Silver nanoclusters and application thereof in oxidation of styrene and epoxy addition reaction with co2

Abstract

The application discloses silver nanoclusters and application of the silver nanoclusters in an oxidation styrene and CO2 ring-opening addition reaction. 14 (SPh 3.5 (CF3)2) 12 (DPPF)3, wherein SPh 3.5 (CF3)2=3.5-bis(trifluoromethyl)benzenethiol, DPPF=1,1-bis(diphenylphosphino)ferrocene. The synthesis method of the silver nanoclusters is simple, the condition is mild, the operation step is simple, the synthesized silver nanoclusters have high stability and high yield, and the silver nanoclusters have excellent catalytic performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanosynthesis, and particularly relates to a silver nanocluster and application of the silver nanocluster in an oxidation styrene and CO2 epoxide addition reaction. BACKGROUND

[0002] Ultra-small metal nanoclusters are a kind of metal core size of 1-2 nanometer nanoparticles, and the metal core (composed of several to hundreds of metal atoms) is protected by an organic ligand shell (sulfate, phosphine, alkyne, etc.), which is different from traditional large-particle metal particles. The size is easy to control, and has similar molecular properties (photoluminescence and magnetism, etc.) which make metal nanoclusters have potential application prospects in catalysis and biomedicine. Zhu's group reported Ag 62 S 12 Silver clusters are relatively Ag 62 S 13 Silver cluster photoluminescence occurs quenching (10.1021 / ja506773d); Zang's group reported that Ag 28 Nanoclusters can realize room temperature luminescence due to structural rigidity (10.1002 / anie.202004268); Wang's group reported using Ag 21 High yield and rapid catalysis of p-nitrophenol from p-nitrobenzene (10.1002 / anie.202116965). However, silver nanoclusters are easily oxidized by air, and have problems of low stability and yield, which makes it difficult to utilize its own properties. Therefore, developing a silver cluster with good stability and high yield has become a problem to be solved by researchers.

[0003] With the development of science and technology, CO2 is discharged in large quantities, and the global greenhouse effect is becoming more and more serious. People have a strong interest in the capture and utilization of CO2, and hope to convert CO2 into higher value chemical products. The synthesis of cyclic carbonates from epoxides and carbon dioxide has 100% atom economy, and is a very promising reaction. Shen's group reported that PtAg9 was used to catalyze the oxidation of styrene and CO2 with good results, with a yield of 70% (10.1039 / D3CP02736H). ZHU's group reported the use of different doping degrees of (AuAg) 21 Catalyze the oxidation of styrene and CO2, and find that when the number of doped silver is large, the catalytic yield increases, and the best yield is about 80% (10.1002 / anie.202100071). Metal nanoclusters are potential catalysts due to their precise structure. SUMMARY

[0004] In order to overcome the deficiencies of the prior art, the present application provides a silver nanocluster and its application in the epoxidation reaction of styrene oxide and CO2. The synthesis method of the silver nanocluster is simple, the conditions are mild, the operation steps are simple, the synthesized silver nanocluster has high stability and high yield, and at the same time has excellent catalytic performance.

[0005] The silver nanocluster of the present application has a molecular formula of Ag 14 (SPh 3.5 (CF3)2) 12 (DPPF)3, wherein SPh 3.5 (CF3)2=3.5-bis(trifluoromethyl)benzenethiol, DPPF=1,1-bis(diphenylphosphino)ferrocene.

[0006] The silver nanocluster of the present application is synthesized by a one-pot strategy, comprising the following steps:

[0007] Step 1: add a silver source to a 100 mL round-bottom flask containing 10 mL of methanol, stir for five minutes, then add 3.5-bis(trifluoromethyl)benzenethiol, stir at room temperature to obtain a white turbid solution; after ten minutes, add 1,1-bis(diphenylphosphino)ferrocene, at the same time add 15 mL of chloroform and 10 mL of ethanol, and after twenty-five minutes, add a reducing agent to the system, and after 20 hours, the reaction solution becomes black purple;

[0008] Step 2: centrifuge the black purple reaction solution obtained in step 1 to remove the insoluble matter, and after rotary evaporation treatment of the organic phase, dissolve it with a small amount of dichloromethane and extract it with a large amount of n-hexane solvent to obtain purple Ag 14 (SPh 3.5 (CF3)2) 12 (DPPF)3 nanocluster.

[0009] In step 1, the silver source is silver nitrate; the reducing agent is NaBH4. The molar ratio of the silver source, 3.5-bis(trifluoromethyl)benzenethiol, 1,1-bis(diphenylphosphino)ferrocene, and the reducing agent is 37:30:9:95.

[0010] The application of the silver nanocluster of the present application is used as a catalyst in the epoxidation reaction of styrene oxide and CO2.

[0011] Specifically, 2 mg of the silver metal nanocluster is added to 5 mL of dichloromethane solution, 100 mg of commercially purchased activated carbon is added, stirred for 3 hours, and then the mixture is centrifuged to obtain a precipitate; the precipitate is dried at room temperature for 5 hours to obtain a supported silver nanocluster catalyst, which is abbreviated as Ag 14 @AC (AC = activated carbon).

[0012] The specific steps of the catalytic reaction include:

[0013] Oxidation of styrene (0.307 mmol, 35 μL) was added under solvent-free conditions, 10 mg of tetrabutylammonium bromide and 100 mg of Ag 14 @AC catalyst, tied with a CO2 balloon at the bottle mouth, stirred at 75°C for 20 hours; at the end of the reaction, ethyl acetate was added to extract the organic matter, and the catalyst was removed by centrifugation to obtain the product.

[0014] The synthesis route is as shown below:

[0015]

[0016] Compared with the prior art, the beneficial effects of the present application include:

[0017] 1. The present application provides a preparation method of novel silver nanoclusters, which has mild synthesis conditions, simple operation steps, convenient separation method and high yield, and can realize large-scale synthesis of kilograms; the experimental conditions are stable and easy to repeat.

[0018] 2. The silver nanoclusters prepared by the present application have high stability and high catalytic performance, providing potential prospects for subsequent applications.

[0019] 3. The silver nanoclusters prepared by the present application can realize the conversion of CO2 into high-value chemicals, effectively catalyze the epoxidation reaction of oxidation of styrene and CO2, and have high catalytic efficiency in the field of metal clusters, which can reach 88%.

[0020] 4. The silver nanoclusters prepared by the present application catalyze the epoxidation reaction of oxidation of styrene and CO2, and the catalyst has an accurate atomic structure, which can provide a structural model guide for studying the catalytic mechanism of the catalyst.

[0021] 5. The catalyst is a new catalyst and the preparation process is simple, without the need for high-temperature preparation. DETAILED DESCRIPTION

[0022] Figure 1 The ultraviolet peak of the silver nanoclusters prepared by the present application is 526 nanometers.

[0023] Figure 2 The mass spectrum characterization diagram of the silver nanoclusters prepared by the present application.

[0024] Figure 3 The single crystal structure diagram of the silver nanoclusters prepared by the present application.

[0025] Figure 4 The normal temperature stability diagram of the silver nanoclusters prepared by the present application.

[0026] Figure 5 The Ag 14Figure 1. Gas phase yield plot of the epoxidation of styrene with CO2 catalyzed by AC catalyst. DETAILED DESCRIPTION

[0027] The technical solutions of the present application are further analyzed and described below through specific examples.

[0028] Example 1: Ag 14 (SPh 3.5 (CF3)2) 12 Synthesis of (DPPF)3nanocluster

[0029] AgNO3(30 mg, 0.177 mmol) was added to 10 mL of methanol solvent at room temperature, and after stirring for 5 min, 3.5-bis(trifluoromethyl)benzenethiol was added, and after stirring for another 5 min, 1,1-bis(diphenylphosphino)ferrocene (24.9 mg, 0.045 mmol) was added to the above solution, and the color of the solution was yellow. Then, 15 mL of a mixed solution of chloroform and ethanol was added, and after stirring for 15 min, 2 mL of NaBH4 ethanol solution (0.474 mmol) was added dropwise to the reaction solution, and the color of the reaction solution changed from yellow to orange and finally to black. After stirring for 20 h, the insoluble matter was removed by centrifugation, and a small amount of dichloromethane was used to dissolve the insoluble matter and a large amount of n-hexane was added to extract the insoluble matter, thereby obtaining Ag 14 (SPh 3.5 (CF3)2) 12 (DPPF)3nanocluster.

[0030] Example 2: Ag 14 (SPh 3.5 (CF3)2) 12 Loading of (DPPF)3nanocluster

[0031] 2 mg of Ag 14 (SPh 3.5 (CF3)2) 12 (DPPF)3nanocluster was added to 5 mL of CH2Cl2, and then 100 mg of AC was added to the above solution and stirred at room temperature for 3 h. After centrifugation and drying at room temperature for 5 h, a silver catalyst with a loading of 2% was obtained, which was referred to as Ag 14 AC (AC = activated carbon).

[0032] Example 3: Epoxidation of styrene with CO2

[0033] One 10 mL Schlenk tube was selected, and under solvent-free conditions, 0.307 mmol of styrene oxide, 10 mg of tetrabutylammonium bromide, and 100 mg of the catalyst Ag 14AC, the Schlenk tube was sealed with rubber stopper and evacuated, and was tied with CO2 balloon, and the reaction was stirred at 75°C for 20 hours; at the end of the reaction, the balloon was removed and 3 mL of ethyl acetate was added to extract the organic matter, and then 42 μL of propyl benzene was added as an internal standard (the ratio of the gas phase peak area of the equal-molar product phenylethylene carbonate and the internal standard propyl benzene was 1.86), the catalyst was removed by centrifugation to obtain the organic matter, and the yield was analyzed by gas chromatography (GC), and the yield was 88%.

[0034] Example 4: Catalytic reaction of epoxy addition of styrene oxide and CO2

[0035] One 10 mL Schlenk tube was selected, and styrene oxide (0.307 mmol, 35 μL), 10 mg of tetrabutylammonium bromide, and 100 mg of catalyst Ag 14 AC, the Schlenk tube was sealed with rubber stopper and evacuated, and was tied with CO2 balloon, and the reaction was stirred at 75°C for 20 hours; at the end of the reaction, the balloon was removed and 3 mL of ethyl acetate was added to extract the organic matter, and then 42 μL of propyl benzene was added as an internal standard (the ratio of the gas phase peak area of the equal-molar product phenylethylene carbonate and the internal standard propyl benzene was 1.86), the catalyst was removed by centrifugation to obtain the organic matter, and the yield was analyzed by gas chromatography (GC), and the yield was 88%.

[0036] Example 5: Catalytic reaction of epoxy addition of styrene oxide and CO2 (reaction time 12 h)

[0037] One 10 mL Schlenk tube was selected, and styrene oxide (0.307 mmol, 35 μL), 10 mg of tetrabutylammonium bromide, and 100 mg of catalyst Ag 14 AC, the Schlenk tube was sealed with rubber stopper and evacuated, and was tied with CO2 balloon, and the reaction was stirred at 75°C for 20 hours; at the end of the reaction, the balloon was removed and 3 mL of ethyl acetate was added to extract the organic matter, and then 42 μL of propyl benzene was added as an internal standard (the ratio of the gas phase peak area of the equal-molar product phenylethylene carbonate and the internal standard propyl benzene was 1.86), the catalyst was removed by centrifugation to obtain the organic matter, and the yield was analyzed by gas chromatography (GC), and the yield was 88%.

[0038] Example 6: Catalytic reaction of epoxy addition of styrene oxide and CO2 (dichloromethane solvent)

[0039] One 10 mL Schlenk tube was selected, and styrene oxide (0.307 mmol, 35 μL), 10 mg of tetrabutylammonium bromide, and 100 mg of catalyst Ag 14AC, the Schlenk tube was sealed with rubber stopper and evacuated, CO2 balloon was tied, the reaction was stirred at 75 °C for 20 hours; at the end of the reaction, the balloon was removed and 3 mL of ethyl acetate was added to extract the organic matter, then 42 μL of propyl benzene was added as an internal standard (the ratio of gas phase peak area of equal molar product phenyl styrene carbonate and internal standard propyl benzene was 1.86), the catalyst was removed by centrifugation to obtain the organic matter, the yield was analyzed by gas chromatography (GC), the yield was 6%.

[0040] Example 7: Catalytic reaction of epoxy addition of styrene oxide with CO2 (different temperatures)

[0041] Four 10 mL Schlenk tubes were selected, styrene oxide (0.307 mmol, 35 μL), 10 mg of tetrabutylammonium bromide and 100 mg of catalyst Ag 14 AC, the Schlenk tube was sealed with rubber stopper and evacuated, CO2 balloon was tied, the reaction was stirred at 75 °C for 20 hours; at the end of the reaction, the balloon was removed and 3 mL of ethyl acetate was added to extract the organic matter, then 42 μL of propyl benzene was added as an internal standard (the ratio of gas phase peak area of equal molar product phenyl styrene carbonate and internal standard propyl benzene was 1.86), the catalyst was removed by centrifugation to obtain the organic matter, the yield was analyzed by gas chromatography (GC), the yield was 6%.

[0042] Example 8: Catalytic reaction of epoxy addition of styrene oxide with CO2 (50 mg of catalyst Ag 14 AC)

[0043] One 10 mL Schlenk tube was selected, styrene oxide (0.307 mmol, 35 μL), 10 mg of tetrabutylammonium bromide and 50 mg of catalyst Ag 14 AC, the Schlenk tube was sealed with rubber stopper and evacuated, CO2 balloon was tied, the reaction was stirred at 75 °C for 20 hours; at the end of the reaction, the balloon was removed and 3 mL of ethyl acetate was added to extract the organic matter, then 42 μL of propyl benzene was added as an internal standard (the ratio of gas phase peak area of equal molar product phenyl styrene carbonate and internal standard propyl benzene was 1.86), the catalyst was removed by centrifugation to obtain the organic matter, the yield was analyzed by gas chromatography (GC), the yield was 6%.

[0044] Example 9: Catalytic reaction of epoxy addition of styrene oxide with CO2 (catalyst without silver clusters)

[0045] One 10 mL Schlenk tube was selected, and under solvent-free conditions, styrene oxide (0.307 mmol, 35 μL), 10 mg of tetrabutylammonium bromide, and 100 mg of activated carbon without silver clusters were added, the Schlenk tube was sealed with a rubber plug and evacuated, a CO2 balloon was attached, and the reaction was stirred at 75 °C for 20 hours; at the end of the reaction, the balloon was removed and 3 mL of ethyl acetate was added to extract the organics, then 42 μL of propylbenzene was added as an internal standard (equimolar product phenyl styrene carbonate and internal standard propylbenzene gas phase peak area ratio 1.86), the catalyst was removed by centrifugation to obtain the organics, and the yield was analyzed by gas chromatography (GC), with a yield of 5%.

Claims

1. A silver nanocluster, characterized in that: The molecular formula of the silver nanoclusters is Ag. 14 (SPh 3.5 (CF3)2) 12 (DPPF)3, where SPh 3.5 (CF3)2=3,5-bis(trifluoromethyl)benzylthiophenol, DPPF=1,1-bis(diphenylphosphine)ferrocene.

2. The method for preparing the silver nanoclusters according to claim 1, characterized in that... Includes the following steps: Step 1: Add the silver source to methanol, stir and disperse evenly, then add 3,5-bis(trifluoromethyl)benzylthiophenol, stir at room temperature to obtain a white turbid liquid; then add 1,1-bis(diphenylphosphine)ferrocene to the system, along with chloroform and ethanol, and then add a reducing agent to the system. After 20 hours, the reaction solution turns blackish-purple. Step 2: Centrifuge the dark purple reaction solution obtained in Step 1 to remove insoluble matter. After rotary evaporation of the organic phase, dissolve it in dichloromethane and extract it with n-hexane solvent to obtain purple Ag. 14 (SPh 3.5 (CF3)2) 12 (DPPF)3 nanoclusters.

3. The preparation method according to claim 2, characterized in that: In step 1, the silver source is silver nitrate; the reducing agent is NaBH4.

4. The preparation method according to claim 2, characterized in that: In step 1, the molar ratio of silver source, 3,5-bis(trifluoromethyl)benzylthiophenol, 1,1-bis(diphenylphosphine)ferrocene and reducing agent is 37:30:9:

95.

5. The application of the silver nanoclusters according to claim 1, characterized in that: The silver nanoclusters were loaded onto activated carbon and applied to the catalytic reaction of styrene oxidation and CO2 epoxy addition. include: Add 2 mg of silver metal nanoclusters to 5 mL of dichloromethane solution, then add 100 mg of activated carbon, stir for 3 hours, and centrifuge the mixture to obtain the precipitate. The precipitate was dried at room temperature for 5 hours to obtain the supported silver nanocluster catalyst, abbreviated as Ag. 14 @AC; Styrene oxide, tetrabutylammonium bromide, and Ag were added separately under solvent-free conditions. 14 @AC catalyst, with CO2 balloon attached to the bottle mouth, to carry out epoxy addition catalytic reaction; at the end of the reaction, ethyl acetate is added to extract the organic matter, and the catalyst is removed by centrifugation to obtain the product; The synthesis route is shown below: 。 6. The application according to claim 5, characterized in that: The reaction temperature for the epoxy addition catalytic reaction was 75℃, and the reaction time was 20h.

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