A method for transesterification to produce n-decyl methacrylate

Abstract

A method for producing n-decyl methacrylate by transesterification. Methyl methacrylate, n-decanol, the polymerization inhibitor tetramethylpiperidine nitroxide phosphite, and a composite catalyst are added to an esterification reactor. The esterification reactor is heated by electricity and the temperature is raised to 106 °C - 109 °C for reaction for 5 h - 7 h. Then, the heating is stopped, and the reflux ratio of the reflux device at the top of the esterification reactor is controlled so that the temperature inside the esterification reactor is 125 - 137 °C and the temperature at the top of the rectifying column of the esterification reactor is 94 - 98 °C. The esterification reaction ends, and it is cooled by water to below 40 °C to obtain the esterification reaction product. It is filtered to remove the catalyst residue, and then subjected to vacuum rectification. After recovering methyl methacrylate and n-decanol, it is subjected to vacuum rectification to obtain n-decyl methacrylate. The advantages are: the process is simple and reasonable, the catalytic effect is good, and the composite catalyst containing an organic calcium catalyst is not easily decomposed, the product has good storage stability, high purity, and small chromaticity, meeting the usage requirements of users.

Description

Technical Field

[0001] The present invention relates to a method for producing n-decyl methacrylate by transesterification. Background Art

[0002] N-decyl methacrylate is a highly active monomer containing unsaturated double bonds. Its double bond structure endows polymers with excellent properties such as weather resistance, chemical resistance, and water resistance, making it widely used in fields such as optical adhesives, inks, coatings, adhesives, and lubricant additives. However, due to the relatively long carbon chain and high boiling point of this molecule, the catalytic efficiency of organotin catalysts is low and the dosage is large during the production process, and it is difficult to separate from the system. Residue is generated during the rectification process, which not only reduces the product yield, but also causes secondary pollution during the incineration treatment of the residue; the trace water contained in the raw materials and the decomposition products of organocalcium catalysts at specific temperatures will dissolve into the product, causing the product to change color and the storage stability to decline, making it difficult to meet the application requirements of users.

[0003] With the development of science and technology and the improvement of environmental protection requirements, products not only need to meet the needs of the application field, but also put forward higher requirements for the raw materials used throughout the production process. For example, the raw materials are non-toxic and harmless, and the waste is easy to handle and does not produce secondary pollution. At present, the production of n-decyl methacrylate mainly uses the alcohol-acid method or the transesterification method for synthesis, and the catalysts used are all traditional transesterification catalysts, organotin catalysts, which have high catalytic activity. In CN1097742A, a complex catalyst of calcium acetylacetonate and dibutyltin oxide is used, and in CN105294434A, a complex catalyst of calcium acetylacetonate and organotin is used. Although both methods have relatively high alcohol conversion rates and good yields, due to the use of calcium acetylacetonate as a catalyst, when the temperature is higher than 110 °C, there is trace water or it will decompose into acetylacetone at a temperature higher than 160 °C and remain in the product, resulting in unstable product color and unqualified color during storage. In addition, the organotin catalyst of dibutyltin oxide used also affects the product color, and the tin content cannot meet the requirements of the application field. At the same time, the residue containing organotin catalysts needs to be incinerated, and the secondary pollution also limits its use. Therefore, replacing organotin catalysts during the transesterification production process and not producing secondary pollution have great practical significance for the production of n-decyl methacrylate.

[0004] Journal of Hunan University of Arts and Science Vol.20 No.4 Dec.2008 "Synthesis of Higher Aliphatic Alcohol Esters of Methacrylic Acid by Transesterification Reaction" uses a magnetic Mg-Al-HT catalyst to synthesize higher carbon alcohol esters, and the highest conversion rate of n-decanol is 82%; at the same time, there are also introductions abroad about using hydrotalcite or hydrotalcite-like (LDO / LDH) solid base catalysts, but the yields and purities are not ideal. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for transesterification to produce n-decyl methacrylate with high purity and low chromaticity, which has a simple and reasonable process, good catalytic effect, and the composite catalyst containing an organic calcium catalyst is not easily decomposed, and the product has good storage stability, meeting the use requirements of users.

[0006] The technical solution of the present invention is as follows:

[0007] A method for transesterification to produce n-decyl methacrylate, the specific steps are as follows:

[0008] (1) Esterification reaction: Methyl methacrylate, n-decanol, the inhibitor tetramethylpiperidine nitroxide phosphite and a composite catalyst are added to an esterification reactor. The composite catalyst is a mixture of calcium acetylacetonate and calcium oxide. Among them, the molar ratio of methyl methacrylate to n-decanol is (2.8 - 3.3):1, the addition amount of the inhibitor accounts for 0.1% - 0.3% of the mass of n-decanol, and the addition amount of the composite catalyst accounts for 0.22% - 0.35% of the mass of n-decanol; The esterification reactor is heated by electricity, and the temperature is raised to 106°C - 109°C and reacted for 5h - 7h, then the heating is stopped, and the reflux ratio of the reflux device at the top of the esterification reactor is controlled to be (10 - 20):2, so that the temperature in the esterification reactor is 125 - 137°C, and the temperature at the top of the rectifying column of the esterification reactor is 94 - 98°C. The esterification reaction is completed, and the esterification reactor is cooled by water to below 40°C to obtain the esterification reaction product;

[0009] (2) Filtration and vacuum rectification: The esterification reaction product is filtered to remove the catalyst residue, and the filtrate of the esterification reaction product is collected; The filtered filtrate of the esterification reaction product is subjected to vacuum rectification. After recovering methyl methacrylate and n-decanol in the filtrate of the esterification reaction product, vacuum rectification is carried out to obtain n-decyl methacrylate.

[0010] Further, the mass ratio of calcium acetylacetonate to calcium oxide in the composite catalyst is (6 - 10):1.

[0011] Further, the purity of the n-decyl methacrylate ≥ 99%.

[0012] Further, the platinum-cobalt chromaticity of the obtained n-decyl methacrylate ≤ 10, the acid value ≤ 0.002 mg / g KOH, and the water content ≤ 0.05%.

[0013] Further, when vacuum rectification is used to recover methyl methacrylate and n-decanol in the filtrate of the esterification reaction product, the vacuum degree is 10 KPa - 13 KPa, and the rectification temperature is 48 - 160°C.

[0014] Further, when vacuum rectification is used to obtain n-decyl methacrylate, the vacuum degree is controlled at 1 KPa - 3 KPa, and the rectification temperature is 160°C - 165°C.

[0015] Furthermore, the mass content of the n-decanol is ≥ 99.17%.

[0016] The beneficial effects of the present invention are as follows:

[0017] 1. By using the complex of methyl methacrylate, n-decanol, and the composite catalyst calcium acetylacetonate and calcium oxide, an efficient, green, safe, and environmentally friendly production process route is achieved; this process not only reduces the amount of catalyst used but also avoids the use of organotin catalysts, thereby reducing environmental pollution.

[0018] 2. The obtained n-decyl methacrylate product has a purity of over 99%, and key indicators such as platinum-cobalt color, acid value, and moisture content all meet or exceed industry standards, meeting the requirements of various fields for this product.

[0019] 3. During the esterification process, by first filtering and separating the catalyst and then recovering the excess methyl ester and the remaining n-decanol through vacuum distillation, efficient utilization of raw materials is achieved, while the product yield is increased and the color is reduced.

[0020] 4. The complex of the composite catalysts calcium acetylacetonate and calcium oxide not only does not corrode the equipment, but also when the raw material contains trace amounts of water, calcium oxide can absorb water to form calcium hydroxide, avoiding the hydrolysis of calcium acetylacetonate, thereby ensuring the product color. The product does not change color after six months of storage, and has good storage stability; at the same time, the acetylacetone decomposed from the catalyst calcium acetylacetonate reacts with calcium hydroxide to regenerate the calcium acetylacetonate catalyst, further improving the catalytic efficiency.

[0021] 5. The adopted inhibitor has high inhibition performance, and through process control during the entire reaction, the smooth progress of the esterification reaction and the distillation process is ensured, and the operation is simple.

[0022] 6. The residue in the distillation kettle is less, the product yield is high, and the calcium oxide generated after the residue in the kettle is incinerated can be recycled without generating secondary pollution.

[0023] 7. The present invention not only meets the requirements of n-decyl methacrylate in various fields but also realizes industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the gas chromatogram of n-decyl methacrylate of the present invention (corresponding to Example 1);

[0025] Figure 2 is the gas chromatogram of n-decyl methacrylate of the present invention (corresponding to Example 2);

[0026] Figure 3 is the gas chromatogram of n-decyl methacrylate of the present invention (corresponding to Example 3);

[0027] Figure 4 is the gas chromatogram of n-decyl methacrylate of the present invention (corresponding to Example 4);

[0028] Figure 5 is the gas chromatogram of n-decyl methacrylate of the present invention (corresponding to Comparative Example 1);

[0029] Figure 6 is the gas chromatogram of n-decyl methacrylate of the present invention (corresponding to Comparative Example 2);

[0030] Figure 7 is the gas chromatogram of n-decyl methacrylate of the present invention (corresponding to Comparative Example 3). Detailed implementation mode

[0031] Example 1

[0032] First step: Esterification reaction

[0033] Add 416 g of methyl methacrylate, 200 g of n-decanol, 0.20 g of inhibitor tetramethylpiperidine nitroxide phosphite, 0.4 g of catalyst calcium acetylacetonate and 0.04 g of calcium oxide into a 1 L four-necked flask equipped with an electrically heated oil bath with a circulating water coil and equipped with a stirrer, a thermocouple, a rectification column, a reflux ratio controller, a condenser, and a receiving flask at one time. The mass content of the raw material n-decanol analyzed by gas chromatography is 99.17%; start the stirrer to stir the materials in the four-necked flask evenly, heat and raise the temperature of the four-necked flask with the electrically heated oil bath. When the temperature rises to 109 °C, the reaction starts. After 7 hours of reaction, stop heating. By controlling the reflux ratio of the reflux ratio controller at the top of the four-necked flask to be (10-20):2, the temperature in the four-necked flask is 137 °C, and the temperature at the top of the rectification column of the four-necked flask is 98 °C. The esterification reaction ends; turn on the circulating water coil to cool the esterification reaction solution in the four-necked flask to 40 °C with circulating water, and use a Buchner funnel with filter paper to vacuum filter through a suction flask to obtain 401.5 g of esterification filtrate. Analyze that the content of n-decanol in the esterification filtrate is 0.01%, and the alcohol conversion rate is (200 - 401.5×0.01%)÷200×100% = 99.98%;

[0034] Second step: Vacuum rectification to recover methyl methacrylate and n-decanol

[0035] Transfer the esterification filtrate to the rectification device, turn on the vacuum system to control the vacuum degree to 10 KPa, and the temperature in the kettle of the rectification device is 48-160 °C to recover methyl methacrylate and n-decanol;

[0036] Third step: Vacuum rectification to collect n-decyl methacrylate

[0037] The temperature of the esterified filtrate after the methyl methacrylate and n-decyl alcohol were recovered was further raised, and the vacuum degree was controlled to be 1 KPa. The top temperature of the distillation device was 160-162°C. 280.5 g (theoretical 286 g) of n-decyl methacrylate was obtained in the fraction, and the yield was 98%. The gas chromatogram of n-decyl methacrylate is shown in Figure 1 As shown, the peak time is 13.352 minutes, the purity is 99.22% after gas chromatography analysis, the platinum cobalt color is 5, the acid value is 0.002mg / g KOH, and the water content is 0.019%. The platinum cobalt color of the product after 6 months of storage is 5.

[0038] Example 2

[0039] Step 1: Esterification

[0040] In a 1L four-necked flask equipped with an electric heating oil bath with a circulating water coil, and equipped with a stirrer, a thermocouple, a distillation column, a reflux ratio controller, a condenser, and a receiving bottle, 354 g of methyl methacrylate, 200 g of n-decyl alcohol, 0.6 g of tetramethylpiperidinium nitroxide free radical phosphite triester as an inhibitor, 0.6 g of calcium acetylacetonate as a catalyst, and 0.1 g of calcium oxide were added at once. The mass content of the raw material n-decyl alcohol was 99.17% according to gas chromatography analysis. The stirrer was turned on to stir the materials in the four-necked flask evenly. The four-necked flask was heated to 106°C with an electric heating oil bath to start the reaction. The reaction lasted for 2 hours. 5 hours, stop heating, control the reflux ratio of the reflux ratio controller at the top of the four-necked flask to (10-20):2, make the temperature in the four-necked flask to 125°C, and the temperature at the top of the distillation column of the four-necked flask to 94°C, and the esterification reaction is finished; open the circulating water coil to cool the esterification reaction liquid in the four-necked flask to 40°C through circulating water, use a Buchner funnel with filter paper to vacuum filter through a suction flask to obtain 416.7 grams of esterification filtrate, and analyze the esterification filtrate to find that the n-decanol content is 0.01%, and the alcohol conversion rate is (200-416.7×0.01%)÷200×100%=99.97%;

[0041] Step 2: Recovery of methyl methacrylate and n-decanol by vacuum distillation

[0042] The esterification filtrate is transferred to a distillation device, and the vacuum system is turned on to control the vacuum degree to 13 KPa. The temperature in the kettle of the distillation device is set at 68-160° C. to recover methyl methacrylate and n-decanol;

[0043] Step 3: Collecting n-decyl methacrylate by vacuum distillation

[0044] The temperature of the esterified filtrate after the methyl methacrylate and n-decyl alcohol were recovered was further raised, and the vacuum degree was controlled to be 3 KPa. The top temperature of the distillation device was 163-165°C. 280.5 g (theoretical 286 g) of n-decyl methacrylate was obtained in the fraction, and the yield was 98.07%. The gas chromatogram of n-decyl methacrylate is shown inFigure 2 As shown, the peak time is 13.308 minutes, the purity is 99.34% after gas chromatography analysis, the platinum cobalt color is 10, the acid value is 0.001 mg / g KOH, and the water content is 0.016%. The platinum cobalt color of the product after 6 months of storage is 10.

[0045] Example 3

[0046] Step 1: Esterification

[0047] In a 1L four-necked flask equipped with an electric heating oil bath with a circulating water coil, and equipped with a stirrer, a thermocouple, a distillation column, a reflux ratio controller, a condenser, and a receiving bottle, 380 grams of methyl methacrylate, 200 grams of n-decyl alcohol, 0.4 grams of tetramethylpiperidinium nitroxide free radical phosphite triester as a polymerization inhibitor, 0.5 grams of calcium acetylacetonate as a catalyst, and 0.06 grams of calcium oxide were added at once. The mass content of the raw material n-decyl alcohol was 99.17% by gas chromatography analysis. The stirrer was started to stir the materials in the four-necked flask evenly. The four-necked flask was heated to 108°C with an electric heating oil bath to start the reaction. The reaction lasted for 10 minutes. After 6 hours, the heating was stopped, and the reflux ratio of the reflux ratio controller at the top of the four-necked flask was controlled to be (10-20):2, so that the temperature in the four-necked flask was 130°C, and the temperature at the top of the distillation column of the four-necked flask was 96°C, and the esterification reaction was completed; the circulating water coil was opened to cool the esterification reaction liquid in the four-necked flask to 40°C through the circulating water, and the esterification filtrate was obtained by vacuum suction filtration through a suction flask with a Buchner funnel with filter paper, and the esterification filtrate was 406.8 grams. The n-decanol content of the esterification filtrate was analyzed to be 0.01%, and the alcohol conversion rate was (200-406.8×0.01%)÷200×100%=99.97%;

[0048] Step 2: Recovery of methyl methacrylate and n-decanol by vacuum distillation

[0049] The esterification filtrate is transferred to a distillation device, and the vacuum system is turned on to control the vacuum degree to 11 KPa. The temperature in the kettle of the distillation device is set at 62-150° C. to recover methyl methacrylate and n-decanol;

[0050] Step 3: Collecting n-decyl methacrylate by vacuum distillation

[0051] The temperature of the esterified filtrate after the methyl methacrylate and n-decyl alcohol were recovered was further raised, and the vacuum degree was controlled to be 3 KPa. The top temperature of the distillation device was 163-165°C. 281 g of n-decyl methacrylate was obtained in the fraction (theoretical 286 g), and the yield was 98.2%. The gas chromatogram of n-decyl methacrylate is shown in Figure 3 As shown, the peak time is 13.317 minutes. The purity is 99.17% after gas chromatography analysis, the platinum-cobalt color is 5, the acid value is 0.001 mg / g KOH, and the water content is 0.02%. The platinum-cobalt color of the product is 5 after 6 months of storage.

[0052] Example 4

[0053] Step 1: Esterification

[0054] In a 1L four-necked flask equipped with an electric heating oil bath with a circulating water coil, and equipped with a stirrer, a thermocouple, a distillation column, a reflux ratio controller, a condenser, and a receiving bottle, 425 grams of recovered methyl methacrylate, 210 grams of n-decyl alcohol, 0.315 grams of tetramethylpiperidinium nitroxide free radical phosphite triester as a polymerization inhibitor, 0.42 grams of calcium acetylacetonate as a catalyst, and 0.06 grams of calcium oxide were added at once; the mass content of the raw material n-decyl alcohol was 99.17% by gas chromatography analysis; the stirrer was turned on to stir the materials in the four-necked flask evenly, and the four-necked flask was heated to 107°C with an electric heating oil bath to start the reaction, and the reaction After 6.5 hours, the heating was stopped, and the reflux ratio of the reflux ratio controller at the top of the four-necked flask was controlled to be (10-20):2, so that the temperature in the four-necked flask was 132°C, and the temperature at the top of the distillation column of the four-necked flask was 94°C, and the esterification reaction was completed; the circulating water coil was opened to cool the esterification reaction liquid in the four-necked flask to 40°C through the circulating water, and a Buchner funnel with filter paper was used to vacuum filter through a suction filter bottle to obtain 421.6 grams of esterification filtrate. The n-decanol content of the esterification filtrate was analyzed to be 0.01%, and the alcohol conversion rate was (210-421.6×0.01%)÷210×100%=99.98%;

[0055] Step 2: Recovery of methyl methacrylate and n-decanol by vacuum distillation

[0056] The esterification filtrate is transferred to a distillation device, and the vacuum system is turned on to control the vacuum degree to 12 KPa. The temperature in the kettle of the distillation device is 64-156°C to recover methyl methacrylate and n-decanol;

[0057] Step 3: Collect n-decyl methacrylate by vacuum distillation

[0058] The temperature of the esterified filtrate after the methyl methacrylate and n-decyl alcohol were recovered was further raised, and the vacuum degree was controlled to be 2.5 KPa. The top temperature of the distillation device was 164-165°C. 295.5 g of n-decyl methacrylate was obtained in the fraction (theoretical 300.31 g), and the yield was 98.39%. The gas chromatogram of n-decyl methacrylate is shown in Figure 4 As shown, the peak time is 13.318 minutes, the purity is 99.17% after gas chromatography analysis, the platinum-cobalt color is 5, the acid value is 0.001 mg / g KOH, and the water content is 0.018%. The platinum-cobalt color of the product after 6 months of storage is 5.

[0059] Example 5

[0060] Step 1: Esterification

[0061] In a 1L four-necked flask equipped with an electric heating oil bath pot with a circulating water coil and installed with a stirrer, a thermocouple, a distillation column, a reflux ratio controller, a condenser, and a receiving flask, 156 grams of recycled methyl methacrylate, 236 grams of commercially available methyl methacrylate, 200 grams of n-decanol, 0.5 grams of the polymerization inhibitor tetramethylpiperidine nitroxide phosphite, 0.54 grams of the catalyst calcium acetylacetonate, and 0.06 grams of calcium oxide were added at one time. The mass content of the raw material n-decanol analyzed by gas chromatography was 99.17%; the stirrer was started to stir the materials in the four-necked flask evenly, and the four-necked flask was heated and raised in temperature with the electric heating oil bath pot. When the temperature was raised to 106.5°C, the reaction started. After 6 hours of reaction, the heating was stopped. By controlling the reflux ratio of the reflux ratio controller at the top of the four-necked flask to be (10-20):2, the temperature in the four-necked flask was 129°C, and the temperature at the top of the distillation column of the four-necked flask was 96°C. The esterification reaction ended; the circulating water coil was opened to cool the esterification reaction solution in the four-necked flask to 40°C with circulating water, and vacuum filtration was carried out with a Buchner funnel with a filter cloth through a suction flask to obtain 408.8 grams of esterification filtrate. The n-decanol content in the esterification filtrate was analyzed to be 0.02%, and the alcohol conversion rate was (200 - 408.8×0.02%)÷200×100% = 99.95%;

[0062] Step 2: Vacuum distillation to recover methyl methacrylate and n-decanol

[0063] The esterification filtrate was transferred to the distillation device, and the vacuum system was opened to control the vacuum degree at 11 KPa. The temperature in the kettle of the distillation device was 54 - 158°C to recover methyl methacrylate and n-decanol;

[0064] Step 3: Vacuum distillation to collect n-decyl methacrylate

[0065] The esterification filtrate after recovering methyl methacrylate and n-decanol was continuously heated up, and the vacuum degree was controlled at 2 KPa. The temperature at the top of the distillation device was 163 - 165°C, and 281.7 grams (theoretical 286 grams) of n-decyl methacrylate were obtained as the distillate. The yield was 98.49%. After analysis by gas chromatography, the purity was 99.3%, the platinum-cobalt color number was 5, the acid value was 0.001 mg / g KOH, and the water content was 0.02%. The platinum-cobalt color number was retested after storing the product for 6 months and was 5.

[0066] Comparative Example 1

[0067] Step 1: Esterification reaction

[0068] In a 1L four-necked flask equipped with an electric heating oil bath pot with a circulating water coil, and equipped with a stirrer, a thermocouple, a distillation column, a reflux ratio controller, a condenser, and a receiving flask, 354 grams of methyl methacrylate, 200 grams of n-decanol, 0.6 grams of the inhibitor tetramethylpiperidine nitroxide phosphite, and 0.7 grams of the catalyst dibutyltin dilaurate were added at one time. The mass content of the raw material n-decanol analyzed by gas chromatography was 99.17%; the stirrer was started to stir the materials in the four-necked flask evenly, and the four-necked flask was heated and raised in temperature by the electric heating oil bath pot. When the temperature was raised to 109°C, the reaction started. After 10 hours of reaction, the heating was stopped. By controlling the reflux ratio of the reflux ratio controller at the top of the four-necked flask to be (10-20):2, the temperature in the four-necked flask was 125°C, and the temperature at the top of the distillation column of the four-necked flask was 98°C. The esterification reaction ended; the circulating water coil was opened to cool the esterification reaction solution in the four-necked flask to 40°C by circulating water, and vacuum filtration was carried out with a Buchner funnel with filter paper through a suction flask to obtain 393.7 grams of esterification filtrate. The n-decanol content in the esterification filtrate was analyzed to be 5.2%, and the alcohol conversion rate was (200 - 393.7×5.2%)÷200×100% = 89.77%;

[0069] Step 2: Vacuum distillation to recover methyl methacrylate and n-decanol

[0070] The esterification filtrate was transferred to the distillation device, and the vacuum system was opened to control the vacuum degree to 13 KPa. The temperature in the kettle of the distillation device was 68-160°C to recover methyl methacrylate and n-decanol;

[0071] Step 3: Vacuum distillation to collect n-decyl methacrylate

[0072] The esterification filtrate after recovering methyl methacrylate and n-decanol was continuously heated up, the vacuum degree was controlled to 3 KPa, the top temperature of the distillation device was 163-165°C, and 236.2 grams of n-decyl methacrylate were obtained from the distillate (179.5 grams of alcohol reacted, theoretically 256.7 grams), and the yield was 92.01%. The gas chromatogram of n-decyl methacrylate is as Figure 5 shown, the peak emergence time was 13.29 minutes, the purity analyzed by gas chromatography was 99.15%, the platinum-cobalt color number was 100, the product color was high, the acid value was 0.005 mg / g KOH, and the water content was 0.06%.

[0073] Comparative Example 2

[0074] Step 1: Esterification reaction

[0075] In a 1L four-necked flask equipped with an electric heating oil bath pot with a circulating water coil, and equipped with a stirrer, a thermocouple, a rectification column, a reflux ratio controller, a condenser, and a receiving flask, 354 grams of methyl methacrylate, 200 grams of n-decanol, 0.6 grams of the polymerization inhibitor tetramethylpiperidine nitroxide phosphite, and 0.7 grams of the catalyst calcium acetylacetonate were added at one time. The mass content of n-decanol analyzed by gas chromatography was 99.17%; the stirrer was started to stir the materials in the four-necked flask evenly, and the four-necked flask was heated and raised in temperature by the electric heating oil bath pot. When the temperature was raised to 108°C, the reaction started. After 8 hours of reaction, the heating was stopped. By controlling the reflux ratio of the reflux ratio controller at the top of the four-necked flask to be (10-20):2, the temperature in the four-necked flask was 127°C, and the temperature at the top of the rectification column of the four-necked flask was 94°C. The esterification reaction ended; the circulating water coil was opened to cool the esterification reaction solution in the four-necked flask to 40°C through circulating water, and vacuum filtration was carried out with a Buchner funnel with filter paper through a suction flask to obtain 405.8 grams of esterification filtrate. The content of n-decanol in the esterification filtrate was analyzed to be 0.8%, and the alcohol conversion rate was (200 - 405.8×0.8%)÷200×100% = 98.38%;

[0076] Step 2: Vacuum distillation to recover methyl methacrylate and n-decanol

[0077] The esterification filtrate was transferred to a distillation device, and the vacuum system was started to control the vacuum degree to 13 KPa. The temperature in the kettle of the distillation device was 68-160°C to recover methyl methacrylate and n-decanol;

[0078] Step 3: Vacuum distillation to collect n-decyl methacrylate

[0079] The esterification filtrate after recovering methyl methacrylate and n-decanol was continuously heated up, and the vacuum degree was controlled at 3 KPa. The top temperature of the distillation device was 163-165°C, and 267.5 grams (theoretical 281.3 grams) of n-decyl methacrylate were obtained from the distillate. The yield was 95.1%. The gas chromatogram of n-decyl methacrylate was as shown in Figure 6 shown, the peak emergence time was 13.292 minutes, the purity analyzed by gas chromatography was 99.17%, the platinum-cobalt color number was 30, the acid value was 0.002 mg / g KOH, and the water content was 0.08%. After standing for 7 days, the product turned yellow and the platinum-cobalt color number was greater than 100.

[0080] Comparative Example 3

[0081] Step 1: Esterification reaction

[0082] Add 354 g of methyl methacrylate, 200 g of n-decanol, 0.6 g of inhibitor tetramethylpiperidine nitroxide phosphite, 0.64 g of catalyst calcium acetylacetonate, and 0.06 g of dibutyltin oxide into a 1 L four-necked flask equipped with an electric heating oil bath pot with a circulating water coil, and installed with a stirrer, a thermocouple, a distillation column, a reflux ratio controller, a condenser, and a receiving flask at one time. The mass content of the raw material n-decanol analyzed by gas chromatography is 99.17%; start the stirrer to stir the materials in the four-necked flask evenly, heat and raise the temperature of the four-necked flask with the electric heating oil bath pot. When the temperature rises to 109 °C, the reaction starts. After 9 hours of reaction, stop heating. By controlling the reflux ratio of the reflux ratio controller at the top of the four-necked flask to be (10-20):2, the temperature in the four-necked flask is 126 °C, and the temperature at the top of the distillation column of the four-necked flask is 96 °C. The esterification reaction ends; turn on the circulating water coil to cool the esterification reaction solution in the four-necked flask to 40 °C with circulating water, and vacuum filter with a Buchner funnel with filter paper through a suction flask to obtain 408 g of esterification filtrate. Analyze that the n-decanol content in the esterification filtrate is 1.05%, and the alcohol conversion rate is (200 - 408×1.05%)÷200×100% = 97.86%;

[0083] Step 2: Vacuum distillation to recover methyl methacrylate and n-decanol

[0084] Transfer the esterification filtrate to the distillation device, turn on the vacuum system to control the vacuum degree to 13 KPa, and recover methyl methacrylate and n-decanol at the temperature in the kettle of the distillation device of 68-160 °C;

[0085] Step 3: Vacuum distillation to collect n-decyl methacrylate

[0086] Continue to raise the temperature of the esterification filtrate after recovering methyl methacrylate and n-decanol, control the vacuum degree to 3 KPa, the top temperature of the distillation device is 163-165 °C, and obtain 260.3 g (theoretical 279.8 g) of n-decyl methacrylate from the distillate. The yield is 93.03%. The gas chromatogram of n-decyl methacrylate is as Figure 7 shown, the peak emergence time is 13.305 minutes, the purity analyzed by gas chromatography is 99.15%, the platinum-cobalt chromaticity is 60, the acid value is 0.005 mg / g KOH, and the water content is 0.07%. After standing for 7 days, the material turns yellow and the platinum-cobalt chromaticity is greater than 100.

[0087] Comparative Example 4

[0088] Step 1: Esterification reaction

[0089] In a 1L four-necked flask equipped with an electric heating oil bath pot with a circulating water coil, and equipped with a stirrer, a thermocouple, a distillation column, a reflux ratio controller, a condenser, and a receiving flask, 354 grams of methyl methacrylate, 200 grams of n-decanol, 0.6 grams of the inhibitor tetramethylpiperidine nitroxide phosphite, and 0.7 grams of the catalyst calcium acetylacetonate were added at one time. The mass content of n-decanol analyzed by gas chromatography was 99.17%; the stirrer was started to stir the materials in the four-necked flask evenly, and the four-necked flask was heated and raised in temperature by the electric heating oil bath pot. When the temperature reached 108°C, the reaction started. After 8.5 hours of reaction, the heating was stopped. By controlling the reflux ratio of the reflux ratio controller at the top of the four-necked flask to be (10 - 20):2, the temperature in the four-necked flask was 128°C, and the temperature at the top of the distillation column of the four-necked flask was 96°C. The esterification reaction ended; the circulating water coil was opened to cool the esterification reaction liquid in the four-necked flask to 40°C by circulating water, and 403.2 grams of esterification filtrate was obtained without filtration. The content of n-decanol in the esterification filtrate was analyzed to be 0.56%, and the alcohol conversion rate was (200 - 403.2×0.56%)÷200×100% = 98.87%;

[0090] Step 2: Vacuum distillation to recover methyl methacrylate and n-decanol

[0091] The esterification filtrate was transferred to the distillation device, and the vacuum system was opened to control the vacuum degree at 13 KPa. The temperature in the kettle of the distillation device was 68 - 160°C to recover methyl methacrylate and n-decanol;

[0092] Step 3: Vacuum distillation to collect n-decyl methacrylate

[0093] The esterification filtrate after recovering methyl methacrylate and n-decanol was further heated up, and the vacuum degree was controlled at 3 KPa. The temperature at the top of the distillation device was 163 - 165°C, and 225.8 grams (theoretical 282.7 grams) of n-decyl methacrylate was obtained as the distillate. The yield was 79.87%. Analyzed by gas chromatography, the purity was 99.15%, the platinum-cobalt color number was 100, the acid value was 0.002 mg / g KOH, and the water content was 0.07%. After standing for 7 days, the color of the product was yellow, and it was out of range and could not be measured.

[0094] Compared with Comparative Example 1, in Comparative Example 4, the catalyst was not filtered and directly subjected to vacuum distillation, and the product yield was relatively low; because the catalyst was in the reaction liquid, after vacuum distillation, during the distillation process of the reaction liquid in the presence of the catalyst, part of it polymerized into oligomers and could not be distilled out, resulting in a decrease in yield. At the same time, the catalyst decomposed into acetylacetone and oxidized to change color, resulting in a darker color of the material. Further oxidation during storage made the material color darker, and the color stability of the product was poor.

[0095] The raw materials of this method are easily available. By adopting the method of controlling the whole process of cooling and filtering to remove the catalyst after esterification and then carrying out vacuum distillation, the whole esterification reaction and distillation separation process operations achieve an efficient, safe, stable and environmentally friendly production process. The use of the composite catalyst of calcium acetylacetonate and calcium oxide complex does not produce harmful substances, has no corrosion to equipment, and is safe, environmentally friendly and efficient.

[0096] It has great advantages in technology. The finally obtained product has high quality with a purity ≥ 99.17%, a platinum-cobalt color number ≤ 10, an acid value ≤ 0.002 mg / g KOH, and a moisture content ≤ 0.02%. The conversion rate is as high as 99.95%, and the yield is as high as over 98%. It can fully realize industrial production, and the product meets the requirements of various fields.

Claims

1. A method for producing n-decyl methacrylate by transesterification, characterized in that: Specific steps are as follows: (1) Esterification reaction: Methyl methacrylate, n-decanol, the inhibitor 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl phosphite triester, and a composite catalyst are added to an esterification reactor. The composite catalyst is a mixture of calcium acetylacetonate and calcium oxide. Among them, the molar ratio of methyl methacrylate to n-decanol is (2.8 - 3.3):

1. The addition amount of the inhibitor accounts for 0.1% - 0.3% of the mass of n-decanol, and the addition amount of the composite catalyst accounts for 0.22% - 0.35% of the mass of n-decanol. The esterification reactor is heated by electricity and the temperature is raised to 106°C - 109°C for reaction for 5h - 7h. Then, the heating is stopped, and the reflux ratio of the reflux device at the top of the esterification reactor is controlled to be (10 - 20):2, so that the temperature in the esterification reactor is 125 - 137°C, and the temperature at the top of the rectification device of the esterification reactor is 94 - 98°C. The esterification reaction ends, and the esterification reactor is cooled by water to below 40°C to obtain an esterification reaction product; (2) Filtration and vacuum rectification: The esterification reaction product is filtered to remove catalyst residues, and the filtrate of the esterification reaction product is collected. The filtered filtrate of the esterification reaction product is subjected to vacuum rectification. After recovering methyl methacrylate and n-decanol in the filtrate of the esterification reaction product, n-decyl methacrylate is obtained by vacuum rectification.

2. The method for producing n-decyl methacrylate by transesterification according to claim 1, characterized in that: The mass ratio of calcium acetylacetonate to calcium oxide in the composite catalyst is (6 - 10):

1.

3. The method for producing n-decyl methacrylate by transesterification according to claim 1, characterized in that: The purity of the obtained n-decyl methacrylate ≥ 99%.

4. The method for producing n-decyl methacrylate by transesterification according to claim 1, characterized in that: The platinum-cobalt color number of the obtained n-decyl methacrylate ≤ 10, the acid value ≤ 0.002 mg / g KOH, and the water content ≤ 0.05%.

5. The method for producing n-decyl methacrylate by transesterification according to claim 1, characterized in that: When recovering methyl methacrylate and n-decanol in the filtrate of the esterification reaction product by vacuum rectification, the vacuum degree is 10 KPa - 13 KPa, and the rectification temperature is 48 - 160°C.

6. The method for producing n-decyl methacrylate by transesterification according to claim 1, characterized in that: When obtaining n-decyl methacrylate by vacuum rectification, the vacuum degree is controlled at 1 KPa - 3 KPa, and the rectification temperature is 160°C - 165°C.

7. The method for producing n-decyl methacrylate by transesterification according to claim 1, characterized in that: The mass content of the n-decanol ≥ 99.17%.

Images