A method for the continuous production of oxetane methacrylate by transesterification

Abstract

A method for continuously producing oxetane methyl methacrylate by transesterification, which utilizes dibutyl tin oxide, methyl methacrylate and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical to prepare a catalyst; methyl methacrylate is subjected to transesterification with 3-ethyl-3-oxetanemethanol, a polymerization inhibitor tetramethylpiperidine nitroxide phosphite triester and the catalyst to obtain a transesterification reaction liquid; the transesterification reaction liquid is subjected to vacuum rectification in a transesterification reactor, after recovering methyl methacrylate and 3-ethyl-3-oxetanemethanol, vacuum rectification is continued to obtain oxetane methyl methacrylate. The advantage is that the process is simple and reasonable, not only high in conversion rate and selectivity, but also high in purity, low in color and acid value of the obtained product, friendly to the environment and fully capable of meeting the application requirements in high-end fields.

Description

Technical Field

[0001] This invention relates to a method for the continuous production of oxetane methacrylate by transesterification. Background Technology

[0002] Oxetane methacrylate, as an important organic synthesis intermediate, possesses unique chemical structural advantages. The unsaturated double-bonded acrylate groups in its molecular structure endow it with high reactivity; while the oxetane monomer is suitable for two-step curing processes involving both photocuring and heat curing, and exhibits excellent weather resistance, chemical resistance, and water resistance. Based on these properties, oxetane methacrylate can participate in a variety of chemical reactions, playing a vital role in numerous fields such as organic synthesis and materials science. Compared to traditional methacrylate products containing unsaturated double bonds, it has a wider range of applications.

[0003] Currently, the production of methacrylate monomers mainly employs transesterification. However, oxetane methacrylates possess two functional groups—a C=C double bond and an epoxy bond—and have a small molecular weight and high reactivity, making them highly susceptible to polymerization during synthesis, thus hindering the acquisition of high-purity products. Traditional transesterification catalysts, such as organotin and organotitanium compounds, while meeting the production requirements for common methacrylate products containing only double bonds, suffer from low product purity and low yield for oxetane methacrylates that also contain a carbon-oxygen ring.

[0004] In China, there are currently no reports on the synthesis of high-purity oxetane methacrylate. Although Osaka Chemical (trade name OXE-30) in Japan has achieved the synthesis, sale, and use of this product, it still faces multiple technical barriers. CN104447635A discloses "an ester compound containing an oxetane group and its preparation method." This oxetane ester compound contains an oxetane similar to that of oxetane methacrylate. It uses an organotitanium catalyst, and after esterification, water is added to destroy the catalyst. The product is obtained through filtration, layering, concentration, and distillation, with a yield of up to 96%. However, this method has the following problems: no polymerization inhibitor is added during the reaction process to accelerate the polymerization reaction, but the product inevitably contains polymer impurities, affecting the purity of the product; even with concentration and distillation, it is difficult to obtain a high-purity product, which cannot meet the application requirements of high-end fields; in addition, adding water after esterification will destroy the secondary recycling of the catalyst, and the organic wastewater generated by filtration, layering, concentration, and distillation is difficult to treat. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for continuous production of oxetane methacrylate by transesterification, which not only has high conversion rate and selectivity, but also produces products with high purity, low color and low acid value, while being environmentally friendly and fully meeting the application needs of high-end fields.

[0006] The technical solution of this invention is:

[0007] A method for the continuous transesterification production of oxetane methacrylate comprises the following steps:

[0008] Step 1: Catalyst Preparation

[0009] Dibutyltin oxide, methyl methacrylate, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy radical were added to an ester exchange reactor. The molar ratio of dibutyltin oxide, methyl methacrylate, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy radical was 0.1:1.5:0.075. The ester exchange reaction was initiated at 102°C. After 5 hours of reaction, the temperature was increased to 130°C to terminate the reaction. The temperature was then lowered to 80°C, and methyl methacrylate was separated under reduced pressure to obtain a functional catalyst that acts as a polymerization inhibitor soluble in methyl methacrylate.

[0010] Step 2, transesterification reaction:

[0011] Methyl methacrylate, 3-ethyl-3-oxabutane methanol, tetramethylpiperidine nitroxide free radical phosphite, and the catalyst prepared in step one are added to an ester exchange reactor. The molar ratio of methyl methacrylate to 3-ethyl-3-oxabutane methanol is (2.1-3):1. The amount of the polymerization inhibitor added is 0.05% to 0.4% of the mass of 3-ethyl-3-oxabutane methanol, and the amount of the catalyst added is 1.0% to 4.2% of the mass of 3-ethyl-3-oxabutane methanol. The reaction is initiated by heating to 109℃ to 111℃. After 6 to 10 hours of reaction, heating is stopped. The temperature of the ester exchange reactor is raised to 130.6℃ to 140.6℃ by controlling the reflux ratio, and the top temperature of the distillation device of the ester exchange reactor is 94℃ to 96℃. The ester exchange reaction is then completed. The ester exchange reactor is cooled to below 40℃ using circulating cooling water to obtain the ester exchange reaction solution.

[0012] Step 3: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation:

[0013] The transesterification reaction solution was subjected to vacuum distillation in the transesterification reactor to recover methyl methacrylate and 3-ethyl-3-oxabutanol. After further vacuum distillation, oxabutan methacrylate was collected.

[0014] Furthermore, in step one, during the depressurization separation, the pressure is 0.4 kPa and the temperature is 80℃~150℃.

[0015] Furthermore, in step three, when recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation, the vacuum degree is controlled at 6.5 kPa to 9.5 kPa, and the temperature of the transesterification reactor distillation unit is 45°C to 115°C.

[0016] Furthermore, in step three, when collecting oxybutane methacrylate by vacuum distillation, the vacuum degree is controlled at 0.5 kPa to 2.5 kPa, and the top temperature of the transesterification reactor distillation unit is 115°C to 125°C.

[0017] Furthermore, the oxetane methacrylate has a platinum-cobalt color of ≤10, an acid value of ≤0.002 mg / g KOH, and a moisture content of ≤0.05%.

[0018] Furthermore, after collecting oxybutane methacrylate, the temperature of the transesterification reactor is lowered to below 90°C, and the catalyst is recovered for reuse.

[0019] Furthermore, the purity of the oxybutane methacrylate is ≥99%wt.

[0020] The beneficial effects of this invention are:

[0021] (1) The process is reasonable and has the characteristics of high production efficiency, fast speed, low pollution, continuity and excellent product performance; the amount of synthetic tin catalyst used is small and the selectivity is high. The alcohol content in the reaction solution is less than 0.52%wt, the alcoholization rate is more than 99%, and it does not corrode the equipment; the catalyst itself has a polymerization inhibition function combined with the polymerization inhibitor tetramethylpiperidine nitrogen oxide free radical phosphite, which can efficiently inhibit polymerization in the whole transesterification reaction process. The catalyst can also be reused many times, and it still has reaction activity after being reused 5 times.

[0022] (2) After the reaction is complete, excess methyl methacrylate and unreacted 3-ethyl-3-oxabutane methanol (methyl methacrylate recovery) can be recovered and collected for reuse as raw material. The waste catalyst is incinerated to produce tin oxide, which can be recycled and has minimal secondary pollution.

[0023] (3) The purity of the oxybutane methacrylate produced is ≥99%, the platinum-cobalt color is ≤10, the acid value is ≤0.002mg / g KOH, the moisture content is ≤0.05%, the alcohol conversion rate is ≥99%, and the yield is ≥97%, which can fully meet the application needs of high-end fields and can realize industrial continuous production. Attached Figure Description

[0024] Figure 1This is the gas chromatogram of oxetane methacrylate of the present invention (corresponding to Example 1);

[0025] Figure 2 This is the gas chromatogram of oxetane methacrylate of the present invention (corresponding to Example 2);

[0026] Figure 3 This is the gas chromatogram of oxetane methacrylate of the present invention (corresponding to Example 4);

[0027] Figure 4 This is the gas chromatogram of oxetane methacrylate of the present invention (corresponding to Example 7);

[0028] Figure 5 This is the gas chromatogram of oxetane methacrylate of the present invention (counterpart 1);

[0029] Figure 6 This is a gas chromatogram of oxetane methacrylate of the present invention (corresponding to example 2). Detailed Implementation

[0030] Example 1

[0031] Step 1: Catalyst Preparation

[0032] 24.9 g of dibutyltin oxide, 150 g of methyl methacrylate, and 12.92 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy free radical containing a hydroxyl polymerization inhibitor were added to a transesterification reactor. The temperature was raised to 102 °C and the transesterification reaction was started. Water was separated during the reaction. After 5 hours of transesterification reaction, the temperature was raised to 130 °C and the reaction was completed. The temperature was then lowered to 80 °C. Methyl methacrylate was separated under reduced pressure at a pressure of 0.4 kPa and a temperature of 80 °C to 150 °C to obtain 37 g of functional solid powder catalyst soluble in methyl methacrylate.

[0033] Step 2, transesterification reaction:

[0034] In a 1L transesterification reactor equipped with a stirrer, thermocouple, distillation apparatus, reflux ratio controller, condenser, receiving flask, and vacuum device, 600g of methyl methacrylate, 232.3g of 3-ethyl-3-oxabutane methanol, 0.47g of tetramethylpiperidine nitroxide radical phosphite (polymerization inhibitor), and 2.33g of the catalyst prepared in the first step were added in one step. The stirrer was started to mix the reactants evenly. The transesterification reactor was heated in an electrically heated oil bath until the temperature reached 109°C, at which point the reaction time was started. Methanol was separated by controlling the reflux ratio using a reflux ratio controller installed on the transesterification reactor. The temperature of the transesterification reactor reached 140.6℃, and the top temperature of the distillation unit installed on the transesterification reactor was 94℃. Heating was then stopped, and the reaction was allowed to proceed for 10 hours, at which point the transesterification reaction was complete. The circulating cooling water of the electrically heated oil bath was then turned on to cool the transesterification reaction solution to 40℃, yielding 550 grams of transesterification reaction solution. Analysis showed that the mass content of 3-ethyl-3-oxabutane methanol was 0.41%, and the alcohol conversion rate was 99.03%.

[0035] Step 3: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation.

[0036] The vacuum device was turned on to control the vacuum degree of the transesterification reactor to 9.5 kPa. The temperature inside the transesterification reactor was kept between 60℃ and 115℃ for vacuum distillation to recover methyl methacrylate and 3-ethyl-3-oxabutane methanol.

[0037] Step 4: Collect oxetane methacrylate by vacuum distillation.

[0038] After recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol from the transesterification reactor, the reaction solution was further heated and subjected to vacuum distillation. The vacuum was controlled at 2.5 kPa, and the top temperature of the distillation apparatus was maintained at 120℃–125℃. The distillate was collected, yielding 354 g of oxabutane methacrylate (theoretical yield 364.85 g), with a yield of 97.02%. The gas chromatogram of oxabutane methacrylate is shown below. Figure 1 As shown, the peak elution time was 10.858 minutes, the purity was 99.34%wt according to gas chromatography analysis, the platinum-cobalt color value was 5, the acid value was 0.001mg / g KOH, and the moisture content was 0.02%wt.

[0039] Example 2

[0040] Step 1, transesterification reaction:

[0041] In a 1L transesterification reactor equipped with a stirrer, thermocouple, distillation apparatus, reflux ratio controller, condenser, receiving flask, and vacuum device, 588g of methyl methacrylate, 325.3g of 3-ethyl-3-oxabutane methanol, 1.3g of the polymerization inhibitor tetramethylpiperidine nitric oxide triphosphite, and 9.75g of the catalyst prepared in Example 1 were added in one step. The stirrer was turned on to mix the reactants evenly. The transesterification reactor was heated in an electrically heated oil bath until the temperature reached 111°C, at which point the reaction time was started. The reflux ratio was controlled by the reflux ratio controller installed on the transesterification reactor to separate methanol. The temperature inside the transesterification reactor reached 130.6°C, and the top temperature of the distillation apparatus installed on the transesterification reactor was 96°C. Heating was stopped, and the reaction was allowed to proceed for 6 hours, at which point the transesterification reaction was complete. The circulating cooling water of the electrically heated oil bath was turned on to cool the transesterification reaction solution to 40°C, yielding 597g of transesterification reaction solution. Analysis showed that the mass content of 3-ethyl-3-oxabutane methanol was 0.38%, and the alcohol conversion rate was 99.3%.

[0042] Step 2: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation.

[0043] The vacuum device was turned on to control the vacuum degree of the transesterification reactor to 6.5 kPa. The temperature inside the transesterification reactor was kept between 45℃ and 110℃ for vacuum distillation to recover methyl methacrylate and 3-ethyl-3-oxabutane methanol.

[0044] Step 3: Collect oxetane methacrylate by vacuum distillation.

[0045] After recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol from the transesterification reactor, the reaction solution was further heated and subjected to vacuum distillation. The vacuum was controlled at 0.5 kPa, and the top temperature of the distillation column was maintained at 115℃–118℃. The distillate was collected, yielding 499.5 g of oxabutane methacrylate (theoretical yield 512.32 g), a yield of 97.5%. The gas chromatogram of oxabutane methacrylate is shown below. Figure 2 As shown, the peak elution time was 10.881 minutes. Gas chromatography analysis showed that the product purity was 99.20%wt, the platinum-cobalt color was 10, the acid value was 0.001 mg / g KOH, and the moisture content was 0.017%wt. After cooling to 90℃, 12.5 g of residue containing 9.75 g of catalyst was obtained. The residue was retained and reused as catalyst in multiple batches.

[0046] Example 3

[0047] Step 1, transesterification reaction:

[0048] In a 1L transesterification reactor equipped with a stirrer, thermocouple, distillation apparatus, reflux ratio controller, condenser, receiving flask, and vacuum device, 625g of methyl methacrylate, 290.4g of 3-ethyl-3-oxabutane methanol, 0.87g of tetramethylpiperidine nitric oxide triphosphite (an inhibitor of polymerization), and 5.8g of the catalyst prepared in Example 1 were added in one step. The stirrer was turned on to mix the reactants evenly. The transesterification reactor was heated in an electrically heated oil bath until the temperature reached 110°C, at which point the reaction time was started. The reflux ratio was controlled by the reflux ratio controller installed on the transesterification reactor to separate methanol. When the temperature inside the transesterification reactor reached 136°C and the top temperature of the distillation apparatus installed on the transesterification reactor reached 95°C, the heating was stopped. The transesterification reaction was completed after 8 hours. The circulating cooling water of the electrically heated oil bath was turned on to cool the transesterification reaction solution to 40°C, yielding 610g of transesterification reaction solution. The mass content of 3-ethyl-3-oxabutane methanol was analyzed to be 0.3%, and the alcohol conversion rate was 99.37%.

[0049] Step 2: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation.

[0050] The vacuum device was turned on to control the vacuum degree of the transesterification reactor to 8.5 kPa. The temperature inside the transesterification reactor was maintained between 70℃ and 113℃ for vacuum distillation to recover methyl methacrylate and 3-ethyl-3-oxabutane methanol.

[0051] Step 3: Collect oxetane methacrylate by vacuum distillation.

[0052] After recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol from the transesterification reactor, the transesterification reaction solution was further heated and subjected to vacuum distillation. The vacuum degree was controlled at 1.5 kPa, and the top temperature of the distillation unit was maintained at 118℃~123℃. The distillate was collected, yielding 444.8 g of oxabutane methacrylate (theoretical yield 457.67 g), with a yield of 97.18%. Gas chromatography analysis showed that the purity of oxabutane methacrylate was 99.08% wt, the platinum-cobalt color was 10, the acid value was 0.001 mg / g KOH, and the water content was 0.03% wt.

[0053] Example 4

[0054] Step 1, transesterification reaction:

[0055] In a 1L transesterification reactor equipped with a stirrer, thermocouple, distillation apparatus, reflux ratio controller, condenser, receiving flask, and vacuum device, 588g of methyl methacrylate, 325.3g of 3-ethyl-3-oxabutane methanol, 0.26g of the polymerization inhibitor tetramethylpiperidine nitroxide radical phosphite triester, and 12.5g of the reactor residue containing 9.75g of catalyst from Example 2 were added in one batch. The stirrer was turned on to mix the reactants evenly. The transesterification reactor was then heated to 110.5°C using an electrically heated oil bath. The timed reaction was started, and the reflux ratio was controlled by a reflux ratio controller installed on the transesterification reactor to separate methanol. The temperature inside the transesterification reactor reached 138°C, and the top temperature of the distillation unit installed on the transesterification reactor was 96°C. Heating was then stopped, and the transesterification reaction was completed after 8 hours. The circulating cooling water of the electrically heated oil bath was turned on to cool the transesterification reaction solution to 40°C, yielding 585 grams of transesterification reaction solution. Analysis showed that the mass content of 3-ethyl-3-oxabutane methanol was 0.51%, and the alcohol conversion rate was 99.08%.

[0056] Step 2: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation.

[0057] The vacuum device was turned on to control the vacuum degree of the transesterification reactor to 9 kPa, and the temperature inside the transesterification reactor was 72℃~114℃ for vacuum distillation to recover methyl methacrylate and 3-ethyl-3-oxabutane methanol.

[0058] Step 3: Collect oxetane methacrylate by vacuum distillation.

[0059] After recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol from the transesterification reactor, the reaction solution was further heated and subjected to vacuum distillation. The vacuum was controlled at 2 kPa, and the top temperature of the distillation apparatus was maintained between 119°C and 124°C. The distillate was collected, yielding 496.9 g of oxabutane methacrylate (theoretical yield 511.84 g), a yield of 97.2%. The gas chromatogram of oxabutane methacrylate is shown below. Figure 3 As shown, the peak elution time was 11.306 minutes. Gas chromatography analysis showed that the product purity was 99.16%wt, the platinum-cobalt color was 5, the acid value was 0.002 mg / g KOH, and the moisture content was 0.025%wt. After cooling to 90℃, 14.2 g of residue containing 9.75 g of catalyst was obtained. The residue was retained and reused as catalyst in the next batch.

[0060] Example 5

[0061] Step 1, transesterification reaction:

[0062] In a 1L transesterification reactor equipped with a stirrer, thermocouple, distillation apparatus, reflux ratio controller, condenser, receiving flask, and vacuum device, 600g of methyl methacrylate, 232.3g of 3-ethyl-3-oxabutane methanol, 0.12g of the polymerization inhibitor tetramethylpiperidine nitroxide radical phosphite, and 14.2g of the reactor residue containing 9.75g of catalyst from Example 4 were added in one step. The stirrer was started to ensure uniform mixing of the reactants. The transesterification reactor was then heated to 10°C using an electrically heated oil bath. The reaction was started at 9℃, and the reflux ratio was controlled by a reflux ratio controller installed on the transesterification reactor to separate methanol. The temperature inside the transesterification reactor reached 133℃, and the top temperature of the distillation device installed on the transesterification reactor was 94℃. Heating was then stopped, and the transesterification reaction was completed after 9 hours. The circulating cooling water of the electrically heated oil bath was turned on to cool the transesterification reaction solution to 40℃, yielding 430 grams of transesterification reaction solution. Analysis showed that the mass content of 3-ethyl-3-oxabutane methanol was 0.49%, and the alcohol conversion rate was 99.09%.

[0063] Step 2: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation.

[0064] The vacuum device was turned on to control the vacuum degree of the transesterification reactor to 9.5 kPa, and the temperature inside the transesterification reactor was 60℃~115℃ for vacuum distillation to recover methyl methacrylate and 3-ethyl-3-oxabutane methanol.

[0065] Step 3: Collect oxetane methacrylate by vacuum distillation.

[0066] After recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol from the transesterification reactor, the reaction solution was further heated and subjected to vacuum distillation. The vacuum degree was controlled at 2.5 kPa, and the top temperature of the distillation apparatus was maintained at 120℃~125℃. The distillate was collected, yielding 354.5 g of oxabutane methacrylate (theoretical yield 365.09 g), with a yield of 97.1%. Gas chromatography analysis showed that the purity of oxabutane methacrylate was 99.13% wt, the platinum-cobalt color was 5, the acid value was 0.001 mg / g KOH, and the water content was 0.016% wt. The solution was cooled to 90℃, yielding 15.2 g of residue containing 9.75 g of catalyst. This residue was retained and reused as catalyst in the next batch.

[0067] Example 6

[0068] Step 1, transesterification reaction:

[0069] In a 1L transesterification reactor equipped with a stirrer, thermocouple, distillation apparatus, reflux ratio controller, condenser, receiving flask, and vacuum device, 625g of methyl methacrylate, 290.4g of 3-ethyl-3-oxabutane methanol, 0.29g of the polymerization inhibitor tetramethylpiperidine nitroxide radical triphosphite, and 15.2g of the reactor residue containing 9.75g of catalyst from Example 5 were added in one step. The stirrer was started to ensure uniform mixing of the reactants. The transesterification reactor was then heated using an electrically heated oil bath until the internal temperature of the transesterification reactor reached [temperature missing]. The reaction was started at 111℃, and the reflux ratio was controlled by a reflux ratio controller installed on the transesterification reactor to separate methanol. The temperature inside the transesterification reactor reached 135℃, and the top temperature of the distillation apparatus installed on the transesterification reactor was 96℃. Heating was then stopped, and the reaction lasted for 7 hours, at which point the transesterification reaction was complete. The circulating cooling water in the electrically heated oil bath was turned on to cool the transesterification reaction solution to 40℃, yielding 635 grams of transesterification reaction solution. Analysis showed that the 3-ethyl-3-oxabutane methanol content was 0.41%, and the alcohol conversion rate was 99.1%.

[0070] Step 2: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation.

[0071] The vacuum device was turned on to control the vacuum degree of the transesterification reactor to 7 kPa, and the temperature inside the transesterification reactor was 48℃~111℃ for vacuum distillation to recover methyl methacrylate and 3-ethyl-3-oxabutane methanol.

[0072] Step 3: Collect oxetane methacrylate by vacuum distillation.

[0073] After recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol from the transesterification reactor, the reaction solution was further heated and subjected to vacuum distillation. The vacuum degree was controlled at 0.5 kPa, and the top temperature of the distillation apparatus was maintained at 115℃~118℃. The distillate was collected, yielding 443 g of oxabutane methacrylate (theoretical yield 456.45 g), with a yield of 97.05%. Gas chromatography analysis showed that the purity of oxabutane methacrylate was 99.12% wt, the platinum-cobalt color was 10, the acid value was 0.001 mg / g KOH, and the water content was 0.021% wt. The solution was cooled to 90℃, yielding 16 g of residue containing 9.75 g of catalyst. This residue was retained and reused as catalyst in the next batch.

[0074] Example 7

[0075] Step 1, transesterification reaction:

[0076] In a 1L transesterification reactor equipped with a stirrer, thermocouple, distillation apparatus, reflux ratio controller, condenser, receiving flask, and vacuum device, 540g of methyl methacrylate, 232.3g of 3-ethyl-3-oxabutane methanol, 0.35g of the polymerization inhibitor tetramethylpiperidine nitroxide radical triphosphite, and 16g of the reactor residue containing 9.75g of catalyst from Example 6 were added in one step. The stirrer was turned on to mix the reactants evenly. The transesterification reactor was then heated to 109°C using an electrically heated oil bath. The reaction was started at 8℃, and the reflux ratio was controlled by a reflux ratio controller installed on the transesterification reactor to separate methanol. The temperature inside the transesterification reactor reached 140℃, and the top temperature of the distillation apparatus installed on the transesterification reactor was 96℃. Heating was then stopped, and the reaction was completed after 10 hours. The circulating cooling water of the electrically heated oil bath was turned on to cool the transesterification reaction solution to 40℃, yielding 520 grams of transesterification reaction solution. Analysis showed that the mass content of 3-ethyl-3-oxabutane methanol was 0.43%, and the alcohol conversion rate was 99.03%.

[0077] Step 2: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation.

[0078] The vacuum device was turned on to control the vacuum degree of the transesterification reactor to 8 kPa, and the temperature inside the transesterification reactor was 49℃~113℃ for vacuum distillation to recover methyl methacrylate and 3-ethyl-3-oxabutane methanol.

[0079] Step 3: Collect oxetane methacrylate by vacuum distillation.

[0080] After recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol from the transesterification reactor, the reaction solution was further heated and subjected to vacuum distillation. The vacuum was controlled at 0.6 kPa, and the top temperature of the distillation apparatus was maintained between 118°C and 122°C. The fraction was retained, yielding 354.7 g of oxabutane methacrylate (theoretical yield 364.88 g), a yield of 97.2%. The gas chromatogram of oxabutane methacrylate is shown below. Figure 4 As shown, the peak elution time was 11.303 minutes, and the purity was 99.10%wt according to gas chromatography analysis. The platinum-cobalt color value was 10, the acid value was 0.001mg / g KOH, and the moisture content was 0.016%wt. After cooling to 90℃, 19g of residue containing 9.75g of catalyst was obtained.

[0081] Comparative Example 1

[0082] Step 1, transesterification reaction:

[0083] In a 1L transesterification reactor equipped with a stirrer, thermocouple, distillation apparatus, reflux ratio controller, condenser, receiving flask, and vacuum device, 588g of methyl methacrylate, 325.3g of 3-ethyl-3-oxabutane methanol, 1.3g of tetramethylpiperidine nitroxide free radical phosphite (polymerization inhibitor), and 9.75g of triisopropyl titanate were added in a single batch. The stirrer was started to ensure uniform mixing of the reactants. The transesterification reactor was then heated to 111°C using an electrically heated oil bath. The process was then initiated. The reaction was carried out over a period of time. The reflux ratio was controlled by a reflux ratio controller installed on the transesterification reactor to separate methanol. The temperature inside the transesterification reactor reached 140℃, and the top temperature of the distillation device installed on the transesterification reactor was 95℃. Heating was then stopped, and the reaction was completed after 11 hours. The circulating cooling water of the electrically heated oil bath was turned on to cool the transesterification reaction solution to 40℃, yielding 580 grams of transesterification reaction solution. Analysis showed that the 3-ethyl-3-oxabutane methanol content was 1.23%, and the alcohol conversion rate was 97.8%.

[0084] Step 2: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation.

[0085] The vacuum device was turned on to control the vacuum degree of the transesterification reactor to 6.5 kPa, and the temperature inside the transesterification reactor was 45℃~110℃ for vacuum distillation to recover methyl methacrylate and 3-ethyl-3-oxabutane methanol.

[0086] Step 3: Collect oxetane methacrylate by vacuum distillation.

[0087] After recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol from the transesterification reactor, the reaction solution was further heated and subjected to vacuum distillation. The vacuum was controlled at 0.5 kPa, and the top temperature of the distillation apparatus was maintained between 115°C and 118°C. The distillate was collected, yielding 428.9 g of oxabutane methacrylate (theoretical yield 504.6 g), with a yield of 85%. The gas chromatogram of oxabutane methacrylate is shown below. Figure 5 As shown, the peak elution time was 10.861 minutes. Gas chromatography analysis showed that the product purity was 98.97%wt, the platinum-cobalt color was 60, the acid value was 0.001 mg / g KOH, and the moisture content was 0.035%wt. The residue in the reactor was 85.7 grams, which adhered to the reactor wall and could not be used or dissolved, making it impossible to reuse the catalyst in the next batch.

[0088] Comparative Example 2

[0089] Step 1, transesterification reaction:

[0090] In a 1L transesterification reactor equipped with a stirrer, thermocouple, distillation apparatus, reflux ratio controller, condenser, receiving flask, and vacuum device, 588g of methyl methacrylate, 325.3g of 3-ethyl-3-oxabutane methanol, 1.3g of tetramethylpiperidine nitroxide triphosphite (polymerization inhibitor), and 9.75g of dibutyltin oxide were added in one step. The stirrer was started to mix the reactants evenly. The transesterification reactor was heated to 110°C using an electrically heated oil bath, and timing was started at this point. The reaction was carried out by separating methanol by controlling the reflux ratio using a reflux ratio controller installed on the transesterification reactor. The temperature inside the transesterification reactor reached 139.6℃, and the top temperature of the distillation device installed on the transesterification reactor was 96℃. Heating was then stopped, and the transesterification reaction was completed after 9 hours. The circulating cooling water of the electrically heated oil bath was turned on to cool the transesterification reaction solution to 40℃, yielding 600 grams of transesterification reaction solution. Analysis showed that the 3-ethyl-3-oxabutane methanol content was 0.8%, and the alcohol conversion rate was 98.52%.

[0091] Step 2: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation.

[0092] The vacuum device was turned on to control the vacuum degree of the transesterification reactor to 6.5 kPa. The temperature inside the transesterification reactor was 45℃~110℃ for vacuum distillation to recover methyl methacrylate and 3-ethyl-3-oxabutane methanol.

[0093] Step 3: Collect oxetane methacrylate by vacuum distillation.

[0094] After recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol from the transesterification reactor, the reaction solution was further heated and subjected to vacuum distillation. The vacuum was controlled at 0.5 kPa, and the top temperature of the distillation apparatus was maintained between 115°C and 118°C. The distillate was collected, yielding 381.3 g of oxabutane methacrylate (theoretical yield 508.3 g), a yield of 75%. The gas chromatogram of oxabutane methacrylate is shown below. Figure 6 As shown, the peak elution time was 11.132 minutes. Gas chromatography analysis showed that the product purity was 99.04%wt, the platinum-cobalt color was 50, the acid value was 0.001 mg / g KOH, and the water content was 0.038%wt. The residue of 130 g polymerized into a viscous liquid that could not be dissolved and could not be used for the next batch.

[0095] As can be seen from Example 2 and Comparative Examples 1 and 2, the process of Example 2 of the present invention has the advantages of high conversion rate, high yield, reusable catalyst residue, and low waste, and can realize continuous industrial production.

Claims

1. A method for the continuous transesterification production of oxetane methacrylate, characterized in that: The specific steps are as follows: Step 1: Catalyst Preparation Dibutyltin oxide, methyl methacrylate, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy radical were added to an ester exchange reactor. The molar ratio of dibutyltin oxide, methyl methacrylate, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy radical was 0.1:1.5:0.

075. The ester exchange reaction was initiated at 102°C. After 5 hours of reaction, the temperature was increased to 130°C to terminate the reaction. The temperature was then lowered to 80°C, and methyl methacrylate was separated under reduced pressure to obtain a functional catalyst that acts as a polymerization inhibitor soluble in methyl methacrylate. Step 2, transesterification reaction: Methyl methacrylate, 3-ethyl-3-oxabutane methanol, tetramethylpiperidine nitroxide free radical phosphite, and the catalyst prepared in step one are added to an ester exchange reactor. The molar ratio of methyl methacrylate to 3-ethyl-3-oxabutane methanol is (2.1-3):

1. The amount of the polymerization inhibitor added is 0.05% to 0.4% of the mass of 3-ethyl-3-oxabutane methanol, and the amount of the catalyst added is 1.0% to 4.2% of the mass of 3-ethyl-3-oxabutane methanol. The reaction is initiated by heating to 109℃ to 111℃. After 6 to 10 hours of reaction, heating is stopped. The temperature of the ester exchange reactor is raised to 130.6℃ to 140.6℃ by controlling the reflux ratio, and the top temperature of the distillation device of the ester exchange reactor is 94℃ to 96℃. The ester exchange reaction is then completed. The ester exchange reactor is cooled to below 40℃ using circulating cooling water to obtain the ester exchange reaction solution. Step 3: Recover methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation: The transesterification reaction solution was subjected to vacuum distillation in the transesterification reactor to recover methyl methacrylate and 3-ethyl-3-oxabutanol. After further vacuum distillation, oxabutan methacrylate was collected.

2. The transesterification continuous production method of oxetane methacrylate according to claim 1, characterized by: In step one, during the decompression separation, the pressure is 0.4 kPa and the temperature is 80℃~150℃.

3. The method for continuous transesterification production of oxetane methacrylate according to claim 1, characterized in that: In step three, when recovering methyl methacrylate and 3-ethyl-3-oxabutane methanol by vacuum distillation, the vacuum degree is controlled at 6.5 kPa to 9.5 kPa, and the temperature of the transesterification reactor distillation unit is 45°C to 115°C.

4. The method for continuous transesterification production of oxetane methacrylate according to claim 1, characterized in that: In step three, when collecting oxybutane methacrylate by vacuum distillation, the vacuum level is controlled at 0.5 kPa to 2.5 kPa, and the top temperature of the transesterification reactor distillation unit is 115°C to 125°C.

5. The method for continuous transesterification production of oxetane methacrylate according to claim 1, characterized in that: After collecting oxybutane methacrylate, the temperature of the transesterification reactor is lowered to below 90°C, and the catalyst is recovered for reuse.

Images