Electrochemical synthesis method of bidentate / polydentate phosphine ligand and hydrogen

Abstract

The invention discloses a bidentate / polydentate phosphine ligand and hydrogen electrochemical synthesis method, and belongs to the technical field of electrochemical synthesis. The method comprises the following steps: dispersing a phosphine source, a nucleophilic reagent and a catalyst in a solvent in an inert gas atmosphere, and carrying out an electrolytic reaction to obtain a bidentate / polydentate phosphine ligand and hydrogen; through an alternating current electrolysis mode, the influence of oxidizing substances on the trivalent P-H reagent in the electrochemical synthesis process is reduced, the P-H reagent is adopted as a raw material, the only co-product is hydrogen, and the method has the advantages of being environmentally friendly, simple and convenient in step, capable of achieving multiple purposes and the like.

Description

Technical Field

[0001] This invention relates to the field of electrochemical synthesis technology, and in particular to an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen. Background Technology

[0002] Hydrogen has the advantage of high calorific value, and its combustion product is water with no harmful gases produced, making it a promising candidate for clean energy. Hydrogen can be obtained through electrolysis of byproducts, but other gases, such as oxygen and chlorine, are easily mixed during the electrolysis reaction, affecting its purity and requiring additional post-processing steps for separation, which is detrimental to process and cost optimization.

[0003] Trivalent phosphine ligands are a core component of organophosphine chemistry. Their phosphorus atoms possess lone pairs of electrons and tunable steric and electronic effects, making them one of the most important ligand classes in transition metal catalysis. These ligands play an irreplaceable role in organic optoelectronic materials, pharmaceutical intermediates, and catalysis science. Currently, traditional techniques typically use P-Cl reagents reacting with corresponding nucleophiles, generating equivalent amounts of halogen waste, which suffers from drawbacks such as complex processes and environmental pollution.

[0004] Electrosynthetic chemistry utilizes electrical energy to drive chemical reactions, replacing traditional chemical oxidants or reducing agents through electron transfer at the electrode surface. It is a green and efficient synthetic technique. Currently, even under nitrogen protection, electrosynthetic reactions using trivalent pH reagents and nucleophiles yield pentavalent phosphorus. This is because trivalent pH reagents have low oxidation potentials and are easily anolyzed to pentavalent P, and oxygen or water in the solvent or system is difficult to completely remove. Therefore, there is currently no method for electrochemically synthesizing trivalent bidentate / multidententate phosphine ligands.

[0005] In summary, this paper presents an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, which uses a simple, green and environmentally friendly process to achieve the synthesis of bidentate / multidentate phosphine ligands and obtain the unique coproduct hydrogen. This method has significant value for fields such as optoelectronics, medicine, catalysis, and energy. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, in a first aspect of the present invention, an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen is provided, which reduces the generation of oxidizing substances and the influence on trivalent pH reagents during the electrochemical synthesis process by using an alternating current electrolysis mode.

[0007] The present invention adopts the following technical solution to achieve the above objectives: An electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen includes the following steps: In an inert gas atmosphere, a phosphine source, a nucleophile, and a catalyst are dispersed in a solvent, and bidentate / multidentate phosphine ligands and hydrogen are obtained by alternating current electrolysis. The phosphine source has the following molecular structure: Formula I: In Equation I, R1 and R2 are independent and defined as C1~C2. 10 Alkyl, C4~C 24 At least one of the aryl groups; The nucleophile is at least one of binary or ternary nucleophiles; the nucleophile is at least one of alkyl and aryl nucleophiles; the nucleophile has 2 to 24 carbon atoms; and the nucleophilic group of the nucleophile is one or more of hydroxyl, mercapto, and amino groups.

[0008] In the above electrochemical synthesis method, the type of phosphine ligand obtained varies with the choice of raw materials. In bidentate / multidentate phosphine ligands, " / " means "and / or".

[0009] Preferably, the catalyst is Sodium bromide, potassium bromide, lithium bromide, sodium iodide, potassium iodide, lithium iodide, sodium chloride, potassium chloride, and lithium chloride are selected as one or more of these compounds; In this context, R3~R6 are independently represented as C1~C6. 10 Alkyl, C6~C 24 At least one of the aryl groups, X - For Cl - ,Br - I - One or more of them.

[0010] Preferably, the molar ratio of the catalyst to the phosphine source is (0.1~0.5):1.

[0011] Preferably, the current density of the alternating current electrolysis reaction is 1~40 mA / cm². 2 The reaction temperature is 0~80 ℃.

[0012] Preferably, the AC frequency of the AC electrolysis reaction is 0.01~10 Hz, and the duty cycle is 20%~80%.

[0013] Specific alternating current frequencies and duty cycles help increase the proportion of trivalent phosphine ligands in the product and optimize product quality.

[0014] Preferably, the solvent is one or more of dichloromethane, dichloroethane, chloroform, acetonitrile, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0015] Preferably, the anode used in the alternating current electrolysis reaction includes any one of carbon sheet, carbon felt, carbon cloth, carbon paper, and platinum sheet; the cathode used is any one of carbon sheet, carbon felt, carbon cloth, carbon paper, platinum sheet, stainless steel, iron sheet, nickel sheet, and nickel-plated platinum electrode.

[0016] In a second aspect of the invention, the application of the bidentate / polydentate phosphine ligand prepared by the above-described electrochemical synthesis method of bidentate / polydentate phosphine ligand and hydrogen is provided, including: using the bidentate / polydentate phosphine ligand to prepare a catalyst.

[0017] Preferably, the catalyst preparation method includes the following steps: under an inert gas atmosphere, a bidentate / multidentate phosphine ligand is coordinated with a transition metal, and then separated and purified to obtain the catalyst.

[0018] More preferably, the transition metal is at least one of palladium, platinum, rhodium and ruthenium.

[0019] Based on the above solutions, the design concept and principle of this invention are as follows: This application employs an alternating current electrolysis mode to obtain trivalent phosphine ligands. The specific mechanism is as follows: using alternating current allows for a rapid switch to cathodic reduction after anodic oxidation, accelerating deprotonation or single-electron transfer and converting easily oxidized phosphorus radical cations into phosphorus radicals. Simultaneously, it suppresses the two-electron oxidation pathway, preventing phosphorus radical cations from further capturing oxygen to form stable P=O bonds, thus reducing the accumulation of pentavalent phosphorus due to continuous oxidation. Therefore, trivalent bidentate / multidentate phosphine ligands are synthesized electrochemically, with hydrogen gas as the sole coproduct.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen. Using a pH reagent as a raw material, the method achieves the synthesis of bidentate / multidentate phosphine ligands based on a specific process route, and the only coproduct is hydrogen. This method has the advantages of being green and environmentally friendly, simple in steps, and achieving multiple benefits.

[0021] This invention provides applications for bidentate / multidentate phosphine ligands prepared by the above synthesis method, which have broad application prospects in fields such as catalysis science, optoelectronic materials, and biomedicine. Attached Figure Description

[0022] Figure 1 The 1H NMR spectrum and 1P NMR spectrum of the sulfide products obtained in Example 1 are shown. Figure 2 The 1H NMR spectrum and 1P NMR spectrum of the oxidation product obtained in Example 1 are shown. Figure 3 This describes the mechanisms of alternating current (AC) and direct current (DC) electrolysis reactions. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0025] The following are the test methods involving performance parameters in the implementation: Structural characterization: Since most of the obtained trivalent phosphine ligands are unstable in air, sulfur was added to convert the product into the corresponding pentavalent phosphine compound, which was then separated by column chromatography and characterized by nuclear magnetic resonance.

[0026] Characterization of phosphorus valence in the product: The trivalent phosphine ligand in the product can continue to react with sulfur, while the oxidized pentavalent phosphine compound cannot react with sulfur. After the obtained product is reacted with excess sulfur, the sulfidation product and the oxidation product are separated by column chromatography. The molar ratio of the sulfidation product to the oxidation product is calculated, and the proportion of trivalent phosphorus and pentavalent phosphorus is calculated.

[0027] Example 1 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, the steps of which are as follows:

[0028] Under an argon atmosphere, 0.7 mmol of diphenylphosphine, 0.25 mmol of resorcinol, and 0.14 mmol of tetrabutylammonium bromide were dispersed in 10 mL of N,N-dimethylformamide. The mixture was then subjected to an argon atmosphere at 35 °C using carbon and platinum electrodes at a current density of 20 mA / cm². 2 The electrolysis mode was alternating current with a frequency of 3.0 Hz and a duty cycle of 40%. After 2 hours of reaction, the product was obtained with a Faraday efficiency of 91%.

[0029] The product was converted to the corresponding pentavalent phosphine compound by the addition of sulfur. After column chromatography separation, the structure was characterized by NMR. The NMR spectra of the sulfide product (H1N and N2N) and the oxidation product (H1N and N2N) are shown below. Figure 1 , Figure 2 As shown.

[0030] Example 2 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, which is basically the same as that in Example 1, except that the current density of the electrolysis reaction in this embodiment is 1 mA / cm². 2 With the same total power, the product Faraday efficiency is 92%.

[0031] Example 3 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, which is basically the same as that in Example 1, except that the current density of the electrolysis reaction in this embodiment is 40 mA / cm². 2 With the same total power, the product Faraday efficiency is 86%.

[0032] Example 4 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, which is basically the same as that in Example 1, except that the electrolysis reaction temperature is 0 °C and the product Faraday efficiency is 77%.

[0033] Example 5 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, which is basically the same as that in Example 1, except that the electrolysis reaction temperature in this embodiment is 80 °C and the product Faraday efficiency is 82%.

[0034] Example 6 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, which is basically the same as that in Example 1, except that 0.14 mmol of tetrabutylammonium bromide is replaced with tetrabutylammonium chloride in this embodiment, and the product Faraday efficiency is 86%.

[0035] Example 7 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0036] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 3,5-dihydroxytoluene, and the product Faradaic efficiency is 77%.

[0037] 1 H NMR (400 MHz, Chloroform-d) δ 7.94 - 7.83 (m, 9H), 7.53 - 7.43 (m,4H), 7.46 - 7.37 (m, 8H), 6.69 - 6.62 (m, 3H), 2.12 (s, 3H).

[0038] Example 8 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0039] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 3,5-dihydroxybenzonitrile, the AC frequency is replaced with 0.5 Hz, the duty cycle is replaced with 22%, and the product Faraday efficiency is 33%.

[0040] 1 H NMR (400 MHz, Chloroform-d) δ 7.93 - 7.83 (m, 8H), 7.59 - 7.51 (m,4H), 7.51 - 7.43 (m, 8H), 7.17 (p, J = 1.9 Hz, 1H), 7.09 (q, J = 1.6 Hz, 2H). Example 9 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0041] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of catechol, and the product Faradaic efficiency is 90%.

[0042] 1 H NMR (400 MHz, Chloroform-d) δ 7.99 - 7.89 (m, 8H), 7.50 - 7.41 (m,4H), 7.37 - 7.28 (m, 8H), 7.11 - 7.04 (m, 2H), 6.91 - 6.82 (m, 2H). Example 10 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0043] Compared with the preparation method in Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 4-methylcatechol, and the product Faradaic efficiency is 80%.

[0044] 1H NMR (400 MHz, Chloroform-d) δ 7.97 - 7.88 (m, 8H), 7.46 - 7.40 (m,4H), 7.35 - 7.26 (m, 8H), 6.94 - 6.87 (m, 2H), 6.69 - 6.62 (m, 1H), 2.07 (s,3H). Example 11 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0045] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of p-tert-butylcatechol, and the product Faradaic efficiency is 99%.

[0046] 1 H NMR (400 MHz, Chloroform-d) δ 8.03 - 7.90 (m, 8H), 7.52 - 7.40 (m,4H), 7.37 - 7.28 (m, 9H), 7.06 - 7.01 (m, 1H), 6.97 - 6.90 (m, 1H), 6.88 -6.81 (m, 1H), 1.06 - 1.01 (m, 9H). Example 12 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0047] Compared with the preparation method in Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 4-chlorocatechol, and the product Faradaic efficiency is 74%.

[0048] 1 H NMR (400 MHz, Chloroform-d) δ 7.97 - 7.86 (m, 8H), 7.50 - 7.41 (m,4H), 7.37 - 7.28 (m, 8H), 7.12 - 7.07 (m, 1H), 7.02 - 6.97 (m, 1H), 6.87 -6.81 (m, 1H). Example 13 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0049] Compared with the preparation method in Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 3,4-dihydroxybenzonitrile, and the product Faradaic efficiency is 82%.

[0050] 1 H NMR (400 MHz, Chloroform-d) δ 7.97 - 7.85 (m, 8H), 7.56 - 7.44 (m,4H), 7.41 - 7.29 (m, 9H), 7.26 - 7.17 (m, 2H). Example 14 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0051] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of hydroquinone, and the product Faraday efficiency is 66%.

[0052] 1 H NMR (400 MHz, Chloroform-d) δ 7.97 - 7.87 (m, 8H), 7.58 - 7.49 (m,4H), 7.49 - 7.40 (m, 8H), 6.91 - 6.87 (m, 4H). Example 15 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0053] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 2,5-dihydroxytoluene, and the product Faraday efficiency is 78%.

[0054] 1 H NMR (400 MHz, Chloroform-d) δ 7.99 - 7.87 (m, 8H), 7.54 - 7.38 (m,12H), 6.89 (d, J= 2.9 Hz, 1H), 6.78 - 6.71 (m, 1H), 6.66 - 6.58 (m, 1H). Example 16 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0055] Compared with the preparation method in Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 2,5-dihydroxybiphenyl, and the product faradaic efficiency is 90%.

[0056] 1 H NMR (400 MHz, Chloroform-d) δ 7.98 - 7.86 (m, 4H), 7.67 - 7.56 (m,4H), 7.53 - 7.46 (m, 2H), 7.46 - 7.36 (m, 6H), 7.33 - 7.21 (m, 9H), 7.20 -7.15 (m, 1H), 7.05 - 7.00 (m, 1H), 6.87 - 6.79 (m, 1H). Example 17 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0057] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of resorcinol, the AC frequency is replaced with 8.9 Hz, the duty cycle is replaced with 73%, and the product Faraday efficiency is 72%.

[0058] 1 H NMR (400 MHz, Chloroform-d) δ 8.02 - 7.84 (m, 9H), 7.60 (d, J = 8.1Hz, 1H), 7.52 - 7.36 (m, 13H), 7.36 - 7.28 (m, 2H), 7.10 (d, J = 2.2 Hz, 1H). Example 18 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0059] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 2,3-dihydroxynaphthalene, and the product Faradaic efficiency is 77%.

[0060] 1 H NMR (400 MHz, Chloroform-d) δ 8.06 - 7.93 (m, 8H), 7.52 - 7.44 (m,8H), 7.38 - 7.31 (m, 8H), 7.31 - 7.27 (m, 2H). Example 19 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0061] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 1,4-dihydroxynaphthalene, and the product Faradaic efficiency is 86%.

[0062] 1 H NMR (400 MHz, Chloroform-d) δ 8.08 - 7.96 (m, 10H), 7.53 - 7.38 (m, 14H), 6.88 (s, 2H). Example 20 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0063] Compared with the preparation method in Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 2,2'-dihydroxybiphenyl, and the product faradaic efficiency is 76%.

[0064] 1 H NMR (400 MHz, Chloroform-d) δ 7.70 - 7.50 (m, 6H), 7.38 - 7.30 (m,6H), 7.26 - 7.13 (m, 12H), 7.03 (t, J = 7.4 Hz, 2H). Example 21 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0065] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 1,1'-bi-2-naphthol, and the product Faraday efficiency is 52%.

[0066] 1 H NMR (400 MHz, Chloroform-d) δ 7.83 - 7.76 (m, 4H), 7.72 - 7.66 (m,2H), 7.58 - 7.48 (m, 4H), 7.37 - 7.25 (m, 8H), 7.25 - 7.17 (m, 6H), 7.16 -7.08 (m, 4H), 7.07 - 7.00 (m, 4H). Example 22 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0067] Compared with the preparation method in Example 1, the difference in this example is that 0.7 mmol of diphenylphosphine, 0.25 mmol of resorcinol and 0.14 mmol of tetrabutylammonium bromide are replaced with 1.0 mmol of diphenylphosphine, 0.25 mmol of phloroglucinol and 0.2 mmol of tetrabutylammonium bromide, and the product Faradaic efficiency is 70%.

[0068] 1 H NMR (400 MHz, Chloroform-d) δ 7.87 - 7.77 (m, 12H), 7.53 - 7.46(m, 6H), 7.46 - 7.37 (m, 12H), 6.71 (q, J = 1.3 Hz, 3H). Example 23 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0069] Compared with the preparation method in Example 1, the difference in this example is that 0.7 mmol of diphenylphosphine, 0.25 mmol of resorcinol and 0.14 mmol of tetrabutylammonium bromide are replaced with 1.0 mmol of diphenylphosphine, 0.25 mmol of 1,2,4-phenylpyrogallol and 0.2 mmol of tetrabutylammonium bromide, and the product Faradaic efficiency is 72%.

[0070] 1 H NMR (400 MHz, Chloroform-d) δ 7.91 - 7.76 (m, 12H), 7.52 - 7.37(m, 10H), 7.35 - 7.26 (m, 8H), 7.00 (d, J = 2.7 Hz, 1H), 6.93 (d, J = 9.1 Hz, 1H), 6.63 (d, J = 9.2, 2.0 Hz, 1H). Example 24 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0071] Compared with the preparation method in Example 1, the difference in this example is that 0.7 mmol of diphenylphosphine is replaced with 0.7 mmol of di-tert-butylphosphine, and the product Faraday efficiency is 81%.

[0072] 1 H NMR (400 MHz, Chloroform-d) δ 7.34 (tt, J = 2.3, 1.1 Hz, 1H), 7.20(t, J = 8.2 Hz, 1H), 7.06 - 6.99 (m, 2H), 1.43 (d, 36H). Example 25 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0073] Compared with the preparation method of Example 14, the difference in this example is that 0.7 mmol of diphenylphosphine is replaced with 0.7 mmol of di-tert-butylphosphine, and the product Faraday efficiency is 88%.

[0074] 1H NMR (400 MHz, Chloroform-d) δ 7.21 (s, 4H), 1.43 (d, J = 16.3 Hz, 36H). Example 26 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0075] Compared with the preparation method of Example 9, the difference in this example is that 0.7 mmol of diphenylphosphine is replaced with 0.7 mmol of di-tert-butylphosphine, and the product Faraday efficiency is 81%.

[0076] 1 H NMR (400 MHz, Chloroform-d) δ 8.18 - 8.09 (m, 2H), 7.02 - 6.93 (m,2H), 1.44 (d, J = 16.5 Hz, 36H). Example 27 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0077] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 1,2-ethylenedithiol, the AC frequency is replaced with 4.9 Hz, the duty cycle is replaced with 27%, and the product Faraday efficiency is 88%.

[0078] 1 H NMR (400 MHz, Chloroform-d) δ 7.94 - 7.78 (m, 8H), 7.58 - 7.37 (m,12H), 3.19 - 3.03 (m, 4H). Example 28 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0079] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 1,3-propanedithiol, and the product Faradaic efficiency is 79%.

[0080] 1H NMR (400 MHz, Chloroform-d) δ 7.97 - 7.85 (m, 8H), 7.51 - 7.30 (m,12H), 3.04 - 2.84 (m, 4H), 1.83 (p, J = 7.0 Hz, 2H). Example 29 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0081] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 1,6-hexanedithiol, and the product faradaic efficiency is 92%.

[0082] 1 H NMR (400 MHz, Chloroform-d) δ 6.79 - 6.68 (m, 8H), 6.32 - 6.17 (m,12H), 1.73 - 1.58 (m, 4H), 0.33 - 0.22 (m, 4H), 0.11 - -0.03 (m, 4H). Example 30 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0083] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 4',4-dimercaptodiphenyl sulfide, the AC frequency is replaced with 4.4 Hz, the duty cycle is replaced with 25%, and the product Faraday efficiency is 40%.

[0084] 1 H NMR (400 MHz, Chloroform-d) δ 8.02 - 7.89 (m, 8H), 7.54 - 7.40 (m,12H), 7.30 - 7.20 (m, 4H), 7.14 - 7.04 (m, 4H). Example 31 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0085] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 4-hydroxythiophenol, and the product Faradaic efficiency is 75%.

[0086] 1 H NMR (400 MHz, Chloroform-d) δ 7.99 - 7.83 (m, 8H), 7.56 - 7.38 (m,12H), 7.21 - 7.15 (m, 2H), 6.95 - 6.87 (m, 2H). Example 32 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0087] Compared with the preparation method in Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 4-aminophenol, and the product Faraday efficiency is 64%.

[0088] 1 H NMR (400 MHz, Chloroform-d) δ 8.01 - 7.85 (m, 8H), 7.54 - 7.39 (m,12H), 6.85 - 6.73 (m, 4H), 4.84 (d, J = 6.2 Hz, 1H). Example 33 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0089] Compared with the preparation method of Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 2-methyl-4-aminophenol, and the product Faraday efficiency is 65%.

[0090] 1 H NMR (400 MHz, Chloroform-d) δ 8.02 - 7.87 (m, 8H), 7.55 - 7.40 (m,12H), 6.73 (d, J = 2.8 Hz, 1H), 6.64 (dd, J = 8.7, 1.5 Hz, 1H), 6.52 (dd, J= 8.8, 2.9 Hz, 1H), 4.79 (d, J = 6.2 Hz, 1H), 2.11 (s, 3H). Example 34 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0091] Compared with the preparation method in Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 4-aminothiophenol, and the product Faraday efficiency is 77%.

[0092] 1 H NMR (400 MHz, DMSO-d6) δ 8.34 (d, J = 8.6 Hz, 1H), 8.00 - 7.84 (m,8H), 7.64 - 7.48 (m, 12H), 7.30 (d, J = 2.0 Hz, 1H), 7.09 (d, J = 8.4 Hz, 1H), 6.99 (t, J = 8.0 Hz, 1H), 6.77 (d, J = 7.6 Hz, 1H). Example 35 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0093] Compared with the preparation method in Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 3-aminothiophenol, and the product Faraday efficiency is 63%.

[0094] 1 H NMR (400 MHz, DMSO-d6) δ 8.42 (d, J = 8.9 Hz, 1H), 7.97 - 7.83 (m,8H), 7.64 - 7.47 (m, 12H), 7.12 - 7.05 (m, 2H), 6.98 - 6.91 (m, 2H). Example 36 This embodiment provides an electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, with the target product as follows:

[0095] Compared with the preparation method in Example 1, the difference in this example is that 0.25 mmol of resorcinol is replaced with 0.25 mmol of 3-hydroxythiophenol, and the product Faraday efficiency is 74%.

[0096] 1 H NMR (400 MHz, Chloroform-d) δ 7.96 - 7.84 (m, 8H), 7.53 - 7.36 (m,12H), 7.16 (p, J = 1.9 Hz, 1H), 7.11 - 6.97 (m, 3H). Example 37 This embodiment provides the application of the bidentate / multidentate phosphine ligand prepared by the electrochemical synthesis method of bidentate / multidentate phosphine ligand and hydrogen in the preparation of catalysts. The steps include: under an argon atmosphere, dispersing the product obtained in Example 1 and bis(acetonitrile)palladium(II) chloride in dichloromethane, heating to 40 °C, stirring for 2 h, cooling and adding petroleum ether, filtering, washing the obtained solid three times with petroleum ether, and vacuum drying to obtain the bidentate palladium chloride catalyst.

[0097] Comparative Example 1 The difference between this comparative example and the preparation method in Example 1 is that the argon atmosphere is replaced with an air atmosphere.

[0098] Comparative Example 2 The difference between this comparative example and the preparation method of Example 1 is that the electrolysis mode is replaced with direct current.

[0099] Comparative Example 3 The difference between this comparative example and the preparation method of Example 8 is that the electrolysis mode is replaced with direct current.

[0100] Comparative Example 4 The difference between this comparative example and the preparation method of Example 17 is that the electrolysis mode is replaced with direct current.

[0101] Comparative Example 5 The difference between this comparative example and the preparation method of Example 27 is that the electrolysis mode is replaced with direct current.

[0102] Comparative Example 6 The difference between this comparative example and the preparation method of Example 30 is that the electrolysis mode is replaced with direct current.

[0103] Based on the above method, the proportions of trivalent and pentavalent phosphorus were calculated. The proportions of product valence states in the examples and comparative examples are shown in Table 1.

[0104] Table 1: Proportion of Product Valence States in Examples and Comparative Examples

[0105] The mechanisms of alternating current electrolysis and direct current electrolysis are as follows: Figure 3 As shown, data from Examples 1 and 2, 8 and 4, 17 and 4, 27 and 5, and 30 and 6 indicate that the substrate yields a higher proportion of trivalent phosphine compounds when electrolyzed in alternating current mode, and a higher proportion of pentavalent phosphine compounds when electrolyzed in direct current mode.

[0106] In summary, this application disperses a phosphine source, nucleophile, and catalyst in a solvent under an inert gas atmosphere, and obtains bidentate / multidentate phosphine ligands and hydrogen through an electrolytic reaction. By using an alternating current electrolysis mode, the influence of oxidizing substances on the trivalent pH reagent during the electrochemical synthesis process is reduced. Furthermore, this invention uses a pH reagent as a raw material, and the only coproduct is hydrogen, which has the advantages of being green and environmentally friendly, simple in procedure, and achieving multiple benefits.

[0107] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. An electrochemical synthesis method for bidentate / multidentate phosphine ligands and hydrogen, characterized in that, Includes the following steps: In an inert gas atmosphere, a phosphine source, a nucleophile, and a catalyst are dispersed in a solvent, and bidentate / multidentate phosphine ligands and hydrogen are obtained by alternating current electrolysis. The phosphine source has the following molecular structure: Formula I: In Equation I, R1 and R2 are independent and defined as C1~C2. 10 Alkyl, C4~C 24 At least one of the aryl groups; The nucleophile is at least one of binary or ternary nucleophiles; the nucleophile is at least one of alkyl and aryl nucleophiles; the nucleophile has 2 to 24 carbon atoms; and the nucleophilic group of the nucleophile is one or more of hydroxyl, mercapto, and amino groups.

2. The electrochemical synthesis method of bidentate / multidentate phosphine ligands and hydrogen according to claim 1, characterized in that: The catalyst is Sodium bromide, potassium bromide, lithium bromide, sodium iodide, potassium iodide, lithium iodide, sodium chloride, potassium chloride, and lithium chloride are selected as one or more of these compounds; In this context, R3~R6 are independently represented as C1~C6. 10 Alkyl, C6~C 24 At least one of the aryl groups, X - For Cl - ,Br - I - One or more of them.

3. The electrochemical synthesis method of bidentate / multidentate phosphine ligands and hydrogen according to claim 1, characterized in that: The molar ratio of the catalyst to the phosphine source is (0.1~0.5):

1.

4. The electrochemical synthesis method of bidentate / multidentate phosphine ligands and hydrogen according to claim 1, characterized in that: The current density of the alternating current electrolysis reaction is 1~40 mA / cm². 2 The reaction temperature is 0~80 ℃.

5. The electrochemical synthesis method of bidentate / multidentate phosphine ligands and hydrogen according to claim 1, characterized in that: The alternating current frequency of the electrolytic reaction is 0.01~10 Hz, and the duty cycle is 20%~80%.

6. The electrochemical synthesis method of bidentate / multidentate phosphine ligands and hydrogen according to claim 1, characterized in that: The solvent is one or more of dichloromethane, dichloroethane, chloroform, acetonitrile, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

7. The electrochemical synthesis method of bidentate / multidentate phosphine ligands and hydrogen according to claim 1, characterized in that: The anode used in the alternating current electrolysis reaction includes any one of carbon sheet, carbon felt, carbon cloth, carbon paper, and platinum sheet; the cathode used is any one of carbon sheet, carbon felt, carbon cloth, carbon paper, platinum sheet, stainless steel, iron sheet, nickel sheet, and nickel-plated platinum electrode.

8. The application of a bidentate / multidentate phosphine ligand prepared by the electrochemical synthesis method of bidentate / multidentate phosphine ligands and hydrogen as described in any one of claims 1 to 7, characterized in that, include: Bidentate / multidentate phosphine ligands were used to prepare catalysts.

9. The application according to claim 8, characterized in that, The catalyst preparation method includes the following steps: under an inert gas atmosphere, a bidentate / multidentate phosphine ligand is coordinated with a transition metal, and then separated and purified to obtain the catalyst.

10. The application according to claim 9, characterized in that: The transition metal is at least one of palladium, platinum, rhodium, and ruthenium.

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