METHOD FOR PURIFYING A PHOSPHORUS-CONTAINING OLEFIN COMPOUND SALT AND METHOD FOR PRODUCING AN OLEFIN COMPOUND USING THIS RECOVERED PURIFIED PRODUCT

Description

Technical Field

[0001] The present invention relates to a method for purifying a phosphorus-containing olefin compound salt and a method for producing an olefin compound using a purified product obtained thereby.Background Art

[0002] (E)-1,2-difluoroethylene (hereinafter referred to as "R1132(E)") has a low global warming potential (GWP), and thus has attracted attention as an alternative refrigerant to difluoromethane (R-32) and 1,1,1,2,2-pentafluoroethane (R-125), which are greenhouse gases.

[0003] Conventionally, as a method for producing R1132(E), for example, H.-J. Frohn et al, J. Fluorine Chem., 123, 43-49 (2003) has reported that a reaction product containing a target product can be obtained according to the following procedure (Abstract and "3.2. Reactions of olefin 1 with Pbu3," in particular, 3.2.2) .

[0004] The above report example states that in addition to the target product R1132(E), about 16% (0.3 g for 1.9 g) of cis- and trans-1H-nonafluoro-2-propoxyethene (cis:trans = 1:5) was also present as an impurity.

[0005] R. Blachnik et al., Zeitschrift für Kristallographie - New Crystal Structures, 216(1-4), 219-220 (2001) report on the crystal structure of [Ph 3 P-CH=CH-PPh 3 ][BF 4 ] 2 , using single crystals obtained by reacting starting materials in dry ethanolic solution to produce the target compound, filtrating the reaction solution and slowly evaporating the solvent, so that single crystals of the target compound precipitated from the solution.

[0006] H. Wessolowski et al., J. Fluorine Chem., 80(2), 149-152 (1996) describes the synthesis of perfluoroalkenyl phosphonates and iodoperfluoroalkenes from CF 3 -C(CF 3 ) 2 -CF=CF 2 and (n-F 9 C 4 )O-CF=CF 2 .Summary of InventionTechnical Problem

[0007] The present invention was made in view of the above problems, and an object of the present invention is to provide a method for purifying a phosphorus-containing olefin compound salt as a raw material or an intermediate that is useful to increase the purity of a target product in a method for producing an olefin compound and that can be applied to the production method, and to also provide a method for producing an olefin compound using a purified product obtained thereby.Solution to Problem

[0008] The present invention thus provides a method for purifying a phosphorus-containing olefin compound salt (also referred to as "the present purification method" hereinafter), comprising reprecipitating and / or recrystallizing a solid comprising at least one phosphorus-containing olefin compound salt of formula (1) or (2): wherein X 1 , X 2 each independently are H,F, Cl, Br or I; Y is H, F, Cl, Br, I, alkyl, alkyl ether, fluoroalkyl or fluoroalkyl ether; W +< each independently is a monovalent cation comprising PR 3 or P(OR) 3 , wherein R each independently are groups having a saturated or unsaturated structure containing C and H, are optionally bonded together to form a ring, and optionally contain an atom other than C and H; and M -< is a boron fluoride anion; in a solvent, thereby obtaining a purified product of the phosphorus-containing olefin compound salt, wherein after the solid is dissolved in a solvent at 45-60°C, the temperature of a solution is reduced at -0.25°C / min or less to thereby perform reprecipitation and / or recrystallization.

[0009] Also, the present invention provides a method for producing an olefin compound (also referred to as "the present production method" hereinafter), comprising (i) purifying a phosphorus-containing olefin compound salt by performing the method defined above, and (ii) reacting the obtained purified product and a base to thereby obtain a reaction product containing a dephosphorized and hydrogenated olefin compound.

[0010] Preferred embodiments of the invention are as defined in the appended dependent claims and / or in the following detailed description.Advantageous Effects of Invention

[0011] According to the present purification method, a solid containing the salt is reprecipitated and / or recrystallized in a solvent, thereby obtaining a highly purified product of the phosphorus-containing olefin compound salt. The purified product of the phosphorus-containing olefin compound salt is useful as a raw material or an intermediate in a method for producing an olefin compound. An olefin compound with high purity can be produced by synthesizing the target product using the purified product as a raw material or an intermediate.Description of Embodiments

[0012] The present purification method comprises reprecipitating and / or recrystallizing a solid comprising at least one phosphorus-containing olefin compound salt of formula (1) or (2): wherein X 1 , X 2 each independently are H,F, Cl, Br or I; Y is H, F, Cl, Br, I, alkyl, alkyl ether, fluoroalkyl or fluoroalkyl ether; W +< each independently is a monovalent cation comprising PR 3 or P(OR) 3 , wherein R each independently are groups having a saturated or unsaturated structure containing C and H, are optionally bonded together to form a ring, and optionally contain an atom other than C and H; and M -< is a boron fluoride anion; in a solvent, thereby obtaining a purified product of the phosphorus-containing olefin compound salt, wherein after the solid is dissolved in a solvent at 45-60°C, the temperature of a solution is reduced at -0.25°C / min or less to thereby perform reprecipitation and / or recrystallization.

[0013] According to the present purification method, which has the above feature, a solid containing the salt is reprecipitated and / or recrystallized in a solvent, thereby obtaining a highly purified product of the phosphorus-containing olefin compound salt. Such a purified product of the phosphorus-containing olefin compound salt is useful as a raw material or an intermediate in a method for producing an olefin compound. An olefin compound with high purity can be produced by synthesizing the target product using the purified product as a raw material or an intermediate.

[0014] The phosphorus-containing olefin compound salt A is of the formula (1): wherein X 1 , X 2 each independently are H,F, Cl, Br or I; W +< each independently is a monovalent cation comprising PR 3 or P(OR) 3 , wherein R each independently are groups having a saturated or unsaturated structure containing C and H, are optionally bonded together to form a ring, and optionally contain an atom other than C and H; and M -< is a boron fluoride anion.

[0015] X 1 and X 2 are each independently F, Cl, Br, I, or H. Of these, when the purified product is used as a raw material or an intermediate in a method for producing an olefin compound, and when the target olefin compound is R1132(E), X 1 and X 2 are both preferably F.

[0016] W +< s are the same or different and each is a monovalent cation comprising PR 3 or POR 3 , provided that Rs are groups having a saturated or unsaturated structure containing C and H, are optionally bonded together to form a ring, and optionally contain an atom other than C and H. That is, W +< s are cations of organic phosphine compounds.

[0017] Rs are groups having a saturated or unsaturated structure containing C and H, are optionally bonded together to form a ring, and optionally contain an atom other than C and H. Examples of a hydrocarbon group, which is a kind of the skeleton of this group, include alkyl, alkenyl, alkynyl, aryl, arylalkyl, and arylalkenyl, as well as hydrocarbon groups having a double or triple bond that satisfy the above requirements. These hydrocarbon groups may be bonded together to form a ring, and may have a substituent containing an atom other than C and H.

[0018] The number of carbon atoms in the above alkyl, alkenyl, and alkynyl (hereinafter collectively referred to as the "alkyl etc.") is not limited. The number of carbon atoms in the alkyl group is preferably 1-10, more preferably 1-8, even more preferably 1-6, and most preferably 1-4. Further, the number of carbon atoms in the alkenyl and alkynyl group is preferably 2-10, more preferably 2-8, even more preferably 2-6, and most preferably 2-4. When the alkyl etc. have a cyclic structure, the number of carbon atoms is preferably 4-12, more preferably 4-10, even more preferably 5-8, and most preferably 6-8.

[0019] The structure of the alkyl etc. is not limited as long as the above requirements of Rs are satisfied. The alkyl etc. may be linear or may have a side chain. The alkyl etc. may have a chain structure or a cyclic structure (cycloalkyl, cycloalkenyl, or cycloalkynyl). The alkyl etc. may also have one or two or more substituents containing an atom other than C and H. In addition to such substituents, the alkyl etc. may contain one or two or more atoms other than C and H in the chain structure or the cyclic structure. Examples of atoms other than C and H include one or two more of O, N, and S.

[0020] Examples of the alkyl include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, and 2-ethylhexyl groups. Examples of the cycloalkyl group include cyclopentyl, cyclohexyl, cycloheptyl, and 2-methylcyclohexyl groups. Examples of the alkenyl include vinyl, allyl, and isopropenyl groups. Examples of the cycloalkenyl include a cyclohexenyl group.

[0021] The number of carbon atoms in the above aryl, arylalkyl, and arylalkenyl (hereinafter collectively referred to as the "aryl etc.") is not limited. The number of carbon atoms is preferably 6-15, more preferably 6-12, and even more preferably 6-10.

[0022] The structure of the aryl etc. is not limited as long as the above requirements of Rs are satisfied. The aryl etc. may have one or two or more substituents. For example, the aromatic ring contained in the aryl etc. may have one or two or more substituents. The position of the substituents may be any of o-, m-, and p-. Examples of the substituents include one or two or more of halogen atoms (e.g., F, Cl and Br), alkyl, alkenyl, nitro, amino, hydroxyl, and alkoxy. When such a substituent is located on the aromatic ring, the position of the substituent may be any of o-, m-, and p-.

[0023] Examples of the aryl include phenyl, tolyl, ethylphenyl, xylyl, cumenyl, mesityl, methoxyphenyl (o-, m-, and p-), ethoxyphenyl (o-, m-, and p-), 1-naphthyl, 2-naphthyl, and biphenylyl. Examples of the arylalkyl include benzyl, methoxybenzyl (o-, m-, and p-), ethoxybenzyl (o-, m-, and p-), and phenethyl. Examples of the arylalkenyl include styryl and cinnamyl.

[0024] Three Rs included in PR 3 and POR 3 may be bonded together to form a ring. The structure of the ring is not limited. For example, the number of ring members can generally be 4-10, and preferably 5-8, including a phosphorus atom. The number of ring members is generally 5 or 6. The ring may contain heteroatoms (e.g., O, N and S) in its structure. Further, the ring may have other substituents. The ring may also have an unsaturated bond in its structure.

[0025] Three Rs included in PR 3 and POR 3 may have the same or different structures.

[0026] M -< is a boron fluoride anion.

[0027] The phosphorus-containing olefin compound salt B is of the formula (2): wherein X 1 , X 2 and W +< are as defined above, and Y is F, Cl, Br, I, H, alkyl, alkyl ether, fluoroalkyl or fluoroalkyl ether.

[0028] The explanations of X 1 , X 2 , W +< , and M -< are the same as those for the phosphorus-containing olefin compound salt A.

[0029] Y is F, Cl, Br, I, H, alkyl, alkyl ether, fluoroalkyl or fluoroalkyl ether.

[0030] The explanation of alkyl is the same as that of Rs (alkyl) in the phosphorus-containing olefin compound salt A.

[0031] Examples of alkyl ether include compounds with oxygen atoms bonded to Rs (alkyl) in the phosphorus-containing olefin compound salt A.

[0032] Examples of fluoroalkyl include compounds with fluorine atoms substituted on carbon atoms in any number and in any combination. Of these, preferred are C 1-4 compounds, and particularly preferred are C 1 compounds.

[0033] Examples of fluoroalkyl ether include compounds with an oxygen atom bonded to the fluoroalkyl group.

[0034] The present purification method comprises reprecipitating and / or recrystallizing a solid containing at least one of the salts A and B in a solvent, thereby obtaining a purified product of the phosphorus-containing olefin compound salt. A part or whole of the phosphorus-containing olefin compound salt may be a crystal. In the present disclosure, the salt may partially contain non-crystalline portions and that the salt contains impurities, the whole, including the salt and impurities, is described as a "solid." Further, in identifying the purification method, the method is described as "reprecipitation and / or recrystallization" so that the method is not limited to recrystallization alone for the above reason.

[0035] The solid containing at least one of the salts A and B is not limited. When the solid is applied to a method for producing an olefin compound by reacting the purified product with a base to perform dephosphorization and hydrogenation, thereby obtaining an olefin compound, the solid preferably contains a phosphorus-containing olefin compound salt as a production raw material or intermediate of the target olefin compound.

[0036] For example, in the production process of R1132(E) as shown below: the phosphorus-containing olefin compound salt to be reacted with the base is one of the specific examples of the present salt A. For example, in the production process of R1132(E), the solid containing a phosphorus-containing olefin compound salt contains at least one compound (impurity) selected from: (trans-2-perfluoropropoxy-1,2-difluoroethen-1-yl)(tributyl) phosphonium tetrafluoroboranuide, [trans-C 3 F 7 OCF=CFPBu 3 ][BF 4 ], (cis-2-perfluoropropoxy-1,2-difluoroethen-1-yl)(tributyl) phosphonium tetrafluoroboranuide, [cis-C 3 F 7 OCF=CFPBu 3 ][BF 4 ], perfluoropropoxy vinyl ether (C 3 VE), (2,2,3,3,3-pentafluoro-1-tributylphosphin-1-one) tetrafluoroboranuide ([CF 3 CF 2 C(O)-PBu 3 ][BF 4 ]), boron trifluoride tributylphosphine oxide (BF 3 ·O=PBu 3 ), tetrafluoroboric acid (HBF 4 ), (1,2-difluoroethen-1-yl)(tributyl) phosphonium tetrafluoroboranuide)([CHF=CFPBu 3 ][BF 4 ]), diethyl ether (Et 2 O), dimethyl ether (Mt 2 O), and 2-methoxy-2-methylpropane (MTBE).

[0037] Although the conditions for reprecipitation and / or recrystallization are not limited, the solvent is preferably, for example, at least one member selected from ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, methanol, ethanol, propanol, isopropanol, and butanol. Of these, ethyl acetate is more preferred in terms of the solubility of the solid and the cost of the solvent. The pH during reprecipitation and / or recrystallization is preferably 8 or less. By setting the pH in such a range, hydrolysis of the phosphorus-containing olefin compound salt can be prevented, and reprecipitation and / or recrystallization can be performed. The number of times of reprecipitation and / or recrystallization is not limited; however, in the present purification method, in particular, when the following suitable conditions are used, it is possible to obtain a purified product with high purity (≥ 95 mass%) by one treatment.

[0038] The temperature at which the solid is dissolved in a solvent at 45-60°C, and the temperature of the solution after that is reduced at -0.25°C / min or less to perform reprecipitation and / or recrystallization. It is preferable that after dissolution in a solvent at 45-50°C, the temperature of the solution is reduced at -0.25°C / min or less to perform reprecipitation and / or recrystallization. -0.20°C / min or less is preferred, and - 0.15°C / min or less is more preferred. In terms of obtaining a purified product with high purity, it is preferable to slowly reduce the temperature of the solution as described above.

[0039] The method for extracting the purified product is not limited. For example, it is preferable that the present purification method further has a step of extracting the purified product by suction filtration and / or pressure filtration. In doing so, it is more preferable that the temperature of the mixture containing the purified product is ≤ 5°C.

[0040] According to the present purification method, at least some of the impurities are removed by reprecipitation and / or recrystallization. Therefore, the purity of the phosphorus-containing olefin compound salt in the purified product is preferably ≥ 95 mass%, and more preferably ≥ 99 mass%.

[0041] The purified product (phosphorus-containing olefin compound salt) with impurities that are reduced in this way can be applied to, for example, a method for producing an olefin compound by reacting the purified product with a base to perform dephosphorization and hydrogenation, thereby obtaining an olefin compound. In this case, since the purity of the phosphorus-containing olefin compound salt is improved in the purified product, the target olefin compound can be synthesized with high purity. In particular, the phosphorus-containing olefin compound salt in the production method of R1132(E) disclosed in H.-J. Frohn et al, J. Fluorine Chem., 123, 43-49 (2003) discussed above is not purified as in the present invention. Together with R1132(E), which is the target compound, low-boiling-point components, such as 1,1,2-trifluoroethylene, pentafluoroethane (R-125), R-134a, and (Z)-1,2-difluoroethylene (R1132(Z)), which are difficult to separate by distillation, are produced as by-products; however, the production of these low-boiling-point components as by-products can be suppressed by using the purified product after the present purification method to produce an olefin compound. In this respect, the present invention is more highly useful than the prior art.

[0042] That is, the present invention includes the present production method, comprising reacting a purified product of at least one phosphorus-containing olefin compound salt selected from the phosphorus-containing olefin compound salts A and B obtained by the present purification method with a base to obtain a reaction product containing a dephosphorized and hydrogenated olefin compound. In the present invention, the target olefin compound is preferably, for example, (E)-1,2-difluoroethylene (R1132(E)).

[0043] The reaction product in the present production method contains (E)-1,2-difluoroethylene and, for example, at least one member selected from acetylene, trifluoroethylene, pentafluoroethane (R-125), 1,1,1,2-tetrafluoroethane (R-134a), (Z)-1,2-difluoroethylene, tetrafluoroethylene, and cis- and trans-1H-nonafluoro-2-propoxyethene.Examples

[0044] Embodiments of the present disclosure are described in more detail below based on Examples.Example 1 (Ex-1)

[0045] A target olefin compound (C) (R1132(E)) was synthesized from a raw material olefin (A) (C 3 F 7 OCF=CF 2 ) according to the following formula:

[0046] Specifically, PBu 3 (89.2 g, 440 mmol) was dissolved in ether (500 ml) at 5°C. While stirring this solution, the raw material olefin (A) (39.2 g, 147 mmol) was added dropwise at a temperature of 5°C over 20 minutes to cause reaction.

[0047] After the reaction mixture was maintained at 5°C for 2 hours, BF 3 OEt 2 (63.3 g, 446 mmol) was added at a temperature of 5-20°C, and the mixture was then stirred at a temperature of 25°C for 1.5 hours.

[0048] The upper ether layer was decanted, and the residue was washed with ether and dried in vacuum, thereby obtaining a white sticky substance (a solid containing the phosphorus-containing olefin compound salt (B)) (155.5 g). When the solid was analyzed by NMR, 16 mass% of [CF 3 CF 2 C(O)-PBu 3 ][BF 4 ]was contained as an impurity.

[0049] The solid containing the phosphorus-containing olefin compound salt (B) was dissolved in ethyl acetate at 50°C, and the temperature of the solution was reduced at -0.25 °C / min to perform reprecipitation and / or recrystallization, thereby obtaining a purified product. The purified product was extracted by suction filtration.

[0050] A 50 mass% aqueous sodium hydroxide solution was added to the purified product to react with a base. The liquid temperature was raised from 28°C to 50°C.

[0051] The reaction product (distillate) with the base was analyzed by gas chromatogram. The results are shown in Table 1 below.Comparative Example 1 (CE-1)

[0052] A target olefin compound (C) (R1132(E)) was synthesized from a raw material olefin (A) (C 3 F 7 OCF=CF 2 ) under the same conditions as in Example 1, except that the solid containing the phosphorus-containing olefin compound salt (B) was not reprecipitated and recrystallized. That is, a white sticky substance (a solid containing the phosphorus-containing olefin compound salt (B)) was directly reacted with a base. The results are shown in Table 1 below. Table 1GC analysis results of reaction product (distillate) with base (GC%)HC=CHCF 2 =CFH1132(E)R-1251132(Z)R-134aC 3 H 7 OCF=CFHTotalcis-cis-CE-11.0418.9582.9110.6041.6651.2780.2250.32296.996Ex-10.1670.68998.6110.02n.d.0.256n.d.n.d.99.743

[0053] As is clear from the results of Table 1, in the case of Example 1, in which the phosphorus-containing olefin compound salt (B) was purified by reprecipitation and / or recrystallization, the yield of the target olefin compound (C) (R1132(E)) was higher, and the content of isomers and other by-products was relatively lower, compared with Comparative Example 1, in which reprecipitation and / or recrystallization was not performed.

Claims

1. A method for purifying a phosphorus-containing olefin compound salt, comprising reprecipitating and / or recrystallizing a solid comprising at least one phosphorus-containing olefin compound salt of formula (1) or (2): wherein X1, X2 each independently are H,F, Cl, Br or I; Y is H, F, Cl, Br, I, alkyl, alkyl ether, fluoroalkyl or fluoroalkyl ether wherein the alkyl is linear or has a side chain or is cyclic and may also have one or two or more substituents containing an atom other than C and H and / or may contain one or two or more atoms other than C and H in the chain structure or the cyclic structure; W+ each independently is a monovalent cation comprising PR3 or P(OR)3, wherein R each independently are groups having a saturated or unsaturated structure containing C and H, are optionally bonded together to form a ring, and optionally contain an atom other than C and H; and M- is a boron fluoride anion; in a solvent, thereby obtaining a purified product of the phosphorus-containing olefin compound salt, wherein after the solid is dissolved in a solvent at 45-60°C, the temperature of a solution is reduced at -0.25°C / min or less to thereby perform reprecipitation and / or recrystallization.

2. The method of claim 1, wherein the solvent is at least one of ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, methanol, ethanol, propanol, isopropanol, and butanol.

3. The method of claim 1 or 2, further comprising extracting the purified product by suction filtration and / or pressure filtration.

4. The method of any of claims 1-3, wherein the solid comprises at least one compound selected from (trans-2-perfluoropropoxy-1,2-difluoroethen-1-yl) (tributyl) phosphonium tetrafluoroboranuide, (cis-2-perfluoropropoxy-1,2-difluoroethen-1-yl) (tributyl) phosphonium tetrafluoroboranuide, perfluoropropoxy vinyl ether, (2,2,3,3,3-pentafluoro-1-tributylphosphin-1-one) tetrafluoroboranuide, boron trifluoride tributylphosphine oxide, tetrafluoroboric acid, (1,2-difluoroethen-1-yl) (tributyl) phosphonium tetrafluoroboranuide), diethyl ether, dimethyl ether, and 2-methoxy-2-methylpropane.

5. The method of any of claims 1-4, wherein the purity of the phosphorus-containing olefin compound salt in the purified product is ≥ 95 mass%.

6. A method for producing an olefin compound, comprising (i) purifying a phosphorus-containing olefin compound salt by performing the method of any of claims 1-5, and (ii) reacting the obtained purified product and a base to thereby obtain a reaction product containing a dephosphorized and hydrogenated olefin compound.

7. The method of claim 6, wherein the olefin compound is (E)-1,2-difluoroethylene.

8. The method of claim 6 or 7, wherein the reaction product comprises (E)-1,2-difluoroethylene and at least one of acetylene, trifluoroethylene, pentafluoroethane (R-125), 1,1,1,2-tetrafluoroethane (R-134a), (Z)-1,2-difluoroethylene, tetrafluoroethylene, and cis- and trans-1H-nonafluoro-2-propoxyethene.