Method for producing (HYDRO)halocarbon

Abstract

To provide a method for obtaining a high-purity (hydro)halocarbon from an azeotropic or azeotropic-like composition comprising a (hydro)halocarbon and a compound different from the (hydro)halocarbon.SOLUTION: A method for producing a (hydro)halocarbon according to one embodiment includes a step of purifying the (hydro)halocarbon by reduced-pressure distillation of an azeotropic or azeotropic-like composition comprising the (hydro)halocarbon and a compound different from the (hydro)halocarbon. A method for producing a (hydro)halocarbon according to another embodiment includes a step of purifying the (hydro)halocarbon by reduced-pressure distillation of an azeotropic or azeotropic-like composition comprising the (hydro)halocarbon and a compound different from the (hydro)halocarbon, wherein standard boiling points of both the (hydro)halocarbon and the compound are 80°C or lower.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing (hydro)halocarbons.

Background Art

[0002] Unsaturated chlorofluorocarbons having a double bond in the molecule, such as 1-chloro-3,3,3-trifluoropropene (hereinafter also referred to as HCFO-1233zd, 1233zd), have a low boiling point and a very short atmospheric lifetime, so they have both a low ozone depletion potential and a low global warming potential. Therefore, unsaturated chlorofluorocarbons such as HCFO-1233zd are expected as one of the compounds that can be used as cleaning agents, refrigerants, etc.

[0003] For example, Z-1-chloro-3,3,3-trifluoropropene (hereinafter also referred to as HCFO-1233zd(Z), 1233zd(Z)), which is one of the unsaturated chlorofluorocarbons, can be produced by fluorinating 1,1,1,3,3-pentachloropropane (hereinafter also referred to as HCC-240fa, 240fa) with hydrogen fluoride. In the fluorination of HCC-240fa, a reaction product containing, together with HCFO-1233zd(Z), geometric isomers such as E-1-chloro-3,3,3-trifluoropropene (hereinafter also referred to as HCFO-1233zd(E), 1233zd(E)), by-products such as 3-chloro-1,1,1,3-tetrafluoropropane (hereinafter also referred to as HCFC-244fa, 244fa), 2-chloro-1,1,1,3,3-pentafluoropropane (hereinafter also referred to as HCFC-235da, 235da), and unreacted hydrogen fluoride is obtained (Patent Document 1). Since HCFC-244fa and HCFC-235da form an azeotropic-like composition with the target substance HCFO-1233zd(Z), it is difficult to purify high-purity HCFO-1233zd(Z) from the reaction product.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One of the problems of the present invention is to provide a method for obtaining a highly pure (hydro)halocarbon from an azeotropic or azeotrope-like composition containing a (hydro)halocarbon and a compound different from the (hydro)halocarbon.

Means for Solving the Problems

[0006] According to one embodiment of the present invention, there is provided a method for producing a (hydro)halocarbon, comprising a step of subjecting an azeotropic or azeotrope-like composition containing a (hydro)halocarbon and a compound different from the (hydro)halocarbon to vacuum distillation to purify the (hydro)halocarbon.

[0007] In the vacuum distillation, the top pressure of the distillation column may be 50 kPa or less.

[0008] In the vacuum distillation, the top temperature of the distillation column may be 20°C or less.

[0009] The standard boiling points of the (hydro)halocarbon and the compound may both be 120°C or less.

[0010] The standard boiling points of the (hydro)halocarbon and the compound may both be 80°C or less.

[0011] The (hydro)halocarbon is a compound represented by the general formula (1) C m H a F b Cl c (where m is an integer of 2 to 5, a, b, and c are integers of 0 or more, b + c ≧ 1 is satisfied, and a + b + c = 2m - 2, 2m, or 2m + 2 is satisfied), The compound may be at least one selected from hydrogen fluoride and the compound represented by the general formula (1) (excluding the compound selected as the (hydro)halocarbon).

[0012] The (hydro)halocarbon is a compound represented by the general formula (2) C n H d FeCl f O g (where n is an integer of any one of 3 to 5, d, e, and f are integers of 0 or more, g is an integer of 1 or more, and e + f ≧ 1 is satisfied, and d + e + f = 2n - 2, 2n, or 2n + 2 is satisfied). The compound may be at least one selected from hydrogen fluoride and the compound represented by the general formula (2) (excluding the compound selected as the (hydro)halocarbon).

[0013] The (hydro)halocarbon is cis-1-chloro-3,3,3-trifluoropropene, and the compound may be 3-chloro-1,1,1,3-tetrafluoropropane.

[0014] The (hydro)halocarbon is cis-1,2-dichloro-3,3,3-trifluoropropene, and the compound may be 1,1-dichloro-3,3,3-trifluoropropene.

[0015] The (hydro)halocarbon is cis-1,2-dichloro-3,3-difluoropropene, and the compound may be trans-1,2-dichloro-3,3-difluoropropene.

[0016] According to another embodiment of the present invention, there is provided a method for producing a (hydro)halocarbon, including a step of subjecting an azeotropic or azeotrope-like composition containing at least one (hydro)halocarbon and a compound different from the (hydro)halocarbon to vacuum distillation to purify the (hydro)halocarbon, wherein the standard boiling points of the (hydro)halocarbon and the compound are both 80°C or lower.

[0017] According to another embodiment of the present invention, azeotropic or azeotrope-like composition containing cis-1-chloro-3,3,3-trifluoropropene and a saturated hydrochlorofluorocarbon containing at least 3-chloro-1,1,1,3-tetrafluoropropane is subjected to vacuum distillation to recover a fraction containing cis-1-chloro-3,3,3-trifluoropropene as a main component, a step of contacting the fraction with a base to purify cis-1-chloro-3,3,3-trifluoropropene, and a step of further subjecting the fraction to vacuum distillation to obtain high-purity cis-1-chloro-3,3,3-trifluoropropene having a 3-chloro-1,1,1,3-tetrafluoropropane content of 3% by mass or less, and a method for producing high-purity cis-1-chloro-3,3,3-trifluoropropene is provided.

[0018] After the step of recovering the fraction and before the step of obtaining cis-1-chloro-3,3,3-trifluoropropene, the method may further include a step of contacting the fraction with a base to purify cis-1-chloro-3,3,3-trifluoropropene.

[0019] The step of purifying the 1-chloro-3,3,3-trifluoropropene may be a step of dehydrohalogenating 3-chloro-1,1,1,3-tetrafluoropropane contained in the fraction.

Effect of the Invention

[0020] According to one embodiment of the present invention, a highly pure (hydro)halocarbon can be obtained from an azeotropic or azeotrope-like composition containing a (hydro)halocarbon and a compound different from the (hydro)halocarbon.

Mode for Carrying Out the Invention

[0021] Hereinafter, each embodiment of the present invention will be described. However, the present invention can be implemented in various forms without departing from the gist thereof, and should not be construed as being limited to the description content of the embodiments exemplified below. Further, even if there are other effects different from the effects brought about by the aspects of the following embodiments, those that are obvious from the description in this specification or can be easily predicted by those skilled in the art are naturally considered to be brought about by the present invention.

[0022] [Azeotropic-like composition] An azeotropic composition is characterized in that the boiling point of a liquid composition is fixed under a predetermined pressure, and the composition of the vapor (gas phase) of the liquid composition during boiling is the same as the composition of the liquid composition (liquid phase) during boiling. That is, in an azeotropic composition, fractional distillation of the components of the liquid composition does not occur when the liquid composition boils. On the other hand, an azeotropic-like composition refers to a composition having the same behavior as an azeotropic composition, in which the boiling point of the liquid composition is substantially fixed under a predetermined pressure, and when the liquid composition volatilizes, it volatilizes with a composition substantially the same as the composition of the liquid. Therefore, the composition of the vapor (gas phase) of the liquid composition during boiling changes only to an extent that can be ignored with respect to the composition of the liquid composition (liquid phase) during boiling. That is, in an azeotropic-like composition, fractional distillation of the components of the liquid composition hardly occurs during boiling. On the other hand, a non-azeotropic composition that is not azeotropic-like is characterized in that the composition of the gas phase of the composition and the composition of the liquid phase of the composition change during evaporation or condensation.

[0023] Hereinafter, a method for producing a (hydro)halocarbon according to the present embodiment (hereinafter referred to as the present production method) will be described. In the present production method, a (hydro)halocarbon can be selectively produced from an azeotropic or azeotropic-like composition containing a (hydro)halocarbon and impurities.

[0024] A (hydro)halocarbon is a compound containing at least a carbon atom and a halogen atom in the molecule. The (hydro)halocarbon may further contain a hydrogen atom and / or an oxygen atom. In one embodiment, the (hydro)halocarbon has the general formula (1): C m H a Fb Cl c is a compound represented by the general formula (1). In the general formula (1), m is any integer from 2 to 5, a, b, and c are integers of 0 or more, b + c ≥ 1 is satisfied, and a + b + c = 2m - 2, 2m, or 2m + 2 is satisfied. The compound represented by the general formula (1) can be produced, for example, by halogenating (e.g., fluorinating, chlorinating) a saturated hydrocarbon compound or an unsaturated hydrocarbon compound that is industrially produced, or by dehydrohalogenating (e.g., dehydrofluorinating, dehydrochlorinating) a halogenated saturated hydrocarbon compound or a halogenated unsaturated hydrocarbon compound that is industrially produced. Further, in another embodiment, the (hydro)halocarbon has the general formula (2): C n H d F e Cl f O g is a compound represented by the general formula (2). In the general formula (2), n is any integer from 3 to 5, d, e, and f are integers of 0 or more, g is an integer of 1 or more, e + f ≥ 1 is satisfied, and d + e + f = 2n - 2, 2n, or 2n + 2 is satisfied. The compound represented by the general formula (2) can be produced, for example, by hydroxylation of a halogenated saturated hydrocarbon compound or a halogenated unsaturated hydrocarbon compound that is industrially produced, or by alkylation of an industrially produced halogenated saturated / unsaturated ether.

[0025] In these reactions, by-products may be generated together with the (hydro)halocarbon. When the by-product forms an azeotropic or azeotrope-like composition with the target (hydro)halocarbon, the purity of the target (hydro)halocarbon will decrease. Also, in these reactions, unreacted raw materials (e.g., hydrogen fluoride used in halogenation) may remain. This remaining hydrogen fluoride is also one of the factors that lower the purity of the target (hydro)halocarbon.

[0026] The inventor of the present invention has completed the present invention by obtaining the knowledge that a high-purity (hydro)halocarbon, which is the target substance, can be obtained by subjecting an azeotropic or azeotrope-like composition containing the (hydro)halocarbon as the target substance and a compound different from the (hydro)halocarbon to vacuum distillation.

[0027] Hereinafter, a production method according to an embodiment of the present invention (hereinafter referred to as "this production method") will be described. This production method includes a step of purifying a (hydro)halocarbon, which is the target substance, by subjecting an azeotropic or azeotrope-like composition containing the (hydro)halocarbon as the target substance and a compound different from the (hydro)halocarbon to vacuum distillation. Here, the compound different from the (hydro)halocarbon is a compound that is not the same as the (hydro)halocarbon as the target substance and contains at least a carbon atom and a halogen atom in the molecule. The compound different from the (hydro)halocarbon may further contain a hydrogen atom in the molecule in addition to the carbon atom and the halogen atom. The compound different from the (hydro)halocarbon may be at least one selected from hydrogen fluoride and the compound represented by the above general formula (1) (excluding the compound selected as the (hydro)halocarbon). Further, the compound different from the (hydro)halocarbon may be at least one selected from hydrogen fluoride and the compound represented by the above general formula (2) (excluding the compound selected as the (hydro)halocarbon).

[0028] [First Embodiment] [Production Method] As an example of this production method, a method for producing cis-1-chloro-3,3,3-trifluoropropene (1233zd(Z)) will be described.

[0029] 1233zd can be obtained according to the following scheme by reacting 1,1,1,3,3-tetrachloropropane (240fa) with hydrogen fluoride. [Chemical Formula]

[0030] In the composition obtained by the fluorination reaction of 240fa, although depending on the reaction conditions, usually, cis-1-chloro-3,3,3-trifluoropropene (1233zd(Z)) and trans-1-chloro-3,3,3-trifluoropropene (1233zd(E)) are contained in a predetermined ratio. Also, in this reaction, not only 1233zd as the main component, but also other halides may be by-produced. Although it also depends on the reaction conditions, for example, 3-chloro-1,1,1,3-tetrafluoropropane (244fa), 2-chloro-1,1,1,3,3-pentafluoropropane (235da), etc. are by-produced as halides. 244fa and 235da show azeotropic or azeotrope-like behavior with 1233zd(Z).

[0031] [Purification process] The composition obtained by the fluorination reaction of 240fa is purified to obtain high-purity 1233zd(Z) as the target substance. In this production method, vacuum distillation is carried out to obtain high-purity 1233zd(Z) from the composition containing the azeotrope-like composition of 1233zd(Z) and 244fa.

[0032] As the distillation column that can be used for vacuum distillation, it only needs to have the functions necessary for ordinary vacuum distillation, but it is preferable to use a rectification column such as a tray column or a packed column. The number of theoretical plates of the distillation column is usually 10 to 60 plates, preferably 20 to 50 plates, but it is not limited to this range.

[0033] The pressure in the system in the vacuum distillation process may be set to 50 kPa or less, and it is preferably set to 1 kPa to 30 kPa from the viewpoint of industrial practicality. In particular, during vacuum distillation, the top pressure of the distillation column used is preferably 20 kPa or less, more preferably 10 kPa or less.

[0034] The temperature of the top liquid in the vacuum distillation process is not particularly limited, but from the perspective of industrial practicality, it is preferably set at +20°C or lower, particularly preferably at +10°C or lower, and also preferably set at -20°C or higher. If the temperature of the top liquid is -20°C or higher, an increase in equipment costs such as the enlargement of the cooler can be avoided, so it is easy to adopt industrially. Also, if the temperature of the top liquid is +20°C or lower, the distillation separation efficiency is good. In one embodiment, the temperature of the top liquid in the vacuum distillation process is preferably set at -20°C or higher and +20°C or lower, and particularly preferably set at -20°C or higher and +10°C or lower.

[0035] In addition, in the purification process, vacuum distillation may be performed multiple times. When vacuum distillation is performed two or more times, the same distillation column may be used multiple times, or multiple distillation columns may be used.

[0036] High-purity 1233zd(Z) can be obtained by subjecting a composition containing an azeotropic-like composition of 1233zd(Z) and 244fa to vacuum distillation two or more times. Here, high-purity 1233zd(Z) means 1233zd(Z) in which the content of 244fa is 3% by mass or less, preferably 1% by mass or less, more preferably 0.5% by mass, and particularly preferably 0.3% by mass, based on the total amount of 1233zd(Z) and 244fa.

[0037] When vacuum distillation is performed two or more times, the distillation process may be carried out continuously, or another process may be interposed between two or more distillation processes. For example, after at least one vacuum distillation, a dehydrohalogenation treatment process can be carried out before the next vacuum distillation. Specifically, after at least one vacuum distillation, a fraction containing 1233zd(Z) as the main component (for example, a fraction containing 30% by weight or more, 50% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, or 95% by weight or more of 1233zd(Z)) is recovered, and a base is added to the recovered fraction to dehydrohalogenate the 244fa and 235da remaining in the fraction. High-purity 1233zd(Z) can be obtained by subjecting the fraction after the dehydrohalogenation treatment to vacuum distillation again.

[0038] When performing the dehydrohalogenation treatment step, it is preferable to add a solubilizing agent that solubilizes the fraction containing 1233zd(Z) and the basic aqueous solution. By coexisting the solubilizing agent, the reaction between the base and 1233zd(Z) can be suppressed, and 244fa and 235da remaining in the fraction can be decomposed. 244fa is converted to the corresponding fluorine-containing olefin (1234ze) by the dehydrochlorination reaction in the dehydrohalogenation treatment step. 235da is converted to the corresponding fluorine-containing olefin (1224xe) by the dehydrofluorination reaction in the dehydrohalogenation treatment step. Since the boiling points of these fluorine-containing olefins generated in the dehydrohalogenation treatment step are sufficiently different from the boiling point of 1233zd(Z), they can be easily separated from 1233zd(Z) by distillation.

[0039] The base used for dehydrohalogenation is not particularly limited, but examples include inorganic bases such as hydroxides, carbonates, phosphates, alkoxides, oxides, and hydrides of alkali metals or alkaline earth metals. Examples of alkali metals include sodium, potassium, and lithium. Examples of alkaline earth metals include calcium and magnesium. Specific examples of inorganic bases include sodium hydroxide, sodium carbonate, sodium phosphate, sodium oxide, sodium hydride, potassium hydroxide, potassium carbonate, potassium phosphate, potassium oxide, potassium hydride, lithium hydroxide, calcium hydroxide, calcium oxide, and magnesium hydroxide. As the inorganic base, sodium hydroxide, sodium carbonate, potassium hydroxide, and potassium carbonate are preferable, and sodium hydroxide with good availability is most preferable. These bases may be used alone or in combination of two or more.

[0040] The amount of base in the basic aqueous solution to be added depends on the amounts of 244fa and 235da in the fraction. For 1 mol of 235da and / or 244fa, an inorganic base amount of 1.5 to 4 molar equivalents (here, "equivalent" represents chemical equivalent) is preferable, and particularly 2 to 3 molar equivalents is preferable.

[0041] The solubilizer assists in the solubility of 1233zd(Z) in the fraction and the aqueous solution of the inorganic base. As the solubilizer, a phase transfer catalyst or a water-soluble organic substance such as alcohol or ketone is preferred.

[0042] Examples of phase transfer catalysts include quaternary ammonium compounds such as ammonium fluoride, ammonium chloride, ammonium bromide, ammonium iodide, ammonium hydroxide, crown ethers, calixarenes, cyclophanes, cyclodextrins, phosphonium compounds, and pyridinium compounds. Specifically, tetrabutylammonium fluoride, benzyldimethylalkylammonium chloride, 1-butyl-1-methylpyrrolidinium chloride, phenyltriethylammonium chloride, 1-butyl-1-methylpiperidinium bromide, trimethyl-3-trifluoromethylphenylammonium bromide, trimethyl-α,α,α-trifluoro-m-tolylammonium hydroxide, hexadecyltrimethylammonium hydroxide, trimethylphenylammonium iodide, 2,3-benzo-1,4,7,10-tetraoxadodeca-2-ene, 24-crown 8-ether, triphenyl(2-chlorobenzyl)phosphonium chloride, 4-(dimethylamino)-1-(triphenylmethyl)pyridinium chloride can be mentioned.

[0043] As the water-soluble organic substance, a compound that is completely miscible with water at room temperature can be used. Examples of the inorganic base include alcohols, polyalcohols, amides, ketones, ethers, polyethers, and cyclic ethers. Considering availability and the treatment of waste solutions, alcohols are preferred as the water-soluble organic substance.

[0044] The alcohol as a compatibilizer is not particularly limited, but alcohols having 1 to 4 carbon atoms are preferred. Specifically, single substances or mixtures of general-purpose alcohols such as methanol, ethanol, isopropanol, normal propanol, n-butanol, s-butanol, and t-butanol are preferred, and methanol and ethanol are particularly preferred. The addition amount of the alcohol is preferably 5 to 40% by mass, particularly preferably 10 to 30% by mass, based on the fraction.

[0045] [Second Embodiment] [Manufacturing Method] As an example of this manufacturing method, a method for manufacturing cis-1,2-dichloro-3,3,3-trifluoropropene (also referred to as HCFO-1223xd(Z) or 1223xd(Z)) will be described.

[0046] 1223xd(Z) can be produced by the dehydrochlorination reaction of 1,1,2-trichloro-3,3,3-trifluoropropane (also referred to as HCFC-233da or 233da). In the composition obtained by this reaction, although depending on the reaction conditions, usually 1223xd(Z) and E-1,2-dichloro-3,3,3-trifluoropropene (also referred to as HCFO-1223xd(E) or 1223xd) are contained in a predetermined ratio. Further, this composition may contain 1,1-dichloro-3,3,3-trifluoropropene (also referred to as HCFO-1223za or 1223za). 1223xd(E) and / or 1223za exhibit azeotropic or azeotrope-like behavior with 1223xd(Z).

[0047] [Purification Step] The composition obtained by the dehydrochlorination reaction of 233da is purified to obtain high-purity 1223xd(Z) as the target substance. In this manufacturing method, vacuum distillation is performed to obtain high-purity 1223xd(Z) from the composition containing the azeotrope-like composition of 1223xd(Z) and 1223xd(E) and / or 1223za.

[0048] As the distillation column that can be used for vacuum distillation, it only needs to have the functions necessary for ordinary vacuum distillation, but it is preferable to use a rectification column such as a tray column or a packed column. The theoretical number of trays of the distillation column is usually 10 to 60 trays, preferably 20 to 50 trays, but it is not limited to this range.

[0049] The pressure inside the system in the vacuum distillation process may be set to 50 kPa or less, and it is preferably set to 1 kPa to 20 kPa from the viewpoint of industrial practicality. In particular, during vacuum distillation, the top pressure of the distillation column to be used is preferably 10 kPa or less, more preferably 5 kPa or less.

[0050] The top liquid temperature in the vacuum distillation process is not particularly limited, but from the viewpoint of industrial practicality, it is preferably set to +20°C or lower, and it is also preferably set to -20°C or higher. If the top liquid temperature is -20°C or higher, an increase in equipment costs such as the enlargement of the cooler can be avoided, so it is easy to adopt industrially. Also, if the top liquid temperature is +20°C or lower, the distillation separation efficiency is good. In one embodiment, the top liquid temperature in the vacuum distillation process is preferably set to -20°C or higher and +20°C or lower.

[0051] Also in this embodiment, in the purification process, vacuum distillation may be performed multiple times. When vacuum distillation is performed two or more times, the same distillation column may be used multiple times, or multiple distillation columns may be used.

[0052] By subjecting a composition containing an azeotrope-like composition of 1223xd(Z) and 1223xd(E) and / or 1223za to vacuum distillation two or more times, high-purity 1223xd(Z) can be obtained. Here, high-purity 1223xd(Z) means 1223xd(Z) in which the content of 1223xd(E) and / or 1223za is 3% by mass or less, preferably 1% by mass or less, more preferably 0.5% by mass, and particularly preferably 0.3% by mass with respect to the total amount of 1223xd(Z), 1223xd(E), and / or 1223za.

[0053] In addition, when vacuum distillation is carried out two or more times, the distillation process may be carried out continuously, or another process such as a dehydrohalogenation treatment process for impurities may be interposed between two or more distillation processes. Since the details of the dehydrohalogenation treatment process are the same as those of the first embodiment described above, duplicate explanations are omitted. Also, when carrying out the dehydrohalogenation treatment process, it is preferable to add a compatibilizing agent that compatibilizes the fraction containing 1223xd(Z) and the basic aqueous solution, as in the first embodiment. The base and the compatibilizing agent used for dehydrohalogenation are the same as the base and the compatibilizing agent used for dehydrohalogenation described in the first embodiment. Thereby, the reaction between the base and 1223xd(Z) can be selectively suppressed, and 1223xd(E) and / or 1223za remaining in the fraction can be decomposed. For example, 1223xd(E) and 1223za are converted to 1-chloro-3,3,3-trifluoropropene and 3,3,3-trifluoropropionic acid.

[0054] [Third Embodiment] [Manufacturing Method] As an example of this manufacturing method, a method for manufacturing cis-1,2-dichloro-3,3-difluoropropene (hereinafter also referred to as HCFO-1232xd(Z) or 1232xd(Z)) will be described.

[0055] 1232xd(Z) can be produced by reacting 1,2,3,3-tetrachloropropene (also referred to as HCO-1230xd or 1230xd) with hydrogen fluoride. In the composition obtained by this reaction, usually 1232xd(Z) and trans-1,2-dichloro-3,3-difluoropropene (hereinafter also referred to as HCFO-1232xd(E) or 1232xd(E)) are contained in a predetermined ratio depending on the reaction conditions. 1232xd(E) exhibits azeotropic or azeotrope-like behavior with 1232xd(Z).

[0056] [Purification Process] Purify the composition obtained by the fluorination reaction of HCO-1230xd to obtain the target substance 1232xd(Z) with high purity. In this production method, vacuum distillation is performed to obtain high-purity 1232xd(Z) from a composition containing an azeotropic-like composition of 1232xd(Z) and 1232xd(E).

[0057] As the distillation column that can be used for vacuum distillation, it only needs to have the functions necessary for ordinary vacuum distillation, but it is preferable to use a rectification column such as a tray column or a packed column. The number of theoretical plates of the distillation column is usually 10 to 60 plates, preferably 20 to 50 plates, but it is not limited to this range.

[0058] The pressure inside the system in the vacuum distillation step may be set to 50 kPa or less, and it is preferably set to 1 kPa to 20 kPa from the viewpoint of industrial practicality. In particular, during vacuum distillation, the top pressure of the distillation column used is preferably 10 kPa or less, more preferably 5 kPa or less.

[0059] The top liquid temperature in the vacuum distillation step is not particularly limited, but from the viewpoint of industrial practicality, it is preferably set to +20°C or less, and it is also preferably set to -20°C or more. If the top liquid temperature is -20°C or more, an increase in equipment costs such as an increase in the size of the cooler can be avoided, so it is easy to adopt industrially. Also, if the top liquid temperature is +20°C or less, the distillation separation efficiency is good. In one embodiment, the top liquid temperature in the vacuum distillation step is preferably set to -20°C or more and +20°C or less.

[0060] Also in this embodiment, in the purification step, vacuum distillation may be performed multiple times. When vacuum distillation is performed two or more times, the same distillation column may be used multiple times, or a plurality of distillation columns may be used.

[0061] By subjecting a composition containing an azeotrope-like composition of 1232xd(Z) and 1232xd(E) to vacuum distillation two or more times, high-purity 1232xd(Z) can be obtained. Here, high-purity 1232xd(Z) means 1232xd(Z) in which the content of 1232xd(E) is 3% by mass or less, preferably 1% by mass or less, more preferably 0.5% by mass, and particularly preferably 0.3% by mass, based on the total amount of 1232xd(Z) and 1232xd(E).

[0062] Also, when performing vacuum distillation two or more times, the distillation process may be carried out continuously, or another process such as a dehydrohalogenation treatment process for impurities may be interposed between two or more distillation processes. Since the details of the dehydrohalogenation treatment process are the same as those of the first embodiment described above, duplicate explanations are omitted.

[0063] [Modification Example] As a modification of this production method, a method for recovering trans-1-chloro-3,3,3-trifluoropropene (1233zd(E)) will be described.

[0064] 1,1,1,3,3-pentafluoropropane (also referred to as HFC-245fa or 245fa) is obtained by fluorinating 1233zd(E). Depending on the reaction conditions, the composition obtained by fluorinating 1233zd(E) may contain 1,1,1,3,3-pentafluoropropane (245fa) and unreacted 1233zd(E) in a predetermined ratio. 245fa shows azeotropic or azeotrope-like behavior with 1233zd(E). If unreacted 1233zd(E) can be recovered from the obtained composition, the recovered 1233zd(E) can be reused as a raw material for 245fa.

[0065] [Purification Process] The composition obtained by the fluorination reaction of 1233zd(E) is purified to obtain 245fa or high-purity 1233zd(E). In this purification method, vacuum distillation is performed to obtain high-purity 1233zd(E) from a composition containing an azeotrope-like composition of 1233zd(E) and 245fa.

[0066] As the distillation column that can be used for vacuum distillation, it only needs to have the functions necessary for ordinary vacuum distillation, but it is preferable to use a rectification column such as a tray column or a packed column. The theoretical number of plates of the distillation column is usually 10 to 60 plates, preferably 20 to 50 plates, but it is not limited to this range.

[0067] The pressure inside the system in the vacuum distillation process may be set to 50 kPa or less, and it is preferably set to 1 kPa to 50 kPa from the viewpoint of industrial practicality. In particular, during vacuum distillation, the top pressure of the distillation column to be used is preferably 40 kPa or less, more preferably 30 kPa or less.

[0068] The top liquid temperature in the vacuum distillation process is not particularly limited, but from the viewpoint of industrial practicality, it is preferably set to +20°C or less, and it is also preferably set to -20°C or more. If the top liquid temperature is -20°C or more, an increase in equipment costs such as enlargement of the cooler can be avoided, so it is easy to adopt industrially. Also, if the top liquid temperature is +20°C or less, the distillation separation efficiency is good. The top liquid temperature in the vacuum distillation process is preferably set to -20°C or more and +20°C or less.

[0069] In the purification process, similar to the first to third embodiments described above, vacuum distillation may be performed multiple times. Also, when vacuum distillation is performed two or more times, the distillation processes may be performed continuously, or another process such as the above-described dehydrohalogenation treatment process of impurities may be interposed between the two or more distillation processes.

[0070] In the manufacturing method according to the first to third embodiments and the purification method which is a modification example described above, from the viewpoint that they can be separated from each other by vacuum distillation, the (hydro)halocarbon contained in the composition and the impurities contained together with the (hydro)halocarbon preferably all have a standard boiling point of 120°C or less, and more preferably have a standard boiling point of 80°C or less.

[0071] According to the manufacturing methods according to the first to third embodiments described above, when hydrogen fluoride or water remains in the composition, the (hydro)halocarbon can be separated from hydrogen fluoride or water by vacuum distillation of the composition.

[0072] In the above, 1233zd(Z), 1223xd(z), 1232xd(Z) and 1233zd(E) are used as the (hydro)halocarbon, and 244fa, 1223za, 1223xd(E), 1232xd(E) and 245fa are used as the impurities constituting the azeotropic-like composition with these (hydro)halocarbons. However, the (hydro)halocarbon and the impurities showing azeotropic or azeotropic-like behavior with the (hydro)halocarbon are not limited to these.

[0073] In one embodiment, examples of the (hydro)halocarbon contained in the composition and separable from the composition by vacuum distillation include those represented by the general formula (1): C m H a F b Cl c In the general formula (1), m is any integer from 2 to 5, a, b, and c are integers of 0 or more, b + c ≧ 1 is satisfied, and a + b + c = 2m - 2, 2m, or 2m + 2 is satisfied.

[0074] Tables 1 and 2 below show the combinations of the (hydro)halocarbon represented by the general formula (1) contained in the composition and a compound that shows azeotropic or azeotropic-like behavior with the (hydro)halocarbon at normal pressure and is different from the (hydro)halocarbon. However, the (hydro)halocarbon and the compound different from the (hydro)halocarbon are not limited to these.

Table 1

Table 2

[0075] Also, in one embodiment, examples of the (hydro)halocarbon contained in the composition and separable from the composition by vacuum distillation include those represented by the general formula (2): C n H d F e Cl f O g Compounds represented by. In the general formula (2), n is an integer of any one of 3 to 5, d, e, and f are integers of 0 or more, g is an integer of 1 or more, e + f ≧ 1 is satisfied, and d + e + f = 2n - 2, 2n, or 2n + 2 is satisfied.

[0076] Table 3 shows combinations of (hydro)halocarbons represented by the general formula (2) that exhibit azeotropic or azeotrope-like behavior at normal pressure and compounds that exhibit azeotropic or azeotrope-like behavior with the (hydro)halocarbon and are different from the (hydro)halocarbon. However, the (hydro)halocarbon and the compound different from the (hydro)halocarbon are not limited thereto.

Table 3

Examples

[0077] Hereinafter, examples according to the above-described embodiments will be described. However, the embodiments of the present invention are not limited by the following examples. In the following examples, the composition of the organic substance was determined by the area of the chromatogram obtained by gas chromatography equipped with an FID detector unless otherwise noted.

[0078] A composition having the composition shown in Table 4 below was distilled under the distillation conditions shown in Table 5. In the distillation, a 2 L flask was used as the distillation flask, and the number of theoretical plates of the distillation column was 40.

[0079]

Table 4

[0080]

Table 5

[0081] The compositions of Examples 1 to 5 and Comparative Examples 1 to 4 shown in Table 4 were distilled under the conditions shown in Table 5, and the compositions of the recovered products after distillation are shown in Table 6 below. In Table 6 below, Examples 1, 3, 4 and Comparative Examples 1, 3, 4 refer to the compositions of the recovered products distilled from the top of the distillation column, and Examples 2, 5 and Comparative Example 2 refer to the compositions of the bottom residues.

[0082]

Table 6

[0083] Referring to Table 6, when comparing Example 1 with Comparative Example 1, by performing vacuum distillation, 1233zd(Z) (low-boiling substance) is recovered with higher purity than distillation at normal pressure. When comparing Example 2 with Comparative Example 2, by vacuum distillation, 1233zd(E) (high-boiling substance) is recovered with higher purity than distillation at normal pressure. When comparing Examples 3, 4 with Comparative Example 3, by performing vacuum distillation, 1223xd(Z) is recovered with higher purity than distillation at normal pressure. Also, referring to Example 3 and Example 4, in Example 4 where the top temperature during distillation was made lower and the top pressure was set lower, 1223xd(Z) (low-boiling substance) was obtained with higher purity than in Example 3. Also, when comparing Example 5 with Comparative Example 4, by vacuum distillation, 1232xd(Z) (high-boiling substance) is recovered with higher purity than distillation at normal pressure.

[0084] (Example 5: Purification of High-Purity 1233zd by Multi-Stage Vacuum Distillation) In the following Table 7, a composition having the composition shown in the upper part (denoted as "charged composition" in Table 7) was charged into a distillation column with 40 theoretical plates, and vacuum distilled at a distillation pressure of 8 to 10 kPa to recover a composition having the composition shown in the lower part in Table 7 (denoted as "main distillate" in Table 7).

[0085] The above-mentioned main residue of 1208.23 g was charged into a distillation column with 40 theoretical plates and distilled. As shown in Table 8, after performing atmospheric distillation at a distillation pressure of 101 kPa to recover Fraction 1, vacuum distillation was carried out at a distillation pressure of 8 - 9 kPa to recover Fractions 2 - 10. From the fractions recovered by vacuum distillation, 829.13 g of high-purity 1233zd(Z) with a 244fa content of 3% or less can be obtained (Fractions 2 - 9), 749.95 g of high-purity 1233zd(Z) with a 244fa content of 1% or less can be obtained (Fractions 2 - 7), 639.06 g of high-purity 1233zd(Z) with a 244fa content of 0.5% or less can be obtained (Fractions 2 - 6), and 129.44 g of high-purity 1233zd(Z) with a 244fa content of 0.3% or less could be obtained (Fraction 4). Here, Fractions 2 - 10 are the fractions in the order of the timing of removal from the distillation column.

[0086] Also, from the bottom residue, 204.68 g of high-purity 244fa with a 1233zd(Z) content of 1% or less was obtained.

[0087]

Table 7

Table 8

[0088] From the above examples and comparative examples, it can be seen that by purifying the compounds that exhibit azeotropic or azeotrope-like behavior with each other in the composition by vacuum distillation, each component in the composition can be obtained with a higher purity than by atmospheric distillation.

Claims

1. A method for producing a (hydro)halocarbon, comprising a step of subjecting an azeotropic or azeotrope-like composition containing a (hydro)halocarbon and a compound different from the (hydro)halocarbon to vacuum distillation to purify the (hydro)halocarbon.

2. The method for producing a (hydro)halocarbon according to Claim 1, wherein in the vacuum distillation, the top pressure of the distillation column is 50 kPa or less.

3. The method for producing a (hydro)halocarbon according to Claim 1 or 2, wherein in the vacuum distillation, the top temperature of the distillation column is 20°C or less.

4. The method for producing a (hydro)halocarbon according to Claim 1, wherein the standard boiling points of both the (hydro)halocarbon and the compound are 120°C or less.

5. The method for producing a (hydro)halocarbon according to Claim 4, wherein the standard boiling points of both the (hydro)halocarbon and the compound are 80°C or less.

6. The above (hydro)halocarbon is a compound represented by the general formula (1) C ｍ H ａ F ｂ Cl ｃ (where m is any integer from 2 to 5, a, b, and c are integers greater than or equal to 0, b + c ≥ 1 is satisfied, and a + b + c = 2m - 2, 2m, or 2m + 2 is satisfied). The compound is at least one selected from hydrogen fluoride and the compound represented by the general formula (1) (excluding the compound selected as the (hydro)halocarbon). The method for producing a (hydro)halocarbon according to Claim 1.

7. The above (hydro)halocarbon is a compound represented by the general formula (2): C ｎ H ｄ F ｅ Cl ｆ O ｇ (where n is an integer of any one of 3 to 5, d, e, and f are integers of 0 or more, g is an integer of 1 or more, e + f ≧ 1 is satisfied, and d + e + f = 2n - 2, 2n, or 2n + 2 is satisfied). The compound is at least one selected from hydrogen fluoride and the compound represented by the general formula (2) (excluding the compound selected as the (hydro)halocarbon). The method for producing a (hydro)halocarbon according to Claim 1.

8. The (hydro)halocarbon is cis-1-chloro-3,3,3-trifluoropropene, The compound is 3-chloro-1,1,1,3-tetrafluoropropane. The method for producing a (hydro)halocarbon according to Claim 1.

9. The (hydro)halocarbon is cis-1,2-dichloro-3,3,3-trifluoropropene, The compound is 1,1-dichloro-3,3,3-trifluoropropene. The method for producing a (hydro)halocarbon according to Claim 1.

10. The (hydro)halocarbon is cis-1,2-dichloro-3,3-difluoropropene, The compound is trans-1,2-dichloro-3,3-difluoropropene. The method for producing a (hydro)halocarbon according to Claim 1.

11. A step of purifying the (hydro)halocarbon by subjecting an azeotropic or azeotrope-like composition containing the (hydro)halocarbon and a compound different from the (hydro)halocarbon to vacuum distillation, A method for producing a (hydro)halocarbon, wherein the standard boiling points of the (hydro)halocarbon and the compound are both 80 °C or lower.

12. A step of subjecting an azeotropic or azeotrope-like composition containing cis-1-chloro-3,3,3-trifluoropropene and a saturated hydrohalocarbon containing at least 3-chloro-1,1,1,3-tetrafluoropropane to vacuum distillation to recover a fraction containing cis-1-chloro-3,3,3-trifluoropropene as a main component, and A step of further subjecting the fraction to vacuum distillation to obtain cis-1-chloro-3,3,3-trifluoropropene having a 3-chloro-1,1,1,3-tetrafluoropropane content of 3% by mass or less A method for producing cis-1-chloro-3,3,3-trifluoropropene, comprising:

13. After the step of recovering the fraction and before the step of obtaining cis-1-chloro-3,3,3-trifluoropropene, the method further comprises a step of purifying cis-1-chloro-3,3,3-trifluoropropene by contacting the fraction with a base. The method for producing cis-1-chloro-3,3,3-trifluoropropene according to claim 12.

14. The step of purifying the 1-chloro-3,3,3-trifluoropropene is a step of dehydrohalogenating 3-chloro-1,1,1,3-tetrafluoropropane contained in the fraction. The method for producing cis-1-chloro-3,3,3-trifluoropropene according to claim 13.

15. The base is at least one selected from hydroxides, carbonates, phosphates, alkoxides, oxides, and hydrides of alkali metals or alkaline earth metals. The method for producing cis-1-chloro-3,3,3-trifluoropropene according to claim 13.

16. A step of subjecting an azeotropic or azeotrope-like composition containing cis-1,2-dichloro-3,3,3-trifluoropropene and at least one of trans-1,2-dichloro-3,3,3-trifluoropropene and 1,1-dichloro-3,3,3-trifluoropropene to vacuum distillation to recover a fraction containing cis-1,2-dichloro-3,3,3-trifluoropropene as a main component, and The step of further subjecting the fraction to vacuum distillation to obtain cis-1,2-dichloro-3,3,3-trifluoropropene having a content of at least one of trans-1,2-dichloro-3,3,3-trifluoropropene and 1,1-dichloro-3,3,3-trifluoropropene of 3% by mass or less A method for producing cis-1,2-dichloro-3,3,3-trifluoropropene, comprising:

17. After the step of recovering the fraction and before the step of obtaining cis-1,2-dichloro-3,3,3-trifluoropropene, the method for producing cis-1,2-dichloro-3,3,3-trifluoropropene according to claim 16, further comprising a step of contacting the fraction with a base to purify cis-1,2-dichloro-3,3,3-trifluoropropene.

18. The method for producing cis-1,2-dichloro-3,3,3-trifluoropropene according to claim 17, wherein the step of purifying cis-1,2-dichloro-3,3,3-trifluoropropene is a step of dehydrohalogenating at least one of trans-1,2-dichloro-3,3,3-trifluoropropene and 1,1-dichloro-3,3,3-trifluoropropene contained in the fraction.

19. The method for producing cis-1,2-dichloro-3,3,3-trifluoropropene according to claim 17, wherein the base is at least one selected from hydroxides, carbonates, phosphates, alkoxides, oxides, and hydrides of alkali metals or alkaline earth metals.

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