Method for electrochemical synthesis of vulcanization accelerator NS

Abstract

The invention discloses a method for electrochemical synthesis of a vulcanization accelerator NS, and the method comprises the following steps: mixing 2-mercaptobenzothiazole, tert-butylamine, an electrolyte, a catalyst and methanol, carrying out an electrolytic reaction, and then carrying out post-treatment to obtain the vulcanization accelerator NS, the catalyst is alkyl substituted imidazole chloride ionic liquid. The simple, easily available and recyclable alkyl substituted imidazole chloride ionic liquid is used as the catalyst, the vulcanization accelerator NS can be efficiently electrochemically synthesized under the conditions of normal temperature, normal pressure and methanol solvent, and the method has the advantages of simple synthesis process, no toxicity, no pollution, high product yield and the like.

Description

Technical Field

[0001] This invention relates to the field of organic compound electrolytic preparation technology, specifically to a method for electrochemically synthesizing sulfidation accelerator NS, and more particularly to a green and low-cost method for synthesizing sulfidation accelerator NS. Technical Background N-tert-butyl-2-benzothiazole sulfenamide (NS), as a highly efficient post-curing accelerator in the rubber industry, plays a crucial role in improving the performance and production efficiency of rubber products. Its significant advantages lie in its ability to shorten curing time, optimize curing start-up characteristics, and impart excellent tensile strength, elasticity, abrasion resistance, and chemical stability to the vulcanizate. It is particularly suitable for applications in rubber products such as tire treads and conveyor belts, where high physical properties are required. Compared to traditional sulfenamide accelerators, NS does not generate nitrosamines, which pose a carcinogenic risk, during production and use. This environmentally friendly characteristic has led to its wider application in the increasingly stringent international environmental regulations. As the world's largest producer of rubber additives, China's annual demand for rubber accelerators has exceeded 400,000 tons, with high-performance sulfenamide accelerators occupying a significant market share. In summary, with its superior performance and environmental advantages, NS will undoubtedly play an increasingly important role in the rubber industry's transformation towards high-quality and sustainable development.

[0002] NS, as a highly efficient rubber vulcanization accelerator, is traditionally synthesized using 2-mercaptobenzothiazole as a raw material under the action of strong oxidants (such as NaClO or NaNO2) (Chem. Rev. 2014, 114, 2587.; Green Chem., 2017, 19, 2491). However, this method suffers from high energy consumption, the generation of high-salt wastewater, and nitrogen oxides. Electrocatalysis is a conversion process that uses electrical energy to drive chemical reactions, achieving material transformation under the combined action of an electric field and a catalyst (Angew. Chem., Int. Ed. 2022, 61, e202210123; Chem. Soc. Rev. 2021, 50, 7941.). Compared to traditional chemical oxidation methods, electrocatalysis directly uses electrical energy to drive the reaction, eliminating the need for additional oxidants and avoiding the generation of saline wastewater and harmful gases, thus offering greater advantages in terms of environmental friendliness. Electrocatalytic reactions typically proceed under mild conditions (room temperature and pressure), consuming relatively little energy and offering high controllability. They allow for precise regulation of electron transfer processes, enhancing reaction selectivity. Therefore, developing electrocatalytic synthesis of rubber additives holds significant research value and application potential. Lei Aiwen's team synthesized NS at room temperature and pressure using an electrocatalytic method, maintaining a good yield (CN202410438353.3). However, this method requires acetonitrile and methanol as a mixed solvent in conjunction with hydrogen chloride and tetraethylammonium bromide as catalysts to achieve a satisfactory yield. The use of hydrochloric acid and acetonitrile as catalysts and mixed solvents increases environmental pressure and reaction costs to some extent.

[0003] Based on the concept of green synthesis, it is essential to design a simple and green method for synthesizing NS under mild conditions in order to promote the development of green synthesis processes. Therefore, it is necessary to continue to improve the shortcomings of the current electrocatalytic synthesis methods for NS. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an electrochemical method for synthesizing the sulfidation accelerator NS. This method uses 2-mercaptobenzothiazole and tert-butylamine as raw materials, methanol as solvent, and alkyl-substituted imidazole chloride ionic liquid as catalyst. The construction of SN bonds is achieved through electrochemical methods, and the sulfidation accelerator NS is synthesized under mild conditions. The solvent used in this invention is more environmentally friendly and has a lower cost, and the catalyst used can be recycled, which is in line with the concept of green synthesis.

[0005] The specific technical solution of this invention is as follows: A method for electrochemically synthesizing a sulfidation accelerator NS, the method comprising: mixing 2-mercaptobenzothiazole (accelerator M), tert-butylamine, electrolyte, catalyst and methanol and then performing an electrolytic reaction, followed by post-treatment to obtain the sulfidation accelerator NS.

[0006] Furthermore, the catalyst is an alkyl-substituted imidazolium chloride ionic liquid. The alkyl-substituted imidazolium chloride ionic liquid includes one of 1-butyl-3-methylimidazolium chloride, 1-propyl-3-methylimidazolium chloride, and 1-ethyl-3-methylimidazolium chloride. This invention uses imidazolium chloride ionic liquid as a catalyst, which, compared with hydrochloric acid in the prior art, has unique advantages such as being environmentally friendly, recyclable, and non-corrosive to equipment.

[0007] Furthermore, the electrolyte is a quaternary ammonium salt, such as tetraethylammonium bromide, hexadecylammonium bromide, and tetrabutylammonium bromide.

[0008] Furthermore, the molar ratio of 2-mercaptobenzothiazole to tert-butylamine is 1:1.5-8, for example 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, preferably 1:3-8.

[0009] Furthermore, the molar ratio of 2-mercaptobenzothiazole to the catalyst is 1:0.05-0.5, for example 1:0.05, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, preferably 1:0.15-0.5.

[0010] Furthermore, the molar ratio of 2-mercaptobenzothiazole to the electrolyte is 1:0.25-1, for example 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:0.65, 1:0.7, 1:0.75, 1:0.8, 1:0.85, 1:0.9, 1:0.95, 1:1, preferably 1:0.5-1.

[0011] Furthermore, the molar ratio of 2-mercaptobenzothiazole to methanol is 1:80-125, for example 1:80, 1:85, 1:90, 1:95, 1:100, 1:105, 1:110, 1:115, 1:120, 1:125, preferably 1:90-115.

[0012] Furthermore, the electrode material used for electrolysis is a carbon plate or a graphite plate, preferably a graphite plate, which has the advantages of being inexpensive and corrosion-resistant.

[0013] Furthermore, the current density for electrolysis is 3–10 mA / cm². 2 For example, 3 mA / cm 2 4 mA / cm 2 5 mA / cm 26mA / cm 2 7 mA / cm 2 8 mA / cm 2 9 mA / cm 2 10 mA / cm 2 .

[0014] Furthermore, the electrolysis reaction time is 2-5 hours, for example, 2 hours, 3 hours, 4 hours, or 5 hours.

[0015] Further, after the electrolysis reaction, ethyl acetate is added to the reaction solution, with the amount of ethyl acetate being 8-12% of the volume of methanol. The mixture is then filtered to obtain an alkyl-substituted imidazole chloride ionic liquid. The solvent methanol is then removed, and the target product precipitates from the reaction solution. The precipitate is collected by filtration, washed, and dried to obtain the promoter NS. Methanol has a low boiling point and can be removed by distillation or vacuum distillation. As methanol is removed, precipitates continuously form. The precipitate is washed with water and petroleum ether.

[0016] The present invention has the following beneficial effects: 1. The reaction process is simple, and the catalysts all have well-defined molecular structures, which is beneficial for studying the catalytic reaction mechanism.

[0017] 2. The synthesis process is simple, mild, green, non-toxic and pollution-free, and has a high product yield, which greatly ensures the possibility of scaling up production in industry.

[0018] 3. Using methanol as a single solvent, the price is only 1 / 4 of that of acetonitrile, resulting in low cost. Furthermore, methanol is an environmentally friendly solvent, enabling clean production.

[0019] 4. Using simple, readily available, and recyclable alkyl-substituted imidazole chloride ionic liquids as catalysts results in higher catalytic activity, lower usage, and lower cost compared to hydrochloric acid. This enables highly efficient catalysis in methanol solvents and achieves high yields in methanol, making it a key technology for green and clean production.

[0020] 5. The reaction difficulty is further reduced, and high yield production of NS can be achieved at lower current densities and at room temperature and pressure. Attached Figure Description

[0021] Figure 1 The image shows the hydrogen NMR spectrum of the product obtained in Example 5. Detailed Implementation

[0022] The following description illustrates exemplary embodiments of the present invention, including various details to aid understanding, and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions, operations, and structures are omitted in the following description.

[0023] Unless otherwise defined, the technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art. While similar or identical methods and materials may be applied in experimental or practical applications, the present invention describes materials and methods hereinafter. In case of conflict, the definitions included herein shall prevail.

[0024] In the following examples, 1-butyl-3-methylimidazolium chloride was purchased from Shanghai McLean Biochemical Technology Co., Ltd., 1-propyl-3-methylimidazolium chloride was purchased from Shanghai Adamas Reagent Co., Ltd., and 1-ethyl-3-methylimidazolium chloride was purchased from Beijing Anaiji Energy Engineering Technology Co., Ltd.

[0025] In the following examples and comparative examples, the product yield was calculated as follows: Yield = Product quality / (Product molecular weight) (Molar amount of accelerator M) 100.

[0026] Example 1 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 6 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 76% based on accelerator M.

[0027] Example 2 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 12 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 86% based on accelerator M.

[0028] Example 3 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 94% based on accelerator M.

[0029] Example 4 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.4 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 84% ​​based on accelerator M.

[0030] Example 5 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.8 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 98% based on accelerator M.

[0031] Example 6 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.5 mmol of tetrabutylammonium bromide, 0.4 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 90% based on accelerator M.

[0032] Example 7 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 2.0 mmol of tetrabutylammonium bromide, 0.4 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 93% based on accelerator M.

[0033] Example 8 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 10 mA / cm². 2 Electrolyze in an electrolytic cell for 2 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 78% based on accelerator M.

[0034] Example 9 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 3 mA / cm². 2 Electrolyze in an electrolytic cell for 5 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 83% based on accelerator M.

[0035] Example 10 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of 1-butyl-3-methylimidazolium chloride, and 8 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.8 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 90% based on accelerator M.

[0036] Example 11 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of 1-butyl-3-methylimidazolium chloride, and 10 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 1.0 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 88% based on accelerator M.

[0037] Example 12 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of 1-propyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-propyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 84% ​​based on accelerator M.

[0038] Example 13 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of 1-ethyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-ethyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 79% based on accelerator M.

[0039] Example 14 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetraethylammonium bromide, 0.6 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 82% based on accelerator M.

[0040] Example 15 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of cetyl ammonium bromide, 0.6 mmol of 1-butyl-3-methylimidazolium chloride, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 Electrolyze in an electrolytic cell for 4 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-butyl-3-methylimidazolium chloride, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 85% based on accelerator M.

[0041] Comparative Example 1 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 5 mA / cm². 2 The product was electrolyzed in an electrolytic cell for 4 h, followed by vacuum distillation to remove methanol. The crude product precipitated out and was washed with water and petroleum ether and dried to obtain sulfidation accelerator NS. The product yield was 22% based on accelerator M.

[0042] Comparative Example 2 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of hydrogen chloride (provided by 37 wt% hydrochloric acid), and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using carbon plates as electrodes, the current density was adjusted to 4 mA / cm². 2 The product was electrolyzed in an electrolytic cell for 4 hours, followed by vacuum distillation to remove methanol. The crude product precipitated out and was washed with water and petroleum ether and dried to obtain sulfidation accelerator NS. The product yield was 68% based on accelerator M.

[0043] Comparative Example 3 A method for the electrochemical synthesis of sulfidation accelerator NS in methanol solvent includes the following steps: At room temperature and pressure, 2 mmol of accelerator M, 16 mmol of tert-butylamine, 1.0 mmol of tetrabutylammonium bromide, 0.6 mmol of 1-propyl-3-methylimidazolium methanesulfonate, and 9 mL of methanol were stirred until homogeneous; with a surface area of ​​2 cm²... 2 Using graphite plates as electrodes, the current density was adjusted to 3 mA / cm². 2 Electrolyze in an electrolytic cell for 5 h, then add 0.9 mL of ethyl acetate, filter to obtain 1-propyl-3-methylimidazolium methanesulfonate, then remove methanol by vacuum distillation, the crude product precipitates out, wash the crude product with water and petroleum ether, and dry to obtain sulfidation accelerator NS, the product yield of which is 42% based on accelerator M.

[0044] The results above demonstrate that, in methanol solvent, using quaternary ammonium salts as electrolytes and alkyl-substituted imidazole chloride ionic liquids as catalysts exhibits highly efficient reactivity for the electrochemical synthesis of sulfuric acid (NS). Under relatively low current densities, it can effectively catalyze the conversion of 2-mercaptobenzothiazole and tert-butylamine into the sulfurization accelerator NS, achieving a yield of up to 98%. These results indicate that this method for the electrochemical synthesis of NS in methanol solvent demonstrates high selectivity and produces no excess waste liquid, highlighting its ability for green electrocatalytic synthesis and solving the scientific challenges of high energy consumption and high pollution in the chemical synthesis of NS.

[0045] Of course, the above embodiments of the present invention are merely illustrative examples and are not intended to limit the specific implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above examples. It is impossible to provide detailed examples of all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for the electrochemical synthesis of sulfidation accelerator NS, characterized in that: Includes the following steps: 2-Mercaptobenzothiazole, tert-butylamine, electrolyte, catalyst and methanol are mixed and electrolyzed, followed by post-treatment to obtain sulfidation accelerator NS; the catalyst is an alkyl-substituted imidazole chloride ionic liquid.

2. The method according to claim 1, characterized in that: The alkyl-substituted imidazolium chloride ionic liquid includes one of 1-butyl-3-methylimidazolium chloride, 1-propyl-3-methylimidazolium chloride, and 1-ethyl-3-methylimidazolium chloride.

3. The method according to claim 1, characterized in that: The electrolyte is a quaternary ammonium salt.

4. The method according to claim 3, characterized in that: The quaternary ammonium salts include one of tetraethylammonium bromide, hexadecylammonium bromide, and tetrabutylammonium bromide.

5. The method according to claim 1, characterized in that: The molar ratio of 2-mercaptobenzothiazole to tert-butylamine is 1:1.5-8, preferably 1:3-8.

6. The method according to claim 1 or 2, characterized in that: The molar ratio of 2-mercaptobenzothiazole to the catalyst is 1:0.05-0.5, preferably 1:0.15-0.

5.

7. The method according to claim 1, 3 or 4, characterized in that: The molar ratio of 2-mercaptobenzothiazole to electrolyte is 1:0.25-1, preferably 1:0.5-1.

8. The method according to claim 1, characterized in that: The molar ratio of 2-mercaptobenzothiazole to methanol is 1:80-125, preferably 1:90-115.

9. The method according to claim 1, characterized in that: The current density for electrolysis is 3–10 mA / cm². 2 .

10. The method according to claim 1, characterized in that: The electrode materials used in electrolysis are carbon plates or graphite plates.

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