A method for preparing highly selective fluoroolefins

Abstract

This invention proposes a method for preparing highly selective fluoroolefins, characterized in that the fluoroolefin reactant has the following structural formula: R f1 R f2 R f3 Selected from one of -F, -CF3, and -CH3; R f4 The product is selected from one of -N(CF3)2, -COF, CF3CF2OCF2CF2-, -OCF3, -OCF2CF3, and -OCF2CF2CF3, CF3OCF2CF2-; the preparation method is carried out according to the following steps: the reactants are reacted under the action of a catalyst to obtain fluoroolefins. The product prepared in this application has high purity.

Description

Technical Field

[0001] This invention relates to a method for preparing highly selective fluoroolefins. Background Technology

[0002] Fluoroolefins possess certain chemical reactivity, capable of undergoing addition or polymerization reactions to derive a variety of fluorinated organic compounds. Furthermore, fluorinated olefins exhibit low surface tension, good electrochemical performance, and environmental compatibility (ODP = 0, low GWP value), making them widely used in surfactants, pharmaceutical intermediates, and heat transfer media.

[0003] 1. Catalytic synthesis of fluoroolefins has been reported, but the product contains multiple isomers with small differences in boiling points, making separation difficult.

[0004] 2. Alkali metal fluorides have low solubility in organic solvents, and the amount dissolved is insufficient to reach the minimum dosage required for catalysis. Crown ether co-catalysts are usually added, as crown ethers form complexes with metal cations through electrostatic attraction, increasing solubility. The fluorinated amine catalyst used in this scheme has sufficient solubility within a limited solvent range to catalyze the reaction, eliminating the need for a co-catalyst. For example, the patent titled "A Method for Preparing and Applying Perfluoroolefin Oligomers," patent number CN 113816824, requires a phase transfer catalyst.

[0005] 3. During the synthesis of fluoroolefins, dimer and polymer products coexist, leading to a decrease in raw material utilization. For example, the patent title "A Method for Preparing and Applying Perfluoroolefin Oligomers" (patent number CN 113816824) produces a mixture of products. Summary of the Invention

[0006] This invention provides a method for preparing highly selective fluoroolefins, solving the technical problem of preparing a method for fluoroolefins with high purity.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for preparing highly selective fluoroolefins, wherein the fluoroolefin reactants have the following structural formula: Where R f1 R f2 R f3 Selected from -F, -CF3, and -CH3; R f4 Selected from -N(CF3)2, One of -COF, CF3CF2OCF2CF2-, -OCF3, -OCF2CF3, and -OCF2CF2CF3, CF3OCF2CF2-;

[0009] The preparation method is carried out according to the following steps: the catalyst is added to an organic solvent, nitrogen gas is introduced to fully replace the solvent and the mixture is stirred. The reactants are introduced at a temperature of 20-100℃ and a pressure of 0.5 MPa and reacted for 2 hours. The mixture is then cooled to room temperature. The catalyst liquid and the product are separated using a separatory funnel. The upper layer is the solvent and the lower layer is the target product. The target product is collected, and the solvent and catalyst in the target product are washed away with deionized water. After drying, fluoroolefins are obtained.

[0010] The catalyst is one or more of tetramethylammonium fluoride, Selectfluor, tetrabutylammonium fluoride, tetraethylammonium fluoride, tetraethylammonium fluoride trihydrofluoride, and tetrabutylammonium dihydrofluoride.

[0011] The organic solvent is one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, acetonitrile, and N,N-dimethylformamide;

[0012] The reactants are short-chain fluoroethers or mixtures of short-chain fluoroethers and non-aromatic amines.

[0013] The temperature is 30–80°C.

[0014] The reactants are short-chain fluoroethers or non-aromatic amines containing one or more of the functional groups -N(CF3)2, -OCF3, -OCF2CF3 and -OCF2CF2CF3.

[0015] The solvent accounts for 10%-90 wt% of the reactants, and the catalyst accounts for 0.01%-15% of the molar weight of the reactants.

[0016] The catalyst is one or both of tetrabutylammonium fluoride and tetraethylammonium fluoride.

[0017] The invention has the following beneficial technical effects:

[0018] 1. Nitrogen-containing ions form complexes with fluoroolefin ions, lowering the transition state energy and providing good stabilization for the internal olefin transition state. Furthermore, using feedstocks within a defined range results in internal olefins with more substituents than terminal olefins, further enhancing their stability. Therefore, the catalyst exhibits high selectivity in catalyzing the formation of perfluorinated internal olefins without the formation of terminal olefin isomers.

[0019] 2. Within the specified range, the product generated from the raw materials is a dimer. Because the aforementioned dimer contains a large number of olefin substituents, it has significant steric hindrance, which hinders the dimer carbanion from further attacking the olefin double bond to generate a polymer.

[0020] 3. Fluorinated amine catalysts have good solubility and can achieve good catalytic effects without the need for co-catalysts to increase solubility. Alkali metal fluorides have low solubility in organic solvents, and the amount dissolved cannot reach the minimum dosage required for catalysis. Crown ether co-catalysts are usually added. Crown ethers form complexes with metal cations through electrostatic attraction, thereby increasing solubility.

[0021] 4. The reaction conditions are mild, and a one-pot continuous reaction can be carried out; the equipment is highly versatile and can be carried out in any suitable equipment, such as stirred pressure reactors, tubular reactors, microchannel reactors, etc. Detailed Implementation

[0022] The invention will be further illustrated below with specific examples.

[0023] Example 1

[0024] Add 50 ml of a 0.05 mol / L tetra-n-butylammonium difluoride hydrofluoric acid solution in acetonitrile to a high-pressure reactor. Stir at 400 rpm and pressurize with nitrogen to 0.5 MPa to ensure a nitrogen atmosphere. After heating to 35°C, adjust the pressure to 0.5 MPa and continuously introduce the reaction gas trifluoromethyl trifluorovinyl ether for 2 hours. The reaction is exothermic during the introduction process and requires appropriate cooling. After the reaction is complete, cool to room temperature and separate the layers using a separatory funnel. The upper layer is the solvent, and the lower layer is the target product. Wash with deionized water to remove the solvent and catalyst. After separation and drying, the target product is obtained with a yield of 91% and its molecular structure is [insert molecular structure here].

[0025] Example 2

[0026] Add 50 ml of a 0.01 mol / L tetrabutylammonium fluoride tetrahydrofuran solution to a high-pressure reactor, stir at 400 rpm, and pressurize to 0.5 MPa with nitrogen to ensure a complete nitrogen atmosphere. After heating to 50°C, adjust the pressure to 0.5 MPa and continuously purge with the reaction gas perfluoroethyl vinyl ether for 2 hours. The reaction is exothermic during the purging process and requires appropriate cooling. After the reaction is complete, cool to room temperature and separate the layers using a separatory funnel. The upper layer is the solvent, and the lower layer is the target product. Wash with deionized water to remove the solvent and catalyst. After separation and drying, the target product is obtained with a yield of 92% and its molecular structure is [insert molecular structure here].

[0027] Example 3

[0028] Add 50 ml of a 0.05 mol / L tetraethylammonium fluoride tetrahydrofuran solution to a high-pressure reactor, stir at 400 rpm, and pressurize to 0.5 MPa with nitrogen to ensure a nitrogen atmosphere. After heating to 65°C, continuously introduce the reaction gas perfluoropropyl vinyl ether stored in a constant-temperature tank, adjusting the pressure to 0.5 MPa for 2 hours. The reaction is exothermic during the introduction process and requires appropriate cooling. After the reaction is complete, cool to room temperature and separate the layers using a separatory funnel. The upper layer is the solvent, and the lower layer is the target product. Wash with deionized water to remove the solvent and catalyst. After separation and drying, the target product is obtained with a yield of 96% and its molecular structure is [insert molecular structure here].

[0029] Example 4

[0030] Add 50 ml of a 0.05 mol / L tetraethylammonium fluoride tetrahydrofuran solution to a high-pressure reactor, stir at 400 rpm, and pressurize to 0.5 MPa with nitrogen to ensure a nitrogen atmosphere. After heating to 55°C, simultaneously and continuously introduce the reaction gases perfluoropropyl vinyl ether and 1,2,2-trifluoro-N,N-bis(trifluoromethyl)ethyleneamine stored in a constant-temperature storage tank, adjusting the pressure to 0.5 MPa for 2 hours. The reaction is exothermic during the introduction process and requires appropriate cooling. After the reaction is complete, cool to room temperature and separate the layers using a separatory funnel. The upper layer is the solvent, and the lower layer is the target product. Wash with deionized water to remove the solvent and catalyst. After separation and drying, the target product is obtained with a yield of 89% and its molecular structure is [insert molecular structure here].

[0031] Comparative Example 1

[0032] The other conditions were the same as in Example 2, except that the catalyst was replaced with a 0.01 mol / L KF tetrahydrofuran solution, and no product was generated.

[0033] Comparative Example 2

[0034] The other conditions were the same as in Example 2, except that the catalyst was replaced with a 0.01 mol / L KF main catalyst and a 0.01 mol / L tetrahydrofuran solution of crown ether as the co-catalyst. The product yield was 25%.

[0035] Comparative Example 3

[0036] The other conditions were the same as in Example 2, except that the main catalyst was replaced with 0.01 mol / L CsF and the co-catalyst was a 0.01 mol / L tetrahydrofuran solution of crown ether. The product yield was 45%.

[0037] Summarize:

[0038] (1) Comparative Example 1 shows that catalyst KF alone cannot catalyze the reaction of perfluoroethyl vinyl ether.

[0039] Comparative Examples 1 and 2 demonstrate that KF can catalyze the reaction after the addition of the co-catalyst crown ether, but its catalytic effect is worse than that of the tetrabutylammonium fluoride catalyst in Example 2.

[0040] (2) Comparison data from Comparative Example 1, Comparative Example 3 and Example 2 show that the catalytic effects of KF and CsF are weaker than those of the catalyst tetrabutylammonium fluoride in Example 2.

Claims

1. A process for the preparation of a highly selective fluorolefin dimer product, characterized by, The structure of the reactant is wherein R f1 , R f2 , R f3 is selected from one of -F, -CF3, and -CH3; R f4 is selected from one of -N(CF3)2, CF3CF2OCF2CF2-, -OCF3, -OCF2CF3, and -OCF2CF2CF3, CF3OCF2CF2-. The preparation method is carried out according to the following steps, The catalyst is added into the organic solvent, nitrogen is flushed in for sufficient replacement and stirring, the reaction material is introduced under the condition that the temperature is 20-100 DEG C and the pressure is 0.5 Mpa, reaction is carried out for 2h, it is reduced to room temperature, the catalyst liquid is separated from the product by using a separating funnel, the obtained upper layer is solvent, the lower layer is target product, the target product is collected, the solvent and catalyst in the target product are washed away by using deionized water, after drying, the fluoroolefin dimerization product is obtained; The catalyst is one or several of tetramethylammonium fluoride, tetrabutylammonium fluoride, tetraethylammonium fluoride, tetraethylammonium fluoride trihydrofluoride and tetrabutyl dihydro trifluoride ammonium; The organic solvent is one or several of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, acetonitrile and N, N-dimethylformamide.

2. The process for the preparation of high selectivity fluorooefine dimerization products as claimed in claim 1 wherein, The temperature is 30-80 DEG C.

3. The process for the preparation of high selectivity fluorooefine dimerization product as claimed in claim 1 wherein, the process is carried out at a temperature in the range of 50- 70°C. The solvent accounts for 10%-90 wt% of the mass of the reaction material, and the catalyst accounts for 0.01%-15% of the molar amount of the reaction material.

4. The process for the preparation of high selectivity fluorooefine dimerization products as claimed in claim 1 wherein, The catalyst is one or both of tetrabutylammonium fluoride and tetraethylammonium fluoride.

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