A method for preparing fluorine-containing sulfur point monomer

Abstract

The present invention discloses a method for preparing a fluorine-containing sulfide monomer, which is prepared by the following reaction route: #imgabs0# wherein n≥1; when n=2: #imgabs1#

Description

Technical Field

[0001] The present invention relates to the technical field of fluorine materials, and in particular to a method for preparing a fluorine-containing sulfur point monomer. Background Art

[0002] Fluoroelastomers are a class of high-performance elastomers that exhibit excellent heat, oxidation, and solvent resistance, as well as excellent tensile strength and compression set properties. Many fluoroelastomers require the presence of curing site monomers, which carry cross-linking functional groups that can be induced to form an inert network structure that is heat-resistant, oxidation-resistant, and fluid-resistant. Among these, fluoroelastomers containing cyano groups can form a triazine cross-linked network structure under the action of a catalyst. This aromatic heterocyclic structure exhibits very stable heat resistance and exhibits excellent performance even under continuous high-temperature use. It also exhibits excellent chemical resistance, maintaining excellent heat resistance even when exposed to harsh chemicals. It can be applied to harsher chemical environments and extreme temperature applications where other elastomers are not suitable. However, curing site monomers containing cyano groups are key special functional monomers for the synthesis of high-performance fluoroelastomers and are banned from sale in my country. Currently, the synthesis methods disclosed in foreign patents are complex and inefficient. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a method for preparing a fluorine-containing sulfide monomer to solve the problem that the prior art method for preparing a cyanide-containing sulfide monomer is complex and inefficient.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for preparing a fluorine-containing sulfide monomer is prepared using the following reaction route:

[0006]

[0007] Where n≥1;

[0008] When n=2:

[0009]

[0010] Preferably, the specific steps are as follows:

[0011] Step 1: 2-cyano-2,2-difluoroacetyl fluoride is reacted with hexafluoropropylene oxide in the presence of a catalyst, and the reaction product is purified to obtain a 2-substituted tetrafluoropropionyl fluoride compound;

[0012] Step 2: Select the product 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride prepared in step 1 as a raw material. Under the action of an inorganic base, 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride is subjected to a cleavage reaction to obtain a fluorine-containing sulfide point monomer perfluoro(8-cyano-5-methyl-3,6-dioxo-1-ene).

[0013] Preferably, in step 1, the reaction temperature is -20°C to 20°C; the absorption amount of hexafluoropropylene oxide is 1 to 3 equivalents of 2-cyano-2,2-difluoroacetyl fluoride; the catalyst is one of CsF, RbF, KF, KF-SiO2, and KF / 18-Crown-6, and the amount of the catalyst used is 5 mol% to 20 mol% of the amount of 2-cyano-2,2-difluoroacetyl fluoride calculated by molar percentage.

[0014] Preferably, in step 1, the reaction solvent is one of acetonitrile, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether.

[0015] Preferably, in step 2, the inorganic base is potassium carbonate or sodium carbonate; the molar ratio of 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride to the inorganic base is 1:(1-3); and the reaction temperature is 40°C to 140°C.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The process route of the present invention can be used to produce 2-substituted tetrafluoropropionyl fluoride compounds. By adjusting the reaction temperature according to actual needs, 2-substituted tetrafluoropropionyl fluoride compounds with different n values can be obtained. When n=2, the process route can be used to prepare perfluoro(8-cyano-5-methyl-3,6-dioxo-1-ene), a raw material for preparing fluorine-containing sulfur monomers.

[0018] 2. The process route of the present invention is short, the process is simple, the operation is easy to control, the entire route does not have relatively harsh reaction conditions, and it is very easy to achieve large-scale industrial production. DETAILED DESCRIPTION

[0019] The present invention will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the present invention are within the scope of protection of the present invention.

[0020] Unless otherwise indicated in specific circumstances, the numerical ranges listed in the present invention include the upper and lower limits, and all integers and fractions within the range, and are not limited to the specific values listed when defining the range.

[0021] 1. A method for preparing a fluorine-containing sulfide point monomer

[0022] The specific synthesis process route is as follows:

[0023]

[0024] Wherein, n≥1; wherein n can be 1, 2, 3 or 4, and all ranges and sub-ranges between the above values.

[0025] When n=2:

[0026]

[0027] The process route of the present invention can be used to produce 2-substituted tetrafluoropropionyl fluoride compounds. By adjusting the reaction temperature according to actual needs, 2-substituted tetrafluoropropionyl fluoride compounds with different n values can be obtained. When n=2, the process route can be used to prepare perfluoro(8-cyano-5-methyl-3,6-dioxo-1-ene), a raw material for preparing fluorine-containing sulfur-site monomers. The process route of the present invention is short, simple, and easy to operate. The entire route does not require relatively harsh reaction conditions, making it very easy to implement large-scale industrial production.

[0028] In some embodiments, the specific steps are as follows:

[0029] Step 1: 2-cyano-2,2-difluoroacetyl fluoride reacts with hexafluoropropylene oxide in the presence of a catalyst at room temperature or below. The resulting reaction product is separated, i.e., the fluorocarbon layer and the organic solvent layer are separated, and the fluorocarbon layer is subjected to vacuum distillation to obtain a 2-substituted tetrafluoropropionyl fluoride compound. The reaction temperature is between -20°C and 20°C. Excessively high or low reaction temperatures will affect the extent of the addition reaction, thereby affecting the amount of compounds with different n values produced. For example, the reaction temperature can be -20°C, -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, etc., as well as all ranges and sub-ranges between the aforementioned values. The amount of hexafluoropropylene oxide absorbed is 1 to 3 equivalents of 2-cyano-2,2-difluoroacetyl fluoride, which can be understood here as a molar ratio of 2-cyano-2,2-difluoroacetyl fluoride to hexafluoropropylene oxide of 1:(1 to 3). For example, the amount of hexafluoropropylene oxide absorbed can be 1 equivalent, 1.2 equivalents, 1.5 equivalents, 1.8 equivalents, 2 equivalents, 2.5 equivalents, 3 equivalents of 2-cyano-2,2-difluoroacetyl fluoride, and all ranges and sub-ranges between the above values. The catalyst is one of potassium fluoride or cesium fluoride. The amount of the catalyst used is 5 mol% to 20 mol% of the amount of 2-cyano-2,2-difluoroacetyl fluoride, calculated as a molar percentage. For example, the amount of the catalyst used can be 5 mol%, 8 mol%, 10 mol%, 12 mol%, 15 mol%, 18 mol%, 20 mol%, and all ranges and sub-ranges between the above values. The reaction solvent is one of acetonitrile, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether. It should be understood that, in embodiments, any of the above ranges can be combined with any other ranges.

[0030] Step 2: Select the product prepared in Step 1, 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride, as a raw material. In the presence of an inorganic base, 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride undergoes a cleavage reaction to obtain a fluorine-containing sulfide monomer, perfluoro(8-cyano-5-methyl-3,6-dioxol-1-ene). In Step 2, the inorganic base is potassium carbonate, sodium carbonate, magnesium carbonate, sodium phosphate, potassium phosphate, or magnesium phosphate. The molar ratio of 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride to the inorganic base is 1:(1-3), for example, the molar ratio of 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride to the inorganic base can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc., and all ranges and sub-ranges between the above values. The reaction temperature is 40° C. to 140° C. For example, the reaction temperature can be 40° C., 50° C., 60° C., 70° C., 80° C., 90° C., 100° C., 110° C., 120° C., 130° C., 140° C., etc., and all ranges and sub-ranges between the above values. It should be understood that in embodiments, any of the above ranges can be combined with any other ranges.

[0031] 2. Examples and Comparative Examples

[0032] Example 1: Synthesis of 2-substituted tetrafluoropropionyl fluoride compounds

[0033] Place 7.6 g (0.05 mol) of CsF powder in a 5 L three-necked flask, with the three ports connected to a vacuum pump, a pressure gauge, and a thermometer. Vacuum the flask and add 50 mL of diethylene glycol dimethyl ether and 61.5 g (0.5 mol) of 2-cyano-2,2-difluoroacetyl fluoride. Turn on magnetic stirring, cool the flask to -10°C, evacuate the flask, and replace the mixture three times with hexafluoropropylene oxide. Then, add hexafluoropropylene oxide to the reaction flask, maintaining the reaction temperature between -20 and 0°C. The reaction is terminated after 170 g of hexafluoropropylene oxide has been absorbed. The reaction mixture is transferred to a separatory funnel, and the fluorocarbon layer is separated and distilled. Depending on the boiling point of the product, 2-substituted tetrafluoropropionyl fluorides with different n values can be separated by vacuum distillation.

[0034] Table 1

[0035] n 1 2 3 4 GC-MS (m / z) 289.0 455.0 621.1 786.9 boiling point 72℃ / 760mmHg 112℃ / 760mmHg 98℃ / 100mmHg 85℃ / 10mmHg Yield (g) 21.6 107.4 34.2 21.5 Purity (GC) 95％ 94％ 95％ 93％

[0036] Example 2: Based on Example 1, adjustments were made except that the reaction temperature in the first step was 0-20° C. Similarly, 2-substituted tetrafluoropropionyl fluoride compounds with different n values were obtained.

[0037] Table 2

[0038] n 1 2 3 4 Yield (g) 52.1 68.2 21.0 13.6 Purity (GC) 95％ 94％ 93％ 95％

[0039] Example 3: Based on Example 1, the reaction solvent in the first step was tetraethylene glycol dimethyl ether. 2-substituted tetrafluoropropionyl fluoride compounds with different n values were also obtained.

[0040] Table 3

[0041] n 1 2 3 4 Yield (g) 23.2 120.0 20.6 16.5 Purity (GC) 95％ 94％ 93％ 96％

[0042] Example 4: Based on Example 1, adjustments were made except that the catalyst in the first step was KF. Similarly, 2-substituted tetrafluoropropionyl fluoride compounds with different n values were obtained.

[0043] Table 4

[0044]

[0045]

[0046] Example 5: Based on Example 1, the method was modified except that the catalyst in the first step was RbF. 2-substituted tetrafluoropropionyl fluoride compounds with different n values were also obtained.

[0047] Table 5

[0048] n 1 2 3 4 Yield (g) 20.5 103.8 21.4 18.7 Purity (GC) 94％ 95％ 93％ 95％

[0049] Example 6: Based on Example 1, the difference is that the catalyst in the first step is KF-SiO2. Similarly, 2-substituted tetrafluoropropionyl fluoride compounds with different n values can be obtained.

[0050] Table 6

[0051] n 1 2 3 4 Yield (g) 25.4 100.2 35.3 21.2 Purity (GC) 95％ 96％ 93％ 94％

[0052] Example 7: Based on Example 1, adjustments were made except that the catalyst in the first step was KF / 18-Crown-6. Similarly, 2-substituted tetrafluoropropionyl fluoride compounds with different n values were obtained.

[0053] Table 7

[0054] n 1 2 3 4 Yield (g) 58.5 81.2 25.6 19.7 Purity (GC) 95％ 96％ 93％ 94％

[0055] Example 8: Based on Example 1, the reaction was adjusted except that the amount of catalyst used was 0.025 mol. 2-substituted tetrafluoropropionyl fluoride compounds with different n values were also obtained.

[0056] Table 8

[0057] n 1 2 3 4 Yield (g) 41.8 87.4 30.5 18.0 Purity (GC) 94％ 95％ 93％ 95％

[0058] Example 9: Based on Example 1, the reaction was adjusted except that the amount of catalyst used was 0.1 mol. 2-substituted tetrafluoropropionyl fluoride compounds with different n values were also obtained.

[0059] Table 9

[0060] n 1 2 3 4 Yield (g) 20.7 115.2 29.3 20.9 Purity (GC) 95％ 94％ 95％ 93％

[0061] Comparing Tables 1 to 9, we can see that:

[0062] (1) The products with different boiling points obtained after separation and purification in Example 1 were tested. According to GC-MS, it can be seen that the obtained products contain compounds with chemical formulas corresponding to when n is 1, 2, 3 and 4, which proves that the method of the present invention can obtain 2-substituted tetrafluoropropionyl fluoride compounds with different n values.

[0063] (2) Different reaction temperature ranges will affect the amount of compounds with different n values produced in the product. When the reaction temperature is controlled at -20 to 0°C, the amount of compounds with n being 2 produced is the largest; when the reaction temperature is controlled at 0 to 20°C, the amount of compounds with n being 1 and n being 2 produced is the largest. Therefore, the reaction temperature can be adjusted as needed to control the amount of compounds with different n values produced in the product.

[0064] (3) The catalysts used in the embodiments of the present invention all have good catalytic effects, but the catalytic effects of each catalyst are slightly different. The catalytic effects are ranked from high to low as CsF, KF-SiO2, RbF, KF / 18-Crown-6, and KF.

[0065] Example 10: Synthesis of perfluoro(8-cyano-5-methyl-3,6-dioxo-1-ene)

[0066] The product with n=2 in Example 1 was selected as the raw material. Potassium carbonate was placed in a reaction flask, and 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride (91.0 g, 0.2 mol) was slowly added dropwise at 40-60°C. The reaction system was then heated to 120-140°C for a cracking reaction. The product was collected and rectified to obtain a product with a bp of 102-105°C / 1 atm and a GC purity of ≥98%.

[0067] After analyzing and testing the product, 19 F NMR (CDCl3, 400MHz): δ=-80.3(3F), -84.17~-85.31(4F), 108.6(2F), 113.3(1F), 121.8(1F), 135.8(1F), 145.0(1F).

[0068] Based on Example 10, improvements were made, and only the amount of potassium carbonate was changed to prepare Examples 11 to 14, as shown in Table 10:

[0069] Table 10

[0070] Example 10 11 12 13 14 Potassium carbonate equivalent 1 1.5 2 2.5 3 Yield (g) 50.7 64.1 71.4 70.3 70.8 Yield (%) 65.8 82.4 91.8 90.3 91.0

[0071] Example 15: Synthesis of perfluoro(8-cyano-5-methyl-3,6-dioxo-1-ene)

[0072] The product with n=2 in Example 1 was selected as the raw material. Other inorganic bases (0.4 mol) were placed in a reaction flask, and 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride (91.0 g, 0.2 mol) was slowly added dropwise at 40-60°C. The reaction system was then heated to 120-140°C for a cleavage reaction. The product was collected and distilled to obtain 67.5 g of the product, with a yield of 86.8% and a GC purity of ≥98%.

[0073] Based on Example 15, improvements were made by changing only the type of inorganic base to prepare Examples 16 to 19, see Table 11.

[0074] Table 11

[0075] Example 15 16 17 18 19 Inorganic base sodium carbonate magnesium carbonate sodium phosphate potassium phosphate magnesium phosphate Yield (g) 67.5 62.1 70.0 72.3 66.8 Yield (%) 86.8 79.8 91.6 92.9 85.9

[0076] It can be seen from Tables 10 to 11 and Examples 10 to 19 that:

[0077] (1) With the increase of potassium carbonate dosage, the yield of the product perfluoro(8-cyano-5-methyl-3,6-dioxo-1-ene) also gradually increases. When the potassium carbonate equivalent is 1, the product yield can reach more than 65.8%, while when the potassium carbonate equivalent is lower than this value, the product yield is too low; when the potassium carbonate equivalent reaches more than 2, the product yield can be maintained at more than 90% and remain stable.

[0078] (2) Using other carbonates as raw materials can also make the product yield reach more than 79%.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the technical solutions. Those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present invention that do not depart from the purpose and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a fluorine-containing sulfide point monomer, characterized in that: The following reaction route is used for preparation: Where n = 1, 2, 3, 4; When n=2:

2. The method for preparing a fluorine-containing sulfide monomer according to claim 1, wherein: The specific steps are as follows: Step 1: 2-cyano-2,2-difluoroacetyl fluoride is reacted with hexafluoropropylene oxide in the presence of a catalyst, and the reaction product is purified to obtain a 2-substituted tetrafluoropropionyl fluoride compound; Step 2: Select the product 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride prepared in step 1 as a raw material. Under the action of an inorganic base, 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride is subjected to a cleavage reaction to obtain a fluorine-containing sulfide point monomer perfluoro(8-cyano-5-methyl-3,6-dioxo-1-ene).

3. The method for preparing a fluorine-containing sulfide monomer according to claim 2, wherein: In step 1, the reaction temperature is -20°C to 20°C; the absorption amount of hexafluoropropylene oxide is 1 to 3 equivalents of 2-cyano-2,2-difluoroacetyl fluoride; the catalyst is one of CsF, RbF, KF, KF-SiO2, and KF / 18-Crown-6, and the amount of the catalyst used is 5 mol% to 20 mol% of the amount of 2-cyano-2,2-difluoroacetyl fluoride calculated by molar percentage.

4. The method for preparing a fluorine-containing sulfide monomer according to claim 2, wherein: In step 1, the reaction solvent is one of acetonitrile, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether.

5. The method for preparing a fluorine-containing sulfide monomer according to claim 2, wherein: In step 2, the inorganic base is potassium carbonate or sodium carbonate; the molar ratio of 2-(2-(2-cyano-1,1,2,2-tetrafluoroethoxy)-1,1,2,3,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionyl fluoride to the inorganic base is 1:(1-3); and the reaction temperature is 40°C to 140°C.

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