阅读说明：本技术 一种复合固体酸、其制备方法及应用 (Composite solid acid, preparation method and application thereof ) 是由 赵刚 孙磊杰 孙家乐 陈君 花文杰 陆颖鹏 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种复合固体酸、其制备方法及应用。本申请中公开的复合固体酸的制备方法如下所示：将氧化物和氟化物加入水中,过滤得固体,将所得固体在150～350℃下加热12～100小时,得复合固体酸即可；所述的氧化物为氧化镁、氧化铝、氧化锌、氧化铁、氧化铜、二氧化钛、二氧化锆、二氧化硅、硅藻土和蒙脱土中的一种或多种；所述的氟化物为氟化镁、氟化钙、氟化锌、氟化铜和氟化铝中的一种或多种。本发明中的复合固体酸能应用于制备二氟乙酸酯类化合物,该制备方法具有较高的原子经济性、制备步骤简洁、制备过程适用于连续管道化反应,工艺过程安全、反应时间短、产率高、三废很少、是一种环境友好的制备方法。(The invention discloses a composite solid acid, a preparation method and application thereof. The preparation method of the complex solid acid disclosed in the present application is as follows: adding an oxide and a fluoride into water, filtering to obtain a solid, and heating the obtained solid at 150-350 ℃ for 12-100 hours to obtain a composite solid acid; the oxide is one or more of magnesium oxide, aluminum oxide, zinc oxide, ferric oxide, copper oxide, titanium dioxide, zirconium dioxide, silicon dioxide, diatomite and montmorillonite; the fluoride is one or more of magnesium fluoride, calcium fluoride, zinc fluoride, copper fluoride and aluminum fluoride. The composite solid acid can be applied to the preparation of difluoroacetate compounds, and the preparation method has the advantages of high atom economy, simple preparation steps, suitability for continuous pipeline reaction in the preparation process, safe technical process, short reaction time, high yield, few three wastes and environmental friendliness.)

1. A method for preparing a complex solid acid, comprising the steps of:

adding an oxide and a fluoride into water, filtering to obtain a solid, and heating the obtained solid at 150-350 ℃ for 12-100 hours to obtain a composite solid acid;

the oxide is one or more of magnesium oxide, aluminum oxide, zinc oxide, ferric oxide, copper oxide, titanium dioxide, zirconium dioxide, silicon dioxide, diatomite and montmorillonite;

the fluoride is one or more of magnesium fluoride, calcium fluoride, zinc fluoride, copper fluoride and aluminum fluoride.

2. The method of producing a complex solid acid according to claim 1, wherein the method of producing a complex solid acid satisfies one or more of the following conditions:

in the preparation method of the composite solid acid, the oxide is one or more of magnesium oxide, aluminum oxide, titanium dioxide, silicon dioxide, kieselguhr and montmorillonite, and preferably one or two of the oxides;

in the preparation method of the composite solid acid, the fluorinating agent is aluminum fluoride or magnesium fluoride;

in the preparation method of the composite solid acid, the molar ratio of the oxidant to the fluorinating agent is 0.1: 1-10: 1;

in the preparation method of the composite solid acid, the concentration of the fluoride in water is 1-20 mol/L;

in the preparation method of the composite solid acid, the heating temperature is 250-320 ℃;

in the preparation method of the composite solid acid, the heating time is 20-60 hours.

3. The method of producing a complex solid acid according to claim 2, wherein the method of producing a complex solid acid satisfies one or more of the following conditions:

in the preparation method of the composite solid acid, when the oxide is one, the oxidant is magnesium oxide, titanium dioxide, alumina, diatomite or montmorillonite;

in the preparation method of the composite solid acid, when the oxides are two, the oxides are two of kieselguhr, alumina and titanium dioxide, preferably kieselguhr and alumina and kieselguhr and titanium dioxide;

in the preparation method of the composite solid acid, when the two oxides are used, the molar ratio of the two oxidants is 0.1: 1-10: 1, preferably 1: 1;

in the preparation method of the composite solid acid, the molar ratio of the oxidant to the fluorinating agent is 0.5: 1-2: 1, such as 0.5:1, 1:1 or 2: 1;

in the preparation method of the composite solid acid, the concentration of the fluoride in water is 2-10 mol/L, preferably 2-3.3 mol/L;

in the preparation method of the composite solid acid, the heating temperature is 250 ℃, 280 ℃, 300 ℃ or 320 ℃;

in the preparation method of the composite solid acid, the heating time is 24-36 hours.

4. The method of claim 2, wherein the oxidizing agent and the fluorinating agent are either:

scheme A:

the oxide is magnesium oxide, and the fluoride is aluminum fluoride;

scheme B:

the oxide is titanium dioxide, and the fluoride is magnesium fluoride;

scheme C:

the oxide is aluminum oxide, and the fluoride is magnesium fluoride;

scheme D:

the oxide is titanium dioxide, and the fluoride is aluminum fluoride;

scheme E:

the oxide is aluminum oxide, and the fluoride is aluminum fluoride;

scheme F:

the oxide is diatomite and the fluoride is aluminum fluoride;

scheme G:

the oxide is montmorillonite, and the fluoride is magnesium fluoride;

scheme H:

the oxide is diatomite and alumina, and the fluoride is magnesium fluoride;

scheme I:

the oxide is diatomite and titanium dioxide, and the fluoride is magnesium fluoride.

5. A composite solid acid prepared by the method for preparing a composite solid acid according to any one of claims 1 to 4, wherein the particle size of the composite solid acid is preferably 100 to 200 meshes, 200 to 300 meshes or 300 to 400 meshes.

6. A method for preparing difluoroacetate, which comprises the following steps:

carrying out a rearrangement reaction of 1,1,2, 2-tetrafluoroethyl alkyl ether and the composite solid acid as described in claim 5at a temperature of 80-200 ℃ to obtain difluoroacetic acid ester as described below;

r is C₁-C₆An alkyl group.

7. The method of claim 6, wherein the method of making difluoroacetate satisfies one or more of the following conditions:

in the preparation method of difluoroacetic acid ester, the C₁-C₆Alkyl is C₁-C₄Alkyl, preferably C₁-C₃An alkyl group;

in the preparation method of the difluoroacetic acid ester, the rearrangement reaction is carried out in a kettle type reactor or a tubular type reactor, and the kettle type reactor is preferably an autoclave;

in the preparation method of difluoroacetic acid ester, if the reaction is carried out in a closed system, the pressure is 5-20 atm when the rearrangement reaction temperature is 80-200 ℃, for example, the pressure is 10-16 atm when the rearrangement reaction temperature is 120-200 ℃;

in the preparation method of the difluoroacetic acid ester, if the reaction is carried out in an open system, the pressure of the rearrangement reaction is normal pressure;

in the method for preparing difluoroacetic acid ester, the mass ratio of the 1,1,2, 2-tetrafluoroethyl alkyl ether to the composite solid acid is 1:0.3 to 1:3, preferably 1:0.7 to 1:1.5, such as 1:0.7, 1:0.8, 1:0.9, 1:0.95, 1:1, 1:1.2 or 1: 1.4;

in the preparation method of difluoroacetate, the temperature of the rearrangement reaction is 120-200 ℃, such as 120 ℃, 130 ℃, 140 ℃, 150 ℃, 155 ℃, 160 ℃, 165 ℃, 170 ℃, 180 ℃ or 200 ℃;

in the preparation method of the difluoroacetic acid ester, the reaction time is 2-10 hours, preferably 2.5-6 hours, such as 2.5 hours, 3 hours, 3.5 hours, 3.6 hours, 4 hours, 5.5 hours or 6 hours;

in the rearrangement reaction, the rearrangement reaction is carried out in the presence of a protective gas, preferably nitrogen.

8. The method of claim 7, wherein the method of making difluoroacetate satisfies one or more of the following conditions:

when the rearrangement reaction is carried out in a tank reactor, the rearrangement reaction is followed by a post-treatment, which preferably comprises the following steps: washing with water, layering to obtain organic phase, drying the organic phase, distilling, and collecting product according to boiling point of the product;

when the rearrangement reaction is carried out in the tubular reactor, the inner diameter of the tubular reactor is 3-5 mm, preferably 4 mm;

when the rearrangement reaction is carried out in the tubular reactor, the length of the tubular reactor is 50-70 cm, preferably 50-60 cm;

when the rearrangement reaction is carried out in a tubular reactor, the 1,1,2, 2-tetrafluoroethyl alkyl ether is introduced into the reaction tube in a gas form;

when the rearrangement reaction is carried out in a tubular reactor, the residence time of the 1,1,2, 2-tetrafluoroethyl alkyl ether in the reaction tube is 2 to 120 seconds, preferably 40 to 100 seconds, for example 30 to 60 seconds;

when the rearrangement reaction is carried out in a tubular reactor, the rearrangement reaction is followed by a post-treatment, which preferably comprises the following steps: cooling to obtain an initial product, distilling and collecting the product according to the boiling point of the product.

9. The complex solid acid promoted-CF of claim 5₂Use of the conversion of an O-structure into a-COO-structure.

10. Use according to claim 9, in a rearrangement reaction according to any one of claims 6 to 8.

Technical Field

The invention belongs to the technical field of chemical synthesis, and relates to a composite solid acid, and a preparation method and application thereof. In particular to a synthesis method for preparing difluoroacetic ester by promoting defluorination rearrangement reaction of 1,1,2, 2-tetrafluoroethyl alkyl ether by a composite solid acid 'one-pot' method.

Background

Difluoroacetate is widely used as an important fluorine-containing fine chemical in agricultural chemicals, medicines, organic synthesis, and the like (j. jaunzems and m. braun, org. process res.dev.2014,18,1055). Wherein the ethyl difluoroacetate is also called ethyl difluoroacetate and has a molecular formula C₄H₆F₂O₂Colorless transparent liquid with boiling point of 99 ℃, and important reagents containing difluoromethylene and synthetic building blocks are commonly used; the ethyl difluoroacetate can be subjected to reduction, condensation, amidation and other reactions, and important intermediates containing difluoro groups can be synthesized through the reactions, so that the fluorine-containing pesticide and medicine can be further prepared. The method for preparing ethyl difluoroacetate reported in the literature at present comprises the following steps: 1) preparing difluoroacetic acid from explosive and difficult-to-transport tetrafluoroethylene as a raw material, and carrying out ammoniation, acid catalytic hydrolysis and esterification to generate a large amount of solid ammonium salt, wastewater and the like; 2) dichloroacetyl chloride reacts with HF through liquid phase or gas phase, and the process equipment is easy to corrode, needs high temperature and has low yield; 3) use of 1,1,2, 2-tetrafluoroethylether in the presence of a corrosive Lewis acid SbF₅,TiF₄(D.C. England, J.org.chem.1984,49,4007), protonic acid concentrated sulfuric acid (J.A. Young; P.Tarrant, J.Am.chem.Soc.1979,71,2432.) or single solid lineLewis acid Al₂O₃(CN 105461560 A)，Al₃PO₄(EP 2522652A 1) Lewis acids at elevated temperatures (A)>After difluoroacetyl fluoride is generated at 200 ℃, an ethanol solvent is used for absorption to generate esterification reaction, and corrosive hydrofluoric acid is generated in the same way, as shown in the specification.

Disclosure of Invention

The invention aims to solve the technical problems of complex synthesis method and production process, equipment corrosion, low yield, three wastes (waste solid, gas and water) and the like of the existing difluoroacetic acid ester. Therefore, the invention provides a composite solid acid, a preparation method and application thereof, the composite solid acid can promote 1,1,2, 2-tetrafluoroethyl alkyl ether to carry out defluorination rearrangement reaction to prepare difluoroacetic ester, the rearrangement reaction has higher atom economy, simple preparation steps, the preparation process is suitable for continuous pipeline reaction, the process is safe, the reaction time is short, the yield is high, three wastes are few, and the method is an environment-friendly new method.

The invention provides a preparation method of a composite solid acid, which comprises the following steps:

adding an oxide and a fluoride into water, filtering to obtain a solid, and heating the obtained solid at 150-350 ℃ for 12-100 hours to obtain a composite solid acid;

the oxide is one or more of magnesium oxide, aluminum oxide, zinc oxide, ferric oxide, copper oxide, titanium dioxide, zirconium dioxide, silicon dioxide, diatomite and montmorillonite;

the fluoride is one or more of magnesium fluoride, calcium fluoride, zinc fluoride, copper fluoride and aluminum fluoride.

In the preparation method of the composite solid acid, the oxide can be one or more of magnesium oxide, aluminum oxide, titanium dioxide, silicon dioxide, diatomite and montmorillonite, and preferably one or two oxides.

In the preparation method of the composite solid acid, when the oxide is one, the oxidant is preferably magnesium oxide, titanium dioxide, alumina, diatomite or montmorillonite.

In the preparation method of the composite solid acid, when the oxides are two, the oxides are two of kieselguhr, alumina and titanium dioxide, preferably kieselguhr and alumina and kieselguhr and titanium dioxide; the molar ratio between the two oxidants is preferably 0.1:1 to 10:1, more preferably 1:1.

In the preparation method of the composite solid acid, the fluorinating agent is preferably aluminum fluoride or magnesium fluoride.

In the preparation method of the composite solid acid, the molar ratio of the oxidant to the fluorinating agent can be 0.1: 1-10: 1, preferably 0.5: 1-2: 1, such as 0.5:1, 1:1 or 2: 1.

In the preparation method of the composite solid acid, the concentration of the fluoride in water can be 1-20 mol/L, preferably 2-10 mol/L, and more preferably 2-3.3 mol/L.

In one embodiment, the oxide is magnesium oxide and the fluoride is aluminum fluoride.

In one embodiment, the oxide is titanium dioxide and the fluoride is magnesium fluoride.

In one embodiment, the oxide is alumina and the fluoride is magnesium fluoride.

In one embodiment, the oxide is titanium dioxide and the fluoride is aluminum fluoride.

In one embodiment, the oxide is alumina and the fluoride is aluminum fluoride.

In one embodiment, the oxide is diatomaceous earth and the fluoride is aluminum fluoride.

In one embodiment, the oxide is montmorillonite and the fluoride is magnesium fluoride.

In one embodiment, the oxide is diatomaceous earth and alumina and the fluoride is magnesium fluoride.

In one embodiment, the oxides are diatomaceous earth and titanium dioxide and the fluoride is magnesium fluoride.

In the preparation method of the composite solid acid, the heating temperature is preferably 250-320 ℃, such as 250 ℃, 280 ℃, 300 ℃ or 320 ℃.

In the preparation method of the composite solid acid, the heating time is preferably 20-60 hours, and more preferably 24-36 hours.

The invention also provides a composite solid acid prepared by the preparation method of the composite solid acid.

In one embodiment, the particle size of the complex solid acid is preferably 100 to 200 mesh, 200 to 300 mesh, or 300 to 400 mesh.

The invention also provides the composite solid acid promoted-CF₂Use of the conversion of an O-structure into a-COO-structure.

The invention also provides a preparation method of difluoroacetate, which comprises the following steps:

carrying out rearrangement reaction on 1,1,2, 2-tetrafluoroethyl alkyl ether and the composite solid acid at the temperature of 80-200 ℃ to obtain difluoroacetic acid ester shown in the specification;

r is C₁-C₆An alkyl group.

In the preparation method of difluoroacetic acid ester, the C₁-C₆Alkyl (e.g., methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-methyl-1-butyl, 2-methyl-2-propyl, 1-pentyl, 2-pentyl, 3-pentyl, 2-methyl-2-butyl, 3-methyl-1-butyl, 2-methyl-1-butyl, 1-hexyl, 2-hexyl, 3-hexyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 3-methyl-3-pentyl, 2-methyl-3-pentyl, etc.), 2, 3-dimethyl-2-butyl or 3, 3-dimethyl-2-butyl, preferably methyl, ethyl or butyl), preferably C₁-C₄Alkyl, more preferably C₁-C₃An alkyl group.

In the process for the preparation of difluoroacetic acid esters, the rearrangement reaction may be carried out in a tank reactor, preferably an autoclave, or in a tubular reactor.

In the method for preparing difluoroacetic acid ester, it is known to those skilled in the art that if the reaction is carried out in a closed system (for example, a tank reactor), the pressure in the system may also vary with the increase of the temperature of the reaction system, for example, the pressure may be 5 to 20atm when the rearrangement reaction is heated to a temperature of 80 to 200 ℃ or 10 to 16atm when the rearrangement reaction is heated to a temperature of 120 to 200 ℃. (more specifically, for example, the rearrangement reaction temperature is 120 ℃ under a pressure of 15atm, the rearrangement reaction temperature is 130 ℃ under a pressure of 12atm, the rearrangement reaction temperature is 160 ℃ under a pressure of 14atm, the rearrangement reaction temperature is 200 ℃ under a pressure of 10atm, the rearrangement reaction temperature is 170 ℃ under a pressure of 16atm, the rearrangement reaction temperature is 160 ℃ under a pressure of 14atm, the rearrangement reaction temperature is 140 ℃ under a pressure of 14atm, the rearrangement reaction temperature is 180 ℃ under a pressure of 10atm, the rearrangement reaction temperature is 120 ℃ under a pressure of 13atm, the rearrangement reaction temperature is 140 ℃ under a pressure of 15atm)

In the preparation method of difluoroacetic acid ester, as is known to those skilled in the art, when the reaction is carried out in an open system (such as a tubular reactor), the pressure of the reaction is kept constant with the increase of the reaction temperature, and the pressure is normal pressure (i.e. 1 atm).

In the method for producing difluoroacetic acid ester, the mass ratio of the 1,1,2, 2-tetrafluoroethyl alkyl ether to the composite solid acid may be 1:0.3 to 1:3, preferably 1:0.7 to 1:1.5, for example, 1:0.7, 1:0.8, 1:0.9, 1:0.95, 1:1, 1:1.2 or 1: 1.4.

In the method for preparing difluoroacetate, the temperature of the rearrangement reaction is preferably 120 to 200 ℃, for example, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 155 ℃, 160 ℃, 165 ℃, 170 ℃, 180 ℃ or 200 ℃.

When the rearrangement reaction is carried out in a tank reactor, the rearrangement reaction preferably comprises a post-treatment, and the post-treatment preferably comprises the following steps: washing with water, separating the layers to obtain an organic phase, drying the organic phase, distilling and collecting the product according to the boiling point of the product, for example, collecting 84-86 ℃ fractions if the product is methyl difluoroacetate; for example, if the product is ethyl difluoroacetate, collecting the fraction at 98-100 ℃; for example, if the product is butyl difluoroacetate, the fraction at 136-137 ℃ is collected.

In the preparation method of difluoroacetate, the rearrangement reaction can be carried out in a tubular reactor, and the inner diameter of the tubular reactor is preferably 3-5 mm, and more preferably 4 mm; the length of the tubular reactor is preferably 50-70 cm, and more preferably 50-60 cm.

When the rearrangement reaction is carried out in a tubular reactor, the 1,1,2, 2-tetrafluoroethyl alkyl ether is preferably introduced into the reaction tube in the form of a gas.

When the rearrangement reaction is carried out in a tubular reactor, the reaction temperature is preferably 30 to 150 ℃ higher than the boiling point temperature of the raw material 1,1,2, 2-tetrafluoroethyl alkyl ether, preferably 60 to 120 ℃ higher, for example 93 ℃ higher, 98 ℃ higher, 103 ℃ higher or 108 ℃ higher.

When the rearrangement reaction is carried out in a tubular reactor, the residence time of the 1,1,2, 2-tetrafluoroethyl alkyl ether in the reaction tube is preferably 2 to 120 seconds, more preferably 40 to 100 seconds, for example 30 to 60 seconds.

When the rearrangement reaction is carried out in a tubular reactor, the rearrangement reaction preferably comprises a post-treatment, which preferably comprises the following steps: cooling to obtain a primary product, distilling and collecting the product according to the boiling point of the product, for example, collecting 84-86 ℃ fractions if the product is methyl difluoroacetate; for example, if the product is ethyl difluoroacetate, collecting the fraction at 98-100 ℃; for example, if the product is butyl difluoroacetate, the fraction at 136-137 ℃ is collected.

The rearrangement reaction takes 1,1,2, 2-tetrafluoroethyl alkyl ether as a reaction end point, and the reaction time can be 2 to 10 hours, preferably 2.5 to 6 hours, such as 2.5 hours, 3 hours, 3.5 hours, 3.6 hours, 4 hours, 5.5 hours or 6 hours.

In the rearrangement reaction, the rearrangement reaction is preferably carried out in the presence of a protective gas, preferably nitrogen.

The invention also provides the application of the composite solid acid in the rearrangement reaction.

The above preferred conditions can be arbitrarily combined to obtain preferred embodiments of the present invention without departing from the common general knowledge in the art.

The reagents and starting materials used in the present invention are commercially available.

The positive progress effects of the invention are as follows: the invention provides a novel composite solid acid and a method for preparing difluoroacetic ester by using the composite solid acid, wherein the method has the advantages of high atom economy, simple preparation steps, suitability for continuous pipeline reaction in the preparation process, safe technical process, short reaction time, high yield and few three wastes, and is an environment-friendly novel method.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.

Preparation of the composite solid acid:

example 1:

preparation of I type composite solid acid I-A: adding 40.3g (1.0mol) of magnesium oxide and 84.0g (1.0mol) of aluminum fluoride into 500mL of deionized water, stirring for half an hour, standing, filtering to obtain a powder blocky solid, heating to 300 ℃ under the condition of nitrogen, keeping the temperature for 24 hours, cooling to room temperature, grinding into powder of 100 meshes and 200 meshes to prepare the composite solid acid I-A.

Example 2:

preparation of I type composite solid acid I-B: adding 79.9g (1.0mol) of titanium dioxide and 62.3g (1.0mol) of magnesium fluoride into 500mL of deionized water, stirring for half an hour, standing, filtering to obtain powder block solid, heating to 250 ℃ under the condition of argon, keeping the temperature for 36 hours, cooling to room temperature, grinding into 400-mesh powder of 300 meshes, and preparing the composite solid acid I-B.

Example 3:

preparation of type I composite solid acid I-C: adding 101.9g (1.0mol) of alumina and 62.3g (1.0mol) of magnesium fluoride into 500mL of deionized water, stirring for half an hour, standing, filtering to obtain powder block solid, heating to 300 ℃ under the condition of argon, keeping the temperature for 24 hours, cooling to room temperature, grinding into powder of 100 meshes and 200 meshes to prepare the composite solid acid I-C.

Example 4:

preparation of type I composite solid acid I-D: adding 40g (0.5mol) of titanium dioxide and 84.0g (1.0mol) of aluminum fluoride into 500mL of deionized water, stirring for half an hour, standing, filtering to obtain powder block solid, heating to 280 ℃ under the condition of nitrogen, keeping the temperature for 36 hours, cooling to room temperature, grinding into powder of 100 meshes and 200 meshes to prepare the composite solid acid I-D.

Example 5:

preparation of type I composite solid acid I-E: adding 101.9g (1.0mol) of alumina and 84.0g (1.0mol) of aluminum fluoride into 500mL of deionized water, stirring for half an hour, standing, filtering to obtain a powder block solid, heating to 300 ℃ under the condition of nitrogen, keeping the temperature for 24 hours, cooling to room temperature, grinding into powder of 100 meshes and 200 meshes to prepare the composite solid acid I-E.

Example 6:

preparation of type II composite solid acid II-A: adding 60g (1.0mol) of diatomite and 84.0g (1.0mol) of aluminum fluoride into 500mL of deionized water, stirring for half an hour, standing, filtering to obtain powder block-shaped solid, heating to 300 ℃ under the condition of nitrogen, keeping the temperature for 36 hours, cooling to room temperature, grinding into powder of 100 meshes and 200 meshes to prepare the composite solid acid II-A.

Example 7:

preparation of type II composite solid acid II-B: adding 30g (0.5mol) of kieselguhr and 62.3g (1.0mol) of magnesium fluoride into 300mL of deionized water, stirring for half an hour, standing, filtering to obtain powder blocky solid, heating to 300 ℃ under the condition of nitrogen, keeping the temperature for 24 hours, cooling to room temperature, grinding into 300-mesh powder of 200 meshes, and preparing the composite solid acid II-B.

Example 8:

preparation of type II composite solid acid II-C: adding 60g of montmorillonite and 62.3g (1.0mol) of magnesium fluoride into 300mL of deionized water, stirring for half an hour, standing, filtering to obtain powder block solid, heating to 300 ℃ under the condition of nitrogen, keeping the temperature for 24 hours, cooling to room temperature, grinding into 300-mesh powder of 200 meshes, and preparing the composite solid acid II-C.

Example 9:

preparation of type III composite solid acid III-A: adding 30.0g (0.5mol) of diatomite, 51.0g (0.5mol) of alumina and 62.3g (1.0mol) of magnesium fluoride into 500mL of deionized water, stirring for half an hour, standing, filtering to obtain a powdery blocky solid, heating to 320 ℃ under the condition of nitrogen, keeping the temperature for 24 hours, cooling to room temperature, grinding to 200-mesh powder with 300 meshes to prepare the composite solid acid III-A.

Example 10:

preparation of type III composite solid acid III-B: adding 60.0g (1.0mol) of diatomite, 79.9g (1.0mol) of titanium dioxide and 62.3g (1.0mol) of magnesium fluoride into 500mL of deionized water, stirring for half an hour, standing, filtering to obtain powder block-shaped solid, heating to 320 ℃ under the condition of nitrogen, keeping the temperature for 24 hours, cooling to room temperature, grinding to 200-mesh 300-mesh powder to prepare the composite solid acid III-B.

Preparation of difluoroacetate:

example 11:

in a 500mL reaction kettle, 116g (MW 146,0.8mol) of the substrate 1,1,2, 2-tetrafluoroethylethyl ether and 120g of the complex solid acid I-a were added. The temperature is gradually increased to 120 ℃, the reaction pressure reaches 15atm at most, and the reaction time is 3 hours. After cooling to room temperature, the reaction mixture was taken out, washed with ice water (2X 100mL), and the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to obtain 88.7g (yield 90%) of ethyl difluoroacetate as a colorless liquid having a boiling point of 98-100 ℃.¹H NMR(CDCl₃,400MHz)δ(ppm):1.35(t,³J＝7,2Hz,3H),4.34(q,³J＝7.2Hz,2H),5.89(t,²J_HF＝54Hz,1H)；¹⁹F NMR(CDCl₃,376MHz)δ(ppm):126.8(d,²J_HF＝54Hz,2F)。

Example 12:

in a 500mL reaction kettle, 116g (MW 146,0.8mol) of the substrate 1,1,2, 2-tetrafluoroethylethyl ether and 120g of the complex solid acid I-B were added. The temperature is gradually increased to 130 ℃, the reaction pressure reaches 12atm at most, and the reaction time is 3.5 hours. After cooling to room temperature, the reaction mixture was taken out, washed with ice water (2X 100mL), and the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to obtain 80.7g (yield: 82%) of ethyl difluoroacetate as a colorless liquid having a boiling point of 98-100 ℃.

Example 13:

in a 500mL reaction kettle, 132g (MW 132.0,1.0mol) of substrate 1,1,2, 2-tetrafluoroethylmethyl ether, and 160g of complex solid acid I-C were added. The temperature is gradually increased to 160 ℃, the reaction pressure reaches 14atm at most, and the reaction time is 2.5 hours. After cooling to room temperature, the reaction mixture was taken out, washed with ice water (2X 100mL), and the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to collect 100g (yield 90%) of methyl difluoroacetate as a colorless liquid having a boiling point of 84-86 ℃.¹H NMR(CDCl₃,400MHz)δ(ppm):3.91(q,³J＝7.2Hz,3H),5.92(t,²J_HF＝53.2Hz,1H)；¹⁹F NMR(CDCl₃,376MHz)δ(ppm):127.8(d,²J_HF＝53.2Hz,2F)。

Example 14:

in a 500mL reaction kettle, 174g (MW 174.0,1.0mol) of substrate 1,1,2, 2-tetrafluoroethylbutyl ether and 160g of complex solid acid I-C were added. The temperature is gradually increased to 200 ℃, the reaction pressure reaches 10atm at most, and the reaction time is 3.6 hours. After cooling to room temperature, the reaction mixture was taken out, washed with ice water (2X 100mL), the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to obtain 115.6g (yield: 76%) of n-butyl difluoroacetate as a colorless liquid, boiling point: 136-.¹H NMR(CDCl₃,400MHz)δ(ppm):0.96(t,³J＝7.2Hz,3H),1.38-1.60(m,4H),4.07(q,³J＝7.2Hz,2H),5.86(t,²J_HF＝54Hz,1H)；¹⁹F NMR(CDCl₃,376MHz)δ(ppm):124.6(d,²J_HF＝53.2Hz,2F)。

Example 15:

in a 500mL reaction kettle, 116g (MW 146,0.8mol) of the substrate 1,1,2, 2-tetrafluoroethyl ethyl ether and 80g of the complex solid acid I-D were gradually heated to 170 ℃ and the reaction pressure reached up to 16atm, and the reaction time was 4.0 hours. After cooling to room temperature, the reaction mixture was taken out, washed with ice water (2X 100mL), and the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to obtain 78.7g (yield 80%) of ethyl difluoroacetate as a colorless liquid having a boiling point of 98-100 ℃.

Example 16:

in a 500mL reaction kettle, 132g (MW 132.0,1.0mol) of substrate 1,1,2, 2-tetrafluoroethylmethyl ether, and 160g of complex solid acid I-E were charged. The temperature is gradually increased to 160 ℃, the reaction pressure reaches 14atm at most, and the reaction time is 2.5 hours. After cooling to room temperature, the reaction mixture was taken out, washed with ice water (2X 100mL), and the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to collect 100g (yield 90%) of methyl difluoroacetate as a colorless liquid having a boiling point of 84-86 ℃.

Example 17:

in a 500mL reaction kettle, 116g (MW 146,0.8mol) of the substrate 1,1,2, 2-tetrafluoroethylethyl ether and 140g of the complex solid acid II-a were added. The temperature is gradually increased to 140 ℃, the reaction pressure reaches 14atm at most, and the reaction time is 4.0 hours. After cooling to room temperature, the reaction mixture was taken out, washed with ice water (2X 100mL), and the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to obtain 79.7g (yield 80%) of ethyl difluoroacetate as a colorless liquid having a boiling point of 98-100 ℃.

Example 18:

in a 500mL reaction kettle, 116g (MW 146,0.8mol) of the substrate 1,1,2, 2-tetrafluoroethylethyl ether and 90g of the complex solid acid II-B were added. The temperature is gradually increased to 180 ℃, the reaction pressure reaches 10atm at most, and the reaction time is 4.0 hours. After cooling to room temperature, the reaction mixture was taken out, washed with ice water (2X 100mL), and the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to obtain 79.7g (yield 80%) of ethyl difluoroacetate as a colorless liquid having a boiling point of 98-100 ℃.

Example 19:

in a 500mL reaction kettle, 116g (MW 146,0.8mol) of the substrate 1,1,2, 2-tetrafluoroethylethyl ether and 110g of the complex solid acid II to C were added. The temperature is gradually increased to 180 ℃, the reaction pressure reaches 10atm at most, and the reaction time is 4.0 hours. The reaction mixture was cooled to room temperature, taken out, washed with ice water (2X 100mL), and the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to obtain 74.5g (yield: 75%) of ethyl difluoroacetate as a colorless liquid having a boiling point of 98-100 ℃.

Example 20:

in a 500mL reaction kettle, 116g (MW 146,0.8mol) of the substrate 1,1,2, 2-tetrafluoroethylethyl ether and 140g of the complex solid acid III-a were added. The temperature is gradually increased to 120 ℃, the reaction pressure reaches 13atm at most, and the reaction time is 4.0 hours. After cooling to room temperature, the reaction mixture was taken out, washed with ice water (2X 100mL), and the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to obtain 86.5g (yield: 87%) of ethyl difluoroacetate as a colorless liquid having a boiling point of 98-100 ℃.

Example 21:

in a 500mL reaction kettle, 116g (MW 146,0.8mol) of the substrate 1,1,2, 2-tetrafluoroethylethyl ether, and 160g of the complex solid acid III-B were added. The temperature is gradually increased to 140 ℃, the reaction pressure reaches 15atm at most, and the reaction time is 4.0 hours. After cooling to room temperature, the reaction mixture was taken out, washed with ice water (2X 100mL), and the lower organic phase was collected, dried with anhydrous calcium chloride, and distilled under normal pressure to obtain 88.6g (yield 90%) of ethyl difluoroacetate as a colorless liquid having a boiling point of 98-100 ℃.

Example 22:

a316 stainless steel tube reactor (the inner diameter is 4mm, the length is 50cm) is filled with 2.5Kg of powder of 100 meshes of the composite solid acid I-A, the raw material 1,1,2, 2-tetrafluoroethyl ethyl ether 2920g (MW 146,20mol) is continuously introduced into a reaction tube in a gaseous state under the protection of nitrogen and normal pressure, the reaction temperature is controlled between 150 ℃ and 155 ℃, the reactant stays in the tube for 30-60s, the reaction time is 6 hours, the gaseous product is cooled to obtain 2281.6g of an initial product (yield is 92%), the atmospheric distillation is carried out, the boiling point is collected, and 2132.8g of colorless liquid ethyl difluoroacetate (yield is 86%) is obtained.

Example 23:

a316 stainless steel tube reactor (the inner diameter is 4mm, the length is 60cm) is filled with 4.0Kg of powder of a 200-mesh composite solid acid I-E, 2920g (MW is 146,20mol) of 1,1,2, 2-tetrafluoroethyl ethyl ether serving as a raw material is continuously introduced into a reaction tube in a gaseous state under the protection of nitrogen and normal pressure, the reaction temperature is controlled to be between 160 and 165 ℃, reactants stay in the tube for 30 to 60s, the reaction time is 5.5 hours, the gaseous product is cooled to obtain 2356.0g of an initial product (the yield is 95 percent), the initial product is distilled under normal pressure, the boiling point is collected to be 98 to 100 ℃, and 2232.0g of colorless liquid ethyl difluoroacetate (the yield is 90 percent) is obtained.

Finally, simultaneous experimental screening has shown that the yield of the reaction using only metal oxides or fluorides alone under optimal reaction conditions is below 10%, the main product being acyl fluoride (HCF)₂COF)。