1-methylimidazole based on ionic liquid catalytic system and efficient synthesis process thereof

Abstract

The invention relates to the technical field of 1-methylimidazole and synthesis thereof, in particular to 1-methylimidazole based on an ionic liquid catalytic system and an efficient synthesis process of the 1-methylimidazole, glyoxal, methylamine and formaldehyde are used as raw materials, and the ionic liquid catalytic system is prepared by compounding sulfonic acid group and carboxyl functionalized ionic liquid according to the ratio of 2: 1. The cocatalyst is formed by compounding transition metal salt and organic alkali according to the ratio of 1: 2, the molar ratio of the raw materials is 1: 2: 2, and the sulfonyl ionic liquid is subjected to microwave activation, carboxyl ionic liquid loading, transition metal salt ultrasonic pretreatment and organic alkali rectification purification to synergistically promote the reaction, so that efficient synthesis of 1-methylimidazole is realized, and the yield and purity of the product are improved. According to the process, a specially treated ionic liquid catalytic system and a cocatalyst are adopted, operations such as pulse stirring and multiple extraction are combined, efficient synthesis of 1-methylimidazole is achieved, the product purity exceeds 99%, the yield exceeds 90%, the cost is reduced, pollution is reduced, the green chemistry concept is met, and the application prospect is wide.

Description

Technical Field

[0001] The present invention relates to the technical field of 1-methylimidazole and its synthesis, and specifically to a 1-methylimidazole and its efficient synthesis process based on an ionic liquid catalytic system. Background Art

[0002] As an important nitrogen-containing heterocyclic compound, 1-methylimidazole plays a key role in many fields such as medicine, chemical engineering, and materials. In the medical field, it is a key intermediate for the synthesis of various drugs, and many drug molecules with anti-inflammatory, anti-tumor, antibacterial and other biological activities contain 1-methylimidazole fragments in their structures. For example, some antifungal drugs bind to specific targets on the fungal cell membrane through the 1-methylimidazole structure, destroying the integrity of the cell membrane, thereby achieving the purpose of inhibiting fungal growth. In the chemical engineering field, 1-methylimidazole can be used to prepare high-performance solvents, ionic liquids, catalysts, etc. It can dissolve many organic and inorganic compounds and has good thermal stability and chemical stability, so it has broad application prospects in organic synthesis, catalytic reactions and other processes. In the materials field, 1-methylimidazole can be used to prepare polymer materials with special properties, such as conductive polymers, heat-resistant polymers, etc., providing new ideas and methods for the development of materials science.

[0003] At present, the synthesis methods of 1-methylimidazole mainly include traditional chemical synthesis methods and catalytic synthesis methods, etc. The traditional chemical synthesis method usually adopts multi-step reactions, using glyoxal, methylamine and formaldehyde as raw materials, and carrying out condensation, cyclization and other reactions under certain temperature and pressure conditions. However, this method has many drawbacks. The reaction steps are cumbersome and require multiple intermediate links, resulting in a long production cycle and high cost. At the same time, the reaction conditions are relatively harsh, requiring high temperature, high pressure and other conditions, with high requirements for equipment and large energy consumption. In addition, the selectivity of the traditional method is poor, there are many side reactions, and the product contains a large amount of impurities. Complicated separation and purification steps are required to obtain high-purity 1-methylimidazole, which not only increases the production cost but also reduces the production efficiency.

[0004] The catalytic synthesis method has improved the deficiencies of the traditional method to a certain extent. Some researchers have tried to use a single catalyst to promote the reaction, such as acid catalysts, base catalysts or metal catalysts, etc. Although these catalysts can improve the reaction rate and product yield to a certain extent, there are still some problems. The activity and selectivity of a single catalyst are limited, and it is difficult to achieve the efficient synthesis of 1-methylimidazole. The purity and yield of the product still need to be improved. Moreover, some catalysts are expensive, difficult to recycle, and easy to cause environmental pollution, restricting their large-scale industrial application.

[0005] As a new type of green solvent and catalyst, ionic liquids have unique physical and chemical properties, such as low vapor pressure, high solubility, good thermal stability, and designability. In recent years, the application of ionic liquids in the field of organic synthesis has received extensive attention. However, at present, the research on applying phase transfer catalysis technology to the synthesis of 1-methylimidazole is relatively less, and there are problems such as low catalyst activity and poor reaction selectivity in the existing ionic liquid catalytic synthesis process. Therefore, it is of great practical significance to develop a highly efficient, environmentally friendly process for the efficient synthesis of 1-methylimidazole. By optimizing the catalyst system and reaction conditions, improving the reaction selectivity and yield, and reducing production costs and environmental pollution, it will provide strong support for the large-scale production and wide application of 1-methylimidazole. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the present invention provides a 1-methylimidazole based on an ionic liquid catalytic system and its highly efficient synthesis process.

[0007] A 1-methylimidazole based on an ionic liquid catalytic system, using glyoxal, methylamine, and formaldehyde as starting materials, reacts under the combined action of an ionic liquid catalytic system and a co-catalyst. The main reaction formula is: , The ionic liquid catalytic system is composed of a sulfonic acid group-functionalized ionic liquid and a carboxyl group-functionalized ionic liquid compounded in a mass ratio of 2:1. The sulfonic acid group-functionalized ionic liquid is 1-(3-sulfopropyl)-3-methylimidazolium hydrogen sulfate. The sulfonic acid group in its molecular structure endows the ionic liquid with acidic catalytic activity, which can promote nucleophilic addition in the reaction. The carboxyl group-functionalized ionic liquid is 1-carboxymethyl-3-methylimidazolium tetrafluoroborate. The presence of the carboxyl group gives it certain polarity and special catalytic properties, which helps to stabilize and transform reaction intermediates. The co-catalyst is a transition metal salt and an organic base compounded in a mass ratio of 1:2. The transition metal salt is zinc chloride, and its central zinc ion can form a coordination bond with the reactants, changing the electron cloud distribution of the reactants, thereby reducing the reaction activation energy. The organic base is triethylamine, which has certain alkalinity, can adjust the pH value of the reaction system, and promote the shift of the reaction equilibrium. The molar ratio of the raw materials is glyoxal:methylamine:formaldehyde = 1:2:2. This ratio is determined through optimization experiments, which can make the reactants react fully and improve the production rate of the target product.

[0008] Preferably, the 1-(3-sulfopropyl)-3-methylimidazolium hydrogensulfate is treated by microwave activation. The microwave frequency is 2450 MHz, the power is 400 - 600 W, and the treatment time is 10 - 20 min. Under the action of the microwave field, the polar groups within the ionic liquid molecules will undergo rapid vibration and rotation, generating an internal heat effect, which causes a certain degree of change in the structure of the ionic liquid, enhancing its acidity. The activated ionic liquid can promote the condensation reaction of glyoxal and methylamine, and the intermediate reaction formula can be expressed as: , This condensation reaction is one of the key steps in the synthesis of 1-methylimidazole. The activated ionic liquid can increase the reaction rate and selectivity.

[0009] Preferably, the 1-carboxymethyl-3-methylimidazolium tetrafluoroborate is subjected to a loading treatment. Using mesoporous alumina as the carrier, mesoporous alumina has a high specific surface area, a uniform pore structure, and good thermal stability, which can provide a large number of loading sites for the ionic liquid. The ionic liquid is loaded on mesoporous alumina by the sol-gel method, and the loading amount is 15% - 25%. The specific operation is to first prepare mesoporous alumina sol, and then add the ionic liquid to the sol. Through processes such as gelation, drying, and calcination, the ionic liquid is evenly dispersed in the pores of mesoporous alumina. The loaded ionic liquid improves its dispersibility and stability in the reaction system, which is beneficial to promoting the subsequent cyclization reaction. The cyclization reaction formula can be expressed as: , The loading treatment can also prevent the ionic liquid from agglomerating and losing during the reaction process, and improve its reusability.

[0010] Preferably, the zinc chloride is pretreated by ultrasonic treatment. The ultrasonic frequency is 30 - 40 kHz, the power is 200 - 300 W, and the treatment time is 15 - 25 min. The ultrasonic action will generate a cavitation effect, forming tiny bubbles in the liquid. The rapid formation and rupture of the bubbles will produce local high temperature, high pressure, and strong shock waves, removing the impurities on the surface of the zinc chloride particles and exposing more active centers. After pretreatment, zinc chloride can catalyze the reaction synergistically with the ionic liquid, promoting the formation and transformation of imine intermediates. The imine formation reaction formula is: , where R, R’ represent the corresponding groups. This synergistic catalysis can further improve the reaction efficiency and product selectivity.

[0011] Preferably, the triethylamine is purified by rectification. Rectification is carried out at 89 - 90 °C. During the rectification process, by utilizing the difference in boiling points between triethylamine and other impurities, through multiple gas - liquid equilibriums, triethylamine is purified. The fraction is collected to obtain high - purity triethylamine with a purity of not less than 99%. High - purity triethylamine can more precisely adjust the acidity and alkalinity of the reaction system, avoid the interference of impurities on the reaction, promote the shift of the reaction equilibrium towards the direction of generating 1 - methylimidazole, thereby improving the product quality and yield.

[0012] Preferably, a high - efficiency synthesis process of 1 - methylimidazole based on an ionic liquid catalytic system comprises the following steps: S1, Add the microwave - activated 1 - sulfopropyl - 3 - methylimidazolium hydrogensulfate, the supported 1 - carboxymethyl - 3 - methylimidazolium tetrafluoroborate, the ultrasonically pretreated zinc chloride, and the rectification - purified triethylamine into a reaction kettle, and then add a certain amount of organic solvent. Toluene can be selected as the organic solvent. It has good solubility and chemical stability, and can fully dissolve and disperse the reactants and catalysts. Stir at a speed of 250 - 350 r / min for 20 - 40 min. The control of the stirring speed and time can ensure the uniform distribution of the catalyst and cocatalyst in the organic solvent, forming a stable reaction system; S2, According to the molar ratio of glyoxal:methylamine:formaldehyde = 1:2:2, add glyoxal, methylamine, and formaldehyde into the reaction kettle in sequence, heat up to 80 - 100 °C, and react under reflux for 3 - 5 h. A spherical condenser can be used as the reflux device, which can condense the volatile reactants and solvents back into the reaction kettle, improving the utilization rate of raw materials. During the reaction process, pulse - intermittent stirring is adopted, stirring for 15 min and then intermittent for 8 min. Pulse - intermittent stirring can make the reactants fully contact with the catalyst, avoid too high or too low local reactant concentration, improve the reaction rate, and at the same time prevent side reactions caused by local overheating; S3, After the reaction is completed, cool the reaction solution to room temperature, then carry out vacuum distillation to remove the organic solvent. Vacuum distillation can reduce the boiling point of the organic solvent and reduce the loss of the target product during the distillation process. Then add an appropriate amount of deionized water for washing. The number of washing times is 3 - 5 times. After each washing, liquid - liquid separation operation is carried out to obtain the organic phase. The washing process can remove the water - soluble impurities in the reaction solution and improve the purity of the organic phase; S4, Carry out extraction and separation on the organic phase, using ethyl acetate as the extractant, extract 3 - 5 times. Ethyl acetate has good extraction performance and can selectively extract the target product 1 - methylimidazole. After each extraction, the organic phases are combined to further enrich the target product; S5, Carry out vacuum rectification on the combined organic phase, and collect the fraction at 198 - 204 °C. Vacuum rectification can reduce the rectification temperature and avoid the decomposition of the target product at high temperatures. Collecting the fraction within this temperature range can obtain a high - purity 1 - methylimidazole product.

[0013] Preferably, the pulsed-intermittent stirring in S2 can make the reactants and the catalyst fully contact, improve the reaction rate, and at the same time avoid side reactions caused by local overheating. During the stirring process, the pulsed energy input enables the reactant molecules to continuously obtain kinetic energy, increasing the intermolecular collision frequency and the probability of effective collision, thereby accelerating the reaction. The intermittent operation gives the reaction system a certain buffer time, enabling the heat to be evenly distributed and preventing side reactions caused by too high local temperature.

[0014] Preferably, multiple extractions with ethyl acetate in S4 can more effectively separate the target product 1-methylimidazole and improve the product recovery rate. Multiple extractions can achieve a more sufficient distribution equilibrium of the target product between the organic phase and the aqueous phase, transfer more 1-methylimidazole from the aqueous phase to the organic phase. After each extraction, the organic phases are combined to further enrich the target product and reduce the loss of the target product, thereby improving the product recovery rate.

[0015] Preferably, the prepared 1-methylimidazole product has a purity of not less than 99% and a yield of not less than 90%, and has good chemical stability and selectivity. The high purity and high yield benefit from the optimized raw material ratio, the specially treated catalyst and cocatalyst, and the fine reaction and separation processes. The chemical stability of the product makes it not easily deteriorate during storage and subsequent applications, and the high selectivity ensures a low impurity content in the product, meeting the strict requirements for the raw material quality in the fields of medicine, chemical engineering, materials, etc.

[0016] Preferably, the 1-methylimidazole can be applied in the fields of medicine, chemical engineering, materials, etc.; in the medical field, it can be used as a drug intermediate for synthesizing drugs with anti-inflammatory, anti-tumor and other activities. Its special molecular structure can participate in the construction of various drug molecules, providing a basis for the activity and efficacy of the drugs; in the chemical engineering field, it can be used to prepare high-performance solvents, ionic liquids, etc., using its good solubility and chemical stability to improve the properties of solvents and ionic liquids; in the materials field, it can be used to prepare polymer materials with special properties, endowing the polymer materials with new properties by copolymerizing with other monomers.

[0017] Compared with the existing technologies, the beneficial effects of the present invention are: 1. In terms of the catalyst system, a mixture of sulfonic acid functionalized ionic liquid and carboxyl functionalized ionic liquid is used and subjected to special treatment. At the same time, a pretreated transition metal salt and a rectification-purified organic base are used as co-catalysts. Microwave activation enhances the acidity of the sulfonic acid functionalized ionic liquid, the loading treatment improves the dispersibility and stability of the carboxyl functionalized ionic liquid, ultrasonic pretreatment exposes more active centers of the transition metal salt, and rectification purification ensures the high purity of the organic base. These treatments enable the synergistic effect of the catalyst and co-catalyst, significantly improving the activity and selectivity of the reaction, laying the foundation for the efficient synthesis of 1-methylimidazole.

[0018] 2. The pulsed-intermittent stirring method allows the reactants to fully contact with the catalyst, avoiding local overheating, reducing the occurrence of side reactions, and improving the reaction efficiency. The separation and purification method using multiple extractions with ethyl acetate and vacuum rectification can more effectively separate the target product, greatly improving the recovery rate and purity of the product. The entire synthesis process is reasonably designed and all links are closely coordinated to ensure the smooth progress of the reaction.

[0019] 3. The 1-methylimidazole product prepared by this process has a purity of not less than 99% and a yield of not less than 90%. High purity and high yield mean excellent product quality, which can meet the needs of high-end fields such as medicine, chemical industry, and materials. At the same time, compared with traditional synthesis methods, the significant increase in yield reduces the production cost and improves the economic benefits.

[0020] 4. The ionic liquid used in this process has advantages such as low vapor pressure and recyclability, reducing the volatilization of organic solvents and the generation of waste. Moreover, the catalyst and co-catalyst can be recycled to a certain extent, further reducing environmental pollution, which is in line with the development concept of green chemistry. Description of the Drawings

[0021] Figure 1 is the production flow chart of the high-efficiency synthesis process of 1-methylimidazole based on the ionic liquid catalytic system; Figure 2 is the test result of the product purity and product yield in the examples and comparative examples. Detailed Embodiments

[0022] Example 1 Pretreatment of the catalyst and co-catalyst: Activation of the sulfonic acid functionalized ionic liquid: Place 1-sulfopropyl-3-methylimidazolium hydrogen sulfate in a microwave reactor, set the microwave frequency to 2450 MHz, the power to 400 W, and treat for 20 min. After treatment, the acidity of the ionic liquid is enhanced and the catalytic activity is improved; Carboxyl-functionalized ionic liquid loading: Using the sol-gel method, 1-carboxymethyl-3-methylimidazolium tetrafluoroborate was loaded onto mesoporous alumina, and the loading amount was controlled at 15%. During the preparation process, mesoporous alumina was first made into a sol, and then the ionic liquid was added and mixed thoroughly. The loading was completed through steps such as gelation, drying, and calcination; Ultrasonic pretreatment of zinc chloride: Zinc chloride was placed in an ultrasonic device. The ultrasonic frequency was set at 30 kHz, the power was 200 W, and the treatment time was 25 min. Ultrasonic treatment exposed more active centers of zinc chloride; Rectification and purification of triethylamine: Triethylamine was rectified, and the temperature was controlled at 89 - 90 °C. The fraction was collected to obtain triethylamine with a purity of not less than 99%.

[0023] Reaction system construction: In the reaction kettle, 1-sulfopropyl-3-methylimidazolium hydrogensulfate after microwave activation, loaded 1-carboxymethyl-3-methylimidazolium tetrafluoroborate, zinc chloride after ultrasonic pretreatment, and rectified and purified triethylamine were added in sequence. Then, an appropriate amount of toluene was added as an organic solvent. The stirrer was turned on and stirred at a speed of 250 r / min for 40 min to fully dissolve and disperse the catalyst and cocatalyst.

[0024] Reaction proceeding: According to the molar ratio of glyoxal:methylamine:formaldehyde = 1:2:2, glyoxal, methylamine, and formaldehyde were added to the reaction kettle in sequence. The reaction kettle was heated to 80 °C, and the reflux device (using a spherical condenser) was turned on. The reaction was carried out for 5 h. During the reaction process, pulse-intermittent stirring was used, with stirring for 15 min and intermittent for 8 min.

[0025] Post-treatment and separation and purification: After the reaction ended, the reaction solution was cooled to room temperature. Toluene was removed by vacuum distillation. An appropriate amount of deionized water was added to wash the organic phase 3 times. After each washing, liquid separation was carried out. The obtained organic phase was extracted 3 times with ethyl acetate. The organic phases were combined. Finally, the combined organic phase was subjected to vacuum rectification, and the fraction at 198 - 204 °C was collected to obtain a high-purity 1-methylimidazole product. After detection, the product purity was 99.1% and the yield was 90.5%.

[0026] Example 2 Pretreatment of catalyst and cocatalyst: The microwave power of sulfonic acid-functionalized ionic liquid was adjusted to 500 W and treated for 15 min; The loading amount of carboxyl-functionalized ionic liquid was increased to 20%; The ultrasonic frequency of zinc chloride was 35 kHz, the power was 250 W, and the treatment time was 20 min; The rectification operation of triethylamine was the same as that in Example 1.

[0027] Reaction system construction: Add the treated catalyst and promoter into the reactor, add toluene, and stir at 300 r / min for 30 min.

[0028] Reaction proceeds: Add raw materials in proportion, heat up to 90 °C, carry out reflux reaction for 4 h, and keep the pulse-intermittent stirring mode unchanged.

[0029] Post-treatment and separation and purification: Same operation steps as in Example 1. The purity of the final product is 99.3%, and the yield is 91.2%.

[0030] Example 3 Pretreatment of catalyst and promoter: The microwave power of sulfonic acid-functionalized ionic liquid is 600 W, and the treatment time is 10 min; The loading amount of carboxyl-functionalized ionic liquid reaches 25%; The ultrasonic frequency of zinc chloride is 40 kHz, the power is 300 W, and the treatment time is 15 min; The rectification operation of triethylamine is the same as before.

[0031] Reaction system construction: After adding each substance into the reactor and toluene, stir at 350 r / min for 20 min.

[0032] Reaction proceeds: Add raw materials, heat up to 100 °C, carry out reflux reaction for 3 h, and carry out pulse-intermittent stirring.

[0033] Post-treatment and separation and purification: Treat in the same way as in Example 1. The purity of the product is 99.5%, and the yield is 92.0%.

[0034] Comparative example Preparation of catalyst and promoter: Use the untreated 1-(3-sulfopropyl)-3-methylimidazolium hydrogensulfate and 1-carboxymethyl-3-methylimidazolium tetrafluoroborate mixed in a ratio of 2:1 as the ionic liquid catalyst, and ordinary zinc chloride and unrectified triethylamine in a ratio of 1:2 as the co-catalyst.

[0035] Reaction system construction: Add the above catalyst and promoter into the reactor, add toluene, and stir at 250 r / min for 30 min.

[0036] Reaction proceeds: Add raw materials in proportion, heat up to 90 °C, and continuously stir and react for 5 h.

[0037] Post-treatment and separation and purification: After the reaction was completed, the same post-treatment and separation and purification methods as in the examples were adopted. The purity of the finally obtained 1-methylimidazole product was 95.6%, and the yield was 82.3%.

[0038] From the above three examples and one comparative example, it can be seen that the catalyst and promoter pretreatment methods, pulse-intermittent stirring, and optimized separation and purification process adopted in this patent can significantly improve the product purity and yield of 1-methylimidazole, showing obvious advantages.

[0039] Comparison table of process conditions between examples and comparative example , Conclusion: It can be clearly seen from this table that there are significant differences in process conditions between the examples and the comparative example. In the examples, various pretreatments were carried out on the catalyst and promoter, and pulse-intermittent stirring was adopted, while in the comparative example, untreated raw materials and continuous stirring were used. These different process settings provide the basis for the subsequent differences in product quality and yield, indicating that the optimization of process conditions is crucial for the synthesis reaction.

[0040] Comparison table of product quality between examples and comparative example , Conclusion: Comparing the product quality data of the examples and the comparative example, it can be seen that the product purity of the examples is above 99%, and the yield is not less than 90%, while the purity of the comparative example is only 95.6% and the yield is 82.3%; this fully proves that the pretreatment method, pulse-intermittent stirring, and optimized separation and purification process adopted in this patent have a significant effect on improving the purity and yield of 1-methylimidazole, highlighting the advantages of this process.

[0041] Comparison table of performance of catalyst and promoter under different treatment methods , Conclusion: This table compares the performance of the catalyst and promoter after treatment in the examples and untreated in the comparative example. It can be found that after treatment, the performance of each catalyst and promoter has been significantly improved. The acidity and catalytic activity of the sulfonic acid-functionalized ionic liquid have been enhanced, the dispersion and stability of the carboxyl-functionalized ionic liquid have become better, the number of active centers of zinc chloride has increased, and the purity of triethylamine has been improved. These performance improvements provide guarantee for the efficient progress of the reaction and the improvement of product quality, further illustrating the importance of the pretreatment process.

[0042] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A 1-methylimidazole based on an ionic liquid catalyst system, characterized in that: Taking glyoxal, methylamine and formaldehyde as starting materials, the reaction is carried out under the joint action of ionic liquid catalytic system and co-catalyst, and the main reaction formula is: ， The ionic liquid catalytic system is compounded by a sulfonic acid functionalized ionic liquid and a carboxyl functionalized ionic liquid in a mass ratio of 2:1, wherein the sulfonic acid functionalized ionic liquid is 1-sulfonic acid propyl-3-methylimidazole hydrogen sulfate, and the carboxyl functionalized ionic liquid is 1-carboxymethyl-3-methylimidazole tetrafluoroborate; The co-catalyst is a transition metal salt and an organic base compounded in a mass ratio of 1:2, the transition metal salt is zinc chloride, the organic base is triethylamine, and the molar ratio of the raw materials is glyoxal:methylamine:formaldehyde=1:2:

2.

2. The 1-methylimidazole based on the ionic liquid catalyst system according to claim 1, characterized in that: The 1-sulfonic acid propyl-3-methyl imidazole hydrogen sulfate is subjected to microwave activation treatment, the microwave frequency is 2450 MHz, the power is 400-600 W, and the treatment time is 10-20 min; under the action of the microwave field, the polar groups in the ionic liquid molecules will vibrate and rotate rapidly, and the activated ionic liquid can promote the condensation reaction of glyoxal and methylamine, and the intermediate reaction formula can be expressed as: 。 3. The 1-methylimidazole based on the ionic liquid catalyst system according to claim 1, characterized in that: The 1-carboxymethyl-3-methylimidazolium tetrafluoroborate is subjected to a loading treatment, and the ionic liquid is loaded on the mesoporous alumina by a sol-gel method with mesoporous alumina as a carrier, and the loading amount is 15%-25%. A mesoporous alumina sol is first prepared, and then the ionic liquid is added to the sol. After gelation, drying and calcination, the ionic liquid is uniformly dispersed in the pores of the mesoporous alumina. The loaded ionic liquid improves the dispersibility and stability in the reaction system, which is conducive to promoting the subsequent cyclization reaction. The cyclization reaction formula can be expressed as: 。 4. The 1-methylimidazole based on the ionic liquid catalyst system according to claim 1, characterized in that: The zinc chloride is subjected to ultrasonic pretreatment, and the ultrasonic action will produce a cavitation effect, forming tiny bubbles in the liquid. The rapid formation and rupture of the bubbles will produce local high temperature, high pressure and strong shock waves, so that impurities on the surface of the zinc chloride particles are removed and more active centers are exposed. After pretreatment, the zinc chloride can synergistically catalyze the reaction with the ionic liquid to promote the formation and conversion of the imine intermediate. The imine formation reaction formula is: ， Wherein R, R' represent corresponding groups.

5. The 1-methylimidazole based on the ionic liquid catalyst system according to claim 1, characterized in that: The triethylamine is subjected to distillation purification treatment at 89-90° C. During the distillation process, the difference in boiling points between triethylamine and other impurities is utilized to purify the triethylamine through multiple gas-liquid equilibriums, and the fractions are collected to obtain high-purity triethylamine with a purity of not less than 99%.

6. An efficient synthesis process of 1-methylimidazole based on an ionic liquid catalyst system according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, adding microwave activated 1-sulfonic acid propyl-3-methyl imidazole hydrogen sulfate, supported 1-carboxymethyl-3-methyl imidazole tetrafluoroborate, ultrasonically pretreated zinc chloride and distilled purified triethylamine into a reaction kettle, and then adding a certain amount of organic solvent, wherein toluene is selected as the organic solvent, so that the reactants and the catalyst are fully dissolved and dispersed, and stirring at a speed of 250-350 r / min for 20-40 min. The control of stirring speed and time can ensure that the catalyst and the co-catalyst are evenly distributed in the organic solvent to form a stable reaction system; S2, according to the molar ratio of glyoxal: methylamine: formaldehyde = 1:2:2, glyoxal, methylamine and formaldehyde are added to the reactor in sequence, the temperature is raised to 80-100°C, and the reaction is carried out under reflux for 3-5 hours. The reflux device adopts a spherical condenser to condense the volatilized reactants and solvent and reflux them into the reactor. Pulse-intermittent stirring is adopted during the reaction process. The pulse-intermittent stirring can make the reactants fully contact with the catalyst and avoid excessively high or low concentration of the local reactants; S3, after the reaction is completed, the reaction solution is cooled to room temperature, and then the organic solvent is removed by vacuum distillation, and then an appropriate amount of deionized water is added for washing, the washing number is 3-5 times, and a liquid separation operation is performed after each washing to obtain an organic phase; S4, extracting and separating the organic phase, using ethyl acetate as an extractant, extracting 3-5 times, and combining the organic phases after each extraction to further enrich the target product; S5, subjecting the combined organic phase to vacuum distillation, collecting the fraction at 198-204° C., and obtaining a high-purity 1-methylimidazole product.

7. The efficient synthesis process of 1-methylimidazole based on an ionic liquid catalyst system according to claim 6, characterized in that: The pulse-intermittent stirring in S2 allows the reactants to fully contact the catalyst. During the stirring process, the pulsed energy input enables the reactant molecules to continuously gain kinetic energy, increasing the collision frequency and effective collision probability between molecules. The intermittent operation gives the reaction system a certain buffer time so that the heat can be evenly distributed.

8. The efficient synthesis process of 1-methylimidazole based on an ionic liquid catalyst system according to claim 6, characterized in that: In S4, ethyl acetate is used for multiple extractions to separate the target product 1-methylimidazole and improve the recovery rate of the product. Multiple extractions can achieve a more adequate distribution balance of the target product between the organic phase and the aqueous phase, and transfer more 1-methylimidazole from the aqueous phase to the organic phase. After each extraction, the organic phases are combined to further enrich the target product and reduce the loss of the target product.

9. The efficient synthesis process of 1-methylimidazole based on an ionic liquid catalyst system according to claim 6, characterized in that: The purity of the prepared 1-methylimidazole product is not less than 99%, and the yield is not less than 90%. The high purity and high yield are due to the optimized raw material ratio, specially treated catalysts and co-catalysts, and sophisticated reaction and separation processes.

10. An application of 1-methylimidazole prepared by the high-efficiency synthesis process of 1-methylimidazole based on an ionic liquid catalyst system according to claim 9, characterized in that: The 1-methylimidazole can be used in the fields of medicine, chemical industry, materials, etc. In the field of medicine, it can be used as a drug intermediate for synthesizing drugs with anti-inflammatory, anti-tumor and other activities; in the field of chemical industry, it can be used to prepare high-performance solvents and ionic liquids; in the field of materials, it can be used to prepare polymer materials with special properties.

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