Process for the metal-catalyzed synthesis of 2-mercaptothiazolines

Abstract

The application provides a method for synthesizing 2-mercaptothiazoline by metal catalysis, and belongs to the technical field of organic synthesis, wherein the step for synthesizing 2-mercaptothiazoline comprises the following steps: adding ammonia water into a mixed solution of ethanol and carbon disulfide at a predetermined temperature, and obtaining a first reaction solution after sufficient stirring; adding an oxidized metal mixed catalyst into the first reaction solution, and obtaining a second reaction solution after sufficient reaction; adding an azeotropic reagent into the second reaction solution, and performing heating reflux treatment, thereby obtaining a third reaction solution; adding a solvent into the third reaction solution, and sequentially performing heating treatment and cooling recrystallization treatment, thereby obtaining 2-mercaptothiazoline after solid-liquid separation. Through the above method, the 2-mercaptothiazoline with high yield and high purity can be obtained by using cheap and easily obtained raw materials with high safety and a simple process, the needs of industrial production are fully met, and the method has a good practical application prospect.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and specifically to a method for the metal-catalyzed synthesis of 2-mercaptothiazoline. Background Technology

[0002] 2-Mercaptothiazoline is a sulfur-containing heterocyclic compound that combines the stability of the thiazoline ring with the reactivity of the thiol group, making it widely used in pharmaceuticals, industry, and other fields. For example, 2-mercaptothiazoline can be used as a raw material to produce cysteine, and it can also be used as an intermediate in acid copper plating to improve the physical properties of lithium-ion battery copper foil.

[0003] Currently, there are three main methods for synthesizing 2-mercaptothiazoline: Method 1: First, ethanolamine is esterified with concentrated sulfuric acid, and then reacted with carbon disulfide to obtain 2-mercaptothiazoline; Method 2: First, ethanolamine and carbon disulfide undergo an addition reaction at high temperature, then concentrated hydrochloric acid is added for acidification and dehydration to obtain the target product; Method 3: Directly react ethyleneimine and carbon disulfide to obtain the target product; Of the methods described above, Method 1 generates a large amount of sodium sulfate waste, resulting in high treatment costs; Method 2 uses concentrated hydrochloric acid, which requires sophisticated equipment, and neutralizing the generated waste HCl also produces a large amount of sodium chloride waste; Method 3 uses ethyleneimine, which is highly toxic and flammable, posing a significant threat to production safety. Furthermore, existing methods for synthesizing 2-mercaptothiazoline typically require the use of ethanolamine (ethyleneimine in Method 3 is also obtained through the reaction of ethanolamine), and the cost of ethanolamine usually accounts for more than 80% of the total raw material cost for synthesizing 2-mercaptothiazoline, leading to high synthesis costs.

[0004] In view of this, it is necessary to provide a more economical, safe, and green process for synthesizing 2-mercaptothiazoline. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides a method for the metal-catalyzed synthesis of 2-mercaptothiazoline. By designing a stepwise reaction, carbon disulfide and ammonia are first reacted in ethanol, and then a catalyst is added to carry out the catalytic reaction. After obtaining the addition product, 2-mercaptothiazoline can be obtained by azeotropic reagent treatment, heating, cooling and recrystallization. The raw materials used in the entire synthesis process are inexpensive and readily available, the synthesis process does not produce waste salt, and high-purity 2-mercaptothiazoline can be obtained in high yield, which is suitable for industrial production.

[0006] This application provides a method for the metal-catalyzed synthesis of 2-mercaptothiazoline, comprising the following steps: S1. At a predetermined temperature, ammonia water is added to a mixed solution of ethanol and carbon disulfide, and the mixture is stirred thoroughly to obtain the first reaction solution. S2. Add a mixed catalyst of metal oxides to the first reaction solution, and after the reaction is complete, obtain the second reaction solution; S3. Add an azeotropic reagent to the second reaction solution and heat under reflux to obtain a third reaction solution; S4. Add solvent to the third reaction solution, and perform heating treatment and cooling recrystallization treatment in sequence. After solid-liquid separation, 2-mercaptothiazoline is obtained.

[0007] In some embodiments, in step S1, the mass concentration of ammonia in the ammonia solution is 20% to 28%, and the mass ratio of carbon disulfide to ammonia in the ammonia solution is 4.4:1 to 4.9:1.

[0008] In some embodiments, in step S1, the mixed solution is formed by mixing carbon disulfide and ethanol solution, wherein the volume ratio of carbon disulfide to ethanol solution is 1:5 to 1:10; and the volume concentration of ethanol in the ethanol solution is 85% to 95%.

[0009] In some embodiments, in step S1, the predetermined temperature is 0~10℃; the time for thorough stirring is 1~2h, and the temperature during stirring is 0~20℃.

[0010] In some embodiments, in step S2, the mixed catalyst of oxide metals includes at least two of copper oxide, zinc oxide, nickel oxide, silver oxide, and aluminum oxide.

[0011] In some embodiments, in step S2, the reaction temperature for a complete reaction is 10~40°C, and the reaction time is 5~10h.

[0012] In some embodiments, in step S3, the azeotropic reagent includes at least one of chloroform, toluene, xylene, dichloroethane, ethanol, and formic acid.

[0013] In some embodiments, step S3, the heating and reflux treatment includes: refluxing at 60~100°C for 3~6 hours.

[0014] In some embodiments, in step S4, the solvent includes at least one of methanol, water, acetonitrile, and acetone; the volume ratio of the solvent to the carbon disulfide is 10:1 to 24:1.

[0015] In some embodiments, in step S4, the temperature of the heat treatment is 80~98°C.

[0016] The beneficial effects of this application are as follows: The method for synthesizing 2-mercaptothiazoline using metal catalysis provided in this application involves a stepwise reaction. First, carbon disulfide and ammonia are reacted in ethanol to generate dithiocarbamic acid. Then, a mixed metal oxide catalyst is added, utilizing the ethanol in the first reaction solution to generate formaldehyde in situ, which participates in the reaction to obtain the addition product. Next, an azeotropic reagent is introduced, and the mixture is heated under reflux. A solvent is then added, followed by heating, cooling, recrystallization, and solid-liquid separation to obtain 2-mercaptothiazoline. Based on the method provided in this application, the synthesis of 2-mercaptothiazoline does not require the use of ethanolamine as a raw material. Furthermore, all raw materials used in this application are low-cost and highly safe, and the synthesis process does not generate waste salts, effectively reducing raw material costs and waste disposal costs. Simultaneously, the method provided in this application can obtain high-purity 2-mercaptothiazoline with a high yield, fully meeting the needs of industrial production and showing good practical application prospects.

[0017] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Detailed Implementation

[0018] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0019] 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 this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion.

[0020] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] To achieve a more economical, safe, and environmentally friendly synthesis of 2-mercaptothiazoline, this application provides a metal-catalyzed method for synthesizing 2-mercaptothiazoline. Through a stepwise reaction design, carbon disulfide and ammonia are first reacted in ethanol, followed by the addition of a catalyst for catalytic reaction. The resulting addition product is then treated with an azeotropic reagent, heated, and recrystallized after cooling to obtain 2-mercaptothiazoline. The corresponding technical route is as follows: The raw materials used in the entire synthesis process are inexpensive and readily available, the synthesis process does not produce waste salt, and it can obtain high-purity 2-mercaptothiazoline in high yield, making it suitable for industrial production.

[0023] Specifically, this application provides a method for the metal-catalyzed synthesis of 2-mercaptothiazoline, comprising the following steps: S1. At a predetermined temperature, ammonia water is added to a mixed solution of ethanol and carbon disulfide, and the mixture is stirred thoroughly to obtain the first reaction solution. S2. Add a mixed catalyst of metal oxides to the first reaction solution, and after the reaction is complete, obtain the second reaction solution; S3. Add an azeotropic reagent to the second reaction solution and heat under reflux to obtain the third reaction solution; S4. Add solvent to the third reaction solution, and perform heating and cooling recrystallization treatment in sequence. After solid-liquid separation, 2-mercaptothiazoline is obtained.

[0024] In the technical solution of this application embodiment, by first preparing a mixed solution containing ethanol and carbon disulfide, then adding ammonia to the mixed solution, and controlling the corresponding reaction conditions, carbon disulfide reacts with ammonia to generate dithiocarbamic acid, thereby obtaining a first reaction solution containing dithiocarbamic acid and ethanol. Based on this, by adding a mixed catalyst of metal oxides to the first reaction solution, the ethanol in the first reaction solution can be oxidized in situ to acetaldehyde, which then undergoes an addition reaction with dithiocarbamic acid to obtain an addition product. Afterwards, an azeotropic reagent is introduced for heating under reflux, followed by the addition of a solvent. After heating, cooling, recrystallization, and solid-liquid separation, 2-mercaptothiazoline is obtained. Based on the method provided in this application, ethanolamine is not required as a raw material in the synthesis of 2-mercaptothiazoline. Moreover, all the raw materials used in this application are low in cost and high in safety. The synthesis process does not generate waste salt, which effectively reduces the cost of raw materials and waste disposal. At the same time, the method provided in this application can obtain high-purity 2-mercaptothiazoline with a high yield, which has good prospects for practical application.

[0025] Furthermore, in some embodiments, in step S1, the mixed solution is composed of carbon disulfide and ethanol solution, with a volume ratio of carbon disulfide to ethanol solution of 1:5 to 1:10; the volume concentration of ethanol in the ethanol solution is 85% to 95%; the mass concentration of ammonia in the ammonia solution is 20% to 28%, and the mass ratio of carbon disulfide to ammonia in the ammonia solution is 4.4:1 to 4.9:1; the predetermined temperature is 0 to 10°C; the stirring time is 1 to 2 hours, and the stirring temperature is 0 to 20°C.

[0026] In the technical solution of this application embodiment, the ethanol solution is specifically an aqueous solution of ethanol. This application embodiment first prepares a mixed solution of carbon disulfide and ethanol, then adds ammonia to the mixed solution. Simultaneously, by limiting the proportions of each raw material and the corresponding reaction conditions during the reaction process, the reaction process of carbon disulfide and ammonia can be effectively controlled, avoiding excess ammonia and facilitating the formation of dithiocarbamic acid. At the same time, the ethanol in the mixed solution can fully mix with the generated dithiocarbamic acid, and under the action of a subsequently added catalyst, acetaldehyde is generated in situ, which then fully reacts with the dithiocarbamic acid for efficient synthesis of 2-mercaptothiazoline.

[0027] Furthermore, in some embodiments, in step S1, the drop rate of ammonia is preferably 5-10 mL / min, which is more conducive to controlling the above reaction.

[0028] Furthermore, in some embodiments, in step S2, the mixed metal oxide catalyst includes a support and a catalytic component supported on the support. The catalytic component includes at least two metal oxides, which may be copper oxide, zinc oxide, nickel oxide, silver oxide, or aluminum oxide. The support may include any one of zeolite, silica, diatomaceous earth, or diatomite.

[0029] Furthermore, the catalytic components supported on the support specifically include a first metal oxide and a second metal oxide, with the total mass of the first metal oxide and the second metal oxide accounting for more than 50% of the total mass of all catalytic components on the support. The mass ratio of the first metal oxide to the second metal oxide is preferably 1:2 to 2:1. The first metal oxide and the second metal oxide are any two of copper oxide, zinc oxide, nickel oxide, silver oxide, and aluminum oxide; more preferably, the first metal oxide is copper oxide, and the second metal oxide is either zinc oxide or aluminum oxide. This configuration allows the synergistic effect of copper oxide and the amphoteric metal catalyst (zinc oxide or aluminum oxide) to promote the conversion of ethanol to acetaldehyde while simultaneously increasing the reactivity of acetaldehyde with dithiocarbamate, thereby effectively improving the final product yield and purity.

[0030] In the technical solution of this application embodiment, by using the above-mentioned mixed metal oxide catalyst, ethanol in the first reaction solution can be oxidized in situ to generate acetaldehyde, and acetaldehyde can undergo an addition reaction with dithiocarbamic acid in the first reaction solution under the action of the catalyst to obtain an addition product. Specifically, the amount of the mixed metal oxide catalyst is determined according to the amount of carbon disulfide, and preferably the total mass of the catalytic components in the catalyst accounts for 0.5% to 2% of the mass of carbon disulfide.

[0031] Furthermore, in some embodiments, in step S2, the reaction temperature for a full reaction is 10~40°C, and the reaction time is 5~10h, so that the oxidation reaction of ethanol and the addition reaction of acetaldehyde with dithiocarbamate can proceed fully.

[0032] Furthermore, in some embodiments, in step S3, the azeotropic reagent includes at least one selected from chloroform, toluene, xylene, dichloroethane, ethanol, and formic acid to achieve an azeotropic effect. More specifically, in some embodiments, the amount of azeotropic reagent is determined based on the amount of ethanol used in step S1, and preferably, the volume of the azeotropic reagent accounts for 10% to 20% of the volume of ethanol in step S1.

[0033] Furthermore, in some embodiments, step S3, the reflux treatment includes reflux at 60~100°C for 3~6 hours. More specifically, in some embodiments, a fractionator is used to collect the azeotrope during reflux, and heating is stopped when 1 / 3-1 / 5 of the azeotrope remains in the reaction system.

[0034] Furthermore, in some embodiments, in step S4, the solvent includes at least one of methanol, water, acetonitrile, and acetone; the volume ratio of the solvent to carbon disulfide is preferably 10:1 to 24:1.

[0035] Furthermore, in some embodiments, the heating temperature in step S4 is 80~98°C. More specifically, in some embodiments, after the heating treatment, the temperature is slowly lowered for recrystallization, preferably at a cooling rate of 20~26°C / h. After cooling to 20°C, the sample is preferably filtered using filter paper with a pore size of 10~15μm, and the 2-mercaptothiazoline white solid is obtained after filtration.

[0036] Through the above methods, the metal-catalyzed synthesis of 2-mercaptothiazoline provided in this application can obtain 2-mercaptothiazoline with a purity of 99.5% and a yield of 96%, which is suitable for industrial production.

[0037] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0038] Example 1 This embodiment provides a method for the metal-catalyzed synthesis of 2-mercaptothiazoline, comprising the following steps: S1. At 0℃, add 20mL of carbon disulfide (mass 25.2g) to 100mL of ethanol solution (95% industrial ethanol), stir until homogeneous to obtain a mixed solution; add 23mL of 28% ammonia solution (equivalent to 5.7g of pure ammonia) dropwise to the mixed solution, and after the addition is completed in 3 minutes, stir at 0℃ for 2 hours to obtain the first reaction solution.

[0039] S2. Add a copper oxide-zinc oxide composite catalyst (copper oxide and zinc oxide with mass of 0.25g and 0.25g respectively) with zeolite as a support to the first reaction solution, raise the temperature to 40℃, and react for 5 hours to obtain the second reaction solution.

[0040] S3. Add 20 mL of dichloroethane to the second reaction solution and reflux at 70 °C for 3 hours. Collect the azeotrope using a fractionator. When 1 / 5 of the azeotrope remains in the reaction system, stop heating to obtain the third reaction solution.

[0041] S4. Add 480 mL of water to the third reaction solution, then heat to 98 °C, and then cool at a rate of 26 °C / h for 3 hours to recrystallize. After that, filter the solution at 20 °C using filter paper with a pore size of 10 μm, and then dry it to obtain 35.65 g of 2-mercaptothiazoline, which is a white solid.

[0042] Calculations showed that 25.2g of carbon disulfide could theoretically produce 39.5g of 2-mercaptothiazoline. Testing revealed that the purity of the 2-mercaptothiazoline obtained in this embodiment was 99.4%, meaning the actual mass of pure 2-mercaptothiazoline obtained was 35.4361g. Compared to the theoretical mass, the yield was calculated to be 90%. Therefore, the metal-catalyzed synthesis method for 2-mercaptothiazoline provided in this embodiment can obtain high-purity 2-mercaptothiazoline with a high yield, possessing significant industrial application value.

[0043] Example 2 and Comparative Examples 1-2 Example 2 and Comparative Examples 1-2 respectively provide a method for the metal-catalyzed synthesis of 2-mercaptothiazoline. Compared with Example 1, the only difference is that the volume of ammonia water in step S1 is changed, that is, the mass ratio of carbon disulfide to ammonia in ammonia water is changed. The remaining steps are the same as in Example 1, and will not be described again here.

[0044] The mass ratio of carbon disulfide to ammonia in each example and comparative example, as well as the yield and purity of the obtained 2-mercaptothiazoline, are shown in Table 1.

[0045] Table 1 As shown in Table 1, both excess carbon disulfide and excess ammonia significantly reduce the yield and purity of 2-mercaptothiazoline. This is mainly because excess carbon disulfide or ammonia increases the amount of reaction byproducts in step S1, forming polymers and thus affecting the yield and purity of the final product. This application, by controlling the ratio of carbon disulfide to ammonia, can effectively regulate the reaction in step S1, effectively reduce the formation of byproducts, and thereby improve the yield and purity of the final product.

[0046] Examples 3-4 and Comparative Example 3 Examples 3-4 and Comparative Example 3 respectively provide a method for the metal-catalyzed synthesis of 2-mercaptothiazoline. Compared with Example 1, the only difference is that the temperature conditions in step S1 are changed. The other steps are the same as those in Example 1 and will not be described again here.

[0047] The temperatures used in each example and comparative example, as well as the yield and purity of the obtained 2-mercaptothiazoline, are shown in Table 2.

[0048] Table 2 As can be seen from Table 2, the temperature conditions in step S1 gradually increase, which causes some of the ammonia in the ammonia water to evaporate, resulting in a gradual decrease in yield and purity.

[0049] Example 5 and Comparative Example 4 Example 5 and Comparative Example 4 respectively provide a method for the metal-catalyzed synthesis of 2-mercaptothiazoline. Compared with Example 1, the only difference is that the composition of the catalyst in step S2 is changed. The other steps are the same as in Example 1 and will not be described again here.

[0050] The catalyst composition, yield, and purity of the 2-mercaptothiazoline obtained in each example and comparative example are shown in Table 3.

[0051] Table 3 As shown in Table 3, the combination of copper oxide with amphoteric metal catalysts such as zinc oxide or aluminum oxide effectively improved the reaction yield and purity. If copper oxide is used alone, although it can promote the conversion of ethanol to acetaldehyde in step S2, the low reactivity of acetaldehyde with dithiocarbamate affects the final reaction yield and purity.

[0052] Examples 6-7 and Comparative Examples 5-6 Examples 6-7 and Comparative Examples 5-6 respectively provide a method for the metal-catalyzed synthesis of 2-mercaptothiazoline. Compared with Example 1, the only difference is that the reaction temperature and time in step S2 are changed. The other steps are the same as in Example 1 and will not be described again here.

[0053] The reaction temperatures, times, yields, and purities of the 2-mercaptothiazoline obtained in each example and comparative example are shown in Table 4.

[0054] Table 4 As shown in Table 4, the catalyst exhibits good activity at temperatures ranging from 10 to 40°C. However, the catalyst activity decreases significantly at both low and high temperatures, leading to a reduction in yield and purity.

[0055] Comparative Example 7 This comparative example provides a method for the metal-catalyzed synthesis of 2-mercaptothiazoline. The only difference from Example 1 is that no catalyst was added in step S2, but acetaldehyde in equimolar amounts of ethanol was added. The remaining steps are the same as in Example 1 and will not be repeated here.

[0056] In this comparative example, the yield of 2-mercaptothiazoline was 18%, and the purity was 65.1%, which were significantly lower than those in Example 1.

[0057] Compared to the direct addition of acetaldehyde in Comparative Example 7, Example 1, by first adding ethanol in step S1 and then adding a mixed catalyst of a specific composition of oxide metals in step S2, ensures the smooth progress of the reaction in step S1 while promoting thorough mixing of ethanol and dithiocarbamic acid. In step S2, the catalyst catalyzes the in-situ conversion of ethanol to acetaldehyde, simultaneously accelerating the addition reaction. These two processes work synergistically to ensure complete reaction of acetaldehyde and improve the yield and purity of the reaction product. In Comparative Example 7, the direct use of acetaldehyde without a catalyst results in a very slow addition reaction rate, low conversion rate, and a significant decrease in the yield and purity of the final product.

[0058] In summary, this application provides a method for the metal-catalyzed synthesis of 2-mercaptothiazoline, comprising the following steps: adding ammonia to a mixed solution of ethanol and carbon disulfide at a predetermined temperature, stirring thoroughly to obtain a first reaction solution; adding a mixed metal oxide catalyst to the first reaction solution, reacting thoroughly to obtain a second reaction solution; adding an azeotropic reagent to the second reaction solution, heating under reflux to obtain a third reaction solution; adding a solvent to the third reaction solution, sequentially heating and cooling recrystallization, and separating the solid and liquid phases to obtain 2-mercaptothiazoline. Through this method, this application can obtain high-yield and high-purity 2-mercaptothiazoline using inexpensive, readily available, and safe raw materials with a simple process, fully meeting the needs of industrial production and showing good practical application prospects.

[0059] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for the metal-catalyzed synthesis of 2-mercaptothiazoline, characterized in that, Includes the following steps: S1. At a predetermined temperature, ammonia water is added to a mixed solution of ethanol and carbon disulfide, and the mixture is stirred thoroughly to obtain the first reaction solution. S2. Add a mixed catalyst of metal oxides to the first reaction solution, and after the reaction is complete, obtain the second reaction solution; S3. Add an azeotropic reagent to the second reaction solution and heat under reflux to obtain a third reaction solution; S4. Add solvent to the third reaction solution, and perform heating treatment and cooling recrystallization treatment in sequence. After solid-liquid separation, 2-mercaptothiazoline is obtained.

2. The method for metal-catalyzed synthesis of 2-mercaptothiazoline according to claim 1, characterized in that, In step S1, the mass concentration of ammonia in the ammonia solution is 20%~28%, and the mass ratio of carbon disulfide to ammonia in the ammonia solution is 4.4:1~4.9:

1.

3. The method for metal-catalyzed synthesis of 2-mercaptothiazoline according to claim 1, characterized in that, In step S1, the mixed solution is formed by mixing carbon disulfide and ethanol solution, and the volume ratio of carbon disulfide to ethanol solution is 1:5 to 1:

10. The volume concentration of ethanol in the ethanol solution is 85% to 95%.

4. The method for metal-catalyzed synthesis of 2-mercaptothiazoline according to claim 1, characterized in that, In step S1, the predetermined temperature is 0~10℃; the time for thorough stirring is 1~2h, and the temperature during stirring is 0~20℃.

5. The method for metal-catalyzed synthesis of 2-mercaptothiazoline according to claim 1, characterized in that, In step S2, the mixed catalyst of oxidized metals includes at least two of copper oxide, zinc oxide, nickel oxide, silver oxide, and aluminum oxide.

6. The method for metal-catalyzed synthesis of 2-mercaptothiazoline according to claim 1, characterized in that, In step S2, the reaction temperature for a complete reaction is 10~40℃, and the reaction time is 5~10h.

7. The method for metal-catalyzed synthesis of 2-mercaptothiazoline according to claim 1, characterized in that, In step S3, the azeotropic reagent includes at least one of chloroform, toluene, xylene, dichloroethane, ethanol, and formic acid.

8. The method for metal-catalyzed synthesis of 2-mercaptothiazoline according to claim 1, characterized in that, In step S3, the heating and reflux treatment includes: refluxing at 60~100℃ for 3~6 hours.

9. The method for metal-catalyzed synthesis of 2-mercaptothiazoline according to claim 1, characterized in that, In step S4, the solvent includes at least one of methanol, water, acetonitrile, and acetone; the volume ratio of the solvent to the carbon disulfide is 10:1 to 24:

1.

10. The method for metal-catalyzed synthesis of 2-mercaptothiazoline according to claim 1, characterized in that, In step S4, the temperature of the heat treatment is 80~98℃.

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