Method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2 (at) RGO composite material

Abstract

The invention belongs to the technical field of catalytic synthesis, and particularly relates to a method for catalyzing a Suzuki reaction based on a Pd / UiO-66-NH2 (at) RGO composite material. According to the technical scheme, ZrCl4, 2-aminoterephthalic acid, graphene oxide, DMF and glacial acetic acid are sequentially added into a reaction kettle, stirred for 0.5 h and placed in a 473 K drying oven to react for 12 h, the mixture is cooled to the room temperature and then centrifuged, washed and dried in vacuum, Pd is loaded through an equivalent impregnation method, and the catalyst is obtained. Catalyzing Suzuki reaction of the obtained composite material Pd / UiO-66-NH2 (at) RGO, iodobenzene, phenylboronic acid and potassium carbonate in a reaction container, and reacting for 1 hour under the condition of 353 K; the preparation method of the Pd / UiO-66-NH2 (at) RGO provided by the invention is simple, and the Pd / UiO-66-NH2 (at) RGO shows ultrahigh catalytic ability in a Suzuki reaction.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic synthesis, and in particular relates to a method for catalyzing Suzuki reaction based on a Pd / UiO-66-NH2@RGO composite material. Background Art

[0002] Metal-organic frameworks (MOFs) are porous coordination polymers formed by inorganic metal centers and multidentate organic ligands (such as nitrogen, oxygen or aromatic acids) bridged by strong coordination. MOFs have a 2D or 3D structure and are a new type of porous material that has been widely studied and applied in recent years. Due to their large specific surface area and pore volume, MOFs materials exhibit high catalytic activity and selectivity in catalytic reactions. Their porous structure can provide a large number of active sites, increase the adsorption and diffusion rate of reactants, and thus improve the reaction efficiency. MOFs materials play an important role in the fields of catalysis, gas storage and separation, drug delivery, and chemical sensing.

[0003] Suzuki reaction, also known as Suzuki coupling reaction, Suzuki-Miyaura reaction, is a relatively new organic coupling reaction. It is a coupling reaction that occurs with transition metals as catalysts, aromatic or alkenyl boronic acids or boronic esters and olefins or halogenated aromatic hydrocarbons as substrates. Compared with other coupling reactions, Suzuki reaction has fewer by-products, mild reaction conditions, and organic substrates can stably exist in the air, with certain substrate adaptability and functional group tolerance. Suzuki reaction can be widely used in the fields of pharmaceuticals, electronics industry, and advanced materials, and can create more complex organic molecules.

[0004] Suzuki reaction often uses metal Pd nanoparticles as catalysts, but metal Pd often undergoes agglomeration and self-oxidation during the catalytic process, resulting in low catalytic efficiency and short life. Therefore, Pd nanoparticles are loaded into the MOFs material UiO-66-NH2. Since UiO-66-NH2 has a unique pore structure, it will inhibit the agglomeration of Pd nanoparticles and evenly distribute the Pd nanoparticles in the pore structure. However, it still has problems such as poor electronic conductivity, limited contact area between the catalyst and the substrate, and difficulty in separation.

[0005] Graphene oxide (GO) is a two-dimensional planar carbon material with high specific surface area, excellent electronic conductivity, strong hydrophilicity and good chemical stability. Its surface is rich in functional groups such as carboxyl, hydroxyl and epoxy, which provide good binding sites for the in-situ growth of MOFs. MOF / GO composite materials use their respective performance advantages and the synergistic effect of the two, so that MOF / GO composite materials have better performance and wider application in the fields of CO2 capture, gas separation, catalysis, supercapacitors, etc. Therefore, UiO-66-NH2@GO composite materials that inherit the excellent performance of their respective parent materials can be designed to solve the problems of poor electronic conductivity after UiO-66-NH2 is loaded with Pd. And it is more promising in improving catalytic efficiency in the field of catalysis. Summary of the invention

[0006] The purpose of the present invention is to provide a method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material.

[0007] The technical solution adopted by the present invention is:

[0008] A method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material comprises the following steps: taking iodobenzene, phenylboric acid, potassium carbonate and a catalyst in a reaction container, and reacting at 353K for 1 hour; the catalyst is a Pd / UiO-66-NH2@RGO composite material.

[0009] Furthermore, in the above-mentioned method of catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material, the molar ratio of iodobenzene:phenylboric acid:potassium carbonate is 1:1.5:3.

[0010] Furthermore, the above-mentioned method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material, the preparation method of the Pd / UiO-66-NH2@RGO composite material comprises the following steps:

[0011] 1) ZrCl4, 2-aminoterephthalic acid, graphene oxide GO, DMF, and glacial acetic acid were added to a reactor in sequence, stirred for 0.5 h, placed in an oven at 473 K for reaction for 12 h, cooled to room temperature after the reaction, washed with DMF and ethanol in sequence, and dried in vacuum to obtain the precursor UiO-66-NH2@GO;

[0012] 2) mixing palladium chloride, sodium chloride and methanol until dissolved, stirring overnight to obtain a sodium chloropalladate solution;

[0013] 3) Mix and disperse UiO-66-NH2@GO and sodium chloropalladate solution evenly; add sodium borohydride to the methanol solution, sodium borohydride and methanol release hydrogen, quickly absorb the upper layer of liquid with bubbles and add it to the mixed solution of UiO-66-NH2@GO and sodium chloropalladate, continue stirring for 0.5h, wash with methanol, and vacuum dry to obtain Pd / UiO-66-NH2@RGO composite material.

[0014] Furthermore, in the preparation method of the above-mentioned Pd / UiO-66-NH2@RGO composite material, in step 1), the molar ratio of ZrCl4:2-aminoterephthalic acid is 1:1.

[0015] Furthermore, in the preparation method of the above-mentioned Pd / UiO-66-NH2@RGO composite material, in step 1), the amount of graphene oxide GO added is 0.163 g.

[0016] Furthermore, in the preparation method of the above-mentioned Pd / UiO-66-NH2@RGO composite material, in step 1), 1 mL of DMF is added for every 5 mg of graphene oxide GO.

[0017] Furthermore, in the preparation method of the above-mentioned Pd / UiO-66-NH2@RGO composite material, in step 1), the vacuum drying condition is 423K vacuum drying for 12 hours.

[0018] Furthermore, in the preparation method of the above-mentioned Pd / UiO-66-NH2@RGO composite material, in step 2), the concentration of the obtained sodium chloropalladate solution is 0.17 mol / L.

[0019] Furthermore, in the preparation method of the above-mentioned Pd / UiO-66-NH2@RGO composite material, in step 3), the vacuum drying condition is 333K vacuum drying for 6 hours.

[0020] The beneficial effects of the present invention are:

[0021] 1. In the Pd / UiO-66-NH2@RGO composite material, Pd nanoparticles are highly dispersed in the pores of UiO-66-NH2, which effectively prevents the aggregation of Pd nanoparticles. Graphene oxide (GO) is a two-dimensional planar carbon material with high specific surface area, excellent electronic conductivity, strong hydrophilicity and good chemical stability. GO can provide a good binding site for the in-situ growth of MOFs. UiO-66-NH2 grows on the two-dimensional plane of graphene oxide, which further promotes the dispersion of the catalyst and increases the contact area of ​​the Pd catalytic site, thereby improving the stability of the catalyst. The combination of the two not only increases the reaction rate, but also significantly reduces the generation of by-products.

[0022] 2. During the catalytic Suzuki reaction, Pd(0) first undergoes an oxidation-addition reaction with halogenated aromatic hydrocarbons to form a Pd(II) complex, then undergoes a metal transfer reaction with activated boric acid, and finally generates a coupling product and regenerated Pd(0) through a reduction-elimination step. The introduction of graphene oxide (GO) significantly improves the electronic conductivity of the composite material, promotes the rapid transfer of electrons in the catalyst, and promotes the occurrence of the reduction-elimination step, thereby greatly improving the catalytic efficiency. In addition, the porous structure of UiO-66-NH2 and the high electronic conductivity of RGO form a good synergistic effect in the Pd / UiO-66-NH2@RGO composite material. This synergistic effect enables the composite material to exhibit higher catalytic activity and selectivity in catalyzing the Suzuki reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the PXRD pattern of the Pd / UiO-66-NH2@RGO composite material of the present invention.

[0024] Figure 2 This is the FT-IR spectrum of the Pd / UiO-66-NH2@RGO composite material of the present invention.

[0025] Figure 3 This is the TEM spectrum of the Pd / UiO-66-NH2@RGO composite material of the present invention.

[0026] Figure 4 This is a catalytic activity diagram of the Pd / UiO-66-NH2@RGO composite material of the present invention undergoing five cycles of catalytic reaction. DETAILED DESCRIPTION

[0027] Example 1 A method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material (I) Preparation of Pd / UiO-66-NH2@RGO

[0028] 1) ZrCl4 (0.764 g, 0.328 mmol), 2-aminoterephthalic acid (0.532 g, 0.328 mmol), and 0.163 g of graphene oxide GO were poured into a 80 mL reactor in sequence, and then 32.675 mL of DMF and 7.5 mL of 99.5% glacial acetic acid were accurately transferred into the reactor with a pipette. The reactor was placed in an oven at 473 K for 12 h. After the reaction was completed, it was cooled to room temperature, washed with DMF and ethanol in sequence, and dried at 423 K for 12 h to obtain the precursor UiO-66-NH2@GO.

[0029] 2) Accurately weigh 0.12 g of solid palladium chloride and 0.044 g of solid sodium chloride, pour into a 10 mL glass bottle, add 4 mL of methanol to the bottle, heat slightly until completely dissolved, stir overnight to obtain a 0.17 mol / L brown sodium chloropalladate solution.

[0030] 3) Accurately weigh 50 mg UiO-66-NH2@GO and place it in a 5 mL glass bottle. Use a pipette to accurately transfer 58.82 μL of sodium chloropalladate solution and inject it into the glass bottle several times to make the solution more evenly dispersed. Accurately weigh 8.62 mg of sodium borohydride solid and add it to 5 mL of methanol solution. Sodium borohydride and methanol release hydrogen. Quickly absorb the upper layer of liquid with bubbles and add it to the glass bottle. Continue stirring for half an hour. The final solution is black. Wash it with methanol three times, and finally dry it in a 333K vacuum drying oven for 6 hours to obtain a black crystalline Pd / UiO-66-NH2@RGO composite material.

[0031] Figure 1 The powder X-ray diffraction (PXRD) of Pd / UiO-66-NH2@RGO material shows that the UiO-66-NH2@GO material has good crystallinity during the synthesis and preparation process, and its structure is not destroyed during the Pd loading process.

[0032] Figure 2 is the FT-IR spectrum of Pd / UiO-66-NH2@RGO composite, indicating the successful synthesis of Pd / UiO-66-NH2@RGO.

[0033] Figure 3 This is the transmission electron microscopy (TEM) image of the Pd / UiO-66-NH2@RGO composite material. It can be seen that the synthesized Pd is well loaded on UiO-66-NH2@GO.

[0034] (II) Suzuki reaction

[0035] The reaction formula is as follows:

[0036]

[0037] Method: The Pd / UiO-66-NH2@RGO obtained in (a) was added into a 10 mL three-necked reaction vessel, and then 1 mmol iodobenzene, 1.5 mmol phenylboric acid and 3 mmol K2CO3 were added in sequence, and the reaction was carried out at 353 K for 1 h.

[0038] The yield of the product was monitored by gas chromatography (GC). During the reaction, the experimental results of the catalytic performance of Pd / UiO-66-NH2@RGO were detected by GC. As the reaction proceeded, the yield of the reaction gradually increased. When the reaction lasted for 1 hour, the yield of the reaction had reached 99% and the conversion rate was 99%.

[0039] (iii) The recyclability of the catalyst in the Suzuki reaction.

[0040] After the reaction, the reaction mixture was separated from Pd / UiO-66-NH2@RGO by centrifugal filtration, washed with methanol, filtered, and dried to recover Pd / UiO-66-NH2@RGO material.

[0041] The specific operation of the cyclic experiment: the recycled Pd / UiO-66-NH2@RGO material was used to catalyze the Suzuki reaction again at 353K for 1h.

[0042] The experimental results are as follows Figure 4 As shown, after the cycle experiment was carried out 5 times, the activity of the catalyst did not decrease significantly, indicating that the Pd / UiO-66-NH2@RGO can be recycled as a Suzuki reaction catalyst.

Claims

1. A method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material, characterized in that: The method comprises the following steps: putting iodobenzene, phenylboric acid, potassium carbonate and a catalyst in a reaction container, and reacting them at 353K for 1 hour; the catalyst is a Pd / UiO-66-NH2@RGO composite material.

2. The method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material according to claim 1, characterized in that: In molar ratio, iodobenzene:phenylboric acid:potassium carbonate=1:1.5:

3.

3. The method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material according to claim 1, characterized in that: The preparation method of the Pd / UiO-66-NH2@RGO composite material comprises the following steps: 1) ZrCl4, 2-aminoterephthalic acid, graphene oxide GO, DMF, and glacial acetic acid were added to a reactor in sequence, stirred for 0.5 h, placed in an oven at 473 K for reaction for 12 h, cooled to room temperature after the reaction, washed with DMF and ethanol in sequence, and dried in vacuum to obtain the precursor UiO-66-NH2@GO; 2) mixing palladium chloride, sodium chloride and methanol until dissolved, stirring overnight to obtain a sodium chloropalladate solution; 3) UiO-66-NH2@GO and sodium chloropalladate solution are mixed and dispersed uniformly; sodium borohydride is added to the methanol solution, sodium borohydride and methanol release hydrogen, and the upper layer of liquid with bubbles is quickly absorbed and added to the mixed solution of UiO-66-NH2@GO and sodium chloropalladate, and stirring is continued for 0.5h, washed with methanol, and vacuum dried to obtain Pd / UiO-66-NH2@RGO composite material.

4. The method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material according to claim 3, characterized in that: In step 1), the molar ratio of ZrCl4:2-aminoterephthalic acid is 1:

1.

5. The method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material according to claim 3, characterized in that: In step 1), the amount of graphene oxide GO added is 0.163 g.

6. The method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material according to claim 3, characterized in that: In step 1), 1 mL of DMF was added for every 5 mg of graphene oxide GO.

7. The method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material according to claim 3, characterized in that: In step 1), the vacuum drying condition is 423K vacuum drying for 12 hours.

8. The method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material according to claim 3, characterized in that: In step 2), the concentration of the sodium chloropalladate solution obtained is 0.17 mol / L.

9. The method for catalyzing Suzuki reaction based on Pd / UiO-66-NH2@RGO composite material according to claim 3, characterized in that: In step 3), the vacuum drying condition is 333K vacuum drying for 6 hours.

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