A supported nanocluster catalyst and its application in catalyzing the hydrolysis of silane

Abstract

The present invention discloses a supported nanocluster catalyst and its application in catalyzing the hydrolysis of silanes. The molecular formula of the supported nanocluster catalyst is: Pd3 / MIL-125-NH2, which uses MIL-125-NH2 as a carrier and [Pd3Cl(PPh2)2(PPh3)3] + [SbF6] ‑ The nanoclusters are combined with the MIL-125-NH2 carrier to form a Pd3 / MIL-125-NH2 nanocomposite. The Pd3 / MIL-125-NH2 catalyst of the present invention can catalyze the hydrolysis reaction of silanes under mild conditions. At the same time, the catalyst can be recycled at least three times, with no obvious decrease in activity and a wide substrate generality, showing good practicality.

Description

Technical Field

[0001] The present invention relates to a supported nano - cluster catalyst and its application in catalyzing the hydrolysis of silanes. Background Art

[0002] Silanols are very important as versatile building blocks in organic synthesis and have been widely used as synthetic intermediates for drugs and bioactive molecules. Additionally, silanols can act as hydrogen - bond and anion - binding catalysts and monomers for silicone polymers. The wide application of silanols emphasizes the importance of their synthetic methods. The method using alkali metals with co - oxidants such as dioxygen or hydrogen peroxide is well - established. However, this method may suffer from base - catalyzed rearrangement, resulting in low selectivity. In the past few decades, many methods relying on strong oxidants, such as permanganate, peracid, dioxirane, silver nitrate, osmium tetroxide, etc., have also been studied for the synthesis of silanols. For example, in 2014, Wai Yip Fan et al. used a homogeneous silver nitrate catalyst for the clean hydrolysis oxidation of organosilanes and water to hydrogen and organosilanols. This readily available inorganic salt can not only act as a scalable catalyst with extremely high activity and excellent stability, but also is a simple, convenient and cost - effective catalyst (RSC Adv. 2014, 4, 37645 - 37648). However, the above - mentioned methods require a certain stoichiometry of oxidants, which means a large amount of waste will be generated. In 2019, Chaoqun Li et al. achieved the efficient oxidation of organosilanes to silanols with H2O2 under neutral conditions by utilizing the excellent catalytic activity of electron - rich manganese complexes. In a short reaction time, a series of hydrosilanes and dihydrosilanes were respectively oxidized to silanol and silanediol with excellent yields and no waste by - products were generated. However, this reaction requires a relatively high catalyst loading (Angew. Chem., Int. Ed. 2019, 58, 6380 - 6384). Summary of the Invention

[0003] Aiming at the deficiencies of the above - mentioned prior art, the present invention provides a supported nano - cluster catalyst and its application in catalyzing the hydrolysis of silanes. The supported nano - cluster catalyst of the present invention can efficiently catalyze the hydrolysis reaction of silanes under relatively mild reaction conditions. The catalyst has a low loading, can be recycled multiple times, its activity does not decrease significantly, and it has a wide substrate generality.

[0004] The supported nano - cluster catalyst of the present invention has the molecular formula: [Pd3Cl(PPh2)2(PPh3)3] + [SbF6] - / MIL-125-NH2, abbreviated as Pd3 / MIL-125-NH2, is a nanocomposite material in which Pd3 nanoclusters are combined with MIL-125-NH2 using MIL-125-NH2 as a carrier.

[0005] The supported nanocluster catalyst of the present invention is prepared by a method including the following steps:

[0006] Step 1: First, synthesize Pd3 nanoclusters;

[0007] Step 2: Synthesize the carrier MIL-125-NH2;

[0008] Step 3: Ultrasonically treat MIL-125-NH2 to uniformly disperse it in a dichloromethane solution to obtain suspension A; dropwise add a dichloromethane solution containing Pd3 nanoclusters to suspension A, stir for 1 hour, separate to obtain a solid, wash and dry the solid, and recover the Pd3 / MIL-125-NH2 nanocomposite material.

[0009] Specifically:

[0010] In Step 1, dissolve PdCl2 (1.42 g, 8 mmol) in an aqueous HCl solution (16 mmol, 2 equiv / pd), and then dilute the solution to 10 mL. Add aliquots of the above solution (0.6 mL, 0.48 mmol) to 10 mL of THF, and then add triphenylphosphine (0.313 g, 1.2 mmol). After vigorously stirring for 8 min, add NaBH4 (0.08 g, 2.1 mmol, dissolved in 5 mL of ethanol), and keep the reaction solution under vigorous stirring for 60 min. Then centrifuge to remove the undissolved (excess) triphenylphosphine, and vacuum evaporate the remaining solution to dryness on a rotary evaporator. To remove sodium salts, redissolve the solid in 10 mL of dichloromethane, wash with water, and then evaporate to dryness again. Extract the remaining solid several times with ethanol, and rotary evaporate the obtained ethanol solution to dryness. Dissolve the solid in the minimum amount of ethanol, and drop the solution into hexane. Centrifuge to collect the precipitate to obtain the crude cluster product. For crystallization, dissolve the Pd3 clusters in ethanol (1.5 - 2 mL), add NaSbF6 to the solution, and then centrifuge. Collect the solid and redissolve it in dichloromethane, and then centrifuge again. Finally, crystallize the solution by layering with n-hexane at room temperature for 2 days.

[0011] In Step 2, add 50 mL of N,N-dimethylformamide (DMF) and 10 mL of methanol, a total of 60 mL of solvent, into a 100 mL hydrothermal reactor. Weigh 3.75 g of aminophthalic acid and dissolve it in the above solution. Then add 3.75 mL of titanium isopropoxide. Tighten the hydrothermal reactor and place it in an oven. Keep it at 150 °C for 16 h. After the reaction is completed, let it stand and cool to room temperature. Carefully open the hydrothermal reactor, take out the pale yellow solid inside, wash it with methanol 2 - 3 times to remove the unreacted raw materials. Then place the product in an oven, set the temperature to 60 °C and dry it overnight to obtain the support MIL-125-NH2.

[0012] In Step 3, add 10 mL of CH2Cl2 solvent into a 100 mL reaction flask. Then weigh 500 mg of MIL-125-NH2 and pour it into the reaction flask. Ultrasonic continuously for several 10 minutes, and place it on a stirrer and set a relatively high rotation speed for stirring. Weigh 1 mg of Pd3 nanoclusters, dissolve them in 5 mL of CH2Cl2, that is, the concentration is 0.2 mg / mL, and drop it into the above stirred reaction flask. After continuous stirring for 1 hour, centrifuge the solid and wash it with CH2Cl2 solution 2 - 3 times. It is found that the supernatant has no color, indicating that the loading performance of Pd3 clusters on MIL-125-NH2 is good. Finally, put the obtained solid catalyst into an oven set at 60 °C for about 3 hours to dry, and obtain the Pd3 / MIL-125-NH2 catalyst. Through ICP calculation, the Pd loading amount of the catalyst is 0.01 wt%.

[0013] The application of the supported nanocluster catalyst of the present invention is to use the supported nanoclusters as a catalyst to catalyze the hydrolysis reaction of silanes.

[0014] Specifically, add 0.5 mmol of silane, 30 - 50 mg of MIL-125-NH2 catalyst, and 2 mL of tetrahydrofuran into a 10 mL Schlenk reaction flask in sequence. Stir and react at room temperature in an air atmosphere for 15 - 20 min. After the reaction is completed, wait for the temperature of the reaction solution to cool to room temperature, and separate the solid and liquid by centrifugation.

[0015] The tetrahydrofuran is analytical pure tetrahydrofuran, and the moisture absorbed by the reaction environment can meet the needs of this reaction.

[0016] The silanes include triethylsilane, tert-butyldimethylsilane, triisopropylsilane, diphenylsilane, etc.

[0017] The supported nanocluster catalyst Pd3 / MIL-125-NH2 of the present invention, as a catalyst for the hydrolysis reaction of silane, has good catalytic activity and stability. The actual metal content of this catalyst is low, and the reaction temperature has reactivity for the hydrolysis reaction of silane at room temperature and within the range of 30 mg - 50 mg of the catalyst dosage. Moreover, this catalyst also has good catalytic activity for silanes with different substituents.

[0018] The beneficial effects of the present invention are reflected in:

[0019] 1. The material of the present invention is simple to synthesize and prepare, and has good catalytic material properties.

[0020] 2. The material of the present invention, as a catalyst for the hydrolysis reaction of silane, can achieve the catalytic reaction within a certain range of reaction conditions, and after at least three cycles of use, the catalytic activity basically does not change significantly, and the substrate universality is relatively wide. Description of the Drawings

[0021] Figure 1 MS and XPS diagrams of Pd3 nanoclusters.

[0022] Figure 2 Ultraviolet spectrum and crystal structure of Pd3 nanoclusters.

[0023] Figure 3 TEM diagram of Pd3 / MIL-125-NH2.

[0024] Figure 4 XRD diagrams of MIL-125-NH2 and Pd3 / MIL-125-NH2. Detailed Embodiments

[0025] The technical solutions of the present invention will be further elaborated below in combination with specific embodiments.

[0026] Example 1: Preparation of Pd3 Nanoclusters

[0027] PdCl2 (1.42 g, 8 mmol) was dissolved in aqueous HCl solution (16 mmol, 2 equiv / pd), and then the solution was diluted to 10 mL. An aliquot of the above solution (0.6 mL, 0.48 mmol) was added to 10 mL of THF, and then triphenylphosphine (0.313 g, 1.2 mmol) was added. After stirring vigorously for 8 min, NaBH4 (0.08 g, 2.1 mmol, dissolved in 5 mL of ethanol) was added, and the reaction solution was kept under vigorous stirring for 60 min. Then, centrifugation was carried out to remove the undissolved (excess) triphenylphosphine, and the remaining solution was evaporated to dryness under vacuum on a rotary evaporator. To remove the sodium salt, the solid was redissolved in 10 mL of dichloromethane, washed with water, and then evaporated to dryness again. The remaining solid was extracted with ethanol several times, and the obtained ethanol solution was evaporated to dryness by rotary evaporation. The solid was dissolved in the minimum amount of ethanol, and the solution was dropped into hexane. The precipitate was collected by centrifugation to obtain the crude cluster product. For crystallization, the Pd3 cluster was dissolved in ethanol (1.5 - 2 mL), and after 200 mg of NaSbF6 was dissolved in methanol, it was added to the above ethanol solution, and then centrifuged. The solid was collected and redissolved in dichloromethane, and centrifuged again. Finally, the solution was crystallized by layering with n - hexane at room temperature for 2 days to obtain the product [Pd3Cl(PPh2)2(PPh3)3] + [SbF6] - nanoclusters.

[0028] Example 2: Preparation of the support MIL - 125 - NH2

[0029] 50 mL of N,N - dimethylformamide (DMF) and 10 mL of methanol, a total of 60 mL of solvent, were added to a 100 mL hydrothermal reactor. 3.75 g of aminophthalic acid was weighed and dissolved in the above solution, and then 3.75 mL of titanium isopropoxide was added. The hydrothermal reactor was tightened and placed in an oven, and kept at 150 °C for 16 h. After the reaction was completed, it was allowed to stand and cool to room temperature. The hydrothermal reactor was carefully opened, and the pale yellow solid inside was taken out, washed repeatedly with methanol 2 - 3 times to remove the unreacted raw materials, and then the product was placed in an oven and set to dry overnight at 60 °C to obtain our support MIL - 125 - NH2.

[0030] Example 3: Preparation of Pd3 / MIL - 125 - NH2

[0031] Add 10 mL of CH2Cl2 solvent to a 100 mL reaction flask, then weigh 500 mg of MIL-125-NH2 and pour it into the reaction flask. Sonicate continuously for several 10 minutes, place it on a stirrer and set a relatively high rotation speed for stirring; then weigh 1 mg of Pd3 nanoclusters, dissolve them in 5 mL of CH2Cl2, that is, the concentration is 0.2 mg / mL, and drip it into the above-mentioned stirred reaction flask. After continuous stirring for 1 hour, centrifuge the solid and wash it 2 - 3 times with CH2Cl2 solution. It is found that the supernatant has no color, indicating that the loading performance of Pd3 clusters on MIL-125-NH2 is good. Finally, put the obtained solid catalyst into an oven set at 60 °C for about 3 hours to dry, and obtain the Pd3 / MIL-125-NH2 catalyst. The Pd loading of the catalyst is calculated by ICP to be 0.01 wt%.

[0032] Example 4: Hydrolysis reaction of silane catalyzed by MIL-125-NH2

[0033] Add 0.5 mmol of triethylsilane, 50 mg of MIL-125-NH2 catalyst, and 2 ml of tetrahydrofuran to a 10 mL Schlenk reaction flask in sequence. Stir and react at room temperature in an air atmosphere for 20 min. After the reaction is completed, wait for the temperature of the reaction solution to cool to room temperature, separate the solid and liquid by centrifugation (10000 rpm), and analyze the reaction solution by GC. The yield is 0%.

[0034] Example 5: Hydrolysis reaction of silane catalyzed by Pd3 / MIL-125-NH2 (different reaction times)

[0035] (1) Add 0.5 mmol of triethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst, and 2 ml of tetrahydrofuran to a 10 mL Schlenk reaction flask in sequence. Stir and react at room temperature in an air atmosphere for 20 min. After the reaction is completed, separate the solid and liquid by centrifugation (10000 rpm), and analyze the reaction solution by GC. The yield is 99.0%.

[0036] 1 H NMR (400 MHz, DMSO-d6) δ 0.86 (td, J = 7.9, 1.1 Hz, 9H), 0.41 (td, J = 8.4, 7.3 Hz, 6H). 13 C NMR (101 MHz, DMSO-d6) δ 7.29, 6.21.

[0037] (2) 0.5 mmol of triethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst and 2 ml of tetrahydrofuran were successively added to a 10 mL Schlenk reaction flask, and the mixture was stirred at room temperature in an air atmosphere for 1 min. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm), and the reaction solution was analyzed by GC with a yield of 7.0%.

[0038] (3) 0.5 mmol of triethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst and 2 ml of tetrahydrofuran were successively added to a 10 mL Schlenk reaction flask, and the mixture was stirred at room temperature in an air atmosphere for 3 min. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm), and the reaction solution was analyzed by GC with a yield of 11.5%.

[0039] (4) 0.5 mmol of triethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst and 2 ml of tetrahydrofuran were successively added to a 10 mL Schlenk reaction flask, and the mixture was stirred at room temperature in an air atmosphere for 7 min. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm), and the reaction solution was analyzed by GC with a yield of 39.9%.

[0040] (5) 0.5 mmol of triethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst and 2 ml of tetrahydrofuran were successively added to a 10 mL Schlenk reaction flask, and the mixture was stirred at room temperature in an air atmosphere for 11 min. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm), and the reaction solution was analyzed by GC with a yield of 63.2%.

[0041] (6) 0.5 mmol of triethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst and 2 ml of tetrahydrofuran were successively added to a 10 mL Schlenk reaction flask, and the mixture was stirred at room temperature in an air atmosphere for 15 min. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm), and the reaction solution was analyzed by GC with a yield of 95.0%.

[0042] (7) 0.5 mmol of triethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst and 2 ml of tetrahydrofuran were successively added to a 10 mL Schlenk reaction flask, and the mixture was stirred at room temperature in an air atmosphere for 18 min. After the reaction, when the temperature of the reaction solution was cooled to room temperature, the solid and liquid were separated by centrifugation (10000 rpm), and the reaction solution was analyzed by GC with a yield of 98.0%.

[0043] Example 6: Pd3 / MIL-125-NH2 Catalyzed Hydrolysis Reaction of Silane (Different Solvents)

[0044] 0.5 mmol of triethylsilane and 50 mg of Pd3 / MIL-125-NH2 catalyst were successively added to a 10 mL Schlenk reaction flask, followed by 2 mL of anhydrous tetrahydrofuran. The mixture was stirred at room temperature for 20 min under an air atmosphere. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm). The reaction solution was analyzed by GC, and the yield was 0%.

[0045] Example 7: Pd3 / MIL-125-NH2 Catalyzed Hydrolysis Reaction of Silane (Different Catalyst Dosages)

[0046] (1) 0.5 mmol of triethylsilane and 30 mg of Pd3 / MIL-125-NH2 catalyst were successively added to a 10 mL Schlenk reaction flask, followed by 2 mL of tetrahydrofuran. The mixture was stirred at room temperature for 20 min under an air atmosphere. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm). The reaction solution was analyzed by GC, and the yield was 71.8%.

[0047] (2) 0.5 mmol of triethylsilane and 40 mg of Pd3 / MIL-125-NH2 catalyst were successively added to a 10 mL Schlenk reaction flask, followed by 2 mL of tetrahydrofuran. The mixture was stirred at room temperature for 20 min under an air atmosphere. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm). The reaction solution was analyzed by GC, and the yield was 83.1%.

[0048] Based on the above examples, we selected the reaction conditions (0.5 mmol of triethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst, 2 mL of tetrahydrofuran, air atmosphere, reaction temperature of 30 °C, reaction time of 20 min) to test the stability of the Pd3 / MIL-125-NH2 catalyst for the hydrolysis reaction of silane. The reaction results are shown in the following examples.

[0049] Example 8: First Cycle of Pd3 / MIL-125-NH2 Catalyzed Hydrolysis Reaction of Silane

[0050] 0.5 mmol of triethylsilane and 50 mg of Pd3 / MIL-125-NH2 catalyst were successively added to a 10 mL Schlenk reaction flask, followed by 2 mL of tetrahydrofuran. The mixture was stirred at room temperature for 20 min under an air atmosphere. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm). The reaction solution was analyzed by GC, and the yield was 95.0%.

[0051] The recovered Pd3 / MIL-125-NH2 catalyst was washed three times with methanol and dried at 50 °C for 2 hours in a vacuum drying oven for the next cycle.

[0052] Example 9: Second cycle of the hydrolysis reaction of silane catalyzed by Pd3 / MIL-125-NH2

[0053] To a 10 mL Schlenk reaction flask, 0.5 mmol of triethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst, and 2 mL of tetrahydrofuran were added successively. The mixture was stirred at room temperature for 20 min in an air atmosphere. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm). The reaction solution was analyzed by GC, and the yield was 92.3%.

[0054] Example 10: Third cycle of the hydrolysis reaction of silane catalyzed by Pd3 / MIL-125-NH2

[0055] To a 10 mL Schlenk reaction flask, 0.5 mmol of triethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst, and 2 mL of tetrahydrofuran were added successively. The mixture was stirred at room temperature for 20 min in an air atmosphere. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm). The reaction solution was analyzed by GC, and the yield was 90.7%.

[0056] The following examples are the substrate expansion of the hydrolysis reaction of silane with the Pd3 / MIL-125-NH2 catalyst.

[0057] Example 11: Hydrolysis reaction of tert-butyldimethylsilane catalyzed by Pd3 / MIL-125-NH2

[0058] To a 10 mL Schlenk reaction flask, 0.5 mmol of tert-butyldimethylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst, and 2 mL of tetrahydrofuran were added successively. The mixture was stirred at room temperature for 25 min in an air atmosphere. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm). The reaction solution was analyzed by GC, and the yield was 92.9%.

[0059] 1 H NMR (400 MHz, DMSO-d6) δ0.80 (s, 9H), -0.08 (s, 6H). 13 C NMR (101MHz, DMSO-d6) δ 26.34, -2.67.

[0060] Example 12: Hydrolysis reaction of triisopropylsilanol catalyzed by Pd3 / MIL-125-NH2

[0061] 0.5 mmol of triisopropylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst and 2 ml of tetrahydrofuran were successively added to a 10 mL Schlenk reaction flask, and the mixture was stirred at room temperature in an air atmosphere for 20 min. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm), and the reaction solution was analyzed by GC with a yield of 94.5%.

[0062] 1 H NMR (400 MHz, DMSO-d6) δ 0.95 (d, J = 6.5 Hz, 18H). 13 C NMR (101MHz, DMSO-d6) δ 18.38, 12.60.

[0063] Example 13: Hydrolysis reaction of diphenylsilane catalyzed by Pd3 / MIL-125-NH2

[0064] 0.25 mmol of diphenylsilane, 50 mg of Pd3 / MIL-125-NH2 catalyst and 2 ml of tetrahydrofuran were successively added to a 10 mL Schlenk reaction flask, and the mixture was stirred at room temperature in an air atmosphere for 120 min. After the reaction, the solid and liquid were separated by centrifugation (10000 rpm), and the reaction solution was analyzed by GC with a yield of 98.1%.

[0065] 1 H NMR (400 MHz, DMSO-d6) δ 7.59-7.52 (m, 4H), 7.37-7.24 (m, 6H). 13 C NMR (101 MHz, DMSO-d6) δ 134.71-134.40 (m), 130.03 (d, J = 32.9 Hz), 128.05(d, J = 10.5 Hz).

Claims

1. Application of a supported nanocluster catalyst, characterized in that: Using the supported nanoclusters as a catalyst to catalyze the hydrolysis reaction of silane; the molecular formula of the supported nanocluster catalyst is [Pd3Cl(PPh2)2(PPh3)3] + [SbF6] - / MIL-125-NH2, abbreviated as Pd3 / MIL-125-NH2, uses MIL-125-NH2 as the carrier, and [Pd3Cl(PPh2)2(PPh3)3] + [SbF6] - The nanoclusters are combined with the MIL-125-NH2 carrier to form a Pd3 / MIL-125-NH2 nanocomposite; the loading amount of Pd in the supported nanocluster catalyst is 0.01 wt%.

2. The application according to claim 1, wherein The supported nanocluster catalyst is prepared by a method comprising the following steps: Step 1: First, synthesize Pd3 nanoclusters; Step 2: Synthesize the support MIL-125-NH2; Step 3: Ultrasonically treat MIL-125-NH2 to uniformly disperse it in a dichloromethane solution to obtain suspension A; dropwise add a dichloromethane solution containing Pd3 nanoclusters to suspension A, stir for 1 hour, separate to obtain a solid, wash and dry the solid, and recover the Pd3 / MIL-125-NH2 nanocomposite.

3. The application according to claim 1, characterized in that: The silane includes triethylsilane, tert-butyldimethylsilane, triisopropylsilane, diphenylsilane.

4. The application according to claim 1, characterized in that: Add 0.5 mmol of silane, 30 - 50 mg of Pd3 / MIL-125-NH2 catalyst, and 2 ml of tetrahydrofuran to a Schlenk reaction flask in sequence, stir and react at room temperature in an air atmosphere. After the reaction, cool the reaction solution to room temperature and centrifuge to separate the solid and liquid.

5. The application according to claim 4, characterized in that: The reaction time is 15 - 20 min.

Images