Method for preparing methyl trifluoromethyl ether
By using trifluoromethyl fluoroformate to replace carbonyl fluoride, and reacting it with alkali metal fluorides and phase transfer catalysts to prepare methyl trifluoromethyl ether, the problems of raw material toxicity and high cost in the prior art are solved, and safe and low-cost industrial production is realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 漳平市九鼎泰天科技有限公司
- Filing Date
- 2026-01-30
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies make it difficult to achieve the industrial production of methyl trifluoromethyl ether, especially due to the high toxicity and cost of the raw material, fluorocarbonyl fluoride, as well as the harsh reaction conditions and high equipment requirements.
Methyltrifluoromethyl ether is prepared by reacting trifluoromethyl fluoroformate with alkali metal fluorides and/or tetramethylammonium fluoride in the presence of a phase transfer catalyst and a methylating agent, thus avoiding the use of highly toxic raw materials and reducing reaction pressure.
This method enables the safe and low-cost preparation of methyl trifluoromethyl ether, simplifies the process, reduces equipment requirements, and improves product separation efficiency.
Abstract
Description
Technical Field
[0001] This invention relates to the field of fluorochemical technology, and in particular to a method for preparing methyl trifluoromethyl ether. Background Technology
[0002] Hydrofluoroether (CF3OCH3) (methyl trifluoromethyl ether, also known as HFE-143a, HFE-143m, etc.) is a novel refrigerant that can replace CFCs, HCFCs, and HFCs. Its GWP100 is only 680, far lower than commonly used refrigerants CFC-12 and HFC-134a. Studies show that the heat transfer coefficients of HFE-143m during boiling and condensation are very close to those of HFC-134a. HFE-143m operates at lower pressures than HFC-134a. Under isentropic compression conditions, its cooling capacity and COP increase by 2.9% and 3.6% respectively. Under a fixed compressor outlet superheat (25°C), its cooling capacity and COP increase by 2.9% and 16.6% respectively, making it a potential replacement for HFC-134a. In recent years, as concerns have grown about the high potential risks to the environment and human health posed by the continued emissions of short-chain PFAS, especially trifluoroacetic acid (TFA), research has begun on next-generation products to replace the widely used HFO-1234yf (a substance that raises concerns due to its atmospheric decomposition product of TFA). Since HFE-143m does not produce trifluoroacetic acid upon atmospheric degradation, it holds significant promise as a potential alternative to HFO-1234yf.
[0003] Numerous methods for synthesizing HFE-143m have been reported. These mainly include: direct fluorination and electrochemical fluorination of ether compounds; alkylation of fluorinated alcohols; and alkylation of acyl fluorides.
[0004] Direct fluorination can be carried out using high-valent metal fluorides (such as SbF5, CoF3, MnF3, etc.), but the fluorinating agents are expensive and not suitable for industrial production; F2, fluorinated halogens and other fluorinating agents can also be used, but these fluorinating agents have poor selectivity.
[0005] Electrolytic fluorination can be used to prepare many organofluorine compounds with functional groups, but the yield of perfluoroalkyl ethers prepared by electrolytic fluorination is low, and the discharge of "three wastes" is serious, which has a significant impact on the environment.
[0006] In early synthesis, hydrofluoroethers were prepared by elimination reactions between fluorinated alcohols (or phenols) and haloalkanes, with Rf1X + Rf2OH reacting to give Rf1ORf2 + MX (where Rf is a fluorinated alkyl group and X is I, Br, or Cl). However, this method requires high temperature and pressure and has a low yield of hydrofluoroethers, and it has now been phased out.
[0007] How to achieve the industrial production of methyl trifluoromethyl ether is a technical problem that urgently needs to be solved. Summary of the Invention
[0008] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing methyl trifluoromethyl ether, which is suitable for industrial production.
[0009] To achieve the above objectives, the present invention provides a method for preparing methyl trifluoromethyl ether, comprising the following steps:
[0010] Trifluoromethyl fluoroformate reacts with a methylating agent in the presence of a fluoride salt to give methyltrifluoromethyl ether.
[0011] The fluoride salt is preferably an alkali metal fluoride and / or tetramethylammonium fluoride. In some specific embodiments, the fluoride salt includes one or more of sodium fluoride, potassium fluoride, cesium fluoride, and tetramethylammonium fluoride. Potassium fluoride or cesium fluoride is most preferred.
[0012] The methylating agent is preferably selected from: dimethyl sulfate, iodomethane, bromomethane, chloromethane, methyl p-toluenesulfonate, or methyl fluoroformate.
[0013] The reaction temperature is preferably 0~200℃, more preferably 25~160℃, and even more preferably 30~150℃. For example, it can be 30, 45, 60 or 150℃.
[0014] The reaction time is preferably 1 to 100 hours, more preferably 4 to 48 hours, and even more preferably 18 to 36 hours. For example, it can be 18, 24, or 36 hours.
[0015] The pressure of the reaction is preferably 0 to 100 kg, more preferably 0 to 20 kg, and for example, it can be 0, 10 or 20 kg.
[0016] The solvent for the reaction preferably includes one or more of the following: diethylene glycol dimethyl ether (DG), tetraethylene glycol dimethyl ether, N,N-dimethylformamide (DMF), dimethyl sulfoxide, and acetonitrile.
[0017] In this invention, when the methylating agent is dimethyl sulfate, a solvent may or may not be used.
[0018] To further improve the reaction yield, preferably, a phase transfer catalyst is added to the reaction system.
[0019] Preferably, the phase transfer catalyst comprises one or more of polyether, quaternary ammonium salt, and crown ether.
[0020] The polyether is preferably selected from polyethylene glycol dialkyl ether.
[0021] The quaternary ammonium salt is preferably selected from one or more of benzyltriethylammonium chloride (TEBA), tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride, tetrabutylammonium bisulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, and hexadecyltrimethylammonium chloride.
[0022] The crown ether is preferably selected from one or more of 15-crown-5 and 18-crown-6.
[0023] In some preferred embodiments, the phase transfer catalyst is selected from one or more of tetrabutylammonium bromide, trioctylmethylammonium chloride, and 18-crown-6.
[0024] The molar ratio of trifluoromethyl fluoroformate to fluoride salt is preferably 1:(2~20), more preferably 1:(2~5).
[0025] The molar ratio of trifluoromethyl fluoroformate to the methylating agent is preferably 1:(2~20), more preferably 1:(2~10).
[0026] The molar ratio of trifluoromethyl fluoroformate to the phase transfer catalyst is preferably 1:(0~1), more preferably 1:(0~0.5). In some preferred embodiments, the amount of phase transfer catalyst added is not zero.
[0027] The present invention does not impose any special limitations on the specific process of the preparation method, and can be carried out in accordance with methods well known to those skilled in the art.
[0028] Preferably, the reaction system is dehydrated under vacuum before the reaction.
[0029] In some specific implementation schemes, before feeding the materials, the reaction system is heated to 100~140℃, vacuumed to remove water for 0.5~5 hours, and then nitrogen is introduced and the pressure is maintained until it drops to room temperature.
[0030] The temperature for vacuum dehydration is preferably 110~130℃, and for example, it can be 110, 120 or 130℃. The time for vacuum dehydration is preferably 1~3h, and for example, it can be 1, 2 or 3h.
[0031] In some specific implementations, the preparation method specifically includes the following steps:
[0032] Solvent, fluoride salt, methylating agent and trifluoromethyl fluoroformate are added to the reaction vessel, a phase transfer catalyst is selectively added, the reaction vessel is sealed, and then the reaction is stirred for a certain time under certain temperature and pressure.
[0033] After the reaction is complete, the product is preferably obtained by distillation.
[0034] The present invention does not impose any special limitations on the distillation, and distillation methods well known to those skilled in the art can be used.
[0035] Compared with the prior art, the present invention provides a method for preparing methyl trifluoromethyl ether, comprising the following steps: reacting trifluoromethyl fluoroformate with a methylating agent in the presence of a fluoride salt to obtain methyl trifluoromethyl ether.
[0036] Existing technologies primarily use carbonyl fluoride as a raw material to synthesize methyl trifluoromethyl ether in the presence of alkali metal fluorides and methylating agents. However, the problem lies in the highly toxic nature of carbonyl fluoride, posing safety risks during its preparation and use. Furthermore, the synthesis of hydrofluoroethers from carbonyl fluoride involves high reaction pressures, stringent equipment requirements, and substantial investment. Moreover, carbonyl fluoride is difficult to obtain and expensive, further contributing to the high production cost of HFE-143m.
[0037] This invention uses trifluoromethyl fluoroformate instead of fluorocarbonyl fluoride, avoiding the use of the highly toxic raw material fluorocarbonyl fluoride and reducing equipment requirements. The reaction conditions are relatively mild, the process is simple, and the product is easy to separate. Detailed Implementation
[0038] To further illustrate the present invention, a detailed description is provided below with reference to embodiments. However, it should be understood that these descriptions are merely for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.
[0039] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.
[0040] Example 1
[0041] The reaction was carried out in a 1L Monel reactor system. Before feeding, the reaction system was heated to 120°C and evacuated for 2 hours to remove water. Then, nitrogen gas was introduced and the pressure was maintained until the system cooled to room temperature.
[0042] Under nitrogen protection, 500g of dry dimethyl sulfate and 167.2g of cesium fluoride were added to the reactor. The reactor was sealed, and 66g of trifluoromethyl fluoroformate gas was introduced into the reactor through a stainless steel trifluoromethyl fluoroformate storage tank. The reaction was stopped at 30°C for 24 hours. Subsequently, 85.7g of methyl trifluoromethyl ether was obtained by cryogenic distillation, with a yield of 85.7% and a purity of 99.5%. 19 FNMR (400 MHz) delta-68.4 (s, 3F); 1 H NMR (400 MHz, CDCl3) δ3.9 (s, 3H).
[0043] Example 2
[0044] The reaction was carried out in a 1L Monel reactor system. Before feeding, the reaction system was heated to 120°C and evacuated for 2 hours to remove water. Then, nitrogen gas was introduced and the pressure was maintained until the system cooled to room temperature.
[0045] Under nitrogen protection, 500g of dry dimethyl sulfate and 63.8g of potassium fluoride were added to the reactor. The reactor was sealed, and 66g of trifluoromethyl fluoroformate gas was introduced into the reactor through a stainless steel trifluoromethyl fluoroformate storage tank. The reaction was stopped at 90℃ for 24 hours. Subsequently, 79g of methyl trifluoromethyl ether was obtained by cryogenic distillation, with a yield of 79% and a purity of 99.5%. 19 F NMR (400 MHz) delta-68.4 (s, 3F); 1 H NMR (400 MHz, CDCl3) δ3.9 (s, 3H).
[0046] Example 3
[0047] The reaction was carried out in a 1L Monel reactor system. Before feeding, the reaction system was heated to 120°C and evacuated for 2 hours to remove water. Then, nitrogen gas was introduced and the pressure was maintained until the system cooled to room temperature.
[0048] Under nitrogen protection, 500g of dry dimethyl sulfate, 63.8g of potassium fluoride, and 5g of tetrabutylammonium bromide were added to the reactor. The reactor was sealed, and 66g of trifluoromethyl fluoroformate gas was introduced into the reactor through a stainless steel trifluoromethyl fluoroformate storage tank. The reaction was stopped at 30°C for 24 hours. Subsequently, 94g of methyl trifluoromethyl ether was obtained by cryogenic distillation, with a yield of 94% and a purity of 99%. 19 F NMR (400 MHz) delta-68.4 (s, 3F); 1 H NMR (400 MHz, CDCl3) δ3.9 (s, 3H).
[0049] Example 4
[0050] The reaction was carried out in a 1L Monel reactor system. Before feeding, the reaction system was heated to 120°C and evacuated for 2 hours to remove water. Then, nitrogen gas was introduced and the pressure was maintained until the system cooled to room temperature.
[0051] Under nitrogen protection, 500g of dry DMF, 151.4g of dimethyl sulfate, and 63.8g of potassium fluoride were added to the reactor. The reactor was sealed, and 66g of trifluoromethyl fluoroformate gas was introduced into the reactor through a stainless steel trifluoromethyl fluoroformate storage tank. The reaction was stopped at 30°C for 24 hours. Subsequently, 83g of methyl trifluoromethyl ether was obtained by cryogenic distillation, with a yield of 83% and a purity of 99.5%. 19 F NMR (400 MHz) delta-68.4 (s, 3F); 1 H NMR (400 MHz, CDCl3) δ3.9 (s, 3H).
[0052] Example 5
[0053] The reaction was carried out in a 1L Monel reactor system. Before feeding, the reaction system was heated to 120°C and evacuated for 2 hours to remove water. Then, nitrogen gas was introduced and the pressure was maintained until the system cooled to room temperature.
[0054] Under nitrogen protection, 500g of dry DMF, 63.8g of potassium fluoride, and 170.3g of iodomethane were added to the reactor. The reactor was sealed, and 66g of trifluoromethyl fluoroformate gas was introduced into the reactor through a stainless steel trifluoromethyl fluoroformate storage tank. The reaction was stopped at 40°C for 24 hours. Subsequently, 81g of methyl trifluoromethyl ether was obtained by cryogenic distillation, with a yield of 81% and a purity of 98%. 19 FNMR (400 MHz) delta-68.4 (s, 3F); 1 H NMR (400 MHz, CDCl3) δ3.9 (s, 3H).
[0055] Example 6
[0056] The reaction was carried out in a 1L Monel reactor system. Before feeding, the reaction system was heated to 120°C and evacuated for 2 hours to remove water. Then, nitrogen gas was introduced and the pressure was maintained until the system cooled to room temperature.
[0057] Under nitrogen protection, 500g of dry DG, 151.4g of dimethyl sulfate, and 63.8g of potassium fluoride were added to the reactor. The reactor was sealed, and 66g of trifluoromethyl fluoroformate gas was introduced into the reactor through a stainless steel trifluoromethyl fluoroformate storage tank. The reaction was stopped at 140℃ for 24 hours. Subsequently, 88g of methyl trifluoromethyl ether was obtained by cryogenic distillation, with a yield of 88% and a purity of 99.5%. 19 F NMR (400 MHz) delta-68.4 (s, 3F); 1 H NMR (400 MHz, CDCl3) δ3.9 (s, 3H).
[0058] Example 7
[0059] The reaction was carried out in a 1L Monel reactor system. Before feeding, the reaction system was heated to 120°C and evacuated for 2 hours to remove water. Then, nitrogen gas was introduced and the pressure was maintained until the system cooled to room temperature.
[0060] Under nitrogen protection, 500g of dry DG, 151.4g of dimethyl sulfate, and 103g of tetramethylammonium fluoride were added to the reactor. The reactor was sealed, and 66g of trifluoromethyl fluoroformate gas was introduced into the reactor through a stainless steel trifluoromethyl fluoroformate storage tank. The reaction was stopped at 50°C for 24 hours. Subsequently, 91g of methyl trifluoromethyl ether was obtained by cryogenic distillation, with a yield of 91% and a purity of 99.5%. 19F NMR (400 MHz) delta-68.4 (s, 3F); 1 H NMR (400 MHz, CDCl3) δ3.9 (s, 3H).
[0061] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A method for preparing methyl trifluoromethyl ether, comprising the following steps: Trifluoromethyl fluoroformate reacts with a methylating agent in the presence of a fluoride salt to give methyltrifluoromethyl ether.
2. The method for preparing methyl trifluoromethyl ether according to claim 1, characterized in that, The fluoride salt is an alkali metal fluoride and / or tetramethylammonium fluoride.
3. The method for preparing methyl trifluoromethyl ether according to claim 2, characterized in that, The fluoride salts include one or more of sodium fluoride, potassium fluoride, cesium fluoride, and tetramethylammonium fluoride.
4. The method for preparing methyl trifluoromethyl ether according to claim 1, characterized in that, The methylating agent is selected from: dimethyl sulfate, iodomethane, bromomethane, chloromethane, methyl p-toluenesulfonate, or methyl fluoroformate.
5. The method for preparing methyl trifluoromethyl ether according to claim 1, characterized in that, The reaction temperature is 0~200℃; the reaction time is 1~100h; and the reaction pressure is 0~100kg.
6. The method for preparing methyl trifluoromethyl ether according to claim 1, characterized in that, The solvents for the reaction include one or more of the following: diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile.
7. The method for preparing methyl trifluoromethyl ether according to claim 1, characterized in that, A phase transfer catalyst is added to the reaction system.
8. The method for preparing methyl trifluoromethyl ether according to claim 7, characterized in that, The phase transfer catalyst includes one or more of polyethers, quaternary ammonium salts, and crown ethers.
9. The method for preparing methyl trifluoromethyl ether according to claim 8, characterized in that, The polyether is selected from polyethylene glycol dialkyl ether; The quaternary ammonium salt is selected from one or more of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, and hexadecyltrimethylammonium chloride; The crown ether is selected from one or more of 15-crown-5 and 18-crown-6.
10. The method for preparing methyl trifluoromethyl ether according to any one of claims 1 to 9, characterized in that, The molar ratio of trifluoromethyl fluoroformate to fluoride salt is 1:(2~20). The molar ratio of trifluoromethyl fluoroformate to the methylating agent is 1:(2~20). The molar ratio of trifluoromethyl fluoroformate to phase transfer catalyst is 1:(0~1).