JP2006306726A - Method for producing fluorinated ether - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a hydrofluorocarbon (HFE) which is promising as a substitute for CFC, HCFC, HFC or PFC due to its relatively small stratosphere ozone-depleting capacity and global warming capacity by using, as a raw material, a substance available on an industrial scale or a substance producible from a raw material available on an industrial scale. <P>SOLUTION: This method for producing a fluorinated ether comprises reacting a ≥2C fluorinated olefin having at least one fluorine atom with a ≥1C alcohol in the presence of a potassium fluoride/activated alumina, potassium hydroxyide/activated alumina or sodium hydroxide/activated alumina solid catalyst supporting potassium fluoride, potassium hydroxide or sodium hydroxide on activated alumina. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a fluorinated ether useful as a functional material such as a cleaning agent, a solvent, a refrigerant, an aerosol propellant, a plastic foaming agent, a heat transfer medium, and a particle removing agent.

  Conventionally, chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), hydrofluorocarbon (HFC) or perfluorocarbon (PFC) has been used for cleaning agents, solvents, refrigerants, aerosol propellants, plastic blowing agents, heat transfer media, particle removal agents, etc. ) Etc. have been used.

  However, when these CFCs, HCFCs, HFCs or PFCs are released into the global environment, they are known to have adverse effects on the global environment such as the destruction of the stratospheric ozone layer and global warming. Search is in progress. Hydrofluoroether (HFE) is a promising alternative because it has a relatively small destruction of the stratospheric ozone layer and global warming ability compared to CFC, HCFC, HFC or PFC.

  1-methoxy-1,1,2,2-tetrafluoroethane (hereinafter abbreviated as HFE-254pc) according to the present invention is a compound having hydrogen, fluorine and oxygen in the molecule and belonging to HFE. The following manufacturing methods are known. Non-Patent Document 1 to Non-Patent Document 3 describe a method for producing HFE-254pc in which methanol and sodium methoxide are reacted with tetrafluoroethylene (hereinafter abbreviated as TFE), and Patent Documents 1 to 5 include an alkali catalyst. A method for producing HFE-254pc in which lower TFE and methanol are reacted is disclosed. As a method for producing 1-ethoxy-1,1,2,2-tetrafluoroethane, which is a compound belonging to HFE, a reaction of sodium ethoxide with TFE in an ethanol solvent (Patent Document 6) or 1,2-dibromo-1 , 1,2,2-tetrafluoroethane and ethanol are reacted in the presence of a KOH catalyst (Patent Document 7).

Regarding a solid catalyst, for example, KF / Al ₂ O ₃ is known to undergo an intramolecular Michael type addition reaction in a hydrocarbon compound to generate an ether bond (Non-patent Document 4). Non-Patent Document 5 reports that crown ether can be obtained by reaction of diol and ditosylate in acetonitrile solvent in the presence of KF / Al ₂ O ₃ . However, a method for synthesizing a fluorinated ether by reacting a fluorinated olefin not containing a carbonyl group with an alcohol in the presence of KF / Al ₂ O ₃ is not known.
J. et al. Amer, Chem. Soc. , 70, 431 (1947) J. et al. Gen. Chem. USSR, 37, 797 (1965) J. et al. Chem. Soc. C, 2, 395 (1967) P. Laszlo “Preparative Chemistry Using Supported Reagents” Academic Press INC (1987) p. See 287 J. et al. Yamawaki et al., Chem. Lett. 533 (1980) US Pat. No. 3,663,715 US Pat. No. 3,609,196 US Pat. No. 3,769,434 Specification US Pat. No. 3,862,241 Specification JP-A-8-92162 U.S. Pat. No. 2,409,274 Japanese Patent Publication No.42-21323

  Until now, the method of obtaining a fluorinated ether by adding an alcohol to a fluorinated olefin has been carried out in the liquid phase in the presence of a base catalyst such as potassium hydroxide or a metal alkoxide. However, in these methods, the reaction rate is low, and the reaction product and the catalyst become uniform, so that a complicated separation operation is required. Therefore, they are not necessarily suitable as industrially applicable methods. For this reason, there has been a demand for an industrially useful method for producing a fluorinated ether using a catalyst having a high reaction rate and allowing easy separation of the reaction product and the catalyst. An object of the present invention is to provide an industrially useful method for producing a fluorinated ether using a material which can be obtained on an industrial scale or which can be produced relatively easily from a raw material available on an industrial scale. .

  In order to solve the above-mentioned problems, the present inventors have prepared a raw material and a reaction product as a catalyst for easily separating the reaction product and the catalyst in obtaining a fluorinated ether by addition reaction of alcohol with a fluorinated olefin. As a result of diligent investigation focusing on a solid catalyst that is a heterogeneous catalyst, a catalyst in which an alkali metal or alkaline earth metal compound is supported on activated alumina as a solid catalyst, in particular, alkali fluoride or alkali hydroxide is supported on activated alumina. The present invention has been found to be suitable for a reaction system using the prepared catalyst.

  That is, the present invention is a method for producing a fluorinated ether, comprising reacting a fluorinated olefin having 2 or more carbon atoms containing at least one fluorine atom with an alcohol having 1 or more carbon atoms in the presence of a solid catalyst.

  In addition, the present invention is the above-described method for producing a fluorinated ether, wherein the solid catalyst is a catalyst in which an alkali metal or an alkaline earth metal compound is supported on activated alumina.

  Further, in the present invention, the solid catalyst is potassium fluoride / activated alumina, potassium hydroxide / activated alumina or sodium hydroxide / activated alumina in which potassium fluoride, potassium hydroxide or sodium hydroxide is supported on activated alumina. This is a method for producing the above fluorinated ether.

  Furthermore, the present invention is the above production method wherein the fluorinated olefin is tetrafluoroethylene, the alcohol is methanol, and the fluorinated ether is 1-methoxy-1,1,2,2-tetrafluoroethane.

  When the method using the heterogeneous solid catalyst of the present invention is used, the reaction rate is remarkably increased as compared with the reaction of the liquid phase homogeneous system, and the product and the catalyst are easily separated. Energy and environmental load can be reduced.

  That is, according to the present invention, a fluorinated ether can be produced from a material that can be obtained on an industrial scale or that can be produced relatively easily from a raw material available on an industrial scale.

  The fluorinated olefin used as the starting material of the present invention may be an olefin having 2 or more carbon atoms having 1 or more atoms in the molecule, but a compound having about 2 to 8 carbon atoms is preferable. This is because if the raw material olefin has too many carbon atoms, the viscosity of the reaction system increases, which may hinder the catalytic reaction. Specifically, tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, difluoroethylene, fluoroethylene, chlorofluoroethylene, bromofluoroethylene, iodofluoroethylene, hexafluoropropene, 1-chloro-3,3,3-tri Fluoropropene, 1,3,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, 1,1,1,3,3-pentafluoropropene, 3-fluoro-1-propene, 1-bromo -3,3,3-trifluoropropene, hexafluorobutadiene, 2-chloro-1,1,1,4,4,4-hexafluoro-2-butene, 1,1,2,2-tetrafluoroethylallyl Ether, perfluoroheptene-1, hexafluorocyclobutene, etc. La fluoroethylene, hexafluoropropene are particularly preferred.

  The alcohol may be an alcohol having 1 or more carbon atoms, such as methanol, ethanol, propanol, ethylene glycol, diethylene glycol, trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-propanol. , Pentafluoropropanol, phenol, anisole, 1,4-butanediol and the like.

  The solid catalyst used in the present invention is preferably a catalyst in which an alkali metal or an alkaline earth metal compound is supported on activated alumina. Hereinafter, an alkali metal or alkaline earth metal compound compound (eg, fluoride, hydroxide, carbonate) may be simply abbreviated as a metal compound (metal fluoride, metal hydroxide, metal carbonate). Examples of the cation portion of the metal compound to be supported include alkali metals such as lithium, sodium, potassium, rubidium, and cesium, and alkaline earth metals such as magnesium, calcium, and barium. Among these, potassium and sodium are preferable. .

  Examples of the anion portion of the metal compound to be supported include halogens such as fluorine, chlorine, iodine and bromine, hydroxyl groups, sulfate groups, amide groups, alkoxyl groups, phosphate groups, carbonate groups, nitrile groups and the like.

  Among them, a catalyst in which a metal fluoride, a metal hydroxide, or a metal carbonate is supported on activated alumina is preferable.

  The method for preparing the catalyst is not particularly limited. In a solution in which the above alkali metal or alkaline earth metal such as metal fluoride, metal hydroxide, or metal carbonate is dissolved in a solvent such as water, alcohol, ketone, or nitrile. It is obtained by immersing activated alumina, then removing the solvent under reduced pressure using an evaporator or the like while heating and drying.

  Specifically, metal fluoride, metal hydroxide or metal carbonate used for catalyst preparation is lithium fluoride, potassium fluoride, sodium fluoride, rubidium fluoride, cesium fluoride, magnesium fluoride, calcium fluoride, Examples of the hydroxide include lithium hydroxide, potassium hydroxide, sodium hydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide. It is done. Examples of the carbonate include lithium carbonate, potassium carbonate, sodium carbonate, rubidium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, and barium carbonate. Furthermore, a metal alkali such as sodium or potassium or potassium amide may be added.

  The supported amount of the metal fluoride, metal hydroxide or metal carbonate used for the catalyst preparation is 1 to 200 parts by weight, preferably 5 to 100 parts by weight, with respect to 100 parts by weight of alumina. Two or more kinds of metal fluorides, metal hydroxides or alkali carbonates can be supported, and the catalytic activity can be adjusted.

As the activated alumina carrier of the present invention, γ-alumina having a large pore volume and a large specific surface area is suitable. The specific surface area of the activated alumina is preferably 100 to 400 m ² / g.

  The production method of the present invention can be carried out by any method such as “a method in which fluorinated olefin is continuously blown into liquid alcohol”, “a method in which both are charged into a reactor and carried out in a batch system”. It is also possible to use “a method in which a liquid or gaseous alcohol and a fluorinated olefin are introduced together and a product is continuously extracted”. For example, in the reaction of methanol and TFE, a method can be used in which a predetermined amount of methanol and a solid catalyst are charged in a pressure resistant reactor, and a predetermined amount of TFE is charged and then subjected to the reaction. In this case, since the pressure decreases with the progress of the reaction, the reaction can be continued by charging TFE corresponding to the pressure decrease again.

  Furthermore, using a solid catalyst in which KF is supported on activated alumina, methanol and TFE can be vaporized, a gas phase heterogeneous reaction can be performed, and the product can be continuously taken out. In this case, the reaction tube filled with the prepared solid catalyst is adjusted to an appropriate temperature with an electric furnace, and the raw material is introduced therein to proceed with the reaction. The raw material fluorinated olefin and alcohol are previously heated in a vaporizer and introduced into the reaction tube as a gas. The reaction product can be captured and recovered at a reactor outlet by a cooling trap such as an ice water bath trap or a dry ice-acetone bath trap.

  In the production method of the present invention, the reaction reacts with 1 mol of alcohol per 1 mol of fluorinated olefin. However, it is industrially adjusted to increase the consumption of high fluorinated olefin in terms of cost by charging a large amount of alcohol. Is advantageous. The molar ratio of fluorinated olefin / alcohol is (1/1) to (1/200), preferably (1/1) to (1/100), more preferably (1/1) to (1 / 20), fluorinated olefins can be added as the reaction proceeds.

  In the method of the present invention, the catalyst concentration can be any concentration as long as the reaction proceeds. In the case of a batch system, the concentration of the alkali metal or alkaline earth metal compound is 0.1 to 100 mol%, preferably 1 as the concentration of the alcohol. ˜50 mol%.

  A solvent can also be used in the method of the present invention. The solvent is not particularly limited as long as it does not adversely affect the reaction, but in the case of a liquid phase heterogeneous reaction, a solvent that promotes dissolution of the reaction substrate, dimethyl sulfoxide, glyme, diglyme, tetraglyme, acetonitrile, N, N-dimethyl Examples include acetamide, N, N-dimethylformamide, N-methylpyrrolidone, sulfolane, tetrahydrofuran, hexane, pentane, dibutyl ether, and trimethoxymethane.

  The reactor and the reaction tube may be made of a material having heat resistance and corrosion resistance to raw materials and products, and glass, stainless steel, hastelloy, monel, platinum and the like are preferable. It can also be made from materials lined with these.

  The reaction temperature used by the manufacturing method of this invention is 20 to 200 degreeC, Preferably it is 50 to 100 degreeC. At temperatures lower than 20 ° C., the reaction rate is very small and impractical. In addition, when the reaction temperature exceeds 200 ° C., the progress of the reaction is hindered and by-products such as vinyl ether are generated, which is not preferable. The reaction temperature when the reaction is carried out in the gas phase varies depending on the fluorinated olefin and alcohol used, but is within the above temperature range and at a temperature at which the fluorinated olefin and alcohol become gas.

  The reaction pressure is basically selected as a function of safety, handling, equipment and other practical considerations and can be performed at about 0.01-2.0 MPa, preferably 0.1-1.0 MPa.

  When the present invention is carried out in the gas phase, the contact time of the reaction can usually be 0.1 to 300 seconds, but 1 to 60 seconds is preferable from the viewpoint of productivity. If the contact time is too short, the reaction does not proceed sufficiently, and if it is too long, the size of the reactor becomes excessive and side reactions may occur, which is not preferable.

  The crude product containing the fluorinated ether treated by the method of the present invention and flowing out of the reactor is purified by a known method. When the batch method is used, the reaction product and the solid catalyst can be easily separated by simple filtration. Therefore, the reaction product is collected in a purification step after filtration. Can be subjected to a purification step.

  Although the purification method is not limited, for example, in the case of a mixture of methanol and HFE-254pc, an azeotropic composition is formed. Therefore, after azeotropic distillation is first performed, the azeotropic composition is washed with water to remove alcohol, and then dried. It can be purified by subjecting it to precision distillation to remove organic impurities.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

[Catalyst Preparation Example 1]
30 g of activated alumina (NKH3-24 manufactured by Sumika Alchem: particle size 2 to 4 mm, specific surface area 340 m <2> / g) was weighed, and the powder adhering to the surface was washed with water. 20 g of potassium fluoride was dissolved in 20 g of water to prepare a 50% aqueous solution. The washed activated alumina was immersed in a 50% aqueous solution and allowed to stand overnight. After filtration, it was dried under reduced pressure at 80 ° C. for 2 hours by an evaporator. The dried activated alumina was taken out and used as a catalyst.

[Catalyst Preparation Example 2]
A catalyst was prepared in the same manner as in Preparation Example 1 except that potassium hydroxide was used instead of potassium fluoride.

[Example 1]
Using a pressure resistant reactor made of 100 ml SUS316L having a pressure gauge and a gas inlet, the reaction was performed using KF / Al ₂ O ₃ shown in Preparation Example 1 as a catalyst. To the reactor, 2.5 g of KF / Al ₂ O ₃ and 10 g of methanol were added, cooled in a dry ice-acetone bath and deaerated inside the reactor, and 2.3 g of TFE was introduced from the gas inlet. When the reaction temperature was set to 80 ° C., the pressure was 0.46 MPa. Since the pressure became 0.19 MPa 3 hours after the start of the reaction, the reactor was placed in an ice bath and cooled, and the contents were taken out. The recovered organic matter was 11.7 g (recovery rate 95.1%).

  As a result of analyzing the recovered organic matter by gas chromatography, the HFE-254pc yield based on TFE was 71.3%.

[Example 2]
The reaction was carried out in the same manner as in Example 1 using KOH / Al ₂ O ₃ shown in Preparation Example 2 as a catalyst. To the reactor, 5.0 g of KF / Al ₂ O ₃ and 20 g of methanol were added, cooled in a dry ice-acetone bath, deaerated inside the reactor, and then 2.8 g of TFE was introduced from the gas inlet. When the reaction temperature was set to 80 ° C., the pressure was 0.45 MPa. Since the pressure reached 0.20 MPa 6 hours after the start of the reaction, the reactor was placed in an ice bath and cooled, and the contents were taken out. The recovered organic matter was 21.0 g (recovery rate 92.1%).

  As a result of analyzing the collected organic matter by gas chromatography, the yield of HFE-254pc based on TFE was 61.2%.

Example 3
The reaction was carried out in the same manner as in Example 1 using KF / Al ₂ O ₃ shown in Preparation Example 1 as a catalyst. To the reactor, 2.5 g of KF / Al ₂ O ₃ and 10 g of methanol were added, cooled in a dry ice-acetone bath and deaerated inside the reactor, and then 1.4 g of TFE was introduced from the gas inlet. When the reaction temperature was set to 50 ° C., the pressure was 0.21 MPa. Since the pressure became 0.10 MPa 4 hours after the start of the reaction, the reactor was placed in an ice bath and cooled, and 1.4 g of TFE was further introduced into the reactor to continue the reaction. At a reaction temperature of 50 ° C., the pressure became 0.32 MPa. Since the pressure became 0.20 MPa 3 hours after the reaction was resumed, the reactor was placed in an ice bath and cooled, and the contents were taken out. The recovered organic matter was 11.3 g (recovery rate 88.3%).

  As a result of analyzing the collected organic matter by gas chromatography, the HFE-254pc yield based on TFE was 52.5%.

[Comparative Example 1]
The reaction was performed in the same manner as in Example 1 using Al ₂ O ₃ as a catalyst.

To the reactor, 5.0 g of Al ₂ O ₃ and 20 g of methanol were added, cooled in a dry ice-acetone bath and deaerated inside the reactor, and then 2.8 g of TFE was introduced from the gas inlet. When the reaction temperature was set to 80 ° C., the pressure was 0.45 MPa. Even after 3 hours from the start of the reaction, the pressure was 0.45 MPa. The reactor was placed in an ice bath and cooled, and the contents were taken out. As a result, the recovered organic matter was 18.4 g (recovery rate: 80.7%).

  As a result of analyzing the collected organic substances by gas chromatography, the yield of HFE-254pc based on TFE was 0%.

[Comparative Example 2]
The reaction was conducted in the same manner as in Example 1 using KF as the catalyst.

  The reactor was charged with 2.5 g of KF and 10 g of methanol, cooled in a dry ice-acetone bath and deaerated inside the reactor, and then 2.5 g of TFE was introduced from the gas inlet. When the reaction temperature was set to 80 ° C., the pressure was 0.46 MPa. After 7 hours from the start of the reaction, the pressure was 0.37 MPa. The reactor was placed in an ice bath and cooled, and the contents were taken out. The recovered organic matter was 9.5 g (recovery rate 76.0%).

  As a result of analyzing the collected organic matter by gas chromatography, the yield of HFE-254pc based on TFE was 18.2%.

Example 4
The method of Catalyst Preparation Example 1 was repeated twice to prepare KF / Al ₂ O ₃ having a potassium fluoride loading of 47 wt%. 100 ml of 47 wt% KF / Al ₂ O ₃ was filled in a SUS304 reaction tube (21 mmφ × 300 mm), and the reaction tube was heated to 80 ° C. in an electric furnace. Through a vaporizer heated to 80 ° C., TFE and methanol were introduced into the reactor under normal pressure with a contact time of 80 seconds and TFE / methanol (molar ratio 1/10). The reaction product was collected by installing an ice water bath trap and a dry ice-acetone bath trap at the reactor outlet. The reaction was continued for 30 hours or more, and the collected organic matter was analyzed by gas chromatography. The HFE-254pc yield and recovery after 25-30 hours were 88.5% and 93.6%, respectively, based on TFE.

Example 5
The same method as in Catalyst Preparation Example 2 was repeated twice except that NKHO-24 (manufactured by Sumika Alchem Chemical Co., Ltd .: particle size 2 to 4 mm, specific surface area 160 m ² / g) was used instead of activated alumina NKH3-24. KOH / Al ₂ O ₃ having a potassium loading of 32 wt% was prepared. 100 ml of 32 wt% KOH / Al ₂ O ₃ was charged into a SUS304 reaction tube (21 mmφ × 300 mm), and the reaction tube was heated to 80 ° C. in an electric furnace. Through a vaporizer heated to 80 ° C., TFE and methanol were introduced into the reactor under normal pressure with a contact time of 40 seconds and TFE / methanol (molar ratio 1/5). The reaction product was collected by installing an ice water bath trap and a dry ice-acetone bath trap at the reactor outlet. The reaction was continued for 10 hours or longer, and the collected organic matter was analyzed by gas chromatography. The HFE-254pc yield and recovery after 5-11 hours were 78.3% and 94.6%, respectively, based on TFE.

Claims (4)

A method for producing a fluorinated ether, comprising reacting a fluorinated olefin having 2 or more carbon atoms containing at least one fluorine atom and an alcohol having 1 or more carbon atoms in the presence of a solid catalyst. The method for producing a fluorinated ether according to claim 1, wherein the solid catalyst is a catalyst in which an alkali metal or an alkaline earth metal compound is supported on activated alumina. The solid catalyst is potassium fluoride / activated alumina, potassium hydroxide / activated alumina or sodium hydroxide / activated alumina in which activated fluoride is loaded with potassium fluoride, potassium hydroxide or sodium hydroxide. A method for producing a fluorinated ether according to claim 1 or 2. 4. The production method according to claim 1, wherein the fluorinated olefin is tetrafluoroethylene, the alcohol is methanol, and the fluorinated ether is 1-methoxy-1,1,2,2-tetrafluoroethane.