Purification method for obtaining high-purity hydrofluoroether

Abstract

According to the purification method for obtaining the high-purity hydrofluoroether, the hydrofluoride salt with the acidity weaker than that of hydrofluoric acid is adopted for removing unsaturated impurities from the crude hydrofluoroether product, corresponding hydrofluoroether instead of other impurities is generated, the yield of the hydrofluoroether is increased, and the purity of the hydrofluoroether obtained after treatment is 99.3% or above and can reach 99.9% to the maximum. The method is low in cost, mild in reaction condition, short in reaction time, simple to operate, green, environment-friendly, safe, reliable and low in equipment requirement, and does not need low-temperature, water-free, oxygen-free and other conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrofluoroether preparation and relates to a purification method for obtaining high-purity hydrofluoroether. Background Art

[0002] Hydrofluoroether products are environmentally friendly compounds because they do not damage the ozone layer and have low greenhouse effect potential. They can be used as a new generation of chlorofluorocarbon substitutes and have the potential to be used as cleaning agents, solvents, foaming agents, heat exchange media, etc.

[0003] In the prior art, hydrofluoroethers are usually prepared by nucleophilic addition of alkyl alcohols and fluorinated olefins. In the preparation process of hydrofluoroethers, it is inevitable to produce dehydrofluorination byproducts with unsaturated bonds, that is, the crude hydrofluoroether contains unsaturated impurities. Since the boiling point of unsaturated impurities is usually very close to that of the target product hydrofluoroether, it is difficult to remove the unsaturated impurities in the crude hydrofluoroether by direct distillation.

[0004] At present, the purification methods for obtaining high-purity hydrofluoroether mainly include the following: (1) Izvestiya AkademiiNauk SSSR, Seriya Khimicheskaya, 1953, 282-9 discloses the use of bromine to add unsaturated impurities to remove unsaturated impurities in crude 1,1,2,3,3,3-hexafluoropropyl hydrofluoroether. However, this method not only has high bromine cost, but also has high corrosiveness, high corrosion resistance requirements for equipment, and dangerous reactions. (2) Korean patent KR2010138245 discloses a method for removing unsaturated impurities in crude hydrofluoroether using n-hexylamine, but n-hexylamine has high cost. Summary of the invention

[0005] The purpose of the present invention is to provide a purification method for obtaining high-purity hydrofluoroether, so as to solve the problems of high cost and high risk of existing removal methods.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present application provides a purification method for obtaining high-purity hydrofluoroether, the method comprising: S01: Mix the crude hydrofluoroether containing unsaturated impurities with hydrofluoric acid salt at 30-150° C. for reaction for 2-10 hours. After the reaction is completed, cool to room temperature to obtain a reaction solution.

[0007] The crude hydrofluoroether containing unsaturated impurities is mixed with hydrofluoric acid salt at 30-150°C for 2-10h, wherein the molar ratio of unsaturated impurities to hydrofluoric acid salt in the crude hydrofluoroether is 1:0.1-10. After the reaction is completed, it is cooled to room temperature to obtain a reaction solution. In the reaction process of the crude hydrofluoroether and the hydrofluoric acid salt, the unsaturated impurities are olefinic ethers, and the double bonds in the olefinic ethers will react with the complexed hydrogen fluoride in the hydrofluoric acid salt to generate the corresponding hydrogen fluoride adducts, i.e., the corresponding hydrofluoroethers, thereby increasing the yield of the hydrofluoroethers. The boiling points of other impurities in the crude hydrofluoroethers are quite different from those of the hydrofluoroethers, and the removal of other impurities can be achieved by distillation, and the hydrofluoroethers with higher purity can be extracted at the same time.

[0008] In the present application, the hydrofluoroether is prepared by reacting an alcohol or a phenol with a fluorinated olefin, wherein the alcohol or the phenol may be a halogen-containing or halogen-free alcohol or phenol having 1 to 10 carbon atoms, and the fluorinated olefin is an olefin having 1 to 9 carbon atoms and containing or not containing oxygen, sulfur, nitrogen, chlorine or bromine atoms.

[0009] Specifically, the alcohol or phenol in the present application includes but is not limited to methanol, ethanol, propanol, trifluoroethanol, tetrafluoropropanol, hexafluorobutanol, 4-chlorobutanol, octafluoropentanol, cyclohexanol, perfluorobutylethanol, perfluorohexylethanol, perfluorooctylethanol, phenol, fluorophenol, benzyl alcohol, etc. Fluorine-containing olefins include but are not limited to tetrafluoroethylene, trifluoroethylene, vinylidene fluoride, trifluorochloroethylene, trifluorobromoethylene, perfluoropropoxyethylene, perfluoroethoxyethylene, etc.

[0010] Preferably, the alcohol in the present application is trifluoroethanol or 2,2,3,3,4,4,5,5-octafluoropentanol, the phenol is phenol, and the fluorinated olefin is at least one of tetrafluoroethylene and hexafluoropropylene.

[0011] The hydrofluoroether may be, but is not limited to, CH 3 CH 2 OCF 2 CF 2 H (HFE-374), CF 3 CH 2 OCF 2 CF 2 H (HFE-347), HCF 2 CF 2 CH 2 OCF 2 CF 2 H (HFE-458), HCF 2 CF 2 CF 2 CF 2 CH 2 OCF 2 CF 2 H (HFE-6512) or CF3 CH 2 OCF 2 CFHCF 3 (HFE-449). Among them, the GC% content of unsaturated impurities in the crude hydrofluoroether is 0.1-20%.

[0012] Preferably, the unsaturated impurity in the present application is CH 3 CH 2 OCF=CF 2 CF 3 CH 2 OCF=CF 2 CF 2 =CHOCF 2 CF 2 H. HCF 2 CF 2 CF 2 CF 2 CH 2 OCF=CF 2 CF 2 =CFCF 2 CF 2 CH 2 OCF 2 CF 2 H. HCF 2 CF 2 CF 2 CF=CHOCF 2 CF 2 H.CF 2 =CFCH 2 OCF 2 CF 2 H. HCF 2 CF=CHOCF 2 CF 2 H. HCF 2 CF 2 CH 2 OCF=CF 2 CF = CHOCF 2 CFHCF 3 CF 3 CH 2 OCF=CFCF 3 or CF 3 CH 2 OCF 2 CF=CF 2 .

[0013] In the present application, the hydrofluoric acid salt is selected from at least one of sodium bifluoride, potassium bifluoride, and a complex of amine and hydrogen fluoride, wherein the complex of amine and hydrogen fluoride includes triethylamine trihydrogen fluoride, diisopropylethylamine trihydrogen fluoride, N,N-dimethylformamide hydrogen fluoride, hydrogen fluoride amine, pyridine hydrogen fluoride salt, and the like.

[0014] S02: Add water to the reaction solution, stir, and then stand to separate into layers to obtain an upper aqueous phase and a lower organic phase.

[0015] Add water to the reaction solution, wherein the volume ratio of the reaction solution to water is 1:0.5-2. Stir for 10-120 min at a stirring speed of 50-500 rpm, and then stand for stratification to obtain an upper aqueous phase and a lower organic phase.

[0016] S03: The lower organic phase is distilled to obtain a distillation residue and a hydrofluoroether.

[0017] The lower organic phase is added to an intermittent distillation tower, and distilled under normal pressure and a reflux ratio of 10-1:1 to obtain a distillation residue and a hydrofluoroether, wherein the tower bottom temperature is 2-10°C higher than the boiling point of the hydrofluoroether, and the tower top temperature is ±3°C of the boiling point of the hydrofluoroether.

[0018] The present invention has the following beneficial effects: (1) In the present application, a hydrofluoric acid salt with a weaker acidity than hydrofluoric acid is used to remove unsaturated impurities from a crude hydrofluoroether, thereby generating the corresponding hydrofluoroether instead of other impurities, thereby improving the yield of the hydrofluoroether.

[0019] (2) This method has low cost, mild reaction conditions, short reaction time, simple operation, green and environmentally friendly, safe and reliable, low equipment requirements, and does not require low temperature, anhydrous, oxygen-free and other conditions.

[0020] (3) This method has high processing efficiency and good product quality. The purity of the hydrofluoroether obtained after treatment is above 99.3%, and can reach up to 99.9%. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0022] Example 1 The present application provides a purification method for obtaining high-purity hydrofluoroether, the method comprising: S101: 400 g of crude HFE-6512 containing 18 wt% of unsaturated impurities and 34 g of pyridine hydrogen fluoride salt were added to a 500 ml four-necked flask equipped with a reflux tube, so that the molar ratio of unsaturated impurities in the crude HFE-6512 to pyridine hydrogen fluoride salt was 1:1.5. The temperature was raised to 85°C at a stirring speed of 300 rpm, and mixed and reacted at 85°C for 5 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain a reaction solution.

[0023] S102: Add water twice the volume of the reaction solution into a four-necked flask, stir for 30 min at a stirring speed of 500 rpm, and then stand to separate the layers to obtain an upper aqueous phase and a lower organic phase.

[0024] S103: adding the lower organic phase into a batch distillation tower, and performing distillation under the conditions of normal pressure and a reflux ratio of 10:1 to obtain a distillation residue and a hydrofluoroether.

[0025] Example 2 The present application provides a purification method for obtaining high-purity hydrofluoroether, the method comprising: S201: 400g of crude HFE-374 containing 6.4wt% of unsaturated impurities and 98g of triethylamine trihydrofluoride were added to a 500ml four-necked flask equipped with a reflux tube, so that the molar ratio of unsaturated impurities in the crude HFE-374 to triethylamine trihydrofluoride was 1:3. The temperature was raised to 65°C at a stirring speed of 400rpm, and mixed and reacted at 65°C for 8h. After the reaction was completed, the mixture was cooled to room temperature to obtain a reaction solution.

[0026] S202: Add water twice the volume of the reaction solution into a four-necked flask, stir for 30 min at a stirring speed of 500 rpm, and then stand to separate the layers to obtain an upper aqueous phase and a lower organic phase.

[0027] S203: adding the lower organic phase into a batch distillation tower, and performing distillation under the conditions of normal pressure and a reflux ratio of 1:1 to obtain a distillation residue and a hydrofluoroether.

[0028] Example 3 The present application provides a purification method for obtaining high-purity hydrofluoroether, the method comprising: S301: 400g of crude HFE-449 containing 1.5wt% of unsaturated impurities and 10g of N,N-dimethylformamide hydrofluoride were added to a 500ml four-necked flask equipped with a reflux tube, so that the molar ratio of unsaturated impurities in the crude HFE-449 to N,N-dimethylformamide hydrofluoride was 1:4. The temperature was raised to 50°C at a stirring speed of 400rpm, and mixed and reacted at 50°C for 6h. After the reaction was completed, the mixture was cooled to room temperature to obtain a reaction solution.

[0029] S302: Add water twice the volume of the reaction solution into the four-necked flask, stir for 30 minutes at a stirring speed of 500 rpm, and then stand to separate the layers to obtain an upper aqueous phase and a lower organic phase.

[0030] S303: adding the lower organic phase into a batch distillation tower, and performing distillation under the conditions of normal pressure and a reflux ratio of 5:1 to obtain a distillation residue and a hydrofluoroether.

[0031] Example 4 The present application provides a purification method for obtaining high-purity hydrofluoroether, the method comprising: S401: 400 g of crude HFE-458 containing 2.8 wt% of unsaturated impurities and 16.5 g of potassium bifluoride were added to a 500 ml four-necked flask equipped with a reflux tube, so that the molar ratio of unsaturated impurities in the crude HFE-458 to potassium bifluoride was 1:4. The temperature was raised to 80° C. at a stirring speed of 400 rpm, and mixed and reacted at 80° C. for 5 hours. After the reaction was completed, it was cooled to room temperature to obtain a reaction solution.

[0032] S402: Add water twice the volume of the reaction solution into the four-necked flask, stir for 30 minutes at a stirring speed of 500 rpm, and then stand to separate the layers to obtain an upper aqueous phase and a lower organic phase.

[0033] S403: adding the lower organic phase into a batch distillation tower, and performing distillation under the conditions of normal pressure and a reflux ratio of 8:1 to obtain a distillation residue and a hydrofluoroether.

[0034] Example 5 The present application provides a purification method for obtaining high-purity hydrofluoroether, the method comprising: S501: 400g of crude HFE-449 containing 1.5wt% of unsaturated impurities, 2.6g of pyridine hydrogen fluoride salt and 7.4g of diisopropylethylamine trihydrofluoride were added to a 500ml four-necked flask equipped with a reflux tube, so that the molar ratio of unsaturated impurities in the crude HFE-449 to pyridine hydrogen fluoride salt and diisopropylethylamine trihydrofluoride was 1:3. The temperature was raised to 50°C at a stirring speed of 400rpm, and the mixture was mixed and reacted at 50°C for 6h. After the reaction was completed, the mixture was cooled to room temperature to obtain a reaction solution.

[0035] S502: Add water twice the volume of the reaction solution into the four-necked flask, stir for 30 minutes at a stirring speed of 500 rpm, and then stand to separate the layers to obtain an upper aqueous phase and a lower organic phase.

[0036] S503: adding the lower organic phase into a batch distillation tower, and performing distillation under the conditions of normal pressure and a reflux ratio of 2:1 to obtain a distillation residue and a hydrofluoroether.

[0037] The hydrofluoroethers obtained in Examples 1-5 were analyzed by gas chromatography, and the masses of the hydrofluoroethers with a purity of more than 99.8% were determined as shown in Table 1.

[0038] Table 1: Mass of hydrofluoroether in Examples 1-5 It can be seen from Table 1 that after removing unsaturated impurities in the crude hydrofluoroether by the method provided in the embodiment of the present application, hydrofluoroether with a purity higher than 99.8% can be obtained, and the quality of the hydrofluoroether with a purity higher than 99.8% is relatively high.

[0039] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A purification method for obtaining high-purity hydrofluoroether, characterized in that: include: The crude hydrofluoroether containing unsaturated impurities and the hydrofluoric acid salt are mixed and reacted at 30-150° C. for 2-10 hours, and after the reaction is completed, the mixture is cooled to room temperature to obtain a reaction solution; Add water to the reaction solution, stir, and then stand to separate into layers to obtain an upper aqueous phase and a lower organic phase; The lower organic phase is distilled to obtain distillation residue and hydrofluoroether.

2. The method for obtaining high-purity hydrofluoroether according to claim 1, characterized in that: The hydrofluoroether is prepared by reacting an alcohol or a phenol with a fluorine-containing olefin; wherein the alcohol or the phenol is an alcohol or a phenol with 1 to 10 carbon atoms and containing or not containing halogen; and the fluorine-containing olefin is an olefin with 1 to 9 carbon atoms and containing or not containing oxygen, sulfur, nitrogen, chlorine or bromine atoms.

3. The method for obtaining high-purity hydrofluoroether according to claim 1, characterized in that: The molar ratio of the unsaturated impurities in the crude hydrofluoroether to the hydrofluoride is 1:0.1-10.

4. The method for obtaining high-purity hydrofluoroether according to claim 1, characterized in that: The hydrofluoric acid salt is selected from at least one of sodium bifluoride, potassium bifluoride, and a complex of amine and hydrogen fluoride.

5. The method for purifying high-purity hydrofluoroether according to claim 1, characterized in that: The volume ratio of the reaction solution to the water is 1:0.5-2.

6. The method for purifying high-purity hydrofluoroether according to claim 1, characterized in that: The GC% content of unsaturated impurities in the crude hydrofluoroether is 0.1-20%.

7. The method for purifying high-purity hydrofluoroether according to claim 1, characterized in that: The reaction solution and the water are stirred at a speed of 50-500 rpm, and the stirring time is 10-120 min.

8. The method for purifying high-purity hydrofluoroether according to claim 1, characterized in that: The unsaturated impurities in the crude hydrofluoroether may be, but are not limited to, CH3CH2OCF=CF2, CF3CH2OCF=CF2, CF2=CHOCF2CF2H, HCF2CF2CF2CF2CH2OCF=CF2, CF2=CFCF2CF2CH2OCF2CF2H, HCF2CF2CF2CF=CHOCF2CF2H, CF2=CFCH2OCF2CF2H, HCF2CF=CHOCF2CF2H, HCF2CF=CHOCF2CF2H, HCF2CF2CH2OCF=CF2, CF=CHOCF2CFHCF3, CF3CH2OCF=CFCF3 or CF3CH2OCF2CF=CF2.

9. The method for obtaining high-purity hydrofluoroether according to claim 1, characterized in that: The distillation is an atmospheric pressure intermittent distillation, the tower bottom temperature is 2-10°C higher than the boiling point of the hydrofluoroether, the tower top temperature is ±3°C of the boiling point of the hydrofluoroether, and the reflux ratio is 10-1:1.

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