improving the electron density of palladium in the catalyst and is not conducive to the reaction. Therefore, the optimal reaction conditions are determined as follows: water:ethanol = 1:1 (2 mL each) as the solvent, adding AgPd@4-tert-BzA / GO catalyst 2 mg, using a 25 w LED lamp (λ = 460 nm) to irradiate the reaction under Ar environment at room temperature for 2 h. In addition, to explore the attribution of the active species that promotes the light-induced C-C coupling reaction, TEOA is used as a hole scavenger, and the yield of the coupling product obtained by the final reaction is only 36%, and benzoquinone is used as a radical scavenger, and the yield of the coupling product obtained by the final reaction is 55%. This result shows that the photo-generated hole-electron pair plays a crucial role in the light-induced coupling reaction.

[0068] The comparative example 1 of the present embodiment is set, and the other conditions in the example 1 are controlled to be unchanged, and the step of adding palladium acetate solution for continuous reaction is omitted to obtain a silver-based catalyst (marked as Ag@4-tert-BzA / GO).

[0069] The comparative example 2 of the present embodiment is set, and the other conditions in the example 1 are controlled to be unchanged, and the step of adding silver nitrate solution for reaction is omitted to obtain a palladium-based catalyst (marked as Pd@4-tert-BzA / GO).

[0070] The comparative example 3 of the present embodiment is set, and the functional intercalated graphene oxide material is replaced by graphene oxide material under the condition of the other conditions in the example 1 unchanged to obtain a silver palladium loaded graphene oxide composite catalyst (marked as AgPd@GO).

[0071] Under the optimal reaction conditions, the yield of the light-induced C-C coupling reaction of the catalysts silver nitrate, palladium acetate, Ag@4-tert-BzA / GO, Pd@4-tert-BzA / GO, AgPd@GO and AgPd@4-tert-BzA / GO is tested respectively, and the yield comparison results of the light-induced C-C coupling reaction under different catalyst systems are obtained as shown in Table 2.

[0072] Table 2 Yield comparison results of light-induced C-C coupling reaction under different catalyst systems

[0073]

[0074]

[0075] From Table 2, it can be seen that no product is generated when silver nitrate is used as a catalyst, and 27% yield can be obtained when palladium acetate is used as a catalyst, and almost no coupling product is generated when the catalyst Ag@4-tert-BzA / GO is used to catalyze the coupling reaction, and 51% yield can be obtained when the catalyst Pd@4-tert-BzA / GO is used, and only 71% yield is obtained when the catalyst AgPd@GO is used. This result shows that the combination of metal Pd and photocatalyst with light response is the key driving force to promote photocatalytic coupling reaction. When the functionalized graphene oxide 4-tert-BzA / GO with larger interlayer spacing and larger pore size is used as a carrier for metal loading, the organic molecules can better contact with the active center, and the catalytic activity of the active center can be maximized, so as to achieve high yield.

[0076] The reaction substrate is changed, and the rest of the reaction conditions are set as the optimal reaction conditions. The reaction substrate is selected according to Table 3. The comparison results of the catalytic efficiency of the catalyst AgPd@4-tert-BzA / GO for different substrate coupling reactions are tested, and the obtained results are recorded in Table 3.

[0077] Table 3 Comparison results of catalytic efficiency of catalyst AgPd@4-tert-BzA / GO for different substrate coupling reactions

[0078]

[0079]

[0080] It can be found from Table 3 that when the reaction substrate is iodobenzene, the substituent group on the phenylboronic acid can be well obtained regardless of the electron-withdrawing group or the electron-donating group (> 80%); the substituent group on the iodoarene has little effect on the reaction. For the weaker reactivity of the bromoarene, the coupling reaction can also be well carried out.

[0081] The reusability of the catalyst AgPd@4-tert-BzA / GO for the coupling reaction of iodobenzene and phenylboronic acid was tested, and the reusability of the catalyst AgPd@4-tert-BzA / GO for the coupling reaction of iodobenzene and phenylboronic acid was obtained, as shown in Ethanol 2 mL

[0082] It can be seen from Figure 2 Figure 2 that the yield of the catalyst AgPd@4-tert-BzA / GO does not change significantly after being reused for 5 times, and the yield begins to decrease slightly after 5 times. In addition, 80% yield can still be obtained when the experiment is enlarged by 50 times. This result increases the possibility of studying the industrial large-scale application of sunlight-driven chemical reactions.

[0083] Example 2

[0084] 0.65 mmol of 4-fluoroiodobenzene, 0.75 mmol of phenylboronic acid, 1.65 mmol of potassium carbonate, 3 mg of the silver-palladium-based catalyst prepared in Example 1, 2.3 mL of ethanol and 2.3 mL of water were mixed, and nitrogen was introduced to remove air in the system. Then, it was protected for 12 min, and irradiated under a 28 w LED lamp (light wavelength 465 nm) at 26°C for 1.5 h. During the reaction, a fan was used for cooling. After the reaction, a filter membrane with a pore size of 0.5 μm was used to filter and separate the catalyst. The obtained filtrate was extracted 4 times (the extraction reagent was ethyl acetate, and the volume of ethyl acetate used for single extraction was 11 mL), and the organic phase was collected. Then, 25 mg of anhydrous sodium sulfate was added, and dried at 28°C for 27 min. After that, the anhydrous sodium sulfate was separated by filtration using filter paper. After separation, the rotary evaporator was used to concentrate at 25°C for 20 min. Finally, silica gel column chromatography (the particle size of silica gel was 200 mesh, and the eluent was petroleum ether) was used for separation and purification, and the product was obtained.

[0085] The yield of the product obtained in this example was calculated, and the yield of the silver-palladium-based catalyst catalyzed photo-induced C-C coupling reaction in this example was 90%.

[0086] Example 3

[0087] ​Mix 0.35 mmol of 1,4-diiodobenzene, 0.45 mmol of phenylboronic acid, 1.35 mmol of potassium carbonate, 1 mg of the silver palladium-based catalyst prepared in Example 1, 1.8 mL of ethanol and 1.8 mL of water, and then purge the system of air by introducing helium. Then, under the irradiation of a 22-w LED lamp (light wavelength: 455 nm) for 3 h at 22°C, use a fan to dissipate heat during the reaction. After the reaction, filter and separate the catalyst using a membrane filter with a pore size of 0.4 μm, extract the filtrate three times (using 9 mL of ethyl acetate each time), collect the organic phase, add 22 mg of anhydrous sodium sulfate to the organic phase, and then dry at 22°C for 33 min. Then, filter and separate the anhydrous sodium sulfate using filter paper, and then concentrate the filtrate using a rotary evaporator at 45°C for 5 min. Finally, separate and purify the product using a silica gel column (silica gel particle size: 200 mesh, eluent: petroleum ether).

[0088] The yield of the product obtained in this example was calculated, and the yield of the silver palladium-based catalyst in the photo-induced C-C coupling reaction in this example was 85%.

[0089] As can be seen from the above examples, the application provides a method for applying a silver palladium-based catalyst in a photo-induced C-C coupling reaction. In a protective atmosphere, halogenated aromatic hydrocarbons, phenylboronic acid substances, potassium carbonate, a silver palladium-based catalyst and a solvent are mixed to perform a photo-induced C-C coupling reaction to obtain a product. Under the specific reaction conditions of the application, the yield of the silver palladium-based catalyst in the photo-induced C-C coupling reaction is as high as 98%, and the catalyst can be applied to a variety of different substrates. In addition, the yield of the catalyst AgPd@4-tert-BzA / GO does not change significantly after being reused 5 times, and the catalyst has good reusability. When the experiment is scaled up by 50 times, a yield of 80% can still be obtained, which increases the possibility of studying the industrialization of large-scale application of sunlight-driven chemical reactions.

[0090] The above only describes the preferred embodiments of the application, and it should be noted that those of ordinary skill in the art can make several improvements and refinements without departing from the principles of the application, and these improvements and refinements should also be considered within the protection scope of the application.

Claims

1. The application of a silver-palladium-based catalyst in photoinduced C-coupling reactions, characterized in that, The method of application includes the following steps: Under a protective atmosphere, haloaromatics, phenylboronic acid, potassium carbonate, silver-palladium-based catalyst and solvent were mixed and subjected to photoinduced CC coupling reaction to obtain the product; The silver-palladium-based catalyst is an AgPd bimetallic supported functionalized graphene oxide composite photocatalyst. The preparation method of the silver-palladium-based catalyst includes the following steps: (1) Graphene oxide, ethanol, azoisobutyronitrile and 4-tert-butylaniline were mixed and reacted to obtain functionalized intercalated graphene oxide material. (2) The functionalized intercalated graphene oxide material, ethanol and silver nitrate solution were mixed and reacted under xenon lamp irradiation to reduce silver and obtain intermediate product. (3) The intermediate product and palladium acetate solution were mixed and reacted under xenon lamp irradiation to reduce palladium and obtain the silver palladium-based catalyst. The solvent comprises ethanol and water, wherein the volume ratio of ethanol to water is 1.5–2.5:1.5–2.5; The mass-volume ratio of the silver-palladium-based catalyst to the solvent is 1–5 mg: 3–5 mL.

2. The application as described in claim 1, characterized in that, The halogenated aromatic hydrocarbon is iodobenzene, 4-iodoanisole, 4-iodotoluene, 4-fluoroiodobenzene, 1,4-diiodobenzene, bromobenzene, or 4-bromotoluene.

3. The application as described in claim 1 or 2, characterized in that, The phenylboronic acid substances are phenylboronic acid, 4-bromophenylboronic acid, 4-fluorophenylboronic acid, 4-chlorophenylboronic acid, 4-methoxyphenylboronic acid, 4-methylphenylboronic acid, or 4-nitrophenylboronic acid.

4. The application as described in claim 1, characterized in that, The molar volume ratio of the halogenated aromatic hydrocarbon, phenylboronic acid, potassium carbonate, and solvent is 0.3–0.7 mmol: 0.4–0.8 mmol: 1.3–1.7 mmol: 3–5 mL.

5. The application as described in claim 4, characterized in that, The wavelength of the light induced by the CC coupling reaction is 450–470 nm, and the power is 20–30 W.

6. The application as described in claim 4, characterized in that, The photoinduced CC coupling reaction is carried out at a temperature of 20–30°C for 1–12 hours.

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