Method for reducing concentration of hydrofluoroether-olefin

Abstract

Provided is a method for effectively reducing the concentration of a hydrofluoroether-olefin (HFEO) contained in a mixture comprising a hydrofluoroether (HFE) and the HFEO. This method for reducing the concentration of an HFEO is one in which the HFE is a compound (A) represented by formula (1) and the HFEO is a compound (B) represented by formula (2), the method comprising reacting the compound (B) contained in the mixture with a compound (C) which is any of an alcohol, chlorine, and hydrogen.　(1): R2-O-R1-O-R3 (2): R2-O-R1-O-R4 In formulae (1) and (2), R1 is a C1-C4 alkylene group, R2 and R3 are each independently a C2-C4 fluoroalkyl group, and R4 is a C2-C4 fluoroalkenyl group.

Description

Method for reducing the concentration of hydrofluoroether olefins

[0001] The present invention relates to a method for reducing the concentration of hydrofluoroether (HFEO) in a mixture of HFE and hydrofluoroether olefin (HFEO).

[0002] Heat transfer media are used in a variety of heat transfer means, such as for controlling the temperature of wafers in semiconductor manufacturing, for cooling and heating semiconductor elements and electronic components, for cooling servers, and for controlling the temperature of heat pumps, heat pipes, and thermostatic baths.

[0003] Conventionally, perfluorocarbons (PFCs) have been widely used as heat transfer media because they are non-flammable and have low ozone depletion potential (ODP), etc. However, PFCs have the problem of having a high global warming potential (GWP) and a large impact on the environment due to the greenhouse effect.

[0004] For this reason, HFEs, which have low ODP, low GWP, and less impact on the environment, have been studied as heat transfer media to replace PFCs (see, for example, Patent Document 1). HFEs are generally known to be synthesized, for example, by an addition reaction of a fluoroolefin with a diol in the presence of an alkali catalyst.

[0005] Special Publication No. 2007-524737

[0006] In the synthesis method, not only the desired HFE but also HFEO, which is produced as a by-product when hydrogen fluoride in the HFE molecule is eliminated, is produced. HFEO may be thermally decomposed in a high-temperature environment, for example, at 90°C or higher, to produce an acid. When HFE is used as a heat transfer medium, if the by-product HFEO contains a large amount of impurity, it may corrode the flow path of the heat transfer medium and the surrounding device components.

[0007] From the above viewpoints, when HFE is used as a heat transfer medium, it is desirable that the concentration of HFEO, which is an impurity, be as low as possible. However, HFE and by-product HFEO have similar boiling points, and it has been difficult to separate the two by conventional methods such as distillation. Therefore, there has been a demand for a method for effectively reducing the concentration of HFEO in a mixture containing HFE and HFEO by a method other than distillation purification.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method capable of effectively reducing the concentration of HFEO in a mixture containing HFE and HFEO.

[0009] The present invention is based on the discovery that HFEO can be converted into other compounds without affecting the coexisting HFEs, thereby reducing the concentration of HFEO.

[0010] The present invention provides the following means: [1] A method for reducing the concentration of a hydrofluoroether olefin in a mixture containing a hydrofluoroether and a hydrofluoroether olefin, wherein the hydrofluoroether is a compound (A) represented by the following formula (1), the hydrofluoroether olefin is a compound (B) represented by the following formula (2), and the compound (B) in the mixture is reacted with a compound (C) selected from the group consisting of an alcohol, chlorine, and hydrogen. ２ -O-R １ -O-R ３ (1) R ２ -O-R １ -O-R ４ (2) In formulas (1) and (2), R １ is an alkylene group having 1 to 4 carbon atoms, and R ２ and R ３ are each independently a fluoroalkyl group having 2 to 4 carbon atoms, and R ４is a fluoroalkenyl group having 2 to 4 carbon atoms. [2] The method for reducing the concentration of hydrofluoroether olefins according to [1], wherein the difference in boiling points between compound (A) and compound (B) is less than 10°C. [3] The method for reducing the concentration of hydrofluoroether olefins according to [1] or [2], wherein compound (C) is alcohol or chlorine, and the difference in boiling point between compound (A) and compound (D) obtained by reacting compound (B) with the alcohol or chlorine is 15°C or more. [4] The method for reducing the concentration of hydrofluoroether olefins according to [3], wherein a crude product obtained by reacting compound (C) with the mixture is distilled to separate and remove compound (D). [5] The method for reducing the concentration of hydrofluoroether olefins according to [4], wherein the crude product or a composition obtained by distilling the crude product contains a fluorinated carboxylic acid compound, and the method comprises a step of mixing the crude product or a composition obtained by distilling the crude product with an alkaline aqueous solution to remove the fluorinated carboxylic acid compound. [6] The method for reducing a hydrofluoroether olefin concentration according to any one of [1] to [5], wherein the alcohol is a primary alcohol. [7] The method for reducing a hydrofluoroether olefin concentration according to [6], wherein the primary alcohol is methanol, ethanol, or 1-propanol. [8] The method for reducing a hydrofluoroether olefin concentration according to [1] or [2], wherein compound (C) is hydrogen. [9] The method for reducing a hydrofluoroether olefin concentration according to any one of [1] to [8], wherein compound (A) is 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane, and compound (B) is 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene.

[0011]

[10] A hydrofluoroether-containing composition having a reduced concentration of hydrofluoroether olefin, obtained by the method for reducing the concentration of hydrofluoroether olefin according to any one of [1] to [9].

[11] A heat transfer medium which is the hydrofluoroether-containing composition according to

[10] .

[12] The heat transfer medium according to

[11] , which is used for cooling or heating components in semiconductor manufacturing equipment.

[0012] According to the present invention, the concentration of HFEO in a mixture containing HFE and HFEO can be effectively reduced.

[0013] A method for reducing the concentration of HFO according to an embodiment of the present invention (hereinafter also referred to as the present embodiment) is a method for reducing the concentration of HFEO in a mixture containing HFE and HFEO, characterized in that the HFE is a compound (A) represented by the following formula (1), the HFEO is a compound (B) represented by the following formula (2), and compound (B) in the mixture is reacted with any one compound (C) selected from alcohol, chlorine, and hydrogen. ２ -O-R １ -O-R ３ (1) R ２ -O-R １ -O-R ４ (2) In formulas (1) and (2), R １ is an alkylene group having 1 to 4 carbon atoms, and R ２ and R ３ are each independently a fluoroalkyl group having 2 to 4 carbon atoms, and R ４ is a fluoroalkenyl group having 2 to 4 carbon atoms.

[0014] According to this embodiment, by using alcohol, chlorine, or hydrogen as a compound to be reacted with a mixture containing HFE and HFEO, it is possible to effectively convert HFEO into other compounds and reduce the concentration of HFEO without affecting the HFE.

[0015] The HFE in this embodiment is a compound (A) represented by the following formula (1): ２ -O-R １ -O-R ３ (1)

[0016] R １ is an alkylene group having 1 to 4 carbon atoms, preferably 2 to 4 carbon atoms, and more preferably 2 to 3 carbon atoms. The carbon chain may be linear or branched, and is preferably linear.

[0017] R ２ and R ３are each independently a fluoroalkyl group having 2 to 4 carbon atoms, and may be the same or different. From the viewpoints of fluidity as a heat transfer medium and ease of production, the number of carbon atoms is 2 to 4, preferably 3 or 4. The carbon chain of the fluoroalkyl group may be linear or branched, and is preferably linear. R ２ and R ３ The fluoroalkyl group preferably has one hydrogen atom, and this hydrogen atom may be bonded to any carbon atom. ２ or R ３ is preferably a hydrogen atom (β hydrogen) bonded to the second carbon atom from the oxygen atom (etheric oxygen atom) adjacent to the

[0018] The HFEO in this embodiment is a compound (B) represented by the following formula (2): ２ -O-R １ -O-R ４ (2)

[0019] R in formula (2) １ and R ２ is R in formula (1). １ and R ２ is the same as

[0020] R ４ is a fluoroalkenyl group having 2 to 4 carbon atoms, and from the viewpoints of fluidity as a heat transfer medium and ease of production, the carbon number is 2 to 4, preferably 3 or 4. The carbon chain of the fluoroalkenyl group may be linear or branched, and is preferably linear. ４ In terms of fluidity as a heat transfer medium, ease of production, etc., it is preferable that one of the carbon atoms constituting the carbon-carbon double bond of the fluoroalkenyl group R be bonded to the adjacent oxygen atom. ４ The fluoroalkenyl group may have a hydrogen atom, but is preferably a perfluoroalkenyl group.

[0021] The mixture containing compound (A) and compound (B) may contain components other than compound (A) and compound (B) as impurities, but from the viewpoint of effectively reducing the concentration of HFEO, it is preferable that the amount of other components be as small as possible. From the viewpoint of purification efficiency, the content of other components in the mixture is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 0% by mass.

[0022] The method for reducing the concentration of HFEO of this embodiment (hereinafter sometimes referred to as the method of this embodiment) can be particularly effective when, for example, the difference in boiling points between compound (A) and compound (B) is less than 10°C, and the boiling points of the two are similar, making conventional separation methods such as distillation difficult. When the boiling points of compound (A) and compound (B) are similar, it is difficult to separate compound (A) and compound (B) by distillation. However, according to the method of this embodiment, the concentration of compound (B) in a mixture of compound (A) and compound (B) can be reduced by converting compound (B), which is HFEO, into another compound. Note that the boiling point referred to in this specification is the boiling point at a pressure of 0.1 MPa (1 atm).

[0023] A specific example of a combination of compound (A) and compound (B) is 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane (CF ３ CHFCF ２ OCH ２ CH ２ OCF ２ CHFCF ３ ;HFE-77-12) and 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene (CF ３ CF = CFOCH ２ CH ２ OCF ２ CHFCF ３ ) combination; 1,1,2,2-tetrafluoro-1-[2-(1,1,2,2-tetrafluoroethoxy)ethoxy]ethane (CHF ２ CF ２ OCH ２ CH ２ OCF２ CHF ２ ) and 1,2-trifluoro-1-[2-(1,1,2,2-tetrafluoroethoxy)ethoxy]-1-ethane (CF ２ = CFOCH ２ CH ２ OCF ２ CHF ２ ) and the like. The method of the present embodiment uses, among these, a combination of HFE-77-12 and 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene (CF ３ CF = CFOCH ２ CH ２ OCF ２ CHFCF ３ (Hereinafter referred to as "HF-free product") (boiling points of both are 164°C) is more effective.

[0024] Compound (C) is an alcohol, chlorine, or hydrogen. By reacting compound (C) with the carbon-carbon double bond of compound (B), compound (B) is converted to compound (D).

[0025] When compound (C) is an alcohol, compound (B) is converted to compound (D) in which a fluorine atom bonded to one of the carbon atoms having a carbon-carbon double bond is substituted with an alkoxy group. In the reaction for converting compound (B) to compound (D), which is such an alkoxy-substituted HFEO, the alcohol used as compound (C) is preferably a primary alcohol, from the viewpoint of preventing the occurrence of an elimination reaction of hydrogen fluoride from compound (A) in the mixture. Among these, methanol, ethanol, or 1-propanol are preferred, and methanol is more preferred, from the viewpoints of versatility, reactivity, and the like.

[0026] For example, when compound (A) is HFE-77-12, compound (B) is a HF-free compound, and compound (C) is methanol, compound (D) is a methoxy-substituted compound of the HF-free compound, 1,3,3,3-hexafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-2-methoxy-1-propene (CF ３ C(OCH ３ ) = CFOCH ２ CH ２ OCF ２ CHFCF ３ )

[0027] In order to facilitate the distillation separation of the alkoxy-substituted compound (D) to obtain a high-purity compound (A), the difference between the boiling point of the compound (D) and the boiling point of the compound (A) is preferably 15° C. or more, more preferably 20° C. or more, and even more preferably 25° C. or more. Either the boiling point of the alkoxy-substituted compound (D) or the boiling point of the compound (A) may be higher, but the boiling point of the compound (D) is usually higher than the boiling point of the compound (A).

[0028] Because the alkoxy-substituted compound (D) and compound (A) have such a boiling point difference, compound (D) can be separated and removed by distilling the crude product obtained by reacting compound (C) with a mixture containing compound (A) and compound (B), and high-purity compound (A) can be obtained as a composition after distillation purification. The composition after distillation purification is obtained as high-purity compound (A) having a content of compound (B) of preferably less than 0.1 mol%, more preferably 0.05 mol% or less, and even more preferably 0.03 mol% or less.

[0029] When compound (C) is an alcohol, the amount of the alcohol used is preferably 1.0 to 20.0 molar equivalents, more preferably 2.0 to 18.0 molar equivalents, and even more preferably 3.0 to 15.0 molar equivalents, relative to compound (B).

[0030] From the viewpoint of efficient reaction, this reaction is carried out preferably at −20° C. or higher, more preferably at −10° C. or higher, and even more preferably at 0° C. or higher, and from the viewpoint of suppressing the formation of by-products, the reaction is carried out preferably at 80° C. or lower, more preferably at 70° C. or lower, and even more preferably at 60° C. or lower. The reaction can be carried out at normal pressure, and is preferably carried out in the presence of a base catalyst.

[0031] Examples of base catalysts include potassium hydroxide, sodium hydroxide, potassium bicarbonate, sodium bicarbonate, potassium carbonate, sodium carbonate, and triethylamine. Of these, potassium hydroxide is preferred from the viewpoint of efficient reaction. The amount of base catalyst used is preferably 1.0 to 10.0 molar equivalents, more preferably 2.0 to 8.0 molar equivalents, and even more preferably 3.0 to 5.0 molar equivalents, relative to compound (B). Furthermore, the base catalyst is preferably added as an aqueous solution from the viewpoint of uniform mixing into the reaction system. When an aqueous potassium hydroxide solution is used, the concentration of the aqueous solution is preferably 10 to 70% by mass, more preferably 15 to 60% by mass, and even more preferably 20 to 50% by mass.

[0032] When compound (C) is chlorine, compound (B) is converted to compound (D) in which chlorine atoms are added to both carbon atoms having a carbon-carbon double bond. For example, when compound (A) is HFE-77-12 and compound (B) is a fluorine-free compound, compound (D) is 1,1,1,2,3-pentafluoro-2,3-dichloro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane (CF ３ CFClCFClOCH ２ CH ２ OCF ２ CHFCF ３ )

[0033] Compound (D), which is a chlorine adduct HFE obtained by conversion of compound (B), can be separated by distillation to easily obtain high-purity compound (A), so the difference in boiling point between compound (D) and compound (A) is preferably 15° C. or more, more preferably 20° C. or more, and even more preferably 25° C. or more. Either the boiling point of compound (D), which is a chlorine adduct, or the boiling point of compound (A) may be higher, but the boiling point of compound (D) is usually higher than the boiling point of compound (A).

[0034] Because the chlorine adduct compound (D) and compound (A) have such a boiling point difference, compound (D) can be separated and removed by distilling a crude product obtained by reacting compound (C) with a mixture containing compound (A) and compound (B), and high-purity compound (A) can be obtained as a composition after distillation purification. The composition after distillation purification is obtained as high-purity compound (A) having a compound (B) content of preferably less than 0.1 mol %, more preferably 0.05 mol % or less, and even more preferably 0.03 mol % or less.

[0035] When compound (C) is chlorine, the amount of chlorine used is preferably 1.0 to 2.0 molar equivalents, more preferably 1.05 to 1.75 molar equivalents, and even more preferably 1.1 to 1.5 molar equivalents, relative to compound (B).

[0036] From the viewpoint of efficient reaction, this reaction is carried out preferably at −20° C. or higher, more preferably at −10° C. or higher, and even more preferably at 0° C. or higher, and from the viewpoint of suppressing the formation of by-products, the reaction is carried out preferably at 80° C. or lower, more preferably at 70° C. or lower, and even more preferably at 60° C. or lower. The reaction can be carried out at normal pressure, and from the viewpoint of suppressing the formation of by-products, it is preferable to carry out the reaction in the dark.

[0037] When compound (C) is hydrogen, compound (B) is converted to compound (D) in which hydrogen atoms are added to both carbon atoms having a carbon-carbon double bond. For example, when compound (A) is HFE-77-12 and compound (B) is a HF-free compound, compound (D) is 1,1,1,2,3-pentafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane (CF ３ CHFCHFOCH２ CH ２ OCF ２ CHFCF ３ )

[0038] Compound (D), which is a hydrogenated HFE obtained by conversion of compound (B), usually has a boiling point similar to that of compound (A) and is difficult to separate from compound (A) by distillation. However, even when compound (D) is used as a heat transfer medium in the coexistence with compound (A), compound (D) does not corrode the flow path of the heat transfer medium and the surrounding equipment components due to the generation of acid, etc., as does compound (B).

[0039] When compound (C) is hydrogen, the amount of hydrogen used is, from the viewpoint of safety, preferably 1.0 to 100 molar equivalents, more preferably 1.0 to 50 molar equivalents, and even more preferably 1.0 to 10 molar equivalents, relative to compound (B).

[0040] From the viewpoint of efficient reaction, this reaction is carried out preferably at -20°C or higher, more preferably at -10°C or higher, and even more preferably at 0°C or higher, and from the viewpoint of suppressing the formation of by-products, the reaction is carried out preferably at 80°C or lower, more preferably at 70°C or lower, and even more preferably at 60°C or lower. From the viewpoint of facilitating the introduction of hydrogen into the liquid phase, the reaction is preferably carried out under pressure, but may be carried out under normal pressure. Furthermore, the reaction is preferably carried out in the presence of a hydrogenation catalyst.

[0041] Examples of the hydrogenation catalyst include metal catalysts such as iridium, nickel, palladium, platinum, rhodium, and ruthenium. From the viewpoints of catalytic effect and cost, the amount of the hydrogenation catalyst used is preferably 0.001 to 50 mass%, more preferably 0.005 to 30 mass%, even more preferably 0.01 to 10 mass%, and particularly preferably 0.01 to 1 mass%, relative to the total amount of compound (A) and compound (B). From the viewpoint of easy availability, the hydrogenation catalyst is preferably palladium-activated carbon (containing 10 mass% Pd) or the like.

[0042] A crude product obtained by reacting a mixture containing compound (A) and compound (B) with hydrogen is purified by distillation to obtain a mixture containing compound (A) and compound (D) but not compound (B).

[0043] As the compound (C), alcohol is preferred from the viewpoint of safety and ease of handling, compared with chlorine or hydrogen, which are handled as gases. In addition, hydrogen is preferably reacted in the presence of a metal catalyst, particularly a noble metal catalyst, and considering that it is difficult to separate the resulting hydrogen adduct from the compound (A) by distillation, alcohol or chlorine is preferred as the compound (C) in order to obtain a high-purity compound (A). In addition, alcohol is more preferred from the viewpoint of reactivity, compared with chlorine, which may be reactive with the compound (A).

[0044] The crude product obtained by reacting a mixture containing compound (A) and compound (B) with compound (C) and the composition obtained by distillative purification of the crude product (hereinafter collectively referred to as the crude product, etc.) may contain, as impurities, a fluorinated carboxylic acid compound, etc. In this case, by mixing the crude product, etc. with an alkaline aqueous solution, a high-purity compound (A) from which the fluorinated carboxylic acid compound has been removed can be easily obtained.

[0045] The alkaline aqueous solution is not particularly limited, and examples thereof include aqueous solutions of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, potassium hydroxide, sodium hydroxide, etc. The temperature when mixing the crude product, etc. with the alkaline aqueous solution is preferably 40°C or higher, more preferably 60°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher, from the viewpoint of increasing the efficiency of removing the fluorinated carboxylic acid compound. Furthermore, from the viewpoint of suppressing decomposition of compound (A), the temperature is preferably 180°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower. The mixing time is preferably 1 to 10 hours. From the viewpoint of increasing the efficiency of removing the fluorinated carboxylic acid compound, it is preferable to mix the crude product, etc. with the alkaline aqueous solution while stirring. When mixing the crude product, etc. with the alkaline aqueous solution, compound (D) can be separated and removed by distilling the organic layer of the resulting mixture, and a highly pure compound (A) can be obtained as a distilled purified product.

[0046] Examples of a method for synthesizing a mixture containing compound (A) and compound (B) include a method in which a fluoroolefin and a diol are subjected to an addition reaction in the presence of an alkali catalyst such as potassium carbonate, followed by an elimination reaction of hydrogen fluoride in the presence of a strong base such as an alkali metal alkoxide.

[0047] The method for reducing the concentration of HFEO according to the present embodiment described above provides an HFE-containing composition containing compound (A) as the main component and with a reduced concentration of compound (B). Such an HFE-containing composition is suitable for a wide range of applications, including cleaning agents, solvents, foaming agents, aerosols, working fluids for binary power generation such as heat pipes and factory waste heat recovery, storage solutions for electronic components, and media for gross leak tests, thermal shock tests, liquid burn-in tests, and voltage resistance tests for electronic components, and is particularly suitable as a heat transfer medium. For example, it can be used as a heat transfer medium for wafer temperature control in semiconductor manufacturing, cooling and heating of semiconductor elements and electronic components, cooling of servers, heat pumps, heat pipes, thermostatic baths, and the like. Because compound (A) has excellent insulating properties, it is suitable for cooling or heating components in semiconductor manufacturing equipment, and can particularly withstand harsh conditions of high electric fields and high temperatures, such as plasma-based dry etching processes in semiconductor manufacturing.

[0048] The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.

[0049] The reaction products were identified by proton nuclear magnetic resonance ( １ H NMR) spectrum, fluorine-19 nuclear magnetic resonance ( １９ F NMR) spectrum and gas chromatography mass spectrometry (GC-MS (column used: "DB-1301", length 60 m, inner diameter 250 μm, thickness 1 μm; manufactured by Agilent Technologies, Inc.)).

[0050] [Synthesis Example 1] 223 g of potassium carbonate (manufactured by Junsei Chemical Co., Ltd.), 200 g of ethylene glycol (manufactured by Junsei Chemical Co., Ltd.), and 400 g of anhydrous acetonitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a stainless steel autoclave (internal volume 2.1 liters) equipped with a stirrer, and the mixture was kept sealed at 20 ° C. The contents of the autoclave were stirred, and 966 g of hexafluoropropene (manufactured by AGC Inc.) was added in a gaseous state over 6 hours. After reaction at 20 ° C. for 1 hour, the reaction crude liquid in the autoclave was recovered by filtration. The recovered reaction crude liquid was phase-separated, washed with water, dried over molecular sieve 3A (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and then purified by distillation to obtain a mixture of HFE-77-12 and HF-free form (HFE-77-12 95.3 mol%, by-product resulting from the elimination of hydrogen fluoride from HFE-77-12 4.7 mol%).

[0051] [Example 1] Reaction with Alcohol 200 g of the mixture obtained in Synthesis Example 1, 10 g of methanol (manufactured by Junsei Chemical Co., Ltd.), and 10 g of a 48% by mass aqueous potassium hydroxide solution (manufactured by Kanto Chemical Co., Ltd.) were placed in a stainless steel autoclave (internal volume 2.1 liters) equipped with a stirrer, and the mixture was stirred at 20°C in a sealed state. After reacting for 3 hours, the crude reaction liquid in the autoclave was phase-separated, washed with distilled water, and then dried over Molecular Sieve 3A (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.; the same applies hereinafter), to obtain a crude product (HFE-77-12 95.3 mol%, HF-free product 0.01 mol%, methoxy-substituted product 4.6 mol%, fluorine-containing carboxylic acid 0.05 mol%, other components 0.04 mol%). The crude product was then distilled to obtain a purified product (HFE-77-12 99.99 mol%, HF-free product 0.01 mol%).

[0052] [Example 2] Reaction with Chlorine 200 g of the mixture obtained in Synthesis Example 1 and 2.3 g of chlorine (manufactured by Toagosei Co., Ltd.) were placed in a stainless steel autoclave (internal volume 2.1 liters) equipped with a stirrer, sealed, and stirred at 20°C. After reacting for 1 hour, the crude reaction liquid in the autoclave was recovered, neutralized with an aqueous potassium bicarbonate solution to cause phase separation, and dried over molecular sieves 3A to obtain a crude product (95.1 mol% HFE-77-12, 0.01 mol% HF-free compounds, 4.6 mol% chlorine adducts, 0.29 mol% other components). The crude product was then distilled to obtain a purified product (99.99 mol% HFE-77-12, 0.01 mol% HF-free compounds).

[0053] [Example 3] Reaction with hydrogen 200 g of the mixture obtained in Synthesis Example 1, 150 g of ethyl acetate (manufactured by Junsei Chemical Co., Ltd.), and 0.3 g of palladium-activated carbon (containing 10% by mass of Pd) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a stainless steel autoclave (internal volume 2.1 liters) equipped with a stirrer, and the autoclave was kept sealed and at 20°C. The contents of the autoclave were stirred, and hydrogen gas was blown in at 10 mL / min for 1 hour. After stirring for another 1 hour to allow the reaction, the reaction crude liquid in the autoclave was recovered by filtration. The recovered reaction crude liquid was dried over molecular sieves 3A and then distilled to obtain a mixture of HFE-77-12 and a hydrogenated product (HFE-77-12 95.3 mol%, hydrogenated product 4.7 mol%).

[0054] Example 4 To the crude product obtained in Example 1, 100 g of a 24% by mass aqueous potassium hydroxide solution was added, the mixture was stirred at 120°C for 3 hours, the mixture was subjected to phase separation and washing with distilled water, and dried over molecular sieves 3A to obtain an organic layer (HFE-77-12 95.3 mol%, HF-free compounds 0.01 mol%, methoxy-substituted compounds 4.6 mol%, fluorine-containing carboxylic acid not detected). The organic layer was then distilled to obtain a purified product (HFE-77-12 99.99 mol%, HF-free compounds 0.01 mol%).

[0055] In Examples 1 to 4, it was confirmed that the concentration of the HF-free substance was reduced from the mixture of HFE-77-12 and the HF-free substance.

Claims

1. A method for reducing the concentration of a hydrofluoroether olefin in a mixture containing a hydrofluoroether and a hydrofluoroether olefin, wherein the hydrofluoroether is a compound (A) represented by the following formula (1), and the hydrofluoroether olefin is a compound (B) represented by the following formula (2), and the compound (B) in the mixture is reacted with a compound (C) selected from the group consisting of an alcohol, chlorine, and hydrogen. ２ -O-R １ -O-R ３ (1) R ２ -O-R １ -O-R ４ (2) In formulas (1) and (2), R １ is an alkylene group having 1 to 4 carbon atoms, R ２ and R ３ are each independently a fluoroalkyl group having 2 to 4 carbon atoms, and R ４ is a fluoroalkenyl group having 2 to 4 carbon atoms.

2. The method for reducing the concentration of hydrofluoroether olefin according to claim 1, wherein the difference in boiling point between compound (A) and compound (B) is less than 10°C.

3. The method for reducing the concentration of hydrofluoroether olefin according to claim 1, wherein compound (C) is an alcohol or chlorine, and the difference in boiling point between compound (A) and compound (D) obtained by reacting compound (B) with the alcohol or chlorine is 15°C or more.

4. The method for reducing the concentration of hydrofluoroether olefin according to claim 3, wherein the crude product obtained by reacting the mixture with compound (C) is distilled to separate and remove compound (D).

5. The method for reducing the concentration of hydrofluoroether olefin according to claim 1, wherein the alcohol is a primary alcohol.

6. The method for reducing the concentration of hydrofluoroether olefin according to claim 5, wherein the primary alcohol is methanol, ethanol or 1-propanol.

7. The method for reducing the concentration of hydrofluoroether olefin according to claim 1, wherein compound (C) is hydrogen.

8. The method for reducing the concentration of hydrofluoroether olefin according to claim 1, wherein compound (A) is 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane and compound (B) is 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene.

9. A hydrofluoroether-containing composition having a reduced concentration of hydrofluoroether olefin, obtained by the method for reducing the concentration of hydrofluoroether olefin according to any one of claims 1 to 8.

10. A heat transfer medium which is the hydrofluoroether-containing composition of claim 9.

11. The heat transfer medium according to claim 10, which is used to cool or heat components in semiconductor manufacturing equipment.