Electrocatalytic synthesis method of aryl sulfone compound

Abstract

The invention relates to preparation of an aryl sulfone compound, in particular to an electrocatalytic synthesis method of the aryl sulfone compound, which comprises the following steps: taking phenylhydrazine hydrochloride and sodium aryl sulfinate as raw materials, and synthesizing the aryl sulfone compound through oxidation free radical coupling by utilizing an electrocatalytic technology. The method comprises the following steps: S1, sequentially adding phenylhydrazine hydrochloride, sodium aryl sulfinate, a catalyst and a ligand into a sealed electrolytic tank, and then adding electrolyte and a solvent; s2, taking a graphite felt electrode as an anode, a platinum sheet electrode as a cathode and oxygen as an oxidation source, sealing, electrifying and stirring at room temperature, and carrying out a synthetic reaction; and S3, taking out a final product after the reaction is finished, and carrying out column chromatography separation to obtain the aryl sulfone compound. According to the method, the reaction can be realized under the mild conditions of normal temperature and normal pressure by utilizing an electro-catalysis technology, extremely high atom economy is provided, the adaptability to various functional groups and the yield of the aryl sulfone compound are enhanced, and the method is economical, efficient and environment-friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of compound preparation, and particularly relates to an electrocatalytic synthesis method of aryl sulfone compounds. Background Art

[0002] Aryl sulfone compounds have important application values in the fields of organic synthesis, medicinal chemistry and materials science. In the pharmaceutical industry, they are key intermediates for a variety of drugs. For example, in the synthesis of the anti-leprosy drug dapsone, the aryl sulfone structure is indispensable. In addition, aryl sulfones are also widely used in agrochemicals and can be used in the synthesis of agrochemicals such as herbicides and insecticides. In the field of polymer materials, such compounds can be used as structural units to prepare high-performance polymers such as polyamideimide, endowing the materials with more excellent transparency, heat resistance and antioxidant properties. Therefore, developing efficient and green synthesis methods for aryl sulfone compounds is of great significance for improving the performance of pharmaceuticals, agrochemicals and polymer materials.

[0003] On the other hand, phenylhydrazine is an important industrial by-product in recent years and is generated in large quantities during the production of a variety of commercially valuable chemicals. For example, in the synthesis of drugs (such as the antipyretic and analgesic drug antipyrine and the analgesic phenacetin), side reactions involving hydrazine derivatives usually result in the large production of phenylhydrazine. Similarly, in the dye manufacturing process, especially in the production of azo dyes (such as C.I. Acid Red 88 and C.I. Direct Blue 6), the aromatic amine coupling reaction also produces phenylhydrazine as a by-product.

[0004] In addition, in the field of agrochemicals, during the synthesis of intermediates in the production of herbicides (such as pyrazolate) and insecticides (such as carbofuran), phenylhydrazine is also generated. Due to the high toxicity of phenylhydrazine, if not properly disposed of, it will cause serious harm to the environment and public health. Therefore, efficiently converting phenylhydrazine by-products into high-value-added chemicals can not only reduce industrial waste emissions and improve resource utilization rates, but also conform to the sustainable development principle of green chemistry.

[0005] However, the current methods for the efficient utilization of phenylhydrazine are still relatively limited, and innovative conversion strategies are urgently needed.

[0006] There are mainly two existing methods for synthesizing aryl sulfones: (1) Electrophilic aromatic substitution reaction, that is, the reaction of aromatic hydrocarbons with sulfonylation reagents. However, this method usually has problems such as poor regioselectivity and easy generation of over-sulfonated by-products; (2) Sulfur (S)-arylation strategy, that is, the reaction of sulfonates with aryl halides. However, this method usually requires noble metal catalysts, and for haloarenes substituted with electron-donating groups, the reaction activity is relatively low. This is because the p-π conjugation effect between the halogen and the aromatic ring in aryl halides increases the bond energy of the C-X bond, resulting in a relatively high reaction activation energy. In addition, this method often requires high temperature, equimolar catalysts, and harsh reaction conditions, thus limiting its feasibility in practical applications.

[0007] Therefore, there is an urgent need to develop a mild, efficient, and noble-metal-catalyst-free synthesis strategy to expand the synthesis route of aryl sulfones and enhance the feasibility of their industrial applications.

[0008] In recent years, electrocatalytic synthesis has received extensive attention as a green and sustainable organic synthesis strategy. In 2023, IUPAC listed synthetic electrochemistry as one of the top ten emerging technologies in the field of chemistry. Compared with traditional thermal catalytic methods, electrocatalytic reactions can usually be carried out at room temperature and atmospheric pressure, avoiding problems such as catalyst sintering and carbon deposition caused by high temperature and high pressure, and being able to precisely control the reaction process. In addition, electrocatalytic methods directly initiate redox reactions through electron transfer, without the need to add additional chemical oxidants or reductants, thus significantly reducing the generation of chemical waste and conforming to the core concept of green chemistry.

[0009] Therefore, electrocatalytic technology shows great application potential in the field of organic synthesis, especially in the construction of C-S bonds and oxidative radical coupling. Summary of the Invention

[0010] Aiming at the deficiencies of the existing technology, the present invention proposes a method for synthesizing aryl sulfone compounds based on electrocatalytic technology, which uses a mild oxidative radical coupling strategy to achieve the efficient synthesis of aryl sulfones under low energy consumption conditions.

[0011] The technical solution adopted by the present invention:

[0012] An electrocatalytic synthesis method of aryl sulfones, using arylhydrazine compounds and sodium arylsulfinates as raw materials, and synthesizing aryl sulfone compounds through oxidative radical coupling under electrocatalytic technology. The process includes:

[0013] Step S1, take phenylhydrazine hydrochloride, sodium arylsulfinate, a catalyst and a ligand, and sequentially add them into a sealed electrolytic cell, and then add an electrolyte and a solvent;

[0014] Step S2: Using a graphite felt electrode as the anode, a platinum sheet electrode as the cathode, and oxygen as the oxidation source, seal and energize for stirring at room temperature to carry out the synthesis reaction; the reaction equation is:

[0015]

[0016] Among them, R 1 , R 2 is hydrogen, an electron-donating group or an electron-withdrawing group;

[0017] Step S3: After the reaction is completed, take out the final product and obtain the aryl sulfone compound by column chromatography separation.

[0018] Among them, the chemical formula of phenylhydrazine hydrochloride is The arylsulfinate sodium is The chemical formula is the aryl sulfone compound;

[0019] R is hydrogen, an electron-donating group or an electron-withdrawing group. The electron-donating groups are methyl, methoxy, ethyl, ethoxy, isopropyl, tert-butyl, methylthio, phenyl, alkoxy or amino, etc. The electron-withdrawing groups are nitro, cyano, trifluoromethyl, sulfonic acid group, aldehyde group, chlorine, fluorine, acyl group, etc.

[0020] The solvent is dimethyl sulfoxide, acetonitrile, tetrahydrofuran or N,N-dimethylformamide.

[0021] The electrolyte is tetrabutylammonium bromide, tetrabutylammonium tetrafluoroborate, tetrabutylammonium perchlorate or tetrabutylammonium iodide.

[0022] The catalyst is anhydrous nickel bromide, anhydrous nickel chloride, anhydrous nickel iodide, dibromo-bis(pyridine)nickel or nickel(II) ethylene glycol dimethyl ether complex.

[0023] The ligand is 4-cyanopyridine, (S)-3,3'-diphenyl-1,1'-binaphthyl-2,2'-diol, (1S,2S)-cyclohexane-1,2-diamine, 4,4',6,6'-tetramethyl-2,2'-bipyridine, phenanthroline or 2,2'-bipyrazine.

[0024] The molar ratio of the phenylhydrazine hydrochloride to the arylsulfinate sodium is 1:1 - 3, preferably 1:2. The addition amount of the solvent is 6 mL of solvent per 0.3 mmol of phenylhydrazine hydrochloride.

[0025] Among them, the addition amount of the nickel transition metal salt is 1 - 10 mol% of the phenylhydrazine hydrochloride, preferably 10 mol%. The addition amount of the ligand is 1 - 20 mol% of the phenylhydrazine hydrochloride, preferably 20 mol%.

[0026] Advantageous effects of the invention:

[0027] 1. The present invention provides a new method for synthesizing aryl sulfones by electrocatalysis. Using phenylhydrazine, a common by-product in chemical production, as a raw material, the harmful by-product is converted into a high-value-added product, which not only improves the resource utilization rate but also is beneficial to environmental protection, embodying the core concept of green chemistry. It can not only directly utilize the arylhydrazine by-product as a raw material to reduce the emission of harmful waste, but also does not rely on noble metal catalysts, and has high selectivity, high atom economy, and good substrate generality.

[0028] 2. The method for synthesizing aryl sulfones under electrocatalytic conditions of the present invention solves the problems of realizing oxidative radical coupling under mild conditions and high selectivity of functional groups. This method is economical and efficient, has mild reaction conditions, high yields, and high selectivity, and does not require reactions to occur under high temperature or light source irradiation. The present invention provides a new solution for the sustainable synthesis of aryl sulfones, expands the application of electrocatalysis in organic synthesis, and provides a more environmentally friendly and efficient synthesis strategy for multiple fields such as medicine, agrochemicals, and materials science.

[0029] 3. Different from the traditional heating or blue light reaction conditions, the present invention uses electrocatalytic technology to achieve the reaction under mild conditions of normal temperature and pressure, providing extremely high atom economy, enhancing the adaptability to various functional groups, and the yield of aryl sulfones. This method is not only efficient but also highly selective.

[0030] 4. The present invention uses nickel bromide with a relatively low cost as a catalyst, but can achieve a catalytic effect comparable to that of noble metal catalysts, significantly reducing the production cost. At the same time, unnecessary side reactions are reduced, further reducing the production cost. This opens up a new path for industrial application and shows broad development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is the 1H NMR spectrum of diphenyl sulfone in Example 1;

[0032] Figure 2 It is the 13C NMR spectrum of diphenyl sulfone in Example 1;

[0033] Figure 3 It is the 1H NMR spectrum of 4-methoxydiphenyl sulfone in Example 2;

[0034] Figure 4 It is the 13C NMR spectrum of 4-methoxydiphenyl sulfone in Example 2;

[0035] Figure 5 It is the 1H NMR spectrum of 4-methyldiphenyl sulfone in Example 13;

[0036] Figure 61H NMR spectrum of 4-methyl diphenyl sulfone in Example 13;

[0037] Figure 7 1H NMR spectrum of 4-nitro diphenyl sulfone in Example 19;

[0038] Figure 8 13C NMR spectrum of 4-nitro diphenyl sulfone in Example 19. Detailed implementation mode

[0039] The present invention will be described in more detail below through specific implementation modes, so as to facilitate the understanding of the technical solution of the present invention, but it is not used to limit the protection scope of the present invention.

[0040] Example 1: Preparation of diphenyl sulfone

[0041] First, take 0.3 mmol of phenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, and then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate, and use 6 mL of MeCN as a solvent. Add these components to a 25 mL sealed electrolytic cell in sequence.

[0042] Use a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, use oxygen as the oxygen source, and perform sealed electrolytic stirring at room temperature (current intensity I = 6 mA), and the reaction lasts for 24 hours. After the reaction is completed, take out the sample and detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product diphenyl sulfone with a yield of 86%.

[0043] Figure 1 1H NMR spectrum of diphenyl sulfone in Example 1. The 1H NMR characterization of diphenyl sulfone is as follows: 1 H NMR(400MHz,CDCl 3 )δ7.95(dd,J=5.9,3.9Hz,5H),7.61–7.53(m,1H),7.56(s,1H),7.57–7.45(m,7H).

[0044] Figure 2 13C NMR spectrum of diphenyl sulfone in Example 1. The 13C NMR characterization of diphenyl sulfone is as follows: 13 CNMR(101MHz,CDCl3)δ141.60,133.23,129.31,127.65.

[0045] The reaction equation is as follows:

[0046]

[0047] Example 2: Preparation of 4-Methoxydiphenyl Sulfone

[0048] First, take 0.3 mmol of 4-methoxyphenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, and then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate and use 6 mL of MeCN as a solvent. Add these components sequentially into a 25 mL sealed electrolytic cell.

[0049] Use a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, use oxygen as the oxygen source, and perform sealed electrolytic stirring at room temperature (current intensity I = 6 mA). The reaction lasts for 24 hours. After the reaction is completed, take out the sample and detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product 4-methoxydiphenyl sulfone with a yield of 95%.

[0050] Figure 3 This is the 1H NMR spectrum of 4-methoxydiphenyl sulfone in Example 2. The 1H NMR characterization of 4-methoxydiphenyl sulfone is as follows: 1 H NMR(400MHz,CDCl 3 )δ7.90(ddd,J=14.4,7.5,1.7Hz,4H),7.58–7.44(m,3H),7.02–6.92(m,2H),3.84(s,3H).

[0051] Figure 4 This is the 13C NMR spectrum of 4-methoxydiphenyl sulfone in Example 2. The 13C NMR characterization of 4-methoxydiphenyl sulfone is as follows: 13 C NMR(101MHz,CDCl 3 )δ163.39,142.38,133.12,132.85,129.89,129.21,127.31,114.53,55.66.

[0052] The reaction equation is as follows:

[0053]

[0054] Example 3: Preparation of 2-Methyldiphenyl Sulfone

[0055] First, take 0.3 mmol of 2-methylphenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, and then add 10 mol% of anhydrous NiBr 2As a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then 1 mmol of tetrabutylammonium tetrafluoroborate was added, and 6 mL of MeCN was used as the solvent. These components were sequentially added to a 25 mL sealed electrolytic cell.

[0056] A graphite felt electrode was used as the anode, a platinum sheet electrode was used as the cathode, oxygen was used as the oxygen source, and sealed electrolysis with stirring was carried out at room temperature (current intensity I = 6 mA), and the reaction continued for 24 hours. After the reaction was completed, the sample was taken out to detect the final product by thin layer chromatography (TCL), and further separated and purified by column chromatography to obtain the final product 2-methyldiphenyl sulfone with a yield of 83%.

[0057] The 1H NMR characterization of 2-methyldiphenyl sulfone is as follows: 1 HNMR(400MHz,Chloroform-d)δ2.28(s,3H),7.05(m,1H),7.21(m,1H),7.32(m,3H),7.45(m,1H),7.75(m,2H),8.04(dd,J=7.8,1.5Hz,1H).

[0058] The 13C NMR characterization of 2-methyldiphenyl sulfone is as follows: 13 C NMR(101MHz,Chloroform-d)δ20.1,126.6,127.8,129.1,129.3,132.6,133.1,133.6,138.2,138.7,141.5.

[0059] The reaction equation is as follows:

[0060] Example 4: Preparation of 3-methyldiphenyl sulfone

[0061] First, 0.3 mmol of 3-methylphenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate were taken, and then 10 mol% of anhydrous NiBr 2 As a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then 1 mmol of tetrabutylammonium tetrafluoroborate was added, and 6 mL of MeCN was used as the solvent. These components were sequentially added to a 25 mL sealed electrolytic cell.

[0062] A graphite felt electrode was used as the anode, a platinum sheet electrode was used as the cathode, oxygen was used as the oxygen source, and sealed electrolysis with stirring was carried out at room temperature (current intensity I = 6 mA), and the reaction continued for 24 hours. After the reaction was completed, the sample was taken out to detect the final product by thin layer chromatography (TCL), and further separated and purified by column chromatography to obtain the final product 3-methyldiphenyl sulfone with a yield of 89%.

[0063] 1H NMR spectrum of 3-methyldiphenyl sulfone: 1 H NMR(400MHz,Chloroform-d)δ2.42(s,3H),7.38(m,2H),7.51(dd,J=8.3,6.6Hz,2H),7.56(m,1H),7.75(m,2H),7.95(m,2H).

[0064] The 13C NMR characterization of 3-methyldiphenyl sulfone is as follows: 13 C NMR(101MHz,Chloroform-d)δ21.5,124.7,127.7,127.9,129.1,129.3,133.1,134.1,139.6,141.4,141.6.

[0065] The reaction equation is as follows:

[0066]

[0067] Example 5: Preparation of 3,4-dimethyldiphenyl sulfone

[0068] First, take 0.3 mmol of 3,4-dimethylphenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate and use 6 mL of MeCN as a solvent. Add these components sequentially into a 25 mL sealed electrolytic cell.

[0069] Use a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, use oxygen as the oxygen source, and perform sealed electrolysis and stirring at room temperature (current intensity I = 6 mA). The reaction lasts for 24 hours. After the reaction is completed, take out the sample and detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product 3,4-dimethyldiphenyl sulfone with a yield of 87%.

[0070] The 1H NMR characterization of 3,4-dimethyldiphenyl sulfone is as follows: 1 H NMR(400MHz,Chloroform-d)δ2.22(d,J=2.3Hz,6H),7.17(d,J=7.8Hz,1H),7.42(m,3H),7.60(m,2H),7.85(m,2H).

[0071] The 13C NMR characterization of 3,4-dimethyldiphenyl sulfone is as follows: 1313C NMR (101 MHz, Chloroform-d) δ 19.8, 19.9, 125.3, 127.5, 128.45, 129.2, 130.5, 132.9, 138.2, 138.7, 142.2, 142.8.

[0072] The reaction equation is as follows:

[0073]

[0074] Example 6: Preparation of 4-Phenyldiphenyl Sulfone

[0075] First, take 0.3 mmol of 4-phenylphenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate, and use 6 mL of MeCN as a solvent. Add these components sequentially into a 25 mL sealed electrolytic cell.

[0076] Use a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, use oxygen as the oxygen source, and conduct sealed electrolytic stirring at room temperature (current intensity I = 6 mA), and the reaction lasts for 24 hours. After the reaction is completed, take out the sample and detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product 4-phenyldiphenyl sulfone with a yield of 87%.

[0077] The 1H NMR characterization of 4-phenyldiphenyl sulfone is as follows: 1 1H NMR (400 MHz, Chloroform-d) δ 7.58 (m, 8H), 7.68 (d, J = 8.0 Hz, 2H), 8.09 (t, J = 7.7 Hz, 4H).

[0078] The 13C NMR characterization of 4-phenyldiphenyl sulfone is as follows: 13 13C NMR (101 MHz, Chloroform-d) δ 127.3, 127.6, 128.1, 128.1, 128.7, 129.0, 129.4, 133.4, 139.3, 140.2, 141.8, 146.3.

[0079] The reaction equation is as follows:

[0080]

[0081] Example 7: Preparation of 4,4'-Dimethoxydiphenyl Sulfone

[0082] First, take 0.3 mmol of 4-methoxyphenylhydrazine hydrochloride and 0.6 mmol of sodium 4-methoxybenzenesulfinate, then add 10 mol% of anhydrous NiBr 2 as the catalyst, and 20 mol% of 4-cyanopyridine as the ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate and use 6 mL of MeCN as the solvent. Add these components successively into a 25 mL sealed electrolytic cell.

[0083] Use a graphite felt electrode as the anode and a platinum plate electrode as the cathode, use oxygen as the oxygen source, carry out sealed electrolytic stirring at room temperature (current intensity I = 6 mA), and the reaction lasts for 24 hours. After the reaction is completed, take out the sample to detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product 4,4′-dimethoxydiphenyl sulfone with a yield of 91%.

[0084] The 1H NMR characterization of 4,4′-dimethoxydiphenyl sulfone is as follows: 1 H NMR(400MHz,DMSO-d6)δ2.41(s,3H),3.88(s,3H),7.17(m,2H),7.45(m,2H),7.86(m,2H),7.89(m,2H).

[0085] The 13C NMR characterization of 4,4′-dimethoxydiphenyl sulfone is as follows: 13 C NMR(101MHz,Chloroform-d)δ21.5,55.5,114.4,127.4,129.7,129.8,133.5,139.5,143.7,163.3.

[0086] The reaction equation is as follows:

[0087]

[0088] Example 8: Preparation of 4-ethoxydiphenyl sulfone

[0089] First, take 0.3 mmol of (4-ethoxyphenyl)hydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then add 10 mol% of anhydrous NiBr 2 as the catalyst, and 20 mol% of 4-cyanopyridine as the ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate and use 6 mL of MeCN as the solvent. Add these components successively into a 25 mL sealed electrolytic cell.

[0090] Using a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, with oxygen as the oxygen source, sealed electrolysis and stirring were carried out at room temperature (current intensity I = 6 mA), and the reaction continued for 24 hours. After the reaction was completed, the sample was taken out and the final product was detected by thin layer chromatography (TCL), and further separated and purified by column chromatography to obtain the final product 4-ethoxydiphenyl sulfone with a yield of 93%.

[0091] The 1H NMR characterization of 4-ethoxydiphenyl sulfone is as follows: 1 H NMR(400MHz,Chloroform-d)δ1.40(t,J=7.1Hz,3H),4.05(q,J=7.1Hz,2H),6.93(d,J=6.7Hz,2H),7.49(m,3H),7.89(m,4H).

[0092] The 13C NMR characterization of 4-ethoxydiphenyl sulfone is as follows: 13 C NMR(101MHz,Chloroform-d)δ14.7,64.1,114.8,127.4,129.1,129.8,132.7,142.5,162.9.

[0093] The reaction equation is as follows:

[0094]

[0095] Example 9: 4-trifluoromethoxydiphenyl sulfone

[0096] First, 0.3 mmol of 4-trifluoromethoxyphenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate were taken, and then 10 mol% of anhydrous NiBr 2 was used as the catalyst, and 20 mol% of 4-cyanopyridine was used as the ligand. Then 1 mmol of tetrabutylammonium tetrafluoroborate was added, and 6 mL of MeCN was used as the solvent. These components were successively added to a 25 mL sealed electrolytic cell.

[0097] Using a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, with oxygen as the oxygen source, sealed electrolysis and stirring were carried out at room temperature (current intensity I = 6 mA), and the reaction continued for 24 hours. After the reaction was completed, the sample was taken out and the final product was detected by thin layer chromatography (TCL), and further separated and purified by column chromatography to obtain the final product 4-trifluoromethoxydiphenyl sulfone with a yield of 95%.

[0098] The 1H NMR characterization of 4-(trifluoromethoxy)diphenyl sulfone is as follows: 1H NMR (400 MHz, Chloroform-d) δ 7.35 (m, 2H), 7.54 (m, 2H), 7.59 (m, 1H), 7.96 (m, 2H), 7.99 (m, 2H).

[0099] The 13C NMR characterization of 4-(trifluoromethoxy)diphenyl sulfone is as follows: 13 C NMR (101 MHz, Chloroform-d) δ 118.8, 121.2, 121.4, 127.7, 129.6, 129.8, 133.6, 140.1, 141.2, 152.4.

[0100] The reaction equation is as follows:

[0101]

[0102] Example 10: 4-Phenoxydiphenyl sulfone

[0103] First, take 0.3 mmol of 4-phenoxyphenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then add 10 mol% of anhydrous NiBr 2 as the catalyst, and 20 mol% of 4-cyanopyridine as the ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate, and use 6 mL of MeCN as the solvent. Add these components sequentially to a 25 mL sealed electrolytic cell.

[0104] Use a graphite felt electrode as the anode and a platinum plate electrode as the cathode, use oxygen as the oxygen source, and carry out sealed electrolytic stirring at room temperature (current intensity I = 6 mA), and the reaction lasts for 24 hours. After the reaction is completed, take out the sample and detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product 4-phenoxydiphenyl sulfone with a yield of 95%.

[0105] The 1H NMR characterization of 4-phenoxydiphenyl sulfone is as follows: 1 H NMR (400 MHz, Chloroform-d) δ 6.96 (m, 4H), 7.14 (t, J = 7.4 Hz, 1H), 7.32 (t, J = 7.8 Hz, 2H), 7.43 (t, J = 7.2 Hz, 2H), 7.47–7.52 (m, 1H), 7.81 (d, J = 8.7 Hz, 2H), 7.84–7.90 (m, 2H).

[0106] The 13C NMR characterization of 4-phenoxydiphenyl sulfone is as follows: 1313C NMR (101 MHz, Chloroform-d) δ 117.7, 120.4, 125.1, 127.5, 129.3, 130.0, 130.2, 133.0, 135.0, 142.0, 154.9, 162.1.

[0107] The reaction equation is as follows:

[0108]

[0109] Example 11: Preparation of 4-(methylthio)diphenyl sulfone

[0110] First, take 0.3 mmol of 4-(methylthio)phenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate, and use 6 mL of MeCN as a solvent. Add these components sequentially to a 25 mL sealed electrolytic cell.

[0111] Use a graphite felt electrode as the anode and a platinum plate electrode as the cathode, use oxygen as the oxygen source, and conduct sealed electrolysis and stirring at room temperature (current intensity I = 6 mA), and the reaction lasts for 24 hours. After the reaction is completed, take out the sample and detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product 4-(methylthio)diphenyl sulfone with a yield of 78%.

[0112] The 1H NMR characterization of 4-(methylthio)diphenyl sulfone is as follows: 1 1H NMR (400 MHz, Chloroform-d) δ 2.52 (s, 3H), 7.32 (d, J = 8.4 Hz, 2H), 7.45 (t, J = 7.3 Hz, 2H), 7.52 (t, J = 7.2 Hz, 1H), 7.88 (d, J = 8.4 Hz, 2H), 7.89 (d, J = 7.4 Hz, 2H).

[0113] The 13C NMR characterization of 4-(methylthio)diphenyl sulfone is as follows: 13 13C NMR (101 MHz, Chloroform-d) δ 14.7, 125.5, 127.4, 128.0, 129.3, 133.1, 137.1, 141.9, 146.7.

[0114] The reaction equation is as follows:

[0115]

[0116] Example 12: Preparation of 4-(ethylthio)diphenyl sulfone

[0117] First, take 0.3 mmol of 4-ethylthiophenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate and use 6 mL of MeCN as a solvent. Add these components into a 25 mL sealed electrolytic cell in sequence.

[0118] Use a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, use oxygen as the oxygen source, carry out sealed electrolytic stirring (current intensity I = 6 mA) at room temperature, and the reaction lasts for 24 hours. After the reaction is completed, take out the sample to detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product 4-ethylthiodiphenyl sulfone with a yield of 73%.

[0119] The 1H NMR characterization of 4-ethylthiodiphenyl sulfone is as follows: 1 H NMR (400 MHz, Chloroform-d) δ 1.27 (m, 3H), 2.91 (q, J = 7.4 Hz, 2H), 7.23 (d, J = 8.3 Hz, 2H), 7.36 - 7.53 (m, 3H), 7.73 (d, J = 8.2 Hz, 2H), 7.80–7.99 (m, 2H).

[0120] The 13C NMR characterization of 4-ethylthiodiphenyl sulfone is as follows: 13 C NMR (101 MHz, Chloroform-d) δ 13.8, 26.0, 126.6, 127.5, 128.0, 129.3, 133.1, 137.4, 141.8, 145.5.

[0121] The reaction equation is as follows:

[0122]

[0123] Example 13: Preparation of 4-methyldiphenyl sulfone

[0124] First, take 0.3 mmol of phenylhydrazine hydrochloride and 0.6 mmol of p-toluenesulfinate sodium, then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate and use 6 mL of MeCN as a solvent. Add these components into a 25 mL sealed electrolytic cell in sequence.

[0125] Using a graphite felt electrode as the anode, a platinum sheet electrode as the cathode, and oxygen as the oxygen source, a sealed electrolytic stirring was carried out at room temperature (current intensity I = 6 mA), and the reaction continued for 24 hours. After the reaction was completed, the sample was taken out and the final product was detected by thin layer chromatography (TCL), and further separated and purified by column chromatography to obtain the final product 4-methyl diphenyl sulfone with a yield of 98%.

[0126] Figure 5 This is the 1H NMR spectrum of 4-methyl diphenyl sulfone in Example 13. The 1H NMR characterization of 4-methyl diphenyl sulfone is as follows: 1 H NMR(400MHz,CDCl 3 )δ8.04–7.95(m,2H),7.70(d,J=8.1Hz,1H),7.62–7.53(m,1H),7.57–7.36(m,3H).

[0127] Figure 6 This is the 13C NMR spectrum of 4-methyl diphenyl sulfone in Example 13. The 13C NMR characterization of 4-methyl diphenyl sulfone is as follows: 13 C NMR(101MHz,CDCl 3 )δ146.21,141.78,140.15,139.20,133.19,129.32,129.06,128.60,128.22,127.95,127.67,127.36.

[0128] The reaction equation is as follows:

[0129]

[0130] Example 14: Preparation of 2-naphthyl phenyl sulfone

[0132] First, take 0.3 mmol of 2-naphthylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate, and use 6 mL of MeCN as a solvent. These components were sequentially added to a 25 mL sealed electrolytic cell.

[0133] Using a graphite felt electrode as the anode, a platinum sheet electrode as the cathode, and oxygen as the oxygen source, a sealed electrolytic stirring was carried out at room temperature (current intensity I = 6 mA), and the reaction continued for 24 hours. After the reaction was completed, the sample was taken out and the final product was detected by thin layer chromatography (TCL), and further separated and purified by column chromatography to obtain the final product 2-naphthyl phenyl sulfone with a yield of 90%.

[0134] The 1H NMR characterization of 2-naphthyl phenyl sulfone is as follows: 1 H NMR(400MHz,Chloroform-d)δ7.47–7.57(m,3H),7.63(m,2H),7.93(d,J=8.7Hz,1H),7.97–8.03(m,3H),8.58(d,J=1.9Hz,1H).

[0135] The 13C NMR characterization of 2-naphthyl phenyl sulfone is as follows: 13 C NMR(101MHz,Chloroform-d)δ122.7,127.7,127.7,127.9,129.1,129.2,129.3,129.4,129.7,132.2,133.2,135.0,138.4,141.7.

[0136] The reaction equation is as follows:

[0137]

[0138] Example 15: Preparation of m-chlorophenyl phenyl sulfone

[0139] First, take 0.3 mmol of 3-chlorophenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate, and use 6 mL of MeCN as a solvent. Add these components sequentially to a 25 mL sealed electrolytic cell.

[0140] Using a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, with oxygen as the oxygen source, perform sealed electrolytic stirring at room temperature (current intensity I = 6 mA), and the reaction lasts for 24 hours. After the reaction is completed, take out the sample and detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product m-chlorophenyl phenyl sulfone with a yield of 93%.

[0141] The 1H NMR characterization of m-chlorophenyl phenyl sulfone is as follows: 1 H NMR(400MHz,Chloroform-d)δ7.93(dd,J=7.4,1.8Hz,2H),7.91–7.84(m,2H),7.61–7.52(m,2H),7.52–7.44(m,3H).

[0142] The 13C NMR characterization of m-chlorophenyl phenyl sulfone is as follows: 13C NMR (101 MHz, Chloroform-d) δ 141.22, 140.15, 139.93, 133.46, 129.64, 129.43, 129.15, 127.67.

[0143] The reaction equation is as follows:

[0144]

[0145] Example 16: Preparation of 1-[(4-methylphenyl)sulfonyl]-4-(trifluoromethyl)benzene

[0146] First, take 0.3 mmol of 4-trifluoromethylphenylhydrazine hydrochloride and 0.6 mmol of sodium p-toluenesulfinate, then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate, and use 6 mL of MeCN as a solvent. Add these components successively to a 25 mL sealed electrolytic cell.

[0147] Using a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, with oxygen as the oxygen source, carry out sealed electrolytic stirring at room temperature (current intensity I = 6 mA), and the reaction lasts for 24 hours. After the reaction is completed, take out the sample and detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product 1-[(4-methylphenyl)sulfonyl]-4-(trifluoromethyl)benzene with a yield of 92%.

[0148] The 1H NMR characterization of 1-[(4-methylphenyl)sulfonyl]-4-(trifluoromethyl)benzene is as follows: 1 H NMR (400 MHz, Chloroform-d) δ 2.46 (s, 3H), 7.33 (d, J = 8.2 Hz, 2H), 7.74 (d, J = 8.2 Hz, 2H), 7.88 (d, J = 8.2 Hz, 2H), 8.24 (d, J = 8.2 Hz, 2H).

[0149] The 13C NMR characterization of 1-[(4-methylphenyl)sulfonyl]-4-(trifluoromethyl)benzene is as follows: 13 C NMR (101 MHz, Chloroform-d) δ 21.5, 123.2, 126.4, 128.1, 128.3, 130.8, 134.5, 137.6, 145.0, 145.6.

[0150] The reaction equation is as follows:

[0151]

[0152] Example 17: Preparation of 4-Cyanodiphenyl Sulfone

[0153] First, take 0.3 mmol of 4-cyanophenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, and then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate, and use 6 mL of MeCN as a solvent. Add these components sequentially into a 25 mL sealed electrolytic cell.

[0154] Use a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, use oxygen as the oxygen source, and carry out sealed electrolytic stirring at room temperature (current intensity I = 6 mA), and the reaction lasts for 24 hours. After the reaction is completed, take out the sample and detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product 4-cyanodiphenyl sulfone with a yield of 96%.

[0155] The 1H NMR characterization of 4-cyanodiphenyl sulfone is as follows: 1 H NMR(400MHz,Chloroform-d)δ7.50(dd,J=8.3,6.9Hz,2H),7.68(m,1H),7.86(m,2H),7.95(m,2H),8.08(m,2H).

[0156] The 13C NMR characterization of 4-cyanodiphenyl sulfone is as follows: 13 C NMR(101MHz,Chloroform-d)δ116.8,117.1,128.0,128.4,129.8,133.2,134.1,140.0,145.8.

[0157] The reaction equation is as follows:

[0158]

[0159] Example 18: Preparation of 4-[(4-Methylphenyl)sulfonyl]benzonitrile

[0160] First, take 0.3 mmol of 4-cyanophenylhydrazine hydrochloride and 0.6 mmol of p-toluenesulfinate sodium, and then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate, and use 6 mL of MeCN as a solvent. Add these components sequentially into a 25 mL sealed electrolytic cell.

[0161] Using a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, with oxygen as the oxygen source, sealed electrolysis and stirring were carried out at room temperature (current intensity I = 6 mA), and the reaction continued for 24 hours. After the reaction was completed, the sample was taken out and the final product was detected by thin layer chromatography (TCL), and further separated and purified by column chromatography to obtain the final product 4-[(4-methylphenyl)sulfonyl]benzonitrile with a yield of 91%.

[0162] The 1H NMR characterization of 4-[(4-methylphenyl)sulfonyl]benzonitrile is as follows: 1 H NMR(400MHz,Chloroform-d)δ2.46(s,3H),7.35(d,J=8.1Hz,2H),7.79(m,4H),8.08(m,2H).

[0163] The 13C NMR characterization of 4-[(4-methylphenyl)sulfonyl]benzonitrile is as follows: 13 C NMR(101MHz,Chloroform-d)δ141.22,140.15,139.93,133.46,129.64,129.43,129.15,127.67.

[0164] The reaction equation is as follows:

[0165]

[0166] Example 19: Preparation of 4-nitrodiphenyl sulfone

[0167] First, 0.3 mmol of 4-nitrophenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate were taken, and then 10 mol% of anhydrous NiBr 2 was added as a catalyst, and 20 mol% of 4-cyanopyridine was used as a ligand. Then 1 mmol of tetrabutylammonium tetrafluoroborate was added, and 6 mL of MeCN was used as a solvent. These components were added to a 25 mL sealed electrolytic cell in sequence.

[0168] Using a graphite felt electrode as the anode and a platinum sheet electrode as the cathode, with oxygen as the oxygen source, sealed electrolysis and stirring were carried out at room temperature (current intensity I = 6 mA), and the reaction continued for 24 hours. After the reaction was completed, the sample was taken out and the final product was detected by thin layer chromatography (TCL), and further separated and purified by column chromatography to obtain the final product 4-nitrodiphenyl sulfone with a yield of 94%.

[0169] Figure 7 This is the 1H NMR spectrum of 4-nitrodiphenyl sulfone in this example. The 1H NMR characterization of 4-nitrodiphenyl sulfone is as follows: 1 HNMR(400MHz,CDCl 3)δ8.38–8.30(m,2H),8.19–8.09(m,2H),8.02–7.94(m,2H),7.69–7.60(m,1H),7.56(dd,J=8.4,6.8Hz,2H).

[0170] Figure 8 This is the carbon-13 NMR spectrum of 4-nitrodiphenyl sulfone in this example. The carbon-13 NMR characterization of 4-nitrodiphenyl sulfone is as follows: 13 C NMR(101MHz,CDCl 3 )δ150.38,147.39,140.05,134.14,129.72,129.00,128.05,124.54.

[0171] The reaction equation is as follows:

[0172]

[0173] Example 20: Preparation of 4,4′-dinitrodiphenyl sulfone

[0174] First, take 0.3 mmol of 4-nitrophenylhydrazine hydrochloride and 0.6 mmol of sodium 4-nitrobenzenesulfinate, then add 10 mol% of anhydrous NiBr 2 as a catalyst, and 20 mol% of 4-cyanopyridine as a ligand. Then add 1 mmol of tetrabutylammonium tetrafluoroborate and use 6 mL of MeCN as a solvent. Add these components sequentially to a 25 mL sealed electrolytic cell.

[0175] Use a graphite felt electrode as the anode and a platinum plate electrode as the cathode, use oxygen as the oxygen source, and carry out sealed electrolysis and stirring at room temperature (current intensity I = 6 mA), and the reaction lasts for 24 hours. After the reaction is completed, take out the sample and detect the final product by thin layer chromatography (TCL), and further separate and purify it by column chromatography to obtain the final product 4,4′-dinitrodiphenyl sulfone with a yield of 86%.

[0176] The proton nuclear magnetic resonance characterization of 4,4′-dinitrodiphenyl sulfone is as follows: 1 H NMR(400MHz,Chloroform-d)δ2.48(s,3H),7.33(d,J=8.2Hz,2H),7.89(m,2H),8.20(m,2H),8.39(m,2H).

[0177] The carbon-13 NMR characterization of 4,4′-dinitrodiphenyl sulfone is as follows: 1313C NMR (101 MHz, Chloroform-d) δ 21.6, 124.7, 128.8, 129.1, 130.6, 137.2, 145.3, 147.6, 150.8.

[0178] The reaction equation is as follows:

[0179]

[0180] Example 21: Optimization of reaction conditions

[0181] 1. Optimization of solvent

[0182] First, take 0.3 mmol of phenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then take 10 mol% of the catalyst anhydrous NiBr 2 and 20 mol% of the ligand 4-cyanopyridine, then take 1 mmol of tetrabutylammonium tetrafluoroborate, add 6 mL of solvent, and successively add them to a 25 mL sealed electrolytic cell. Use a graphite felt electrode as the anode, a platinum plate electrode as the cathode, and oxygen as the oxygen source. Stir while sealing and energizing (I = 6 mA) at room temperature for 24 h. After the reaction is completed, take it out for TCL detection of the final product, and finally obtain the final product diphenyl sulfone by column chromatography. Under different solvent conditions, the yields of the final product diphenyl sulfone are as follows:

[0183] Table 1 Yields of diphenyl sulfone under different solvent conditions

[0184] Serial number Solvent Yield (%) 1 DMSO 34 2 THF 52 3 MeCN 86 4 DMF 31

[0185] The above results show that under different solvent conditions, the product can be obtained. However, when using DMSO, THF, and DMF as solvents, the yields are 34%, 52%, and 31% respectively, all lower than the yield of diphenyl sulfone when using MeCN as the solvent. Therefore, for the substrates phenylhydrazine hydrochloride and sodium benzenesulfinate, MeCN is the optimal solvent.

[0186] 2. Optimization of electrolyte

[0187] First, take 0.3 mmol of phenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then take 10 mol% of the catalyst anhydrous NiBr 2 and 20 mol% of the ligand 4-cyanopyridine, then take 1 mmol of electrolyte, add 6 mL of MeCN solvent, and successively add them to a 25 mL sealed electrolytic cell. Use a graphite felt electrode as the anode, a platinum plate electrode as the cathode, and oxygen as the oxygen source. Stir while sealing and energizing (I = 6 mA) at room temperature for 24 h. After the reaction is completed, take it out for TCL detection of the final product, and finally obtain the final product diphenyl sulfone by column chromatography. Under different electrolyte conditions, the yields of the product diphenyl sulfone are as follows:

[0188] Table 2 Yields of diphenyl sulfone under different electrolyte conditions

[0189]

[0190]

[0191] The above results show that the product can be obtained under different electrolyte conditions. For the substrates phenylhydrazine hydrochloride and sodium benzenesulfinate, tetrabutylammonium tetrafluoroborate is the optimal electrolyte.

[0192] 3. Optimization of ligands

[0193] First, take 0.3 mmol of phenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate, then take 10 mol% of the catalyst anhydrous NiBr 2 and 20 mol% of the ligand, then take 1 mmol of tetrabutylammonium tetrafluoroborate, add 6 mL of MeCN solvent, and successively add them into a 25 mL sealed electrolytic cell. A graphite felt electrode is used as the anode, a platinum plate electrode is used as the cathode, and oxygen is used as the oxygen source. Stir the reaction under sealed conditions and electrify (I = 6 mA) at room temperature for 24 h. After the reaction is completed, take out the product for TCL detection of the final product, and finally obtain the final product diphenyl sulfone by column chromatography. Under different electrolyte conditions, the yields of the product diphenyl sulfone are as follows:

[0194] Table 3 Yields of diphenyl sulfone under different ligand conditions

[0195] Serial number Ligand Yield (%) 1 4-Cyanopyridine 86 2 (S)-3,3'-Diphenyl-1,1'-binaphthyl-2,2'-diol 32 3 (1S,2S)-Cyclohexane-1,2-diamine 45 4 4,4',6,6'-Tetramethyl-2,2'-bipyridine 57 5 Phenanthroline 64 6 2,2'-Bipyrazine 55

[0196] The above results show that for the substrates phenylhydrazine hydrochloride and sodium benzenesulfinate, 4-cyanopyridine is the optimal ligand.

[0197] 4. Optimization of the ratio

[0198] First, take phenylhydrazine hydrochloride and sodium benzenesulfinate, then take 10 mol% of the catalyst anhydrous NiBr 2 and 20 mol% of the ligand 4-cyanopyridine, then take 1 mmol of tetrabutylammonium tetrafluoroborate, add 6 mL of MeCN solvent, and successively add them into a 25 mL sealed electrolytic cell. A graphite felt electrode is used as the anode, a platinum plate electrode is used as the cathode, and oxygen is used as the oxygen source. Stir the reaction under sealed conditions and electrify (I = 6 mA) at room temperature for 24 h. After the reaction is completed, take out the product for TCL detection of the final product, and finally obtain the final product diphenyl sulfone by column chromatography. Under different electrolyte conditions, the yields of the product diphenyl sulfone are as follows:

[0199] Table 4 Yields of diphenyl sulfone under different ratio conditions

[0200]

[0201]

[0202] The above results show that for the substrates phenylhydrazine hydrochloride and sodium benzenesulfinate, a 1:2 ratio is the optimal reactant ratio.

[0203] 5. Optimization of the catalyst

[0204] First, take 0.3 mmol of phenylhydrazine hydrochloride and 0.6 mmol of sodium benzenesulfinate. Then, take 10 mol% of the catalyst and 20 mol% of the ligand 4-cyanopyridine. Next, take 1 mmol of tetrabutylammonium tetrafluoroborate and add it to 6 mL of MeCN solvent. Then, add them successively to a 25 mL sealed electrolytic cell. Use a graphite felt electrode as the anode, a platinum plate electrode as the cathode, and oxygen as the oxygen source. Stir the reaction under sealed and energized conditions (I = 6 mA) at room temperature for 24 h. After the reaction is completed, take out the product for TLC detection of the final product. Finally, separate the final product diphenyl sulfone by column chromatography. Under different electrolyte conditions, the yields of the product diphenyl sulfone are as follows:

[0205] Table 4 Yields of diphenyl sulfone under different ratio conditions

[0206] Serial number Catalyst Yield (%) 1 Nickel(II) bromide anhydrous 86 2 Nickel(II) chloride anhydrous 66 3 Nickel(II) iodide anhydrous 74 4 Dibromo-bis(pyridine)nickel(II) 48 5 Nickel(II) chloride ethylene glycol dimethyl ether complex 81

[0207] The above results show that for the substrates phenylhydrazine hydrochloride and sodium benzenesulfinate, nickel bromide anhydrous is the optimal catalyst.

[0208] The present invention is different from the traditional heating or blue light reaction conditions. The reaction can be realized under mild reaction conditions of normal temperature and pressure by using electrocatalytic technology, with high yield and high selectivity, and does not need to occur under high temperature or light irradiation. This method solves the problem of realizing oxidative radical coupling under mild conditions, provides extremely high atom economy, enhances the adaptability to various functional groups and the yield of aryl sulfone compounds, and is an economical and efficient synthesis method.

[0209] The above is only the preferred embodiment of the present invention, and does not limit the scope of implementation of the present invention. Therefore, any equivalent changes or modifications made according to the structural features and principles described in the present invention, as well as the addition or replacement of conventional techniques in the art (such as the adjustment of reaction time and the addition amount of solvent, which are not the research focus of the present invention), should be included within the protection scope of the present invention.

Claims

1. A method for electrocatalytic synthesis of aryl sulfone compounds, characterized in that: Using phenylhydrazine hydrochloride and sodium arylsulfinate as raw materials, aryl sulfone compounds are synthesized through oxidative free radical coupling using electrocatalytic technology.

2. The electrocatalytic synthesis method of aryl sulfone compounds according to claim 1, characterized in that: The process includes: Step S1, taking phenylhydrazine hydrochloride and sodium arylsulfinate, a catalyst and a ligand, adding them into a sealed electrolytic cell in sequence, and then adding an electrolyte and a solvent; Step S2, using a graphite felt electrode as an anode, a platinum sheet electrode as a cathode, and oxygen as an oxidation source, the mixture is sealed and stirred at room temperature to perform a synthesis reaction; the reaction equation is: Wherein, R1 and R2 are hydrogen, electron donating groups or electron withdrawing groups; Step S3, after the reaction is completed, the final product is taken out and separated by column chromatography to obtain an aryl sulfone compound.

3. The electrocatalytic synthesis method of aryl sulfone compounds according to claim 2, characterized in that: The ligand is 4-cyanopyridine, (S)-3,3'-diphenylbinaphthol, (1S,2S)-cyclohexane-1,2-diamine, 4,4',6,6'-tetramethyl-2,2'-bipyridine, phenanthroline or 2,2'-bipyrazine.

4. The electrocatalytic synthesis method of aryl sulfone compounds according to claim 2, characterized in that: The electrolyte is tetrabutylammonium bromide, tetrabutylammonium tetrafluoroborate, tetrabutylammonium perchlorate or tetrabutylammonium iodide; and the solvent is dimethyl sulfoxide, acetonitrile, tetrahydrofuran or N,N-dimethylformamide.

5. The electrocatalytic synthesis method of aryl sulfone compounds according to claim 2, characterized in that: The catalyst is anhydrous nickel bromide, anhydrous nickel chloride, anhydrous nickel iodide, dibromobis(pyridine)nickel or nickel(II) chloride ethylene glycol dimethyl ether complex.

6. The electrocatalytic synthesis method of aryl sulfone compounds according to any one of claims 2 to 5, characterized in that: In step S1, the molar ratio of phenylhydrazine hydrochloride to sodium arylsulfite is 1:1-3; the amount of solvent added is 6 mL of solvent per 0.3 mmol of phenylhydrazine hydrochloride.

7. The electrocatalytic synthesis method of aryl sulfone compounds according to claim 6, characterized in that: A nickel transition metal salt is used as a catalyst, the amount of the nickel transition metal salt added is 1 to 10 mol % of the phenylhydrazine hydrochloride, and the amount of the ligand added is 1 to 20 mol % of the phenylhydrazine hydrochloride.

8. The electrocatalytic synthesis method of aryl sulfone compounds according to claim 6, characterized in that: With anhydrous acetonitrile as solvent, tetrabutyl fluoroborate as electrolyte, nickel transition metal salt as catalyst, and 4-cyanopyridine as ligand, the reaction equation for synthesizing aromatic sulfone compounds by oxidative free radical coupling under electrocatalytic technology is as follows: 。 9. The electrocatalytic synthesis method of aryl sulfone compounds according to claim 2, 3, 4, 5, 7 or 8, characterized in that: The R1 and R2 are electron-donating groups, such as methyl, methoxy, ethyl, ethoxy, isopropyl, tert-butyl, methylthio, phenyl, alkoxy or amino; R1 and R2 may be electron-withdrawing groups, such as nitro, cyano, trifluoromethyl, sulfonic acid, aldehyde, chlorine, fluorine or acyl.

10. The electrocatalytic synthesis method of aryl sulfone compounds according to claim 9, characterized in that: In step S2, the electrolysis current intensity is 6 mA and the reaction time is 12-48 hours.

Images