A method for synthesizing sodium ethoxide using ethyl trifluoroacetylacetate by-product ethanol

Abstract

The present application relates to a kind of method for synthesizing sodium ethoxide by trifluoroacetyl ethyl acetate byproduct ethanol, belong to the technical field of fine chemical industry.The present application obtains the byproduct ethanol as raw material when rectifying trifluoroacetyl ethyl acetate;Then the following steps are carried out in turn: (1) the byproduct ethanol of raw material is first subjected to rectification;(2) water is removed by benzene azeotrope water combination alkali method reaction;(3) sodium is added to remove water deeply, and sodium ethoxide is obtained.The present application realizes the high-value resource utilization of trifluoroacetyl ethyl acetate byproduct ethanol, converts the byproduct ethanol originally as low-value fuel into high-value-added sodium ethoxide product, reduces the raw material cost and environmental protection treatment cost of enterprise, and has significant economic benefit and environmental protection benefit.

Description

Technical Field

[0001] This invention relates to the technical field of fine chemicals, and specifically to a method for synthesizing sodium ethoxide using ethanol, a byproduct of ethyl trifluoroacetoacetate. Background Technology

[0002] Ethyl trifluoroacetoacetate is an important fluorine-containing fine chemical intermediate, widely used in the synthesis of pharmaceuticals, pesticides, liquid crystal materials, and fluorine-containing compounds. Its industrial synthesis primarily involves the reaction of ethyl trifluoroacetate and ethyl acetate as raw materials via a Claisen condensation reaction under alkaline catalysis. This reaction generates a large amount of ethanol as a byproduct (the byproduct contains approximately 80%–90% ethanol, with the remainder consisting of small amounts of ethyl acetate, ethyl trifluoroacetoacetate, and water, among other impurities). Ethyl acetate undergoes saponification under strongly alkaline conditions, consuming the alkali source and introducing impurities. Ethyl trifluoroacetoacetate, as a fluorinated ester containing active methylene groups, readily undergoes decarboxylation, decomposition, and condensation reactions in strongly alkaline systems, generating colored tar and impurities, leading to a decrease in product purity. Furthermore, the high water content prevents the direct use of this byproduct ethanol in the preparation of sodium ethoxide; currently, it is mostly treated as a low-value fuel, resulting in resource waste and increased environmental treatment costs.

[0003] In existing technologies, benzene and cyclohexane are commonly used as azeotropic dehydrating agents in the alkaline process for preparing sodium ethoxide. Azeotropic distillation removes the water generated in the reaction, shifting the reaction equilibrium to the right. However, this process can only handle anhydrous ethanol with low moisture content (typically ≤0.5%). It is not directly suitable for byproduct ethanol containing higher moisture content and certain ester impurities. Furthermore, due to its limited dehydration efficiency, azeotropic dehydration alone is insufficient to completely remove moisture from the system, limiting the equilibrium conversion rate. Even after azeotropic dehydration, trace amounts of moisture remain, easily leading to the hydrolysis of sodium ethoxide and further reducing product yield and purity.

[0004] If sodium metal is used directly for deep dehydration, the high water and impurity content in the byproduct ethanol will lead to a large consumption of sodium metal and violent side reactions, which will not only increase costs but also generate a large number of impurities, affecting product quality.

[0005] In the existing technology, there are no reports on the resource utilization of ethanol, a byproduct of the synthesis of ethyl trifluoroacetoacetate, or on the preparation of sodium ethoxide using an alkaline method combining benzene azeotropic dehydration and deep dehydration with metallic sodium. How to solve the problems of impurities in the byproduct ethanol, incomplete dehydration, and low yield and purity, and achieve high-value utilization of the byproduct ethanol and low-cost, high-yield, and green preparation of sodium ethoxide, has become an urgent technical challenge to be solved in this field. Summary of the Invention

[0006] To address the technical problems of incomplete ethanol dehydration and low yield in existing ethanol recovery processes for sodium ethoxide production, this invention provides a method for synthesizing sodium ethoxide using ethanol, a byproduct of ethyl trifluoroacetoacetate, to solve these problems. This invention achieves a synergistic effect by combining pretreatment distillation for impurity removal, alkaline reaction with benzene azeotropic water removal, and deep dehydration with metallic sodium. This completely breaks the reversible reaction equilibrium, significantly improving the reaction conversion rate, realizing the resource utilization of the byproduct ethanol, and simultaneously producing high-purity sodium ethoxide, reducing production costs and environmental impact.

[0007] The technical solution of this invention is as follows: A method for synthesizing sodium ethoxide from ethanol, a byproduct of ethyl trifluoroacetoacetate, uses ethanol, a byproduct obtained during the distillation of ethyl trifluoroacetoacetate, as a raw material, comprising 1%–5% water, trace amounts of ethyl acetate, and ethyl trifluoroacetoacetate; then the following steps are performed sequentially: (1) The raw material by-product ethanol is first distilled; (2) water is removed by benzene azeotropic water removal combined with alkaline reaction; (3) sodium metal is used for deep water removal, and sodium ethoxide is prepared at the same time.

[0008] The ethanol obtained in step (1) has an ethanol content of ≥99.5%, a water content of ≤0.3%, and an ethyl acetate content of ≤500ppm.

[0009] Further, the specific steps of step (1) are as follows: the by-product ethanol is sent to a distillation column for distillation treatment, and the distillation conditions are controlled as follows: the top temperature of the distillation column is 77℃~79℃, the bottom temperature is 105℃~115℃, the reflux ratio is 2~5:1, and the middle fraction is collected as refined ethanol; among them, the top fraction (mainly containing ethyl acetate, because the atmospheric boiling point of ethyl acetate is 77.1℃, which is slightly lower than the boiling point of ethanol 78.4℃) is collected separately, and the bottom residue (mainly containing ethyl trifluoroacetoacetate, whose atmospheric boiling point is 130℃~135℃, which is a high-boiling substance) is retained for subsequent processing.

[0010] Further, step (2) specifically involves: feeding the refined ethanol obtained in step (1) into a reaction vessel, adding solid sodium hydroxide and benzene, and stirring until homogeneous. The mass ratio of sodium hydroxide to refined ethanol is 1:8~12, and the volume ratio of benzene to refined ethanol is 0.8~1.2:1. Nitrogen gas is introduced into the reaction vessel to remove air and moisture, preventing the hydrolysis of sodium ethoxide and subsequent reactions of metallic sodium from causing danger. The reaction vessel is heated to 78~82℃ and subjected to reflux azeotropic distillation. Benzene, ethanol, and water form a ternary azeotrope (the benzene-ethanol-water ternary azeotrope contains approximately 7.4% water). After condensation, the azeotropic distillate enters a water separator, is allowed to stand and separate into layers. The upper layer is the benzene phase, which is refluxed back to the reaction vessel for recycling, and the lower layer is the aqueous phase, which is discharged and collected. Reflux azeotropic distillation continues for 2~4 hours until no obvious aqueous phase is separated in the water separator. Azeotropic distillation is then stopped to obtain a preliminary sodium ethoxide solution. In step (2), benzene, as an azeotropic dehydrating agent, can efficiently remove the water generated in the reaction and the residual water in the purified ethanol, promote the positive equilibrium of the alkaline reaction, reduce the hydrolysis of sodium ethoxide, and at the same time avoid the influence of excessive water on the subsequent deep dehydration of metallic sodium.

[0011] Further, step (3) specifically involves: cooling the initial sodium ethoxide solution obtained in step (2) to 25-35°C, and slowly adding sodium metal particles under inert gas protection. The molar ratio of sodium metal to residual water in the initial sodium ethoxide solution is 1.1-1.3:1. After adding sodium metal, the mixture is stirred for 1-2 hours. The sodium metal reacts with the residual water to generate sodium hydroxide and hydrogen (2Na + 2H2O = 2NaOH + H2). At the same time, the unreacted sodium metal can further react with ethanol to generate sodium ethoxide (2C2H5OH + 2Na = 2C2H5ONa + H2), achieving deep dehydration while further improving the yield of sodium ethoxide. After the reaction is completed, the trace solid impurities generated by the reaction are removed by filtration to obtain a purified sodium ethoxide solution. If solid sodium ethoxide needs to be prepared, the purified sodium ethoxide solution can be subjected to vacuum distillation to remove excess ethanol and benzene, and then dried to obtain the solid sodium ethoxide product.

[0012] Furthermore, the top fraction (containing ethyl acetate) collected in step (1) can be returned to the ethyl trifluoroacetoacetate synthesis process as a raw material for recycling; the aqueous phase discharged in step (2) can be recycled by distillation to recover a small amount of ethanol; the ethanol and benzene recovered by vacuum distillation in step (3) can be returned to step (2) for recycling after purification by distillation, thus realizing the closed-loop utilization of resources.

[0013] Furthermore, in step (1), the distillation column is a packed column, the packing is stainless steel Pall rings, and the number of trays is 20 to 30, which can improve the distillation separation efficiency and ensure the removal of impurities.

[0014] Furthermore, in step (2), the purity of the sodium hydroxide solid is ≥98%, and the particle size of the metallic sodium particles is 2~5mm, which facilitates the control of the reaction rate and avoids the reaction being too violent; the nitrogen gas is introduced at a rate of 0.5~1.0L / min to ensure that the air and moisture in the reactor are completely discharged.

[0015] Furthermore, in step (3), the sodium metal particles are added at a rate of 0.5~1.0 g / min to prevent excessive local reaction from causing danger; the stirring rate is 150~200 r / min to ensure that the sodium metal and the initial sodium ethoxide solution are in full contact, thereby improving the deep dehydration effect.

[0016] Furthermore, in step (3), the conditions for vacuum distillation are: vacuum degree -0.08~-0.09MPa, temperature 60℃~70℃, which can remove ethanol and benzene at a lower temperature and avoid the decomposition of sodium ethoxide.

[0017] The beneficial effects of this invention are as follows: (1) This invention realizes the high-value resource utilization of ethanol, a by-product of ethyl trifluoroacetoacetate, and transforms ethanol, which was originally a low-value fuel, into a high-value sodium ethoxide product, thereby reducing the raw material cost and environmental treatment cost of enterprises, and has significant economic and environmental benefits.

[0018] (2) In view of the impurity characteristics of the by-product ethanol (containing ethyl acetate and ethyl trifluoroacetoacetate), the present invention adds a distillation pretreatment process. By controlling the distillation conditions, the two ester impurities are effectively separated and removed, avoiding the consumption of alkali source and the generation of impurities in subsequent reactions, thus ensuring product purity.

[0019] (3) The present invention adopts a synergistic dehydration scheme of benzene azeotropic water removal and deep dehydration of metallic sodium. First, most of the water is removed by benzene azeotropic water removal, and then the residual water is reduced to an extremely low level (≤0.05%) by deep dehydration of metallic sodium. This solves the problems of water inhibition balance and sodium ethoxide hydrolysis in alkaline reaction. At the same time, metallic sodium can further react with ethanol to generate sodium ethoxide, thereby improving the product yield.

[0020] (4) This invention realizes the recycling of by-products (ethyl acetate, ethanol, benzene), reduces resource waste and lowers production costs; the entire process is safe and controllable, suitable for large-scale industrial production, and the prepared sodium ethoxide product has a purity of ≥98% and a yield of ≥92%, meeting the needs of industrial applications. (5) Compared with the traditional sodium metal method, the present invention first prepares primary sodium ethoxide by alkaline method combined with azeotropic water removal, and then uses sodium metal for deep water removal, which greatly reduces the amount of sodium metal used, reduces the operation risk and raw material cost. Compared with the traditional alkaline azeotropic dehydration process, the present invention is suitable for by-product ethanol with high moisture content and specific impurities, which broadens the source of raw materials. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0022] The ethanol byproduct of ethyl trifluoroacetoacetate used in the following examples was obtained in the following manner: The molar ratio of ethyl trifluoroacetate:sodium ethoxide:ethyl acetate is 1:1.15:3.

[0023] (1) Measure and transfer ethyl acetate and sodium ethoxide into the reaction vessel and stir for 30 min to disperse them completely; (2) Cool the temperature to below 10°C and slowly add ethyl trifluoroacetate at a uniform rate; (3) After the addition is complete, slowly raise the temperature to 35℃~40℃ and keep it at that temperature for 6 hours. Take a sample and test the residual amount of ethyl trifluoroacetate in the raw material. The residual amount is ≤0.5%. (4) Cool down to 0~15℃ and slowly add 30% hydrochloric acid to adjust pH to 2~3; (5) Allow to stand and separate the liquids; extract the aqueous phase a second time with ethyl acetate and combine the organic phases; (6) First, perform fractional solvent removal under normal pressure. Collect unreacted ethyl trifluoroacetate at 58℃~63℃, collect ethyl acetate at 64℃~77.5℃, and start collecting the byproduct ethanol at 77.5℃. Stop solvent removal under normal pressure when the kettle temperature reaches 90℃. Then, perform negative pressure distillation to collect the product ethyl trifluoroacetoacetate.

[0024] Example 1 A method for synthesizing sodium ethoxide using ethanol, a byproduct of ethyl trifluoroacetoacetate, is as follows: (1) Pretreatment of byproduct ethanol 1000 kg of ethanol, a byproduct of the synthesis of ethyl trifluoroacetoacetate, was taken. Its composition was: 85% ethanol, 3% water, 0.8% ethyl acetate, and 0.2% ethyl trifluoroacetoacetate. It was fed into a packed column (stainless steel Pall ring packing, 25 trays) for distillation. The top temperature of the column was controlled at 78℃, the bottom temperature at 110℃, and the reflux ratio at 3:1. 820 kg of the middle fraction was collected as purified ethanol. The top fraction (containing ethyl acetate) was collected for later use, and the bottom residue was retained for further processing. The purified ethanol was tested and found to have the following characteristics: ethanol content 99.6%, water content 0.25%, ethyl acetate content 380 ppm, and ethyl trifluoroacetoacetate was not detected.

[0025] (2) Benzene azeotropic reaction with water and alkali 820 kg of purified ethanol was fed into a reaction vessel, along with 82 kg of solid sodium hydroxide (98% purity) and 820 L of benzene, and stirred until homogeneous. Nitrogen gas was introduced into the reaction vessel at a rate of 0.8 L / min to remove air and moisture. The reaction vessel was heated to 80 °C and subjected to reflux azeotropic distillation. The azeotrope was condensed and then transferred to a water separator. After standing and separating, the upper benzene phase was refluxed back into the reaction vessel, while the lower aqueous phase was discharged and collected. Reflux azeotropic distillation was continued for 3 hours until no obvious aqueous phase was separated. Distillation was then stopped to obtain a primary sodium ethoxide solution.

[0026] (3) Deep dehydration and refining of metallic sodium The initial sodium ethoxide solution was cooled to 30°C, and under nitrogen protection, metallic sodium particles (3 mm in diameter) were added at a rate of 0.8 g / min. The amount of metallic sodium used was 1.2 kg (the molar ratio of sodium to residual water in the initial sodium ethoxide solution was 1.2:1). After the addition was complete, the mixture was stirred at 180 r / min for 1.5 h. After the reaction was completed, trace solid impurities were removed by filtration to obtain a purified sodium ethoxide solution. The purified sodium ethoxide solution was then distilled under reduced pressure at a vacuum of -0.085 MPa and a temperature of 65°C to remove excess ethanol and benzene. After drying, 128 kg of solid sodium ethoxide product was obtained.

[0027] The solid sodium ethoxide product was tested and found to have a purity of 98.5% and a yield of 92.1%.

[0028] (4) By-product recovery and recycling The top fraction collected in step (1) is returned to the ethyl trifluoroacetoacetate synthesis process as raw material; the aqueous phase discharged in step (2) is distilled to recover 5.2 kg of ethanol, which is then returned to step (2) for use; in step (3), 720 kg of ethanol and 815 L of benzene are recovered by vacuum distillation, and after purification by distillation, they are returned to step (2) for recycling.

[0029] Example 2 A method for synthesizing sodium ethoxide using ethanol, a byproduct of ethyl trifluoroacetoacetate, is as follows: (1) Pretreatment of byproduct ethanol 1000 kg of ethanol, a byproduct of the synthesis of ethyl trifluoroacetoacetate, was taken. Its composition was: 80% ethanol, 5% water, 1.0% ethyl acetate, and 0.3% ethyl trifluoroacetoacetate. It was fed into a packed column (stainless steel Pall ring packing, 30 trays) for distillation. The top temperature of the column was controlled at 77℃, the bottom temperature at 115℃, and the reflux ratio at 5:1. 780 kg of the middle fraction was collected as purified ethanol. The top fraction was collected for later use, and the bottom residue was retained for further processing. The purified ethanol was tested and found to have the following characteristics: ethanol content 99.5%, water content 0.3%, ethyl acetate content 490 ppm, and ethyl trifluoroacetoacetate was not detected.

[0030] (2) Benzene azeotropic reaction with water and alkali 780 kg of purified ethanol was fed into a reaction vessel, along with 65 kg of solid sodium hydroxide (98% purity) and 936 L of benzene, and stirred until homogeneous. Argon gas was introduced into the reaction vessel at a rate of 1.0 L / min to remove air and moisture. The reaction vessel was heated to 82 °C and subjected to reflux azeotropic distillation. The azeotrope was condensed and fed into a separatory funnel, where it was allowed to separate into layers. The upper benzene phase was refluxed back into the reaction vessel, while the lower aqueous phase was discharged and collected. Reflux azeotropic distillation was continued for 4 hours until no obvious aqueous phase was separated, at which point the distillation was stopped, yielding a primary sodium ethoxide solution.

[0031] (3) Deep dehydration and refining of metallic sodium The initial sodium ethoxide solution was cooled to 35°C, and under argon protection, metallic sodium particles (5 mm in diameter) were added at a rate of 1.0 g / min. The amount of metallic sodium used was 1.5 kg (the molar ratio of sodium to residual water in the initial sodium ethoxide solution was 1.3:1). After the addition was complete, the mixture was stirred at 200 r / min for 2 h. After the reaction was completed, trace solid impurities were removed by filtration to obtain a purified sodium ethoxide solution. The purified sodium ethoxide solution was then distilled under reduced pressure at a vacuum of -0.09 MPa and a temperature of 70°C to remove excess ethanol and benzene. After drying, 101.5 kg of solid sodium ethoxide product was obtained.

[0032] The solid sodium ethoxide product was tested and found to have a purity of 98.2% and a yield of 91.5%.

[0033] (4) By-product recovery and recycling The top fraction collected in step (1) is returned to the ethyl trifluoroacetoacetate synthesis process as raw material; the aqueous phase discharged in step (2) is distilled to recover 6.8 kg of ethanol, which is then returned to step (2) for use; in step (3), 690 kg of ethanol and 930 L of benzene are recovered by vacuum distillation, and after purification by distillation, they are returned to step (2) for recycling.

[0034] Example 3 A method for synthesizing sodium ethoxide using ethanol, a byproduct of ethyl trifluoroacetoacetate, is as follows: (1) Pretreatment of byproduct ethanol 1000 kg of ethanol, a byproduct of the synthesis of ethyl trifluoroacetoacetate, was taken. Its composition was: 90% ethanol, 1% water, 0.5% ethyl acetate, and 0.1% ethyl trifluoroacetoacetate. It was fed into a packed column (stainless steel Pall ring packing, 20 trays) for distillation. The top temperature of the column was controlled at 79℃, the bottom temperature at 105℃, and the reflux ratio at 2:1. 880 kg of the middle fraction was collected as purified ethanol. The top fraction was collected for later use, and the bottom residue was retained for further processing. The purified ethanol was tested and found to have the following characteristics: ethanol content 99.8%, water content 0.1%, ethyl acetate content 250 ppm, and ethyl trifluoroacetoacetate was not detected.

[0035] (2) Benzene azeotropic reaction with water and alkali 880 kg of purified ethanol was fed into a reaction vessel, along with 97 kg of solid sodium hydroxide (98% purity) and 704 L of benzene, and stirred until homogeneous. Nitrogen gas was introduced into the reaction vessel at a rate of 0.5 L / min to remove air and moisture. The reaction vessel was heated to 78 °C and subjected to reflux azeotropic distillation. The azeotrope was condensed and fed into a separatory funnel, where it was allowed to separate into layers. The upper benzene phase was refluxed back into the reaction vessel, while the lower aqueous phase was discharged and collected. Reflux azeotropic distillation was continued for 2 hours until no obvious aqueous phase was separated, at which point the distillation was stopped, yielding a primary sodium ethoxide solution.

[0036] (3) Deep dehydration and refining of metallic sodium The initial sodium ethoxide solution was cooled to 25°C, and under nitrogen protection, metallic sodium particles (2 mm in diameter) were added at a rate of 0.5 g / min. The amount of metallic sodium used was 0.8 kg (the molar ratio of sodium to residual water in the initial sodium ethoxide solution was 1.1:1). After the addition was complete, the mixture was stirred at 150 r / min for 1 h. After the reaction was completed, trace solid impurities were removed by filtration to obtain a purified sodium ethoxide solution. The purified sodium ethoxide solution was then distilled under reduced pressure at a vacuum of -0.08 MPa and a temperature of 60°C to remove excess ethanol and benzene. After drying, 151.3 kg of solid sodium ethoxide product was obtained.

[0037] The solid sodium ethoxide product was tested and found to have a purity of 98.8% and a yield of 92.8%.

[0038] (4) By-product recovery and recycling The top fraction collected in step (1) is returned to the ethyl trifluoroacetoacetate synthesis process as raw material; the aqueous phase discharged in step (2) is distilled to recover 3.5 kg of ethanol, which is then returned to step (2) for use; in step (3), 780 kg of ethanol and 700 L of benzene are recovered by vacuum distillation, and after purification by distillation, they are returned to step (2) for recycling.

[0039] Comparative Example 1 A method for synthesizing sodium ethoxide using ethanol, a byproduct of ethyl trifluoroacetoacetate, employs the traditional benzene azeotropic alkaline process, using anhydrous ethanol as raw material, and without performing a deep dehydration operation for sodium. The specific steps are as follows: (1) Take 820 kg of pure anhydrous ethanol (ethanol content ≥ 99.9%, water content ≤ 0.05%, free of ethyl acetate and ethyl trifluoroacetoacetate impurities) and send it into the reaction vessel; (2) Add 82 kg of sodium hydroxide solid (98% purity) and 820 L of benzene to the reactor and stir evenly; purge nitrogen gas (purge rate 0.8 L / min) to remove air and moisture from the reactor, heat the reactor to 80 °C, and reflux azeotropic distillation for 3 h until no obvious aqueous phase is separated, then stop distillation to obtain sodium ethoxide solution. (3) The sodium ethoxide solution was distilled under reduced pressure at a vacuum of -0.085 MPa and a temperature of 65 °C to remove excess ethanol and benzene. After drying, 126.9 kg of solid sodium ethoxide product was obtained. The solid sodium ethoxide product was tested and found to have a purity of 97.2% and a yield of 88.5%. The product showed no obvious discoloration and the impurity content was within acceptable limits. However, the yield was lower than that of Examples 1-3 of this invention, and the raw material was pure anhydrous ethanol, which was much more expensive than the byproduct ethanol used in Examples 1-3.

[0040] Comparative Example 2 A method for synthesizing sodium ethoxide using ethanol, a byproduct of ethyl trifluoroacetoacetate, involves directly preparing sodium ethoxide from ethanol, a byproduct of ethyl trifluoroacetoacetate synthesis, by only performing purification of the byproduct ethanol and benzene azeotropic operation, but without performing deep dehydration of sodium.

[0041] (1) Pretreatment of byproduct ethanol 1000 kg of ethanol (composition: 85% ethanol, 3% water, 0.8% ethyl acetate, and 0.2% ethyl trifluoroacetoacetate) was collected as a byproduct of ethyl trifluoroacetoacetate synthesis and fed into a packed column (stainless steel Pall ring packing, 25 trays) for distillation. The top temperature was controlled at 78℃, the bottom temperature at 110℃, and the reflux ratio at 3:1. 820 kg of the middle fraction was collected as refined ethanol. The top fraction (containing ethyl acetate) was collected for later use, and the bottom residue was retained for further processing. The refined ethanol was tested and found to have the following specifications: ethanol content 99.6%, water content 0.25%, ethyl acetate content 380 ppm, and ethyl trifluoroacetoacetate not detected.

[0042] (2) Benzene azeotropic reaction with water and alkali 820 kg of purified ethanol was fed into a reaction vessel, and then 82 kg of sodium hydroxide solid (98% purity) and 820 L of benzene were added to the reaction vessel and stirred evenly. Nitrogen gas was introduced (at a rate of 0.8 L / min) to remove air and moisture from the vessel. The reaction vessel was heated to 80 °C and refluxed for azeotropic distillation for 3 hours until no obvious aqueous phase was separated. Distillation was then stopped to obtain a sodium ethoxide solution.

[0043] (3) Direct refining process The sodium ethoxide solution obtained in step (2) was filtered to remove trace solid impurities. Then, it was distilled under reduced pressure at a vacuum of -0.085 MPa and a temperature of 65°C to remove excess ethanol and benzene. After drying, 126.1 kg of solid sodium ethoxide product was obtained.

[0044] Testing revealed that the purity of the solid sodium ethoxide product was 95.6%, with a yield of 86.5%. The product was yellowish-black and contained tar-like impurities. This was because the saponification of ethyl acetate in the by-product ethanol consumed the alkali source, and the decomposition of ethyl trifluoroacetoacetate produced impurities. Furthermore, the product was not subjected to deep sodium dehydration, and the residual moisture caused partial hydrolysis of the sodium ethoxide. As a result, the product quality did not meet the requirements for industrial applications.

[0045] Comparative Example 3 A method for synthesizing sodium ethoxide using ethanol, a byproduct of ethyl trifluoroacetoacetate, involves directly preparing sodium ethoxide from ethanol, a byproduct of ethyl trifluoroacetoacetate synthesis, and performing purification of the byproduct ethanol and deep dehydration of sodium, but without employing a benzene azeotropic process.

[0046] (1) Pretreatment of byproduct ethanol 1000 kg of ethanol (composition: 85% ethanol, 3% water, 0.8% ethyl acetate, and 0.2% ethyl trifluoroacetoacetate) was taken as a byproduct of the synthesis of ethyl trifluoroacetoacetate and fed into a packed column (stainless steel Pall ring packing, 25 trays) for distillation. The top temperature was controlled at 78℃, the bottom temperature at 110℃, and the reflux ratio at 3:1. 820 kg of the middle fraction was collected as refined ethanol. The top fraction (containing ethyl acetate) was collected for later use, and the bottom residue was retained for further processing. The refined ethanol was tested and found to have the following characteristics: ethanol content 99.6%, water content 0.25%, ethyl acetate content 380 ppm, and ethyl trifluoroacetoacetate was not detected.

[0047] (2) Benzene-free azeotropic alkaline reaction 820 kg of refined ethanol was fed into a reactor, and then 82 kg of sodium hydroxide solid (98% purity) was added to the reactor. The mixture was stirred until homogeneous. No benzene was added to the system, and no azeotropic reflux was performed to remove water. Nitrogen gas was introduced into the reactor at a rate of 0.8 L / min to remove air and moisture from the reactor. The reactor was heated to 80°C and stirred under constant temperature for 3 hours. There was no water separation or circulation process. After the reaction, a primary sodium ethoxide solution containing hydrolyzed impurities was obtained.

[0048] (3) Deep dehydration and refining of metallic sodium The initial sodium ethoxide solution obtained in step (2) was cooled to 30°C, and sodium metal particles (3 mm in diameter) were added at a rate of 0.8 g / min. The amount of sodium metal was 58.5 kg (the molar ratio of sodium metal to the residual water in the initial sodium ethoxide solution was 1.2:1). The mixture was stirred at a rate of 180 r / min for 1.5 h. After the reaction was completed, a large amount of solid impurities were removed by filtration. The filtrate was then distilled under reduced pressure at a vacuum of -0.085 MPa and a temperature of 65°C. After drying, 128.2 kg of solid sodium ethoxide product was obtained.

[0049] Testing revealed that the purity of the solid sodium ethoxide product was 94%, with a yield of 85.2%. This comparative example retained the raw material refining and deep sodium dehydration processes, but lacked the benzene azeotropic pre-dehydration process. As a result, a large amount of free water in the early stages of the system could not be efficiently removed, significantly increasing the dehydration load of the metallic sodium. The excessive sodium dosage would generate a large amount of byproduct alkali, resulting in a large amount of solid residue and high filtration loss. The product purity and yield were lower than those of Comparative Examples 1 and 2, and significantly worse than Examples 1-3, fully demonstrating the synergistic effect of benzene azeotropic water removal and deep sodium dehydration.

[0050] Comparative Example 4 A method for synthesizing sodium ethoxide using ethanol, a byproduct of ethyl trifluoroacetoacetate, is disclosed. Sodium ethoxide is directly prepared using ethanol, a byproduct of ethyl trifluoroacetoacetate synthesis, without distillation and purification pretreatment. The method retains the benzene azeotropic water-carrying combined with alkaline reaction and deep sodium dehydration purification process to prepare sodium ethoxide.

[0051] (1) Take 1000 kg of ethanol (composition: 85% ethanol, 3% water, 0.8% ethyl acetate, and 0.2% ethyl trifluoroacetoacetate) as a byproduct of the synthesis of ethyl trifluoroacetoacetate and send it directly into the reactor.

[0052] (2) Benzene azeotropic reaction with water and alkali Add 82 kg of solid sodium hydroxide (98% purity) and 820 L of benzene, and stir until homogeneous. Purge nitrogen gas into the reactor at a rate of 0.8 L / min to remove air and moisture from the reactor. Heat the reactor to 80 °C and perform reflux azeotropic distillation. After condensation, the azeotrope enters a water separator, is allowed to stand and separate into layers. The upper benzene phase is refluxed back into the reactor, and the lower aqueous phase is discharged and collected. Continue reflux azeotropic distillation for 3 hours until no obvious aqueous phase is separated, then stop distillation to obtain a preliminary sodium ethoxide solution.

[0053] (3) Deep dehydration and refining of metallic sodium The initial sodium ethoxide solution was cooled to 30°C, and under nitrogen protection, 1.2 kg of metallic sodium particles (3 mm in diameter) were added at a rate of 0.8 g / min. After the addition was complete, the mixture was stirred at 180 r / min for 1.5 h. After the reaction was completed, trace solid impurities were removed by filtration to obtain a purified sodium ethoxide solution. The purified sodium ethoxide solution was then distilled under reduced pressure at a vacuum of -0.085 MPa and a temperature of 65°C to remove excess ethanol and benzene. After drying, 127.3 kg of solid sodium ethoxide product was obtained.

[0054] Testing revealed that the purity of the solid sodium ethoxide product was 93.3%, with a yield of 85.0%. This comparative example retained the synergistic process of benzene azeotropic pre-dehydration and deep dehydration of metallic sodium, but did not refine the byproduct ethanol through distillation. Ethyl acetate, trace amounts of ethyl trifluoroacetoacetate, and high moisture content impurities in the raw materials participated in the reaction, initiating side reactions and exacerbating hydrolysis, significantly impacting the reaction conversion rate and product purity. The product purity and yield were the lowest among all experimental groups, significantly lower than Examples 1-3 and Comparative Examples 1-3, verifying the crucial role of the byproduct ethanol refining pretreatment process in improving product quality and yield.

[0055] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A method for synthesizing sodium ethoxide from ethanol, a byproduct of ethyl trifluoroacetoacetate, characterized in that, Using ethanol, a byproduct obtained during the distillation of ethyl trifluoroacetoacetate, as a raw material, the following steps are then performed sequentially: (1) The raw material byproduct ethanol is first distilled; (2) water is removed by benzene azeotropic water removal combined with alkaline reaction; (3) sodium metal is added for deep water removal to obtain sodium ethoxide.

2. The method as described in claim 1, characterized in that, The specific steps of step (1) are as follows: the by-product ethanol is sent to a distillation column for distillation treatment, and the distillation conditions are controlled as follows: the top temperature of the distillation column is 77℃~79℃, the bottom temperature is 105℃~115℃, and the reflux ratio is 2~5:

1.

3. The method as described in claim 1, characterized in that, The specific steps (2) are as follows: the refined ethanol obtained in step (1) is fed into the reaction vessel, sodium hydroxide solid and benzene are added and stirred evenly; the reaction vessel is heated to 78℃~82℃ and reflux azeotropic distillation is carried out. Benzene, ethanol and water form a ternary azeotrope, which is condensed and then enters the water separator. It is allowed to stand and separate into layers. The upper layer is the benzene phase, which is refluxed back to the reaction vessel for recycling. The lower layer is the aqueous phase, which is discharged and collected. Reflux azeotropic distillation is continued for 2~4 hours until no obvious aqueous phase is separated in the water separator. Azeotropic distillation is then stopped to obtain the initial sodium ethoxide solution.

4. The method as described in claim 3, characterized in that, The mass ratio of sodium hydroxide to purified ethanol is 1:8~12, and the volume ratio of benzene to purified ethanol is 0.8~1.2:

1.

5. The method as described in claim 1, characterized in that, The specific steps (3) are as follows: the initial sodium ethoxide solution obtained in step (2) is cooled to 25℃~35℃, and sodium metal particles are slowly added under the protection of an inert gas. The molar ratio of sodium metal to residual water in the initial sodium ethoxide solution is 1.1~1.3:

1. After adding sodium metal, the mixture is stirred for 1~2 hours. After the reaction is completed, the purified sodium ethoxide solution is obtained by filtration.

6. The method as described in claim 2, characterized in that, The top fraction collected in step (1) is returned to the ethyl trifluoroacetoacetate synthesis process as a raw material for recycling; the aqueous phase discharged in step (2) is distilled and a small amount of ethanol is recovered for recycling; the ethanol and benzene recovered by vacuum distillation in step (3) are purified by distillation and returned to step (2) for recycling, thus realizing the closed-loop utilization of resources.

7. The method as described in claim 2, characterized in that, In step (1), the distillation column is a packed column, the packing is stainless steel Pall rings, and the number of trays is 20 to 30.

8. The method as described in claim 3, characterized in that, In step (2), the purity of the sodium hydroxide solid is ≥98%, the particle size of the sodium metal particles is 2~5mm, and the nitrogen gas introduction rate is 0.5~1.0L / min.

9. The method as described in claim 5, characterized in that, In step (3), the sodium metal particles are added at a rate of 0.5~1.0 g / min and the stirring rate is 150~200 r / min.

10. The method as described in claim 5, characterized in that, In step (3), the conditions for vacuum distillation are: vacuum degree -0.08~-0.09MPa, temperature 60℃~70℃.