CN115872863A

CN115872863A - Process method for synthesizing electronic grade 2, 2-difluoroethyl acetate

Info

Publication number: CN115872863A
Application number: CN202211565993.8A
Authority: CN
Inventors: 侯家祥; 石磊; 范兴家; 阎子祯; 牛磊磊; 刘佩; 李光科
Original assignee: Shenyang University of Chemical Technology; Shinghwa Advanced Material Group Co Ltd; Shenghua New Energy Technology Dongying Co Ltd
Current assignee: Shenyang University of Chemical Technology; Shinghwa Advanced Material Group Co Ltd; Shenghua New Energy Technology Dongying Co Ltd
Priority date: 2022-12-07
Filing date: 2022-12-07
Publication date: 2023-03-31

Abstract

The application discloses a process method for synthesizing electronic grade 2, 2-difluoroethyl acetate, which comprises the following process steps: s1, pre-reacting a raw material containing acetic acid and 2, 2-difluoroethanol in a pre-reactor to obtain a liquid mixture; s2, allowing the liquid mixture and water to enter a rectifying tower 1 for catalytic reaction, collecting a tower top distillate, and standing to separate a water phase I and an ester phase I; s3, the water phase I enters a rectifying tower 2 for further rectification, and a water phase II and an ester phase II are obtained through tower top extraction, standing and separation; the water phase II circularly enters a rectifying tower 2; and S4, performing alkali washing on the ester phase obtained in the steps S2 and S3 to remove acid, dehydrating, then, entering a rectifying tower 4 for rectification and purification, and laterally collecting to obtain the electronic grade 2, 2-difluoroethyl acetate. The process method has the advantages of high product purity, small water content, high separation speed, low energy consumption and no waste acid, materials can be basically and completely recycled, only a small amount of waste water is generated, and the whole process is more environment-friendly.

Description

Process method for synthesizing electronic grade 2, 2-difluoroethyl acetate

Technical Field

The application relates to a process method for synthesizing electronic grade 2, 2-difluoroethyl acetate, belonging to the field of battery electrolyte additive methods.

Background

Along with research and development of portable electronic equipment and new energy automobiles, the demand of the lithium ion battery as a high energy density battery is greatly increased, the electrolyte serving as one of three elements of the lithium ion battery accounts for 20-30% of the cost of the raw materials of the whole battery, is a key factor influencing the performance of the lithium ion battery, has excellent active development performance, has great practical significance for an electrolyte system with low price, and can further reduce the industrial cost of the lithium ion battery and improve the market competitiveness.

The electrolyte not only determines Li ⁺ The migration rate in the liquid phase, which also participates in the formation of the SEI film, plays a critical role in the SEI film performance. The viscosity of the electrolyte is increased at low temperature, the conductivity is reduced, the SEI film impedance is increased, the compatibility with positive and negative electrode materials is poor, and the battery performance is greatly improvedEnergy density, cycle performance, etc. Fluoro-solvents are a viable solution to many lithium battery problems. Fluorinated organic solvents have unique physicochemical properties due to the very high electronegativity and low polarizability of the fluorine atoms. The fluoro solvent can be used as an additive to form a solid electrolyte interface rich in LiF, and an SEI layer formed by induction is compact and stable, so that a uniform Li deposition form is obtained. 2, 2-difluoroethyl acetate is used as an important component of a fluoro solvent, so that the high-temperature, normal-temperature and low-temperature cycle performance of the battery can be greatly improved, and the low-temperature storage performance is greatly improved.

The synthesis method and the process of the currently disclosed 2, 2-difluoroethyl acetate are few, for example, the acylation method used in patent CN113698295A not only generates waste acid, but also has low productivity and relatively poor purity, and can not realize later-stage industrialization. The same type of product, methyl difluoroacetate, is currently disclosed: JP6228043 hydrolyzes N, N-diethyl difluoroacetamide with potassium hydroxide to give difluoroacetic acid, which is esterified with methanol to give methyl difluoroacetate; patent CN102531895A discloses a method for preparing methyl difluoroacetate by fluorination reaction of methyl dichloroacetate and potassium fluoride as catalyst at high temperature, adding organic solvent, cooling the system to below 0 ℃, keeping the temperature, reducing pressure, steaming, and filtering. Patent CN114085151A discloses a preparation method of high-purity ethyl difluoroacetate, which comprises the steps of taking difluoroacetyldialkylamine and ethanol as raw materials, taking concentrated sulfuric acid as a catalyst, carrying out esterification reaction to obtain a crude product of the ethyl difluoroacetate, and then carrying out distillation and rectification to obtain the high-purity ethyl difluoroacetate, wherein the purity value is more than 99 percent and the water content is less than 500 ppm; patent CN103864615A discloses a process for preparing ethyl trifluoroacetate by a continuous non-catalytic method, wherein ethyl trifluoroacetate is produced by reacting and rectifying trifluoroacetyl chloride and ethanol, but the purity can only reach 99%, and acid-containing wastewater is generated. In patent CN104710308A, trifluoroacetic acid and ethanol are used as raw materials, strong acid cation exchange resin is used as catalyst, at 40-50 ℃ and normal pressure, ethanol is dropped and kept for 20 minutes, heating and refluxing are carried out to separate out the mixture of water and ethanol to make the reaction complete, after the crude product is washed with water to remove excessive ethanol, layering is carried out to obtain qualified product ethyl trifluoroacetate with content of more than 99.5% and moisture of less than 0.1%. Patent CN110343043A discloses a purification process of ethyl trifluoroacetate, which comprises washing crude ethyl trifluoroacetate with distilled water to remove most of alcohol and a small amount of acid contained in the crude ethyl trifluoroacetate; and adsorbing the washed ethyl trifluoroacetate crude product by using a molecular sieve adsorbent, and finally rectifying the ethyl trifluoroacetate crude product to obtain the high-purity ethyl trifluoroacetate, wherein the purity of the high-purity ethyl trifluoroacetate is over 99.9 percent, and the water content and the acidity content of the high-purity ethyl trifluoroacetate are respectively lower than 5ppm and 10ppm.

At present, the research field of the synthesis and purification method of the 2, 2-difluoroethyl acetate is blank, and the obtained product has low purity and poor industrial application, so that the development of a process route which has low energy consumption, high atom economy, high purity of the obtained 2, 2-difluoroethyl acetate product and can realize continuous reaction has important economic and social significance.

Disclosure of Invention

According to one aspect of the application, a process method for synthesizing electronic grade 2, 2-difluoroethyl acetate is provided, and the process takes acetic acid and 2, 2-difluoroethanol as raw materials, and obtains a high-purity electronic grade 2, 2-difluoroethyl acetate product through processes of synthetic rectification, product separation and by-product re-reaction circulation, alkali washing, dehydration, rectification purification and the like.

The technical scheme is as follows:

a process method for synthesizing electronic grade 2, 2-difluoroethyl acetate comprises the following process steps:

s1, pre-reacting a raw material containing acetic acid and 2, 2-difluoroethanol in a pre-reactor to obtain a liquid mixture;

s2, allowing the liquid mixture obtained in the step S1 and water to enter a rectifying tower 1 for catalytic reaction, collecting a tower top distillate, and standing to separate a water phase I and an ester phase I;

s3, the water phase I obtained in the step S2 enters a rectifying tower 2 for further rectification, and a water phase II and an ester phase II are obtained through tower top extraction, standing and separation; the water phase II circularly enters a rectifying tower 2;

s4, performing alkali washing on the crude product of the 2, 2-difluoroethyl acetate to remove acid, dehydrating, then, entering a rectifying tower 4 for rectification and purification, and performing side mining to obtain the electronic grade 2, 2-difluoroethyl acetate;

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

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

Alternatively, the feed molar ratio of the acetic acid and the 2, 2-difluoroethanol in the step S1 is 0.5 to 3.

Alternatively, the feed molar ratio of the acetic acid and the 2, 2-difluoroethanol in the step S1 is 1 to 3.

Alternatively, the feed molar ratio of the acetic acid and 2, 2-difluoroethanol in step S1 is selected from any value of 1.

Optionally, in the step S1, the reaction temperature of the pre-reactor is 50 to 100 ℃, and the reaction time is 0.5 to 10 hours.

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

Alternatively, the molar ratio of the water to the 2, 2-difluoroethanol in the step S1 is 0.5 to 3.

Alternatively, the molar ratio of the water to the 2, 2-difluoroethanol in step S1 is selected from any of 0.5.

Optionally, in step S2, the extraction process conditions are: carrying out total reflux for 0.5-3 h, then carrying out tower top extraction at the reflux ratio of 1-10;

alternatively, the reflux ratio is selected from any of 1, 3;

optionally, in step S2, the extraction process conditions are: and carrying out total reflux for 0.5-1 h, then carrying out top extraction at the reflux ratio of 1-3.

Alternatively, the reflux ratio is selected from any of 1, 1.5.

Optionally, in the step S2, a raw material mixture of acetic acid, 2-difluoroethanol and water is continuously supplemented into the column reactor according to a molar ratio of 5-10;

optionally, the feed rate is 30 to 120mL/h;

alternatively, the water comprises the aqueous phase I separated in the rectification column 1.

Optionally, in the step S2, the mass ratio of 2, 2-difluoroethyl acetate, difluoroethanol and water in the overhead distillate is 78.

Optionally, in the step S2, the water phase I comprises 92-94 wt% of water, and the rest are 2, 2-difluoroethanol, 2-difluoroethyl acetate and acetic acid in sequence from high to low.

Optionally, in the step S2, the ester phase I contains 93.5 to 95.5wt% of 2, 2-difluoroethyl acetate, and the rest are 2, 2-difluoroethanol, water and acetic acid in sequence from high to low.

Alternatively, in said steps S1 and S2, the prereactor and rectification column 1 comprise a homogeneous and/or heterogeneous catalyst.

Alternatively, the homogeneous catalyst is selected from a B acid.

Optionally, the homogeneous catalyst is selected from at least one of a group consisting of toluenesulfonic acid, concentrated sulfuric acid, and a Bronsted sulfuric acid.

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

Optionally, the mass ratio of the catalyst to 2, 2-difluoroethanol is from 0.01 to 0.05.

Optionally, the mass ratio of the catalyst to the 2, 2-difluoroethanol is 0.01 to 0.03.

Optionally, in the step S3, the tower bottoms of the rectifying tower 2 enter the rectifying tower 3 for further rectification, the tower top temperature is 87-89 ℃, an organic phase rich in 2, 2-difluoroethanol is obtained at the tower top, and the organic phase is circulated to enter the rectifying tower 1 for continuous reaction, and the tower bottoms are subjected to pollution discharge treatment.

Optionally, in the rectifying tower 3, the temperature of the tower kettle is raised to the reflux at the top of the tower under normal pressure, and the top temperature is gradually raised to 87-89 ℃.

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

Optionally, the bottoms contains at least 99wt% water, the remainder being 2, 2-difluoroethyl acetate, 2-difluoroethanol, acetic acid.

Optionally, in step S3, the extraction process conditions are: and carrying out total reflux for 1h, then carrying out tower top extraction at the reflux ratio of 1-10.

The water, 2-difluoroethanol and 2, 2-difluoroethyl acetate at the tower top are in a ternary azeotropic state.

Optionally, in the steps S2 and S3, the standing time is 1 to 10min.

Optionally, in the steps S2 and S3, the standing time is 1 to 3min.

Alternatively, in steps S2 and S3, the 2, 2-difluoroethyl acetate, difluoroethanol, and water in the overhead form a ternary azeotrope.

Optionally, in the step S4, in the process of rectifying and purifying in the rectifying tower 4, an organic phase rich in 2, 2-difluoroethanol is extracted from the top of the tower and is recycled to the rectifying tower 1.

Optionally, the alkali washing acid removal process comprises removing acid from the crude 2, 2-difluoroethyl acetate by 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.

Alternatively, the weight ratio of the carbonate to the crude 2, 2-difluoroethyl acetate is 0.2.

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

In the process of alkali washing acid removal of the 2, 2-difluoroethyl acetate crude product (ester phase I, ester phase II or the mixture of the ester phase I and the ester phase II), more difluoroethanol is dissolved in alkali water, so that difluoroethanol in the 2, 2-difluoroethyl acetate crude product (ester phase III) after the acid removal by alkali washing is less, and the energy consumption for separating the difluoroethanol from the target ester is reduced.

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

Optionally, the weight ratio of the anhydrous magnesium sulfate to the ester phase III is 0.05 to 0.2.

Optionally, the weight ratio of the anhydrous magnesium sulfate to the ester phase III is 0.06-0.1.

Optionally, the weight ratio of the molecular sieve to the ester phase III is from 0.18 to 0.3.

Optionally, the weight ratio of the molecular sieve to the ester phase III is from 0.2 to 0.25.

Optionally, the molecular sieve has a water removal filtration rate of 5 to 20mL/min.

Optionally, the molecular sieve has a water removal filtration rate of 8 to 12mL/min.

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

Optionally, the regeneration process also obtains an aqueous phase and an organic phase rich in acetic acid 2, 2-difluoroethanol, wherein the aqueous phase is recycled into the rectifying tower 2, and the organic phase rich in acetic acid 2, 2-difluoroethanol enters the rectifying tower 1 for continuous reaction.

Optionally, in step S4, the process conditions of the side mining are: and (2) carrying out top extraction at a reflux ratio of 5-30: 1, wherein the top temperature is 101-103 ℃, the side extraction temperature is 103-105 ℃, the bottom temperature is 128-132 ℃, the top extraction speed is 5-25 mL/h, and the side extraction speed is 40-60 mL/h.

Alternatively, in step S4, the side draw reflux ratio is selected from any of 5.

Optionally, in the step S4, the side mining reflux ratio is 15 to 30.

As a preferred embodiment, the following process steps are included:

s2, allowing the liquid mixture obtained in the step 1 and water to enter a rectifying tower 1 for catalytic reaction, collecting a tower top distillate, and standing to separate a water phase I and an ester phase I;

the water phase I is divided into a circulating part and a non-circulating part, and the circulating part circularly enters the rectifying tower 1 to maintain a ternary azeotropic state;

s3, enabling the non-circulating part of the water phase I in the step S2 to enter a rectifying tower 2 for further rectification, and obtaining a water phase II and an ester phase II through tower top extraction, standing and separation; the water phase II circularly enters a rectifying tower 2;

and S4, mixing the ester phase II obtained in the step S3 with the ester phase I obtained in the step S2, then carrying out alkali washing to remove acid, dehydrating, then entering a rectifying tower 4 for rectifying and purifying, and laterally collecting to obtain the electronic grade 2, 2-difluoroethyl acetate.

Optionally, in the step S2, a raw material mixture of acetic acid and 2, 2-difluoroethanol is continuously supplemented into the column bottom according to a molar ratio of 0.5-2, and the feeding speed is 40-60 mL/h.

In this application, unless otherwise indicated, the data ranges given are selected from any value within the range, and include the endpoints of the range.

In this application, normal pressure means 101.3KPa.

Alternatively, the reaction principle for preparing 2, 2-difluoroethyl acetate by catalyzing acetic acid and 2, 2-difluoroethanol in the application is as follows:

the beneficial effects that this application can produce include:

1) According to the process method for synthesizing the electronic-grade 2, 2-difluoroethyl acetate, acetic acid and 2, 2-difluoroethanol are used as raw materials, ternary azeotropic distillation of water, 2-difluoroethanol and 2, 2-difluoroethyl acetate is carried out in the synthetic rectification process, the tower top can be rapidly divided into a water layer and an ester layer, the content of the ester layer reaches 95%, and the separation cost is greatly reduced.

2) The process method comprises an alkali washing acid removal process, waste acid is not generated, the whole process is more environment-friendly, more difluoroethanol is dissolved in alkali water in the alkali washing acid removal process, and the energy consumption for separating difluoroethanol from target ester is reduced.

3) In the process method, the obtained 2, 2-difluoroethyl acetate crude product is dehydrated in the synthesis and rectification section, so that the energy consumption is greatly reduced.

4) In the process method, the operation process of repeating total reflux enrichment and then rapid extraction with a small reflux ratio is adopted for the first time in the rectification and purification working section, light components such as 2, 2-difluoroethanol and water are continuously extracted from the top of the rectification tower, and the electronic grade 2, 2-difluoroethyl acetate is obtained by adopting a middle extraction mode.

5) In the process method, the purity of the generated electronic grade 2, 2-difluoroethyl acetate product is high and can reach more than 99.99%, the moisture content is less than 20ppm, and the continuous cycle yield is as high as 98%.

6) In the process method, materials can be basically and completely recycled in the whole process, a small amount of waste water is generated, and the treatment cost is greatly reduced.

Drawings

FIG. 1 is a schematic view of an embodiment of the process of the present invention.

FIG. 2 is a schematic view of an embodiment of the process flow of the dehydration step in the process flow of the present invention.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

Unless otherwise specified, the raw materials and catalysts in the examples of the present application were all purchased commercially. The 4A molecular sieve is from a conventional commercial dehydrated molecular sieve.

The method takes acetic acid and 2, 2-difluoroethanol as raw materials, and obtains the high-purity electronic grade acetic acid 2, 2-difluoroethyl ester product through processes of synthetic rectification, ternary azeotropic product separation, by-product re-reaction circulation, alkali washing, dehydration, rectification purification and the like.

The specific process of the invention comprises the following steps:

as shown in FIG. 1, the starting materials acetic acid and 2, 2-difluoroethanol are first pre-reacted in a pre-reactor to give a liquid mixture. Continuously and stably feeding the liquid mixture after the pre-reaction into a rectifying tower 1, simultaneously supplementing water into the rectifying tower 1, continuously reacting in a normal pressure rectifying tower I filled with a homogeneous or heterogeneous catalyst, firstly fully refluxing, then extracting distillate from the tower top according to a fixed reflux ratio, and continuously supplementing raw materials into a tower kettle, after the liquid mixture is stable, the tower top temperature of the rectifying tower is 82-84 ℃, the tower kettle temperature is 108-110 ℃, extracting the distillate from the tower top, and the distillate is in a ternary azeotropic state, standing and layering the distillate from the tower top to obtain a water phase I and an ester phase I rich in 2, 2-difluoroethyl acetate, wherein one part of the water phase I circulates back to the rectifying tower 1 to maintain the ternary azeotropic state, and the other part of the water phase I enters the rectifying tower 2 to separate a water phase II and an ester phase II rich in 2, 2-difluoroethyl acetate, wherein the water phase II reflows into the rectifying tower 2 to circulate, the ester phase II rich in 2, 2-difluoroethyl acetate and the crude ester phase I rich in 2, 2-difluoroethyl acetate (2, 2-difluoroethyl acetate) are subjected to azeotropic dehydration by using a molecular sieve without using a carbonate or a molecular sieve. The ester phase mixture after acid removal and dehydration enters a rectifying tower 4 for rectification and purification, a 2, 2-difluoroethanol-rich organic phase is extracted from the top of the tower, and electronic grade 2, 2-difluoroethyl acetate is obtained by side extraction. The tower bottom liquid in the rectifying tower 2 is transferred into a rectifying tower 3 for continuous rectification to obtain an organic phase rich in 2, 2-difluoroethanol, and the organic phase rich in 2, 2-difluoroethanol collected from the top of the rectifying tower 4 are circulated together to continue the reaction in the rectifying tower 1.

As shown in fig. 2, in the process of dehydration by using anhydrous magnesium sulfate, permeable membrane or 4A molecular sieve, after the anhydrous magnesium sulfate and 4A molecular sieve after water absorption are regenerated, a water phase and an organic phase rich in 2, 2-difluoroethanol are obtained, wherein the organic phase rich in 2, 2-difluoroethanol is used as a raw material and enters a rectifying tower 1 for continuous reaction, and the water phase and a water phase II synthesized, rectified and separated by the rectifying tower 2 are combined and then enter the rectifying tower 2 for continuous rectification.

Example 1

As shown in figure 1, 768.09g of acetic acid and 1049.62g of 2, 2-difluoroethanol are added into a 2L kettle reactor, the reactor is heated to 80 ℃ after being connected with a cooling reflux device, and after the reaction is carried out for 4 hours under heat preservation, the compositions of the products obtained by sampling and detecting are 63.66wt% of 2, 2-difluoroethyl acetate, 15.65wt% of 2, 2-difluoroethanol, 11.45wt% of acetic acid and 9.24wt% of water.

Example 2

As shown in FIG. 1, starting materials acetic acid and 2, 2-difluoroethanol (acetic acid 946.61g, 2-difluoroethanol 657.73 g) were first pre-reacted in a pre-reactor to obtain a liquid mixture at a reaction temperature of 130 ℃. Continuously and stably feeding the liquid mixture after the pre-reaction into a rectifying tower 1, simultaneously adding 103g of water into the rectifying tower 1, continuously reacting in an atmospheric rectifying tower 1 filled with 19.8g of p-toluenesulfonic acid catalyst, carrying out total reflux for 1h, then stably extracting a distillate from the top of the tower according to a reflux ratio of 3. After stabilization, the tower top temperature of the rectifying tower is 82-84 ℃, the tower bottom temperature is 109 ℃, a distillate is extracted from the tower top, the extraction speed of the tower top is 50mL/h, the mass of acetic acid 2, 2-difluoroethyl ester, difluoroethanol and water in the distillate at the tower top is kept at a constant ratio of 78; wherein the composition of the water phase I is 92.38wt% of water, 2.41wt% of 2, 2-difluoroethyl acetate, 4.54wt% of 2, 2-difluoroethanol and 0.67wt% of acetic acid, and the composition of the ester phase I is 1.85wt% of water, 94.57wt% of 2, 2-difluoroethyl acetate, 3.54wt% of 2, 2-difluoroethanol and 0.01wt% of acetic acid.

1661.02g of acetic acid and 1633.87g of 2, 2-difluoroethanol are added in the whole reaction rectification process to obtain 2347.73g of 2, 2-difluoroethyl acetate.

Example 3

The raw materials and process conditions are the same as those in example 2, except that concentrated sulfuric acid is used as the catalyst, 1639.21g of acetic acid and 1580.03g of 2, 2-difluoroethanol are added in the whole reaction rectification process, and 2271.48g of acetic acid is obtained.

Example 4

Raw materials of acetic acid and 2, 2-difluoroethanol (968.21 g of acetic acid, 663.02g of 2, 2-difluoroethanol) were used, 19.9g of a strongly acidic cation exchange resin was used as a catalyst, and 1662.35g of acetic acid and 1587.18g of 2, 2-difluoroethanol were added in total to the whole reaction rectification under the same conditions as in example 2 to obtain 2277.31g of 2, 2-difluoroethyl acetate.

Example 5

The raw materials and process conditions were the same as in example 4, except that the strongly acidic cation exchange resin was mixed with the packing of the rectifying column and 1593.88g of acetic acid and 1531.51g of 2, 2-difluoroethanol were added in the whole reaction rectification to obtain 2137.20g of 2, 2-difluoroethyl acetate.

Example 6

The process conditions are the same as those of example 2, except that raw materials of acetic acid and 2, 2-difluoroethanol (937.24 g of acetic acid and 644.97g of 2, 2-difluoroethanol) are adopted, 19.7g of p-toluenesulfonic acid is adopted as the catalyst, the raw materials are continuously added into a tower kettle according to the molar ratio of the acetic acid to the 2, 2-difluoroethanol being 1. And then adding water (the water is a water phase obtained by standing and separating the overhead liquid of the rectifying tower I and circulating into the rectifying tower 1 to maintain ternary azeotropic) into the tower kettle in a molar ratio of 2, 2-difluoroethanol to water of 10, wherein the total feeding speed is 50mL/h, the overhead temperature is always maintained at 82-84 ℃, and the extraction speed is maintained at 50mL/h.

Example 7

1678.96g of a water phase I obtained by separating a distillate at the top of a rectifying tower 1 in the embodiment 6 is taken to enter a rectifying tower 2 for rectification, the mixture is heated to boil at the tower bottom under normal pressure, reflux appears at the top of the rectifying tower, a distillate is stably extracted from the top of the rectifying tower according to the reflux ratio of 3.

And (2) transferring 1602.54g of tower bottom liquid in the rectifying tower 2 into a rectifying tower 3 for continuous rectification, heating the tower bottom under normal pressure until reflux appears at the tower top, gradually raising the top temperature to 88 ℃, top-collecting an organic phase (the main component is 2, 2-difluoroethanol and water) rich in 2, 2-difluoroethanol, further raising the temperature at the tower top to 95-98 ℃, and stopping rectification when the main component at the tower top is water. 103.71g of organic phase rich in 2, 2-difluoroethanol is obtained at the top of the tower, the composition of the organic phase comprises 0.04wt% of 2, 2-difluoroethyl acetate, 68.25wt% of 2, 2-difluoroethanol, 0.00wt% of acetic acid and 31.09wt% of water, and the organic phase is circulated into the rectifying tower 1 for continuous reaction. At this time, the composition of the tower kettle is 0.00wt% of 2, 2-difluoroethyl acetate, 0.03wt% of 2, 2-difluoroethanol, 0.01wt% of acetic acid and 99.86wt% of water, and the tower kettle is subjected to sewage treatment.

Example 8

140g of saturated sodium carbonate solution and 1215.89g of crude 2, 2-difluoroethyl acetate (ester phase I, ester phase II or a mixture thereof, components before and after acid removal and ratios shown in Table 1) obtained by synthetic distillation are placed in a separating funnel, stirred and mixed uniformly for 5min at room temperature, and after standing for 5min, the mixture is separated into an ester layer and a water layer. The mass of the 2, 2-difluoroethyl acetate is basically unchanged, and the acetic acid content is remarkably reduced from 55ppm to below 1 ppm. And (5) carrying out waste alkali liquor pollution discharge treatment.

TABLE 1 comparison of components and proportions before and after deacidification of crude 2, 2-difluoroethyl acetate

Example 9

2296.07g of crude 2, 2-difluoroethyl acetate (ester phase III shown in FIG. 1) which was subjected to acid removal with alkali was taken, 300g of anhydrous magnesium sulfate was added thereto, stirred for 5min, allowed to stand for 4 hours, and then filtered with filter paper, the water content of the solution was decreased from 20400ppm to 3900ppm, and the ratio of components before and after dehydration was as shown in Table 2. The water content can be reduced to within 200ppm by multiple water removal using magnesium sulfate, but more of the organic phase is lost.

TABLE 2 comparison of components and ratios before and after dehydration with anhydrous magnesium sulfate

403.11g of anhydrous magnesium sulfate after water absorption was regenerated by a rotary evaporator at 80 ℃ under a vacuum degree of-85 kpa as shown in fig. 2, and the rotary evaporation condensate was allowed to stand for layering, wherein 366.21g of an ester layer and 34.48g of a water layer were obtained, and the components and the ratio were as shown in table 3. The water layer and the water phase I of the synthetic rectification are combined and then enter a rectifying tower 2 for continuous rectification, and the ester layer is taken as a raw material and enters the rectifying tower 1 for continuous reaction.

TABLE 3 composition and proportion of anhydrous magnesium sulfate regeneration after water absorption

Example 10

A372.21g 4A molecular sieve was packed in a 4cm diameter column of clear glass having a packing height of about 50cm, and 2603.14g of a crude 2, 2-difluoroethyl acetate product (ester phase III shown in FIG. 1) was passed through the molecular sieve from above the column using a high-pressure metering pump at a flow rate of 10mL/min. After all the crude products are dehydrated, 295g of new 4A molecular sieve is replaced, and the step is repeated. After dehydration, the water content of the crude 2, 2-difluoroethyl acetate is remarkably reduced from 18700ppm to 68ppm, and the component and proportion ratio before and after dehydration is shown in Table 4. The weight of the 4A molecular sieve was increased by 152.55g.

TABLE 4 comparison of components and ratios before and after dehydration using 4A molecular sieves

As shown in FIG. 2, the 4A molecular sieve after water absorption was regenerated using a rotary evaporator at a temperature of 80 ℃ under a vacuum of-85 kpa, and the rotary evaporation condensate was allowed to stand for stratification, wherein an ester layer was 117.3g, a water layer was 40.98g, and the components and the proportions were as shown in Table 5. The water layer and the synthetic and rectified water phase I are combined and then enter a rectifying tower 2 for continuous rectification, and the ester layer is taken as a raw material and enters the rectifying tower 1 for continuous reaction.

TABLE 5 regeneration of 4A molecular sieves after water absorption

Example 11

1875.62g of crude 2,2-difluoroethyl acetate (ester phase III, shown in FIG. 1) was dehydrated using a permeable membrane, as shown in FIG. 2, and passed through a pervaporation membrane unit, the other side of the membrane being evacuated with a vacuum pump to increase the osmotic power of the water. After 3 times of cyclic dehydration, the water content is reduced from 21500ppm to 1130ppm, and the component and proportion ratio before and after dehydration are shown in Table 6.

TABLE 6 comparison of Components and ratios before and after dehydration Using osmotic membranes

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Example 12

A2 m rectifying device (a rectifying tower 4 shown in figure 1) is set up, a side mining is added at the position of 0.5m height of a rectifying column, a continuous feeding port is added at the position of 1.5m height, and stainless steel triangular spiral ring packing is filled. 1587.43g of dehydrated crude 2, 2-difluoroethyl acetate (ester phase IV shown in FIG. 1) was added to the bottom of the rectification column, wherein 96.34wt% of 2, 2-difluoroethyl acetate, 3.05wt% of 2, 2-difluoroethanol, 0.0003wt% of acetic acid and 149ppm of water were added. Heating the tower kettle to 130 ℃ under normal pressure, setting a reflux ratio of 30, monitoring the purity of the side-extracted 2, 2-difluoroethyl acetate, and starting stable extraction when the content of the side-extracted 2, 2-difluoroethyl acetate exceeds 99.99%. At the moment, the tower top temperature is 101-103 ℃, and the side mining temperature is 103-105 ℃. The unqualified product component (organic phase rich in 2, 2-difluoroethanol) obtained by top mining is transferred into the rectifying tower 1 for continuous reaction. After the rectification, the tower kettle is light yellow and slightly viscous, the content of the acetic acid 2, 2-difluoroethyl ester is 99.98 percent, and the content of the acetic acid is 0.0135 percent. The components and the proportions continuously withdrawn from the top of the column are shown in Table 7.

TABLE 7 comparison of Components and ratios before and after dehydration Using a permeable Membrane

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

Example 13

A2 m rectifying device (a rectifying tower 4 shown in figure 1) is set up, a middle mining part is added at the position of 0.5m of the rectifying column, a continuous feeding port is added at the position of 1.5m of the rectifying column, and stainless steel triangular spiral ring packing is filled. 1611.48g of a crude dehydrated 2, 2-difluoroethyl acetate product (ester phase IV shown in FIG. 1) in which 97.14wt% of 2, 2-difluoroethyl acetate, 2.82wt% of 2, 2-difluoroethanol, 0.0002wt% of acetic acid and 152ppm of water were added to the bottom of the rectification column. Heating the tower kettle to 130 ℃ under normal pressure, and after total reflux for 1h, continuously introducing crude 2, 2-difluoroethyl acetate with the same components, and respectively setting the reflux ratio of 5; the side mining speed is 50mL/h, after the top mining and side mining organic phase compositions are stable, the compositions are analyzed, and the results are shown in tables 8 and 9, which shows that the difluoroethanol content at the tower top is increased along with the increase of the reflux ratio, and the purity of the side mining product is improved

TABLE 8 Top recovery Rate and organic phase composition vs. reflux ratio

TABLE 9 relationship of composition of side-mined organic phase and reflux ratio

Reflux ratio	Acetic acid 2, 2-Difluoroethyl ester (%)	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

Example 14

The starting materials acetic acid and 2, 2-difluoroethanol (acetic acid 946.61g, 2-2, 2-difluoroethanol 657.73 g) were first pre-reacted in a pre-reactor to give a liquid mixture at a reaction temperature of 130 ℃. Continuously and stably feeding the liquid mixture after the pre-reaction into a rectifying tower 1, simultaneously adding 103g of water into the rectifying tower 1, continuously reacting in an atmospheric rectifying tower 1 filled with 19.8g of p-toluenesulfonic acid catalyst, and performing total reflux for 1h and then performing reaction according to the weight ratio of 3:1, stably taking distillate from the top of the tower, and continuously adding raw materials into the bottom of the tower according to the molar ratio of acetic acid, 2-difluoroethanol and water of 10. The ester phase I of the tower top distillate enters a rectifying tower 4 for rectification and purification after being deacidified by anhydrous sodium carbonate and dewatered by a molecular sieve (the process conditions are the same as those in the examples 8 and 10); one part of the water phase I enters a rectifying tower 1 to maintain ternary azeotropy, the other part of the water phase I enters a rectifying tower 2 and a rectifying tower 3 to be recovered to obtain a water phase II, an ester phase II and a 2, 2-difluoroethanol-rich organic phase, the water phase II circularly enters the rectifying tower 2, the ester phase II is combined with the ester phase I, the 2, 2-difluoroethanol-rich organic phase returns to the rectifying tower 1 to be continuously rectified, and the process conditions in the rectifying towers 2 and 3 are the same as those in the embodiment 7. And (3) performing rotary evaporation on the 4A molecular sieve after water absorption, circularly feeding the obtained water phase III into a rectifying tower 2, and returning the organic phase rich in 2, 2-difluoroethanol to the rectifying tower 1 for continuous rectification. Continuously feeding for 360h, and adding 7687.16g of acetic acid, 9858.95g of 2, 2-difluoroethanol and 485.7g of residue in the bottom of a rectifying tower when all materials are basically subjected to a circulating reaction, wherein the weight percentages of the acetic acid, 2-difluoroethyl ester, 2-difluoroethanol, 1.44% of acetic acid and 6.53% of water are 89.56%; 279.64g of residue in the distillation tower 4, wherein the weight percentage of acetic acid 2, 2-difluoroethyl ester is 99.83 percent, the weight percentage of 2, 2-difluoroethanol is 0.0038 percent, the weight percentage of acetic acid is 0.0117 percent, and the weight percentage of water is 0.0004 percent; 14640.27g of electronic grade acetic acid 2, 2-difluoroethyl ester is obtained, and the total yield is 98.21%.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims

1. A process method for synthesizing electronic grade 2, 2-difluoroethyl acetate is characterized by comprising the following process steps:

s3, the water phase I obtained in the step S2 enters a rectifying tower 2 for further rectification, and a water phase II and an ester phase II are obtained through tower top extraction, standing and separation;

the water phase II circularly enters a rectifying tower 2;

2. The process according to claim 1, wherein in step S1, the feed molar ratio of acetic acid to 2, 2-difluoroethanol is 1 to 3;

preferably, in the step S1, the reaction temperature of the pre-reactor is 50-100 ℃, and the reaction time is 0.5-10 h;

preferably, the pre-reactor is a fixed bed reactor or a tank reactor.

3. The process according to claim 1, characterized in that in steps S1 and S2, the pre-reactor and the rectification column 1 contain homogeneous and/or heterogeneous catalysts;

preferably, the homogeneous catalyst is selected from the group consisting of a B acid;

preferably, the heterogeneous catalyst is selected from sulfonic acid resins.

4. The process of claim 1, wherein in the steps S2 and S3, the 2, 2-difluoroethyl acetate, the difluoroethanol and the water in the overhead distillate form a ternary azeotrope;

preferably, in the steps S2 and S3, the standing time is 1 to 10min.

5. The process according to claim 1, wherein in step S2, the molar ratio of said water to said 2, 2-difluoroethanol in step S1 is between 0.5 and 3;

preferably, the step S2 further comprises the step of continuously replenishing a raw material mixture of acetic acid, 2-difluoroethanol and water into the tower kettle according to a molar ratio of 5-10;

preferably, the water comprises the aqueous phase I separated in the rectification column 1.

6. The process method according to claim 1, wherein in the step S2, the extracted process conditions are as follows: carrying out total reflux for 0.5-3 h, then carrying out top extraction at the reflux ratio of 1-10;

preferably, in the step S2, the water phase I comprises 92-94 wt% of water, and the rest are 2, 2-difluoroethanol, 2-difluoroethyl acetate and acetic acid in sequence from high to low;

preferably, in the step S2, the ester phase I comprises 93.5 to 95.5 weight percent of 2, 2-difluoroethyl acetate, and the rest are 2, 2-difluoroethanol, water and acetic acid in sequence from high to low.

7. The process method as claimed in claim 1, wherein in the step S3, the tower bottoms of the rectifying tower 2 enter the rectifying tower 3 for further rectification, the tower top temperature is 87-89 ℃, an organic phase rich in 2, 2-difluoroethanol is obtained from the tower top, the organic phase is circulated to the rectifying tower 1 for continuous reaction, and the tower bottoms are subjected to pollution discharge treatment.

8. The process method according to claim 1, wherein in the step S4, the process conditions of the side mining are as follows: performing top extraction at a reflux ratio of 5-30: 1, wherein the temperature of the top of the tower is 101-103 ℃, the side extraction temperature is 103-105 ℃, the temperature of the bottom of the tower is 128-132 ℃, the extraction speed of the top of the tower is 5-25 mL/h, and the side extraction speed is 40-60 mL/h;

preferably, in the step S4, in the rectifying and purifying process of the rectifying tower 4, an organic phase rich in 2, 2-difluoroethanol is extracted from the top of the tower and is recycled to the rectifying tower 1.

9. The process of claim 1, wherein the alkaline scrubbing acid process comprises subjecting crude 2, 2-difluoroethyl acetate to carbonate solution to remove acid to obtain ester phase III;

the weight ratio of the carbonate to the crude 2, 2-difluoroethyl acetate product is 0.1-0.4;

preferably, the carbonate is at least one selected from sodium carbonate and potassium carbonate.

10. The process of claim 1, wherein in the step S4, the dehydrating material is at least one selected from anhydrous magnesium sulfate, molecular sieves and permeable membranes;

preferably, the weight ratio of the anhydrous magnesium sulfate to the ester phase III is 0.05-0.2;

preferably, the weight ratio of the molecular sieve to the ester phase III is from 0.18 to 0.3.