Process for the preparation of 2-chloro-1,1,2-trifluoroethyl methyl ether

Abstract

This invention belongs to the field of organic chemical technology, specifically relating to a method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether. The method involves mixing methanol and a catalyst, cooling the mixture to 0-5°C under sealed, ventilated conditions, introducing trifluorochloroethylene, and then heating the mixture to 70-90°C after the introduction of trifluorochloroethylene. After the reaction is complete, the catalyst is separated for reuse, and the reaction solution is purified to obtain pure 2-chloro-1,1,2-trifluoroethyl methyl ether. The catalyst can be a Mg-Al hydrotalcite calcined composite oxide catalyst, a KF / Al₂O₃ supported solid base catalyst, or a bifunctional solid catalyst possessing both basic and metal active sites. The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether provided by this invention meets the comprehensive requirements of environmentally friendly processes, easy catalyst recovery, and high-purity products.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical technology, specifically relating to a method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether. Background Technology

[0002] 2-Chloro-1,1,2-trifluoroethyl methyl ether is an important fluorinated fine chemical with wide applications in pharmaceutical intermediates, organic synthesis, materials science, analytical chemistry, and specialty solvents. Its primary industrial use is as a key intermediate in the synthesis of inhaled fluorinated anesthetics such as enflurane and isoflurane. It can also serve as a fluorinated structural unit in the preparation of complex fluorinated organic compounds, and is used in the synthesis of high-temperature resistant, chemically resistant specialty polymers and high-performance coatings. Furthermore, it can be used as a non-polar reactive solvent for gas chromatography standards and specific organic reactions.

[0003] Currently, the industrial preparation of 2-chloro-1,1,2-trifluoroethyl methyl ether primarily uses 1,1,2-trifluorotrichloroethane (CFC-113) as the starting material, which is obtained through dechlorination, etherification, and purification. This process generates an olefin intermediate through a zinc-mediated dechlorination reaction, which then undergoes nucleophilic addition with methanol under alkaline conditions to obtain the target product. The crude product is collected at the top of the distillation column after separation. However, the 1,1,2-trifluorotrichloroethane used in this process is highly polluting and faces gradual phase-out. The raw material supply and cost risks are significant. Furthermore, the process requires the use of stoichiometric zinc powder for dechlorination, generating wastewater containing heavy metals such as zinc chloride. This wastewater requires complex precipitation and separation treatment to meet discharge standards, significantly increasing the investment and operating costs of environmental protection facilities.

[0004] Besides the traditional processes mentioned above, existing preparation technologies are mainly divided into two categories: strong base-promoted methods and homogeneous catalytic methods. The former uses inorganic strong bases such as sodium hydroxide and potassium hydroxide as reaction promoters to complete the raw material conversion in a polar solvent. This method has a strong alkalinity, which causes severe corrosion to the reaction equipment. The reaction process produces a large amount of waste salt, the post-processing is cumbersome, and the recovery of high-boiling-point solvents is difficult, resulting in poor production economy and environmental protection. The latter uses a homogeneous catalytic system composed of copper salts and organic amines to improve reaction activity and selectivity. This system generally suffers from shortcomings such as difficulty in catalyst separation and recovery, metal ion residues, and complex product purification processes, making it difficult to meet the quality control requirements of continuous industrial production and high-purity products.

[0005] German patent DE3029134A1 discloses a method for preparing haloalliphatic ethers from perhaloethanes via reaction with primary alcohols, secondary alcohols, and inorganic bases under the catalysis of multivalent metal powders, metal salts, organic amines, or mixtures thereof. This method can achieve the synthesis of 2-chloro-1,1,2-trifluoroethyl methyl ether and identifies this compound as an important intermediate in the synthesis of enfluranes. It also records that methanol can form an azeotrope with the target product to simplify the separation process. However, this technology still uses controlled perhaloalkanes as raw materials and employs a homogeneous catalytic system. The catalyst is difficult to separate and recover from the reaction system, easily resulting in metal ion residues. The product purification steps are complex and difficult to adapt to continuous industrial production.

[0006] Chinese patent CN1057753C discloses a method for the phase-transfer catalytic synthesis of fluorinated ethers, which achieves the addition reaction of fluorinated olefins with alcohols through a phase-transfer catalyst and a strong base system, providing a phase-transfer catalytic route for the synthesis of fluorinated ethers. However, this method still relies on a strongly alkaline reaction system, resulting in significant equipment corrosion, large amounts of byproduct waste salt, complex post-processing, and difficult solvent recovery, failing to overcome the inherent defects of traditional strong-base processes. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the problems of difficulty in controlling metal residues, inconvenience in catalyst separation and recovery, and high difficulty in product purification in the existing technology using homogeneous catalytic systems such as cuprous chloride / triethylamine. The present invention provides a method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether, which meets the comprehensive requirements of green raw materials, environmentally friendly process, easy catalyst recovery, high product purity and large-scale production.

[0008] The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to the present invention is as follows: methanol and catalyst are mixed, and the mixture is cooled to 0-5°C under sealed, air-free conditions. Trifluorochloroethylene is then introduced, and after the introduction is completed, the temperature is raised to 70-90°C. After the reaction is completed, the catalyst is separated and reused, and the reaction solution is separated and purified to obtain pure 2-chloro-1,1,2-trifluoroethyl methyl ether. An appropriate amount of inert organic solvent may also be added to the above reaction to improve heat transfer, mass transfer, or the fluidity of the reaction system.

[0009] The inert organic solvent is one or more of hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ether solvents, ester solvents, and nitrile solvents, preferably n-hexane, cyclohexane, toluene, xylene, dichloromethane, or 1,2-dichloroethane.

[0010] The catalyst is a Mg-Al hydrotalcite calcined composite oxide catalyst, a KF / Al2O3 supported solid base catalyst, a Cs2CO3 / SiO2 supported catalyst, a Cu / activated carbon supported catalyst, an amine functionalized resin catalyst, or a bifunctional solid catalyst having both basic and metal active sites.

[0011] The feeding rate of trifluorochloroethylene is 0.5~2.0 g / min.

[0012] The separated catalyst is washed and dried before being reused in the next batch. Specifically, the separated catalyst is preferably washed 2-3 times with methanol to remove adsorbed organic matter and residual reaction liquid. The washed catalyst is then dried at 90-110°C for 8-12 hours and used directly in the next batch reaction. If necessary, the recovered catalyst can be reactivated; the reactivation method involves calcining at 450-500°C in air for 3-6 hours to restore the basic active sites on the catalyst surface.

[0013] The reaction solution is washed with water, dried, distilled, and purified by fractional distillation. After removing the catalyst, the reaction solution is first washed with deionized water 2-3 times, each time for 10-20 minutes, and then dried with anhydrous sodium sulfate or anhydrous magnesium sulfate at 20-25°C for 2-4 hours. After filtration, low-boiling substances are removed by atmospheric distillation, with the top temperature preferably controlled at 62-66°C. Subsequently, fractional distillation is performed, and the main fraction at 68-72°C is collected.

[0014] The molar ratio of methanol to trifluorochloroethylene is 2:1 to 6:1.

[0015] The amount of catalyst used is 5% to 15% of the mass of the raw material trifluorochloroethylene, preferably 10%.

[0016] The preparation method of the Mg-Al hydrotalcite calcined composite oxide catalyst is as follows: A mixed salt solution is prepared by dissolving soluble magnesium salt and soluble aluminum salt, and a precipitant is added under stirring conditions for co-precipitation; the resulting slurry is aged, filtered, washed, and dried to obtain a Mg-Al hydrotalcite precursor; the precursor is then calcined to obtain the Mg-Al hydrotalcite calcined composite oxide catalyst. The soluble magnesium salt can be one or more of magnesium nitrate, magnesium chloride, and magnesium sulfate; the soluble aluminum salt can be one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate; the precipitant can be one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water.

[0017] In the Mg-Al hydrotalcite calcined composite oxide catalyst, the Mg / Al molar ratio is 2:1 to 5:1, more preferably 3:1; it can be prepared by calcining a commercial hydrotalcite precursor. Taking the precursor PURALMG70 as an example, its specific surface area after activation is 180 m². 2 / g or higher, pore volume ≥ 0.2mL / g.

[0018] In the KF / Al2O3 supported catalyst, the commercial product (Sigma-Aldrich, product number 316385) uses 40wt% KF / Al2O3 with a specific surface area of ​​280~390m². 2 / g, with an average pore size of 50~75nm.

[0019] In the Cs2CO3 / SiO2 supported catalyst, the loading is expressed as 10-15% of the total mass of the final catalyst; taking the commercial SiO2 support CARiACTQ-10 as an example, its specific surface area is approximately 300 m². 2 / g, with an average pore size of 10nm and a pore volume of 1.1mL / g.

[0020] In the Cu / activated carbon supported catalyst, the copper loading is expressed as 5-10% of the total mass of the final catalyst. Taking a commercial Cu / activated carbon product as an example, its specific surface area is 185 m². 2 / g, with a particle size of 20×50 mesh.

[0021] After the gas flow is completed, the temperature is raised to 70-90℃, and the reaction time is 6-12 hours.

[0022] The amine-functionalized resin catalyst refers to a solid resin catalyst obtained by introducing amine groups or quaternary ammonium groups onto the backbone of insoluble organic polymers such as cross-linked polystyrene, preferably a hydroxyl-type tertiary amine resin or a strongly basic anion exchange resin.

[0023] The bifunctional solid catalyst that simultaneously possesses basic sites and metal active sites refers to a heterogeneous catalyst formed by simultaneously introducing a metal active component and a basic support / basic site into the same solid material, preferably a Cu-Mg-Al mixed oxide or a Cu-supported catalyst with Mg(Al)O.

[0024] The reaction was carried out under anaerobic conditions.

[0025] Specifically, the method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether is as follows: Methanol is added to a dry, pressure-resistant reactor, along with 5%–15% (by mass) of catalyst (based on the raw material trifluorochloroethylene). After sealing the reactor, the air inside is replaced with nitrogen 2–5 times. The system is then cooled to 0–5°C. Trifluorochloroethylene is slowly introduced into the reactor from a gas cylinder via a gas pipeline, with a methanol to trifluorochloroethylene molar ratio of 2:1–6:1. The addition rate of trifluorochloroethylene is controlled at 0.5–2.0 g / min. After the trifluorochloroethylene addition is complete, the reaction system is heated to 70–90°C and stirred. The reaction is carried out under the specified conditions for 6-12 hours. After the reaction, the solid catalyst is separated by filtration, centrifugation, and sedimentation. The separated catalyst is further washed, dried, and activated before being reused in the next batch of reaction. The liquid phase is first washed 2-3 times with deionized water for 10-20 minutes each time, and then dried with anhydrous sodium sulfate or anhydrous magnesium sulfate at 20-25°C for 2-4 hours. After filtration, low-boiling substances are removed by atmospheric distillation, with the top temperature preferably controlled at 62-66°C. Subsequently, the main fraction at 68-72°C is collected to obtain the 2-chloro-1,1,2-trifluoroethyl methyl ether product. This invention achieves a purity of over 99.9% through multiple distillations.

[0026] In this invention, under the catalysis of a solid catalyst, the hydroxyl group (-OH) in methanol (CH3OH) undergoes a nucleophilic addition reaction with trifluorochloroethylene (CF2=CFCl). The carbon-carbon double bond in the trifluorochloroethylene molecule is opened, and the hydroxyl group of methanol nucleophilically attacks the electron-deficient carbon atom on the double bond. Simultaneously, the electron cloud on the double bond is transferred, ultimately forming 2-chloro-1,1,2-trifluoroethyl methyl ether (CF2ClCF(OCH3)). The solid catalyst activates the hydroxyl group of methanol, enhancing its nucleophilicity, while simultaneously adsorbing trifluorochloroethylene molecules, lowering the activation energy of the reaction, and promoting efficient and directional reaction. If a bifunctional solid catalyst is used, its basic sites can activate the hydroxyl group of methanol, and its metal active sites can adsorb and activate the carbon-carbon double bond of trifluorochloroethylene, further improving the reaction rate and selectivity, and reducing the formation of byproducts (such as dimers and polymers).

[0027] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention uses a solid catalyst to replace the traditional homogeneous catalytic system, which completely solves the problems of difficult control of metal residue and inconvenient separation and recovery of catalyst in the prior art. The solid catalyst can be separated by simple filtration, and can be reused after washing, drying and activation. After being reused 5 to 8 times, the catalytic efficiency is still maintained at more than 85% of the initial efficiency, which greatly reduces the cost of catalyst. At the same time, it avoids the contamination of the product by the homogeneous catalyst, which is conducive to product purification.

[0028] (2) The process of this invention is environmentally friendly and the raw materials are green. The reaction raw materials are methanol and trifluorochloroethylene. No toxic or harmful raw materials are added. There is no obvious discharge of waste during the reaction process. The washing solvent can be recycled and reused. The small amount of low-boiling point impurities generated during distillation and rectification can be centrally treated, which meets the requirements of green chemical production. At the same time, the reaction and purification process parameters are optimized, and the product purity is high, which meets the product quality requirements of large-scale production.

[0029] (3) The reaction conditions of this invention are mild, no high temperature and high pressure equipment is required, the equipment investment cost is low, the operation is simple, the reaction rate is easy to control, the by-product content is less than 0.5%, and the conversion rate and reaction selectivity of trifluorochloroethylene are improved. Attached Figure Description

[0030] Figure 1 The HNMR spectrum of 2-chloro-1,1,2-trifluoroethyl methyl ether prepared in Example 1.

[0031] Figure 2 The gas chromatogram of 2-chloro-1,1,2-trifluoroethyl methyl ether prepared in Example 1. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments.

[0033] The specific preparation process of the Mg-Al hydrotalcite calcined composite oxide catalyst used below is as follows: 15.38g of Mg(NO3)2•6H2O and 7.5g of Al(NO3)3•9H2O were weighed and dissolved in 100mL of deionized water to obtain mixed solution A. 8g of sodium hydroxide and 5.3g of sodium carbonate were weighed and dissolved in 100mL of deionized water to obtain mixed solution B. Under stirring conditions, the metal mixed solution A and the precipitate solution B were simultaneously added dropwise to the reactor, controlling the system temperature at 25℃ and the pH at 9. After adding 0.5~10.5, continue stirring for 1 hour. Then, heat the slurry to 80℃ and age it for 8 hours. After aging, filter it and wash the obtained solid with deionized water until the pH of the washing solution is close to neutral. Then, dry the washed solid at 120℃ for 8 hours to obtain the Mg-Al hydrotalcite precursor. Place the obtained precursor in a calcination furnace and calcinate it at 500℃ in an air atmosphere for 6 hours. Finally, cool, crush, and sieve the calcined sample to obtain the Mg-Al hydrotalcite calcined composite oxide catalyst.

[0034] Preparation of Cs2CO3 / SiO2 supported catalyst: 20.0 g of silica spherical support was placed in a rotary impregnation device. 22.78 g of 17 wt% cesium carbonate aqueous solution was also taken. Under room temperature conditions, the cesium carbonate aqueous solution was uniformly added to the silica support by spraying while the support was rotated for 10 min for impregnation. After impregnation, the sample was allowed to stand at room temperature for 1 h, and then dried at 120 °C for 6 h. After drying, it was further calcined at 500 °C for 6 h to obtain a 16 wt% Cs2CO3 / SiO2 supported catalyst.

[0035] A bifunctional solid catalyst (Cu-Mg-Al mixed oxide) possessing both basic and metallic active sites: 15.38 g of magnesium nitrate hexahydrate, 7.50 g of aluminum nitrate nonahydrate, and 0.69 g of copper nitrate trihydrate were dissolved in deionized water and the volume was adjusted to 100 mL to obtain metal mixture A; 8.0 g of sodium hydroxide and 5.3 g of sodium carbonate were dissolved in deionized water and the volume was adjusted to 100 mL to obtain precipitate B. Under stirring conditions, metal mixture A and precipitate B were simultaneously added dropwise to the reactor, with the system temperature controlled at 25℃ and pH at 9.5~10.5. After the addition was completed, stirring was continued for 1 hour. Then, the slurry was heated to 80℃ and aged for 8 hours. After aging, it was filtered, and the obtained solid was washed with deionized water until the pH of the washing solution was close to neutral. Then, the washed solid was dried at 120℃ for 8 hours to obtain Cu-Mg-Al hydrotalcite precursor. The obtained precursor was placed in a calcination furnace and heated to 500℃ in an air atmosphere for 6 hours. Finally, the calcined sample was cooled, pulverized, and sieved to obtain Cu-Mg-Al mixed oxide, in which Cu provides metal active sites and Mg-Al mixed oxide provides basic sites.

[0036] KF / Al2O3 supported solid base catalyst was purchased from Sigma-Aldrich, 316385, 40 wt.% KF onalumina.

[0037] The amine-functionalized resin catalyst was purchased from Sigma, Amberlite IRN78 OH.

[0038] Example 1 The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to the present invention is as follows: 128g of methanol, 38.4g of hexane (an organic inert solvent), and 11.65g of Mg-Al hydrotalcite calcined composite oxide catalyst are added to a dry, pressure-resistant reactor. After sealing the reactor, the air inside is replaced with nitrogen three times. The system is then cooled to 0-5°C. Trifluorochloroethylene is slowly introduced into the reactor from a gas cylinder via a gas pipeline, with the feeding rate controlled at 1.0g / min. The total amount of trifluorochloroethylene introduced is 116.5g. After the trifluorochloroethylene is added, the reaction mixture is... The temperature was raised to 90℃ and the reaction was carried out for 8 hours under stirring. After the reaction, the solid catalyst was separated by filtration, centrifugation, and sedimentation. The liquid phase was first washed three times with deionized water for 15 minutes each time, and then dried with anhydrous sodium sulfate at 20℃ for 3 hours. After filtration, low-boiling substances were removed by atmospheric distillation, with the top temperature preferably controlled at 62-66℃. Subsequently, the main fraction at 68-72℃ was collected, and 145.2 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was finally obtained, with a yield of 98.9% and a purity of 99.99%. The ¹H NMR spectrum of the prepared 2-chloro-1,1,2-trifluoroethyl methyl ether product is shown below. Figure 1 As shown, its gas chromatogram is as follows: Figure 2 As shown.

[0039] After separating the solid catalyst, the following treatment was performed: washing it three times with methanol, drying it at 110°C for 12 hours, calcining it at 500°C for 4 hours in air for activation, and then reusing it for the next batch of reaction.

[0040] The activated catalyst was then reintroduced into the same preparation steps (the same process was repeated 5 times) for catalysis, and the catalytic effect is shown in Table 1.

[0041] Example 2 Except for the absence of the inert organic solvent n-hexane, the other conditions were the same as in Example 1, and a total of 141.5 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was finally obtained, with a yield of 96.4% and a purity of 99.98%.

[0042] Example 3 The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to the present invention is as follows: 128g of methanol, 38.4g of hexane (an organic inert solvent), and 11.65g of KF / Al2O3 supported solid base catalyst are added to a dry, pressure-resistant reactor. The amount of catalyst is 10% of the mass of the raw material trifluorochloroethylene. After sealing the reactor, the air inside the reactor is replaced with nitrogen three times. Subsequently, the system is cooled to 0-5°C. Trifluorochloroethylene is slowly introduced into the reactor from a gas cylinder via a gas pipeline, controlling the feeding rate at 1.0g / min. The total amount of trifluorochloroethylene introduced is 116.5g. After the trifluorochloroethylene is added, the reaction system is heated to 90°C. The reaction was carried out under stirring for 8 hours. After the reaction, the solid catalyst was separated by filtration, centrifugation, and sedimentation. The separated catalyst was further washed, dried, and activated before being reused in the next batch of reaction. The liquid phase was first washed twice with deionized water for 20 minutes each time, and then dried with anhydrous magnesium sulfate at 25°C for 2 hours. After filtration, low-boiling substances were removed by atmospheric distillation, with the top temperature preferably controlled at 62-66°C. Then, the distillation was carried out and the main fraction at 68-72°C was collected. Finally, 137.1 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was obtained, with a yield of 93.4% and a purity of 99.79%.

[0043] Example 4 The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to the present invention is as follows: 128g of methanol, 38.4g of hexane (an organic inert solvent), and 11.65g of Cs₂CO₃ / SiO₂ supported catalyst are added to a dry, pressure-resistant reactor. The amount of catalyst is 10% of the mass of the raw material trifluorochloroethylene. After sealing the reactor, the air inside the reactor is replaced with nitrogen three times. Then, the system is cooled to 0-5°C. Trifluorochloroethylene is slowly introduced into the reactor from a gas cylinder via a gas pipeline, controlling the feeding rate at 1.0g / min. The total amount of trifluorochloroethylene introduced is 116.5g. After the trifluorochloroethylene is added, the reaction system is heated to 90°C and reacted under stirring for 8 hours. After the reaction was completed, the solid catalyst was separated by filtration, centrifugation, and sedimentation. The separated catalyst was further washed, dried, and activated before being reused in the next batch of reaction. The liquid phase was first washed three times with deionized water for 15 minutes each time, and then dried with anhydrous sodium sulfate at 25°C for 3 hours. After filtration, low-boiling substances were removed by atmospheric distillation, with the top temperature preferably controlled at 62-66°C. Then, the distillation was carried out and the main fraction at 68-72°C was collected. Finally, 134.1 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was obtained, with a yield of 91.3% and a purity of 99.85%.

[0044] Example 5 The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to this invention is as follows: 128g of methanol, 38.4g of hexane (an organic inert solvent), and 11.65g of amine-functionalized resin catalyst are added to a dry, pressure-resistant reactor. After sealing the reactor, the air inside is replaced with nitrogen three times. The system is then cooled to 0-5°C. Trifluorochloroethylene is slowly introduced into the reactor from a gas cylinder via a gas pipeline, with the feeding rate controlled at 1.0g / min. The total amount of trifluorochloroethylene introduced is 116.5g. After the trifluorochloroethylene is added, the reaction system is heated to 90°C and reacted under stirring for 8 hours. After the reaction was completed, the solid catalyst was separated by filtration, centrifugation, and sedimentation. The separated catalyst was further washed, dried, and activated before being reused in the next batch of reaction. The liquid phase was first washed three times with deionized water for 15 minutes each time, and then dried with anhydrous magnesium sulfate at 25°C for 3 hours. After filtration, low-boiling substances were removed by atmospheric distillation, with the top temperature preferably controlled at 62-66°C. Then, the distillation was carried out and the main fraction at 68-72°C was collected. Finally, 135.2 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was obtained, with a yield of 92.1% and a purity of 99.88%.

[0045] Example 6 The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to the present invention is as follows: 128g of methanol, 38.4g of hexane (an organic inert solvent), and 11.65g of Cu-Mg-Al mixed oxide are added to a dry, pressure-resistant reactor. After sealing the reactor, the air inside is replaced with nitrogen three times. The system is then cooled to 0-5°C. Trifluorochloroethylene is slowly introduced into the reactor from a gas cylinder via a gas pipeline at a controlled feeding rate of 1.0g / min, with a total amount of 116.5g of trifluorochloroethylene introduced. After the trifluorochloroethylene is added, the reaction system is heated to 90°C and reacted for 8 hours under stirring. After the reaction was completed, the solid catalyst was separated by filtration, centrifugation, and sedimentation. The separated catalyst was further washed, dried, and activated before being reused in the next batch of reaction. The liquid phase was first washed three times with deionized water for 15 minutes each time, and then dried with anhydrous sodium sulfate at 25°C for 3 hours. After filtration, low-boiling substances were removed by atmospheric distillation, with the top temperature preferably controlled at 62-66°C. Subsequently, the distillation was carried out and the main fraction at 68-72°C was collected. Finally, 139.2 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was obtained, with a yield of 94.8% and a purity of 99.89%.

[0046] Example 7 Except for adjusting the molar ratio of methanol to trifluorochloroethylene to 2:1, the other conditions were the same as in Example 1. The mass of methanol was 64 g, and the mass of trifluorochloroethylene was 116.5 g. After the reaction, the product was processed in the same way as in Example 1, finally yielding 137.4 g of 2-chloro-1,1,2-trifluoroethyl methyl ether, with a yield of 93.6% and a purity of 99.90%.

[0047] Example 8 Except for adjusting the molar ratio of methanol to trifluorochloroethylene to 6:1, the other conditions were the same as in Example 1. The mass of methanol was 192 g, and the mass of trifluorochloroethylene was 116.5 g. After the reaction, the product was processed in the same way as in Example 1, finally yielding 135.5 g of 2-chloro-1,1,2-trifluoroethyl methyl ether, with a yield of 92.3% and a purity of 99.88%.

[0048] Example 9 Except for adjusting the influent rate of trifluorochloroethylene to 0.5 g / min, the other conditions were exactly the same as in Example 1. After the reaction was completed, the product was processed in the same way as in Example 1, and 133.9 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was finally obtained, with a yield of 91.2% and a purity of 99.79%.

[0049] Example 10 Except for adjusting the influent rate of trifluorochloroethylene to 1.5 g / min, the other conditions were exactly the same as in Example 1. After the reaction was completed, the product was processed in the same way as in Example 1, and 136.2 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was finally obtained, with a yield of 92.8% and a purity of 99.85%.

[0050] Example 11 Except for adjusting the influent rate of trifluorochloroethylene to 2.0 g / min, the other conditions were exactly the same as in Example 1. After the reaction was completed, the product was processed in the same way as in Example 1, and 134.9 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was finally obtained, with a yield of 91.9% and a purity of 99.83%.

[0051] Example 12 Except for changing the amount of solid catalyst to 5.825 g (5% of the mass of trifluorochloroethylene), the other conditions were exactly the same as in Example 1. After the reaction was completed, the product was processed in the same way as in Example 1, and 140.5 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was finally obtained, with a yield of 95.7% and a purity of 99.99%.

[0052] Example 13 Except for changing the amount of solid catalyst to 17.475 g (15% of the mass of trifluorochloroethylene), the other conditions were exactly the same as in Example 1. After the reaction was completed, the product was processed in the same way as in Example 1, and finally 135.9 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was obtained, with a yield of 92.6% and a purity of 99.90%.

[0053] Comparative Example 1 Except for the absence of the solid catalyst used in Example 1, all other conditions were identical to those in Example 1. After the reaction was complete, it was found that the raw materials were completely remaining, and no product was formed.

[0054] Comparative Example 2 Except for replacing trifluorochloroethylene in Example 1 with 1-chloro-3,3,3-trifluoropropene (135g), the other raw material types, methanol dosage, solid catalyst dosage, feeding method, reaction temperature, reaction time, and post-treatment steps were the same as in Example 1. Finally, 56.6g of 1-methoxy-3,3,3-trifluoroprop-1-ene was obtained, which can be one or more of the E / Z isomers, with a yield of 44.9%. The results show that the reaction behavior of different chlorinated and fluorinated olefins in the catalytic system of this invention varies significantly. Trifluorochloroethylene reacts more effectively with methanol to form the target product, while other chlorinated and fluorinated olefins are more likely to generate byproducts with different skeletons or other addition products. Therefore, the selection of trifluorochloroethylene as a raw material in this invention has significant specificity and advantages.

[0055] Comparative Example 3 A method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether: 128g of methanol and 40g of sodium hydroxide are added to a dry, pressure-resistant reactor. After sealing the reactor, the air inside is replaced with nitrogen three times. The mixture is stirred at 45°C for 3 hours until a homogeneous alkaline methanol system is formed. The system is then cooled to 0-5°C. Trifluorochloroethylene is slowly introduced into the reactor through a gas pipeline from a steel cylinder at a rate of 1.0g / min, with a total amount of 116.5g of trifluorochloroethylene introduced. After the trifluorochloroethylene is added, the reaction system is heated to 45°C and reacted for 3 hours under stirring. After the reaction, the alkali and its by-product salts dissolve or disperse in the reaction system, making direct separation by simple physical methods difficult. Multiple post-processing steps, including neutralization, washing, layering, drying, and distillation, are required, which is cumbersome and easily generates a large amount of waste liquid and waste salt. After processing, 106.3 g of 2-chloro-1,1,2-trifluoroethyl methyl ether was finally obtained, with a yield of 72.4%.

[0056] Comparative Example 4 A method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether: 4.6 g of sodium was dissolved in 75 mL of methanol, and 0.5 g of CuCl2 was added, followed by 11.65 g of trifluorochloroethylene. No obvious immediate reaction was observed. When 0.5 g of triethanolamine was added, the reaction became exothermic, and a precipitate formed. After the reaction weakened, water was added to obtain 10.164 g of product, with a yield of 68.4%. Compared with the examples, it can be seen that although the traditional copper salt / amine homogeneous catalytic system can promote the reaction, the catalytic components dissolve or disperse in the reaction solution after the reaction, making direct separation by simple filtration difficult. Additional copper removal and multi-step purification are usually required, making post-processing cumbersome and posing a problem of metal residue control. In contrast, this invention uses a solid catalyst, and the catalytic components can be directly separated and recovered by filtration or centrifugation after the reaction, eliminating the need for copper removal steps, which helps reduce the burden of post-processing and avoids the risk of metal residue.

[0057] The conversion rate of trifluorochloroethylene (CTFE), as well as the selectivity and yield of 2-chloro-1,1,2-trifluoroethyl methyl ether in the preparation of 2-chloro-1,1,2-trifluoroethyl methyl ether products in the above examples and comparative examples, are shown in Table 2.

[0058] Table 1. Results of catalyst reuse in Example 1

[0059] Table 2. Results of products prepared in the examples and comparative examples.

Claims

1. A method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether, characterized in that: Methanol and catalyst were mixed, and the mixture was cooled to 0-5°C under sealed conditions to remove air. Trifluorochloroethylene was then introduced, and the temperature was raised to 70-90°C after the introduction was completed. After the reaction was completed, the catalyst was separated and reused, and the reaction solution was separated and purified to obtain pure 2-chloro-1,1,2-trifluoroethyl methyl ether. The catalyst is a Mg-Al hydrotalcite calcined composite oxide catalyst, a KF / Al2O3 supported solid base catalyst, a Cs2CO3 / SiO2 supported catalyst, a Cu / activated carbon supported catalyst, an amine functionalized resin catalyst, or a bifunctional solid catalyst with both basic and metal active sites.

2. The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to claim 1, characterized in that: The feeding rate of trifluorochloroethylene is 0.5~2.0 g / min.

3. The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to claim 1, characterized in that: The separated catalyst is washed and dried before being reused in the next batch.

4. The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to claim 1, characterized in that: The reaction solution was washed with water, dried, distilled, and purified by distillation.

5. The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to claim 1, characterized in that: The molar ratio of methanol to trifluorochloroethylene is 2:1 to 6:

1.

6. The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to claim 2, characterized in that: The amount of catalyst used is 5% to 15% of the mass of trifluorochloroethylene.

7. The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to claim 1, characterized in that: The preparation method of Mg-Al hydrotalcite calcined composite oxide catalyst is as follows: soluble magnesium salt and soluble aluminum salt are prepared into a mixed salt solution, and a precipitant is added under stirring conditions for co-precipitation; The obtained slurry was aged, filtered, washed, and dried to obtain Mg-Al hydrotalcite precursor; The precursor was then calcined to obtain a Mg-Al hydrotalcite calcined composite oxide catalyst.

8. The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to claim 1, characterized in that: After the gas flow is completed, the temperature is raised to 70-90℃, and the reaction time is 6-12 hours.

9. The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to claim 1, characterized in that: Add n-hexane, cyclohexane, toluene, xylene, dichloromethane, or 1,2-dichloroethane to the reaction.

10. The method for preparing 2-chloro-1,1,2-trifluoroethyl methyl ether according to claim 1, characterized in that: The reaction was carried out under anaerobic conditions.

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