A high-purity hydrofluoroether compound and preparation method thereof

Abstract

The invention discloses a high-purity hydrofluoroether compound and a preparation method thereof. A crude hydrofluoroether compound is obtained by mixing a fluoroolefin or a fluoroene ether with an alcohol or a phenol and then subjecting the mixture to a catalytic reaction. A small amount of byproduct ene ether in the crude hydrofluoroether compound is precipitated by reaction, and then purified by distillation to obtain a high-purity hydrofluoroether compound. The addition reaction of alcohol and fluoroolefin is simple to operate and has mild reaction conditions. The ions, high boiling point solvents, etc. therein can be removed by distillation to obtain a hydrofluoroether containing an unsaturated bond as a byproduct. The distillation temperature can be selected to be higher than the boiling point of the generated hydrofluoroether and lower than the boiling point of the solvent. The hydrofluoroether compound has high efficiency, low overall cost, simple processing, is non-toxic and more environmentally friendly, has high purity, and the content of the unsaturated bond compound is less than 100ppm. The hydrofluoroether compound can be used in the fields of cleaning fluids, heat exchange materials, dielectric materials, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of new material preparation, and specifically relates to a high-purity hydrofluoroether compound and a preparation method thereof. Background Art

[0002] CFCs (chlorofluorocarbons) are a kind of chemically stable substance that was first used in the refrigeration and cleaning industries, but they can cause greenhouse effects and global warming, directly leading to an increase in ultraviolet radiation entering the atmosphere, which is quite harmful to human society. Hydrofluoroethers are ideal substances for modern industry because they do not contain ozone-depleting elements such as chlorine and bromine. They are heteroatom compounds composed of elements such as C, H, F, and O, and have the advantages of being non-toxic, non-flammable, stable, and having very low ODP and GWP values. In recent years, both domestic and foreign countries have been seeking global symbiosis and green industries, so hydrofluoroether compounds have become hot high-end compound materials in the fields of cleaning fluids, heat exchange materials, and dielectric materials.

[0003] Hydrofluoroether compounds have a variety of synthetic routes: 1) fluorination of ethers with fluorine gas or high-valent metal fluoride compounds; 2) electrochemical fluorination of ethers; 3) substitution reaction of alcohols and halogenated hydrocarbons; 4) addition reaction of alcohols and fluorinated olefins, etc. Although F2 has the highest activity in the first fluorination method, it also has the worst selectivity. The fluorination yield of metal fluorides is high but the cost is high, which also limits its use; and although the electrochemical method can synthesize isolated hydrofluoroethers, it consumes a lot of electricity and generally requires a large amount of anhydrous hydrogen fluoride in the process. The product contains a large number of isomers with similar properties, which are almost impossible to effectively separate and are not suitable for industrial applications; the third substitution reaction of alcohols and halogenated hydrocarbons has relatively harsh conditions such as high temperature and high pressure, and has a low yield and a long cycle, and has basically been eliminated.

[0004] For example, patent CN 101263103 A discloses a hydrofluoroether compound and its preparation and use method, which is a method of adding fluoroolefin or olefin ether to alcohol or fluoroalcohol, and can be used in the fields of fire extinguishing agent, foam plastics, vapor phase welding, heat transfer, etc. It also discloses that the reaction product is purified by distillation, and the olefin reaction by-product is removed by a reagent that preferentially reacts with the double bond of the olefin, such as anhydrous hydrogen fluoride, aprotic solvent potassium difluoride, potassium permanganate in acetone, bromine, etc. This method can remove a considerable part of the unsaturated impurity compounds, but the selected reagents are relatively dangerous and are also prone to produce more by-products, making purification and waste treatment more difficult.

[0005] Patent CN 114456046 A discloses a high-purity hydrofluoroether and a purification method thereof, wherein a catalyst and an oxidant are added to a crude product containing unsaturated bond impurities, an oxidation reaction is carried out, and then the high-purity hydrofluoroether is obtained by distillation. Although this method has mild reaction conditions, convenient operation, and is environmentally friendly, it still requires distillation to obtain the product, and the removal efficiency still needs to be improved. In addition, a variety of catalysts and catalyzers are used, and the output is carried out in a layered manner. The removal of the intermediate complex layer causes a significant reduction in the yield, and the subsequent water removal cost after washing is high, the production cycle is long, and the subsequent environmental protection treatment problem of the upper liquid is increased. Similarly, patent CN 114456045A also has similar problems, and uses relatively expensive catalysts such as hydrogen peroxide, periodate, and heavy metals.

[0006] Patent CN 112341319 A discloses a method for comprehensive utilization of fluorinated ether byproducts in the production process of hydrofluoroethers, which uses a treatment method of adding sulfuric acid. However, sulfuric acid is highly corrosive to equipment, and this method has been gradually eliminated in the prior art.

[0007] Hydrofluoroether products contain unsaturated compounds such as olefinic ether compounds, which have a boiling point close to that of the target product hydrofluoroether and are difficult to separate using conventional process methods. The residual unsaturated compounds will cause the product to react with equipment materials during application scenarios. For example, when used as a high-end electronic heat transfer material, it will react and corrode the equipment, causing irreparable damage and affecting the storage period. Another example is that using it as a reaction solvent may lead to reaction failure, etc.

[0008] Therefore, the methods for preparing high-purity hydrofluoroethers in the prior art have the problems of low efficiency, environmental pollution, toxicity or corrosiveness, reduced yield, limited ability to improve purity and treatment of residual three wastes, and are not suitable for the trend of green and environmental protection development of modern industry. Summary of the invention

[0009] In order to solve the above problems existing in the prior art, the present invention aims to provide a high-purity hydrofluoroether compound and a preparation method thereof, which has low content of unsaturated compounds, high efficiency, high purity, less residual three wastes, meets environmental protection requirements, and can save cost investment.

[0010] The technical solution adopted by the present invention is:

[0011] A high-purity hydrofluoroether compound is obtained by subjecting a hydrofluoroether crude mixture to the steps of distillation, addition precipitation, filtration and rectification.

[0012] Furthermore, the crude hydrofluoroether is prepared by mixing fluoroolefin or fluoroolefin ether with alcohol or phenol, adding alkaline substances and solvents, and subjecting the mixture to a catalytic etherification reaction.

[0013] Furthermore, the GC% content of unsaturated by-products in the crude hydrofluoroether is ≤25%.

[0014] Furthermore, the fluoroolefin is tetrafluoroethylene or hexafluoropropylene.

[0015] Furthermore, the fluoroolefin ether is CmF2m+1-O-CF=CF2, wherein m is an integer from 1 to 6.

[0016] Furthermore, the alcohol is methanol, ethanol, isopropanol, 1-butanol, 2-butanol, 1,2-propylene glycol, 1,3-propylene glycol or a fluoroalcohol.

[0017] Furthermore, the phenol is phenol or fluorophenol.

[0018] The present invention also relates to a method for preparing a high-purity hydrofluoroether compound, which is used to prepare the above-mentioned high-purity hydrofluoroether compound, and is characterized in that it comprises the following steps:

[0019] S01, distillation: subjecting the synthesized crude hydrofluoroether mixture to simple distillation to obtain a crude hydrofluoroether;

[0020] S02, addition precipitation: dehydrate and deoxygenate the high-pressure sealed stainless steel reactor to an oxygen content of less than 20 ppm; add 0.05 to 2 parts of a multifunctional branched initiator and 40 to 80 parts of a crude hydrofluoroether in the high-pressure sealed stainless steel reactor by weight; start stirring and heat to 40 to 95° C., react for 2 to 8 hours, then cool and discharge to obtain a reaction mass;

[0021] S03, filtration: the reaction material is filtered under pressure through a 150-350 nm filter screen, and the filtered liquid is transported to a distillation tower;

[0022] S04, distillation: The filtered liquid mixture is subjected to two-stage distillation absorption to obtain a distilled liquid.

[0023] Furthermore, the multifunctional branched initiator in step S028 is a peroxide-type multifunctional branched initiator derived from β-cyclodextrin, and its structural formula can be expressed as:

[0024]

[0025] Wherein β-CD represents a β-cyclodextrin group, and n is an integer of 1 to 7.

[0026] Finally, the pressure of the pressure filtration in step S03 is 0.1-2.0 MPa.

[0027] The beneficial effects of the present invention are:

[0028] A high-purity hydrofluoroether compound and a preparation method thereof, wherein a fluoroolefin or a fluoroene ether is mixed with an alcohol or a phenol and subjected to a catalytic reaction to obtain a crude hydrofluoroether compound, a small amount of by-product ene ether in the crude hydrofluoroether compound is reacted and precipitated, and then a conventional distillation and purification operation is performed to obtain a high-purity hydrofluoroether compound. The addition reaction of alcohol and fluoroolefin is simple to operate and has mild reaction conditions. Ions, high-boiling-point solvents and the like can be removed by distillation to obtain hydrofluoroether containing unsaturated bonds as byproducts. The distillation temperature can be selected to be higher than the boiling point of the generated hydrofluoroether and lower than the boiling point of the solvent. The obtained hydrofluoroether compound has high purity, with a hydrofluoroether purity of ≥99.85%, and in particular, the content of unsaturated bond compounds is lower than 100ppm. The method has the advantages of high efficiency, low overall cost, simple and easy-to-control process steps, no toxicity and more environmental protection, and will not cause harm to equipment and human body, meeting the requirements of modern high-quality green industrial system. The method has less residual three wastes, meets environmental protection requirements, and can save cost investment. The method can be used in the fields of cleaning of precision instruments and equipment and as a heat transfer medium, and can also be extended to the fields of cleaning fluids, heat exchange materials, dielectric materials, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the process of reacting β-cyclodextrin with 1,3,5-triacyl chloride benzene through a multifunctional branched initiator and then reacting with tert-butyl hydroperoxide in the preparation method of the high-purity hydrofluoroether compound in Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in 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, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In order to provide a high-purity hydrofluoroether compound and a preparation method thereof, the overall planning scheme of the present invention is as follows: firstly, a high-purity hydrofluoroether compound is conceived, which is obtained by subjecting a crude hydrofluoroether mixture to distillation, addition precipitation, filtration and rectification steps.

[0032] Furthermore, the crude hydrofluoroether is prepared by mixing fluoroolefin or fluoroene ether with alcohol or phenol, adding alkaline substance and solvent, and subjecting the mixture to catalytic etherification reaction.

[0033] Furthermore, the GC% content of unsaturated by-products in the crude hydrofluoroether is ≤25%.

[0034] Furthermore, the fluoroolefin is tetrafluoroethylene or hexafluoropropylene.

[0035] Furthermore, the fluoroolefin ether is CmF2m+1-O-CF=CF2, wherein m is an integer from 1 to 6.

[0036] Furthermore, the alcohol is methanol, ethanol, isopropanol, 1-butanol, 2-butanol, 1,2-propylene glycol, 1,3-propylene glycol or a fluoroalcohol.

[0037] Furthermore, the phenol is phenol or fluorophenol.

[0038] The technical solution of the present invention focuses on the chemical impurity removal and purification of hydrofluoroethers. The preparation process of hydrofluoroether products is: first catalytic synthesis, and then post-treatment, that is, the preparation process of high-purity hydrofluoroethers in the present invention. The synthesis is generally a catalytic etherification reaction of fluoroolefins, ethers and alcohols, phenols in the presence of alkaline substances and solvents. Side reactions or rearrangement reactions will occur in the process. The by-products are complex, generally liquid impurities of olefin ethers containing double bonds, which have serious adverse effects on the stability during use, especially in the application fields of cleaning, heat exchange media, etc., which are the key applications of the present invention. The boiling point is close to that of the target product (no double bonds) hydrofluoroether, and it is difficult to remove them completely by distillation;

[0039] The by-products are unsaturated by-products containing unsaturated bonds, that is, various structural by-products of double bonds. Such products are only different from the target products in double bonds, and have similar boiling points. They are not easy to remove by general purification methods, and the structural types cannot be determined. They can only be detected by GC content; the content of unsaturated compounds is ≤25%, that is, the content of hydrofluoroether is ≥75%. Whether it is a crude product or a purified product, as well as the impurities therein, they are all liquids. Because of this, ordinary physical separation such as distillation cannot remove them completely under the premise of close boiling points.

[0040] The present invention focuses on using a new type of initiator with initiation function to polymerize and adsorb it, which is incompatible with the liquid phase and precipitates to achieve the purpose of impurity removal. The key technical solution of the present invention is to use a new type of initiator compound with synergistic function, which is not recorded in the existing literature; and then distill to remove the trace amount of solvents and other substances remaining in the synthesis step to obtain a hydrofluoroether compound with ultra-high purity.

[0041] The present invention also relates to a method for preparing a high-purity hydrofluoroether compound, which is used to prepare the above-mentioned high-purity hydrofluoroether compound, and is specifically prepared and performed according to the following steps:

[0042] S01, distillation: subjecting the synthesized crude hydrofluoroether mixture to simple distillation to obtain a crude hydrofluoroether;

[0043] S02, addition precipitation: dehydrate and deoxygenate the high-pressure sealed stainless steel reactor to an oxygen content of less than 20 ppm; add 0.05 to 2 parts of a multifunctional branched initiator and 40 to 80 parts of a crude hydrofluoroether in the high-pressure sealed stainless steel reactor by weight; start stirring and heat to 40 to 95° C., react for 2 to 8 hours, then cool and discharge to obtain a reaction mass;

[0044] Generally, glass kettles or enamel kettles cannot bear pressure, so the present invention uses a high-pressure sealed stainless steel reactor;

[0045] The multifunctional branched initiator is a peroxide-type multifunctional branched initiator derived from β-cyclodextrin, and its structural formula can be expressed as follows:

[0046]

[0047] wherein β-CD represents a β-cyclodextrin group, and n is an integer from 1 to 7;

[0048] S03, filtration: the reaction material is filtered under pressure through a 150-350 nm filter screen, and the filtered liquid is transported to a distillation tower;

[0049] During the pressure filtration process of the present invention, it is only necessary to maintain positive pressure or to achieve the effect of conventional filtration, that is, the pressure parameter is preferably in the range of 0.1-2.0 MPa;

[0050] S04, distillation: The filtered liquid mixture is subjected to two-stage distillation absorption to obtain a distilled liquid.

[0051] Finally, in step S02

[0052] The high-purity hydrofluoroether compound and the preparation method thereof of the present invention are obtained by mixing fluoroolefin or fluoroene ether with alcohol or phenol and then catalytically reacting to obtain a crude hydrofluoroether compound, and then a small amount of byproduct ene ether in the crude hydrofluoroether compound is precipitated by reaction, and then the high-purity hydrofluoroether compound is obtained by conventional distillation and purification. The addition reaction of alcohol and fluoroolefin is simple to operate and the reaction conditions are mild; the ions, high boiling point solvents, etc. therein can be removed by distillation to obtain a hydrofluoroether containing a byproduct of an unsaturated bond, and the distillation temperature can be selected to be higher than the boiling point of the generated hydrofluoroether and lower than the boiling point of the solvent; it has high efficiency, low comprehensive cost, simple processing, non-toxic and more environmentally friendly, the purity of the obtained hydrofluoroether compound is high, especially the content of the unsaturated bond compound is less than 100ppm, which can be used in the fields of cleaning of precision instruments and equipment and as a heat transfer medium, and can also be extended to the fields of cleaning fluids, heat exchange materials, dielectric materials, etc.

[0053] It has the advantages of high efficiency, low comprehensive cost, simple treatment process, non-toxicity and environmental protection, etc., with less residual waste, meets environmental protection requirements, and can save cost investment; it can be used for cleaning precision instruments and equipment and as a heat transfer medium, and can also be promoted to the fields of cleaning fluids, heat exchange materials, dielectric materials, etc.

[0054] The specific operations are as follows:

[0055] A method for obtaining a high-purity hydrofluoroether compound, wherein a crude hydrofluoroether mixture is obtained through distillation, addition precipitation, filtration, and rectification steps;

[0056] The crude hydrofluoroether is obtained by catalytic reaction of fluoroolefin or fluoroolefin ether with alcohol or phenol, wherein the GC% content of unsaturated by-products is ≤25%;

[0057] Fluoroolefin ether is CmF2m+1-O-CF=CF2, where m is an integer from 1 to 6;

[0058] The alcohol is one of methanol, ethanol, isopropanol, 1-butanol, 2-butanol, 1,2-propylene glycol, 1,3-propylene glycol, and a fluoroalcohol; the phenol is one of phenol and a fluorophenol;

[0059] The specific steps are as follows: by weight,

[0060] 1) Distillation: The synthesized mixture is subjected to simple distillation to obtain a crude hydrofluoroether product and then sent to a high-pressure reactor;

[0061] 2) Addition precipitation: remove water and oxygen from a high-pressure sealed stainless steel reactor to an oxygen content of less than 20 ppm, add 0.05 to 2 parts of a novel multifunctional branched initiator and 40 to 80 parts of the crude hydrofluoroether described in 1), start stirring and heat to 40 to 95° C., react for 2 to 8 hours, then cool and discharge;

[0062] 3) Filtration: The material from step 2) is filtered under pressure through a 150-350 nm filter screen, and the filtered liquid is sent to the distillation tower;

[0063] 4) Distillation: The liquid mixture in step 3) is subjected to two-stage distillation and absorption to obtain the high-purity hydrofluoroether composition;

[0064] The functional multi-branched initiator is a peroxide multi-functional branched initiator derived from β-cyclodextrin, and its structural formula can be expressed as:

[0065]

[0066] wherein β-CD represents a β-cyclodextrin group, and n is an integer from 1 to 7;

[0067] The method for obtaining high-purity hydrofluoroether compounds of the present invention is to etherify fluoroolefins or fluoroene ethers with alcohols or phenols to obtain a crude hydrofluoroether mixture, and then polymerize and precipitate the crude hydrofluoroether obtained after simple distillation to remove unsaturated compounds therein, and then remove solids by filtering, and then obtain high-purity hydrofluoroether compounds by two-stage distillation. The fluoroolefin is one of tetrafluoroethylene and hexafluoropropylene, the fluoroene ether is CmF2m+1-O-CF=CF2, wherein m is an integer of 1 to 6; the alcohol is one of methanol, ethanol, isopropanol, 1-butanol, 2-butanol, 1,2-propylene glycol, 1,3-propylene glycol, and fluoroalcohol; the phenol is one of phenol and fluorophenol. The reaction product generally contains metal ions, solvents, crude hydrofluoroether and other components. The catalytic addition reaction has high selectivity and can control the GC% content of unsaturated by-products to be ≤25% during the synthesis stage. The ions, high-boiling point solvents and the like can be removed by distillation to obtain hydrofluoroether containing unsaturated bonds as by-products. The distillation temperature can be selected to be higher than the boiling point of the generated hydrofluoroether and lower than the boiling point of the solvent.

[0068] The crude hydrofluoroether of the present invention is subjected to a polymerization precipitation process to remove unsaturated compounds. The removal process is that unsaturated compounds such as olefin ethers undergo addition polymerization under a novel multifunctional branched initiator to form free radical addition polymerization, and then the obtained polymer containing the terminal initiator is precipitated to achieve separation from the hydrofluoroether product. The process is: dewater and deoxygenate the high-pressure closed stainless steel reactor to an oxygen content of less than 20ppm, add 0.05 to 2 parts of the novel multifunctional branched initiator, 40 to 80 parts of the distilled crude hydrofluoroether, start stirring and heat to 40 to 95°C, react for 2 to 8 hours, cool down and discharge. The novel functional multi-branched initiator described in the present invention is a peroxide multifunctional branched initiator derived from β-cyclodextrin, and its structural formula can be expressed as:

[0069]

[0070] Wherein β-CD represents a β-cyclodextrin group, and n is an integer of 1 to 7. It is a multi-branched organic initiator compound derived from β-cyclodextrin. β-Cyclodextrin is a cone-shaped substance that is narrow at the top and wide at the bottom. The wide lower part has a large steric hindrance, and there are fewer active hydroxyl groups that react. The hydroxyl groups in the narrow upper part are more active due to the small steric hindrance, and partial and full derivatization reactions can be achieved. By utilizing this difference in activity, an umbrella-shaped multi-branched product can be formed. The novel multifunctional branched initiator of the present invention is produced by reacting β-cyclodextrin with 1,,3,5-triacyl chloride benzene, and then reacting with tert-butyl hydroperoxide. The reaction process is as follows: Figure 1 shown.

[0071] The novel multifunctional branched initiator of the present invention has good fluidity, and has a large specific surface area by virtue of the cavity of beta-cyclodextrin, so that the reactive unsaturated bonds can be captured more effectively. In addition, the reaction uses a hydrofluoroether containing an unsaturated compound as a solvent, and the liquid phase reaction also improves the polymerization efficiency and heat transfer stability, making the reaction easier to control and more stable. The fluorine-containing part of the terminal initiator polymer produced by the polymerization dissolves and swells to expose more initiator endpoints. After the polymer chain is enlarged, it becomes insoluble in the hydrofluoroether and precipitates to terminate the reaction. The multi-branched initiator endpoints play a very important role in capturing trace amounts of unsaturated bonds.

[0072] The polymer precipitated by the present invention is a granular substance with a shell-core structure, which can be completely removed by pressure filtration through a 150-350nm filter without causing clogging of the filter, and the filter can be reused after simple cleaning and purging. To ensure purity, the filtered product is subjected to two-stage distillation to obtain the high-purity hydrofluoroether compound of the present invention.

[0073] The present invention also discloses a high-purity hydrofluoroether compound. The high-purity hydrofluoroether compound prepared by the above method has an unsaturated compound content of less than 100 ppm and can be used for cleaning fine instruments and equipment and as a heat transfer medium.

[0074] The following six raw material combinations in Table 1 were reacted and etherified to prepare a crude hydrofluoroether mixture, and the high-purity hydrofluoroether compound and the preparation method thereof of the present invention were verified by comparing Examples 1 to 9 with Comparative Examples 1 to 2.

[0075] Table 1:

[0076]

[0077]

[0078] Embodiment 1:

[0079] According to the above-mentioned operating steps S01 to S04, the FE-1 hydrofluoroether crude mixture is used, and the addition amount is 40 parts; the addition amount of the new multifunctional branched initiator is 0.02 parts, and its n=4; the addition precipitation temperature is 80°C, the addition precipitation time is 4 hours, and the filter fineness is 350nm.

[0080] The preparation process was normal and could be easily controlled. The purity of the high-purity hydrofluoroether composition finally obtained was 99.90%, and the content of unsaturated compounds was 80 ppm.

[0081] Embodiment 2:

[0082] According to the above-mentioned operating steps S01 to S04, the FE-2 hydrofluoroether crude mixture is used, and the addition amount is 60 parts; the addition amount of the new multifunctional branched initiator is 1 part, and its n=6; the addition precipitation temperature is 70°C, the addition precipitation time is 4 hours, and the filter fineness is 220nm.

[0083] The preparation process was normal and could be easily controlled. The purity of the high-purity hydrofluoroether composition finally obtained was 99.95% and the content of unsaturated compounds was 50 ppm.

[0084] Example 3: According to the above-mentioned operating steps S01 to S04, a crude mixture of FE-3 hydrofluoroether is used, and the addition amount is 60 parts; the addition amount of the new multifunctional branched initiator is 2 parts, where n=1; the addition precipitation temperature is 70°C, the addition precipitation time is 2 hours, and the filter fineness is 220nm.

[0085] The preparation process was normal and could be easily controlled. The purity of the high-purity hydrofluoroether composition finally obtained was 99.85%, and the content of unsaturated compounds was 100 ppm.

[0086] Example 4: According to the above-mentioned operating steps S01 to S04, the FE-2 hydrofluoroether crude mixture is used, and the addition amount is 80 parts; the addition amount of the new multifunctional branched initiator is 0.8 parts, where n=3; the addition precipitation temperature is 60°C, the addition precipitation time is 6 hours, and the filter fineness is 100nm.

[0087] The preparation process was normal and could be easily controlled. The purity of the high-purity hydrofluoroether composition finally obtained was 99.88%, and the content of unsaturated compounds was 80 ppm.

[0088] Example 5: According to the above-mentioned operating steps S01 to S04, a crude mixture of FE-3 hydrofluoroether is used, and the addition amount is 50 parts; the addition amount of the new multifunctional branched initiator is 1.5 parts, and its n=7; the addition precipitation temperature is 95°C, the addition precipitation time is 8 hours, and the filter fineness is 300nm.

[0089] The preparation process was normal and could be easily controlled. The purity of the high-purity hydrofluoroether composition finally obtained was 99.89% and the content of unsaturated compounds was 90 ppm.

[0090] Example 6: According to the above-mentioned operating steps S01 to S04, a crude mixture of FE-4 hydrofluoroether is used, and the addition amount is 60 parts; the addition amount of the new multifunctional branched initiator is 0.5 parts, and its n=6; the addition precipitation temperature is 80°C, the addition precipitation time is 6 hours, and the filter fineness is 300nm.

[0091] The preparation process was normal and could be easily controlled. The purity of the high-purity hydrofluoroether composition finally obtained was 99.88%, and the content of unsaturated compounds was 95 ppm.

[0092] Example 7: According to the above-mentioned operating steps S01 to S04, the FE-5 hydrofluoroether crude mixture is used, and the addition amount is 80 parts; the addition amount of the new multifunctional branched initiator is 1.5 parts, where n=5; the addition precipitation temperature is 40°C, the addition precipitation time is 4 hours, and the filter fineness is 220nm.

[0093] The preparation process was normal and could be easily controlled. The purity of the high-purity hydrofluoroether composition finally obtained was 99.98% and the content of unsaturated compounds was 50 ppm.

[0094] Example 8: According to the above-mentioned operating steps S01 to S04, the FE-4 hydrofluoroether crude mixture is used, and the addition amount is 60 parts; the addition amount of the new multifunctional branched initiator is 0.3 parts, and its n=6; the addition precipitation temperature is 80°C, the addition precipitation time is 6 hours, and the filter fineness is 150nm.

[0095] The preparation process was normal and could be easily controlled. The purity of the high-purity hydrofluoroether composition finally obtained was 99.95% and the content of unsaturated compounds was 80 ppm.

[0096] Example 9: According to the above-mentioned operating steps S01 to S04, a crude mixture of FE-6 hydrofluoroether is used, and the addition amount is 40 parts; the addition amount of the new multifunctional branched initiator is 0.1 parts, and its n=4; the addition precipitation temperature is 60°C, the addition precipitation time is 4 hours, and the filter fineness is 150nm.

[0097] The preparation process was normal and could be easily controlled. The purity of the high-purity hydrofluoroether composition finally obtained was 99.93% and the content of unsaturated compounds was 90 ppm.

[0098] Comparative Example 1: According to the above-mentioned steps of S01 to S04, but without the addition precipitation step, the same FE-2 hydrofluoroether crude mixture as in Example 2 was used. Although the content of unsaturated compounds in the high-purity hydrofluoroether composition finally obtained was 20%, it was difficult to filter in the later stage of the preparation process and it was also difficult to clean the filter.

[0099] Comparative Example 2: According to the operating steps of S01 to S04 above, a crude FE-2 hydrofluoroether mixture was used, and tert-butyl triperoxide of tribenzoate was used as an addition precipitation initiator, but it was not combined with the β-cyclodextrin described in the present invention. The amount of tert-butyl triperoxide of tribenzoate was 6 parts, where n=6; the addition precipitation temperature was 70°C, the addition precipitation time was 4 hours, and the filter fineness was 220nm.

[0100] Although the content of unsaturated compounds in the finally prepared high-purity hydrofluoroether composition is 0.5%, tiny particles still appear after distillation during its preparation process.

[0101] Comparative Example 1 is a chemical purification method without the addition precipitation of the present invention, and only simple distillation, filtration, rectification and the like in the present invention are used to highlight the advantages and necessity of addition precipitation.

[0102] In Comparative Example 2, a chemical method is used for purification and impurity removal, but only a part of the branched initiator of the present invention (tert-butyl triperoxide of tribenzoate, which is the group part that plays an initiating role) is used without the β-cyclodextrin combination, thereby highlighting the advantages and synergistic effects of the combination of the two parts of the new initiator; the comparison results are: the two comparative examples have considerable differences in purity and the content of unsaturated impurities compared with the embodiments of the present invention, thereby highlighting the advantages of the chemical method for impurity removal and purification of the present invention.

[0103] The comparative verification results of Examples 1 to 9 and Comparative Examples 1 to 2 are shown in Table 2:

[0104] Table 2:

[0105]

[0106]

[0107] Compared with the prior art, the high-purity hydrofluoroether compound and the preparation method thereof of the present invention have the following technical features:

[0108] 1. The product has high purity, the purity of hydrofluoroether is ≥99.85%, and the content of unsaturated compounds is less than 100ppm;

[0109] 2. High efficiency, low comprehensive cost, simple and easy-to-control process steps, no harm to equipment and human body, etc., in line with the requirements of modern high-quality green industrial system;

[0110] 3. The application range is wide, and the product can be used for cleaning of higher-end precision instruments and equipment and as a heat transfer medium.

[0111] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-purity hydrofluoroether compound, for preparing a high-purity hydrofluoroether compound, characterized in that: The following steps are included: S01, distillation: subjecting the synthesized crude hydrofluoroether mixture to simple distillation to obtain a crude hydrofluoroether; S02, addition precipitation: dehydrate and deoxygenate the high-pressure sealed stainless steel reactor to an oxygen content of less than 20 ppm; add 0.05 to 2 parts of a multifunctional branched initiator and 40 to 80 parts of a crude hydrofluoroether in the high-pressure sealed stainless steel reactor by weight; start stirring and heat to 40 to 95° C., react for 2 to 8 hours, then cool and discharge to obtain a reaction mass; S03, filtration: the reaction material is filtered under pressure through a 150-350 nm filter screen, and the filtered liquid is transported to a distillation tower; S04, distillation: subjecting the filtered liquid mixture to two-stage distillation absorption to obtain a distilled liquid; The multifunctional branched initiator in step S02 is a peroxide-type multifunctional branched initiator derived from β-cyclodextrin, and its structural formula is: wherein β-CD represents a β-cyclodextrin group, and n is an integer from 1 to 7; The crude hydrofluoroether is prepared by mixing fluoroolefin or fluoroolefin ether with alcohol or phenol, adding alkaline substances and solvents, and subjecting the mixture to catalytic etherification reaction; The GC% content of unsaturated by-products in the crude hydrofluoroether is ≤25%.

2. The method for preparing a high-purity hydrofluoroether compound according to claim 1, characterized in that: The fluoroolefin is tetrafluoroethylene or hexafluoropropylene.

3. The method for preparing a high-purity hydrofluoroether compound according to claim 1, characterized in that: The fluoroolefin ether is CmF2m+1-O-CF=CF2, wherein m is an integer of 1 to 6.

4. The method for preparing a high-purity hydrofluoroether compound according to claim 1, characterized in that: The alcohol is methanol, ethanol, isopropanol, 1-butanol, 2-butanol, 1,2-propylene glycol, 1,3-propylene glycol or a fluoroalcohol.

5. The method for preparing a high-purity hydrofluoroether compound according to claim 1, characterized in that: The phenol is phenol or fluorophenol.

6. The method for preparing a high-purity hydrofluoroether compound according to claim 1, characterized in that: The pressure of the pressure filtration in step S03 is 0.1-2.0 MPa.

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