A method for the silver-catalyzed oxidation to prepare sulfoxides

Abstract

The present application relates to a kind of silver catalytic oxidation preparation sulfoxide method, first preparation is supported silver catalyst, under the action of this silver catalyst, catalytic hydrogen peroxide oxidation sulfide preparation sulfoxide.The silver catalyst prepared by this method has high stability and can be recycled multiple times.It catalyzes the oxidation of sulfide to obtain sulfoxide with high efficiency.Silver catalytic oxidation of sulfoxide reaction process has the advantages of high efficiency and high selectivity, and the catalyst is easy to recover, and is friendly to the environment.The product is easy to separate, and has good industrial application prospect.

Description

Technical Field

[0001] This invention relates to a method for preparing sulfoxide by oxidation; more particularly, it relates to a method for preparing sulfoxide by silver-catalyzed oxidation. Background Technology

[0002] Sulfoxides are not only commonly used solvents and extractants in organic synthesis experiments, but also widely used in the synthesis of various drugs, serving as important intermediates for pharmaceuticals, pesticides, and expensive materials. The selection of catalysts that can efficiently oxidize sulfides to sulfoxides has always been a hot topic in the field of synthesis. Currently, commonly used catalysts mainly include hydrogen peroxide, metal compounds, and halogen compounds.

[0003] Dimethyl sulfoxide (DMSO) is a sulfur-containing organic compound, a colorless and odorless transparent liquid at room temperature. It is an important organic solvent due to its high polarity, high hygroscopicity, flammability, and high-boiling-point aprotic properties. DMSO is soluble in water, ethanol, acetone, benzene, and chloroform. As a highly polar and inert solvent, it is widely used as a solvent and reaction reagent, earning it the reputation of a "universal solvent." For example, it is used as a processing solvent and spinning solvent in acrylonitrile polymerization, as a synthesis solvent and spinning solvent in polyurethane, and as a synthesis solvent for polyamides, chlorofluoroanilines, polyimides, and polysulfones. Furthermore, DMSO has high selective extraction capabilities and can be used as an extraction solvent for separating alkanes from aromatic hydrocarbons; for example, DMSO can be used for the extraction of aromatic hydrocarbons or butadiene. In the pharmaceutical industry, DMSO is also a permeability protectant, capable of lowering cell freezing points, reducing ice crystal formation, mitigating free radical damage to cells, and altering the permeability of biological membranes to electrolytes, drugs, toxins, and metabolites. In addition, dimethyl sulfoxide can also be used as a capacitor dielectric, antifreeze, brake fluid, and rare metal extractant.

[0004] Currently, the main method for producing dimethyl sulfoxide (DMSO) is through the oxidation of dimethyl sulfide. This method suffers from problems such as high reaction temperature, high energy consumption, long process flow, numerous byproducts, and safety concerns, while also causing significant environmental pollution. For example, Qian-You Wang et al. (Angew. Chem. Int. Ed. 2022, 61, e202207130(7 of 7)) utilized covalent organic frameworks (COFs) as photocatalysts for the oxidization of sulfides, synthesizing a novel crystalline, porous amino-linked porphyrin-based COF (Por-AminalCOF). Under light irradiation, the COF exhibited high catalytic efficiency in the oxidation of the sulfur mustard mimic CEES with a t1 / 2 of 5 minutes and 100% selectivity. However, the preparation process of this catalyst is complex and cannot be widely applied to industrial production. Kai Liu and Jiaolong Meng (Org. Process Res. Dev. 2023, 27, 1198-1202) et al. selectively oxidized sulfides to sulfoxides under mild conditions using Fe(NO3)3·9H2O as a catalyst and oxygen as an oxidant. This catalyst can oxidize sulfides to sulfoxides, but the yield of sulfoxides varies greatly under different reaction conditions, and a relatively high yield and selectivity can only be obtained under the condition of acetic acid as a solvent. The production cost is relatively high in industrial applications.

[0005] Chinese patent document CN116262715A reports a method in which sulfide and oxidant are brought into contact in the presence of nano-carbon-based materials and optional solvents to carry out an oxidation reaction, thereby obtaining an oxidation reaction product. However, the preparation of the nano-carbon-based materials used in this method is relatively complex, resulting in low production efficiency and high cost.

[0006] Chinese patent document CN117088794A discloses a method for preparing dimethyl sulfoxide, comprising the following steps: A) preheating and mixing hydrogen sulfide and methanol, then reacting them under the action of a first catalyst to obtain crude dimethyl sulfide; B) condensing and dehydrating the crude dimethyl sulfide obtained in the above step, followed by separation and purification steps to obtain high-purity dimethyl sulfide; C) oxidizing the high-purity dimethyl sulfide obtained in the above step, an oxidant, and a solvent under the action of a second catalyst to obtain crude dimethyl sulfoxide; D) evaporating, removing impurities, and separating and purifying the crude dimethyl sulfoxide obtained in the above step to obtain electronic-grade dimethyl sulfoxide. The dimethyl sulfide prepared by this invention has a purity greater than 99.99%. However, the method is relatively complex.

[0007] Chinese patent document CN202110026130.2 discloses a method for preparing methyl phenyl sulfoxide: using a polyoxometalate as a catalyst, it is placed in a reaction vessel, and an organic solvent and methyl phenyl ether are added sequentially to the vessel. Finally, an oxidant is added, and after heating and stirring, methyl phenyl sulfoxide is separated. After the reaction is complete, the polyoxometalate can be filtered out, processed, and recovered. The recovered polyoxometalate is then used for the oxidation reaction of methyl phenyl ether. However, this method has a long reaction time, reaching 24 hours, and requires a high temperature of 80°C. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing sulfoxide by silver catalytic oxidation in order to overcome the shortcomings of the prior art.

[0009] The technical solution of the present invention is as follows: a method for preparing sulfoxide by silver catalytic oxidation, the specific steps of which are as follows: a) Preparation of silver catalyst: silver nitrate and support are placed in a container, stirred thoroughly for 2-3 hours, potassium halide salt is added, stirring is continued for 1-2 hours, and then dried to obtain silver catalyst; wherein the silver halide salt accounts for 0.1% to 10% of the total mass of the prepared silver catalyst; b) Preparation of sulfoxide: sulfide is placed in a container, hydrogen peroxide and the silver catalyst prepared in step a) are added, the reaction temperature is controlled at 25-45℃, the reaction time is 3-20 hours, and sulfoxide is generated by silver catalyst catalysis, as shown in Formula 1.

[0010] The preferred mass ratio of silver nitrate to the carrier in step a is 1:(6.7-850); the mass ratio of silver nitrate to potassium halide salt is 1:(0.4-0.7).

[0011] The preferred carrier in step a is silicon oxide, aluminum oxide, or titanium oxide.

[0012] Preferably, the potassium halogen salt in step a is potassium chloride, potassium bromide, or potassium iodide.

[0013] The preferred step b involves adding a silver catalyst at a mass of 1.6%-8.5% of the sulfide mass.

[0014] The preferred ratio of the molar amount of hydrogen peroxide to the molar amount of sulfide in step b is 1:(1.0-1.1).

[0015] The sulfide in step b is preferably dimethyl sulfide or methyl phenyl sulfide; the sulfoxide product is preferably dimethyl sulfoxide or methyl phenyl sulfoxide.

[0016]

[0017] Beneficial effects:

[0018] This invention provides a method for preparing a silver catalyst and its oxidation to prepare sulfoxide. This method avoids the use of harmful gases, reducing production risks and environmental hazards. The catalyst is stable, efficient, and easy to separate. The process is simple, efficient, and operates under mild conditions with high selectivity, low risk, and easy product separation. The process requires minimal equipment, is inexpensive, and is suitable for industrial production. Detailed Implementation

[0019] Implementation Method 1: Preparation of AgCl / SiO2-10% catalyst. 10g of silver nitrate was dissolved in 1000ml of water until completely dissolved. Then, 67.73g of silicon dioxide was added, and the mixture was stirred for 2 hours to obtain a mixture. 6.57g of potassium chloride was added to the mixture, and stirring was continued for 2 hours to obtain another mixture. This mixture was then dried in an oven at 120℃ for 12 hours to obtain a silver chloride catalyst. The mass of silver chloride in the catalyst accounted for 10% of the total mass.

[0020] Example 2: Preparation of AgCl / SiO2-5% catalyst. The amount of silver nitrate added was changed to 10g, the amount of potassium chloride added was changed to 6.57g, and 152.03g of silicon dioxide was added. The remaining operations were performed as described in Example 1. A silver chloride catalyst was obtained, in which the mass of silver chloride accounted for 5% of the total mass.

[0021] Example 3: Preparation of AgCl / SiO2-1% catalyst. The amount of silver nitrate added was changed to 0.5g, the amount of potassium chloride added was changed to 0.219g, and 41.4g of silicon dioxide was added. The remaining operations were performed as described in Example 1. A silver chloride catalyst was obtained, in which the mass of silver chloride accounted for 1% of the total mass.

[0022] Example 4: Preparation of AgCl / SiO2 catalyst -0.1%. The amount of silver nitrate added was changed to 0.05 g, the amount of potassium chloride added was changed to 0.0219 g, and 41.42 g of silicon dioxide was added. The remaining operations were performed as described in Example 1. A silver chloride catalyst was obtained, in which the mass of silver chloride accounted for 0.1% of the total mass.

[0023] Implementation Method 5: Preparation of AgCl / Al3O2 catalyst -0.1%. 0.05 g of silver nitrate was dissolved in 1000 ml of water until completely dissolved. Then, 42.05 g of alumina was added, and the mixture was stirred for 3 hours to obtain mixture A. 0.0219 g of potassium chloride was added to the mixture, and the reaction was continued for 2 hours to obtain another mixture. This mixture was then dried in an oven at 120°C for 12 hours to obtain the silver chloride catalyst. The mass of silver chloride in the catalyst accounted for 0.1% of the total mass.

[0024] Implementation Method 6: Preparation of AgCl / TiO2 catalyst -0.1%. 0.05 g of silver nitrate was dissolved in 1000 ml of water until completely dissolved. Then, 42.05 g of titanium oxide was added and stirred until homogeneous, yielding a mixture. 0.0219 g of potassium chloride was added to the mixture, and the reaction was continued for 1 hour to obtain another mixture. This mixture was then dried in an oven at 120°C for 12 hours to obtain a silver chloride catalyst. The mass of silver chloride in the catalyst accounted for 0.1% of the total mass.

[0025] Example 7: Preparation of AgBr / TiO2 catalyst -0.1%. The amount of silver nitrate added was changed to 0.05 g, the amount of potassium bromide added was 0.035 g, and 42.04 g of silicon dioxide was added. The remaining operations were performed as described in Example 1. A silver bromide catalyst was obtained, in which the mass of silver bromide accounted for 0.1% of the total mass.

[0026] Example 8: Preparation of AgI / TiO2 catalyst -0.1%. The amount of silver nitrate added was changed to 0.1 g, potassium iodide was added to 0.049 g, and 42.03 g of silicon dioxide was added. The remaining operations were performed as described in Example 1. A silver iodide catalyst was obtained, in which the mass of silver iodide accounted for 0.1% of the total mass.

[0027] Implementation Method 9: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 500 mg of AgCl / SiO2-10% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 6.34 g of dimethyl sulfoxide, with a yield of 99%.

[0028] Implementation Method 10: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 500 mg of AgCl / SiO2-5% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction was complete, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 6.34 g of dimethyl sulfoxide, with a yield of 99%.

[0029] Implementation Method 11: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 500 mg of AgCl / SiO2-1% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction was completed, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 6.34 g of dimethyl sulfoxide, with a yield of 99%, as shown in Table 1 below.

[0030] Implementation Method 12: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 500 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 6.34 g of dimethyl sulfoxide, with a yield of 99% as shown in Table 1 below.

[0031] Implementation Method 13: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 500 mg of AgCl / Al3O2- 0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 6.08 g of dimethyl sulfoxide, with a yield of 95%.

[0032] Implementation Method 14: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 500 mg of AgCl / TiO₂-0.1% catalyst, were added to a reaction vessel. The mixture was stirred at 25°C for 5 h. After the reaction, the silver chloride catalyst was separated by filtration. The solution was extracted with ethyl acetate, and the organic phases were combined. The solvent was evaporated under reduced pressure to obtain 5.76 g of dimethyl sulfoxide, with a yield of 90%.

[0033] Example 15: 6.2 g (100 mmol) of dimethyl sulfide and 12.1 g (110 mmol) of hydrogen peroxide (30%), along with 500 mg of AgBr / TiO2-0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction, the silver bromide catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 5.76 g of dimethyl sulfoxide, with a yield of 90%.

[0034] Implementation Method 16: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 500 mg of AgI / TiO2-0.1% catalyst, were added to a reaction vessel. The mixture was stirred at 25°C for 5 h. After the reaction, the silver iodide catalyst was separated by filtration. The solution was extracted with ethyl acetate, and the organic phases were combined. The solvent was evaporated under reduced pressure to obtain 5.64 g of dimethyl sulfoxide, with a yield of 88%.

[0035] In Example 17, 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 200 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction was completed, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 6.28 g of dimethyl sulfoxide, with a yield of 98%, as shown in Table 1 below.

[0036] Implementation Method 18: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 150 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction was completed, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 5.9 g of dimethyl sulfoxide, with a yield of 92%, as shown in Table 1 below.

[0037] Implementation Method 19: 6.2 g (100 mmol) of dimethyl sulfide and 1.1 g (100 mmol) of hydrogen peroxide (30%), along with 100 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction was completed, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 6.27 g of dimethyl sulfoxide, with a yield of 98%, as shown in Table 1 below.

[0038] Table 1: Reaction status of AgCl / SiO2 at different addition amounts and reaction times

[0039]

[0040]

[0041] (TOF indicates the amount of sulfide converted by a single silver catalyst per unit time)

[0042] Example 20: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 100 mg of AgBr / TiO2-0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 5.63 g of dimethyl sulfoxide, with a yield of 88%.

[0043] Example 21: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 100 mg of AgI / TiO2- 0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction, the silver iodide catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 5.12 g of dimethyl sulfoxide, with a yield of 80%.

[0044] Implementation Method 22: 6.2 g (100 mmol) of dimethyl sulfide and 12.1 g (110 mmol) of hydrogen peroxide (30%) were added to a reaction vessel, along with 100 mg of AgCl / SiO2- 0.1% catalyst. The mixture was stirred at 25°C for 5 h. After the reaction, the silver chloride catalyst was separated by filtration. The solution was extracted with ethyl acetate, and the organic phases were combined. The solvent was evaporated under reduced pressure to obtain 6.34 g of dimethyl sulfoxide, with a yield of 99%.

[0045] Implementation Method 23: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 100 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 5 h. After the reaction, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 5.95 g of dimethyl sulfoxide, with a yield of 93%.

[0046] Implementation Method 24: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 100 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel and stirred at 20°C for 5 h. After the reaction, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 5.76 g of dimethyl sulfoxide, with a yield of 90%.

[0047] Example 25: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 100 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel and stirred at 35°C for 5 h. After the reaction, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 6.08 g of dimethyl sulfoxide, with a yield of 95%.

[0048] Implementation Method 26: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 100 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 3 h. After the reaction, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 5.44 g of dimethyl sulfoxide, with a yield of 85%.

[0049] Implementation Method 27: 6.2 g (100 mmol) of dimethyl sulfide and 12.1 g (110 mmol) of hydrogen peroxide (30%), along with 100 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel. The mixture was stirred at 25°C for 3 h. After the reaction, the silver chloride catalyst was separated by filtration. The solution was extracted with ethyl acetate, and the organic phases were combined. The solvent was evaporated under reduced pressure to obtain 5.632 g of dimethyl sulfoxide, with a yield of 88%.

[0050] Implementation Method 28: 6.2 g (100 mmol) of dimethyl sulfide and 11 g (100 mmol) of hydrogen peroxide (30%), along with 100 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel and stirred at 25°C for 20 h. After the reaction, the silver chloride catalyst was separated by filtration, the solution was extracted with ethyl acetate, the organic phases were combined, and the solvent was evaporated under reduced pressure to obtain 6.34 g of dimethyl sulfoxide, with a yield of 99%.

[0051] Implementation Method 29: 6.2 g (100 mmol) of dimethyl sulfide and 12.1 g (110 mmol) of hydrogen peroxide (30%), along with 100 mg of AgCl / SiO2-0.1% catalyst, were added to a reaction vessel. The mixture was stirred at 25°C for 20 h. After the reaction, the silver chloride catalyst was separated by filtration. The solution was extracted with ethyl acetate, and the organic phases were combined. The solvent was evaporated under reduced pressure to obtain 6.34 g of dimethyl sulfoxide, with a yield of 99%.

[0052]

[0053] Example 30: Preparation of methyl phenyl sulfoxide as shown in Formula 2. 6.2 g (50 mmol) of methyl phenyl sulfide, 5.5 g (50 mmol) of hydrogen peroxide (30%), and 500 mg of the catalyst prepared in Example 4 were added to a reaction vessel. The mixture was stirred at 45 degrees Celsius for 5 h. After the reaction was complete, the mixture was extracted with ethyl acetate, the silver chloride catalyst was separated by filtration, and the solvent was evaporated under reduced pressure to obtain 7.23 g of methyl phenyl sulfoxide, with a yield of 95%.

[0054] Example 31: Preparation of methyl phenyl sulfoxide as shown in Formula 2. 6.2 g (50 mmol) of methyl phenyl sulfide, 5.5 g (50 mmol) of hydrogen peroxide (30%), and 100 mg of the catalyst prepared in Example 4 were added to a reaction vessel. The mixture was stirred at 45 degrees Celsius for 5 h. After the reaction was complete, the mixture was extracted with ethyl acetate, the silver chloride catalyst was separated by filtration, and the solvent was evaporated under reduced pressure to obtain 7.46 g of methyl phenyl sulfoxide, with a yield of 98%.

[0055] Example 32: Preparation of methyl phenyl sulfoxide as shown in Formula 2. 6.2 g (50 mmol) of methyl phenyl sulfide, 6.6 g (60 mmol) of hydrogen peroxide (30%), and 100 mg of the catalyst prepared in Example 4 were added to a reaction vessel. The mixture was stirred at 45 degrees Celsius for 5 h. After the reaction was complete, the mixture was extracted with ethyl acetate, the silver chloride catalyst was separated by filtration, and the solvent was evaporated under reduced pressure to obtain 7.566 g of methyl phenyl sulfoxide, with a yield of 99%.

[0056] The catalyst washed and dried after reaction in Implementation Method 19 was reused. The process flow is consistent with the implementation case, and the catalyst recovery and utilization status is shown in Table 2 below:

[0057] Table 2:

[0058] Number of recyclings Dimethyl sulfoxide yield 1 98％ 2 98％ 3 97％ 4 98％ 5 97％

[0059] The catalyst washed and dried after the reaction in Implementation Method 31 was reused. The process flow is consistent with the implementation case, and the catalyst recovery and utilization status is shown in Table 3 below:

[0060] Table 3:

[0061] Number of recyclings Methylphenyl sulfoxide yield 1 98％ 2 96％ 3 94％ 4 93％ 5 94％

[0062] The experimental results of catalyst reuse in Tables 2 and 3 show that the silver catalyst has good reusability.

Claims

1. A method for preparing sulfoxide by silver catalytic oxidation, comprising the following steps: a) preparation of silver catalyst: silver nitrate and carrier are put into a container, stirred for 2-3 hours, then potassium halide is added, and stirred for 1-2 hours, and then dried to obtain silver catalyst; the silver halide in the prepared silver catalyst accounts for 0.1%-10% of the total mass of the catalyst; the carrier is silicon oxide, aluminum oxide or titanium oxide; b) preparation of sulfoxide: thioether is put into a container, hydrogen peroxide and the silver catalyst prepared in step a) are added, the reaction temperature is controlled at 25-45℃, the reaction time is 3-20 hours, and sulfoxide is generated by silver catalysis; the thioether is dimethyl sulfide or methyl phenyl sulfide; the sulfoxide is dimethyl sulfoxide or methyl phenyl sulfoxide.

2. The method of claim 1, wherein In step a, the mass ratio of silver nitrate to carrier is 1:(6.7-850); the mass ratio of silver nitrate to potassium halide is 1:(0.4-0.7).

3. The method of claim 1, wherein In step a, the potassium halide is potassium chloride, potassium bromide or potassium iodide.

4. The method of claim 1, wherein In step b, the added mass of silver catalyst is 1.6%-8.5% of the mass of thioether.

5. The method of claim 1, wherein In step b, the molar ratio of hydrogen peroxide to thioether is 1:(1.0-1.1).

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