A clean synthesis of dithiodiglycol

Abstract

This application relates to the field of organic synthesis technology, specifically disclosing a clean synthesis method for dithiodiethylene glycol. Using β-mercaptoethanol (2-mercaptoethanol) as a starting material, this application efficiently prepares dithiodiethylene glycol via oxidative coupling. This clean synthesis method uses hydrogen peroxide as a green oxidant, achieving highly selective oxidative coupling under mild conditions. It has advantages such as simple process, high safety, environmental friendliness, easy operation, and excellent product yield, making it suitable for large-scale industrial production.

Description

Technical Field

[0001] This application relates to the field of organic synthesis technology, and in particular to a clean synthesis method for dithiodiethylene glycol. Background Technology

[0002] Dithiodiethylene glycol is an important sulfur-containing bifunctional organic compound that is widely used in the synthesis of pharmaceutical intermediates, surfactants, polymer modifiers, pesticides, and functional materials.

[0003] Currently, the main industrial synthesis routes are as follows: 1. Chloroethanol and sodium sulfide method: This reaction produces a large amount of inorganic salt byproducts, which are highly corrosive and generate difficult-to-treat wastewater, posing a significant environmental burden. 2. Strong oxidant oxidation method (such as concentrated nitric acid, potassium permanganate, etc.): This reaction is vigorous, with concentrated exothermic reactions, making temperature control difficult. It is prone to over-oxidation, generating sulfonic acid impurities and producing toxic waste liquid, which does not meet green chemistry standards. 3. Electrochemical oxidation or transition metal catalytic oxidation: These reactions require high investment in equipment and expensive catalysts, and pose a risk of heavy metal residues, hindering product purification and large-scale application.

[0004] Patent publication number CN102001978A discloses a process for synthesizing dithiodiethylene glycol. This process uses 2-mercaptoethanol as a raw material and potassium persulfate as an oxidant in a bromide ion liquid. Although the reaction time is short, the resulting dithiodiethylene glycol solution requires vacuum distillation and purification processes, resulting in a yield of only 84%. Patent publication number CN107311900A discloses a method for synthesizing dithiodiethylene glycol using taurine as a catalyst. This method uses 2-mercaptoethanol as a raw material and hydrogen peroxide as an oxidant, employing taurine as a catalyst to synthesize dithiodiethylene glycol. While this method increases the rate, it requires further extraction and washing compared to the present method, making the process complex and not conducive to simplified operation.

[0005] Therefore, it is necessary to develop a novel synthesis process that features mild reaction conditions, no heavy metal involvement, high yield, simple process, environmental friendliness, and industrialization potential to overcome the many bottlenecks in existing technologies. Summary of the Invention

[0006] The purpose of this application is to overcome the shortcomings of the prior art and provide a clean method for the synthesis of dithiodiethylene glycol.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: This application provides a clean synthesis method for dithiodiethylene glycol, comprising the following steps: S1. Add 2-mercaptoethanol to the reaction vessel to carry out the reaction, add hydrogen peroxide dropwise to carry out the reaction, control the reaction temperature at 100~120℃, and then carry out the constant temperature reaction. S2. After the isothermal reaction is completed, vacuum distillation is then carried out to remove water and obtain dithiodiethylene glycol.

[0008] This application describes a method for the efficient preparation of dithiodiglycol (also known as dithiodiglycol) via oxidative coupling, using β-mercaptoethanol (2-mercaptoethanol) as the starting material. This clean synthetic method employs hydrogen peroxide as a green oxidant, achieving highly selective oxidative coupling under mild conditions. It offers advantages such as simple process, high safety, environmental friendliness, ease of operation, and excellent product yield, making it suitable for large-scale industrial production.

[0009] In a preferred embodiment of the clean synthesis method of dithiodiethylene glycol described in this application, the temperature of the controlled reaction is 115°C.

[0010] The 2-mercaptoethanol of this application undergoes a selective oxidative coupling reaction with hydrogen peroxide at the specific temperature mentioned above to generate the target product, dithiodiethylene glycol, with a purity of up to 99% and a yield of 99%.

[0011] In a preferred embodiment of the clean synthesis method of dithiodiethylene glycol described in this application, in step S1, the molar ratio of 2-mercaptoethanol to hydrogen peroxide is (2~2.5):1.

[0012] As a preferred embodiment of the clean synthesis method of dithiodiethylene glycol described in this application, in step S1, the molar ratio of 2-mercaptoethanol to hydrogen peroxide is 2:1. This molar ratio can improve the conversion rate of raw materials and the yield of the target product, suppress the occurrence of side reactions, save raw materials, reduce costs, and make the reaction conditions easier to control.

[0013] In a preferred embodiment of the clean synthesis method of dithiodiethylene glycol described in this application, the hydrogen peroxide has a mass fraction of 20% to 30%.

[0014] This application uses hydrogen peroxide within the above-mentioned mass fraction range, which can better react with 2-mercaptoethanol in a selective oxidative coupling reaction. The reduction product is only water, with no harmful emissions. The clean synthesis method provided in this application does not use toxic solvents or heavy metal catalysts. The entire process is clean and safe, environmentally friendly, and meets green chemistry standards.

[0015] As a preferred embodiment of the clean synthesis method of dithiodiethylene glycol described in this application, the hydrogen peroxide has a mass fraction of 30%. 30% hydrogen peroxide has strong oxidizing power and low water content, which can reduce side reactions and post-processing burden. It is also economical in dosage, convenient for storage and transportation, and has high purity, making it suitable for experimental and industrial process requirements.

[0016] In a preferred embodiment of the clean synthesis method for dithiodiethylene glycol described in this application, the reaction time is controlled to be 1.5 to 2 hours.

[0017] In a preferred embodiment of the clean synthesis method of dithiodiethylene glycol described in this application, the temperature of the isothermal reaction is 100~120°C.

[0018] In a preferred embodiment of the clean synthesis method of dithiodiethylene glycol described in this application, the isothermal reaction time is 3-3.5 h.

[0019] By employing the aforementioned controlled reaction conditions and isothermal reaction conditions, this application can better achieve selective oxidative coupling reaction, generating the target product dithiodiethylene glycol with a purity of up to 99% and a yield of 99%.

[0020] Compared with the prior art, this application has the following beneficial effects: This application provides a clean synthesis method for dithiodiethylene glycol, using β-mercaptoethanol (2-mercaptoethanol) as the starting material and hydrogen peroxide as the oxidant. The reduction product is only water, with no harmful emissions. It does not use toxic solvents or heavy metal catalysts, making the entire process clean, safe, and environmentally friendly, meeting green chemistry standards. The absence of catalyst not only saves production costs but also eliminates byproducts. The absence of extraction and washing reduces the reaction steps and improves production efficiency. The reaction proceeds at room temperature and pressure, with stable exothermic action, eliminating the need for complex temperature control systems and ensuring safe and reliable operation. The absence of intermediate separation steps makes it suitable for continuous and industrial production, yielding high yields and possessing industrial potential. Attached Figure Description

[0021] Figure 1 This is the mass spectrum of dithiodiethylene glycol. Detailed Implementation

[0022] To better illustrate the purpose, technical solution, and advantages of this application, the following description will be provided in conjunction with the accompanying drawings and specific embodiments.

[0023] In the following examples and comparative examples, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified. Furthermore, the raw materials used in each parallel experiment are the same.

[0024] Example 1: A clean synthesis method for dithiodiethylene glycol This embodiment provides a clean synthesis method for dithiodiethylene glycol, including the following steps: S1. First, weigh 200g of 2-mercaptoethanol and add it to the reaction vessel at once. Heat the vessel and start stirring. Then, weigh 145g of 30% hydrogen peroxide. When the temperature inside the vessel reaches the predetermined temperature of 60℃, start adding hydrogen peroxide dropwise to carry out the reaction. Control the reaction temperature at 115℃ and the reaction time at 2h. After the reaction is completed, keep the temperature constant for 3.5h. The molar ratio of 2-mercaptoethanol to hydrogen peroxide is 2:1. S2. After the isothermal reaction is completed, the product and water are separated by vacuum distillation to remove water and obtain dithiodiethylene glycol with a yield of 99%.

[0025] Example 2: A clean synthesis method for dithiodiethylene glycol This embodiment provides a clean synthesis method for dithiodiethylene glycol, including the following steps: S1. First, weigh 250g of 2-mercaptoethanol and add it to the reaction vessel at once. Heat the vessel and start stirring. Then, weigh 145g of 30% hydrogen peroxide. When the temperature inside the vessel reaches the predetermined temperature of 60℃, start adding hydrogen peroxide dropwise to carry out the reaction. Control the reaction temperature at 115℃ and the reaction time at 2h. After the reaction is completed, keep the temperature constant for 3.5h. The molar ratio of 2-mercaptoethanol to hydrogen peroxide is 2.5:1. S2. After the isothermal reaction is completed, the product and water are separated by vacuum distillation to remove water and obtain dithiodiethylene glycol with a yield of 92%.

[0026] Example 3: A clean synthesis method for dithiodiethylene glycol This embodiment provides a clean synthesis method for dithiodiethylene glycol, including the following steps: S1. First, weigh 200g of 2-mercaptoethanol and add it to the reaction vessel at once. Heat the vessel and start stirring. Then, weigh 217.5g of 20% hydrogen peroxide. When the temperature inside the vessel reaches the predetermined temperature of 60℃, start adding hydrogen peroxide as an oxidant to carry out the reaction. Control the reaction temperature at 115℃ and the reaction time at 2h. After the reaction is completed, keep the temperature constant for 3.5h. The molar ratio of 2-mercaptoethanol to hydrogen peroxide is 2:1. S2. After the isothermal reaction is completed, the product and water are separated by vacuum distillation to remove water and obtain dithiodiethylene glycol with a yield of 87%.

[0027] Example 4: A clean synthesis method for dithiodiethylene glycol Example 4 provides a clean synthesis method for dithiodiethylene glycol, comprising the following steps: S1. Add 200g of 2-mercaptoethanol to the reaction vessel and react. Add 290g of 15% hydrogen peroxide dropwise and react. Control the reaction temperature at 115℃ and the reaction time at 2h. After the reaction is completed, keep the temperature constant for 3.5h. The molar ratio of 2-mercaptoethanol to hydrogen peroxide is 2:1. S2. After the isothermal reaction is completed, the product and water are separated by vacuum distillation to remove water and obtain dithiodiethylene glycol with a yield of 80%.

[0028] Comparative Example 1: A Clean Synthesis Method for Dithiodiethylene Glycol Comparative Example 1 provides a clean synthetic method for dithiodiethylene glycol, comprising the following steps: S1. Add 200g of 2-mercaptoethanol to the reaction vessel and react. Add 145g of 30% hydrogen peroxide dropwise and react. Control the reaction temperature at 40℃ and the reaction time at 2h. After the reaction is completed, keep the temperature constant for 3.5h. The molar ratio of 2-mercaptoethanol to hydrogen peroxide is 2:1. S2. After the isothermal reaction is completed, the product and water are separated by vacuum distillation to remove water and obtain dithiodiethylene glycol with a yield of 55%.

[0029] Comparative Example 2: A Clean Synthesis Method for Dithiodiethylene Glycol Comparative Example 2 provides a clean synthetic method for dithiodiethylene glycol, comprising the following steps: S1. Add 200g of 2-mercaptoethanol to the reaction vessel and react. Add 145g of 30% hydrogen peroxide dropwise and react. Control the reaction temperature at 80℃ and the reaction time at 2h. After the reaction is completed, keep the temperature constant for 3.5h. The molar ratio of 2-mercaptoethanol to hydrogen peroxide is 2:1. S2. After the isothermal reaction is completed, the product and water are separated by vacuum distillation to remove water and obtain dithiodiethylene glycol with a yield of 70%.

[0030] Comparative Example 3: A Clean Synthesis Method for Dithiodiethylene Glycol Comparative Example 3 provides a clean synthetic method for dithiodiethylene glycol, comprising the following steps: S1. Add 200g of 2-mercaptoethanol to the reaction vessel and react. Add 145g of 30% hydrogen peroxide dropwise and react. Control the reaction temperature at 140℃ and the reaction time at 2h. After the reaction is completed, keep the temperature constant for 3.5h. The molar ratio of 2-mercaptoethanol to hydrogen peroxide is 2:1. S2. After the isothermal reaction is completed, the product and water are separated by vacuum distillation to remove water and obtain dithiodiethylene glycol with a yield of 78%.

[0031] Comparative Example 4: A Clean Synthesis Method for Dithiodiethylene Glycol Comparative Example 4 provides a clean synthetic method for dithiodiethylene glycol, comprising the following steps: S1. Add 200g of 2-mercaptoethanol to the reaction vessel at once, heat the vessel, and start stirring. Then weigh out 287L of 10% ozone. When the temperature inside the vessel reaches the predetermined temperature, start introducing the oxidant ozone. Control the reaction temperature at 140℃ and the reaction time at 2h. After the reaction is completed, keep the temperature constant for 3.5h. The molar ratio of 2-mercaptoethanol to hydrogen peroxide is 2:1. S2. After the isothermal reaction is completed, the product and water are separated by vacuum distillation to remove water and obtain dithiodiethylene glycol with a yield of 66%.

[0032] The mass spectrum of the obtained dithiodiethylene glycol is as follows: Figure 1 As shown.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A process for the clean synthesis of dithiodiglycol, characterized in that, Includes the following steps: S1. Add 2-mercaptoethanol to the reaction vessel to carry out the reaction, add hydrogen peroxide dropwise to carry out the reaction, control the reaction temperature at 100~120℃, and then carry out the constant temperature reaction. S2. After the isothermal reaction is completed, vacuum distillation is then carried out to remove water and obtain dithiodiethylene glycol.

2. The clean synthesis method of dithiodiethylene glycol as described in claim 1, characterized in that, The temperature of the controlled reaction is 115°C.

3. The clean synthesis method of dithiodiethylene glycol as described in claim 1, characterized in that, In step S1, the molar ratio of 2-mercaptoethanol to hydrogen peroxide is (2~2.5):

1.

4. The clean synthesis method of dithiodiethylene glycol as described in claim 3, characterized in that, In step S1, the molar ratio of 2-mercaptoethanol to hydrogen peroxide is 2:

1.

5. The clean synthesis method of dithiodiethylene glycol as described in claim 1, characterized in that, The hydrogen peroxide has a mass fraction of 20% to 30%.

6. The clean synthesis method of dithiodiethylene glycol as described in claim 5, characterized in that, The hydrogen peroxide has a mass fraction of 30%.

7. The clean synthesis method of dithiodiethylene glycol as described in claim 1, characterized in that, The reaction time was controlled to be 1.5-2 h.

8. The clean synthesis method of dithiodiethylene glycol as described in claim 1, characterized in that, The temperature of the isothermal reaction is 100~120℃.

9. The clean synthesis method of dithiodiethylene glycol as described in claim 1, characterized in that, The isothermal reaction time is 3~3.5 h.

10. Dithiodiethylene glycol prepared by the clean synthesis method of dithiodiethylene glycol according to any one of claims 1 to 9.

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