Method for preparing 2-methyl-2-acrylic acid-2-butoxyethyl ester by using aluminum isopropoxide as catalyst
By using an aluminum isopropoxide catalyst for transesterification and distillation, the problems of low purity and yellowing in the preparation of 2-methyl-2-acrylate-2-butoxyethyl ester were solved, and the preparation of high-purity products was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAANXI DAMEI CHEM TECH CO LTD
- Filing Date
- 2026-03-27
- Publication Date
- 2026-05-12
AI Technical Summary
The existing method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester produces byproducts, resulting in low product purity and a yellowish tinge after distillation.
2-Methyl-2-acrylate-2-butoxyethyl ester was prepared by transesterification using aluminum isopropoxide as a catalyst. The process included transesterification, solid-liquid separation, oil-water separation, and distillation, which reduced side reactions and improved product purity.
It achieves zero byproduct generation and a product purity of 99.5%, solving the problems of low purity and yellowing in existing technologies.
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Figure CN122010726A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical synthesis technology, specifically relating to a method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using aluminum isopropoxide as a catalyst. Background Technology
[0002] 2-Methyl-2-acrylate-2-butoxyethyl ester is a functional acrylate monomer that can be used to synthesize polymer materials, coatings, adhesives, etc., and has a wide range of applications in the field of organic synthesis.
[0003] Currently, the main method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester is a one-step process using methyl methacrylate (MMA) and ethylene glycol monobutyl ether as raw materials, a protic acid as a catalyst, and the addition of a solvent. This method generates byproducts, and the product obtained after distillation has low purity, resulting in a yellowish tint. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using aluminum isopropoxide as a catalyst. The method provided by this invention produces no byproducts and yields a product with high purity.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using aluminum isopropoxide as a catalyst, comprising: Methyl methacrylate, ethylene glycol monobutyl ether, aluminum isopropoxide and a polymerization inhibitor were mixed and subjected to transesterification to obtain the crude product. An organic solvent, an acid solution, and an alkali metal salt solution are added to the crude product, followed by solid-liquid separation to obtain a liquid phase. The liquid phase was subjected to oil-water separation, and the resulting oil phase was subjected to a first vacuum distillation to obtain crude 2-methyl-2-acrylic acid-2-butoxyethyl ester. The crude 2-methyl-2-acrylate-2-butoxyethyl ester was subjected to distillation to obtain 2-methyl-2-acrylate-2-butoxyethyl ester.
[0006] Preferably, the molar ratio of methyl methacrylate to ethylene glycol monobutyl ether is (3~5):1.
[0007] Preferably, the molar ratio of methyl methacrylate to aluminum isopropoxide is 4:(0.05~0.15).
[0008] Preferably, the temperature of the transesterification reaction is 90~100℃.
[0009] Preferably, the transesterification reaction takes 2 to 6 hours.
[0010] Preferably, the amount of the polymerization inhibitor is 0.01 to 0.02% of the mass of methyl methacrylate.
[0011] Preferably, the acid solution is hydrochloric acid or sulfuric acid.
[0012] Preferably, the vacuum degree of the first vacuum distillation is -0.09 to -0.1 MPa, and the temperature is 90 to 120°C.
[0013] Preferably, after the transesterification reaction is completed, the resulting system is subjected to a second vacuum distillation to obtain a crude product; the vacuum degree of the second vacuum distillation is -0.09 to -0.1 MPa, and the temperature is 90 to 120°C.
[0014] Preferably, the distillation is vacuum distillation; the vacuum degree of the vacuum distillation is -0.09 to -0.1 MPa, and the temperature is 110 to 130°C.
[0015] This invention provides a method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using aluminum isopropoxide as a catalyst, comprising: mixing methyl methacrylate, ethylene glycol monobutyl ether, aluminum isopropoxide, and a polymerization inhibitor, and then subjecting the mixture to a transesterification reaction to obtain a crude product; adding an organic solvent, an acid, and an alkali metal salt solution to the crude product, followed by solid-liquid separation to obtain a liquid phase; performing oil-water separation on the liquid phase, and subjecting the resulting oil phase to a first vacuum distillation to obtain crude 2-methyl-2-acrylate-2-butoxyethyl ester; and further distilling the crude 2-methyl-2-acrylate-2-butoxyethyl ester to fractional distillation to obtain 2-methyl-2-acrylate-2-butoxyethyl ester. This invention uses aluminum isopropoxide as the catalyst for the transesterification reaction, resulting in fewer side reactions and higher product purity. The results of the examples show that the product purity obtained by the method provided by this invention reaches 99.5%. Attached Figure Description
[0016] Figure 1 The chromatogram of crude 2-methyl-2-acrylate-2-butoxyethyl ester obtained in Example 1 of this invention; Figure 2 The chromatogram of crude 2-methyl-2-acrylate-2-butoxyethyl ester obtained in Example 2 of this invention; Figure 3 The chromatogram of crude 2-methyl-2-acrylate-2-butoxyethyl ester obtained in Example 3 of this invention; Figure 4 The chromatogram of crude 2-methyl-2-acrylate-2-butoxyethyl ester obtained in Comparative Example 1 of this invention; Figure 5 The chromatogram is of the crude 2-methyl-2-acrylic acid-2-butoxyethyl ester obtained in Comparative Example 2 of this invention. Detailed Implementation
[0017] All raw materials used in this invention are not particularly restricted in their source; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.
[0018] There are no particular restrictions on the purity of any of the raw materials used in this invention, but industrially pure raw materials are preferred.
[0019] This invention provides a method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using aluminum isopropoxide as a catalyst, comprising: Methyl methacrylate, ethylene glycol monobutyl ether, aluminum isopropoxide and a polymerization inhibitor were mixed and subjected to transesterification to obtain the crude product. An organic solvent, an acid solution, and an alkali metal salt solution are added to the crude product, followed by solid-liquid separation to obtain a liquid phase. The liquid phase was subjected to oil-water separation, and the resulting oil phase was subjected to a first vacuum distillation to obtain crude 2-methyl-2-acrylic acid-2-butoxyethyl ester. The crude 2-methyl-2-acrylate-2-butoxyethyl ester was subjected to distillation to obtain 2-methyl-2-acrylate-2-butoxyethyl ester.
[0020] In this invention, methyl methacrylate, ethylene glycol monobutyl ether, aluminum isopropoxide and a polymerization inhibitor are mixed and subjected to transesterification to obtain a crude product.
[0021] In this invention, the preferred molar ratio of MMA to ethylene glycol monobutyl ether is (3~5):1, more preferably 4:1. MMA and ethylene glycol monobutyl ether can undergo transesterification under the action of a catalyst, as shown in the following reaction formula: .
[0022] Excess MMA can promote the forward reaction and improve the conversion rate.
[0023] In this invention, the molar ratio of MMA to aluminum isopropoxide is preferably 4:(0.05~0.15), more preferably 4:0.1. Aluminum isopropoxide is a catalyst for the transesterification reaction of MMA and ethylene glycol monobutyl ether, which can reduce the occurrence of side reactions (such as self-polymerization of MMA); the amount of aluminum isopropoxide used within the above range is beneficial to improving the conversion rate of the transesterification reaction.
[0024] In this invention, the amount of the polymerization inhibitor is preferably 0.01~0.02% of the mass of MMA, more preferably 0.015%. Using the polymerization inhibitor within the above range is beneficial for reducing the self-polymerization of MMA.
[0025] In one embodiment of the present invention, the polymerization inhibitor may be p-hydroxyanisole.
[0026] In one embodiment of the present invention, the mixing can be done by adding the raw materials to a four-necked flask and stirring; the present invention does not have any particular requirements for the stirring rate, as long as the raw materials are stirred evenly.
[0027] In this invention, the temperature of the transesterification reaction is preferably 90-100°C, more preferably 95°C. A temperature within this range is beneficial for the transesterification reaction and further improves the yield.
[0028] In this invention, the transesterification reaction time is preferably 2-6 hours, more preferably 3-5 hours; as one embodiment of this invention, the transesterification reaction time can be 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours. A transesterification reaction time within the above range is beneficial for the transesterification reaction to proceed and further improves the yield.
[0029] In one embodiment of the present invention, the transesterification reaction can be carried out in a four-necked flask.
[0030] In this invention, after the transesterification reaction is completed, the resulting system is preferably subjected to a second vacuum distillation to obtain a crude product; the vacuum degree of the second vacuum distillation is preferably -0.09 to -0.1 MPa, more preferably -0.095 MPa; the temperature of the second vacuum distillation is preferably 90 to 120°C, more preferably 100 to 110°C. With the parameters of the second vacuum distillation within the above ranges, excess MMA and byproduct methanol can be removed.
[0031] In one embodiment of the present invention, the second vacuum distillation can be carried out until no fraction is distilled off; after the second vacuum distillation is completed, the four-necked flask can be placed in a 30°C water bath for cooling.
[0032] After obtaining the crude product, the present invention adds an organic solvent, an acid solution and an alkali metal salt solution to the crude product, and then performs solid-liquid separation to obtain a liquid phase.
[0033] In one embodiment of the present invention, the organic solvent may be toluene, and the amount of toluene may be 0.5 to 1 times the mass of MMA; toluene has excellent solubility and can dissolve oil-soluble substances in the reaction system.
[0034] In this invention, the acid solution is preferably hydrochloric acid or sulfuric acid, more preferably hydrochloric acid. Hydrochloric acid and sulfuric acid are both common acids that can react with aluminum isopropoxide to produce aluminum salts, aluminum hydroxide, and isopropanol, and they do not react with other substances in the reaction system, which is beneficial for product purification. As one embodiment of this invention, the mass concentration of the hydrochloric acid can be 37%, and the amount used can be 1 to 2 times the mass of the aluminum isopropoxide.
[0035] In one embodiment of the present invention, the alkali metal salt solution can be a saturated sodium chloride solution, and the amount of the saturated sodium chloride solution can be 0.3 to 1 times the mass of toluene. The present invention uses an alkali metal salt solution to dissolve water-soluble byproducts in the reaction system. The alkali metal salt solution has a good demulsification effect and is less prone to reaction, which is beneficial for further improving the purity of the product.
[0036] In one embodiment of the present invention, an organic solvent, an acid solution, and an alkali metal salt solution can be added sequentially to the crude product, and then the resulting mixture can be stirred for 1 hour.
[0037] In one embodiment of the present invention, the solid-liquid separation method can be filtration; the filtration material can be diatomaceous earth. Diatomaceous earth is a macroporous inorganic filter material with excellent particle adsorption properties, which can improve the retention effect of solids. In an embodiment of the present invention, the thickness of the diatomaceous earth is 2.2 cm.
[0038] The present invention does not impose any particular limitation on the filtration operation; solid-liquid separation can be achieved using conventional filtration methods in the art. The present invention removes aluminum hydroxide precipitate and other solid impurities generated from the reaction of aluminum isopropoxide with acid through filtration.
[0039] After obtaining the liquid phase, the present invention performs oil-water separation on the liquid phase, and performs a first vacuum distillation on the obtained oil phase to obtain crude 2-methyl-2-acrylic acid-2-butoxyethyl ester.
[0040] In one embodiment of the present invention, the oil-water separation method can be stirring followed by standing and separating the liquids; the stirring time can be 30 minutes, and the standing time can be 30 minutes; the present invention does not particularly limit the method of liquid separation, and conventional liquid separation methods in the art can be used to achieve oil-water separation.
[0041] In this invention, the vacuum degree of the first vacuum distillation is preferably -0.09 to -0.1 MPa, more preferably -0.095 MPa; the temperature of the first vacuum distillation is preferably 90 to 120°C, more preferably 100 to 110°C. In an embodiment of this invention, the temperature of the first vacuum distillation is 120°C. The boiling point of toluene is 110°C, the boiling point of isopropanol is 82.5°C, and the boiling point of 2-methyl-2-acrylate-2-butoxyethyl ester is 228°C. The first vacuum distillation can recover toluene and isopropanol and remove low-boiling-point byproducts and impurities, thereby improving the purity of 2-methyl-2-acrylate-2-butoxyethyl ester. The parameters of the first vacuum distillation being within the above ranges are beneficial for the removal of solvents, low-boiling-point byproducts and impurities, further improving the product purity.
[0042] After obtaining crude 2-methyl-2-acrylate-2-butoxyethyl ester, the present invention further distills the crude 2-methyl-2-acrylate-2-butoxyethyl ester to obtain 2-methyl-2-acrylate-2-butoxyethyl ester.
[0043] In this invention, the distillation is preferably vacuum distillation; the vacuum degree of the vacuum distillation is preferably -0.09 to -0.1 MPa, more preferably -0.095 MPa; the temperature of the vacuum distillation is preferably 110 to 130°C. Distillation can purify the product based on the difference in boiling points between the product and other substances (impurities, raw materials, etc.); distillation parameters within the above range are beneficial to improving product purity.
[0044] As one embodiment of the present invention, the distillation process can be as follows: crude 2-methyl-2-acrylic acid-2-butoxyethyl ester is added to a distillation apparatus, and the top temperature of the column is controlled at -0.095 MPa within the range of 110~130°C. The target main fraction is separated and collected by utilizing the difference in boiling points of the components, and finally a high-purity product is obtained.
[0045] This invention uses aluminum isopropoxide as a catalyst for transesterification, resulting in a short reaction time, few side reactions, and high product purity.
[0046] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0047] Example 1 A method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using aluminum isopropoxide as a catalyst comprises the following steps: MMA (100.12 g, 1 mol), ethylene glycol monobutyl ether (29.84 g, 0.25 mol), p-hydroxyanisole (0.02 g), and aluminum isopropoxide (5.11 g, 0.025 mol) are added to a 250 mL four-necked flask and stirred until homogeneous. The mixture is heated to 90 °C and reacted for 2 h. After the reaction is complete, a vacuum pump is started for a second reduced-pressure distillation (-0.095 MPa, 90 °C) until no distillate is obtained. The mixture is then cooled to 30 °C using a water bath. After the temperature of the system stabilizes, toluene (80 g), hydrochloric acid (37%, 8 g), and saturated chlorine are added sequentially to the flask. Sodium hydroxide solution (60g) was stirred for 1 hour and then filtered through diatomaceous earth (2.2cm thick). The filtrate was stirred and extracted in a flask, allowed to stand, and the lower aqueous phase was removed by separation, while the upper organic phase was collected. The organic phase was then subjected to a first vacuum distillation (-0.095MPa, 120℃) to obtain crude 2-methyl-2-acrylate-2-butoxyethyl ester (40.5g), with a yield of 87%. The crude 2-methyl-2-acrylate-2-butoxyethyl ester was added to a distillation apparatus, and the top temperature of the column was controlled at -0.095MPa within the range of 110~130℃. The target main fraction was separated and collected based on the difference in boiling points of the components, and finally, 2-methyl-2-acrylate-2-butoxyethyl ester product with a purity of 99.54% was obtained.
[0048] Example 2 A method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using aluminum isopropoxide as a catalyst comprises the following steps: MMA (100.12 g, 1 mol), ethylene glycol monobutyl ether (29.84 g, 0.25 mol), p-hydroxyanisole (0.02 g), and aluminum isopropoxide (2.55 g, 0.0125 mol) are added to a 250 mL four-necked flask and stirred until homogeneous. The mixture is heated to 90 °C and reacted for 6 h. After the reaction is complete, a vacuum pump is started for a second reduced-pressure distillation (-0.095 MPa, 90 °C) until no distillate is obtained. The mixture is then cooled to 30 °C using a water bath. After the temperature of the system stabilizes, toluene (80 g), hydrochloric acid (37%, 4 g), and saturated chlorine are added sequentially to the flask. Sodium hydroxide solution (40g) was stirred for 1 hour and then filtered through diatomaceous earth (2.2cm thick). The filtrate was extracted by stirring in a flask, allowed to stand, and the lower aqueous phase was removed by separation, while the upper organic phase was collected. The organic phase was then subjected to a first vacuum distillation (-0.095MPa, 120℃) to obtain crude 2-methyl-2-acrylate-2-butoxyethyl ester (29.2g), with a yield of 63%. The crude 2-methyl-2-acrylate-2-butoxyethyl ester was added to a distillation apparatus, and the top temperature of the column was controlled at -0.095MPa within the range of 110~130℃. The target main fraction was separated and collected by utilizing the difference in boiling points of the components, and finally, 2-methyl-2-acrylate-2-butoxyethyl ester product with a purity of 99.48% was obtained.
[0049] Example 3 A method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using aluminum isopropoxide as a catalyst, comprising the following steps: MMA (100.12 g, 1 mol), ethylene glycol monobutyl ether (29.84 g, 0.25 mol), p-hydroxyanisole (0.02 g), and aluminum isopropoxide (7.63 g, 0.0375 mol) are added to a 250 mL four-necked flask and stirred until homogeneous. The mixture is heated to 90 °C and reacted for 2 h. After the reaction is complete, a vacuum pump is started for a second reduced-pressure distillation (-0.095 MPa, 90 °C) until no distillate is obtained. The mixture is then cooled to 30 °C using a water bath. After the temperature of the system stabilizes, toluene (80 g), hydrochloric acid (37%, 12 g), and saturated... Sodium chloride solution (25g) was stirred for 1 hour and then filtered through diatomaceous earth (2.2cm thick). The filtrate was extracted by stirring in a flask, allowed to stand, and the lower aqueous phase was removed by separation, while the upper organic phase was collected. The organic phase was then subjected to a first vacuum distillation (-0.095MPa, 120℃) to obtain crude 2-methyl-2-acrylate-2-butoxyethyl ester (21.7g), with a yield of 47%. The crude 2-methyl-2-acrylate-2-butoxyethyl ester was added to a distillation apparatus, and the top temperature of the column was controlled at -0.095MPa within the range of 110~130℃. The target main fraction was collected by separating the components based on their boiling point differences, and finally, 2-methyl-2-acrylate-2-butoxyethyl ester product with a purity of 99.52% was obtained.
[0050] Comparative Example 1 A method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using tetrabutyl titanate as a catalyst, comprising the following steps: MMA (100.12 g, 1 mol), ethylene glycol monobutyl ether (29.84 g, 0.25 mol), p-hydroxyanisole (0.02 g), and tetrabutyl titanate (8.51 g, 0.025 mol) are added to a 250 mL four-necked flask and stirred until homogeneous. The mixture is heated to 90 °C and reacted for 6 h. After the reaction is complete, a vacuum pump is started to perform a second reduced-pressure distillation (-0.095 MPa, 90 °C) until no distillate is obtained. The mixture is then cooled to 30 °C using a water bath. After the temperature of the system stabilizes, toluene (80 g), hydrochloric acid (37%, 11 g), and saturated sodium hydroxide are added sequentially to the flask. Sodium chloride solution (60g) was stirred for 1 hour and then filtered through diatomaceous earth (2.2cm thick). The filtrate was extracted by stirring in a flask, allowed to stand, and the lower aqueous phase was removed by separation, while the upper organic phase was collected. The organic phase was then subjected to a first vacuum distillation (-0.095MPa, 120℃) to obtain crude 2-methyl-2-acrylate-2-butoxyethyl ester (27.9g), with a yield of 60%. The crude 2-methyl-2-acrylate-2-butoxyethyl ester was added to a distillation apparatus, and the top temperature of the column was controlled at -0.095MPa within the range of 110~130℃. The target main fraction was collected by separating the components based on their boiling point differences, and finally, 2-methyl-2-acrylate-2-butoxyethyl ester product with a purity of 97.54% was obtained.
[0051] Comparative Example 2 A method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using tetrabutyl titanate as a catalyst, comprising the following steps: MMA (100.12 g, 1 mol), ethylene glycol monobutyl ether (29.84 g, 0.25 mol), toluene (18.43 g), p-hydroxyanisole (0.02 g), and tetrabutyl titanate (8.51 g, 0.025 mol) are added to a 250 mL four-necked flask and stirred until homogeneous. The mixture is heated to 90 °C and reacted for 6 h. After the reaction is completed, a vacuum pump is started to perform a second reduced-pressure distillation (-0.095 MPa, 90 °C) until no distillate is obtained. The mixture is then cooled to 30 °C using a water bath. After the temperature of the system stabilizes, toluene (80 g) and hydrochloric acid (37%, 1% mol) are added sequentially to the flask. 1 g of saturated sodium chloride solution (60 g) was stirred for 1 h and then filtered through diatomaceous earth (2.2 cm thick). The filtrate was stirred and extracted in a flask, allowed to stand, and the lower aqueous phase was removed by separation, and the upper organic phase was collected. The organic phase was then subjected to a first vacuum distillation (-0.095 MPa, 120 °C) to obtain crude 2-methyl-2-acrylate-2-butoxyethyl ester (26.1 g), with a yield of 56%. The crude 2-methyl-2-acrylate-2-butoxyethyl ester was added to a distillation apparatus, and the top temperature of the column was controlled at -0.095 MPa within the range of 110~130 °C. The target main fraction was separated and collected by utilizing the difference in boiling points of the components, and finally 2-methyl-2-acrylate-2-butoxyethyl ester product was obtained with a purity of 97.46%.
[0052] Test Example 1 The crude 2-methyl-2-acrylic acid-2-butoxyethyl esters obtained in Examples 1-3 and Comparative Examples 1-2 were subjected to high-performance liquid chromatography (HPLC) for analysis, and the chromatograms are shown below. Figures 1-5 As shown, the chromatographic data are recorded in Table 1.
[0053] Table 1 Chromatographic data recording table for different products
[0054] from Figures 1-5 As can be seen from Table 1, there are no impurity peaks in Examples 1-3, indicating that aluminum isopropoxide has a good directional catalytic effect on the transesterification reaction; it also shows that different amounts of catalyst will affect the reaction rate. Within the same reaction time, the conversion rates of Examples 2-3 are all lower than those of Example 1.
[0055] Although Comparative Examples 1 and 2 produced less ethylene glycol monobutyl ether, they all generated a certain amount of impurities, which increased the difficulty of distillation and reduced the purity of the final product.
[0056] As can be seen from the above examples and comparative examples, the present invention uses aluminum isopropoxide as a catalyst for the transesterification reaction to prepare 2-methyl-2-acrylate-2-butoxyethyl ester, with fewer side reactions and higher product purity.
[0057] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing 2-methyl-2-acrylate-2-butoxyethyl ester using aluminum isopropoxide as a catalyst, comprising: Methyl methacrylate, ethylene glycol monobutyl ether, aluminum isopropoxide and a polymerization inhibitor were mixed and subjected to transesterification to obtain the crude product. An organic solvent, an acid solution, and an alkali metal salt solution are added to the crude product, followed by solid-liquid separation to obtain a liquid phase. The liquid phase was subjected to oil-water separation, and the resulting oil phase was subjected to a first vacuum distillation to obtain crude 2-methyl-2-acrylic acid-2-butoxyethyl ester. The crude 2-methyl-2-acrylate-2-butoxyethyl ester was subjected to distillation to obtain 2-methyl-2-acrylate-2-butoxyethyl ester.
2. The method according to claim 1, characterized in that, The molar ratio of methyl methacrylate to ethylene glycol monobutyl ether is (3~5):
1.
3. The method according to claim 1 or 2, characterized in that, The molar ratio of methyl methacrylate to aluminum isopropoxide is 4:(0.05~0.15).
4. The method according to claim 1, characterized in that, The temperature of the transesterification reaction is 90~100℃.
5. The method according to claim 1 or 4, characterized in that, The transesterification reaction takes 2 to 6 hours.
6. The method according to claim 1, characterized in that, The amount of the polymerization inhibitor is 0.01 to 0.02% of the mass of methyl methacrylate.
7. The method according to claim 1, characterized in that, The acid solution is hydrochloric acid or sulfuric acid.
8. The method according to claim 1, characterized in that, The vacuum degree of the first vacuum distillation is -0.09 to -0.1 MPa, and the temperature is 90 to 120 °C.
9. The method according to claim 1, characterized in that, After the transesterification reaction is completed, the resulting system is subjected to a second vacuum distillation to obtain the crude product; the vacuum degree of the second vacuum distillation is -0.09~-0.1MPa, and the temperature is 90~120℃.
10. The method according to claim 1, characterized in that, The distillation is a vacuum distillation; the vacuum degree of the vacuum distillation is -0.09 to -0.1 MPa, and the temperature is 110 to 130°C.