Method for preparing (hydro)halocarbons

Abstract

A method for preparing a (hydro)halocarbon according to one embodiment of the present invention comprises the step of distilling an azeotropic or azeotrope-like composition containing a (hydro)halocarbon and a compound different from the (hydro)halocarbon under reduced pressure to purify the (hydro)halocarbon. A method for preparing a (hydro)halocarbon according to another embodiment of the present invention comprises the step of distilling an azeotropic or azeotrope-like composition containing a (hydro)halocarbon and a compound different from the (hydro)halocarbon under reduced pressure to purify the (hydro)halocarbon, wherein the standard boiling points of the (hydro)halocarbon and the compound are both below 80°C.

Description

Technical Field

[0001] The present invention relates to a process for preparing (hydro)halocarbons. Background Art

[0002] Unsaturated chlorofluorocarbons such as 1-chloro-3,3,3-trifluoropropene (hereinafter, also referred to as HCFO-1233zd, 1233zd) having double bonds in the molecule have low boiling points and very short atmospheric lifetimes, and are compounds with low ozone depletion coefficients and global warming potentials. Therefore, unsaturated chlorofluorocarbons such as HCFO-1233zd are expected to be used as compounds in 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 HCFO-1233zd(Z) and byproducts such as E-1-chloro-3,3,3-trifluoropropene (hereinafter, also referred to as HCFO-1233zd(E), 1233zd(E)) or 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) as a geometric isomer and unreacted hydrogen fluoride is obtained (Patent Document 1). Since HCFC-244fa or HCFC-235da forms an azeotropic composition with the target substance HCFO-1233zd(Z), it is difficult to purify high-purity HCFO-1233zd(Z) from the reaction product.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-103890 Summary of the invention

[0007] Technical Problems to be Solved by the Invention

[0008] One of the technical problems of the present invention is to provide a method for obtaining a high-purity (hydro)halocarbon from an azeotropic or azeotrope-like composition containing a (hydro)halocarbon and a compound different from the (hydro)halocarbon.

[0009] Technical means to solve technical problems

[0010] According to one embodiment of the present invention, a method for preparing a (hydrogen) halocarbon may be provided, which comprises the step of subjecting an azeotropic or azeotrope-like composition containing a (hydrogen) halocarbon and a compound different from the (hydrogen) halocarbon to reduced pressure distillation to purify the (hydrogen) halocarbon.

[0011] In the reduced pressure distillation, the top pressure of the distillation tower may be 50 kPa or less.

[0012] In the reduced pressure distillation, the top temperature of the distillation tower may be 20° C. or lower.

[0013] The (hydro)halogenated hydrocarbon and the compound may both have a standard boiling point of 120° C. or less.

[0014] The (hydro)halogenated hydrocarbon and the compound may both have a standard boiling point of 80° C. or less.

[0015] The (hydro)halogenated hydrocarbon may be of the general formula (1): m H a F b Cl c The compound represented by, in the above general formula (1), m is any integer from 2 to 5, a, b and c are integers greater than 0, satisfying b+c≥1, and satisfying a+b+c=2m-2, a+b+c=2m or a+b+c=2m+2,

[0016] The compound may be at least one selected from hydrogen fluoride and the compound represented by the general formula (1), and the compound does not include a compound selected as the (hydro)halocarbon.

[0017] The (hydro)halogenated hydrocarbon may be of the general formula (2) C n H d F e Cl f O g The compound represented by, in the above general formula (2), n is any integer from 3 to 5, d, e and f are integers greater than 0, g is an integer greater than 1, and satisfies e+f≥1, and satisfies d+e+f=2n-2, d+e+f=2n or d+e+f=2n+2,

[0018] The compound may be at least one selected from hydrogen fluoride and the compound represented by the general formula (2), and the compound does not include a compound selected as the (hydro)halocarbon.

[0019] The (hydro)halocarbon may be cis-1-chloro-3,3,3-trifluoropropene, and the compound may be 3-chloro-1,1,1,3-tetrafluoropropane.

[0020] The (hydro)halocarbon may be cis-1,2-dichloro-3,3,3-trifluoropropene, and the compound may be 1,1-dichloro-3,3,3-trifluoropropene.

[0021] The (hydro)halocarbon may be cis-1,2-dichloro-3,3-difluoropropene, and the compound may be trans-1,2-dichloro-3,3-difluoropropene.

[0022] According to another embodiment of the present invention, a method for preparing a (hydrogen) halocarbon may be provided, comprising the step of subjecting an azeotropic or quasi-azeotropic composition containing a (hydrogen) halocarbon and a compound different from the (hydrogen) halocarbon to reduced pressure distillation to purify the (hydrogen) halocarbon, wherein the standard boiling points of the (hydrogen) halocarbon and the compound are both below 80°C.

[0023] According to another embodiment of the present invention, there is provided a method for preparing high-purity cis-1-chloro-3,3,3-trifluoropropene, comprising: 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 reduced pressure 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 reduced pressure 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.

[0024] After the step of recovering the fraction and before the step of obtaining the cis-1-chloro-3,3,3-trifluoropropene, the method may further include contacting the fraction with a base to purify the cis-1-chloro-3,3,3-trifluoropropene.

[0025] The step of purifying 1-chloro-3,3,3-trifluoropropene may be a step of dehydrohalogenating 3-chloro-1,1,1,3-tetrafluoropropane contained in the fraction.

[0026] Effects of the Invention

[0027] According to one embodiment of the present invention, a high-purity (hydro)halocarbon can be obtained from an azeotropic or azeotrope-like composition containing a (hydro)halocarbon and a compound different from the (hydro)halocarbon. DETAILED DESCRIPTION

[0028] The following describes various embodiments of the present invention. However, the present invention can be implemented in various forms within the scope of the present invention, and it cannot be interpreted that it is limited to the following embodiments. In addition, for the technical effects that are obvious from the description of this specification or the technical effects that can be easily predicted by those skilled in the art, even if they are other technical effects different from the technical effects brought about by the following embodiments, they can still be interpreted as the technical effects brought about by the present invention.

[0029] [Azeotrope-like composition]

[0030] The azeotropic composition is characterized in that the boiling point of the liquid composition is fixed under a specified pressure, and the composition of the vapor (gas phase) of the boiling liquid composition is the same as the composition of the boiling liquid composition (liquid phase). That is, when the liquid composition boils, the azeotropic composition does not cause fractionation of the components of the liquid composition. In contrast, a quasi-azeotropic composition refers to a composition that exhibits the same behavior as an azeotropic composition, characterized in that the boiling point of the liquid composition is basically fixed under a specified pressure, and when the liquid composition volatilizes, it volatilizes with a composition that is basically the same as the composition of the liquid, so the composition of the vapor (gas phase) of the boiling liquid composition changes only to a negligible degree relative to the composition of the boiling liquid composition (liquid phase). That is, a quasi-azeotropic composition is not easy to cause fractionation of the components of the liquid composition when the liquid composition boils. On the other hand, a non-azeotropic composition that is not quasi-azeotropic is characterized in that the gas phase composition of the composition changes with the liquid phase composition of the composition during evaporation or condensation.

[0031] Hereinafter, the method for producing a (hydro)halocarbon according to the present embodiment (hereinafter referred to as the present production method) is described. In the present production method, a (hydro)halocarbon can be selectively produced from an azeotropic or azeotrope-like composition containing a (hydro)halocarbon and an impurity.

[0032] (Hydro)halocarbon is a compound containing at least carbon atoms and halogen atoms in the molecule. (Hydro)halocarbon may further contain hydrogen atoms and / or oxygen atoms. In one embodiment, (Hydro)halocarbon is of the general formula (1): C m H a F b Cl cThe 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 greater than 0, satisfying b+c≥1, and satisfying a+b+c=2m-2, a+b+c=2m or a+b+c=2m+2. The compound represented by the general formula (1) can be prepared, for example, by halogenation (e.g., fluorination, chlorination) of industrially prepared saturated hydrocarbon compounds or unsaturated hydrocarbon compounds, or by dehydrohalogenation (e.g., dehydrofluorination, dehydrochlorination) of industrially prepared halogenated saturated hydrocarbon compounds or halogenated unsaturated hydrocarbon compounds. In addition, in another embodiment, the (hydro)halocarbon is of the general formula (2): C n H d F e Cl f O g In the general formula (2), n is any integer from 3 to 5, d, e and f are integers greater than or equal to 0, g is an integer greater than or equal to 1, and e+f≥1 is satisfied, and d+e+f=2n-2, d+e+f=2n or d+e+f=2n+2 is satisfied. The compound represented by the general formula (2) can be prepared, for example, by hydroxylation of an industrially prepared halogenated saturated hydrocarbon compound or a halogenated unsaturated hydrocarbon compound, or by alkylation of an industrially prepared halogenated saturated / unsaturated ether.

[0033] In these reactions, sometimes by-products are generated while generating (hydrogen) halocarbons. When the by-products form azeotropic or quasi-azeotropic compositions with the (hydrogen) halocarbons as the target product, the purity of the (hydrogen) halocarbons as the target product will decrease. In addition, in these reactions, unreacted raw materials (e.g., hydrogen fluoride for halogenation) may remain. The residual hydrogen fluoride is also one of the main reasons for the purity decrease of the (hydrogen) halocarbons as the target product.

[0034] The inventors of the present application have discovered that by subjecting an azeotropic or azeotrope-like composition containing a (hydrogen) halocarbon as a target product and a compound different from the (hydrogen) halocarbon to reduced pressure distillation, a high-purity (hydrogen) halocarbon as a target product can be obtained, thereby completing the present invention.

[0035] Hereinafter, a preparation method according to an embodiment of the present invention (hereinafter, also referred to as the present preparation method) is described. The present preparation method includes a step of distilling an azeotropic or azeotropic-like composition containing a (hydrogen) halocarbon as a target product and a compound different from the (hydrogen) halocarbon under reduced pressure, thereby purifying the (hydrogen) halocarbon as a target product. The compound different from the (hydrogen) halocarbon refers to a compound that is not the same compound as the (hydrogen) halocarbon as the target product and contains at least carbon atoms and halogen atoms in the molecule. In addition to carbon atoms and halogen atoms, the compound different from the (hydrogen) halocarbon may further contain hydrogen atoms in the molecule. The compound different from the (hydrogen) halocarbon may be at least one selected from hydrogen fluoride and the compound represented by the above general formula (1) (wherein, the compound selected as the (hydrogen) halocarbon is not included). In addition, the compound different from the (hydrogen) halocarbon may be at least one selected from hydrogen fluoride and the compound represented by the above general formula (2) (wherein, the compound selected as the (hydrogen) halocarbon is not included).

[0036] [First embodiment]

[0037] [Preparation method]

[0038] As an example of the present production method, a method for producing cis-1-chloro-3,3,3-trifluoropropene (1233zd(Z)) will be described.

[0039] 1233zd can be obtained by reacting 1,1,1,3,3-pentachloropropane (240fa) with hydrogen fluoride according to the following scheme.

[0040] [Chemical formula 1]

[0041]

[0042] Although it varies depending on the reaction conditions, the composition obtained by the fluorination reaction of 240fa generally contains cis-1-chloro-3,3,3-trifluoropropene (1233zd(Z)) and trans-1-chloro-3,3,3-trifluoropropene (1233zd(E)) in a predetermined ratio. In addition, in this reaction, sometimes not only 1233zd as the main component is produced, but also other halides are produced incidentally. Although it depends on the reaction conditions, for example, 3-chloro-1,1,1,3-tetrafluoropropane (244fa) and 2-chloro-1,1,1,3,3-pentafluoropropane (235da) are produced incidentally as halides. 244fa and 235da exhibit azeotropic or azeotropic-like behavior with 1233zd(Z).

[0043] [Purification process]

[0044] The composition obtained by the fluorination reaction of 240fa is purified to obtain the target substance 1233zd(Z) with high purity. In the present preparation method, reduced pressure distillation is performed to obtain high-purity 1233zd(Z) from a composition containing an azeotrope-like composition of 1233zd(Z) and 244fa.

[0045] As a distillation tower that can be used for vacuum distillation, any distillation tower having the functions required for normal vacuum distillation is used, and preferably a plate tower, a packed tower or the like is used. The number of theoretical plates of the distillation tower is usually 10 to 60, preferably 20 to 50, but is not limited to this range.

[0046] The pressure in the system during the vacuum distillation step can be set to 50 kPa or less, and is preferably set to 1 kPa to 30 kPa from the viewpoint of industrial practicability. In particular, during vacuum distillation, the top pressure of the distillation tower used is preferably 20 kPa or less, and more preferably 10 kPa or less.

[0047] The tower top liquid temperature in the vacuum distillation process is not particularly limited, but from the perspective of industrial practicality, it is preferably set to below +20°C, particularly preferably below +10°C, and preferably above -20°C. If the tower top liquid temperature is above -20°C, the increase in equipment costs such as the large-scale condenser can be avoided, so it is easy to adopt in industry. In addition, if the tower top liquid temperature is below +20°C, the distillation separation efficiency is good. In one embodiment, the tower top liquid temperature in the vacuum distillation process is preferably set to above -20°C and below +20°C, and particularly preferably set to above -20°C and below +10°C.

[0048] In the purification step, the vacuum distillation may be performed multiple times. When the vacuum distillation is performed twice or more, the same distillation tower may be used multiple times, or multiple distillation towers may be used.

[0049] High-purity 1233zd(Z) can be obtained by subjecting a composition containing an azeotrope-like composition of 1233zd(Z) and 244fa to reduced pressure distillation twice or more. Here, high-purity 1233zd(Z) refers to 1233zd(Z) having a 244fa content of 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.

[0050] When performing vacuum distillation more than twice, the distillation process can be performed continuously, or other processes can be inserted between the two or more distillation processes. For example, the dehydrohalogenation process can be performed after performing at least one vacuum distillation and before performing the next vacuum distillation. Specifically, after performing at least one vacuum distillation, a fraction containing 1233zd (Z) as a 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 an alkali is added to the recovered fraction, thereby dehydrohalogenating 244fa and 235da remaining in the fraction. By performing vacuum distillation on the dehydrohalogenated fraction again, a high-purity 1233zd (Z) can be obtained.

[0051] When performing the dehydrohalogenation treatment process, it is preferred to add a compatibilizer that makes the fraction containing 1233zd(Z) compatible with the alkaline aqueous solution. By allowing the compatibilizer to coexist, the reaction between the alkali and 1233zd(Z) can be suppressed, and 244fa and 235da remaining in the fraction can be decomposed. Through the dehydrochlorination reaction in the dehydrohalogenation treatment process, 244fa is converted into the corresponding fluorinated olefin (1234ze). Through the dehydrofluorination reaction in the dehydrohalogenation treatment process, 235da is converted into the corresponding fluorinated olefin (1224xe). Since the boiling points of these fluorinated olefins generated in the dehydrohalogenation treatment process are sufficiently different from the boiling points of 1233zd(Z), they can be easily separated from 1233zd(Z) by distillation.

[0052] The base used in the dehydrohalogenation is not particularly limited, and inorganic bases such as hydroxides, carbonates, phosphates, alkoxides, oxides, and hydrides of alkali metals or alkaline earth metals can be listed. As alkali metals, for example, sodium, potassium, lithium, etc. can be listed. As alkaline earth metals, for example, calcium, magnesium, etc. can be listed. As inorganic bases, specifically, 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 can be listed. As inorganic bases, sodium hydroxide, sodium carbonate, potassium hydroxide, and potassium carbonate are preferred, and sodium hydroxide with good availability is most preferred. These bases can be used alone or in combination of two or more.

[0053] The amount of alkali in the alkaline aqueous solution to be added depends on the amount of 244fa and 235da in the fraction. Preferably, the amount of inorganic base is 1.5 to 4 molar equivalents (wherein "equivalent" means chemical equivalent) per 1 mole of 235da and / or 244fa, and particularly preferably, the amount of inorganic base is 2 to 3 molar equivalents per 1 mole of 235da and / or 244fa.

[0054] The compatibilizer assists the compatibility of 1233zd(Z) in the fraction with the inorganic alkali aqueous solution. The compatibilizer is preferably a phase transfer catalyst or a water-soluble organic substance such as an alcohol or a ketone.

[0055] Examples of the phase transfer catalyst include quaternary ammonium compounds such as ammonium fluoride, ammonium chloride, ammonium bromide, ammonium iodide, and ammonium hydroxide, crown ethers, calixarene, cyclophanes, cyclodextrins, phosphonium compounds, and pyridinium compounds. Specifically, examples include tetrabutylammonium fluoride, benzyldimethylalkylammonium chloride, 1-butyl-1-methylpyrrolium 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-tetraoxadodec-2-ene, 24-crown 8-ether, triphenyl(2-chlorobenzyl)phosphonium chloride, and 4-(dimethylamino)-1-(trityl)pyridinium chloride.

[0056] As the water-soluble organic matter, a compound that is completely miscible with water at room temperature can be used. As the water-soluble organic matter, for example, alcohols, polyols, amides, ketones, ethers, polyethers, and cyclic ethers can be listed. If the availability and the treatment of waste solution are taken into consideration, alcohols are preferred as the water-soluble organic matter.

[0057] The alcohol used as the compatibilizer is not particularly limited, but an alcohol having 1 to 4 carbon atoms is preferred. Specifically, a single alcohol or a mixture of general-purpose alcohols such as methanol, ethanol, isopropanol, n-propanol, n-butanol, sec-butanol, and tert-butanol is preferred, and methanol and ethanol are particularly preferred. The amount of alcohol added is preferably 5 to 40% by mass, particularly preferably 10 to 30% by mass, relative to the fraction.

[0058] [Second embodiment]

[0059] [Preparation method]

[0060] As an example of the present production method, a method for producing cis-1,2-dichloro-3,3,3-trifluoropropene (also referred to as HCFO-1223xd(Z), 1223xd(Z)) will be described.

[0061] 1223xd(Z) can be prepared by dehydrochlorination of 1,1,2-trichloro-3,3,3-trifluoropropane (also known as HCFC-233da, 233da). Although it varies depending on the reaction conditions, the composition obtained by the reaction generally contains 1223xd(Z) and E-1,2-dichloro-3,3,3-trifluoropropene (also known as HCFO-1223xd(E, 1223xd) in a predetermined ratio. In addition, the composition sometimes contains 1,1-dichloro-3,3,3-trifluoropropene (also known as HCFO-1223za, 1223za). 1223xd(E) and / or 1223za exhibit azeotropic or azeotropic-like behavior with 1223xd(Z).

[0062] [Purification process]

[0063] The composition obtained by the dehydrochlorination reaction of 233Da is purified to obtain the target substance 1223xd(Z) with high purity. In the present preparation method, reduced pressure distillation is performed to obtain high-purity 1223xd(Z) from a composition containing an azeotrope-like composition of 1223xd(Z) and 1223xd(E) and / or 1223za.

[0064] As a distillation tower that can be used for vacuum distillation, any distillation tower having the functions required for normal vacuum distillation is used, and preferably a plate tower, a packed tower or the like is used. The number of theoretical plates of the distillation tower is usually 10 to 60, preferably 20 to 50, but is not limited to this range.

[0065] The pressure in the system during the vacuum distillation step can be set to 50 kPa or less, but is preferably set to 1 kPa to 20 kPa from the viewpoint of industrial practicability. In particular, during vacuum distillation, the top pressure of the distillation tower used is preferably 10 kPa or less, more preferably 5 kPa or less.

[0066] The tower top liquid temperature in the vacuum distillation step is not particularly limited, but from the perspective of industrial applicability, it is preferably set to +20°C or less, and preferably set to -20°C or more. If the tower top liquid temperature is above -20°C, the increase in equipment costs such as the large-scale condenser can be avoided, so it is easy to adopt in industry. In addition, if the tower top liquid temperature is below +20°C, the distillation separation efficiency is good. In one embodiment, the tower top liquid temperature in the vacuum distillation step is preferably set to -20°C or more and +20°C or less.

[0067] In this embodiment, the vacuum distillation may be performed multiple times in the purification step. When the vacuum distillation is performed twice or more, the same distillation tower may be used multiple times, or multiple distillation towers may be used.

[0068] High-purity 1223xd(Z) can be obtained by subjecting a composition containing a quasi-azeotrope composition of 1223xd(Z) and 1223xd(E) and / or 1223za to reduced pressure distillation twice or more. Here, high-purity 1223xd(Z) refers to 1223xd(Z) having a content of 1223xd(E) and / or 1223za of 3% by mass or less, preferably 1% by mass or less, further preferably 0.5% by mass, and particularly preferably 0.3% by mass, relative to the total amount of 1223xd(Z), 1223xd(E) and / or 1223za.

[0069] In addition, when performing reduced pressure distillation more than twice, the distillation process can be carried out continuously, and other processes such as the dehydrohalogenation treatment process of impurities can also be inserted between the distillation processes more than twice. The details of the dehydrohalogenation treatment process are the same as those of the first embodiment described above, so repeated descriptions are omitted. In addition, when performing the dehydrohalogenation treatment process, as in the first embodiment, it is preferred to add a compatibilizer that makes the fraction containing 1223xd (Z) compatible with the alkaline aqueous solution. As the alkali and compatibilizer used in dehydrohalogenation, the alkali and compatibilizer used in dehydrohalogenation described in the first embodiment are the same. Thus, the reaction of the alkali with 1223xd (Z) can be selectively suppressed, and the 1223xd (E) and / or 1223za remaining in the fraction can be decomposed. For example, 1223xd (E) or 1223za is converted into 1-chloro-3,3,3-trifluoropropylene or 3,3,3-trifluoropropionic acid.

[0070] [Third embodiment]

[0071] [Preparation method]

[0072] As an example of the present production method, a method for producing cis-1,2-dichloro-3,3-difluoropropene (hereinafter, also referred to as HCFO-1232xd(Z), 1232xd(Z)) will be described.

[0073] 1232xd(Z) can be prepared by reacting 1,2,3,3-tetrachloropropene (also referred to as HCO-1230xd, 1230xd) with hydrogen fluoride. Although it varies depending on the reaction conditions, the composition obtained by the reaction generally contains 1232xd(Z) and trans-1,2-dichloro-3,3-difluoropropene (hereinafter also referred to as HCFO-1232xd(E), 1232xd(E)) at a predetermined ratio. 1232xd(E) and 1232xd(Z) exhibit azeotropic or azeotropic-like behavior.

[0074] [Purification process]

[0075] The composition obtained by the fluorination reaction of HCO-1230xd is purified to obtain the target substance 1232xd(Z) with high purity. In the present preparation method, reduced pressure distillation is performed to obtain high-purity 1232xd(Z) from a composition containing a quasi-azeotropic composition of 1232xd(Z) and 1232xd(E).

[0076] As a distillation tower that can be used for vacuum distillation, any distillation tower having the functions required for normal vacuum distillation is used, and preferably a plate tower, a packed tower or the like is used. The number of theoretical plates of the distillation tower is usually 10 to 60, preferably 20 to 50, but is not limited to this range.

[0077] The pressure in the system during the vacuum distillation step can be set to 50 kPa or less, but is preferably set to 1 kPa to 20 kPa from the viewpoint of industrial practicability. In particular, during vacuum distillation, the top pressure of the distillation tower used is preferably 10 kPa or less, more preferably 5 kPa or less.

[0078] The tower top liquid temperature in the vacuum distillation step is not particularly limited, but from the perspective of industrial applicability, it is preferably set to +20°C or less, and preferably set to -20°C or more. If the tower top liquid temperature is above -20°C, the increase in equipment costs such as the large-scale condenser can be avoided, so it is easy to adopt in industry. In addition, if the tower top liquid temperature is below +20°C, the distillation separation efficiency is good. In one embodiment, the tower top liquid temperature in the vacuum distillation step is preferably set to -20°C or more and +20°C or less.

[0079] In this embodiment, the vacuum distillation may be performed multiple times in the purification step. When the vacuum distillation is performed twice or more, the same distillation tower may be used multiple times, or multiple distillation towers may be used.

[0080] By subjecting a composition containing a quasi-azeotrope composition of 1232xd(Z) and 1232xd(E) to reduced pressure distillation twice or more, high-purity 1232xd(Z) can be obtained. Here, high-purity 1232xd(Z) refers to 1232xd(Z) having a 1232xd(E) content of 3% by mass or less, preferably 1% by mass or less, further preferably 0.5% by mass, and particularly preferably 0.3% by mass relative to the total amount of 1232xd(Z) and 1232xd(E).

[0081] When performing two or more vacuum distillations, the distillation process may be performed continuously, or another process such as a dehydrohalogenation process of impurities may be inserted between the two or more distillation processes. The details of the dehydrohalogenation process are the same as those of the first embodiment described above, and therefore repeated descriptions are omitted.

[0082] [Modifications]

[0083] As a modification of the present production method, a method for recovering trans-1-chloro-3,3,3-trifluoropropene (1233zd(E)) will be described.

[0084] 1,1,1,3,3-pentafluoropropane (also referred to as HFC-245fa, 245fa) can be obtained by fluorinating 1233zd(E). Although it varies depending on the reaction conditions, the composition obtained by fluorinating 1233zd(E) sometimes contains 1,1,1,3,3-pentafluoropropane (245fa) and unreacted 1233zd(E) in a predetermined ratio. 245fa and 1233zd(E) exhibit azeotropic or azeotropic-like behavior. If the unreacted 1233zd(E) can be recovered from the obtained composition, the recovered 1233zd(E) can be reused as a raw material for 245fa.

[0085] [Purification process]

[0086] The composition obtained by the fluorination reaction of 1233zd(E) is purified to obtain 245fa or 1233zd(E) at high purity. In the present purification method, reduced pressure distillation is performed to obtain high-purity 1233zd(E) from a composition containing an azeotrope-like composition of 1233zd(E) and 245fa.

[0087] As a distillation tower that can be used for vacuum distillation, any distillation tower having the functions required for normal vacuum distillation is used, and preferably a plate tower, a packed tower or the like is used. The number of theoretical plates of the distillation tower is usually 10 to 60, preferably 20 to 50, but is not limited to this range.

[0088] The pressure in the system during the vacuum distillation step can be set to 50 kPa or less, but is preferably set to 1 kPa to 50 kPa from the viewpoint of industrial practicability. In particular, during vacuum distillation, the top pressure of the distillation tower used is preferably 40 kPa or less, more preferably 30 kPa or less.

[0089] The tower top liquid temperature in the vacuum distillation step is not particularly limited, but from the perspective of industrial applicability, it is preferably set to +20°C or less, and preferably set to -20°C or more. If the tower top liquid temperature is -20°C or more, it is possible to avoid an increase in equipment costs such as a large-scale condenser, so it is easy to adopt in industry. In addition, if the tower top liquid temperature is +20°C or less, the distillation separation efficiency is good. The tower top liquid temperature in the vacuum distillation step is preferably set to -20°C or more and +20°C or less.

[0090] In the purification process, as in the first to third embodiments described above, multiple vacuum distillations may be performed. In addition, when vacuum distillations are performed twice or more, the distillation process may be performed continuously, or other processes such as the above-mentioned dehydrohalogenation process of impurities may be inserted between the two or more distillation processes.

[0091] In the preparation methods of the first to third embodiments and the purification methods of the modified examples described above, from the perspective of being able to be separated from each other by reduced pressure distillation, the (hydro)halocarbons contained in the composition and the impurities contained together with the (hydro)halocarbons preferably have a standard boiling point of less than 120°C, and more preferably have a standard boiling point of less than 80°C.

[0092] According to the production methods of the first to third embodiments described above, when hydrogen fluoride or water remains in the composition, the (hydro)halogenated hydrocarbon can be separated from the hydrogen fluoride or water by distilling the composition under reduced pressure.

[0093] In the above, 1233zd(Z), 1223xd(z), 1232xd(Z) and 1233zd(E) as (hydro)halocarbons and 244fa, 1223za, 1223xd(E), 1232xd(E) and 245fa as impurities that form azeotropic compositions with these (hydro)halocarbons have been exemplified for explanation, but the (hydro)halocarbons and the impurities that exhibit azeotropic or azeotropic-like behavior with the (hydro)halocarbons are not limited to these.

[0094] In one embodiment, examples of the (hydro)halogenated hydrocarbons contained in the composition and separable from the composition by vacuum distillation include those of the general formula (1): 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 greater than 0, b+c≥1, and a+b+c=2m-2, a+b+c=2m or a+b+c=2m+2.

[0095] Tables 1 and 2 below show combinations of (hydrogen)halocarbons represented by the general formula (1) and compounds different from the (hydrogen)halocarbons contained in the composition, wherein the compounds different from the (hydrogen)halocarbons exhibit azeotropic or azeotropic-like behavior with the (hydrogen)halocarbons at normal pressure. However, the (hydrogen)halocarbons and the compounds different from the (hydrogen)halocarbons are not limited thereto.

[0096] [Table 1]

[0097]

[0098] [Table 2]

[0099]

[0100] In one embodiment, the (hydro)halogenated hydrocarbon contained in the composition and separable from the composition by vacuum distillation includes the following: n H d F e Cl f O g In the general formula (2), n is any integer from 3 to 5, d, e and f are integers greater than 0, g is an integer greater than 1, and e+f≥1, and d+e+f=2n-2, d+e+f=2n or d+e+f=2n+2.

[0101] Combinations of (hydrogen)halocarbons represented by general formula (2) and compounds different from the (hydrogen)halocarbons are shown in Table 3. The compounds different from the (hydrogen)halocarbons exhibit azeotropic or azeotropic-like behavior with the (hydrogen)halocarbons at normal pressure. However, the (hydrogen)halocarbons and the compounds different from the (hydrogen)halocarbons are not limited thereto.

[0102] [Table 3]

[0103]

[0104] Example

[0105] Hereinafter, examples implemented according to the above-mentioned embodiment will be described. However, the embodiment of the present invention is not limited to the following examples. In the following examples, unless otherwise noted, the composition of the organic matter is determined by the area of ​​the chromatogram obtained by gas chromatography with a FID detector.

[0106] The composition having the composition shown in the following Table 4 was distilled under the distillation conditions shown in Table 5. In the distillation, a 2 L flask was used as a distillation pot, and the number of theoretical plates of the distillation column was set to 40.

[0107] [Table 4]

[0108]

[0109] [Table 5]

[0110]

[0111] The compositions of the recovered products after distilling the compositions of Examples 1 to 5 and Comparative Examples 1 to 4 shown in Table 4 under the conditions shown in Table 5 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 tower, and Examples 2, 5 and Comparative Example 2 refer to the compositions of the bottoms of the still.

[0112] [Table 6]

[0113]

[0114] Referring to Table 6, it can be seen that when Example 1 is compared with Comparative Example 1, 1233zd (Z) (low boiling point substance) can be recovered with high purity by reduced pressure distillation compared to distillation under normal pressure. When Example 2 is compared with Comparative Example 2, 1233zd (E) (high boiling point substance) can be recovered with high purity by reduced pressure distillation compared to distillation under normal pressure. When Examples 3 and 4 are compared with Comparative Example 3, 1223xd (Z) can be recovered with high purity by reduced pressure distillation compared to distillation under normal pressure. In addition, referring to Example 3 and Example 4, it can be seen that, compared with Example 3, Example 4, in which the tower top temperature is set lower and the tower top pressure is set lower during distillation, can obtain 1223xd (Z) (low boiling point substance) with higher purity. In addition, when Example 5 is compared with Comparative Example 4, 1232xd (Z) (high boiling point substance) can be recovered with high purity by reduced pressure distillation compared to distillation under normal pressure.

[0115] (Example 5: Purification of high-purity 1233zd by multi-stage vacuum distillation)

[0116] A composition having the composition shown in the upper half of the following Table 7 (referred to as "feed composition" in Table 7) was charged into a distillation tower having 40 theoretical plates, and vacuum distillation was performed at a distillation pressure of 8 to 10 kPa to recover a composition having the composition shown in the lower half of Table 7 (referred to as "main fraction" in Table 7).

[0117] 1208.23 g of the main fraction was introduced into a distillation column having a theoretical plate number of 40 and distilled. As shown in Table 8, after atmospheric distillation was performed at a distillation pressure of 101 kPa to recover fraction 1, vacuum distillation was performed at a distillation pressure of 8 to 9 kPa to recover fractions 2 to 10. From the fractions recovered by vacuum distillation, 829.13 g of high-purity 1233zd(Z) having a 244fa content of 3% or less was obtained (fractions 2 to 9), 749.95 g of high-purity 1233zd(Z) having a 244fa content of 1% or less was obtained (fractions 2 to 7), 639.06 g of high-purity 1233zd(Z) having a 244fa content of 0.5% or less was obtained (fractions 2 to 6), and 129.44 g of high-purity 1233zd(Z) having a 244fa content of 0.3% or less was obtained (fraction 4). Here, fractions 2 to 10 are fractions taken out from the distillation column in chronological order.

[0118] Furthermore, 204.68 g of high-purity 244fa having a 1233zd(Z) content of 1% or less was obtained from the pot residue.

[0119] [Table 7]

[0120]

[0121] [Table 8]

[0122]

[0123] According to the above embodiments and comparative examples, it can be seen that, compared with atmospheric distillation, by purifying the compounds in the composition that exhibit azeotropic or azeotrope-like behavior with each other by using reduced pressure distillation, various components in the composition can be obtained with higher purity.

Claims

1. A method for preparing a (hydrogen) halocarbon, comprising the step of distilling an azeotropic or azeotropic-like composition containing a (hydrogen) halocarbon and a compound different from the (hydrogen) halocarbon under reduced pressure to purify the (hydrogen) halocarbon, wherein: The (hydro)halocarbon is cis-1-chloro-3,3,3-trifluoropropene, The compound is 3-chloro-1,1,1,3-tetrafluoropropane.

2. The method for preparing a (hydro)halocarbon according to claim 1, wherein: The (hydro)halocarbon and the compound are compositions obtained by fluorination of 1,1,1,3,3-pentachloropropane.

3. A method for preparing a (hydrogen) halocarbon, comprising the step of distilling an azeotropic or azeotropic-like composition containing a (hydrogen) halocarbon and a compound different from the (hydrogen) halocarbon under reduced pressure to purify the (hydrogen) halocarbon, wherein: The (hydro)halocarbon is cis-1,2-dichloro-3,3,3-trifluoropropene, The compound is at least one of trans-1,2-dichloro-3,3,3-trifluoropropene and 1,1-dichloro-3,3,3-trifluoropropene.

4. A method for preparing a (hydrogen) halocarbon, comprising the step of distilling an azeotropic or azeotropic-like composition containing a (hydrogen) halocarbon and a compound different from the (hydrogen) halocarbon under reduced pressure to purify the (hydrogen) halocarbon, wherein: The (hydro)halocarbon is cis-1,2-dichloro-3,3-difluoropropene, The compound is at least one of trans-1,2-dichloro-3,3-difluoropropene, hydrogen fluoride and water.

5. A method for preparing a (hydrogen) halocarbon, comprising the step of distilling an azeotropic or azeotrope-like composition containing a (hydrogen) halocarbon and a compound different from the (hydrogen) halocarbon under reduced pressure to purify the (hydrogen) halocarbon, wherein: The (hydro)halocarbon is trans-1-chloro-3,3,3-trifluoropropene, The compound is at least one of 1,1,1,3,3-pentafluoropropane, 2-chloro-3,3,3-trifluoropropene, cis-1-chloro-1,3,3,3-tetrafluoropropene, 2-chloro-1,3,3,3-tetrafluoropropene, hydrogen fluoride and water.

6. A method for preparing a (hydrogen) halocarbon, comprising the step of distilling an azeotropic or azeotrope-like composition containing a (hydrogen) halocarbon and a compound different from the (hydrogen) halocarbon under reduced pressure to purify the (hydrogen) halocarbon, wherein: The (hydro)halocarbon is trans-1-chloro-3,3,3-trifluoropropene, The compound is 1,1,1,3,3-pentafluoropropane.

7. The method for producing a (hydro)halocarbon according to any one of claims 1 to 6, wherein: In the reduced pressure distillation, the top pressure of the distillation tower is 50 kPa or less.

8. The method for producing a (hydro)halocarbon according to any one of claims 1 to 6, wherein: In the reduced pressure distillation, the top temperature of the distillation tower is 20° C. or lower.

9. The method for producing a (hydro)halocarbon according to any one of claims 1 to 6, wherein: The standard boiling points of the (hydro)halogenated hydrocarbon and the compound are both 120° C. or lower.

10. The method for preparing a (hydro)halocarbon according to claim 9, wherein: The standard boiling points of the (hydro)halogenated hydrocarbon and the compound are both 80° C. or lower.

11. A method for preparing cis-1-chloro-3,3,3-trifluoropropene, comprising: 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 reduced pressure 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 reduced pressure 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.

12. The method for preparing cis-1-chloro-3,3,3-trifluoropropene according to claim 11, wherein: The (hydro)halocarbon and the compound are compositions obtained by fluorination of 1,1,1,3,3-pentachloropropane.

13. The method for preparing cis-1-chloro-3,3,3-trifluoropropene according to claim 11 or 12, further comprising, after the step of recovering the fraction and before the step of obtaining the cis-1-chloro-3,3,3-trifluoropropene, a step of contacting the fraction with a base to purify cis-1-chloro-3,3,3-trifluoropropene.

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

15. The method for preparing cis-1-chloro-3,3,3-trifluoropropene according to claim 13, wherein: The step of purifying 1-chloro-3,3,3-trifluoropropene is a step of dehydrohalogenating 3-chloro-1,1,1,3-tetrafluoropropane and 2-chloro-1,1,1,3,3-pentafluoropropane contained in the fraction.

16. The method for preparing cis-1-chloro-3,3,3-trifluoropropene according to claim 13, wherein: The base is at least one selected from the group consisting of hydroxides, carbonates, phosphates, alkoxides, oxides and hydrides of alkali metals or alkaline earth metals.

17. The method for producing cis-1-chloro-3,3,3-trifluoropropene according to claim 13, wherein a compatibilizer is used in the step of contacting the fraction with a base to purify cis-1-chloro-3,3,3-trifluoropropene after the step of recovering the fraction and before the step of obtaining the cis-1-chloro-3,3,3-trifluoropropene.

18. A method for preparing cis-1,2-dichloro-3,3,3-trifluoropropene, comprising: 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 reduced pressure distillation to recover a fraction containing cis-1,2-dichloro-3,3,3-trifluoropropene as a main component; and A step of further subjecting the fraction to reduced pressure distillation to obtain cis-1,2-dichloro-3,3,3-trifluoropropene having a content of 3% by mass or less of at least one of trans-1,2-dichloro-3,3,3-trifluoropropene and 1,1-dichloro-3,3,3-trifluoropropene.

19. The method for preparing cis-1,2-dichloro-3,3,3-trifluoropropene according to claim 18, further comprising, after the step of recovering the fraction and before the step of obtaining the cis-1,2-dichloro-3,3,3-trifluoropropene, a step of contacting the fraction with a base to purify cis-1,2-dichloro-3,3,3-trifluoropropene.

20. The method for preparing cis-1,2-dichloro-3,3,3-trifluoropropene according to claim 19, 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.

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

22. The method for producing cis-1,2-dichloro-3,3,3-trifluoropropene according to claim 19, wherein a compatibilizer is used in the step of contacting the fraction with a base to purify cis-1,2-dichloro-3,3,3-trifluoropropene after the step of recovering the fraction and before the step of obtaining the cis-1,2-dichloro-3,3,3-trifluoropropene.

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