Synthesis process of bis (2, 2, 6, 6-tetramethyl-4-piperidyl) sebacate
Through solvent-free method and reflux device, the problems of high energy consumption, high wastewater and yellowing of the product in the preparation process of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate were solved, and a green synthesis process with low energy consumption, high quality and less waste liquid were achieved, with good product yield and performance.
Patent Information
- Application Number
- CN202510204035.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-24
- Publication Date
- 2025-06-06
AI Technical Summary
The existing preparation process of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate has problems such as high energy consumption, high wastewater, and easy yellowing of products, and the solvent-free method is difficult to implement and does not conform to the product quality in actual production.
Bis(2,2,6,6-tetramethyl-4-piperidyl)sebamate was synthesized by solvent-free method, by-product methanol was removed through a vacuum system, raw materials were prevented from sublimation using a reflux device, and color retention additives were added to prevent discoloration. Finally, residual raw materials were removed by negative pressure, and the water washing and crystallization steps were simplified.
A green synthesis process with low energy consumption, high quality and waste liquid has been achieved. The product yield can reach more than 99%, the color and light transmittance are good, and it meets the feasibility and quality requirements of industrial production.
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Figure CN120097900A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of chemical synthesis, in particular to a synthesis process of a hindered amine light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate. Background Art
[0002] Bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, also known as light stabilizer 770, is a representative hindered amine light stabilizer. It is widely used in various polymer materials and different application scenarios. It has good anti-light aging effect, and can be used in conjunction with ultraviolet absorbers and antioxidants to effectively extend the service life of polymer materials such as plastics and rubber.
[0003] At present, the common preparation method of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate in the industry is to synthesize it through transesterification reaction with tetramethylpiperidinol and dimethyl sebacate in a solvent atmosphere under the action of a catalyst, and then separate the methanol by reflux, separate the methanol and the solvent in a low-temperature separator to remove the methanol, so that the reaction proceeds in the forward direction. In addition, in the subsequent processing, the preparation of the finished product needs to be further completed through water washing, filtration, dehydration and decolorization, crystallization, drying and other processes.
[0004] Existing studies have found that when synthesizing bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate by transesterification, in addition to the target product bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate and a small amount of tetramethylpiperidinol, the reaction solution also contains a small amount of monoesterification products, as well as unilateral isopropanol esters or butanol transesterification intermediates produced by the catalyst. In addition, there are a small amount of amino compounds in the reaction solution. The amino compounds have two sources. One is that the raw material tetramethylpiperidinol contains trace amounts of tetramethylpiperidinamine and small molecular amines, and the other is amino chloride introduced by the catalyst. The presence of these amino substances will cause heating oxidation discoloration and rearrangement to conjugated structure discoloration, which will increase the chromaticity of the final product and turn the color yellow.
[0005] In addition, the existing preparation process has the problem that, due to the presence of solvents, the reflux methanol needs to be cooled with cold water for a long time, which consumes a lot of energy, and the tetramethylpiperidinol remaining in the reaction solution needs to be washed with a large amount of water, which produces a large amount of waste water, and a large amount of mother liquor is generated during the crystallization process, and the recovery and application procedures are complicated, resulting in multiple energy wastes. It does not meet the requirements of green manufacturing.
[0006] In addition, the existing report on solvent-free "CN 115819325 A method for synthesizing light stabilizer 770 using a solvent-free method" has two problems that cannot be implemented in actual production and do not meet product quality requirements. First, the raw material tetramethylpiperidinol sublimates severely during the synthesis process, resulting in an imbalance in the reaction ratio; second, due to the lack of solvent, the system is more susceptible to discoloration due to high-temperature oxidation during the reaction, which has no practical production significance.
[0007] Therefore, the industry is in urgent need of a preparation process that has low energy consumption, less waste liquid, is feasible and green and environmentally friendly, has practical production significance, and meets quality requirements. Summary of the invention
[0008] The purpose of the present invention is to provide a synthesis process of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate to solve the problems raised in the above background technology. 1) The process adopts a solvent-free synthesis method, and the by-product methanol is taken away by a vacuum system; 2) The sublimation of the raw material tetramethylpiperidinol is prevented by a reflux device, so that the reaction proceeds in the forward direction; 3) The product is prevented from yellowing by adding a color-preserving additive; 4) The residual raw material tetramethylpiperidinol is removed by negative pressure, the washing step is simplified, and the crystallization step is removed, so as to provide a low-energy, high-quality, and less waste liquid green synthesis process.
[0009] To achieve the above object, the present invention provides the following technical solutions: The present invention provides a method for preparing bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, comprising the following steps: Put tetramethyl piperidinol and dimethyl sebacate into a reactor equipped with a vacuum distillation device and a sublimation reflux device, add a catalyst and a color-preserving additive, turn on the sublimation reflux device, heat and stir under normal pressure to react; then turn on the vacuum system, react under reduced pressure, and distill out the by-product methanol; Close the sublimation reflux device and remove the residual tetramethylpiperidinol by vacuum distillation; Add hot water to the reaction solution obtained in step (2), stir, stand and separate the layers, then remove the lower layer of water. The obtained washing solution is dehydrated by distillation to obtain the bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate product.
[0010] Furthermore, the sublimation reflux device is any one of a reflux condenser, a rotary condenser, a fin condenser, a tube array, and a coil condenser.
[0011] Furthermore, in step (1), the molar ratio of tetramethyl piperidinol to dimethyl sebacate is 2-6:1; and the mass ratio of the catalyst, the color preservative, and tetramethyl piperidinol is 0.002-0.03:0.001-0.05:1.
[0012] Furthermore, in step (1), the catalyst is one or more of tetra-n-butyl titanate, tetra-isopropyl titanate, aluminum isopropoxide, sodium methoxide, lithium amide, and dibutyltin oxide.
[0013] Furthermore, in step (1), the color preserving additive is one or more of sodium borohydride, potassium borohydride, sodium triacetoxyborohydride, sodium sulfite, sodium bisulfite, sodium bisulphite, sodium dithionite, and hydrazine hydrate.
[0014] Furthermore, in step (1), the temperature is raised to 90-130° C. under normal pressure and stirred to carry out the reaction.
[0015] Furthermore, in step (1), the temperature of the sublimation reflux device is set to 110-160°C.
[0016] Furthermore, in step (1), the reduced pressure reaction temperature is 120-150° C., and the reduced pressure reaction pressure is -0.02 to -0.095 MPa.
[0017] Furthermore, in step (2), the temperature for removing the residual tetramethylpiperidinol by reduced pressure distillation is 120-160° C. and the pressure is -0.02 to -0.095 MPa.
[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts a solvent-free method to prepare bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, which eliminates the participation of solvents and reduces the waste of post-processing and copy-paste treatment; and by adding a reflux device, the sublimation of tetramethyl piperidine alcohol is prevented; and by adding a color retainer to ensure that the reaction system slows down discoloration, by-product methanol and residual tetramethyl piperidine alcohol are removed by reduced pressure distillation, the color retainer is removed by washing with a small amount of water, and the final product is obtained by distillation, dehydration, and granulation, and the product yield can reach more than 99%, and the chromaticity and light transmittance are good. The present invention avoids the high energy consumption of the reflux methanol of the traditional solvent method, and also avoids a large amount of waste water brought by multiple washings, and further removes the crystallization step, avoids the cumbersome procedures of copy-paste for producing a large amount of mother liquor, and ensures the stability of the product chromaticity during the synthesis process. The method reacts thoroughly, reduces unnecessary energy consumption and recycling steps, is easy to scale production, and has strong operability; energy consumption is reduced, costs are reduced, and production can be stably operated. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is the GC spectrum of the product in Example 1, bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate. DETAILED DESCRIPTION
[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1
[0021] In a 500ml four-necked flask equipped with a reflux condenser, add 330g of tetramethyl piperidine alcohol, 230g of dimethyl sebacate, 3g of tetrabutyl titanate, and 1g of sodium borohydride; control the internal temperature of the flask to 125°C, the temperature of the reflux condenser to 140°C (to recover tetramethyl piperidine alcohol and allow methanol to be distilled), stir and react for 2 hours, then turn on the vacuum pump, keep the reaction temperature unchanged, the pressure in the bottle -0.09Mpa, and continue to react for 4 hours. After the reaction is completed, turn off the reflux condenser for heating, and continue to maintain reduced pressure distillation at -0.09Mpa for 2h. Then add 80ml of hot deionized water to the reaction solution, keep it warm at 85°C, stir, stand for half an hour, and separate the lower layer of water. Finally, distill the residual water at 100°C at normal pressure to obtain the final product with a yield of 99%. After testing, the product GC content is 99.2%, the chromaticity is 4, and the transmittance at 425nm is 99.6%.
[0022] The GC preparation process data of the product bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate of Example 1 is shown in Table 1.
[0023] The GC spectrum report of the product bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate in Example 1 is shown in Figure 1 .Depend on Figure 1 It can be seen that at the 12.61min position, the product bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate gas phase peak appears, and its area percentage is 99.4%.
[0024] Table 1: Example 1 Bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate preparation process data step Product content Tetramethylol content Monoesters and impurities Light transmittance Chroma After normal pressure reaction 65.3% 11.4% 23.3% / / Decompression reaction ends 95.2% 3.1% 1.7% / / End of vacuum distillation 98.1% 0.2% 1.7% / / After washing 99.3% 0.1% 0.6% / / Final Product 99.2% 0.1% 0.7% 99.6% 4 Example 2
[0025] In a 1000ml four-necked flask equipped with a reflux condenser, add 425g of tetramethyl piperidine alcohol, 230g of dimethyl sebacate, and 6g of tetraisopropyl titanate. Divide the above mixture into two parts, A and B, and add 1.5g of sodium borohydride to A, and do not add sodium borohydride to B. Do a parallel experiment, control the internal temperature of the flask to 90°C, the temperature of the reflux condenser to 110°C, stir and react for 2 hours, then turn on the vacuum pump, maintain the reaction temperature at 125°C, the pressure in the bottle to -0.095Mpa, and continue to react for 4 hours. After the reaction is completed, turn off the reflux condenser heating, control the temperature in the bottle to 130°C, the negative pressure to -0.09Mpa, and the duration is 2h. Then add 100ml of hot deionized water to the reaction solution, keep it warm at 85°C, stir, stand for 1 hour, and separate the lower layer of water. Finally, the residual water was distilled off at 80°C under negative pressure to obtain the final products A and B. The yield of product A with the addition of sodium borohydride was 99%, the chromaticity was 3, and the transmittance at 425nm was 99.5%; the yield of product B without the addition of sodium borohydride was 99%, the chromaticity was 25, and the transmittance at 425nm was 97.3%, which were lower than the chromaticity and transmittance of the control group A and did not meet the high quality requirements of the product. Example 3
[0026] In a 1000ml four-necked flask equipped with a reflux condenser, add 450g of tetramethyl piperidine alcohol, 200g of dimethyl sebacate, 6g of tetrabutyl titanate, and 3g of sodium dithionite; control the internal temperature of the flask to 130°C, the temperature of the reflux condenser to 140°C, stir and react for 4 hours, then turn on the vacuum pump, maintain the reaction temperature at 155°C, the pressure in the bottle to -0.095Mpa, and continue to react for 4 hours. After the reaction is completed, turn off the reflux condenser for heating, control the temperature in the bottle to 145°C, the negative pressure to -0.095Mpa, and the duration is 2h. Then add 100ml of hot deionized water to the reaction solution, keep it warm at 90°C, stir, stand for 1 hour, and separate the lower layer of water. Finally, distill the residual water at 100°C at normal pressure to obtain the final product, with a product yield of 99%, a chromaticity of 3, and a 425nm transmittance of 99.6%. Example 4
[0027] In a 500ml four-necked flask equipped with a reflux condenser, add 250g of tetramethyl piperidine alcohol, 115g of dimethyl sebacate, 3g of tetraisopropyl titanate, and 3g of sodium dithionite; control the internal temperature of the flask to 125°C, the temperature of the reflux condenser to 130°C, stir and react for 1 hour, then turn on the vacuum pump, maintain the reaction temperature at 125°C, the pressure in the bottle to -0.09Mpa, and continue to react for 2 hours. After the reaction is completed, turn off the reflux condenser for heating, control the temperature in the bottle to 130°C, the negative pressure to -0.095Mpa, and the duration is 2h. Then add 80ml of hot deionized water to the reaction solution, keep it at 90°C, stir, stand for 1 hour, and separate the lower layer of water. Finally, distill the residual water at 100°C at normal pressure to obtain the final product, with a product yield of 99%, a chromaticity of 1, and a 425nm transmittance of 99.8%. Example 5
[0028] In the experiment of group C, 250g of tetramethyl piperidine alcohol, 115g of dimethyl sebacate, 3g of tetrabutyl titanate, and 3g of sodium borohydride were added to a 500ml four-necked flask equipped with a reflux condenser; the internal temperature of the flask was controlled at 130°C, the temperature of the reflux condenser was controlled at 140°C, the reaction was stirred for 1 hour, and then the vacuum pump was turned on to maintain the reaction temperature at 140°C, the pressure in the bottle was -0.09Mpa, and the reaction was continued for 2 hours. After the reaction was completed, the reflux condenser was turned off for heating, the temperature in the bottle was controlled at 150°C, the negative pressure was -0.095Mpa, and the duration was 2h. Then 80ml of hot deionized water was added to the reaction solution, kept at 90°C, stirred, and allowed to stand for 1 hour, and the lower layer of water was separated. Finally, the residual water was distilled off at 100°C at normal pressure to obtain the final product, with a product chromaticity of 1 and a transmittance of 99.8% at 425nm.
[0029] In the experiment of group D, 250g of tetramethyl piperidine alcohol, 115g of dimethyl sebacate, and 3g of tetrabutyl titanate were added to a 500ml four-necked flask equipped with a reflux condenser; the internal temperature of the flask was controlled at 130°C, the temperature of the reflux condenser was controlled at 140°C, the reaction was stirred for 1 hour, and then the vacuum pump was turned on to maintain the reaction temperature at 140°C, the pressure in the bottle was -0.09Mpa, and the reaction was continued for 2 hours. After the reaction was completed, the reflux condenser was turned off for heating, the temperature in the bottle was controlled at 150°C, the negative pressure was -0.095Mpa, and the duration was 2h. Then 80ml of hot deionized water and 3g of sodium borohydride were added to the reaction solution, the temperature was kept at 90°C, stirred, and allowed to stand for 1 hour, and the lower layer of water was separated. Finally, the residual water was distilled off at 100°C at normal pressure to obtain the final product, the product chromaticity was 20, and the transmittance at 425nm was 98.6%, which was lower than the chromaticity and transmittance of the control group C, and did not meet the high quality requirements of the product. By comparison, it was found that adding a color preservative during the reaction stage can better prevent oxidative discoloration.
[0030] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.
[0031] It should be noted that the above content only illustrates the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications all fall within the protection scope of the claims of the present invention.
Claims
1. A method for preparing bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, characterized in that: The following steps are involved: (1) tetramethylpiperidinol and dimethyl sebacate are placed in a reactor equipped with a vacuum distillation device and a sublimation reflux device, a catalyst and a color-preserving additive are added, the sublimation reflux device is turned on, the temperature is increased under normal pressure and stirred to react; then the vacuum system is turned on, the vacuum reaction is carried out, and the by-product methanol is distilled out; (2) Turn off the sublimation reflux device and remove the residual tetramethylpiperidinol by vacuum distillation; (3) Add hot water to the reaction solution obtained in step (2), stir, stand and separate the layers, and then remove the lower layer of water. The obtained washing solution is dehydrated by distillation to obtain the bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate product.
2. The method for preparing bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate according to claim 1, characterized in that: In step (1), the molar ratio of tetramethyl piperidinol to dimethyl sebacate is 2-61; the mass ratio of the catalyst, the color preservative, and tetramethyl piperidinol is 0.002-0.03:0.001-0.05:
1.
3. The method for preparing bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate according to claim 1, characterized in that: In step (1), the catalyst is one or more of tetra-n-butyl titanate, tetra-isopropyl titanate, aluminum isopropoxide, sodium methoxide, lithium amide, and dibutyltin oxide.
4. The method for preparing bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate according to claim 1, characterized in that: In step (1), the color preserving additive is one or more of sodium borohydride, potassium borohydride, sodium triacetoxyborohydride, sodium sulfite, sodium bisulfite, sodium bisulphite, sodium dithionite, and hydrazine hydrate.
5. The method for preparing bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate according to claim 1, characterized in that: In step (1), the temperature is raised to 90-130° C. under normal pressure and stirred to carry out the reaction.
6. The method for preparing bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate according to claim 1, characterized in that: In step (1), the temperature of the sublimation reflux device is set to 110-160°C.
7. The method for preparing bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate according to claim 1, characterized in that: In step (1), the reduced pressure reaction temperature is 120-150°C, and the reduced pressure reaction pressure is -0.02 to -0.095 MPa.
8. The method for preparing bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate according to claim 1, characterized in that: In step (2), the temperature for removing the residual tetramethylpiperidinol by vacuum distillation is 120-160° C. and the pressure is -0.02 to -0.095 MPa.