A preparation method of diphenyl sulfide compound

Abstract

A preparation method of a diphenyl sulfide compound relates to a preparation method of a compound. The invention comprises the following steps: adding a phenyl halide, a sulfur source, a copper salt, a Schiff base ligand and a base into an organic solvent, controlling the temperature between room temperature and 100°C, and reacting for 4 to 18 hours under magnetic stirring conditions; after the reaction is completed, cooling the reaction solution to room temperature, adding water and ethyl acetate into the reaction mixture, extracting the reaction product with ethyl acetate, and distilling off the solvent to obtain the diphenyl sulfide compound; further purifying the product by a chromatography column; the reaction substrate is a phenyl halide, and the structure thereof is shown in formula (I); wherein X is F, Cl, Br and I, and R is H, C n H 2n+1 , OC n H 2n+1 、X、CHO、CN、NO2、C n H 2n+1 1~3 substituents in CO and heterocyclic rings, etc. (n=1~8); the catalyst prepared by this method has low cost, mild reaction conditions, simple reaction process and easy separation of products.

Description

Technical Field

[0001] The invention relates to a method for preparing a compound by biomass conversion, and in particular to a method for preparing a diphenyl sulfide compound. Background Art

[0002] Diaryl sulfides and their derivatives play an important role in intermediates, organic synthesis, medicinal chemistry and bioactive molecules, and are also widely used in the treatment of diseases such as AIDS, cancer, Parkinson's disease, diabetes and Alzheimer's disease. The cross-coupling reaction of aryl halides and thiols catalyzed by transition metals is the main method for preparing diaryl sulfides. The main limitation of this method is the use of volatile and unpleasant odor thiols, which leads to inevitable environmental and safety problems. At the same time, since thiols tend to bind to transition metals, they are easy to deactivate transition metal catalysts. Moreover, during the reaction, thiols are prone to oxidative coupling side reactions with disulfides, which reduces the product yield. In addition, this method also has the disadvantages of difficult preparation and recovery of catalysts, high reaction temperature, and the use of harmful organic solvents.

[0003] In order to overcome these shortcomings, researchers have developed different transition metal catalysts in recent years to prepare aryl sulfide with various sulfur sources other than mercaptans and aryl halides. For example, elemental sulfur and thiourea are used as sulfur sources and immobilized transition metal catalysts are used for reaction, but such methods still have problems such as high reaction temperature, expensive catalysts, and low product yields. In order to solve these problems, the present invention uses copper salts and Schiff base ligands as in-situ catalysts to prepare diphenyl sulfide under mild conditions. The catalyst of this method is cheap, easy to obtain and can be recycled, and a higher diphenyl sulfide yield can be obtained under milder reaction conditions. Summary of the invention

[0004] The present invention provides a method for preparing a diphenyl sulfide compound. The present invention uses copper salt and Schiff base ligand as in-situ catalysts, uses in-situ catalysts based on copper salt and different Schiff bases to carry out diphenyl sulfide synthesis reaction, and prepares diphenyl sulfide under mild conditions. The catalyst of the method is cheap, easy to obtain and can be recycled, and a higher diphenyl sulfide yield is obtained under relatively mild reaction conditions.

[0005] The technical solution adopted by the present invention is:

[0006] A preparation method of a diphenyl sulfide compound: phenyl halide, sulfur source, copper salt, Schiff base ligand and base are added to an organic solvent, the temperature is controlled at room temperature to 100°C, and the reaction is carried out under magnetic stirring for 4 to 18 hours. After the reaction is completed, the reaction solution is cooled to room temperature, water and ethyl acetate are added to the reaction mixture, the reaction product is extracted with ethyl acetate, and the solvent is evaporated to obtain the diphenyl sulfide compound. The product can be further purified by a chromatography column. The ethyl acetate and water in the reaction solution are evaporated, dried with anhydrous sodium sulfate, and can be recycled.

[0007] In the above-mentioned method for preparing a diphenyl sulfide compound, the reaction substrate is a phenyl halide, and its structure is shown in formula (I). Wherein X is F, Cl, Br and I, and R is H, C n H 2n+1 , OC n H 2n+1 、X、CHO、CN、NO2、C n H 2n+1 Substituents such as CO and heterocyclic ring. (n=1~8)

[0008]

[0009] In the above-mentioned method for preparing a diphenyl sulfide compound, the organic solvent is a polar solvent such as DMSO, DMF or DMAc, preferably DMSO.

[0010] In the above-mentioned method for preparing a diphenyl sulfide compound, the copper salt is one of inorganic salts such as CuCl2, CuCl, CuI2, CuI, Cu(OAc)2 and Cu(NO3)2, preferably CuCl2, CuI and Cu(OAc)2.

[0011] The above-mentioned method for preparing a diphenyl sulfide compound, the Schiff base is one of a salicylaldehyde Schiff base, an amino acid Schiff base, a guanidine Schiff base and a hydrazone Schiff base, the preferred Schiff base is a salicylaldehyde Schiff base, and the more preferred ligand is L5, whose structure is shown in the following formula.

[0012]

[0013] In the above-mentioned method for preparing a diphenyl sulfide compound, the amount of the metal copper salt catalyst used is 1 to 10 mol% of the reaction substrate phenyl halide, and the preferred amount of the metal copper salt catalyst used is 3 to 5 mol% of the phenyl halide.

[0014] In the above-mentioned method for preparing a diphenyl sulfide compound, the molar ratio of the copper salt to the Schiff base ligand is 1:1 to 1:6, and the preferred molar ratio of the copper salt to the Schiff base ligand is 1:1 to 1:2.

[0015] In the above-mentioned method for preparing a diphenyl sulfide compound, the sulfur source used in the reaction is one of sulfides such as elemental sulfur, thiourea, and thiocyanate, and the preferred sulfur source is elemental sulfur or thiourea.

[0016] In the above-mentioned method for preparing a diphenyl sulfide compound, the amount of the sulfur source is 0.4 to 0.6 times the amount of the reactant phenyl halide substance, and the preferred amount of the sulfur source is 0.5 times the amount of the reactant phenyl halide substance.

[0017] The above-mentioned method for preparing a diphenyl sulfide compound, the base is one of inorganic bases such as lithium carbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium hydroxide, rubidium carbonate, cesium carbonate, tert-butyl potassium, tert-butyl sodium, sodium acetate and sodium ethoxide, and the preferred base is sodium carbonate, potassium carbonate, potassium hydroxide and sodium ethoxide.

[0018] In the above-mentioned method for preparing a diphenyl sulfide compound, the amount of the base substance is 1 to 5 times that of the reaction substrate phenyl halide, and preferably the amount of the base substance is 1 to 3 times that of the reaction substrate phenyl halide.

[0019] In the above-mentioned method for preparing a diphenyl sulfide compound, the reaction temperature is room temperature to 100°C, and the preferred reaction temperature is 60 to 80°C.

[0020] In the above-mentioned method for preparing a diphenyl sulfide compound, the reaction time is 4 to 18 hours, and the preferred reaction time is 6 to 10 hours.

[0021] The beneficial effects of the present invention are:

[0022] The present invention is the first to use an in-situ catalyst based on copper salt and Schiff base ligand for the reaction of preparing diphenyl sulfide, which has low catalyst cost, good selectivity and mild reaction conditions; (2) by the method of the present invention, a cross-coupling reaction is carried out between a phenyl halide and a sulfur source to prepare a diphenyl sulfide compound, and the yield of the diphenyl sulfide compound is more than 90%; (3) the catalyst and product separation process is simple, the in-situ catalyst is easy to reuse and can be recycled for more than 10 times, which effectively reduces the catalyst preparation cost; (4) the in-situ catalyst, sulfur source and organic solvent used in the present invention have stable chemical properties and are environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a diagram showing the recycling status of the catalyst Cu(OAc)2 / L5 of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below by way of examples, but the examples are not intended to limit the present invention.

[0025] Example 1 Cu(OAc)2 / L5(n Cu :n L5 =1) Catalyze the reaction of iodobenzene and elemental sulfur to prepare diphenyl sulfide compounds

[0026] The structural formula of diphenyl sulfide prepared by the reaction of iodobenzene and elemental sulfur is shown below:

[0027]

[0028] Add iodobenzene (1 mmol), S8 (0.5 mmol), Cu(OAc)2 (0.05 mmol), ligand L5 (0.05 mmol), KOH (3 mmol) and DMSO (15 mL) to a 50 mL reaction bottle and react at 60 °C for 8 h. After the reaction, add 15 mL of distilled water to the reaction mixture, and then extract with ethyl acetate (30 mL × 2). Evaporate the ethyl acetate phase solution to obtain a crude product, which is purified by column chromatography to obtain the target product with a yield of 95%. Evaporate the water in the lower layer solution, dry it with anhydrous Na2SO4 and it can be recycled.

[0029] NMR data: 1 H NMR (CDCl3, 400MHz) d (ppm):7.34-7.30 (m, 4H), 7.30-7.25(m, 4H), 7.24-7.19(m, 2H). 13 C NMR (CDCl3, 125MHz) d (ppm): 135.58, 130.89,129.11, 127.11.

[0030] Example 2 Cu(OAc)2 / L5(n Cu :n L5 =1) Catalyze the reaction of 4-methyl iodobenzene with elemental sulfur to prepare diphenyl sulfide compounds

[0031] The structural formula of diphenyl sulfide compound prepared by the reaction of 4-methyl iodobenzene and elemental sulfur is shown below:

[0032]

[0033] 4-Methyliodobenzene (1 mmol), S8 (0.5 mmol), Cu(OAc)2 (0.05 mmol), ligand L5 (0.05 mmol), KOH (3 mmol) and DMSO (15 mL) were added to a 50 mL reaction bottle and reacted at 60 °C for 8 h. After the reaction, 15 mL of distilled water was added to the reaction mixture, and then extracted with ethyl acetate (30 mL × 2). The ethyl acetate phase solution was evaporated to obtain a crude product, which was purified by column chromatography to obtain the target product with a yield of 92%. The water in the lower layer solution was evaporated and dried over anhydrous Na2SO4 for recycling.

[0034] NMR data: 1 H NMR (CDCl3, 400MHz) d (ppm):7.26 (d, J = 8.2 Hz, 4H), 7.15(d, J = 7.9 Hz, 4H), 2.36 (s, 6H). 13 C NMR (CDCl3, 125MHz) d (ppm):136.72,132.45, 130.85, 129.75, 21.00.

[0035] Example 3 Cu(OAc)2 / L5 (n Cu :n L5 =1) Catalyze the reaction of 4-methoxyiodobenzene with elemental sulfur to prepare diphenyl sulfide compounds

[0036] The structural formula of diphenyl sulfide compound prepared by the reaction of 4-methoxyiodobenzene and elemental sulfur is shown below:

[0037]

[0038] 4-Methoxyiodobenzene (1 mmol), S8 (0.5 mmol), Cu(OAc)2 (0.05 mmol), ligand L5 (0.05 mmol), KOH (3 mmol) and DMSO (15 mL) were added to a 50 mL reaction bottle and reacted at 60 °C for 8 h. After the reaction, 15 mL of distilled water was added to the reaction mixture, and then extracted with ethyl acetate (30 mL × 2). The ethyl acetate phase solution was evaporated to obtain a crude product, which was purified by column chromatography to obtain the target product with a yield of 91%. The water in the lower layer solution was evaporated and dried over anhydrous Na2SO4 for recycling.

[0039] NMR data: 1 H NMR (CDCl3, 400MHz) d (ppm):7.32-7.30 (m, 1H), 7.31 - 7.29(m, 3H), 7.27 - 7.25 (m, 3H), 7.24-7.23 (m, 1H), 1.30 (s, 18H). 13 C NMR (CDCl3, 125MHz) d (ppm):150.01, 132.45, 130.56, 126.02, 34.36, 31.21.

[0040] Example 4 Cu(OAc)2 / L5 (n Cu :n L5 =1) Catalyze the reaction of 4-chloroiodobenzene with elemental sulfur to prepare diphenyl sulfide compounds

[0041] The structural formula of diphenyl sulfide compound prepared by the reaction of 4-chloroiodobenzene and elemental sulfur is shown below:

[0042]

[0043] 4-Chloroiodobenzene (1 mmol), S8 (0.5 mmol), Cu(OAc)2 (0.05 mmol), ligand L5 (0.05 mmol), KOH (3 mmol) and DMSO (15 mL) were added to a 50 mL reaction bottle and reacted at 60 °C for 8 h. After the reaction, 15 mL of distilled water was added to the reaction mixture, and then extracted with ethyl acetate (30 mL × 2). The ethyl acetate phase solution was evaporated to obtain a crude product, which was purified by column chromatography to obtain the target product with a yield of 98%. The water in the lower layer solution was evaporated and dried over anhydrous Na2SO4 before recycling.

[0044] NMR data: 1 H NMR (CDCl3, 400MHz) d (ppm):7.42-7.38 (m,4H), 7.37-7.33 13 CNMR (CDCl3, 125MHz) d (ppm):134.89, 133.91, 133.33, 130.28.

[0045] Example 5 Cu(OAc)2 / L5 (n Cu :n L5 =1) Catalyze the reaction of 3-chloroiodobenzene with elemental sulfur to prepare diphenyl sulfide compounds

[0046] The structural formula of diphenyl sulfide compound prepared by the reaction of 3-chloroiodobenzene and elemental sulfur is shown below:

[0047]

[0048] 3-Chloroiodobenzene (1 mmol), S8 (0.5 mmol), Cu(OAc)2 (0.05 mmol), ligand L5 (0.05 mmol), KOH (3 mmol) and DMSO (15 mL) were added to a 50 mL reaction bottle and reacted at 60 °C for 8 h. After the reaction, 15 mL of distilled water was added to the reaction mixture, and then extracted with ethyl acetate (30 mL × 2). The ethyl acetate phase solution was evaporated to obtain a crude product, which was purified by column chromatography to obtain the target product with a yield of 98%. The water in the lower layer solution was evaporated and dried over anhydrous Na2SO4 for recycling.

[0049] NMR data: 1 H NMR (CDCl3, 400MHz) d (ppm):7.35 (m,2H), 7.24-7.20. 13 C NMR (CDCl3, 125MHz) d (ppm):136.82, 135.19, 130.81, 130.32, 129.12, 127.75.

[0050] Example 6 Cu(OAc)2 / L5 (n Cu :n L5 =1) Catalyze the reaction of 2-chloroiodobenzene with elemental sulfur to prepare diphenyl sulfide compounds

[0051] The structural formula of diphenyl sulfide compound prepared by the reaction of 2-chloroiodobenzene and elemental sulfur is shown below:

[0052]

[0053] Add 2-chloroiodobenzene (1 mmol), S8 (0.5 mmol), Cu(OAc)2 (0.05 mmol), ligand L5 (0.05 mmol), KOH (3 mmol) and DMSO (15 mL) to a 50 mL reaction bottle and react at 60 °C for 8 h. After the reaction, add 15 mL of distilled water to the reaction mixture, and then extract with ethyl acetate (30 mL × 2). Evaporate the ethyl acetate phase solution to obtain a crude product, which is purified by column chromatography to obtain the target product with a yield of 96%. Evaporate the water in the lower layer solution, dry it with anhydrous Na2SO4 and it can be recycled.

[0054] NMR data:1 H NMR (CDCl3, 400MHz) d (ppm):77.43 (dd, J = 7.7, 1.5 Hz, 2H), 7.23-7.12 (m, 6H). 13 C NMR (CDCl3, 125MHz) d (ppm):135.51, 133.23, 132.34,130.11, 128.67, 127.53.

[0055] Example 7-12 Reaction of iodobenzene with elemental sulfur to prepare diphenyl sulfide compounds under different conditions

[0056] The structural formula of diphenyl sulfide prepared by the reaction of iodobenzene and elemental sulfur is shown below:

[0057]

[0058] Add iodobenzene (1 mmol), sulfur source, copper salt, ligand, base and solvent (15 mL) to a 50 mL reaction bottle and react at different temperatures for a certain time. After the reaction, add 15 mL of distilled water to the reaction mixture, and then extract with ethyl acetate (30 mL × 2). Evaporate the ethyl acetate phase solution to obtain a crude product, which is purified by column chromatography to obtain the target product. Evaporate the water in the lower layer solution, dry it with anhydrous Na2SO4 and it can be recycled. The experimental results are shown in Table 1.

[0059] Table 1 Optimization of reaction conditions

[0060]

[0061] Example 13 Catalyst Cu(OAc)2 / L5 (n Cu :n L5 =1) Recycle

[0062] Cu(OAc)2 / L5(n Cu :n L5=1) was used as a catalyst to react iodobenzene with S8: iodobenzene (1 mmol), S8 (0.5 mmol), Cu(OAc)2 (0.05 mmol), ligand L5 (0.05 mmol), KOH (3 mmol) and DMSO (15 mL) were added to a 50 mL reaction bottle and reacted at 60 °C for 8 h. After the reaction, 15 mL of distilled water was added to the reaction mixture, and then extracted with ethyl acetate (30 mL × 2). The ethyl acetate phase solution was evaporated to obtain a crude product, and the product was purified by column chromatography to obtain the target product, and quantitative calculation was performed to calculate the yield of diphenyl sulfide. The water in the lower layer solution was evaporated and dried with anhydrous Na2SO4 before recycling. The catalyst recycling situation is as follows Figure 1 As shown, after using it 10 times, a yield of more than 90% can still be obtained.

[0063] Comparative Example 1

[0064] Reaction of iodobenzene and S8 without catalyst: Add iodobenzene (1 mmol), S8 (0.5 mmol), KOH (3 mmol) and DMSO (15 mL) to a 50 mL reaction bottle and react at 60 °C for 8 h. After the reaction, add 15 mL of distilled water to the reaction mixture, and then extract with ethyl acetate (30 mL × 2). The ethyl acetate phase solution was evaporated to obtain a crude product, which was purified by column chromatography to obtain the target product. The yield of diphenyl sulfide was 5%.

[0065] Comparative Example 2

[0066] Reaction of iodobenzene and S8 with only Cu(OAc)2: Add iodobenzene (1 mmol), S8 (0.5 mmol), Cu(OAc)2 (0.05 mmol), KOH (3 mmol) and DMSO (15 mL) to a 50 mL reaction bottle and react at 60 °C for 8 h. After the reaction, add 15 mL of distilled water to the reaction mixture, and then extract with ethyl acetate (30 mL×2). The ethyl acetate phase solution was evaporated to obtain a crude product, which was purified by column chromatography to obtain the target product. The yield of diphenyl sulfide was 76%.

[0067] Comparative Example 3

[0068] Reaction of iodobenzene and S8 with only ligand L5: Add iodobenzene (1 mmol), S8 (0.5 mmol), ligand L5 (0.05 mmol), KOH (3 mmol) and DMSO (15 mL) to a 50 mL reaction bottle and react at 60 °C for 8 h. After the reaction, add 15 mL of distilled water to the reaction mixture, and then extract with ethyl acetate (30 mL × 2). The ethyl acetate phase solution was evaporated to obtain a crude product, which was purified by column chromatography to obtain the target product. The yield of diphenyl sulfide was 11%.

[0069] The above examples show that the preparation method of a diphenyl sulfide compound of the present invention can be used to prepare diphenyl sulfide compounds by using phenyl halide as a raw material, elemental sulfur or other sulfides as a sulfur source, a highly polar organic solvent as a reaction medium, and an in-situ catalyst composed of a Schiff base ligand and different copper salts. The process promotes the synthesis reaction of diphenyl sulfide with a cheap and readily available copper salt in-situ catalyst, and the ligand can improve the catalytic activity of the copper salt. The method has low catalyst synthesis cost, mild reaction conditions, simple reaction process, and easy product separation, providing a new process route for the synthesis of diaryl sulfide compounds, which are important pharmaceutical intermediates.

Claims

1. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol iodobenzene, 0.5mmol S8, 0.05mmol Cu(OAc)2, 0.05mmol L5, 3mmol KOH and 15mL DMSO into a 50mL reaction bottle, reacting at 60°C for 8h; adding 15mL distilled water to the reaction mixture after the reaction, and then extracting with 30mL×2 ethyl acetate; distilling out the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 95%; the product structural formula is: The L5 structure is:

2. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol 4-methyliodobenzene, 0.5mmol S8, 0.05mmol Cu(OAc)2, 0.05mmol ligand L5, 3mmol KOH and 15mL DMSO into a 50mL reaction bottle, reacting at 60°C for 8h, adding 15mL distilled water to the reaction mixture after the reaction is completed, and then extracting with 30mL×2 ethyl acetate; distilling out the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 92%; the product structural formula is: The L5 structure is:

3. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol 4-methoxyiodobenzene, 0.5mmol S8, 0.05mmol Cu(OAc)2, 0.05mmol ligand L5, 3mmol KOH and 15mL DMSO into a 50mL reaction bottle, reacting at 60°C for 8h; adding 15mL distilled water to the reaction mixture after the reaction is completed, and then extracting with 30mL×2 ethyl acetate; distilling off the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 91%; the product structural formula is: The L5 structure is:

4. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol 4-chloroiodobenzene, 0.5mmol S8, 0.05mmol Cu(OAc)2, 0.05mmol ligand L5, 3mmol KOH and 15mL DMSO into a 50mL reaction bottle, reacting at 60°C for 8h; adding 15mL distilled water to the reaction mixture after the reaction is completed, and then extracting with 30mL×2 ethyl acetate; distilling off the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 98%; the product structural formula is: The L5 structure is:

5. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol 3-chloroiodobenzene, 0.5mmol S8, 0.05mmol Cu(OAc)2, 0.05mmol ligand L5, 3mmol KOH and 15mL DMSO into a 50mL reaction bottle, reacting at 60°C for 8h; after the reaction, adding 15mL distilled water to the reaction mixture, and then extracting with 30mL×2 ethyl acetate; distilling off the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 98%; the product structural formula is: The L5 structure is:

6. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol 2-chloroiodobenzene, 0.5mmol S8, 0.05mmol Cu(OAc)2, 0.05mmol ligand L5, 3mmol KOH and 15mL DMSO into a 50mL reaction bottle, reacting at 60°C for 8h; after the reaction, adding 15mL distilled water to the reaction mixture, 30mL×2, and then extracting with ethyl acetate; distilling off the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 96%; the product structural formula is: The L5 structure is:

7. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol iodobenzene, 1mmol S8, 0.05mmol Cu(OAc)2, 0.1mmol ligand L5, 5mmol Na2CO3 and 15mL solvent into a 50mL reaction bottle, reacting at 60°C for 8h; adding 15mL distilled water to the reaction mixture after the reaction, and then extracting with 30mL×2 ethyl acetate; distilling out the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 93%; the structural formula is: The L5 structure is:

8. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol iodobenzene, 0.5mmol C(NH2)2S, 0.03mmol Cu(OAc)2, 0.03mmol ligand L5, 2mmol Na2CO3 and 15mL solvent into a 50mL reaction bottle, reacting at 60°C for 8h; adding 15mL distilled water to the reaction mixture after the reaction, and then extracting with 30mL×2 ethyl acetate; distilling off the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 88%; the structural formula is: The L5 structure is:

9. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol iodobenzene, 0.5mmol S8, 0.05mmol Cu(NO3)2, 0.05mmol ligand L2, 2mmol Na2CO3 and 15mL solvent into a 50mL reaction bottle, reacting at 60°C for 8h; adding 15mL distilled water to the reaction mixture after the reaction, and then extracting with 30mL×2 ethyl acetate; distilling out the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 85%; the structural formula is: The L2 structure is:

10. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol iodobenzene, 0.5mmol KSCN, 0.1mmol Cu(OAc)2, 0.2mmol ligand L1, 3mmol KOH / and 15mL solvent into a 50mL reaction bottle, reacting at 80°C for 6h; adding 15mL distilled water to the reaction mixture after the reaction, and then extracting with 30mL×2 ethyl acetate; distilling out the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 72%; the structural formula is: The L3 structure is:

11. A method for preparing a diphenyl sulfide compound, characterized in that: The method comprises the following steps: adding 1mmol iodobenzene, 1mmol C(NH2)2S, 0.1mmol CuI, 0.03mmol ligand L4, 5mmol K2CO3 / and 15mL solvent into a 50mL reaction bottle, reacting at 100°C for 6h; after the reaction is completed, adding 15mL distilled water to the reaction mixture, and then extracting with 30mL×2 ethyl acetate; distilling out the ethyl acetate phase solution to obtain a crude product, and purifying the product by column chromatography to obtain the target product with a yield of 69%; the structural formula is: The L4 structure is:

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