A method for Suzuki reaction catalyzed by metal organic framework MOF Pickering emulsion
By using the metal organic frame MOF in Suzuki reaction, the problem of insufficient contact area of Pd nanoparticles agglomeration and catalysts is solved, efficient catalysis and catalyst recycling are achieved, and catalyzing is improved. Efficiency and stability of the reaction.
Patent Information
- Application Number
- CN202310620687.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-30
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2043-05-30
AI Technical Summary
In the Suzuki reaction, metal Pd nanoparticles are prone to agglomeration and self-oxidation during the catalytic process, resulting in low catalytic efficiency and short life. At the same time, the contact area between the catalyst and the substrate is limited, making it difficult to separate.
Pd@MIL-101 Pikeling emulsion based on metal organic frame MOF is used as a catalyst to prepare Pd@MIL-101 material by hydrothermal synthesis, and mix it with deionized water and toluene to form a stable Pikeling emulsion. The interface effect is used to improve the catalytic efficiency and the contact area between the catalyst and the substrate is increased by ultrasonic dispersion.
It effectively prevents the aggregation of Pd nanoparticles, improves catalytic efficiency, solves the problems of poor substrate solubility and low catalyst activity, and realizes the recycling of the catalyst, maintaining high-efficiency catalytic performance.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of catalytic synthesis, and in particular to a method for Suzuki tandem reaction based on metal organic framework MOF Pickering emulsion catalysis. Background Art
[0002] Metal-organic frameworks (MOFs) are porous coordination network compounds with 2D or 3D structures, which are bridged by inorganic metal centers and multidentate organic ligands such as nitrogen, oxygen or aromatic acids through strong coordination. MOFs materials belong to coordination polymers, which include materials with porous structures, non-porous structures, and crystalline and amorphous materials. They are a new type of porous material developed in recent years. As a new type of porous coordination polymer, MOFs materials have typical characteristics that are different from traditional coordination compounds: structural diversity, porosity, large specific surface area, unsaturated metal coordination sites, etc., which make it have a series of unique properties, thus playing an outstanding role in the fields of catalysis, gas storage / separation, drug transfer, chemical sensing, non-conductive / semi-conductive, biomedical imaging, and solar energy storage. Therefore, MOFs materials with high crystallinity and molecular-level structure can be designed, which is more promising in improving catalytic efficiency in the field of catalysis.
[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 MOFs material MIL-101(Cr). Due to its unique pore structure, MIL-101(Cr) inhibits the agglomeration of Pd nanoparticles and can evenly distribute Pd nanoparticles in the pore structure. However, as a heterogeneous catalyst, it has problems such as low mass transfer efficiency, limited contact area between the catalyst and the substrate, and difficulty in separation.
[0005] An emulsion is a liquid dispersed in another immiscible liquid in the form of droplets, where the droplets are called the dispersed phase and the surrounding liquid is called the continuous phase. Unlike traditional surfactant-stabilized emulsions, Pickering emulsions are water-oil two-phase emulsions stabilized by solid particles. The difference between Pickering emulsions and traditional emulsions is that traditional emulsions use surfactants distributed on the interface of the two phases to achieve a stable effect, while Pickering emulsions use small solid particles distributed on the interface of the two phases to form a dense interfacial film, thereby obtaining a stable emulsion. Compared with traditional emulsions, Pickering emulsions have the advantages of low toxicity and strong stability. Summary of the invention
[0006] The purpose of the present invention is to provide a method for Suzuki reaction catalyzed by metal organic framework MOF Pickering emulsion.
[0007] The technical solution adopted by the present invention is: a method for catalyzing Suzuki reaction based on metal organic framework MOF Pickering emulsion, comprising the following steps: taking iodobenzene, phenylboric acid, potassium carbonate and a catalyst in a reaction container, and reacting at 353K for 4 hours; the catalyst is based on metal organic framework MOF Pickering emulsion.
[0008] Furthermore, in the above method, the molar ratio of iodobenzene:phenylboric acid:potassium carbonate is 1:1.5:3.
[0009] Furthermore, in the above method, the metal organic framework (MOF) based Pickering emulsion is Pd@MIL-101 Pickering emulsion.
[0010] Furthermore, in the above method, the Pd@MIL-101 Pickering emulsion is prepared by mixing the Pd@MIL-101 material with deionized water and toluene.
[0011] Furthermore, in the above method, the preparation method of the Pd@MIL-101 Pickering emulsion comprises the following steps:
[0012] 1) Cr(NO3)3·9H2O, terephthalic acid, acetic acid and ultrapure water were added to a hydrothermal synthesis reactor in sequence, placed in an oven at 473K for reaction for 8 hours, cooled to room temperature after the reaction was completed, washed with DMF and ethanol in sequence, and dried in vacuum to obtain the precursor MIL-101;
[0013] 2) mixing palladium chloride, sodium chloride and methanol until dissolved, stirring overnight to obtain a sodium chloropalladate solution;
[0014] 3) Mix MIL-101 and sodium chloropalladate solution and disperse them 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 MIL-101 and sodium chloropalladate, continue stirring for 0.5h, wash with methanol, and vacuum dry to obtain Pd@MIL-101 material;
[0015] 4) The Pd@MIL-101 material was ultrasonically dispersed in deionized water, toluene was added under stirring conditions, and the mixture was shaken for 5 minutes to obtain a Pd@MIL-101 Pickering emulsion.
[0016] Furthermore, in the above method, in step 1), the molar ratio of Cr(NO3)·9H2O:terephthalic acid is 1:1.
[0017] Furthermore, in the above method, in step 1), the vacuum drying is vacuum drying at 423K for 12 hours.
[0018] Furthermore, in the above method, in step 3), the vacuum drying is vacuum drying at 333K for 6 hours.
[0019] Furthermore, in the above method, in step 4), the volume ratio of deionized water to toluene is 1:2.
[0020] The beneficial effects of the present invention are:
[0021] 1. In the Pd@MIL-101 Pickering emulsion provided by the present invention, Pd is attached to the pores of MIL-101, effectively preventing the aggregation of Pd nanoparticles, and Pd(0) undergoes oxidation-addition reaction with halogenated aromatic hydrocarbons to generate a Pd(II) complex, and then undergoes a metal transfer reaction with activated boric acid to generate a Pd(II) complex, and finally undergoes reduction-elimination to generate a product and Pd(0). In addition, due to the interfacial effect, the reaction in the Pickering emulsion has a very high catalytic efficiency, and also solves the problems of poor solubility of the substrate in the aqueous solution of the reaction system and low catalyst activity.
[0022] 2. The present invention disperses Pd@MIL-101 into the emulsion system, which can greatly increase the contact area between the substrate and the catalyst and improve the catalytic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is the PXRD pattern of the Pd@MIL-101 material in the Pd@MIL-101 Pickering emulsion of the present invention.
[0024] Figure 2 It is the TEM spectrum of Pd@MIL-101 in the Pd@MIL-101 Pickering emulsion of the present invention.
[0025] Figure 3 is an optical microscope photograph of the formed Pd@MIL-101 Pickering emulsion.
[0026] Figure 4 It is a catalytic activity diagram of the Pd@MIL-101 Pickering emulsion of the present invention for five cycles of catalytic reaction.
[0027] Figure 5 This is an optical microscopic image of an emulsion formed by a catalyst recovered after the Pd@MIL-101 Pickering emulsion of the present invention is subjected to five cycles of catalytic reaction. DETAILED DESCRIPTION
[0028] Example 1 A method for catalyzing Suzuki reaction based on metal organic framework MOF Pickering emulsion (I) Preparation of Pd@MIL-101 Pickering emulsion
[0029] 1. Pour Cr(NO3)3·9H2O (3.2 g, 0.008 mol) and terephthalic acid (1.312 g, 0.008 mol) into a 80 mL hydrothermal synthesis reactor. Then use a pipette to accurately measure 2.1708 mL of 99.5% glacial acetic acid and 40 mL of ultrapure water and add them to the reactor. Place the reactor in a 473K oven to react for 8 hours. After the reaction is completed, cool to room temperature, wash with DMF three times, then wash with ethanol three times, and finally place in a vacuum drying oven and dry at 423K for 12 hours to obtain the precursor MIL-101.
[0030] 2. Accurately weigh 0.12g of solid palladium chloride and 0.044g of solid sodium chloride, pour into a 10mL glass bottle, add 4mL of methanol to the bottle, heat slightly until completely dissolved, and stir overnight to obtain a 0.17mol / L brown sodium chloropalladate solution.
[0031] 3. Accurately weigh 50 mg of MIL-101 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 place it in a 333K vacuum drying oven and dry it for 6 hours to obtain black crystal Pd@MIL-101 material.
[0032] 4. Activation treatment of Pd@MIL-101: Take a certain amount of Pd@MIL-101 material and vacuum dry it at 363K for 12h.
[0033] 5. Weigh 50 mg of the activated Pd@MIL-101 material and ultrasonically disperse it in 1.65 mL of deionized water to obtain a Pd@MIL-101 dispersion. Add 3.3 mL of toluene to the Pd@MIL-101 dispersion under stirring and shake for 3 minutes to obtain a Pd@MIL-101 Pickering emulsion.
[0034] Figure 1 This is the powder X-ray diffraction (PXRD) of Pd@MIL-101 material, which shows that the Pd@MIL-101 material has good crystallinity during the synthesis process.
[0035] Figure 2 This is the transmission electron microscopy (TEM) image of Pd@MIL-101 material. It can be seen that the synthesized Pd is well loaded on MIL-101.
[0036] Figure 3 Figure 1 is an optical microscope photo of the formed Pd@MIL-101 Pickering emulsion. It can be seen that the droplets of the Pd@MIL-101-stabilized Pickering emulsion are evenly dispersed and uniform in size.
[0037] (II) Suzuki reaction
[0038] The reaction formula is as follows:
[0039]
[0040] Method: The Pd@MIL-101 Pickering emulsion obtained in (a) was added to 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 4 h.
[0041] The yield of the product was monitored by gas chromatography (GC). During the reaction, the experimental results of the catalytic performance of the Pd@MIL-101 Pickering emulsion tandem reaction were detected by GC. As the reaction proceeded, the yield of the reaction gradually increased. When the reaction was carried out for 4 hours, the yield of the reaction had reached 99% and the conversion rate was 99%.
[0042] (iii) The recyclability of the catalyst in the Suzuki reaction.
[0043] After the reaction, the reaction mixture was centrifuged and filtered to separate Pd@MIL-101, and then washed with methanol, filtered, and dried to recover Pd@MIL-101 material.
[0044] The specific operation of the cyclic experiment: the recycled Pd@MIL-101 material was used to prepare the Pickering emulsion to catalyze the Suzuki reaction again, and the reaction was carried out at 353K for 4h.
[0045] The experimental results are as follows Figure 4 and Figure 5 As shown in the figure, after five cycles, the activity of the catalyst did not decrease significantly, and the recovered catalyst could still stably form a Pickering emulsion, indicating that Pd@MIL-101 in the Pickering emulsion can be recycled as a Suzuki reaction catalyst.
Claims
1. A method for Suzuki reaction based on metal organic framework MOF Pickering emulsion catalysis, characterized in that: The method comprises the following steps: placing iodobenzene, phenylboric acid, potassium carbonate and a catalyst in a reaction container, and reacting at 353 K for 4 hours; the catalyst is based on a metal organic framework MOF Pickering emulsion; and the metal organic framework MOF Pickering emulsion is a Pd@MIL-101 Pickering emulsion.
2. The method according to claim 1, characterized in that In molar ratio, iodobenzene:phenylboric acid:potassium carbonate = 1:1.5:
3.
3. The method according to claim 1, characterized in that: The Pd@MIL-101 Pickering emulsion is formed by mixing the Pd@MIL-101 material with deionized water and toluene.
4. The method according to claim 3, characterized in that The method for preparing the Pd@MIL-101 Pickering emulsion comprises the following steps: 1) Cr(NO3)3•9H2O, terephthalic acid, acetic acid and ultrapure water were added to a hydrothermal synthesis reactor in sequence, placed in an oven at 473K for 8 h, cooled to room temperature after the reaction, washed with DMF and ethanol in sequence, and dried in vacuum to obtain the precursor MIL-101; 2) Mix palladium chloride, sodium chloride and methanol until dissolved, and stir overnight to obtain sodium chloropalladate solution; 3) Mix and disperse MIL-101 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 MIL-101 and sodium chloropalladate, continue stirring for 0.5h, wash with methanol, and vacuum dry to obtain Pd@MIL-101 material; 4) The Pd@MIL-101 material was ultrasonically dispersed in deionized water, toluene was added under stirring conditions, and the mixture was shaken for 5 min to obtain a Pd@MIL-101 Pickering emulsion.
5. The method according to claim 4, characterized in that In step 1), the molar ratio of Cr(NO3)•9H2O:terephthalic acid is 1:
1.
6. The method according to claim 4, characterized in that In step 1), the vacuum drying is performed at 423 K for 12 h.
7. The method according to claim 4, characterized in that In step 3), the vacuum drying is performed at 333 K for 6 h.
8. The method according to claim 4, characterized in that In step 4), the volume ratio of deionized water to toluene is 1:2.