A method for catalyzing the reduction hydrogenation of alkynes using palladium nanowires

Abstract

The present invention discloses a method for catalyzing the reductive hydrogenation of aryl acetylenes using palladium nanowires. This method utilizes easily prepared, highly active palladium nanowires (PdNWs) as a catalyst to achieve the catalytic reductive hydrogenation of alkynes under mild conditions. This method utilizes the prepared palladium nanowires as a catalyst, sodium borohydride (NaBH4) as a reducing agent, and methanol as a reaction solvent to achieve the reductive hydrogenation of aryl alkynes at room temperature and pressure. After only 0.5 hours of reaction, the raw material is fully converted, with a yield of nearly 100%. The olefin to alkane ratio is 99:1, demonstrating extremely high selectivity. This method is simple to operate, operates under mild conditions, and can efficiently achieve the reductive hydrogenation of alkynes.

Description

Technical Field

[0001] The present invention relates to a green chemical synthesis method, in particular to the catalysis of the reduction hydrogenation reaction of aryl acetylene by using palladium nanowires under mild conditions, and belongs to the field of nano-organic catalysis. Background Art

[0002] Hydrogenation is a major research topic in fine chemicals, safety chemicals, petrochemicals, and coal chemical industries. In the synthesis of fine chemicals, compounds with various functional groups require clean H₂ as a hydrogen source for the selective reduction of these compounds to produce corresponding alkenes, alcohols, and amines. These products are key intermediates in the production of biological, pharmaceutical, and pesticide products. So, what's the simplest and fastest way to obtain carbon-carbon double-bonded alkenes and carbon-carbon single-bonded alkanes? The most common approach is reductive hydrogenation of alkynes. The hydrogenation of alkynes is the simplest and most direct method for constructing olefin and alkane bonds. With the continued research of scientific researchers, significant progress has been made in alkyne hydrogenation technology, making it one of the simplest and most direct methods for synthesizing alkenes and alkanes in both the laboratory and industry.

[0003] Although in recent decades, researchers have continuously explored new methods to prepare functionalized alkenes under mild conditions through cross-coupling reactions. However, in previous experiments on catalytic alkynes, most hydrogenation reactions required the use of large amounts of expensive metals as catalysts, or the addition of toxic additives to reduce the alkynes. This not only wastes resources but also causes significant environmental pollution, which is extremely inconsistent with my country's pursuit of green chemistry. Therefore, the preparation of more active catalysts has become a goal that researchers have strived for. With the continuous in-depth research in the field of nanomaterials, more and more researchers have discovered that nanomaterials have a loose and porous morphology compared to metal-structured catalysts, which can provide more active sites and open up a new direction for organic catalysis. Summary of the Invention

[0004] The technical problem solved by the present invention is to propose a method for catalyzing the reduction hydrogenation reaction of alkynes using a highly active nanocatalyst palladium nanowire. The method is not suitable for strong acids or bases, has mild conditions, can be carried out at room temperature and pressure, and can reduce the hydrogenated products in a green and efficient manner.

[0005] This method utilizes prepared palladium nanowires as a catalyst, sodium borohydride (NaBH4) as a reducing agent, and methanol as a reaction solvent to achieve the reductive hydrogenation of aryl alkynes at room temperature and pressure. Complete conversion of the starting material is achieved in just 0.5 hours, with a yield of nearly 100%. The olefin to alkane ratio is 99:1, demonstrating extremely high selectivity. This method is simple to operate, operates under mild conditions, and efficiently achieves the reductive hydrogenation of alkynes.

[0006] In order to solve the above technical problems, the technical solution proposed in the present invention is: a method for catalyzing the reduction hydrogenation reaction of aryl acetylene using palladium nanowires, the specific steps comprising:

[0007] Palladium nanowires were prepared as catalysts, sodium borohydride NaBH4 was used as a reducing agent, and methanol was used as a reaction solvent to catalyze the reductive hydrogenation reaction of aryl alkynes.

[0008] Using the prepared palladium nanowires as a catalyst, NaBH4 as a reducing agent, and methanol as a reaction solvent, the aryl alkyne of formula 1 can be reduced to olefins of formula 2 and alkanes of formula 3 under normal temperature and pressure conditions.

[0009] The specific reaction route is as follows:

[0010]

[0011] Wherein R is methyl, tert-butyl, halogen, phenylacetylene, polycyclic ring, heterocyclic ring or polyalkyne.

[0012] Preferably, the specific preparation steps of the palladium nanowires are as follows:

[0013] Step (1): 0.4 mL of a 0.1 mg / mL aqueous solution of sodium citrate (CA) and 23.32 mL of H2O were added to a 50 mL three-necked flask. After stirring for one minute, 4.68 mL of a 2.118 mg / mL aqueous solution of sodium chloropalladate (NaPdCl4) was added. After stirring for 10 minutes, 1.2 mL of a 3.783 mg / mL aqueous solution of NaBH4 was added. Finally, after stirring for 10 minutes, 3-5 μm palladium nanoparticles (PdNPs) were obtained.

[0014] Step (2): Place the silicon wafer 1cm 2 Wash with soapy water, ethanol, and pure water for 4 min each;

[0015] Step (3): The silicon wafer in step 2 was treated with a plasma cleaner for 10 min to obtain a hydrophilic surface, and then 1.5 mL of 3-aminopropyltriethoxysilane APTES solution was taken at 5 × 10 -3 The surface was immersed in M ​​for 30 min to make the surface functionalized with amines. The solution consisted of water and ethanol in equal volume ratios.

[0016] Step (4): After rinsing with pure water three times, the silicon wafer in step 3 was transferred to 1.5 mL of the 3-5 nm palladium seed solution in step 1 and soaked for 0.5 h to allow the palladium seeds to be adsorbed on the surface of the silicon wafer;

[0017] Step (5): The silicon wafer prepared in step 4 was rinsed three times with pure water to remove excess palladium seeds, and then placed in 1.5 mL of growth solution containing 2.0 × 10 -3M, sodium chloropalladate 2.4×10 -3 M and reducing agent L-ascorbic acid 4.3×10 -3 In the M solution, which consists of water and ethanol in a volume ratio of 1:2, after soaking for 0.5 hours, the wafer is covered with the desired palladium nanowires PdNWs;

[0018] Step (6): Place the silicon wafer in step 5 in ethanol for storage.

[0019] Preferably, the specific steps are as follows:

[0020] The prepared palladium nanowires, along with the silicon wafer and methanol solution, were placed in a glass vial. Ultrasonication was performed to dissociate the palladium nanowires in the reaction solvent. NaBH4 and 4-ethynylbiphenyl were then added. The vial was sealed with a rubber stopper and a deflated balloon inserted to maintain constant pressure. Stirring was performed at room temperature, and the reaction progress was monitored using a TLC plate. After the reaction was completed, water was added to quench the reaction. The organic phase was then washed with 3 × 5 mL of brine and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture was purified by column chromatography using pure n-hexane.

[0021] Preferably, the molar ratio of the aryl acetylene of formula 1 to the reducing agent NaBH4 is 1:3, and the molar ratio of the palladium nanowires to the aryl acetylene is 0.32:1.

[0022] Preferably, at room temperature and pressure, the conversion of the reaction substrate can be completed within 0.5 h of reaction.

[0023] Preferably, 0.32 mol% and 0.034 mg of the prepared palladium nanowires (PdNWs) are placed in a glass bottle together with a silicon wafer and 1.5 mL of methanol solution. The palladium nanowires are freed in the reaction solvent by ultrasound, followed by the addition of 11.32 mg (3 eq.) of NaBH4 and 17.8 mg (0.1 mmol) of 4-ethynylbiphenyl. The bottle mouth is stoppered with a rubber stopper and a deflated balloon is inserted to maintain a constant pressure in the system. Stirring is performed at room temperature, and the reaction progress is monitored by TLC. After 0.5 h of reaction, the reaction is quenched with water, and the organic phase is washed with 3 × 5 mL of brine and dried over anhydrous MgSO4. After vacuum concentration, the mixture is purified by column chromatography using pure n-hexane. The HPLC yield is greater than 99%, and the olefin to alkane ratio is 99:1. The specific route is as follows:

[0024]

[0025] Preferably, 0.32 mol% and 0.068 mg of the prepared palladium nanowires (PdNWs) are placed in a glass bottle together with a silicon wafer and 1 mL of methanol solution. The palladium nanowires are freed in the reaction solvent by ultrasound, followed by the addition of 22.72 mg (3 eq.) of NaBH4 and 30.63 mg (0.2 mmol) of 3-ethynylquinoline. The bottle mouth is stoppered with a rubber stopper and a deflated balloon is inserted to maintain a constant pressure in the system. Stirring is performed at room temperature, and the reaction progress is monitored by TLC plates. After 0.5 h of reaction, water is added for quenching, and the organic phase is then washed with 3×5 mL of brine and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture is purified by column chromatography using ethyl acetate and n-hexane as the mobile phase in a volume ratio of 1:5. The HPLC yield is greater than 99%, and the olefin to alkane ratio is 95:5, which has good selectivity. The specific route is as follows:

[0026]

[0027] Beneficial effects of the present invention:

[0028] (1) The method of the present invention is simple to operate. It directly catalyzes the reductive hydrogenation of aryl alkynes at room temperature and pressure using palladium nanowires as a catalyst, sodium borohydride (NaBH4) as a reducing agent, and methanol as a reaction solvent. This method can yield 99% of the alkyne hydrogenation product in as little as 0.5 h.

[0029] (2) The present invention ultimately selects an aryl acetylene of formula 1, wherein R is a methyl group, a tert-butyl group, a halogen group, a phenylacetylene, a polycyclic ring, a heterocyclic ring, or a polyalkyne, and catalyzes the reduction hydrogenation of the aryl alkyne with a yield of over 99%. The method of the present invention is applicable to a variety of alkyne substrates, including methyl, tert-butyl, a halogen group, a phenylacetylene, a polycyclic ring, a heterocyclic ring, or a polyalkyne, and can obtain the alkyne reduction hydrogenation product with excellent yield and high selectivity, and has good functional group tolerance.

[0030] (3) Adding too much or too little NaBH4 to the reaction is not conducive to the reaction and will also result in poor selectivity. The optimal molar ratio of aryl acetylene to reducing agent NaBH4 is 1:3.

[0031] Adding too much or too little palladium nanowires (PdNWs) to the reaction is not conducive to the reaction and will also result in poor selectivity. The optimal molar amount of palladium nanowires is 0.32 mol%.

[0032] 0.32 mol% (0.034 mg) of the prepared palladium nanowires (PdNWs) along with a silicon wafer were placed in a glass vial with 1.5 mL of ethanol, dimethyl sulfoxide, ethyl acetate, tetrahydrofuran, and dimethylformamide solutions, respectively. Ultrasonication was performed to dissociate the PdNWs in the reaction solvent. Then, 11.35 mg (3 eq.) of NaBH4 and 17.8 mg (0.1 mmol) of 4-ethynylbiphenyl were added. The vial was sealed with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature and monitored by TLC. After 0.5 h of reaction, the reaction was quenched with water. The organic phase was then washed with brine (3 × 5 mL) and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture was purified by column chromatography (pure n-hexane). The yields, calculated by HPLC, were 5%, 0%, 16%, 0%, and 4%, respectively, demonstrating the superior performance of methanol as the reaction solvent. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below in conjunction with the accompanying drawings:

[0034] Figure 1 This is a scanning electron microscope (SEM) image of the palladium nanowires in Example 1.

[0035] Figure 2 This is the NMR image of the reduction and hydrogenation reaction of 4-ethynylbiphenyl catalyzed by palladium nanowires, which proves the structure of the product.

[0036] Figure 3 The NMR image of the reductive hydrogenation reaction of 3-acetylenequinoline catalyzed by palladium nanowires confirms the structure of the product.

[0037] Figure 4 This is a TLC spot plate image of the reductive hydrogenation of 4-ethynylbiphenyl catalyzed by palladium nanowires.

[0038] Figure 5 This is the TLC spot chart of the reductive hydrogenation reaction of 3-ethynylquinoline on palladium nanowires. DETAILED DESCRIPTION

[0039] Example 1

[0040] Add 0.4 mL of sodium citrate (CA) aqueous solution (0.1 mg / mL) and 23.32 mL of H2O into a 50 mL three-necked flask, stir for one minute, then add 4.68 mL of NaPdCl4 aqueous solution (2.118 mg / mL), then stir for 10 minutes, add 1.2 mL of NaBH4 aqueous solution (3.783 mg / mL), and finally stir for 10 minutes to obtain 3-5 mn palladium nanoparticles (PdNPs).

[0041] The silicon wafer (about 1 cm 2) were cleaned with soapy water, ethanol, and pure water for 4 min respectively. Then, the surface was treated with a plasma cleaner for 10 min to obtain a hydrophilic surface. Then, 1.5 mL of 3-aminopropyltriethoxysilane (APTES) solution (5 × 10 -3 M) for 30 minutes to make the surface functionalized with amines. The solution consists of water and ethanol in equal volume ratios. After rinsing with pure water three times, the silicon wafer is transferred to 1.5 mL of palladium seed (3-5 nm) solution and soaked for 0.5 hours to allow the palladium seeds to adsorb on the silicon wafer surface. The silicon wafer is rinsed with pure water three times to remove excess palladium seeds. It is then placed in 1.5 mL of growth solution containing a thiol ligand 4-mercaptobenzoic acid (2.0×10 -3 M), sodium chloropalladate (2.4×10 -3 M) and the reducing agent L-ascorbic acid (4.3×10 - 3 M) solution, which consists of water and ethanol in a volume ratio of 1:2. After soaking for 0.5 hours, the wafer is covered with the desired 262nm long palladium nanowires (PdNWs) and finally stored in ethanol until use.

[0042] Example 2

[0043] 0.32 mol% (0.034 mg) of the prepared palladium nanowires (PdNWs), along with a silicon wafer and 1.5 mL of methanol solution, were placed in a glass vial. Ultrasonication was used to dissociate the PdNWs from the reaction solvent. Then, 11.32 mg (3 eq.) of NaBH4 and 17.8 mg (0.1 mmol) of 4-ethynylbiphenyl were added. The vial was sealed with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature, and progress was monitored by TLC. After 0.5 h, the reaction was quenched with water. The organic phase was then washed with brine (3 × 5 mL) and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture was purified by column chromatography (pure n-hexane). The HPLC yield was greater than 99%, with an olefin to alkane ratio of 99:1.

[0044]

[0045] Example 3

[0046] 0.32 mol% (0.068 mg) of the prepared palladium nanowires (PdNWs), along with a silicon wafer and 1 mL of methanol solution, were placed in a glass vial. Ultrasonication was used to dissociate the PdNWs from the reaction solvent. 22.72 mg (3 eq.) of NaBH4 and 30.63 mg (0.2 mmol) of 3-ethynylquinoline were then added. The vial was sealed with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature, and progress was monitored by TLC. After 0.5 h, the reaction was quenched with water. The organic phase was then washed with brine (3 × 5 mL) and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture was purified by column chromatography using a mobile phase of ethyl acetate and n-hexane in a 1:5 volume ratio. The HPLC yield was greater than 99%, with an olefin to alkane ratio of 95:5.

[0047]

[0048] Example 4

[0049] 0.32 mol% (0.068 mg) of the prepared palladium nanowires (PdNWs), along with a silicon wafer and 1 mL of methanol solution, were placed in a glass vial. Ultrasonication was used to dissociate the PdNWs from the reaction solvent. 22.72 mg (3 eq.) of NaBH4 and 0.2 mmol of the other aryl-alkyne substrate were then added. The vial was sealed with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature, and progress was monitored by TLC. After 0.5 h of reaction, the reaction was quenched with water. The organic phase was then washed with brine (3 × 5 mL) and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture was purified by column chromatography (ethyl acetate / n-hexane). The yield was calculated by HPLC.

[0050]

[0051] The specific reaction route is as follows:

[0052] a:

[0053]

[0054] b:

[0055]

[0056] c:

[0057]

[0058] d:

[0059]

[0060] e:

[0061]

[0062] f:

[0063]

[0064] g:

[0065]

[0066] h:

[0067]

[0068] i:

[0069]

[0070] j:

[0071]

[0072] k:

[0073]

[0074] l:

[0075]

[0076] m:

[0077]

[0078] n:

[0079]

[0080] o:

[0081]

[0082] Comparative Example 1

[0083] 0.32 mol% (0.034 mg) of the prepared palladium nanowires (PdNWs), along with a silicon wafer and 1.5 mL of methanol solution, were placed in a glass vial. Ultrasonication was used to dissociate the PdNWs from the reaction solvent. Then, 3.78 (1 eq.), 7.57 (2 eq.), 11.35 (3 eq.), 15.14 (4 eq.), and 18.9 (5 eq.) of NaBH4 and 17.8 mg (0.1 mmol) of 4-ethynylbiphenyl were added. The vial was stoppered with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature and monitored by TLC. After 0.5 h of reaction, the reaction was quenched with water. The organic phase was then washed with brine (3 × 5 mL) and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture was purified by column chromatography (pure n-hexane). Yields calculated by HPLC were 95% (olefin to alkane ratio 81:19), greater than 99% (84:16), greater than 99% (99:1), 99% (94:6), and 49% (98:2), respectively. Adding too much or too little NaBH₄ to the reaction is detrimental to the reaction and results in poor selectivity. A molar ratio of aryl acetylene to reducing agent NaBH₄ of 1:3 is optimal.

[0084] Comparative Example 2

[0085] The prepared palladium nanowires (PdNWs) at concentrations of 0, 0.16 mol% (0.017 mg), 0.32 mol% (0.034 mg), 0.64 mol% (0.068 mg), and 0.96 mol% (0.102 mg) were placed in a glass vial along with a silicon wafer and 1.5 mL of methanol solution. Ultrasonication was performed to dissociate the PdNWs into the reaction solvent. 11.35 mg (3 eq.) of NaBH4 and 17.8 mg (0.1 mmol) of 4-ethynylbiphenyl were then added. The vial was stoppered with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature and monitored by TLC. After a 0.5 h reaction, the reaction was quenched with water. The organic phase was then washed with brine (3 × 5 mL) and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture was purified by column chromatography (pure n-hexane). Yields calculated by HPLC were 0%, 98% (olefin to alkane ratio 89:11), greater than 99% (99:1), greater than 99% (92:8), and greater than 99% (93:7), respectively. Adding too much or too little palladium nanowires (PdNWs) to the reaction was detrimental to the reaction and resulted in poor selectivity. The optimal molar content of the PdNWs catalyst was 0.32 mol%.

[0086] Comparative Example 3

[0087] 0.32 mol% (0.034 mg) of the prepared palladium nanowires (PdNWs) along with a silicon wafer were placed in a glass vial with 1.5 mL of ethanol, dimethyl sulfoxide, ethyl acetate, tetrahydrofuran, and dimethylformamide solutions, respectively. Ultrasonication was used to dissociate the PdNWs from the reaction solvent. Then, 11.35 mg (3 eq.) of NaBH4 and 17.8 mg (0.1 mmol) of 4-ethynylbiphenyl were added. The vial was sealed with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature, and the progress of the reaction was monitored by TLC. After 0.5 h of reaction, the reaction was quenched with water. The organic phase was then washed with brine (3 × 5 mL) and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture was purified by column chromatography (pure n-hexane). The yields, calculated by HPLC, were 5%, 0%, 16%, 0%, and 4%, respectively, demonstrating the superior performance of methanol as the reaction solvent.

[0088] Comparative Example 4

[0089] 0.32 mol% (0.068 mg) of the prepared palladium nanowires (PdNWs), along with a silicon wafer and 1 mL of methanol solution, were placed in a glass vial. Ultrasonication was used to dissociate the PdNWs into the reaction solvent. 22.72 mg (3 eq.) of NaBH4 and 0.2 mmol (35.6 mg) of diphenylacetylene were then added. The vial was stoppered with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature, and TLC plate analysis revealed that the reaction did not occur, and no target product was obtained.

[0090] Comparative Example 5

[0091] 0.32 mol% (0.068 mg) of the prepared palladium nanowires (PdNWs), along with a silicon wafer and 1 mL of methanol solution, were placed in a glass vial. Ultrasonication was used to dissociate the PdNWs into the reaction solvent. 22.72 mg (3 eq.) of NaBH4 and 0.2 mmol (32 mg) of methyl 4-ethynylbenzoate were then added. The vial was stoppered with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature while TLC plate analysis revealed that the reaction did not occur and no target product was obtained.

[0092] Comparative Example 6

[0093] 0.32 mol% (0.068 mg) of the prepared palladium nanowires (PdNWs), along with a silicon wafer and 1 mL of methanol solution, were placed in a glass vial. Ultrasonication was used to dissociate the PdNWs into the reaction solvent. 22.72 mg (3 eq.) of NaBH4 and 0.2 mmol (38.4 mg) of 1,3,5-tris(1-propyn-1-yl)benzene were then added. The vial was stoppered with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature and monitored by TLC. TLC analysis revealed that the reaction did not occur, and no target product was obtained.

Claims

1. A method for the reductive hydrogenation of arylacetylene using palladium nanowires, characterized in that: The specific steps include: The palladium nanowires are prepared as a catalyst, sodium borohydride NaBH4 is used as a reducing agent, and methanol is used as a reaction solvent to catalyze the reduction hydrogenation reaction of aryl alkynes. The prepared palladium nanowires are used as a catalyst, NaBH4 is used as a reducing agent, and methanol is used as a reaction solvent. At room temperature and pressure, the aryl alkynes of formula 1 can be reduced to alkenes of formula 2 and alkanes of formula 3. The specific reaction route is as follows: ; Wherein R is methyl, tert-butyl, halogen, or phenylacetylene.

2. The method for the reductive hydrogenation of alkynes catalyzed by palladium nanowires according to claim 1, wherein: The specific preparation steps of the palladium nanowires are as follows: Step (1): Add 0.4 mL of sodium citrate (CA) aqueous solution (0.1 mg / mL) and 23.32 mL of H2O into a 50 mL three-necked flask, stir for one minute, then add 4.68 mL of sodium chloropalladate (NaPdCl4) aqueous solution (2.118 mg / mL), then stir for 10 minutes, then add 1.2 mL of NaBH4 aqueous solution (3.783 mg / mL), and finally stir for 10 minutes to obtain 3-5 μm palladium nanoparticles (PdNPs); Step (2): Place the silicon wafer 1 cm 2 Wash with soapy water, ethanol, and pure water for 4 min each; Step (3): The silicon wafer prepared in step 2 was treated with a plasma cleaner for 10 min to obtain a hydrophilic surface, and then 1.5 mL of 3-aminopropyltriethoxysilane APTES solution (5 × 10 -3 The surface was functionalized with amines by immersion in M ​​solution consisting of water and ethanol in equal volume ratios for 30 min; Step (4): After rinsing with pure water three times, transfer the silicon wafer in step 3 to 1.5 mL of the palladium seed 3-5 nm solution in step 1 and soak for 0.5 h to allow the palladium seeds to be adsorbed on the surface of the silicon wafer; Step (5): Rinse the silicon wafer prepared in step 4 with pure water three times to remove excess palladium seeds, and then place it in 1.5 mL of growth solution containing 2.0×10 -3 M, sodium chloropalladate 2.4×10 -3 M and reducing agent L-ascorbic acid 4.3×10 -3 In the M solution, which consists of water and ethanol in a volume ratio of 1:2, after soaking for 0.5 h, the wafer is covered with the desired palladium nanowires PdNWs; Step (6): Place the silicon wafer prepared in step 5 in ethanol for storage.

3. The method for the reduction hydrogenation of arylacetylene using palladium nanowires as claimed in claim 1, wherein: The specific steps are as follows: The prepared palladium nanowires, along with the silicon wafer and methanol solution, were placed in a glass vial. Ultrasonication was used to dissociate the palladium nanowires in the reaction solvent. NaBH4 and the arylacetylene of Formula 1 were then added. The vial was sealed with a rubber stopper and a deflated balloon inserted to maintain constant pressure. Stirring was performed at room temperature, and the reaction progress was monitored using a TLC plate. After the reaction was completed, water was added to quench the reaction. The organic phase was then washed with 3 × 5 mL of brine and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture was purified by column chromatography using pure n-hexane.

4. The method for the reduction hydrogenation of arylacetylene using palladium nanowires as claimed in claim 1, wherein: The molar ratio of the aryl acetylene of formula 1 to the reducing agent NaBH4 is 1:3, and the molar ratio of the palladium nanowire to the aryl acetylene is 0.32:

1.

5. The method for the reduction hydrogenation of arylacetylene using palladium nanowires as claimed in claim 1, wherein: At room temperature and pressure, the conversion of the reaction substrate can be completed within 0.5 h.

6. A method for the reductive hydrogenation of arylacetylene using palladium nanowires, characterized in that: 0.32 mol% (0.034 mg) of the prepared palladium nanowires (PdNWs), along with a silicon wafer and 1.5 mL of methanol solution, were placed in a glass vial. Ultrasonication was used to free the PdNWs in the reaction solvent. Then, 11.32 mg (3 eq.) of NaBH4 and 17.8 mg (0.1 mmol) of 4-ethynylbiphenyl were added. The vial was stoppered with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature and monitored by TLC. After 0.5 h of reaction, the reaction was quenched with water. The organic phase was then washed with 3 × 5 mL of brine and dried over anhydrous MgSO4. After vacuum concentration, the mixture was purified by column chromatography using pure n-hexane. The HPLC yield was greater than 99%, and the olefin:alkane ratio was 99:

1. The specific route is as follows: 。 7. A method for the reductive hydrogenation of arylacetylene using palladium nanowires, characterized in that: 0.32 mol% (0.068 mg) of the prepared palladium nanowires (PdNWs), along with a silicon wafer and 1 mL of methanol solution, were placed in a glass vial. Ultrasonication was used to free the PdNWs in the reaction solvent. Then, 22.72 mg (3 eq.) of NaBH4 and 30.63 mg (0.2 mmol) of 3-ethynylquinoline were added. The vial was stoppered with a rubber stopper and a deflated balloon inserted to maintain constant pressure. The reaction was stirred at room temperature, and the progress of the reaction was monitored by TLC. After 0.5 h of reaction, the reaction was quenched with water. The organic phase was then washed with 3 × 5 mL of brine and dried over anhydrous MgSO4. After vacuum concentration, the resulting mixture was purified by column chromatography using ethyl acetate and n-hexane in a 1:5 volume ratio as the mobile phase. The HPLC yield was greater than 99%, and the olefin:alkane ratio was 95:5, indicating good selectivity. The specific route is as follows: 。

Images