Continuous preparation method of acyl fluoride compound

Abstract

The invention discloses a continuous preparation method of an acyl fluoride compound, according to the continuous preparation method, in the presence of a catalyst, perfluoroolefin with a general formula of R1R2C = CR3R4 and carbonyl fluoride are subjected to an addition reaction to prepare the acyl fluoride compound with a general formula of CFR3R4-CR1R2-COF, R1, R2, R3 and R4 are independently selected from CnF2n + 1, and n is 0-6; the catalyst is a non-loaded body porous catalyst and consists of bicarbonate and hydrofluoride, and the bicarbonate is selected from one or more of lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, cesium bicarbonate, magnesium bicarbonate, calcium bicarbonate, strontium bicarbonate and barium bicarbonate; the hydrogen fluoride salt is selected from one or more of lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride, magnesium fluoride, calcium fluoride, strontium fluoride and barium fluoride; the mass percentage ratio of the bicarbonate to the hydrofluoride is (0-60%): (40-100%). The method is mild in continuous reaction condition, easy to operate, almost free of byproducts and suitable for continuous production.

Description

Technical Field

[0001] This invention relates to the field of fluorocarbon compounds, and more specifically to a continuous preparation method for acyl fluoride compounds. Background Technology

[0002] Perfluoroacyl fluoride compounds are an important type of fluorine-containing compound with a wide range of applications, including cleaning agents, etching agents, pesticide intermediates, and monomers for fluorine-containing materials in the electronics industry.

[0003] Existing technologies mainly employ electrochemical and chemical synthesis methods to prepare perfluoroacyl fluorides. Electrochemical fluorination suffers from numerous side reactions, low main product yields, and high energy consumption. Chemical synthesis typically utilizes a reaction vessel liquid-phase method, which offers the advantage of simple operation; however, due to the one-pot reaction, yields are often low, and it produces difficult-to-separate reaction products, such as fluorinated ketones, which affect product quality and hinder the subsequent synthesis of other compounds.

[0004] US Patent 20050080291A1 discloses a method for preparing acyl fluorides via the reaction of carbonyl fluorides (COF). This reaction uses a catalyst supported on a porous compound, specifically a fluoride salt such as LiF and NaF, CaF2, BaF2, MgF2, or SrF2 (10-30%) supported on the porous compound. This method suffers from problems such as high reaction temperature, easy catalyst deactivation, short catalyst lifetime, and low catalytic efficiency.

[0005] Chinese patent CN107935884A discloses a method for preparing acyl fluorides. In an organic solvent, in the presence of an alkali metal fluoride and a co-solvent, a perfluoroolefin with the general formula R1R2C=CR3R4 undergoes an addition reaction with a carbonyl fluoride to obtain an acyl fluoride with the general formula R1R2(COF)C-CFR3R4. This method requires the use of a co-solvent, and after the reaction is complete, the alkali metal fluoride and the co-solvent are difficult to recover and separate.

[0006] Chinese patent CN108424375A discloses a method for preparing acyl fluoride. The catalyst is an active component, an alkali metal fluoride, supported on a carrier. The alkali metal fluoride is at least one selected from lithium fluoride, potassium fluoride, sodium fluoride, rubidium fluoride, or cesium fluoride. The carrier is activated carbon or other metal fluorides, and the other metal fluorides are at least one selected from aluminum fluoride, magnesium fluoride, iron fluoride, chromium fluoride, or zinc fluoride. The mass percentage of the active component to the carrier is 0-20%:80%-100%. This method uses a carrier and requires a certain reaction pressure, resulting in reduced catalytic efficiency and increased difficulty in continuous operation.

[0007] Chinese patent CN106946669A discloses a method for preparing heptafluoroisobutyryl fluoride, using activated carbon-supported NaF, KF, CsF, or SbF5 as the catalyst, with a catalyst loading of 5-25%. This method exhibits low conversion and selectivity.

[0008] Therefore, it is necessary to provide a continuous method for preparing perfluoroacyl fluoride compounds that is fast in reaction, highly selective, operates under mild conditions, has a simple process, high conversion and yield of products, is environmentally friendly, produces few byproducts such as fluorinated ketones, and is suitable for industrial production, in order to solve the above-mentioned technical problems. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention proposes a continuous preparation method for acyl fluoride compounds that features fast reaction rate, high selectivity, mild operating conditions, simple process, high conversion and yield of products, is environmentally friendly, produces few by-products, and is suitable for industrial production.

[0010] This invention provides a continuous preparation method for acyl fluoride compounds. In the presence of a catalyst, a perfluoroolefin with the general formula R1R2C=CR3R4 undergoes an addition reaction with a carbonyl fluoride to prepare an acyl fluoride compound with the general formula CFR3R4-CR1R2-COF. R1, R2, R3, and R4 are independently selected from CnF2n+1, where n = 0 to 6.

[0011] The catalyst is an unsupported bulk porous catalyst composed of bicarbonate and bifluoride. The bicarbonate is selected from one or more of lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, cesium bicarbonate, magnesium bicarbonate, calcium bicarbonate, strontium bicarbonate, and barium bicarbonate. The bifluoride is selected from one or more of lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride, magnesium fluoride, calcium fluoride, strontium fluoride, and barium fluoride.

[0012] The mass percentage of the bicarbonate to the hydrogen fluoride is 0-60%:40-100%.

[0013] Furthermore, the perfluoroolefin is selected from one or more of hexafluoropropylene, tetrafluoroethylene, octafluoro-1-butene, and octafluoro-2-butene.

[0014] Furthermore, when the perfluoroolefin is selected from hexafluoropropylene, tetrafluoroethylene, octafluoro-1-butene, or octafluoro-2-butene, the bicarbonate is selected from potassium bicarbonate, and the hydrogen fluoride is selected from potassium fluoride.

[0015] Furthermore, the molar ratio of the perfluoroolefin to the carbonyl fluoride is 1:0.9 to 1.5; even further, the molar ratio of the perfluoroolefin to the carbonyl fluoride is 1:1 to 1.4. Within this molar ratio range, the selectivity is high, the conversion and yield of the product are high, and the by-products are few.

[0016] The addition reaction described in this invention can be carried out in a reactor used in the art, and preferably, the reactor for the addition reaction is a tubular reactor.

[0017] The addition reaction described in this invention is a gas-phase addition reaction, with a reaction pressure of 0 MPa, a reaction temperature of 100–350°C, and a contact time of 5–100 s. Preferably, the reaction temperature is 150–310°C, and the contact time is 20–80 s. This results in a fast reaction rate, high selectivity, high product conversion and yield, and low byproduct production.

[0018] The method for preparing the catalyst according to the present invention includes the following steps:

[0019] S1: Dissolve a metal hydroxide salt in water to form a solution, and simultaneously introduce carbon dioxide and hydrogen fluoride into the solution. The molar ratio of carbon dioxide to hydrogen fluoride is 1:1 to 3. Adjust the pH value to be less than 7. After the reaction, let it stand to produce a partial precipitate. Filter the precipitate to obtain a filter cake and filtrate.

[0020] S2: The filtrate is evaporated to dryness to obtain a solid salt, and the solid salt and the filter cake are mixed to obtain a catalyst precursor.

[0021] Furthermore, the evaporation conditions in S2 are 0.1 MPa vacuum and 100°C.

[0022] The activation method of the catalyst described in this invention is as follows: the catalyst precursor is pulverized, pressed into tablets, and then placed in a reactor for calcination at 300°C for 1–3 hours, 400°C for 1–3 hours, and 500°C for 1–6 hours; then, N2 containing 5% F2 is introduced and fluorinated at 500°C for 10–20 hours, with a gas space velocity of 100 h⁻¹. The purpose of high-temperature calcination during catalyst activation is to induce the regular release of small molecule gases such as water, carbon dioxide, and hydrogen fluoride, generating micropores of 1–50 nanometers. These smaller pores restrict molecular diffusion and improve reaction selectivity. The purpose of fluorination is to fluorinate the surface hydroxyl groups to improve the reaction conversion rate.

[0023] The catalyst of the present invention has micropores of 1 to 50 nm, further having micropores of 5 to 45 nm; even further having micropores of 5 to 35 nm; and even further having micropores of 5 to 10 nm.

[0024] The bicarbonate and hydrogen fluoride salts of the catalyst described in this invention are mixed during the preparation process.

[0025] The technical solution of the present invention has the following technical advantages compared with the prior art:

[0026] (1) The catalyst used in this invention is simple and readily available, and has high catalytic efficiency.

[0027] (2) The continuous reaction conditions of this invention are mild, easy to operate, and produce almost no by-products, making it suitable for continuous production. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternatives, improvements, and equivalents that may be included within the scope of the claims.

[0029] Preparation of catalyst A

[0030] Potassium hydroxide was dissolved in water, and carbon dioxide and hydrogen fluoride were introduced for neutralization, maintaining a carbon dioxide to hydrogen fluoride molar ratio of 1:2. The pH was adjusted to less than 7, and after thorough stirring, the mixture was allowed to stand for 24 hours, resulting in partial precipitate formation. The precipitate was filtered and separated, and the filter cake was reserved. The filtrate was evaporated to dryness under a vacuum of 0.1 MPa and at 100°C to obtain a solid salt. The solid salt and filter cake were mixed to prepare preliminary catalysts: bicarbonate and hydrogen fluoride salts.

[0031] The obtained preliminary catalyst was pulverized and pressed into tablets. The catalyst was then loaded into a tubular reactor and calcined at high temperature: 300℃ for 2 hours, 400℃ for 2 hours, and 500℃ for 4 hours. Finally, a 5% F2 / N2 mixture was introduced and fluorinated at 500℃ for 6 hours with a gas space velocity of 100 h⁻¹. The catalyst pore size was measured to be 5–10 nanometers, thus obtaining the activated catalyst.

[0032] Example 1: Continuous Synthesis of Perfluoroisobutyryl Fluoride (CF3)2CFCOF

[0033] Catalyst A was introduced into a 200 cm³ tubular reactor with a diameter of 2 cm. Hexafluoropropylene and carbonyl fluoride were introduced at a reaction temperature of 270 °C, with a molar ratio of hexafluoropropylene to carbonyl fluoride of 1:1.1, a contact time of 60 s, and a reaction pressure of 0 MPa. The conversion rate of hexafluoropropylene was 100%, and the selectivity for heptafluoroisobutyryl fluoride was 99.2%.

[0034] Example 2: Continuous Synthesis of Pentafluoropropionyl Fluoride CF3CF2COF

[0035] Catalyst A was introduced into a 200 cm³ tubular reactor with a diameter of 2 cm. Tetrafluoropropylene and carbonyl fluoride were introduced at a reaction temperature of 230 °C, with a molar ratio of tetrafluoropropylene to carbonyl fluoride of 1:1.1, a contact time of 40 s, and a reaction pressure of 0 MPa. The conversion rate of tetrafluoropropylene was 100%, and the selectivity for pentafluoropropionyl fluoride was 99.4%.

[0036] Example 3: Continuous Synthesis of 2,3,3,4,4,4-Hexafluoro-2-(trifluoromethyl)butyryl fluoride CF3CF2CF(CF3)COF

[0037] Catalyst A was introduced into a 200 cm³ tubular reactor with a diameter of 2 cm. Octafluoro-1-butene and carbonyl fluoride were introduced at a reaction temperature of 310 °C, with a molar ratio of 1:1.2 for octafluoro-1-butene to carbonyl fluoride, a contact time of 70 s, and a reaction pressure of 0 MPa. The conversion rate of octafluoro-1-butene was 100%, and the selectivity for 2,3,3,4,4,4-hexafluoro-2-(trifluoromethyl)butyryl fluoride was 99.6%.

[0038] Preparation of catalyst B

[0039] Cesium hydroxide was dissolved in water, and neutralized by introducing carbon dioxide and hydrogen fluoride, maintaining a carbon dioxide to hydrogen fluoride molar ratio of 1:2. The pH was adjusted to less than 7, and after thorough stirring, the mixture was allowed to stand for 24 hours, resulting in partial precipitate formation. The precipitate was filtered off, and the filter cake was reserved. The filtrate was evaporated to dryness under a vacuum of 0.1 MPa and at 100°C to obtain a solid salt. The solid salt and filter cake were mixed to prepare preliminary catalysts: bicarbonate and hydrogen fluoride salts.

[0040] The obtained preliminary catalyst was pulverized and pressed into tablets. The catalyst was then loaded into a tubular reactor and calcined at high temperature: 300℃ for 2 hours, 400℃ for 2 hours, and 500℃ for 4 hours. Finally, a 5% F2 / N2 mixture was introduced and fluorinated at 500℃ for 6 hours with a gas space velocity of 100 h⁻¹. The catalyst pore size was measured to be 10–20 nanometers, thus obtaining the activated catalyst.

[0041] Example 4: Continuous Synthesis of Perfluoroisobutyryl Fluoride (CF3)2CFCOF

[0042] Catalyst B was introduced into a 200 cm³ tubular reactor with a diameter of 2 cm. Hexafluoropropylene and carbonyl fluoride were introduced at a reaction temperature of 270 °C, with a molar ratio of hexafluoropropylene to carbonyl fluoride of 1:1.1, a contact time of 50 s, and a reaction pressure of 0 MPa. The conversion rate of hexafluoropropylene was 100%, and the selectivity for heptafluoroisobutyryl fluoride was 99.3%.

[0043] Comparative Example 1: Continuous synthesis of perfluoroisobutyryl fluoride (CF3)2CFCOF using an unactivated catalyst

[0044] The precursors of catalyst A, bicarbonate and hydrogen fluoride (unactivated), were introduced into a 200 cm³ tubular reactor with a diameter of 2 cm. Hexafluoropropylene and carbonyl fluoride were introduced at a reaction temperature of 270 °C, with a molar ratio of hexafluoropropylene to carbonyl fluoride of 1:1.1, a contact time of 60 s, and a reaction pressure of 0 MPa. The conversion rate of hexafluoropropylene was 23%, and the selectivity for heptafluoroisobutyryl fluoride was 25.9%.

[0045] Comparative Example 2: Continuous Synthesis of Perfluoroisobutyryl Fluoride (CF3)2CFCOF Catalyzed by Commercially Available Bicarbonate and Bifluoride Salts

[0046] Commercially available potassium bicarbonate and potassium bifluoride were pulverized and compressed into tablets. The catalyst was then loaded into a tubular reactor and subjected to high-temperature calcination: 300℃ for 2 hours, 400℃ for 2 hours, and 500℃ for 4 hours. Finally, a 5% F2 / N2 mixture was introduced and fluorinated at 500℃ for 6 hours with a gas space velocity of 100 h⁻¹. The catalyst pore size was determined to be 5–10 nanometers, thus obtaining the activated catalyst.

[0047] The catalyst was introduced into a 200 cm³ tubular reactor with a diameter of 2 cm. Hexafluoropropylene and carbonyl fluoride were introduced at a reaction temperature of 270 °C, with a molar ratio of hexafluoropropylene to carbonyl fluoride of 1:1.1, a contact time of 60 s, and a reaction pressure of 0 MPa. The conversion rate of hexafluoropropylene was 31.2%, and the selectivity for heptafluoroisobutyryl fluoride was 57.3%.

Claims

1. A method for continuous preparation of an acyl fluoride compound, characterized by: In the presence of a catalyst, perfluoroolefins of the general formula R1R2C=CR3R4 undergo an addition reaction with carbonyl fluoride to prepare acyl fluoride compounds of the general formula CFR3R4-CR1R2-COF, where R1, R2, R3, and R4 are independently selected from CnF2n+1, where n = 0 to 6; The catalyst is an unsupported bulk porous catalyst composed of bicarbonate and bifluoride. The bicarbonate is selected from one or more of lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, cesium bicarbonate, magnesium bicarbonate, calcium bicarbonate, strontium bicarbonate, and barium bicarbonate. The bifluoride is selected from one or more of lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride, magnesium fluoride, calcium fluoride, strontium fluoride, and barium fluoride. The mass percentage of the bicarbonate to the hydrogen fluoride is 0-60%:40-100%.

2. The method for continuous preparation of acyl fluoride compounds according to claim 1, characterized by: The perfluoroolefin is selected from one or more of hexafluoropropylene, tetrafluoroethylene, octafluoro-1-butene, and octafluoro-2-butene.

3. The method of claim 1, wherein the method is continuous. The molar ratio of the perfluoroolefin to the carbonyl fluoride is 1:0.9 to 1.

5.

4. The method of claim 3, wherein the method comprises: The molar ratio of the perfluoroolefin to the carbonyl fluoride is 1:1 to 1.

4.

5. The method of claim 1, wherein the acyl fluoride compound is continuously prepared by the method. The addition reaction is carried out in a tubular reactor with a reaction pressure of 0 MPa, a reaction temperature of 100–350 °C, and a contact time of 5–100 s.

6. The method of claim 1, wherein the acyl fluoride compound is continuously prepared by the method. The preparation method of the catalyst includes the following steps: S1: Dissolve a metal hydroxide salt in water to form a solution, and simultaneously introduce carbon dioxide and hydrogen fluoride into the solution. The molar ratio of carbon dioxide to hydrogen fluoride is 1:1 to 3. Adjust the pH value to be less than 7. After the reaction, let it stand to produce a partial precipitate. Filter the precipitate to obtain a filter cake and filtrate. S2: The filtrate is evaporated to dryness to obtain a solid salt, and the solid salt and the filter cake are mixed to obtain a catalyst precursor.

7. The process for the continuous preparation of acyl fluoride compounds according to claim 6, characterized in that: The evaporation conditions in S2 are 0.1 MPa vacuum and 100°C.

8. The method of claim 6, wherein the acyl fluoride compound is continuously prepared by the method. The activation method of the catalyst is: crushing the catalyst precursor, tabletting and shaping, then loading into a reactor for calcination, calcination at 300°C for 1-3h, calcination at 400°C for 1-3h, calcination at 500°C for 1-6h; then passing 5% F2-containing N2 at 500°C for fluorination for 10-20h, gas space velocity is 100h -1 .

9. The method of claim 1, wherein the method is continuous. The catalyst has micropores of 1–50 nm.