A Synthetic Process for Diethylene Glycol Monovinyl Ether

Abstract

This invention discloses a synthesis process for diethylene glycol monovinyl ether, relating to the field of chemical synthesis technology. The synthesis process includes the following steps: first, a diethylene glycol solution containing a catalyst is added to a high-pressure reactor; then, after nitrogen purging and heating, acetylene and diethylene glycol are continuously introduced to react and obtain a feed solution. The feed solution is then separated by vacuum distillation to obtain the product and recover the catalyst. This invention, by optimizing the catalyst ratio and process parameters, achieves efficient and continuous production of diethylene glycol monovinyl ether, offering advantages such as high conversion rate, good selectivity, reusable catalyst, low energy consumption, and minimal waste. It solves the technical problems of high energy consumption and severe pollution in existing processes.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, specifically to a synthesis process for diethylene glycol monovinyl ether. Background Technology

[0002] Diethylene glycol monovinyl ether is a functional organic monomer containing ether bonds and vinyl double bonds. Due to its unique molecular structure, it exhibits excellent chemical properties. It not only has low toxicity and odorless environmental protection characteristics, but also has high reactivity, good solubility and weather resistance, and is widely used in the industrial field.

[0003] Current production processes primarily involve the reaction of acetylene and diethylene glycol. Excess acetylene carries the product out of the reactor in gaseous form, followed by condensation and distillation to obtain diethylene glycol monovinyl ether. However, this process suffers from the following significant problems: 1. Due to the high boiling point of diethylene glycol monovinyl ether, a large amount of acetylene is required for gas-phase entrainment, and even if this portion of the acetylene is recovered, it still consumes a significant amount of energy; 2. Existing processes are complex and generate serious waste problems.

[0004] Therefore, in order to solve the above problems, the present invention proposes a synthesis process for diethylene glycol monovinyl ether. Summary of the Invention

[0005] The purpose of this invention is to provide a synthesis process for diethylene glycol monovinyl ether to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A process for synthesizing diethylene glycol monovinyl ether includes the following steps: S1: Add the diethylene glycol solution containing the catalyst into the high-pressure reactor and mix thoroughly; S2: After nitrogen purging 3-5 times, the temperature is raised to the reaction temperature and maintained stable. S3: Acetylene and diethylene glycol are continuously introduced to react and obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged from the outlet. S4: The feed liquid is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3; S5: Diethylene glycol monovinyl ether crude product is obtained by continuous vacuum distillation.

[0007] Furthermore, in step S1, the amount of catalyst used is 0.5~10% of the mass of diethylene glycol; The catalyst is potassium diethylene glycol.

[0008] Furthermore, in step S2, the reaction temperature is 125~160℃.

[0009] Furthermore, in step S3, the reaction pressure is 0.2~1.0 MPa.

[0010] Furthermore, in step S4, the vacuum degree of the reduced pressure distillation is -0.090 to -0.099 MPa.

[0011] Furthermore, in step S1, the catalyst contains potassium tetraborate, which is prepared by the following process: (1) Add potassium hydroxide to deionized water to obtain a potassium hydroxide solution with a mass concentration of 30-40%, and place it in a dropping funnel; (2) Add boric acid and deionized water to the reaction vessel, heat to 60~80℃ and stir to obtain a boric acid solution with a mass concentration of 15~25%; (3) Mix potassium hydroxide solution and boric acid solution at a stirring speed of 300~500 rpm to obtain potassium tetraborate solution; (4) Heat the potassium tetraborate solution in a water bath at a heating rate of 1~3℃ / min to 80~90℃, stop heating, let it cool naturally to room temperature, let it stand at room temperature for 30~60min, and after a large amount of crystals precipitate, filter it with a Buchner funnel to separate the crystals from the mother liquor. (5) Wash the crystals 3 to 5 times with ice-cold anhydrous ethanol, and dry the crystals in an oven at 50 to 60°C for 2 to 4 hours to obtain potassium tetraborate powder. The molar ratio of boric acid to potassium hydroxide is (4~4.5):1; The amount of potassium tetraborate added is 0-100% of the catalyst mass.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention describes a synthesis process for diethylene glycol monovinyl ether. By optimizing reaction conditions and process flow, the present invention achieves continuous production of diethylene glycol monovinyl ether, which greatly improves production efficiency.

[0013] 2. The synthesis process of diethylene glycol monovinyl ether described in this invention allows for the reuse of the catalyst, reducing raw material costs and waste generation.

[0014] 3. The present invention describes a synthesis process for diethylene glycol monovinyl ether. The vinylization reaction of acetylene with diethylene glycol requires an alkaline catalyst to abstract a proton from the alcohol, forming an alkoxy anion that attacks the acetylene. However, excessively strong alkalinity (such as potassium diethylene glycol) can also catalyze the further reaction of the monovinyl ether produced with a second alcohol molecule, generating the byproduct divinyl ether. The mild alkalinity provided by potassium tetraborate is sufficient to catalyze the target reaction, but it can significantly inhibit the secondary reaction of the monovinyl ether to generate divinyl ether, thereby improving the selectivity of the reaction and making the product purer.

[0015] 4. The synthesis process of diethylene glycol monovinyl ether described in this invention uses a combination of potassium tetraborate and potassium diethylene glycol as catalysts. Potassium diethylene glycol acts as a strong base, which can rapidly initiate the reaction, while potassium tetraborate inhibits the further reaction of the monovinyl ether through its mild alkalinity. This combination has both high reactivity and high selectivity, which can not only rapidly generate the product, but also effectively "lock in" the target product diethylene glycol monovinyl ether to prevent its over-reaction. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] In the following specific implementation: The purity of potassium diethylene glycol is 99%; The purity of diethylene glycol is 99%; The purity of acetylene is 98%; Boric acid has a CAS number of 10043-35-3 and a purity of 99.5%. Potassium hydroxide has a CAS number of 1310-58-3 and a purity of 95%. Anhydrous ethanol has a CAS number of 64-17-5. Commercial potassium tetraborate has a CAS number of 1332-77-0 and a purity of 98%.

[0018] Example 1: A process for synthesizing diethylene glycol monovinyl ether, comprising the following steps: S1: Add the diethylene glycol solution containing the catalyst into the high-pressure reactor and mix thoroughly; the amount of catalyst used is 5% of the mass of the diethylene glycol solution; the catalyst is potassium diethylene glycol. S2: After being purged with nitrogen four times, the temperature is raised to 150℃ and maintained at a stable temperature; S3: Acetylene and diethylene glycol are continuously introduced and reacted at a reaction pressure of 0.6 MPa to obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged. S4: The liquid produced in step S3 is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3; the vacuum degree of vacuum distillation is -0.095 MPa; S5: Diethylene glycol monovinyl ether crude product is obtained by continuous vacuum distillation.

[0019] Example 2: A process for synthesizing diethylene glycol monovinyl ether, comprising the following steps: S1: Add the diethylene glycol solution containing the catalyst into the high-pressure reactor and mix thoroughly; the amount of catalyst used is 0.5% of the mass of the diethylene glycol solution; the catalyst is potassium diethylene glycol. S2: After being purged with nitrogen three times, the temperature is raised to 125℃ and maintained at a stable temperature; S3: Acetylene and diethylene glycol are continuously introduced and reacted at a reaction pressure of 0.2 MPa to obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged. S4: The liquid produced in step S3 is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3; the vacuum degree of vacuum distillation is -0.090 MPa; S5: Diethylene glycol monovinyl ether crude product is obtained by continuous vacuum distillation.

[0020] Example 3: A process for synthesizing diethylene glycol monovinyl ether, comprising the following steps: S1: Add the diethylene glycol solution containing the catalyst into the high-pressure reactor and mix thoroughly; the amount of catalyst used is 10% of the mass of the diethylene glycol solution; the catalyst is potassium diethylene glycol. S2: After being purged with nitrogen 5 times, the temperature is raised to 160℃ and maintained at a stable temperature; S3: Acetylene and diethylene glycol are continuously introduced and reacted at a reaction pressure of 1.0 MPa to obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged. S4: The liquid produced in step S3 is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3; the vacuum degree of vacuum distillation is -0.099 MPa; S5: Diethylene glycol monovinyl ether crude product is obtained by continuous vacuum distillation.

[0021] Example 4: A process for synthesizing diethylene glycol monovinyl ether, comprising the following steps: S1: Add the diethylene glycol solution containing the catalyst into the high-pressure reactor and mix thoroughly; the amount of catalyst used is 5% of the mass of the diethylene glycol solution; the catalyst is potassium tetraborate; S2: After being purged with nitrogen four times, the temperature is raised to 150℃ and maintained at a stable temperature; S3: Acetylene and diethylene glycol are continuously introduced and reacted at a reaction pressure of 0.6 MPa to obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged. S4: The liquid produced in step S3 is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3; the vacuum degree of vacuum distillation is -0.095 MPa; S5: Diethylene glycol monovinyl ether crude product is subjected to continuous vacuum distillation to obtain diethylene glycol monovinyl ether; Potassium tetraborate is prepared by the following process: (1) Add potassium hydroxide to deionized water to obtain a potassium hydroxide solution with a mass concentration of 30%, and place it in a dropping funnel; (2) Add boric acid and deionized water to the reaction vessel, heat to 60°C and stir at 300 rpm to obtain a boric acid solution with a mass concentration of 20%; (3) At a stirring speed of 300 rpm, potassium hydroxide solution and boric acid solution were mixed to obtain potassium tetraborate solution; (4) Heat the potassium tetraborate solution in a water bath at a heating rate of 2℃ / min until it reaches 85℃. Stop heating and allow it to cool naturally to room temperature. Let it stand at room temperature for 60 minutes until a large amount of crystals precipitate. Then filter the solution using a Buchner funnel to separate the crystals from the mother liquor. (5) Wash the crystals four times with ice-cold anhydrous ethanol, and dry the crystals in an oven at 50°C for 4 hours to obtain potassium tetraborate powder. The molar ratio of boric acid to potassium hydroxide is 4:1.

[0022] Example 5: A process for synthesizing diethylene glycol monovinyl ether, comprising the following steps: S1: Add the diethylene glycol solution containing the catalyst into the high-pressure reactor and mix thoroughly; the amount of catalyst is 5% of the mass of the diethylene glycol solution; the catalyst includes potassium tetraborate and potassium diethylene glycol, and the mass ratio of potassium tetraborate to potassium diethylene glycol is 1:2; S2: After being purged with nitrogen four times, the temperature is raised to 150℃ and maintained at a stable temperature; S3: Acetylene and diethylene glycol are continuously introduced and reacted at a reaction pressure of 0.6 MPa to obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged. S4: The liquid produced in step S3 is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3; the vacuum degree of vacuum distillation is -0.095 MPa; S5: Diethylene glycol monovinyl ether crude product is subjected to continuous vacuum distillation to obtain diethylene glycol monovinyl ether; Potassium tetraborate is prepared by the following process: (1) Add potassium hydroxide to deionized water to obtain a potassium hydroxide solution with a mass concentration of 35%, and place it in a dropping funnel; (2) Add boric acid and deionized water to the reaction vessel, heat to 80°C and stir at 200 rpm to obtain a boric acid solution with a mass concentration of 20%; (3) At a stirring speed of 400 rpm, potassium hydroxide solution and boric acid solution were mixed to obtain potassium tetraborate solution; (4) Heat the potassium tetraborate solution in a water bath at a heating rate of 1℃ / min until it reaches 80℃. Stop heating and allow it to cool naturally to room temperature. Let it stand at room temperature for 30 minutes. After a large amount of crystals precipitate, filter the solution using a Buchner funnel to separate the crystals from the mother liquor.

[0023] (5) Wash the crystals three times with ice-cold anhydrous ethanol, and dry the crystals in an oven at 55°C for 3 hours to obtain potassium tetraborate powder. The molar ratio of boric acid to potassium hydroxide is 4.2:1.

[0024] Example 6: A process for synthesizing diethylene glycol monovinyl ether, comprising the following steps: S1: Add the diethylene glycol solution containing the catalyst into the high-pressure reactor and mix thoroughly; the amount of catalyst is 5% of the mass of the diethylene glycol solution; the catalyst includes potassium tetraborate and potassium diethylene glycol, and the mass ratio of potassium tetraborate to potassium diethylene glycol is 2:1; S2: After being purged with nitrogen four times, the temperature is raised to 150℃ and maintained at a stable temperature; S3: Acetylene and diethylene glycol are continuously introduced and reacted at a reaction pressure of 0.6 MPa to obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged. S4: The liquid produced in step S3 is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3; the vacuum degree of vacuum distillation is -0.095 MPa; S5: Diethylene glycol monovinyl ether crude product is subjected to continuous vacuum distillation to obtain diethylene glycol monovinyl ether; Potassium tetraborate is prepared by the following process: (1) Add potassium hydroxide to deionized water to obtain a potassium hydroxide solution with a mass concentration of 40%, and place it in a dropping funnel; (2) Add boric acid and deionized water to the reaction vessel, heat to 60°C and stir at 250 rpm to obtain a boric acid solution with a mass concentration of 25%; (3) At a stirring speed of 500 rpm, potassium hydroxide solution and boric acid solution were mixed to obtain potassium tetraborate solution; (4) Heat the potassium tetraborate solution in a water bath at a heating rate of 3℃ / min until it reaches 90℃. Stop heating and let it cool naturally to room temperature. Let it stand at room temperature for 45 minutes. After a large amount of crystals precipitate, filter the solution using a Buchner funnel to separate the crystals from the mother liquor.

[0025] (5) Wash the crystals five times with ice-cold anhydrous ethanol, and dry the crystals in an oven at 60°C for 2 hours to obtain potassium tetraborate powder. The molar ratio of boric acid to potassium hydroxide is 4.5:1.

[0026] Comparative Example 1: Based on Example 1, without nitrogen purging, including the following steps: S1: Add a diethylene glycol solution containing potassium diethylene glycol to the high-pressure reactor and mix thoroughly; the amount of potassium diethylene glycol used is 5% of the mass of the diethylene glycol solution; S2: Heat to 150℃ and maintain a stable temperature; S3: Acetylene and diethylene glycol are continuously introduced and reacted at a reaction pressure of 0.6 MPa to obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged. S4: The liquid produced in step S3 is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3; the vacuum degree of vacuum distillation is -0.095 MPa; S5: Diethylene glycol monovinyl ether crude product is obtained by continuous vacuum distillation.

[0027] Comparative Example 2: Based on Example 1, the amount of potassium diethylene glycol was adjusted, including the following steps: S1: Add a diethylene glycol solution containing potassium diethylene glycol to the high-pressure reactor and mix thoroughly; the amount of potassium diethylene glycol used is 0.1% of the mass of the diethylene glycol solution; S2: After being purged with nitrogen four times, the temperature is raised to 150℃ and maintained at a stable temperature; S3: Acetylene and diethylene glycol are continuously introduced and reacted at a reaction pressure of 0.6 MPa to obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged. S4: The liquid produced in step S3 is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3; the vacuum degree of vacuum distillation is -0.095 MPa; S5: Diethylene glycol monovinyl ether crude product is obtained by continuous vacuum distillation.

[0028] Comparative Example 3: Based on Example 1, the vacuum level of vacuum distillation was adjusted, including the following steps: S1: Add a diethylene glycol solution containing potassium diethylene glycol to the high-pressure reactor and mix thoroughly; the amount of potassium diethylene glycol used is 5% of the mass of the diethylene glycol solution; S2: After being purged with nitrogen four times, the temperature is raised to 150℃ and maintained at a stable temperature; S3: Acetylene and diethylene glycol are continuously introduced and reacted at a reaction pressure of 0.6 MPa to obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged. S4: The liquid produced in step S3 is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3; the vacuum degree of vacuum distillation is -0.080 MPa; S5: Diethylene glycol monovinyl ether crude product is obtained by continuous vacuum distillation.

[0029] Comparative Example 4: Based on Example 4, the preparation process of potassium tetraborate was adjusted. The only difference from Example 4 is that the molar ratio of boric acid to potassium hydroxide is 2:1.

[0030] Comparative Example 5: Based on Example 4, potassium tetraborate was replaced with commercially available potassium tetraborate. The only difference from Example 4 was that: S1: a diethylene glycol solution containing the catalyst was added to a high-pressure reactor and thoroughly mixed; the amount of catalyst was 5% of the mass of the diethylene glycol solution; and the catalyst was commercially available potassium tetraborate.

[0031] Comparative Example 6: Based on Example 4, potassium tetraborate was replaced with boric acid and potassium hydroxide. The only difference from Example 4 is that: S1: a diethylene glycol solution containing the catalyst was added to a high-pressure reactor and thoroughly mixed; the amount of catalyst was 5% of the mass of the diethylene glycol solution; the catalyst was boric acid and potassium hydroxide, and the mass ratio of boric acid to potassium hydroxide was 4:1.

[0032] Experiment: The diethylene glycol monovinyl ethers prepared in Examples 1-6 and Comparative Examples 1-6 were tested for their properties and the results were recorded. The yield of diethylene glycol monovinyl ether was determined by gas chromatography with internal standard method, using n-dodecane as internal standard. A standard curve was established to quantitatively analyze the reaction products, and the theoretical yield was calculated based on the amount of diethylene glycol fed. The yield was finally determined by the ratio of the actual yield to the theoretical yield. Purity analysis was performed by gas chromatography with area normalization method, and the purity data was obtained by calculating the percentage of the target product peak area to the total peak area.

[0033]

[0034] Conclusion: As can be seen from the comparison of the data in the table, the yield and purity of diethylene glycol monovinyl ethers in Examples 1-6 are significantly higher than those in Comparative Examples 1-6; Comparative Examples 1-3 were based on Example 1, but with adjusted synthesis process parameters. The yields and purity were significantly lower than in Examples 1-3. Comparative Example 1 (without nitrogen purging): the yield and purity decreased significantly, demonstrating that nitrogen purging effectively removes oxygen and moisture from the system, preventing catalyst deactivation and side reactions. Comparative Example 2 (catalyst dosage was 0.1% of the diethylene glycol solution mass): the yield and purity decreased significantly, indicating that a suitable catalyst concentration is crucial for ensuring reaction efficiency. Comparative Example 3 (reduced pressure distillation at -0.080 MPa): the yield and purity decreased significantly, demonstrating that reduced pressure distillation conditions (-0.090 to -0.099 MPa) have a significant impact on product separation and purification. Comparative Examples 4-6, based on Example 4, adjusted the catalyst formulation and preparation process, resulting in significantly lower yields and purities compared to Examples 4-6. Comparative Example 4 (with adjusted molar ratio of boric acid and potassium hydroxide): yield and purity were significantly lower than Example 4, demonstrating that precise control of the molar ratio of boric acid to potassium hydroxide is crucial in the synthesis of potassium tetraborate. When the molar ratio deviates from the preferred range of this invention, high-purity potassium tetraborate cannot be generated, potentially leading to the formation of more basic impurities such as potassium metaborate. These impurity catalysts are excessively basic, losing the mild basicity advantage unique to potassium tetraborate, and exacerbating the secondary reaction that leads to the continued reaction of the target product, monovinyl ether, to generate the byproduct, divinyl ether, thus resulting in decreased selectivity and yield. Comparative Example 5 (replacing potassium tetraborate with commercially available potassium tetraborate): yield and purity were significantly lower than Example 4, demonstrating the superior performance of the potassium tetraborate prepared by this invention. Commercially available potassium tetraborate typically contains multiple molecules of water of crystallization. The water released under reaction conditions can hydrolyze the generated vinyl ether products and may poison the basic active sites of the catalyst. This invention obtains low-moisture, high-activity potassium tetraborate powder through optimized preparation, anhydrous ethanol washing, and low-temperature drying processes, which is key to achieving high catalytic performance. Comparative Example 6 (potassium tetraborate replaced with boric acid and potassium hydroxide): the yield and purity are significantly lower than those of Example 4, proving the necessity of pre-synthesizing potassium tetraborate compounds as catalysts. Physically mixed boric acid and potassium hydroxide cannot immediately and completely form potassium tetraborate with a specific cyclic structure and moderate alkalinity in the reaction system, resulting in heterogeneity of the catalytic system and uncontrolled alkalinity. This not only reduces reaction efficiency, but the excessively strong local alkalinity can also promote the occurrence of side reactions. This invention directly uses pre-synthesized, structurally well-defined potassium tetraborate, which can provide a stable and suitable catalytic microenvironment, ensuring high selectivity and high conversion rate of the reaction. In summary, the diethylene glycol monovinyl ether synthesis process provided by this invention has significant advantages in terms of yield, product purity, and catalyst lifespan, and provides an effective technical solution to the problems of high energy consumption and serious pollution in existing processes.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A process for synthesizing diethylene glycol monovinyl ether, characterized in that: Includes the following steps: S1: Add the diethylene glycol solution containing the catalyst into the high-pressure reactor and mix thoroughly; S2: After nitrogen purging 3-5 times, the temperature is raised to the reaction temperature and maintained stable. S3: Acetylene and diethylene glycol are continuously introduced to react and obtain a diethylene glycol monovinyl ether solution, and the liquid is continuously discharged from the outlet. S4: The liquid produced in step S3 is subjected to vacuum distillation to obtain crude diethylene glycol monovinyl ether, while the catalyst is recovered and recycled for step S3. S5: Diethylene glycol monovinyl ether crude product is obtained by continuous vacuum distillation.

2. The synthesis process of diethylene glycol monovinyl ether according to claim 1, characterized in that: In step S1, the catalyst is potassium diethylene glycol.

3. The synthesis process of diethylene glycol monovinyl ether according to claim 1, characterized in that: In step S1, the amount of catalyst used is 0.5-10% of the mass of the diethylene glycol solution.

4. The synthesis process of diethylene glycol monovinyl ether according to claim 1, characterized in that: In step S2, the reaction temperature is 125~160℃.

5. The synthesis process of diethylene glycol monovinyl ether according to claim 1, characterized in that: In step S3, the reaction pressure is 0.2~1.0 MPa.

6. The synthesis process of diethylene glycol monovinyl ether according to claim 1, characterized in that: In step S4, the vacuum degree of the reduced pressure distillation is -0.090 to -0.099 MPa.

7. The synthesis process of diethylene glycol monovinyl ether according to claim 1, characterized in that: In step S1, the catalyst contains potassium tetraborate, which is obtained by the following process: (1) Add potassium hydroxide to deionized water to obtain a potassium hydroxide solution with a mass concentration of 30-40%, and place it in a dropping funnel; (2) Add boric acid and deionized water to the reaction vessel, heat to 60~80℃ and stir to obtain a boric acid solution with a mass concentration of 15~25%; (3) Mix potassium hydroxide solution and boric acid solution at a stirring speed of 300~500 rpm to obtain potassium tetraborate solution; (4) Heat the potassium tetraborate solution in a water bath at a heating rate of 1~3℃ / min to 80~90℃, stop heating, let it cool naturally to room temperature, let it stand at room temperature for 30~60min, and after a large amount of crystals precipitate, filter it with a Buchner funnel to separate the crystals from the mother liquor. (5) Wash the crystals 3 to 5 times with ice-cold anhydrous ethanol, and dry them to obtain potassium tetraborate powder.

8. The synthesis process of diethylene glycol monovinyl ether according to claim 7, characterized in that: The molar ratio of boric acid to potassium hydroxide is (4~4.5):

1.

9. The synthesis process of diethylene glycol monovinyl ether according to claim 7, characterized in that: The amount of potassium tetraborate added is 0-100% of the catalyst mass.

10. The synthesis process of diethylene glycol monovinyl ether according to claim 7, characterized in that: In step (5), the drying process conditions are: temperature 50~60℃, time 2~4h.

Images