Electrochemical preparation method of dimethyl sulfoxide

Abstract

The invention relates to the technical field of electrochemical synthesis, in particular to an electrochemical preparation method of dimethyl sulfoxide, which comprises the following steps: uniformly mixing a solvent, dimethyl sulfide, water and electrolyte to obtain an electrolysis system, and carrying out electrolytic reaction on the obtained electrolysis system to obtain dimethyl sulfoxide. According to the electrochemical preparation method of the dimethyl sulfoxide, the dimethyl sulfide is taken as a raw material, and the dimethyl sulfoxide is obtained in one step with high Faraday efficiency. Compared with a traditional dimethyl sulfoxide synthesis method, the method has the advantages of small pollution, high atom utilization rate and weak corrosion to devices, and meets the requirements of green and safe production. According to the electrochemical preparation method of the dimethyl sulfoxide, an additional oxidant is not needed, and the only by-product is hydrogen, so that the requirement of green synthesis is met. And moreover, the Faraday efficiency of the reaction is high, and the method has a better industrial application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical synthesis, and in particular to an electrochemical preparation method of dimethyl sulfoxide. Background Art

[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 has the characteristics of high polarity, high boiling point, high water solubility, and aproticity. It can dissolve most organic matter and is one of the commonly used organic solvents. It is widely used in many industrial fields.

[0003] In the pharmaceutical industry, dimethyl sulfoxide itself can have anti-inflammatory, analgesic, diuretic, sedative and other effects. It can also be directly used as a raw material and carrier for certain drugs, and is also used as an extractant by many chemical and pharmaceutical companies. In the polymer industry, dimethyl sulfoxide also has a high selective extraction ability. It is used as a polymerization and condensation solvent for acrylic resin and polysulfone resin, a polymerization spinning solvent for polyacrylonitrile and acetate fiber, an extraction solvent for the separation of alkanes and aromatics, and a reaction medium for the extraction of aromatics and butadiene, acrylic spinning, plastic solvents and organic synthetic dyes. Dimethyl sulfoxide is also used in the polymerization and spinning process of acrylonitrile, and is used as a solvent in the synthesis and manufacture of carbon fibers. In the pesticide industry, dimethyl sulfoxide as a reaction solvent can significantly improve the conversion rate and yield in the pesticide production process, and can be used as a reaction solvent in the production process of various pesticides. In the field of electronic communications, dimethyl sulfoxide is mainly used as a cleaning agent and stripping agent for electronic components, and is irreplaceable in some fields. With the revolutionary changes in 5G communications, big data, Internet of Things, automotive electronics, industrial automation, and other fields, the market demand for dimethyl sulfoxide will be further stimulated.

[0004] The traditional synthesis of dimethyl sulfoxide uses dimethyl sulfide as a substrate and high-priced nitrogen oxides or hydrogen peroxide as an oxidant. The former is somewhat polluting, while the latter is costly and requires selectivity control. The use of dimethyl sulfoxide green electrosynthesis coupled hydrogen production technology can directly oxidize the substrate with electricity in an aqueous solution without the addition of an oxidant, while achieving efficient conversion at the anode and releasing hydrogen at the cathode.

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

[0006] The object of the present invention is to provide an electrochemical preparation method of dimethyl sulfoxide, which realizes the conversion of dimethyl sulfide to dimethyl sulfoxide in one step, and the steps are simple and environmentally friendly.

[0007] The scheme adopted by the present invention to achieve the purpose is: an electrochemical preparation method of dimethyl sulfoxide, comprising the following steps:

[0008] The solvent, dimethyl sulfide, water, additives and electrolyte are uniformly mixed to obtain an electrolytic system, and the obtained electrolytic system is subjected to an electrolytic reaction to obtain 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, an additive is further included, and the additive includes at least one of sulfuric acid, acetic acid, hydrogen chloride, hydrogen bromide, hydrogen iodide and trifluoroacetic acid, and the concentration of the additive in the electrolysis system is 0-0.5 mol / L.

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

[0012] Preferably, the solvent is at least one of 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 may be water alone or an organic solvent alone. A preferred embodiment is that the solvent is a mixture of water and an organic solvent.

[0014] When the solvent is water or a mixture of water and an 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 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 electrolysis system is 0.1M-3.0M.

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

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

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

[0019] Preferably, the method further comprises: after the reaction is completed, distilling the electrolyte and collecting it through low temperature condensation to obtain a dimethyl sulfoxide product.

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

[0021] The electrochemical preparation method of dimethyl sulfoxide of the present invention uses dimethyl sulfide as a raw material and obtains dimethyl sulfoxide in one step with high Faraday efficiency. Compared with the traditional synthesis method of dimethyl sulfoxide, the method has less pollution, high atomic utilization rate, weak corrosion to the device, and meets the requirements of green and safe production.

[0022] The electrochemical preparation method of dimethyl sulfoxide of the present invention does not require the use of an additional oxidant, and the only byproduct is hydrogen, which meets the requirements of green synthesis. In addition, the reaction has a high Faraday efficiency and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] The following will be combined with specific implementation methods and examples to specifically describe the embodiments of the present invention, and the advantages and various effects of the embodiments of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementation methods and examples are used to illustrate the embodiments of the present invention, rather than to limit the embodiments of the present invention.

[0025] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood according to the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the embodiments of the present invention belong. In the event of a conflict, this specification takes precedence.

[0026] Unless otherwise specified, various 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 solution provided by the embodiment of the present invention is to solve the above technical problems, and the overall idea is as follows:

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

[0029] The solvent, dimethyl sulfide, water and electrolyte are mixed to obtain an electrolysis system, and an electrolysis 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 electrolysis system is 0.1-2.0 mol / L, and the molar ratio of water to dimethyl sulfide is 1-100:1.

[0034] The invention also includes additives, which include at least one of sulfuric acid, acetic acid, hydrogen chloride, hydrogen bromide, hydrogen iodide and trifluoroacetic acid. The additives are helpful in inhibiting side reactions. The concentration of the additives in the electrolysis system is 0-0.5 mol / L.

[0035]

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

[0037] The molar ratio within the range is conducive to the complete reaction. If the molar ratio is not within the range of the present invention, the reaction efficiency will be low and the reaction voltage will be too high.

[0038] The solvent is at least one of 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 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. Such electrolytes can all play a role in transferring electrons.

[0040] The molar concentration of the electrolyte in the electrolysis system is in the range of 0.1M-3.0M.

[0041] In the electrolytic reaction, an integrated electrolytic cell equipped with a stirrer and electrodes is used.

[0042] In the electrolytic reaction, the anode used includes 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 one of platinum sheet, stainless steel, iron sheet, and nickel sheet.

[0043] The current density of the electrolysis reaction is 10-650 mA / cm 2 This current is conducive to the efficient conversion of dimethyl sulfide. If the current is too high, the system will release heat seriously and the reaction selectivity will decrease.

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

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

[0046] In summary, the present invention uses dimethyl sulfide as a raw material and obtains dimethyl sulfoxide in one step with high Faraday efficiency. Compared with the traditional synthesis method of dimethyl sulfoxide, this method has low pollution, high atomic utilization, weak corrosion to the device, and meets the requirements of green and safe production. The method does not require the use of additional oxidants, and the only by-product is hydrogen, which meets the requirements of green synthesis. And the Faraday efficiency of the reaction is high, and it has good prospects for industrial application. The following will be combined with the embodiments and comparative experimental data to describe in detail a method for preparing dimethyl sulfoxide by electrochemical method of the present application.

[0047] Example 1

[0048]

[0049] At room temperature, dimethyl sulfide (1,4 mmol), NaBr (1.5 mmol), concentrated sulfuric acid (2 mmol), acetonitrile (5 mL) and water (5 mL) were added to the reaction tube under air atmosphere; carbon cloth was used as anode and stainless steel sheet was used as cathode. The electrode area was 1 cm 2 8 mF of electricity was passed through the mixture at a constant current of 450 mA. After the reaction was completed and purified by distillation, the Faraday efficiency of the product was 57%.

[0050] Example 2

[0051] In this example, acetonitrile is changed to dimethyl sulfoxide, and other conditions are the same as those in Example 1. The Faradaic efficiency of the product is 49%.

[0052] Example 3

[0053] In this example, acetonitrile is changed to tetrahydrofuran, and other conditions are the same as those in Example 1. The Faraday efficiency of the product is 55%.

[0054] Example 4

[0055] In this example, acetonitrile is changed to N,N-dimethylformamide, and other conditions are the same as those in Example 1. The Faraday efficiency of the product is 62%.

[0056] Example 5

[0057]

[0058] At room temperature, 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 the reaction tube under air atmosphere; carbon cloth was used as anode, stainless steel sheet was used as cathode, and the electrode area was 1 cm 2 The mixture was charged with 8 mF of electricity at a constant current of 450 mA. After the reaction was completed and purified by distillation, the Faraday efficiency of the product was 65%.

[0059] Example 6

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

[0061] Example 7

[0062]

[0063] At room temperature, 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 in an air atmosphere; carbon cloth was used as the anode and nickel sheet was used as the cathode. The electrode area was 1 cm 2 8 mF of electricity was passed through the mixture at a constant current of 450 mA. After the reaction was completed and purified by distillation, the Faraday efficiency of the product was 60%.

[0064] Example 8

[0065] In this embodiment, the cathode is changed to stainless steel, and other conditions are the same as those in Embodiment 7. The product Faraday efficiency is 65%.

[0066] Example 9

[0067]

[0068] At room temperature, dimethyl sulfide (1,4 mmol), KBr (1.5 mmol), concentrated sulfuric acid (2 mmol), DMAc (5 mL) and water (5 mL) were added to the reaction tube under air atmosphere; carbon cloth was used as anode and stainless steel sheet was used as cathode. The electrode area was 1 cm 2 8 mF of electricity was passed through the mixture at a constant current of 450 mA. After the reaction was completed and purified by distillation, the Faraday efficiency of the product was 70%.

[0069] Example 10

[0070] In this example, the electrolyte was changed to NaCl, and other conditions were the same as those in Example 9. The product Faraday efficiency was 74%.

[0071] Embodiment 11

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

[0073] Example 12

[0074] In this example, the electrolyte is changed to TEACl (tetraethylammonium chloride), and other conditions are the same as those in Example 9. The product Faraday efficiency is 80%.

[0075] Example 13

[0076] In this example, the electrolyte is changed to TBACl (tetrabutylammonium chloride), and other conditions are the same as those in Example 9. The product Faraday efficiency is 84%.

[0077] Embodiment 14

[0078]

[0079] At room temperature, dimethyl sulfide (1,4 mmol), TBACl (1.5 mmol), acetic acid (2 mmol), DMAc (5 mL) and water (5 mL) were added to the reaction tube under air atmosphere; carbon cloth was used as anode and stainless steel sheet was used as cathode. The electrode area was 1 cm 2 8 mF of electricity was passed through the mixture at a constant current of 450 mA. After the reaction was completed and purified by distillation, the Faraday efficiency of the product was 78%.

[0080] Embodiment 15

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

[0082] Example 16

[0083]

[0084] At room temperature, dimethyl sulfide (1,4 mmol), TBACl (1.5 mmol), trifluoroacetic acid (2 mmol), DMAc (5 mL) and water (5 mL) were added to the reaction tube under air atmosphere; carbon cloth was used as anode and stainless steel sheet was used as cathode. The electrode area was 1 cm 2 8 mF of electricity was passed through the mixture at a constant current of 450 mA. After the reaction was completed and purified by distillation, the Faraday efficiency of the product was 78%.

[0085] Embodiment 17

[0086] In this embodiment, the current is changed to 650 mA, and the amount of electricity remains unchanged. Other conditions are the same as those in Example 16, and the product Faraday efficiency is 73%.

[0087] Embodiment 18

[0088] In this embodiment, the current is changed to 10 mA, and the amount of electricity remains unchanged. Other conditions are the same as those in Example 16, and the product Faraday efficiency is 80%.

[0089] Embodiment 19

[0090] In this embodiment, the current is changed to 150 mA, and the amount of electricity remains unchanged. Other conditions are the same as those in Example 16, and the product Faraday efficiency is 79%.

[0091] Embodiment 20

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

[0093] Embodiment 21

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

[0095] Embodiment 22

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

[0097] Embodiment 23

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

[0099] Embodiment 24

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

[0101] Embodiment 25

[0102] In this example, no sulfuric acid, acetic acid, hydrogen chloride, hydrogen bromide, hydrogen iodide or trifluoroacetic acid was added, and 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 changed to tetrabutylammonium tetrafluoroborate. The other steps were the same as those in Example 16, and the Faraday efficiency of the product was only 25%.

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

[0106] Table 1

[0107] Group Faraday efficiency 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％ Embodiment 11 77％ Example 12 80％ Example 13 84％ Embodiment 14 78％ Embodiment 15 86％ Example 16 78％ Embodiment 17 73％ Embodiment 18 80％ Embodiment 19 79％ Embodiment 20 81％ Embodiment 21 82％ Embodiment 22 60％ Embodiment 23 45％ Embodiment 24 67％ Embodiment 25 71％ Comparative Example 1 25％

[0108] From the data in Table 1, we can see that:

[0109] In Examples 1-25 of the present invention, the Faraday efficiency of the dimethyl sulfoxide product is better than that of Comparative Example 1. This indicates that the product dimethyl sulfoxide can be synthesized only when the reaction conditions are within the scope of the present invention.

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

[0111] The above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and changes can be made without departing from the principle of the present invention, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims

1. An electrochemical preparation method of dimethyl sulfoxide, characterized in that: The following steps are involved: The solvent, dimethyl sulfide, water and electrolyte are mixed to obtain an electrolytic system, and the obtained electrolytic system is subjected to an electrolytic reaction to obtain dimethyl sulfoxide.

2. The electrochemical preparation method of dimethyl sulfoxide according to claim 1, characterized in that: 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.

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

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

5. The electrochemical preparation method of dimethyl sulfoxide according to claim 1, characterized in that: The solvent is at least one of water, methanol, ethanol, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetone, ethyl acetate, tetrahydrofuran and 1,4-dioxane.

6. The electrochemical preparation method of dimethyl sulfoxide according to claim 1, characterized in that: 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 electrolysis system is 0.1M-3.0M.

7. The electrochemical preparation method of dimethyl sulfoxide according to claim 1, characterized in that: 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.

8. The electrochemical preparation method of dimethyl sulfoxide according to claim 1, characterized in that: The electrolysis reaction is a constant current electrolysis reaction with a current density of 10-650 mA / cm 2 .

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

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

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