A process for synthesizing electronic-grade 2,2-difluoroethyl acetate

Abstract

The present application discloses a process for synthesizing electronic-grade acetic acid 2,2-difluoroethyl esters, including the following process steps: S1, the raw material containing acetic acid and 2,2-difluoroethanol is pre-reacted in a pre-reactor to obtain a liquid mixture; S2, the above-mentioned liquid mixture and water are entered into a rectifying tower 1 for catalytic reaction, overhead distillate is extracted, and aqueous phase I and ester phase I are separated by standing; S3, the above-mentioned aqueous phase I is entered into a rectifying tower 2 for further rectification, overhead extraction and static separation obtain aqueous phase II and ester phase II; the aqueous phase II is circulated into a rectifying tower 2; S4, the ester phase obtained in steps S2 and S3 is subjected to alkali washing and acid removal, dehydration, then enters a rectifying tower 4 for rectification and purification, and side mining obtains electronic-grade acetic acid 2,2-difluoroethyl esters. This process method has high product purity, small moisture content, fast separation speed, low energy consumption, does not produce waste acid, and materials can be substantially all recycled, only producing a small amount of waste water, and the entire process is more environmentally friendly.

Description

Technical Field

[0001] The present application relates to a process for synthesizing electronic-grade 2,2-difluoroethyl acetate, belonging to the field of battery electrolyte additive methods. Background Art

[0002] With the research and development of portable electronic devices and new energy vehicles, the demand for lithium-ion batteries as high-energy-density batteries has increased significantly. As one of the three elements of lithium-ion batteries, the electrolyte accounts for 20% to 30% of the total battery raw material cost and is a key factor affecting the performance of lithium-ion batteries. Actively developing an electrolyte system with superior performance and low price has great practical significance, which can further reduce the industrialization cost of lithium-ion batteries and improve market competitiveness.

[0003] The electrolyte not only determines the + The migration rate in the liquid phase also participates in the formation of the SEI film, playing a key role in the performance of the SEI film. At low temperatures, the viscosity of the electrolyte increases, the conductivity decreases, the impedance of the SEI film increases, and the compatibility with the positive and negative electrode materials deteriorates, which greatly deteriorates the energy density and cycle performance of the battery. Fluorinated solvents are a feasible solution to many lithium battery problems. Fluorinated organic solvents have unique physical and chemical properties due to the very high electronegativity and low polarizability of fluorine atoms. Fluorinated solvents can be used as additives to form a LiF-rich solid electrolyte interface. The SEI layer induced by them is dense and stable, which is conducive to obtaining a uniform Li deposition morphology. As an important component of fluorinated solvents, 2,2-difluoroethyl acetate can greatly improve the high-temperature, room-temperature, and low-temperature cycling performance of the battery, while greatly improving the low-temperature storage performance.

[0004] Currently, there are very few publicly available methods and processes for synthesizing 2,2-difluoroethyl acetate. For example, the acylation method used in patent CN113698295A not only produces waste acid, but also has low production capacity and relatively poor purity, making it unsuitable for later industrialization. Similar products, such as methyl difluoroacetate, are currently disclosed: Patent JP6228043 hydrolyzes N,N-diethyldifluoroacetamide with potassium hydroxide to produce difluoroacetic acid, which is then esterified with methanol to produce methyl difluoroacetate; and patent CN102531895A discloses a method for fluorinating methyl dichloroacetate with a catalyst, potassium fluoride, at high temperature, followed by the addition of an organic solvent, cooling the system to below 0°C, and then distilling under reduced pressure and filtering to obtain methyl difluoroacetate. Patent CN114085151A discloses a method for preparing high-purity ethyl difluoroacetate, which uses difluoroacetyl dialkylamine and ethanol as raw materials and concentrated sulfuric acid as a catalyst to undergo an esterification reaction to obtain crude ethyl difluoroacetate, which is then distilled and rectified to obtain high-purity ethyl difluoroacetate with a purity of over 99% and a water content of under 500 ppm. Patent CN103864615A discloses a continuous non-catalytic process for preparing ethyl trifluoroacetate, which uses trifluoroacetyl chloride and ethanol through reactive distillation to produce ethyl trifluoroacetate, but the purity can only reach 99% and acidic wastewater is generated. Patent CN104710308A uses trifluoroacetic acid and ethanol as raw materials and a strongly acidic cation exchange resin as a catalyst. Ethanol is added dropwise at 40-50°C and atmospheric pressure for 20 minutes, and the reaction is then heated to reflux to separate the water and ethanol mixture to complete the reaction. The crude product is washed with water to remove excess ethanol, and then separated to obtain a qualified product, ethyl trifluoroacetate, with a water content of over 99.5% and less than 0.1%. Patent CN110343043A discloses a purification process for ethyl trifluoroacetate, which includes first washing crude ethyl trifluoroacetate with distilled water to remove most of the alcohol and a small amount of acid contained therein; then adsorbing the washed crude ethyl trifluoroacetate with a molecular sieve adsorbent; and finally rectifying the crude ethyl trifluoroacetate to obtain high-purity ethyl trifluoroacetate with a purity of over 99.9%, a water content of less than 5 ppm, and an acidity of less than 10 ppm.

[0005] Currently, there is a lack of research on the synthesis and purification of 2,2-difluoroethyl acetate. The obtained product has low purity and poor industrial application. Therefore, it is of great economic and social significance to develop a process route with low energy consumption, high atom economy, high purity of the obtained 2,2-difluoroethyl acetate product, and the ability to achieve continuous reaction. Summary of the Invention

[0006] According to one aspect of the present application, a process for synthesizing electronic-grade 2,2-difluoroethyl acetate is provided. The process uses acetic acid and 2,2-difluoroethanol as raw materials, and obtains a high-purity electronic-grade 2,2-difluoroethyl acetate product through processes such as synthetic distillation, product separation and by-product re-reaction circulation, alkali washing, dehydration, and distillation purification.

[0007] This application adopts the following technical solutions:

[0008] A process for synthesizing electronic-grade 2,2-difluoroethyl acetate comprises the following steps:

[0009] S1, pre-reacting raw materials containing acetic acid and 2,2-difluoroethanol in a pre-reactor to obtain a liquid mixture;

[0010] S2, the liquid mixture obtained in step S1 and water enter the distillation tower 1 for catalytic reaction, and the overhead distillate is collected and allowed to stand to separate into the aqueous phase I and the ester phase I;

[0011] S3, the aqueous phase I obtained in step S2 enters the distillation tower 2 for further distillation, and the overhead is extracted and statically separated to obtain aqueous phase II and ester phase II; the aqueous phase II is circulated into the distillation tower 2;

[0012] S4, the crude 2,2-difluoroethyl acetate is subjected to alkali washing to remove acid and dehydrate, and then enters the distillation tower 4 for distillation and purification, and electronic grade 2,2-difluoroethyl acetate is obtained by side sampling;

[0013] The crude 2,2-difluoroethyl acetate is the ester phase II obtained in step S3, the ester phase I obtained in step S2, or a mixture of the two.

[0014] Optionally, the step S1 is: pre-reacting the raw materials of acetic acid and 2,2-difluoroethanol in a pre-reactor to obtain a liquid mixture.

[0015] Optionally, the feed molar ratio of acetic acid to 2,2-difluoroethanol in step S1 is 0.5 to 3:1.

[0016] Optionally, the feed molar ratio of acetic acid to 2,2-difluoroethanol in step S1 is 1 to 3:1.

[0017] Optionally, the feed molar ratio of acetic acid to 2,2-difluoroethanol in step S1 is selected from any value of 1:1, 1:25, 1.5:1, 1.75:1, 2:1, 2.25:1, 2.5:1, 2.75:1, 3:1, or any range between the two.

[0018] Optionally, in step S1, the reaction temperature of the pre-reactor is 50-100° C., and the reaction time is 0.5-10 h.

[0019] Optionally, in step S1, the pre-reactor is a fixed bed reactor or a tank reactor.

[0020] Optionally, the molar ratio of the water to the 2,2-difluoroethanol in step S1 is 0.5 to 3:1.

[0021] Optionally, the molar ratio of the water to the 2,2-difluoroethanol in step S1 is selected from any value of 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, or any range between the two.

[0022] Optionally, in step S2, the extraction process conditions are: total reflux for 0.5 to 3 hours, then extraction from the top of the tower at a reflux ratio of 1 to 10:1, a top temperature of 82 to 84° C., a bottom temperature of 108 to 110° C., and a top extraction rate of 50 to 60 mL / h.

[0023] Optionally, the reflux ratio is selected from any value of 1:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or any range between the two;

[0024] Optionally, in step S2, the extraction process conditions are: full reflux for 0.5 to 1 hour, then extraction from the top of the tower at a reflux ratio of 1 to 3:1, the top temperature of the tower is 82 to 84°C, the bottom temperature of the tower is 108°C to 110°C, and the top extraction rate is 55 to 60 mL / h.

[0025] Optionally, the reflux ratio is selected from any value of 1:1, 1.5:1, 2:1, 2.5:1, 3:1, or any range between the two.

[0026] Optionally, step S2 further comprises continuously adding a raw material mixture of acetic acid, 2,2-difluoroethanol, and water to the bottom of the tower in a molar ratio of 5 to 10:5 to 10:7 at a feeding rate of 30 to 300 mL / h;

[0027] Optionally, the feeding rate is 30 to 120 mL / h;

[0028] Optionally, the water includes the aqueous phase I separated in the distillation tower 1.

[0029] Optionally, in step S2, the mass ratio of 2,2-difluoroethyl acetate, difluoroethanol, and water in the overhead distillate is 78:3:19, presenting a ternary azeotropic state.

[0030] Optionally, in step S2, the aqueous phase I contains 92-94 wt% of water, and the rest are 2,2-difluoroethanol, 2,2-difluoroethyl acetate, and acetic acid in descending order of content.

[0031] Optionally, in step S2, the ester phase I contains 93.5-95.5 wt% of 2,2-difluoroethyl acetate, and the rest are 2,2-difluoroethanol, water, and acetic acid in descending order of content.

[0032] Optionally, in steps S1 and S2, the pre-reactor and the distillation tower 1 contain homogeneous and / or heterogeneous catalysts.

[0033] Optionally, the homogeneous catalyst is selected from B acid.

[0034] Optionally, the homogeneous catalyst is selected from at least one B acid selected from toluenesulfonic acid and concentrated sulfuric acid.

[0035] Optionally, the heterogeneous catalyst is selected from sulfonic acid resins.

[0036] Optionally, the mass ratio of the catalyst to 2,2-difluoroethanol is 0.01 to 0.05:1.

[0037] Optionally, the mass ratio of the catalyst to 2,2-difluoroethanol is 0.01 to 0.03:1.

[0038] Optionally, in step S3, the bottom liquid of the distillation tower 2 enters the distillation tower 3 for further distillation, the top temperature is 87-89° C., an organic phase rich in 2,2-difluoroethanol is extracted from the top of the tower, circulated into the distillation tower 1 for further reaction, and the bottom liquid is discharged for sewage treatment.

[0039] Optionally, in the distillation tower 3, the temperature of the bottom of the tower is raised to reflux at the top of the tower under normal pressure, and the top temperature gradually rises to 87-89°C.

[0040] Optionally, the organic phase rich in 2,2-difluoroethanol contains 67-69 wt % of 2,2-difluoroethanol and 30-32 wt % of water, with the remainder being 2,2-difluoroethyl acetate and acetic acid.

[0041] Optionally, the bottom liquid contains at least 99 wt % of water, with the remainder being 2,2-difluoroethyl acetate, 2,2-difluoroethanol, and acetic acid.

[0042] Optionally, in step S3, the extraction process conditions are: full reflux for 1 hour, then extraction from the top of the tower at a reflux ratio of 1 to 10:1, a top temperature of 82 to 84°C, a bottom temperature of 108°C to 110°C, and a top extraction rate of 55 to 60 mL / h.

[0043] Water, 2,2-difluoroethanol and 2,2-difluoroethyl acetate at the top of the tower present a ternary azeotropic state.

[0044] Optionally, in steps S2 and S3, the standing time is 1 to 10 minutes.

[0045] Optionally, in steps S2 and S3, the standing time is 1 to 3 minutes.

[0046] Optionally, in steps S2 and S3, 2,2-difluoroethyl acetate, difluoroethanol, and water in the overhead distillate form a ternary azeotrope.

[0047] Optionally, in step S4 , during the distillation and purification process in the distillation tower 4 , an organic phase rich in 2,2-difluoroethanol is extracted from the top of the tower and circulated into the distillation tower 1 .

[0048] Optionally, the alkaline washing and deacidification process includes deacidifying the crude 2,2-difluoroethyl acetate with a carbonate solution to obtain an ester phase III; the weight ratio of the carbonate to the crude 2,2-difluoroethyl acetate is 0.1 to 0.4:1.

[0049] Optionally, the weight ratio of the carbonate to the crude 2,2-difluoroethyl acetate is 0.2:1.

[0050] Optionally, the carbonate is selected from at least one of sodium carbonate and potassium carbonate.

[0051] During the alkaline washing and deacidification process of the crude 2,2-difluoroethyl acetate (ester phase I, ester phase II or a mixture of the two), more difluoroethanol dissolves in the alkaline water, resulting in less difluoroethanol in the crude 2,2-difluoroethyl acetate (ester phase III) after the alkaline washing and deacidification, thereby reducing the energy consumption for separating difluoroethanol and the target ester.

[0052] Optionally, the dehydrating material is selected from at least one of anhydrous magnesium sulfate, molecular sieves, and osmotic membranes.

[0053] Optionally, the weight ratio of the anhydrous magnesium sulfate to the ester phase III is 0.05 to 0.2:1.

[0054] Optionally, the weight ratio of the anhydrous magnesium sulfate to the ester phase III is 0.06 to 0.1:1.

[0055] Optionally, the weight ratio of the molecular sieve to the ester phase III is 0.18 to 0.3:1.

[0056] Optionally, the weight ratio of the molecular sieve to the ester phase III is 0.2 to 0.25:1.

[0057] Optionally, the water removal filtration speed of the molecular sieve is 5 to 20 mL / min.

[0058] Optionally, the water removal filtration speed of the molecular sieve is 8 to 12 mL / min.

[0059] Optionally, the anhydrous magnesium sulfate and molecular sieve are regenerated by rotary evaporation or hot nitrogen purging after being used for dehydration.

[0060] Optionally, the regeneration process further obtains an aqueous phase and an organic phase rich in acetic acid 2,2-difluoroethanol, wherein the aqueous phase is circulated into the distillation tower 2, and the organic phase rich in acetic acid 2,2-difluoroethanol is fed into the distillation tower 1 to continue the reaction.

[0061] Optionally, in step S4, the process conditions for the side extraction are: top extraction at a reflux ratio of 5 to 30:1, a top temperature of 101 to 103°C, a side extraction temperature of 103 to 105°C, a bottom temperature of 128 to 132°C, a top extraction rate of 5 to 25 mL / h, and a side extraction rate of 40 to 60 mL / h.

[0062] Optionally, in step S4, the reflux ratio of the side extraction is selected from any value of 5:1, 7.5:1, 10:1, 12.5:1, 15:1, 17.5:1, 20:1, 22.5:1, 25:1, 27.5:1, 30:1, or a range between any two values.

[0063] Optionally, in step S4, the reflux ratio of the side extraction is 15 to 30:1.

[0064] As a preferred embodiment, the process comprises the following steps:

[0065] S1, pre-reacting raw materials containing acetic acid and 2,2-difluoroethanol in a pre-reactor to obtain a liquid mixture;

[0066] S2, the liquid mixture obtained in step 1 and water enter the distillation tower 1 for catalytic reaction, and the overhead distillate is taken out and allowed to stand to separate into the aqueous phase I and the ester phase I;

[0067] The aqueous phase I is divided into a circulating part and a non-circulating part, and the circulating part is circulated into the distillation tower 1 to maintain the ternary azeotropic state;

[0068] S3, the non-circulated portion of the aqueous phase I in step S2 enters the distillation tower 2 for further distillation, and the overhead is extracted and statically separated to obtain aqueous phase II and ester phase II; the aqueous phase II is circulated into the distillation tower 2;

[0069] S4. After mixing the ester phase II obtained in step S3 with the ester phase I obtained in step S2, the mixture is subjected to alkali washing to remove acid and dehydration, and then enters the distillation tower 4 for distillation and purification, and electronic grade 2,2-difluoroethyl acetate is obtained by side sampling.

[0070] Optionally, step S2 further comprises continuously adding a raw material mixture of acetic acid and 2,2-difluoroethanol to the bottom of the tower at a molar ratio of 0.5 to 2:1 at a feeding rate of 40 to 60 mL / h.

[0071] In this application, unless otherwise specified, the data range given is selected from any value in the range and includes the endpoint value of the range.

[0072] In this application, normal pressure refers to 101.3 kPa.

[0073] Alternatively, the reaction principle of preparing 2,2-difluoroethyl acetate by catalysis of acetic acid and 2,2-difluoroethanol in the present application is as follows:

[0074]

[0075] The beneficial effects of this application include:

[0076] 1) The present application provides a process for synthesizing electronic-grade 2,2-difluoroethyl acetate, using acetic acid and 2,2-difluoroethanol as raw materials. During the synthetic distillation process, water, 2,2-difluoroethanol and 2,2-difluoroethyl acetate form a ternary azeotropic reaction, and the top of the tower can be quickly separated into a water layer and an ester layer. The ester layer content is as high as 95%, greatly reducing the separation cost.

[0077] 2) The process of the present application includes an alkaline washing and acid removal process, which does not produce waste acid, making the entire process more environmentally friendly. In addition, more difluoroethanol is dissolved in the alkaline water during the alkaline washing and acid removal process, which also reduces the energy consumption for separating difluoroethanol and the target ester.

[0078] 3) In the process of the present application, the synthetic distillation section dehydrates the obtained crude 2,2-difluoroethyl acetate, which greatly reduces energy consumption.

[0079] 4) In the process method of the present application, the operation process of repeated full reflux enrichment followed by rapid extraction at a small reflux ratio is adopted for the first time in the distillation and purification section, and light components such as 2,2-difluoroethanol and water are continuously extracted at the top of the distillation tower, and electronic grade 2,2-difluoroethyl acetate is obtained by extraction in the middle.

[0080] 5) In the process of the present application, the generated electronic-grade 2,2-difluoroethyl acetate product has a high purity of more than 99.99%, a moisture content of less than 20 ppm, and a continuous cycle yield of up to 98%.

[0081] 6) In the process of the present application, the materials can be basically recycled throughout the entire process, and a small amount of wastewater is generated, which greatly reduces the treatment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1Schematic diagram of an embodiment of the process of the present invention.

[0083] Figure 2 This is a schematic diagram of an embodiment of the process flow of the dehydration step in the process flow of the present invention. DETAILED DESCRIPTION

[0084] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0085] Unless otherwise specified, the raw materials and catalysts in the examples of this application were purchased from commercial sources. 4A molecular sieve comes from conventional commercial dehydrated molecular sieves.

[0086] The invention uses acetic acid and 2,2-difluoroethanol as raw materials, and obtains high-purity electronic-grade 2,2-difluoroethyl acetate product through processes such as synthetic distillation, ternary azeotropic product separation and by-product re-experimental circulation, alkali washing, dehydration, distillation purification, etc.

[0087] The specific process of the present invention is:

[0088] like Figure 1 As shown, the raw materials acetic acid and 2,2-difluoroethanol are first pre-reacted in a pre-reactor to obtain a liquid mixture. The pre-reacted liquid mixture is continuously and stably fed to the distillation tower 1, and water is added to the distillation tower 1 at the same time. The reaction is continued in the atmospheric distillation tower I filled with a homogeneous or heterogeneous catalyst. The distillate is first fully refluxed and then the distillate is taken out from the top of the tower according to a fixed reflux ratio and the raw materials are continuously added to the bottom of the tower. After stabilization, the temperature of the top of the distillation tower is 82-84°C, and the temperature of the bottom of the tower is 108-110°C. The distillate taken out from the top of the tower presents a ternary azeotropic state. The top distillate is allowed to stand and separate to obtain an aqueous phase I and a phase rich in 2,2-difluoroethyl acetate. Ester phase I, of which aqueous phase I is partially recycled back to distillation column 1 to maintain ternary azeotropy, while the remaining portion enters distillation column 2 to separate aqueous phase II and ester phase II rich in 2,2-difluoroethyl acetate. Aqueous phase II is refluxed back into distillation column 2 for recycling. The ester phase mixture (crude 2,2-difluoroethyl acetate) of ester phase II rich in 2,2-difluoroethyl acetate and ester phase I rich in 2,2-difluoroethyl acetate is treated with carbonate to remove acetic acid, and then dehydrated using anhydrous magnesium sulfate, a permeable membrane, or a 4A molecular sieve. The deacidified and dehydrated ester phase mixture enters distillation column 4 for distillation and purification. The 2,2-difluoroethanol-rich organic phase is withdrawn from the top of the column, and electronic-grade 2,2-difluoroethyl acetate is obtained from the side. The bottom liquid in the distillation tower 2 is transferred to the distillation tower 3 for further distillation to obtain an organic phase rich in 2,2-difluoroethanol, which is circulated together with the organic phase rich in 2,2-difluoroethanol taken out from the top of the distillation tower 4 and returned to the distillation tower 1 to continue the reaction.

[0089] like Figure 2As shown, in the process of dehydration using anhydrous magnesium sulfate, a permeable membrane or a 4A molecular sieve, the anhydrous magnesium sulfate and the 4A molecular sieve after absorbing water are regenerated to obtain an aqueous phase and an organic phase rich in 2,2-difluoroethanol, wherein the organic phase rich in 2,2-difluoroethanol is used as a raw material to enter the distillation tower 1 for further reaction, and the aqueous phase is combined with the aqueous phase II separated by synthetic distillation in the distillation tower 2 and then enters the distillation tower 2 for further distillation.

[0090] Example 1

[0091] like Figure 1 As shown, 768.09 g of acetic acid and 1049.62 g of 2,2-difluoroethanol were added to a 2 L autoclave reactor. After connecting a cooling reflux device, the reactor was heated to 80 ° C. and kept warm for 4 hours. After sampling and detection, the product composition was 63.66 wt% of 2,2-difluoroethyl acetate, 15.65 wt% of 2,2-difluoroethanol, 11.45 wt% of acetic acid, and 9.24 wt% of water.

[0092] Example 2

[0093] like Figure 1 As shown, the raw materials acetic acid and 2,2-difluoroethanol (946.61 g of acetic acid and 657.73 g of 2,2-difluoroethanol) were first pre-reacted in a pre-reactor to obtain a liquid mixture, and the reaction temperature was 130°C. The pre-reacted liquid mixture was continuously and stably fed to the distillation tower 1, and 103 g of water was added to the distillation tower 1. The reaction was continued in the atmospheric distillation tower 1 filled with 19.8 g of p-toluenesulfonic acid catalyst, and the distillate was steadily withdrawn from the top of the tower at a reflux ratio of 3:1. At the same time, the raw materials were continuously added to the bottom of the tower at a molar ratio of acetic acid, 2,2-difluoroethanol, and water of 10:10:7 at a feeding rate of 50 mL / h. After stabilization, the temperature of the top of the distillation tower is 82-84° C., the temperature of the bottom of the tower is 109° C., and distillate is produced from the top of the tower at a rate of 50 mL / h. The mass ratio of 2,2-difluoroethyl acetate, difluoroethanol, and water in the top distillate is maintained at a constant 78:3:19, presenting a ternary azeotropic state. The top distillate is allowed to stand and separate to obtain an aqueous phase I and an ester phase I rich in 2,2-difluoroethyl acetate; wherein the composition of the aqueous phase I is 92.38 wt% of water, 2.41 wt% of 2,2-difluoroethyl acetate, 4.54 wt% of 2,2-difluoroethanol, and 0.67 wt% of acetic acid; and the composition of the ester phase I is 1.85 wt% of water, 94.57 wt% of 2,2-difluoroethyl acetate, 3.54 wt% of 2,2-difluoroethanol, and 0.01 wt% of acetic acid.

[0094] During the entire reaction distillation process, 1661.02 g of acetic acid and 1633.87 g of 2,2-difluoroethanol were added to obtain 2347.73 g of 2,2-difluoroethyl acetate.

[0095] Example 3

[0096] The raw materials and process conditions were the same as those in Example 2, except that concentrated sulfuric acid was used as the catalyst. A total of 1639.21 g of acetic acid and 1580.03 g of 2,2-difluoroethanol were added during the entire reaction and distillation process to obtain 2271.48 g of 2,2-difluoroethyl acetate.

[0097] Example 4

[0098] The raw materials were acetic acid and 2,2-difluoroethanol (968.21 g of acetic acid and 663.02 g of 2,2-difluoroethanol), 19.9 g of strongly acidic cation exchange resin was used as the catalyst, and the other process conditions were the same as those in Example 2. A total of 1662.35 g of acetic acid and 1587.18 g of 2,2-difluoroethanol were added during the entire reaction and distillation process to obtain 2277.31 g of 2,2-difluoroethyl acetate.

[0099] Example 5

[0100] The raw materials and process conditions were the same as those in Example 4, except that the strongly acidic cation exchange resin was mixed with the distillation tower filler and loaded. A total of 1593.88 g of acetic acid and 1531.51 g of 2,2-difluoroethanol were added during the entire reactive distillation process to obtain 2137.20 g of 2,2-difluoroethyl acetate.

[0101] Example 6

[0102] The process conditions were the same as in Example 2, except that the raw materials were acetic acid and 2,2-difluoroethanol (937.24 g acetic acid and 644.97 g 2,2-difluoroethanol), 19.7 g p-toluenesulfonic acid was used as the catalyst, and the raw materials were continuously added to the reactor in a molar ratio of acetic acid to 2,2-difluoroethanol of 1:1. As the overhead distillate was withdrawn, the tower top temperature gradually increased to 83-86°C, and the tower top withdrawal rate was as low as 15 mL / h. Then, 2,2-difluoroethanol and water were added to the reactor in a molar ratio of 10:7 (here, the water was the aqueous phase obtained by standing and separating the overhead distillate of rectifying tower 1, which was circulated into rectifying tower 1 to maintain the ternary azeotropic reaction). The total feed rate was 50 mL / h, the tower top temperature was maintained at 82-84°C, and the withdrawal rate was maintained at 50 mL / h.

[0103] Example 7

[0104] 1678.96 g of the aqueous phase I obtained by separating the distillate from the top of the distillation tower 1 in Example 6 was taken and distilled into the distillation tower 2 for rectification. The distillate was heated to boiling at room temperature and reflux occurred at the top of the tower. The distillate was stably withdrawn from the top of the tower at a reflux ratio of 3:1. When the top temperature of the distillation tower 2 was 82-84 ° C, water, 2,2-difluoroethanol and 2,2-difluoroethyl acetate were azeotroped in the ternary system. The distillate from the top of the tower was allowed to stand and separate to obtain 14.61 g of aqueous phase II and 51 .08g of ester phase II rich in 2,2-difluoroethyl acetate, wherein the composition of aqueous phase II is 92.21wt% of water, 2,2-difluoroethyl acetate 2.71wt%, 2,2-difluoroethanol 4.41wt%, and acetic acid 0.67wt%; the composition of ester phase II is 1.98wt% of water, 94.17wt% of 2,2-difluoroethyl acetate, 3.65wt% of 2,2-difluoroethanol, and 0.01wt% of acetic acid.

[0105] The bottom liquid in 1602.54g of distillation tower 2 is transferred to distillation tower 3 for further distillation. The bottom liquid is heated to reflux at the top of the tower under normal pressure. The top temperature is gradually increased to 88°C. The top is sampled with an organic phase rich in 2,2-difluoroethanol (main components are 2,2-difluoroethanol and water). The top temperature is further increased to 95-98°C. The main component of the top is water, and the distillation is stopped at this time. 103.71g of an organic phase rich in 2,2-difluoroethanol is obtained at the top of the tower, which is composed of 0.04wt% of 2,2-difluoroethyl acetate, 68.25wt% of 2,2-difluoroethanol, 0.00wt% of acetic acid, and 31.09wt% of water. It is circulated into distillation tower 1 to continue the reaction. At this time, the bottom composition is 0.00wt% of 2,2-difluoroethyl acetate, 0.03wt% of 2,2-difluoroethanol, 0.01wt% of acetic acid, and 99.86wt% of water. The bottom is treated with sewage.

[0106] Example 8

[0107] Place 140 g of saturated sodium carbonate solution and 1215.89 g of crude 2,2-difluoroethyl acetate obtained by synthetic distillation (ester phase I, ester phase II, or a mixture thereof; the components and proportions before and after acid removal are shown in Table 1) in a separatory funnel. Stir and mix at room temperature for 5 minutes. After 5 minutes of stabilization, the mixture separates into an ester layer and an aqueous layer. The mass of the 2,2-difluoroethyl acetate remains essentially unchanged, while the acetic acid content is significantly reduced from 55 ppm to below 1 ppm. Dispose of the waste alkali solution.

[0108] Table 1 Comparison of components and proportions of crude 2,2-difluoroethyl acetate before and after deacidification

[0109]

[0110] Example 9

[0111] Take 2296.07g of crude 2,2-difluoroethyl acetate (such as Figure 1 To the ester phase III shown in FIG2 , 300 g of anhydrous magnesium sulfate was added, stirred for 5 minutes, allowed to stand for 4 hours, and then filtered using filter paper. The moisture content of the solution decreased from 20,400 ppm to 3,900 ppm. A comparison of the components and proportions before and after dehydration is shown in Table 2. Multiple dehydration cycles using magnesium sulfate can also reduce the moisture content to less than 200 ppm, but this results in a greater loss of the organic phase.

[0112] Table 2 Comparison of components and proportions before and after dehydration using anhydrous magnesium sulfate

[0113]

[0114] Take 403.11g of anhydrous magnesium sulfate after absorbing water, such as Figure 2 As shown, it was regenerated using a rotary evaporator with the temperature set to 80°C and the vacuum set to -85 kPa. The rotary evaporation condensate was allowed to stand and separate into 366.21 g of ester layer and 34.48 g of water layer. The components and proportions are shown in Table 3. The water layer was combined with the aqueous phase I of the synthetic distillation and then entered distillation tower 2 for further distillation. The ester layer was used as a raw material and entered distillation tower 1 for further reaction.

[0115] Table 3 Components and proportions of anhydrous magnesium sulfate regeneration after water absorption

[0116]

[0117] Example 10

[0118] Take 372.21g 4A molecular sieves and fill them into a transparent glass column with a diameter of 4cm. The filling height is about 50cm. Use a high-pressure metering pump to add 2603.14g crude 2,2-difluoroethyl acetate (such as Figure 1 The ester phase (shown as Phase III) was passed through molecular sieves above the glass column at a flow rate of 10 mL / min. After dehydration of the crude product, 295 g of fresh 4A molecular sieves were replaced and the process repeated. After dehydration, the moisture content of the crude 2,2-difluoroethyl acetate was significantly reduced from 18,700 ppm to 68 ppm. Table 4 shows a comparison of the components and proportions before and after dehydration. The 4A molecular sieves gained 152.55 g.

[0119] Table 4 Comparison of components and proportions before and after dehydration using 4A molecular sieve

[0120]

[0121] like Figure 2As shown, the 4A molecular sieve after water absorption was regenerated using a rotary evaporator with the temperature set to 80°C and the vacuum set to -85 kPa. The rotary evaporation condensate was allowed to stand and separate into 117.3 g of ester layer and 40.98 g of water layer. The components and proportions are shown in Table 5. The water layer was combined with the aqueous phase I of the synthetic distillation and then entered the distillation column 2 for further distillation. The ester layer was used as a raw material and entered the distillation column 1 for further reaction.

[0122] Table 5 Components and proportions of 4A molecular sieve regeneration after water absorption

[0123]

[0124] Example 11

[0125] 1875.62 g of crude 2,2-difluoroethyl acetate (such as Figure 1 Ester phase III) as shown, Figure 2 As shown, dehydration was performed using a permeable membrane. A vacuum pump was used on the other side of the membrane to increase the osmotic force of the water. After three cycles of dehydration, the moisture content was reduced from 21,500 ppm to 1,130 ppm. A comparison of the components and proportions before and after dehydration is shown in Table 6.

[0126] Table 6 Comparison of components and proportions before and after dehydration using osmotic membrane

[0127]

[0128] Example 12

[0129] Build a 2m distillation device (such as Figure 1 The distillation column 4 shown in the figure is provided with a side sampling at a height of 0.5 m and a continuous feed port at a height of 1.5 m, which is filled with stainless steel triangular spiral ring packing. 1587.43 g of dehydrated crude 2,2-difluoroethyl acetate (such as Figure 1 The resulting ester phase IV (shown as ester phase IV) contained 96.34 wt% 2,2-difluoroethyl acetate, 3.05 wt% 2,2-difluoroethanol, 0.0003 wt% acetic acid, and 149 ppm water. The column bottom was heated to 130°C under atmospheric pressure, with a reflux ratio of 30:1. The purity of the side-drawn 2,2-difluoroethyl acetate was monitored. Stable withdrawal began when the side-drawn 2,2-difluoroethyl acetate content exceeded 99.99%. At this point, the column top temperature was 101°C-103°C, and the side-draw temperature was 103-105°C. The unqualified product component obtained from the top draw (the organic phase rich in 2,2-difluoroethanol) was transferred to distillation column 1 for further reaction. After distillation, the bottom color of the column bottom was light yellow and slightly viscous, with a 2,2-difluoroethyl acetate content of 99.98% and an acetic acid content of 0.0135%. The components and ratios of the continuously withdrawn components from the top are shown in Table 7.

[0130] Table 7 Comparison of components and proportions before and after dehydration using osmotic membrane

[0131] 2,2-Difluoroethyl acetate (%) 2,2-Difluoroethanol (%) Acetic acid (%) Moisture (ppm) Side Picking 1 99.1977 0.7818 0.0000 764 Side Pick 2 99.8660 0.1086 0.0000 212 Side Pick 3 99.8885 0.0859 0.0000 199 Side Picking 4 99.9517 0.0167 0.0000 32 Side Picking 5 99.9893 0.0077 0.0000 24 Side Picking 6 99.9901 0.0064 0.0000 12 Side Pick 7 99.9926 0.0053 0.0000 3 Tower Kettle 99.8435 0.0049 0.0135 6

[0132] Example 13

[0133] Build a 2m distillation device (such as Figure 1 The distillation column 4 is shown in the figure. A mid-range feed is added at a height of 0.5 m in the distillation column and a continuous feed port is added at a height of 1.5 m. The distillation column is filled with a stainless steel triangular spiral ring packing. 1611.48 g of dehydrated crude 2,2-difluoroethyl acetate (such as Figure 1 The ester phase IV shown in the figure contains 97.14 wt% 2,2-difluoroethyl acetate, 2.82 wt% 2,2-difluoroethanol, 0.0002 wt% acetic acid, and 152 ppm water. The bottom of the tower was heated to 130°C under normal pressure, and after full reflux for 1 hour, crude 2,2-difluoroethyl acetate with the same components was continuously introduced. The reflux ratios of 5:1, 10:1, 15:1, 20:1, 25:1, and 30:1 were set, respectively, to be extracted from the top of the tower, with corresponding feed rates of 80, 70, 65, 63, 58, and 55 mL / min; the side extraction rate was 50 mL / h. After the composition of the top and side extraction organic phases stabilized, their composition was analyzed. The results are shown in Tables 8 and 9. It can be seen that as the reflux ratio increases, the content of difluoroethanol at the top of the tower increases, and the purity of the side extraction product is improved.

[0134] Table 8 Relationship between top extraction velocity, organic phase composition and reflux ratio

[0135]

[0136] Table 9 Relationship between side-sampling organic phase composition and reflux ratio

[0137] Reflux ratio 2,2-Difluoroethyl acetate (%) 2,2-Difluoroethanol (%) Acetic acid (%) Moisture (ppm) 5:1 99.8905 0.0977 0 43 10:1 99.9391 0.0539 0 25 15:1 99.9811 0.0151 0 21 20:1 99.9883 0.0097 0 12 25:1 99.9907 0.0089 0 3 30:1 99.9921 0.0072 0 3

[0138] Example 14

[0139] The raw materials, acetic acid and 2,2-2,2-difluoroethanol (946.61 g acetic acid and 657.73 g 2,2-2,2-difluoroethanol), were first pre-reacted in a pre-reactor to obtain a liquid mixture at a reaction temperature of 130°C. The pre-reacted liquid mixture was continuously and stably fed to distillation column 1. Simultaneously, 103 g of water was added to distillation column 1. The reaction continued in atmospheric distillation column 1 filled with 19.8 g of p-toluenesulfonic acid catalyst. The mixture was fully refluxed for 1 hour, and then a distillate was steadily withdrawn from the top of the column at a reflux ratio of 3:1. Simultaneously, the raw materials were continuously added to the bottom of the column at a molar ratio of acetic acid, 2,2-difluoroethanol, and water of 10:10:7 at a feeding rate of 50 mL / h. The overhead distillate ester phase I is deacidified with anhydrous sodium carbonate and dehydrated with molecular sieves before entering distillation tower 4 for rectification and purification (process conditions are the same as in Examples 8 and 10); a portion of the aqueous phase I enters distillation tower 1 to maintain ternary azeotropy, and the other portion enters distillation tower 2 and distillation tower 3 to recover aqueous phase II, ester phase II, and 2,2-difluoroethanol-rich organic phase. The aqueous phase II is circulated into distillation tower 2, the ester phase II is combined with the ester phase I, and the 2,2-difluoroethanol-rich organic phase is returned to distillation tower 1 for further distillation. The process conditions in distillation towers 2 and 3 are the same as in Example 7. The 4A molecular sieve after water absorption is rotary evaporated, and the obtained aqueous phase III is circulated into distillation tower 2, and the 2,2-difluoroethanol-rich organic phase is returned to distillation tower 1 for further distillation. The feed was continuously added for 360 hours until all the materials were basically circulated and reacted. A total of 7687.16 g of acetic acid and 9858.95 g of 2,2-difluoroethanol were added. 485.7 g of the residual liquid in the first kettle of the distillation tower, of which 89.56 wt% of 2,2-difluoroethyl acetate, 2.47 wt% of 2,2-difluoroethanol, 1.44 wt% of acetic acid, and 6.53 wt% of water were added; 279.64 g of the residual liquid in the fourth kettle of the distillation tower, of which 99.83 wt% of 2,2-difluoroethyl acetate, 0.0038 wt% of 2,2-difluoroethanol, 0.0117 wt% of acetic acid, and 0.0004 wt% of water were added. A total of 14640.27 g of electronic grade 2,2-difluoroethyl acetate was obtained, with a total yield of 98.21%.

[0140] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A process for synthesizing electronic grade 2,2-difluoroethyl acetate, characterized in that: The process steps include: S1, pre-reacting raw materials containing acetic acid and 2,2-difluoroethanol in a pre-reactor to obtain a liquid mixture; S2, the liquid mixture obtained in step S1 and water enter the distillation tower 1 for catalytic reaction, and the overhead distillate is collected and allowed to stand to separate into the aqueous phase I and the ester phase I; S3, the aqueous phase I obtained in step S2 enters the distillation tower 2 for further distillation, and the top of the tower is extracted and statically separated to obtain the aqueous phase II and the ester phase II; The aqueous phase II circulates into the distillation tower 2; S4, the crude 2,2-difluoroethyl acetate is subjected to alkali washing to remove acid and dehydrate, and then enters the distillation tower 4 for distillation and purification, and electronic grade 2,2-difluoroethyl acetate is obtained by side sampling; The crude 2,2-difluoroethyl acetate is the ester phase II obtained in step S3, the ester phase I obtained in step S2, or a mixture of the two; In the steps S1 and S2, the pre-reactor and the distillation column 1 contain homogeneous and / or heterogeneous catalysts; In step S2, the extraction process conditions are: total reflux for 0.5 to 3 hours, followed by extraction from the top of the tower at a reflux ratio of 1 to 10:1, a top temperature of 82 to 84°C, a bottom temperature of 108 to 110°C, and a top extraction rate of 50 to 60 mL / h; In the steps S2 and S3, 2,2-difluoroethyl acetate, difluoroethanol, and water in the overhead distillate form a ternary azeotrope; In step S3, the bottom liquid of the distillation tower 2 enters the distillation tower 3 for further distillation, and the top temperature is 87-89°C. The organic phase rich in 2,2-difluoroethanol is extracted from the top of the tower and circulated into the distillation tower 1 to continue the reaction, and the bottom liquid is discharged for sewage treatment; In step S4, during the distillation and purification process of the distillation tower 4, an organic phase rich in 2,2-difluoroethanol is extracted from the top of the tower and circulated into the distillation tower 1; In step S4, the process conditions for the side extraction are: extraction from the top of the tower at a reflux ratio of 25 to 30:1, a top temperature of 101 to 103°C, a side extraction temperature of 103 to 105°C, a bottom temperature of 128 to 132°C, a top extraction rate of 5 to 25 mL / h, and a side extraction rate of 40 to 60 mL / h.

2. The process according to claim 1, characterized in that: In the step S1, the feed molar ratio of acetic acid to 2,2-difluoroethanol is 1 to 3:

1.

3. The process according to claim 1, characterized in that: In step S1, the reaction temperature of the pre-reactor is 50-100° C., and the reaction time is 0.5-10 h.

4. The process according to claim 1, characterized in that: The pre-reactor is a fixed bed reactor or a tank reactor.

5. The process according to claim 1, characterized in that: The homogeneous catalyst is selected from B acid.

6. The process according to claim 1, characterized in that: The heterogeneous catalyst is selected from sulfonic acid resins.

7. The process according to claim 1, characterized in that: In steps S2 and S3, the standing time is 1 to 10 minutes.

8. The process according to claim 1, characterized in that: In the step S2, the molar ratio of the water to the 2,2-difluoroethanol in the step S1 is 0.5 to 3:

1.

9. The process according to claim 1, characterized in that: The step S2 further includes continuously adding a raw material mixture of acetic acid, 2,2-difluoroethanol, and water to the bottom of the tower in a molar ratio of 5-10:5-10:7 at a feeding rate of 30-300 mL / h.

10. The process according to claim 9, characterized in that: The water includes the aqueous phase I separated in the distillation tower 1.

11. The process according to claim 1, characterized in that: In step S2, the aqueous phase I contains 92-94 wt% of water, and the rest of the components are 2,2-difluoroethanol, 2,2-difluoroethyl acetate, and acetic acid in descending order of content.

12. The process according to claim 1, characterized in that: In the step S2, the ester phase I contains 93.5-95.5 wt% of 2,2-difluoroethyl acetate, and the rest are 2,2-difluoroethanol, water, and acetic acid in descending order of content.

13. The process according to claim 1, characterized in that: The alkaline washing and deacidification process comprises deacidifying the crude 2,2-difluoroethyl acetate through a carbonate solution to obtain an ester phase III; The weight ratio of the carbonate to the crude 2,2-difluoroethyl acetate is 0.1-0.4:

1.

14. The process according to claim 13, characterized in that: The carbonate is selected from at least one of sodium carbonate and potassium carbonate.

15. The process according to claim 1, characterized in that: In step S4, the dehydrating material is selected from at least one of anhydrous magnesium sulfate, molecular sieve, and permeable membrane.

16. The process according to claim 15, characterized in that: The weight ratio of the anhydrous magnesium sulfate to the ester phase III is 0.05 to 0.2:

1.

17. The process according to claim 15, characterized in that: The weight ratio of the molecular sieve to the ester phase III is 0.18 to 0.3:1.

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