An electrochemical method for the preparation of dimethyl sulfoxide

Abstract

The present application relates to the technical field of electrochemical synthesis, and particularly relates to an electrochemical preparation method of dimethyl sulfoxide, comprising the following steps: mixing a solvent, dimethyl sulfide, water and an electrolyte to obtain an electrolyte system, and performing electrolysis reaction on the obtained electrolyte system to obtain dimethyl sulfoxide. The electrochemical preparation method of dimethyl sulfoxide has high Faraday efficiency, and dimethyl sulfoxide is obtained in one step by taking dimethyl sulfide as a raw material. Compared with a traditional synthesis method of dimethyl sulfoxide, the method has small pollution, high atom utilization rate, weak corrosion to a device, and meets the requirements of green and safe production. The electrochemical preparation method of dimethyl sulfoxide does not need to use an additional oxidant, and the only by-product is hydrogen, which meets the requirements of green synthesis. Moreover, the reaction has high Faraday efficiency, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the technical field of electrochemical synthesis, and specifically to an electrochemical preparation method of dimethyl sulfoxide. Background Technology

[0002] Dimethyl sulfoxide (DMSO) is a commonly used sulfur-containing organic compound. It is a colorless and odorless liquid at room temperature with extremely low toxicity. It is characterized by high polarity, high boiling point, high water solubility, and aproticity. It can dissolve most organic compounds and is one of the commonly used organic solvents, widely used in many industrial fields.

[0003] In the pharmaceutical industry, dimethyl sulfoxide (DMSO) itself has anti-inflammatory, analgesic, diuretic, and sedative effects. It can also be used directly as a raw material and carrier for certain drugs and is widely used as an extractant by chemical and pharmaceutical companies. In the polymer industry, DMSO has high selective extraction capabilities and is used as a polymerization and condensation solvent for acrylic resins and polysulfone resins, a spinning solvent for the polymerization of polyacrylonitrile and cellulose acetate, an extraction solvent for the separation of alkanes and aromatics, and for the extraction of aromatics and butadiene. It is also used as a solvent in acrylonitrile polymerization and spinning processes, and as a solvent in the synthesis of carbon fibers. In the pesticide industry, DMSO, as a reaction solvent, can significantly improve the conversion rate and yield in pesticide production and can be used as a reaction solvent in various pesticide production processes. In the electronics and communications field, DMSO is mainly used as a cleaning agent and stripping agent for electronic components, and it is irreplaceable in some areas. Revolutionary changes in fields such as 5G communication, big data, the Internet of Things, automotive electronics, and industrial automation will further stimulate market demand for dimethyl sulfoxide.

[0004] Traditional synthesis of dimethyl sulfoxide uses dimethyl sulfide as a substrate and high-valence nitrogen oxides or hydrogen peroxide as oxidants. The former causes some pollution, while the latter is costly and requires selective control. Using dimethyl sulfoxide green electrosynthesis coupled with hydrogen production technology, the substrate can be directly oxidized in aqueous solution without the addition of an oxidant. This achieves efficient anodic conversion while hydrogen is evolved at the cathode.

[0005] Therefore, it is necessary to develop an electrochemical preparation method for dimethyl sulfoxide to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide an electrochemical preparation method for dimethyl sulfoxide, which achieves the conversion of dimethyl sulfide to dimethyl sulfoxide in one step. The method is simple and environmentally friendly.

[0007] The solution adopted by this invention to achieve its objective is: an electrochemical preparation method for dimethyl sulfoxide, comprising the following steps:

[0008] An electrolytic system is obtained by mixing solvent, dimethyl sulfide, water, additives and electrolyte. The resulting electrolytic system is then subjected to an electrolytic reaction to produce dimethyl sulfoxide.

[0009] Preferably, the concentration of dimethyl sulfide in the electrolysis system is 0.1-2.0 mol / L, and the molar ratio of water to dimethyl sulfide is 1-100:1.

[0010] Preferably, the system further includes additives, which include at least one of sulfuric acid, acetic acid, hydrogen chloride, hydrogen bromide, hydrogen iodide, and trifluoroacetic acid, and the concentration of the additives in the electrolysis system is 0-0.5 mol / L.

[0011] Preferably, the molar ratio of the dimethyl sulfide to the additive is 0.1-10:0-1.

[0012] Preferably, the solvent is at least one selected from water, methanol, ethanol, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetone, ethyl acetate, tetrahydrofuran, and 1,4-dioxane.

[0013] The solvent can be water or an organic solvent, with the preferred option being a mixture of water and an organic solvent.

[0014] When the solvent is water or a mixture of water and organic solvent, the water in the system of the present invention has two uses: one part is used as a reactant to react with dimethyl sulfide, and the other part is used as a solvent.

[0015] Preferably, the electrolyte comprises at least one of sodium iodide, potassium iodide, lithium iodide, ammonium iodide, tetraethylammonium iodide, tetrabutylammonium iodide, sodium bromide, potassium bromide, lithium bromide, ammonium bromide, tetraethylammonium bromide, tetrabutylammonium bromide, sodium chloride, potassium chloride, lithium chloride, ammonium chloride, tetraethylammonium chloride, and tetrabutylammonium chloride, and the concentration of the electrolyte in the electrolysis system is 0.1M-3.0M.

[0016] Preferably, in the electrolytic reaction, the anode used includes any one of carbon sheet, graphite felt, carbon cloth, carbon paper, and titanium-based electrode loaded with ruthenium oxide or iridium oxide; the cathode used is any one of platinum sheet, stainless steel, iron sheet, and nickel sheet.

[0017] Preferably, the electrolysis reaction is a constant current electrolysis reaction with a current density of 10-650 mA / cm². 2 .

[0018] Preferably, the temperature of the electrolysis reaction is 0-40°C.

[0019] Preferably, the method further includes: after the reaction is completed, distilling the electrolyte and collecting the dimethyl sulfoxide product by low-temperature condensation.

[0020] The present invention has the following advantages and beneficial effects:

[0021] The electrochemical preparation method of dimethyl sulfoxide of the present invention obtains dimethyl sulfoxide in one step using dimethyl sulfide as a raw material with high Faradaic efficiency. Compared with the traditional synthesis method of dimethyl sulfoxide, this method has less pollution, higher atom utilization, and less corrosiveness to equipment, meeting the requirements of green and safe production.

[0022] The electrochemical preparation method of dimethyl sulfoxide of this invention does not require the use of an additional oxidant, and the only byproduct is hydrogen gas, which meets the requirements of green synthesis. Furthermore, the reaction has high Faraday efficiency and shows good prospects for industrial application. Attached Figure Description

[0023] Figure 1 This is the chemical reaction equation in the electrochemical preparation method of dimethyl sulfoxide of the present invention. Detailed Implementation

[0024] The following detailed description of the embodiments and examples will illustrate the present invention in more detail, thereby making the advantages and various effects of the embodiments more clearly apparent. Those skilled in the art should understand that these detailed embodiments and examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0025] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention pertain. In the event of any conflict, this specification shall prevail.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0027] The technical solutions provided by the embodiments of the present invention are for solving the above-mentioned technical problems, and the overall approach is as follows:

[0028] According to a typical embodiment of the present invention, an electrochemical preparation method for dimethyl sulfoxide is provided, the method comprising:

[0029] An electrolytic system is obtained by mixing a solvent, dimethyl sulfide, water, and electrolyte. The electrolytic reaction is carried out in a constant current mode to obtain dimethyl sulfoxide.

[0030] The chemical equation for this reaction is:

[0031]

[0032] In the above technical solution,

[0033] The concentration of dimethyl sulfide in the electrolytic system is 0.1-2.0 mol / L, and the molar ratio of water to dimethyl sulfide is 1-100:1.

[0034] It also includes additives, which include at least one of sulfuric acid, acetic acid, hydrogen chloride, hydrogen bromide, hydrogen iodide and trifluoroacetic acid. The use of such additives helps to suppress side reactions. The concentration of the additives in the electrolysis system is 0-0.5 mol / L.

[0035]

[0036] The molar ratio of the dimethyl sulfide to the additive is 0.1-10:0-1.

[0037] Within this molar ratio range, the reaction is more likely to complete completely. If the molar ratio is outside the range of this invention, it will lead to low reaction efficiency and excessively high reaction voltage.

[0038] The solvent is at least one selected from water, methanol, ethanol, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetone, ethyl acetate, tetrahydrofuran, and 1,4-dioxane.

[0039] The electrolyte includes one or more of the following: sodium iodide, potassium iodide, lithium iodide, ammonium iodide, tetraethylammonium iodide, tetrabutylammonium iodide, sodium bromide, potassium bromide, lithium bromide, ammonium bromide, tetraethylammonium bromide, tetrabutylammonium bromide, sodium chloride, potassium chloride, lithium chloride, ammonium chloride, tetraethylammonium chloride, and tetrabutylammonium chloride. These electrolytes can all function as electron transfer electrolytes.

[0040] The molar concentration of the electrolyte in the electrolysis system ranges from 0.1M to 3.0M.

[0041] The electrolysis reaction is carried out using an integrated electrolytic cell equipped with a stir bar and electrodes.

[0042] In the electrolytic reaction, the anode used includes one of the following: carbon sheet, graphite felt, carbon cloth, carbon paper, and titanium-based electrode loaded with ruthenium oxide or iridium oxide; the cathode used is one of the following: platinum sheet, stainless steel, iron sheet, and nickel sheet.

[0043] The current density of the electrolysis reaction is 10-650 mA / cm². 2 This current is favorable for the efficient conversion of dimethyl sulfide; however, if the current is too high, the system will become highly exothermic, and the reaction selectivity will decrease.

[0044] The temperature of the electrolysis reaction is 0-40℃.

[0045] The method further includes: after the reaction is completed, distilling the electrolyte and collecting the product dimethyl sulfoxide by low-temperature condensation.

[0046] In summary, this invention provides a one-step synthesis of dimethyl sulfoxide using dimethyl sulfide as a raw material with high Faradaic efficiency. Compared to traditional dimethyl sulfoxide synthesis methods, this method exhibits less pollution, higher atom utilization, and lower corrosiveness to equipment, meeting the requirements of green and safe production. This method does not require additional oxidants, and the only byproduct is hydrogen gas, fulfilling the requirements of green synthesis. Furthermore, the high Faradaic efficiency of the reaction indicates promising prospects for industrial application. The following detailed description of the electrochemical preparation method of dimethyl sulfoxide according to this application, combined with examples and comparative experimental data, will further illustrate this method.

[0047] Example 1

[0048]

[0049] At room temperature and under an air atmosphere, dimethyl sulfide (1.4 mmol), NaBr (1.5 mmol), concentrated sulfuric acid (2 mmol), acetonitrile (5 mL), and water (5 mL) were added to a reaction tube; carbon cloth was used as the anode, and a stainless steel sheet was used as the cathode, with an electrode area of ​​1 cm². 2 The mixture was subjected to a constant current of 450 mA and a charge of 8 mF. After the reaction was completed and purified by distillation, the product had a Faraday efficiency of 57%.

[0050] Example 2

[0051] In this embodiment, acetonitrile was replaced with dimethyl sulfoxide, and all other conditions were the same as in Example 1. The product had a Faraday efficiency of 49%.

[0052] Example 3

[0053] In this embodiment, acetonitrile was replaced with tetrahydrofuran, and all other conditions were the same as in Example 1. The product Faraday efficiency was 55%.

[0054] Example 4

[0055] In this example, acetonitrile was replaced with N,N-dimethylformamide, and all other conditions were the same as in Example 1. The product had a Faraday efficiency of 62%.

[0056] Example 5

[0057]

[0058] At room temperature and under an air atmosphere, dimethyl sulfide (1.4 mmol), NaBr (1.5 mmol), concentrated sulfuric acid (2 mmol), DMAc (N,N-dimethylacetamide) (5 mL), and water (5 mL) were added to a reaction tube; carbon cloth was used as the anode, and a stainless steel sheet was used as the cathode, with an electrode area of ​​1 cm². 2 The mixture was subjected to a constant current of 450 mA and a charge of 8 mF. After the reaction was completed, the product was purified by distillation, and the Faraday efficiency was 65%.

[0059] Example 6

[0060] In this embodiment, the anode is changed to graphite felt, and all other conditions are the same as in Example 5. The product Faraday efficiency is 63%.

[0061] Example 7

[0062]

[0063] At room temperature and under an air atmosphere, dimethyl sulfide (1.4 mmol), NaBr (1.5 mmol), concentrated sulfuric acid (2 mmol), DMAc (5 mL), and water (5 mL) were added to a reaction tube; carbon cloth was used as the anode, and a nickel sheet was used as the cathode, with an electrode area of ​​1 cm². 2 The mixture was subjected to a constant current of 450 mA and a charge of 8 mF. After the reaction was completed and purified by distillation, the product had a Faraday efficiency of 60%.

[0064] Example 8

[0065] In this embodiment, the cathode is replaced with stainless steel, and all other conditions are the same as in Example 7. The product Faraday efficiency is 65%.

[0066] Example 9

[0067]

[0068] At room temperature and under an air atmosphere, dimethyl sulfide (1.4 mmol), KBr (1.5 mmol), concentrated sulfuric acid (2 mmol), DMAc (5 mL), and water (5 mL) were added to a reaction tube; carbon cloth was used as the anode, and a stainless steel sheet was used as the cathode, with an electrode area of ​​1 cm². 2 The mixture was subjected to a constant current of 450 mA and a charge of 8 mF. After the reaction was completed and purified by distillation, the product had a Faraday efficiency of 70%.

[0069] Example 10

[0070] In this embodiment, the electrolyte is changed to NaCl, and all other conditions are the same as in Example 9. The product Faraday efficiency is 74%.

[0071] Example 11

[0072] In this embodiment, the electrolyte was changed to KCl, and all other conditions were the same as in Example 9. The product Faraday efficiency was 77%.

[0073] Example 12

[0074] In this embodiment, the electrolyte was changed to TEACl (tetraethylammonium chloride), and all other conditions were the same as in Example 9. The product Faraday efficiency was 80%.

[0075] Example 13

[0076] In this embodiment, the electrolyte was changed to TBACl (tetrabutylammonium chloride), and all other conditions were the same as in Example 9. The product Faraday efficiency was 84%.

[0077] Example 14

[0078]

[0079] At room temperature and under an air atmosphere, dimethyl sulfide (1.4 mmol), TBACl (1.5 mmol), acetic acid (2 mmol), DMAc (5 mL), and water (5 mL) were added to a reaction tube; carbon cloth was used as the anode, and a stainless steel sheet was used as the cathode, with an electrode area of ​​1 cm². 2 The mixture was subjected to a constant current of 450 mA and a charge of 8 mF. After the reaction was completed, the product was purified by distillation, and the Faraday efficiency was 78%.

[0080] Example 15

[0081] In this embodiment, the additive was changed to TFA (trifluoroacetic acid), and all other conditions were the same as in Example 14. The product had a Faraday efficiency of 86%.

[0082] Example 16

[0083]

[0084] At room temperature and under an air atmosphere, dimethyl sulfide (1.4 mmol), TBACl (1.5 mmol), trifluoroacetic acid (2 mmol), DMAc (5 mL), and water (5 mL) were added to a reaction tube; carbon cloth was used as the anode, and a stainless steel sheet was used as the cathode, with an electrode area of ​​1 cm². 2 The mixture was subjected to a constant current of 450 mA and a charge of 8 mF. After the reaction was completed, the product was purified by distillation, and the Faraday efficiency was 78%.

[0085] Example 17

[0086] In this embodiment, the current is changed to 650mA, while the charge remains the same. All other conditions are the same as in Example 16, and the product Faraday efficiency is 73%.

[0087] Example 18

[0088] In this embodiment, the current is changed to 10mA, while the charge remains the same. All other conditions are the same as in Example 16, and the product Faraday efficiency is 80%.

[0089] Example 19

[0090] In this embodiment, the current is changed to 150mA, while the charge remains the same. All other conditions are the same as in Example 16, and the product Faraday efficiency is 79%.

[0091] Example 20

[0092] In this embodiment, the reaction temperature was changed from room temperature to 0°C, and all other conditions were the same as in Example 16. The product Faraday efficiency was 81%.

[0093] Example 21

[0094] In this embodiment, the reaction temperature was changed from room temperature to 10°C, and all other conditions were the same as in Example 16. The product Faraday efficiency was 82%.

[0095] Example 22

[0096] In this embodiment, the reaction temperature was changed from room temperature to 40°C, and all other conditions were the same as in Example 16. The product Faraday efficiency was 60%.

[0097] Example 23

[0098] In this embodiment, no organic solvent was added. All other steps were the same as in Example 16, and the Faraday efficiency of the product was 45%.

[0099] Example 24

[0100] In this embodiment, the amount of water was reduced to twice the molar amount of dimethyl sulfide, and all other conditions were the same as in Example 16, with a product Faraday efficiency of 67%.

[0101] Example 25

[0102] In this embodiment, sulfuric acid, acetic acid, hydrogen chloride, hydrogen bromide, hydrogen iodide, or trifluoroacetic acid were not added, and all other conditions were the same as in Example 16. The product Faraday efficiency was 71%.

[0103] Comparative Example 1

[0104] In Comparative Example 1, the electrolyte was replaced with tetrabutylammonium tetrafluoroborate. All other steps were the same as in Example 16, and the product's Faraday efficiency was only 25%.

[0105] For ease of comparison, the experimental parameters of each embodiment and each comparative example are statistically analyzed as shown in Table 1.

[0106] Table 1

[0107] Example 1 57％ Example 2 49％ Example 3 55％ Example 4 62％ Example 5 65％ Example 6 63％ Example 7 60％ Example 8 65％ Example 9 70％ Example 10 74％ Example 11 77％ Example 12 80％ Example 13 84％ Example 14 78％ Example 15 86％ Example 16 78％ Example 17 73％ Example 18 80％ Example 19 79％ Example 20 81％ Example 21 82％ Example 22 60％ Example 23 45％ Example 24 67％ Example 25 71％ Comparative Example 1 25％

[0108] As can be seen from the data in Table 1:

[0109] In Examples 1-25 of this invention, the dimethyl sulfoxide product exhibited a better Faradaic efficiency than Comparative Example 1. This indicates that the product dimethyl sulfoxide can only be synthesized under reaction conditions within the scope of this invention.

[0110] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0111] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An electrochemical preparation method for dimethyl sulfoxide, characterized in that, Includes the following steps: An electrolytic system was obtained by mixing a solvent, dimethyl sulfide, water, and electrolyte. The resulting electrolytic system was then subjected to an electrolytic reaction to produce dimethyl sulfoxide. The concentration of dimethyl sulfide in the electrolytic system is 0.1-2.0 mol / L, and the molar ratio of water to dimethyl sulfide is 1-100:1; the electrolyte includes at least one of sodium iodide, potassium iodide, lithium iodide, ammonium iodide, tetraethylammonium iodide, tetrabutylammonium iodide, sodium bromide, potassium bromide, lithium bromide, ammonium bromide, tetraethylammonium bromide, tetrabutylammonium bromide, sodium chloride, potassium chloride, lithium chloride, ammonium chloride, tetraethylammonium chloride, and tetrabutylammonium chloride, and the concentration of the electrolyte in the electrolytic system is 0.1M-3.0M; In the electrolysis reaction, the anode used includes any one of carbon sheet, graphite felt, carbon cloth, carbon paper, and titanium-based electrode loaded with ruthenium oxide or iridium oxide; the cathode used is any one of platinum sheet, stainless steel, iron sheet, and nickel sheet; the electrolysis reaction is a constant current electrolysis reaction with a current density of 150-650 mA / cm². 2 ; The solvent is a mixture of water and at least one of methanol, ethanol, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetone, ethyl acetate, tetrahydrofuran, and 1,4-dioxane.

2. The electrochemical preparation method of dimethyl sulfoxide according to claim 1, characterized in that, It also includes additives, which include at least one of sulfuric acid, acetic acid, hydrogen chloride, hydrogen bromide, hydrogen iodide and trifluoroacetic acid, and the concentration of the additives in the electrolysis system is 0-0.5 mol / L.

3. The electrochemical preparation method of dimethyl sulfoxide according to claim 2, characterized in that, The molar ratio of the dimethyl sulfide to the additive is 0.1-10:0-1.

4. The electrochemical preparation method of dimethyl sulfoxide according to claim 1, characterized in that, The temperature of the electrolysis reaction is 0-40℃.

5. The electrochemical preparation method of dimethyl sulfoxide according to claim 1, characterized in that, The method further includes: after the reaction is completed, distilling the electrolyte and collecting it by low-temperature condensation to obtain the dimethyl sulfoxide product.

Images