Preparation method of fluorine-containing alkyne

Abstract

The invention discloses a preparation method of fluorine-containing alkyne, which comprises the following steps: under the action of a catalyst, Rf-CX1 = CHX2 and hydrogen are subjected to hydrodehalogenation reaction to obtain fluorine-containing alkyne Rf-C = CH, in the formula, X1 and X2 are independently selected from Cl, Br or I; rf is CnF2n + 1, and n is a natural number from 1 to 6; the catalyst comprises a carbon carrier and active components which are loaded on the carbon carrier and are of a hollow structure, and the active components comprise at least one first metal selected from silver, copper, nickel and cobalt and at least one second metal selected from palladium, platinum and rhodium. The preparation process has the advantages of high catalytic activity, high product selectivity, easiness in industrial application and the like.

Description

Technical Field

[0001] This invention relates to the field of fluorochemicals, and more specifically to a method for preparing fluorinated alkynes. Background Technology

[0002] The value of fluorinated compounds in medicine, pesticides, medical imaging, and materials science is undeniable. At least 20% of pharmaceuticals and 30% of pesticides contain at least one fluorine atom, making fluorine chemistry an important component of organic chemistry. Introducing fluorine-containing groups into molecules often alters their structure, electronic properties, polarity, and metabolic activity, thus affecting their physicochemical properties and biological activity. In 1970, only 2% of drugs contained fluorine atoms; currently, the number of fluorinated drug molecules has risen to 25%.

[0003] Fluoroalkynes are important synthons for introducing fluorine-containing segments into organic molecules, and they can also be used as monomers to prepare fluorinated polymers, making them very important industrial products. Currently, publicly reported processes for preparing fluoroalkynes mainly fall into two categories:

[0004] (I) Liquid-phase preparation process

[0005] There are two types of liquid-phase preparation processes:

[0006] 1) Adopt Rf-C≡CH is prepared by elimination reaction using (X = F, Cl, Br and I) as raw materials under the action of alkali.

[0007] Patent CN101675017A discloses a method for preparing 3,3,3-trifluoro-1-propyne (TFPY) from cis-1-chloro-3,3,3-trifluoropropane (Z-1233zd). The method uses potassium hydroxide as a base and water and methanol as solvents, reacting at 38°C. The conversion rate of the raw material Z-1233zd is 98.6%, the selectivity of the product TFPY is 98.3%, and the yield is 96.9%. However, when the raw material is E-1233zd, no product is formed under the same conditions. This reaction is a trans-elimination reaction; when the leaving group is in the trans position, elimination can occur smoothly. Therefore, Z-1233zd can successfully eliminate one molecule of HCl to obtain TFPY. However, the raw material Z-1233zd is difficult to obtain and prepare, making it difficult to meet the needs of industrial production. Although E-1233zd is an inexpensive industrial product, the reaction conditions for direct elimination reaction are very harsh and the yield is low, making it unsuitable for industrial production.

[0008] 2) with Using raw materials (X = Cl and Br), under the action of active metals, such as zinc powder and magnesium shavings, the reaction yields Rf-C≡CH.

[0009] Patent CN 117342922 A discloses a method for preparing TFPY using 3,3,3-trifluoro-1,2-dichloropropene as a raw material. This process uses zinc powder (300 mesh) as a reducing agent and ethanol as a solvent, at a temperature of 100... ℃ After 12 hours of reaction, the conversion rate of the raw materials was 81.7%, and the selectivity of TFPY was 99.5%. This method has a long reaction time, generates a large amount of waste, has high production costs, and is difficult to apply industrially.

[0010] (II) Gas-solid phase catalytic dehydrogenation process for preparing HX

[0011] Patent CN113004117A discloses a gas-phase catalytic dehydrogenation process for the preparation of TFPY. This method uses barium fluoride as a support and an alkali metal fluoride as a catalyst. Z-1233zd is introduced at 400°C for 100 seconds at atmospheric pressure. After 20 hours of reaction, the product is washed with water and then with alkali to obtain the organic compound. GC analysis shows that the conversion rate of Z-1233zd is 23.1%, and the selectivity for TFPY is 95.6%. When the feedstock is E-1233zd, the conversion rate is 22.3%, and the selectivity for TFPY is 96.1%. When the feedstock is E-1,3,3,3-tetrafluoropropylene, the conversion rate is 46.8%, and the selectivity for TFPY is 30.1%.

[0012] US9353030A discloses a method for preparing TFPY from 2-chloro-3,3,3-trifluoropropene (R1233xf) via catalytic deHCl removal. The method uses activated carbon as a catalyst, the reaction temperature is 650°C, the residence time of R1233xf is 30 s, the conversion rate of the raw material is 44%, the selectivity of TFPY is 25%, and the yield is 57%.

[0013] Patent WO2010 / 95764 discloses a preparation process using E-1233zd as raw material and KF / C as catalyst, with a reaction temperature of 400℃, a contact time of 60s, a pressure of 0.1MPa, a raw material conversion rate of 16.7%, and a TFPY selectivity of 83.2%.

[0014] In summary, gas-solid phase catalytic HX removal processes generally suffer from low catalyst activity, low feed conversion rate, and low yield, making them unsuitable for industrial production. Therefore, it is necessary to develop a fluorinated alkyne synthesis process that boasts high reaction yield, low production cost, safety, environmental friendliness, and suitability for industrial application. Summary of the Invention

[0015] To address the aforementioned technical problems, this invention proposes a gas-phase preparation process for fluorinated alkynes that features readily available raw materials, high reaction yield, simple operation, safety, environmental friendliness, and suitability for industrial application.

[0016] The objective of this invention is achieved through the following technical solution:

[0017] A method for preparing a fluorinated alkyne, the method comprising:

[0018] Rf-CX under the action of a catalyst 1 =CHX 2 The fluorinated alkyne is obtained by hydrodehalogenation reaction with hydrogen; the catalyst comprises a carbon support and an active component supported on the carbon support in a hollow spherical structure, the active component comprising:

[0019] The first metal is selected from at least one of silver, copper, nickel, and cobalt;

[0020] The second metal is selected from at least one of palladium, platinum, and rhodium;

[0021] The reaction equation is as follows:

[0022]

[0023] In the formula, X 1 X 2 Independently selected from Cl, Br, or I; preferably, X 1 X 2 Independently selected from Cl or Br; more preferably, X 1 X 2 Both are Cl. Rf is C. n F 2n+1 n is a natural number from 1 to 6; preferably, n is 1, 2 or 3.

[0024] Regarding the active component of the present invention, preferably, the first metal is selected from copper, silver or nickel, and the second metal is selected from palladium or platinum; more preferably, the active component is a combination of copper or silver, palladium or platinum.

[0025] Further, the catalyst contains 0.1-10% by mass of the first metal and 0.1-10% by mass of the second metal, with the remainder being a carbon support. Preferably, the first metal contains 1-5% by mass of mass and the second metal contains 1-5% by mass of mass.

[0026] This invention employs a bimetallic catalyst, with a potential difference between the first and second metals. Therefore, the catalyst prepared via a redox method allows the active component to form a highly efficient hollow structure (e.g., hollow spheres) on a carbon support. This structure accelerates the adsorption of reactants and the desorption of products, shortening residence time and avoiding the formation of over-hydrogenated byproducts, thus improving product selectivity and yield. The hollow structure of the active component also allows for rapid transfer of reaction heat, preventing high-temperature sintering of the catalyst and improving its stability and lifespan. Specifically, the second metal can be deposited on the surface of the catalyst cluster, while the first metal dissolves inside the cluster. The difference in their reduction potentials forms the hollow structure, as detailed below. Figure 1 As shown: (a) the first metal atom tends to oxidize at the crystal plane with the highest surface free energy and enter the solution; (b) when the first metal is oxidized, the second metal ion is reduced on the surface of the first metal ion and deposited on the crystal plane with a lower surface free energy; (c) as the first metal atom is continuously oxidized and removed, the second metal ion is continuously reduced and deposited, and voids are formed due to their positional differences; (d) the second metal ion deposited on the outer layer can effectively protect the first metal ion below it from oxidation, and the voids formed are the main sites for redox reactions. With the continuous deposition and mass transport of the second metal on the surface, the voids gradually disappear and close when the reaction ends, thus forming a hollow structure.

[0027] Specifically, the catalyst is prepared by the following steps:

[0028] A1. Carbon carrier treatment: Activated carbon is stirred in a 20-70 wt% nitric acid solution for 6-12 h, then rinsed with deionized water until neutral, washed with anhydrous ethanol, and finally dried at 80-120℃ for more than 8 h to obtain the carbon carrier.

[0029] A2. First metal loading: The first metal salt is dissolved in deionized water and fully dissolved. Then, the treated carbon support is added and impregnated for 4 to 10 hours and dried. Then, the carbon support loaded with the first metal is obtained by reduction treatment in a mixed gas of hydrogen and nitrogen. The reduction treatment temperature is 280 to 350℃, the treatment time is 2 to 8 hours, and the ratio of nitrogen to hydrogen is (1 to 5): 1.

[0030] A3. Second Metal Support: A carbon support loaded with the first metal is dispersed in deionized water or alcohol. A solution of the second metal salt is added dropwise while stirring. After the addition is complete, stirring continues for 6–18 hours. The catalyst is then washed with deionized water or alcohol until neutral and dried to obtain the catalyst. The alcohol is selected from at least one of methanol, ethanol, n-propanol, or isopropanol.

[0031] Furthermore, in step A1, the stirring temperature of the activated carbon in the nitric acid solution is 30–80°C.

[0032] In step A2, the first metal salt is selected from the chloride, nitrate, sulfate, or acetate salts of the first metal. In a specific embodiment, the first metal salt may be copper chloride, copper nitrate, nickel chloride, nickel nitrate, silver nitrate, or silver acetate.

[0033] In step A3, the second metal salt is selected from the chloride or nitrate salt of a second metal. In a specific embodiment, the second metal salt may be palladium chloride, palladium nitrate, platinum chloride, platinum nitrate, rhodium chloride, or rhodium nitrate.

[0034] In the preparation process of fluorinated alkynes, the raw material Rf-CX 1 =CHX 2 The molar ratio of hydrogen to hydrogen is 1:(1.2-5), preferably 1:(2-3).

[0035] The reaction temperature is 250–450℃, the reaction pressure is atmospheric pressure to 1.0 MPa, and the feed space velocity is 20–1500 h⁻¹. -1 Preferably, the reaction temperature is 250–350°C, the reaction pressure is atmospheric pressure to 0.5 MPa, and the feed space velocity is 200–800 h⁻¹. -1 .

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This invention uses gas-phase hydrogenation dehalogenation to prepare fluorinated alkynes, overcoming the shortcomings of existing gas-phase preparation processes such as low catalytic activity and low product yield. The raw material conversion rate reaches over 95%, the product selectivity reaches over 90%, the amount of waste is small, continuous production is possible, and the production cost is low, making it highly feasible for industrial application. Attached Figure Description

[0038] Appendix Figure 1 This is a schematic diagram of the formation of the hollow structure of the catalyst, where: small spheres represent the first metal, large spheres represent the second metal, and gray represents the first or second metal in its oxidized state. Detailed Implementation

[0039] 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.

[0040] Preparation Example 1: Pd-Ag / AC Catalyst

[0041] The catalyst preparation steps in this example are as follows:

[0042] S1. Place activated carbon in a beaker containing 20% ​​nitric acid solution and stir for 6 hours. Then rinse with deionized water until neutral, wash with anhydrous ethanol, and finally dry at 105°C for 8 hours to obtain carbon support.

[0043] S2. Dissolve 1.1g AgNO3 in 60mL of deionized water, stir until fully dissolved, add 20g of acid-treated carbon support, impregnate for 4h, and then dry at 105℃ for 8h; then reduce at 320℃ with a mixed gas of nitrogen and hydrogen (N2:H2=3:1) for 4h to obtain Ag-loaded carbon support.

[0044] S3. Disperse the Ag-loaded carbon support prepared above in deionized water, and add 5 mL of PdCl2 hydrochloric acid solution (PdCl2). 2 + The concentration of 0.04 g / mL was diluted with 60 mL of deionized water and then added dropwise to the Ag-loaded carbon support solution. After the addition was complete, the mixture was stirred for 12 h. The reaction solution was filtered, and the filter cake was washed with deionized water until neutral. Then it was transferred to a vacuum drying oven and dried at 80 °C for 12 h to obtain the Pd-Ag / AC catalyst, denoted as cat.1.

[0045] Preparation Example 2: Pd-Ni / AC Catalyst

[0046] The operation of this preparation example is the same as that of Preparation Example 1, except that 1.8g Ni(NO3)2·6H2O is used instead of AgNO3 for the first metal salt. All other operations remain unchanged, and a Pd-Ni / AC catalyst is prepared, denoted as cat.2.

[0047] Preparation Example 3: Pd-Cu / AC Catalyst

[0048] The operation of this preparation example is the same as that of Preparation Example 1, except that: 1.40 g of CuCl2·2H2O is used instead of AgNO3 for the first metal salt, and all other operations remain unchanged. The Pd-Cu / AC catalyst is prepared and is denoted as cat.3.

[0049] Preparation Example 4: Pt-Cu / AC Catalyst

[0050] The procedure in this preparation example is the same as in Preparation Example 3, except that the second metal salt is prepared using a hydrochloric acid solution of PtCl2 (PtCl2). 2+ A hydrochloric acid solution with a concentration of 0.08 g / mL was used to replace PdCl2. 2+ With the concentration of 0.04 g / mL unchanged, and all other operations remaining the same, a Pt-Cu / AC catalyst was prepared, denoted as cat.4.

[0051] Preparation Example 5: Pt-Ag / AC Catalyst

[0052] The procedure in this preparation example is the same as in Preparation Example 1, except that the second metal salt is prepared using a hydrochloric acid solution of PtCl2 (PtCl2). 2+ A hydrochloric acid solution with a concentration of 0.08 g / mL was used to replace PdCl2. 2+ The concentration of the catalyst was reduced to 0.04 g / mL, and the volume was reduced to 4 mL, while all other operations remained unchanged. This yielded a Pt-Ag / AC catalyst, denoted as cat.5. Example 6: Preparation of Ru-Cu / AC catalyst

[0053] The procedure in this preparation example is the same as in Preparation Example 3, except that the second metal salt is prepared using RuCl3·3H2O solution (Ru 3+ A hydrochloric acid solution with a concentration of 0.007 g / mL was used to replace PdCl2. 2+ The concentration of the catalyst was increased to 0.04 g / mL, and the volume was increased to 30 mL, while all other operations remained unchanged. This yielded a Ru-Cu / AC catalyst, denoted as cat. 6. Comparative preparation example 1 - commercially available Pd / C catalyst.

[0054] The catalyst used was a commercially available Pd / C catalyst with coconut shell activated carbon as the support. The Pd loading was 2.5%, denoted as cat.D1.

[0055] Comparative Preparation Example 2: Pd-Cu / AC Catalyst (Non-Hollow Structure)

[0056] The catalyst preparation steps in this comparative preparation example are as follows:

[0057] S1. The carbon support treatment method is the same as in Preparation Example 1;

[0058] S2. Add 1.40g CuCl2·2H2O to 5mL of PdCl2 hydrochloric acid solution (Pd 2+ The concentration of the catalyst was 0.1 g / mL. Then, 60 mL of deionized water was added and stirred evenly. 20 g of the carbon support treated in step S1 was added and impregnated for 6 h. Then, it was dried at 105 °C for 8 h. After that, it was reduced at 320 °C with a mixture of nitrogen and hydrogen (N2:H2=3:1) for 4 h to obtain the Pd-Cu / AC catalyst, denoted as cat.D2.

[0059] Example 1

[0060] This embodiment provides a method for preparing 3,3,3-trifluoro-1,2-dichloro-1-propene by hydrogenation and dechlorination, as detailed below:

[0061] The catalysts from Preparation Examples 1-6 and Comparative Preparation Examples 1-2 were loaded into a reaction tube (made of Inconel 600, 10 mm inner diameter, 500 mm long) at a volume of 10 mL. After the catalyst was loaded, N2 was introduced (flow rate 30 mL / min), and the temperature was slowly raised to 300 °C. Then the nitrogen gas was turned off, and a mixture of the raw material 3,3,3-trifluoro-1,2-dichloro-1-propene and hydrogen (V) was introduced. 原料 V H2 =1:3), reaction pressure is atmospheric pressure, and feed space velocity is 600 h⁻¹. -1 The reaction products were analyzed by gas chromatography, and the results are shown in Table 1 below:

[0062] Table 1 Evaluation results of different catalysts

[0063]

[0064]

[0065] As can be seen from Table 1 above, the hollow bimetallic catalyst prepared by the present invention exhibits excellent catalytic performance in the preparation of fluorinated alkynes, and can simultaneously possess high feed conversion rate and product selectivity, thus having very good advantages for industrial application.

Claims

1. A method for preparing fluorinated alkynes, characterized in that: The preparation method includes: Rf-CX under the action of a catalyst. 1 =CHX 2 The fluorinated alkyne is obtained by hydrodehalogenation reaction with hydrogen; the catalyst comprises a carbon support and an active component supported on the carbon support in a hollow structure, the active component comprising: The first metal is selected from at least one of silver, copper, nickel, and cobalt; The second metal is selected from at least one of palladium, platinum, and rhodium; The reaction equation is as follows: In the formula, X 1 X 2 Independently selected from Cl, Br, or I; Rf is C n F 2n+1 n is a natural number from 1 to 6.

2. The method for preparing fluorinated alkynes according to claim 1, characterized in that: In the catalyst, the mass content of the first metal is 0.1-10%, the mass content of the second metal is 0.1-10%, and the remainder is a carbon support.

3. The method for preparing fluorinated alkynes according to claim 1, characterized in that: Raw material Rf-CX 1 =CHX 2 The molar ratio of hydrogen to nitrogen is 1:(1.2-5).

4. The method for preparing fluorinated alkynes according to claim 1, characterized in that: The reaction temperature is 250–450℃, the reaction pressure is atmospheric pressure to 1.0 MPa, and the feed space velocity is 20–1500 h⁻¹. -1 .

5. The method for preparing fluorinated alkynes according to claim 1 or 2, characterized in that: The catalyst is prepared by the following steps: A1. Carbon carrier treatment: Activated carbon is stirred in a 20-70 wt% nitric acid solution for 6-12 h, then rinsed with deionized water until neutral, washed with anhydrous ethanol, and finally dried at 80-120℃ for more than 8 h to obtain the carbon carrier. A2. First metal loading: The first metal salt is dissolved in deionized water until fully dissolved, then the treated carbon support is added and impregnated for 4-10 hours, and then dried; then it is reduced in a mixture of hydrogen and nitrogen gas to obtain the carbon support loaded with the first metal. A3. Second metal support: The carbon support loaded with the first metal is dispersed in deionized water or alcohol, and the second metal salt solution is added while stirring. After the addition is completed, stirring is continued for 6 to 18 hours. Then, it is washed with deionized water or alcohol until neutral, and the catalyst is obtained after drying.

6. The method for preparing fluorinated alkynes according to claim 5, characterized in that: In step A1, the stirring temperature of activated carbon in nitric acid solution is 30–80°C.

7. The method for preparing fluorinated alkynes according to claim 5, characterized in that: The first metal salt is selected from the chloride, nitrate, sulfate, or acetate salts of the first metal; The second metal salt is selected from the chloride or nitrate salt of the second metal.

8. The method for preparing fluorinated alkynes according to claim 1, characterized in that: The first metal of the active component is selected from copper, silver or nickel, and the second metal is selected from palladium or platinum.

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