Method for producing 1-chloro-2,2-difluoroethane (HCFC-142) from 1,1,2-trichloroethane (HCC-140)

Abstract

There is provided a method for producing 1-chloro-2,2-difluoroethane (HCFC-142) with less waste, the method including: (a) a step for reacting HCC-140 with hydrogen fluoride (HF) so as to provide a first composition that contains HCFC-142, hydrogen chloride (HCl), HF, and 1,2-dichloroethylene (HCO-1130); and (e) a step for chlorinating a composition containing HCO-1130, which is contained in the first composition, so as to change HCO-1130 into HCC-140, and subsequently recirculating the resultant composition to the step (a).

Description

Process for producing 1-chloro-2,2-difluoroethane (HCFC-142) from 1,1,2-trichloroethane (HCC-140)

[0001] The present disclosure relates to a process for producing 1-chloro-2,2-difluoroethane (HCFC-142) from 1,1,2-trichloroethane (HCC-140).

[0002] 1-Chloro-2,2-difluoroethane (HCFC-142) is known not only as an extender in the production of foams but also as a starting material in the production of pharmaceutical or agricultural chemical compounds. As a method for producing 1-chloro-2,2-difluoroethane (HCFC-142), Patent Document 1 discloses a method for synthesizing HCFC-142 by reacting 1,1,2-trichloroethane (HCC-140) with hydrofluoric acid in the gas phase in the presence of an oxidizing agent and in the presence or absence of a fluorination catalyst.

[0003] It is also well known to prepare HCFC-142 by reacting HCC-140 with hydrofluoric acid in the liquid phase at temperatures between 30 and 180°C and in the presence of a Lewis acid as a catalyst (Patent Document 2). The preparation of HCFC-142 can also be carried out in the gas phase at temperatures between 120 and 400°C in the presence of a chromium-based bulk or supported catalyst (Patent Documents 2 and 3).

[0004] Furthermore, Patent Document 4 describes the preparation of a catalyst for the fluorination of HCC-140 and 1,2-dichloroethylene (HCO-1130) using hydrofluoric acid, and the catalyst is obtained by co-precipitating ferric chloride and magnesium chloride on chromium oxide and alumina oxide, or by co-precipitating chromium nitrate and nickel nitrate on activated carbon, or by doping alumina with zinc chloride. Patent Document 4 discloses that HCFC-142 can be synthesized with a selectivity of 22 to 66% by vapor-phase fluorination of HCC-140 in the presence of a specific fluorination catalyst.

[0005] Japanese Patent No. 6634373 French Patent No. 2783820 European Patent (EP) No. 1008575 International Publication No. 2013 / 053800

[0006] One of the objects of the present disclosure is to provide a method for producing 1-chloro-2,2-difluoroethane (HCFC-142) with little waste.

[0007] The above problem can be solved by the following configuration.

[0008] [1] A method for producing 1-chloro-2,2-difluoroethane (HCFC-142) from 1,1,2-trichloroethane (HCC-140), comprising the steps of: (a) reacting HCC-140 with hydrogen fluoride (HF) to provide a first composition containing HCFC-142, hydrogen chloride (HCl), HF, and 1,2-dichloroethylene (HCO-1130), and (e) chlorinating a composition containing HCO-1130 contained in the first composition to convert HCO-1130 to HCC-140, and then recycling the HCO-1130 to HCC-140. [2] The method according to [1], wherein the chlorination treatment is carried out after purifying the first composition to increase the concentration of HCO-1130.

[0009] [3] The method according to [2], wherein the purification treatment comprises a step of separating and removing at least HCFC-142 and HF from the first composition. [4] The method according to [2], wherein the purification treatment comprises a step of separating and removing HCFC-142, HF, and HCl from the first composition.

[0010] [5] The method according to [2], wherein the purification treatment comprises the steps of: (b) separating HCl from the first composition to provide a second composition containing HCl; and a third composition containing HF, HCFC-142, and HCO-1130; (c) separating HF from the third composition to provide a fourth composition containing HCFC-142 and HCO-1130; and a fifth composition containing HF; and (d) separating HCFC-142 from the fourth composition to provide a composition containing HCFC-142 and a sixth composition containing HCO-1130.

[0011] [6] The method according to any one of [1] to [5], wherein the step (a) is carried out in the presence of a catalyst. [7] The method according to any one of [1] to [6], wherein the chlorination treatment in the step (e) is carried out in the presence of a catalyst. [8] The method according to any one of [1] to [7], wherein the chlorination treatment in the step (e) is carried out in a gas phase or a liquid phase. [9] The method according to any one of [1] to [8], wherein the reaction temperature of the chlorination treatment in the step (e) is 30°C or higher and 220°C or lower.

[10] The method according to any one of [1] to [9], wherein the pressure during the chlorination treatment in the step (e) is normal pressure (0.1 MPa) to 1.0 MPa.

[11] The method according to any one of [1] to

[10] , wherein in the step (e), the total amount of 1,2-dichloro-2-fluoroethane (HCFC-141) and HCFC-142 contained in the composition containing HCO-1130 used in the chlorination treatment is 10 mass% or less.

[12] The method according to any one of [1] to

[11] , wherein in the step (e), the composition containing HCO-1130 used in the chlorination treatment has a water content of 1000 mass ppm or less.

[13] The method according to [5], wherein in the step (d), HCFC-142 is separated from the fourth composition by precision distillation.

[14] The method according to [5], further comprising a step of recycling the fifth composition derived from the step (c) to the step (a).

[15] A method for producing 1-chloro-2,2-difluoroethane (HCFC-142) from 1,1,2-trichloroethane (HCC-140), comprising the step of chlorinating 1,2-dichloroethylene (HCO-1130), a by-product of the production of HCFC-142 from HCC-140, to obtain HCC-140, which is recycled as a raw material.

[0012] According to the present disclosure, it is possible to provide a method for producing 1-chloro-2,2-difluoroethane (HCFC-142) with little waste.

[0013] Hereinafter, each embodiment of the invention disclosed in this application will be described. However, this disclosure can be embodied in various forms without departing from the gist thereof, and should not be construed as being limited to the description of the following exemplary embodiments.

[0014] In this specification, for halogenated hydrocarbons, the abbreviation for the compound is written in parentheses after the compound name, but in this specification, this abbreviation will be used instead of the compound name as necessary. Furthermore, for compounds having geometric isomers, the (E) attached to the name and abbreviation indicates the E-form (trans), and the (Z) attached to the abbreviation indicates the Z-form (cis). When the E-form or Z-form is not specified in the name or abbreviation of the compound, the name or abbreviation is a generic term that includes the E-form, the Z-form, and a mixture of the E-form and the Z-form. In the present disclosure, 1,2-dichloroethylene is usually a mixture of the cis-form and the trans-form. However, only one of these may be present.

[0015] (1) In industrial-scale production, when purifying the target product from a reaction product containing the by-product 1,2-dichloroethylene (HCO-1130), the process can become complicated, leaving room for improvement. Therefore, in this disclosure, a production method capable of simultaneously producing 1-chloro-2,2-difluoroethane (HCFC-142) and suppressing the production of by-products was investigated. (2) The by-product HCO-1130 has low fluorination reactivity and cannot be converted to HCFC-142. Therefore, if the by-product is returned to the recycling process as is, it will remain unreacted. Even if the fluorination reaction proceeds and HCO-1130 is converted to HCFC-142, it is believed that under high-temperature conditions where fluorination proceeds, dehalogenation will proceed preferentially, and HCC-140 will be converted to HCO-1130, and HCO-1130 is expected to remain in the reaction system. Therefore, if the by-product is returned to the recycling step as is, it is believed that HCO-1130 will still remain. If this process is repeated, there is a concern that HCO-1130 will remain in the reaction system, resulting in the production of a large amount of waste as a by-product. For this reason, it has been discovered that HCO-1130 can be returned to HCC-140, which is more easily fluorinated. Below, a method for producing 1-chloro-2,2-difluoroethane (HCFC-142) that suppresses the retention of 1,2-dichloroethylene (HCO-1130) is described.

[0016] The method disclosed herein is a method for producing 1-chloro-2,2-difluoroethane (HCFC-142) from 1,1,2-trichloroethane (HCC-140), comprising the steps of: (a) reacting HCC-140 with hydrogen fluoride (HF) to provide a first composition containing HCFC-142, hydrogen chloride (HCl), HF, and 1,2-dichloroethylene (HCO-1130); and (e) chlorinating a composition containing HCO-1130 contained in the first composition to convert HCO-1130 to HCC-140, which is then recycled to step (a).

[0017] (1. Step (a) Fluorination Treatment of 1,1,2-Trichloroethane (HCC-140)) First, in step (a), 1,1,2-trichloroethane (HCC-140) is reacted with hydrogen fluoride to produce a reaction liquid (also referred to as a "first composition") containing 1-chloro-2,2-difluoroethane (HCFC-142), hydrogen chloride (HCl), hydrogen fluoride (HF), and 1,2-dichloroethylene (HCO-1130). Step (a) can be carried out as either a gas phase reaction or a liquid phase reaction.

[0018] In step (a), HF is preferably used in an amount of 1 to 100 equivalents relative to HCC-140, more preferably 1 to 50 equivalents, and even more preferably 1 to 20 equivalents. When step (a) is a gas-phase reaction, the reaction is carried out in the presence of a catalyst. From the viewpoint of promoting the reaction, chromium catalysts such as activated carbon supported on chromium (chromium-supported activated carbon catalyst) and fluorinated alumina catalyst supported on chromium (chromium-supported fluorinated alumina catalyst) are used as the catalyst. Among these, chromium-supported activated carbon catalysts are preferred. In the case of a gas-phase reaction, the treatment temperature in step (a) is preferably 180 to 220°C from the viewpoint of a general gas-phase reaction. In the case of a liquid-phase reaction, the temperature is preferably 50 to 200°C. Furthermore, an oxidizing agent may not be used in step (a). Furthermore, step (a) is preferably carried out at atmospheric pressure (0.1 MPa) to 1 MPa, more preferably atmospheric pressure to 0.3 MPa. The above pressure indicates the total pressure in the reaction system in step (a).

[0019] In the method of the present disclosure, it is preferable to purify the first composition obtained in step (a) to increase the concentration of HCO-1130, and then to perform the chlorination treatment in step (e) described below. The purification treatment preferably includes a step of separating and removing at least HCFC-142 and unreacted HF in step (a) from the first composition. In the purification treatment, HCl, which is a by-product of step (a), may also be removed. That is, the purification treatment preferably includes a step of separating and removing HCFC-142, HF, and HCl from the first composition.

[0020] Methods for separating and removing HCl include known techniques such as water washing, degassing under reduced pressure, distillation, etc. Methods for separating and removing HF include water washing, distillation, washing with a basic aqueous solution, removal using an adsorbent, separation by liquid separation, etc. Methods for separating and removing HCFC-142 include distillation (rectification and extractive distillation), etc.

[0021] These purification treatments may be performed in any order, and may also be performed simultaneously if possible. For example, water may be added to the first composition to simultaneously wash away HCl and HF.

[0022] Among these, the purification process preferably includes the steps of: (b) separating HCl from the first composition to provide a second composition containing HCl; and a third composition containing HF, HCFC-142, and HCO-1130; (c) separating HF from the third composition to provide a fourth composition containing HCFC-142 and HCO-1130; and a fifth composition containing HF; and (d) separating HCFC-142 from the fourth composition to provide a sixth composition containing HCFC-142 and HCO-1130. Purification performed in the order of steps (b), (c), and (d) allows impurities to be separated and removed in order of lowest boiling point, resulting in high efficiency. Furthermore, HF can be easily separated and recovered. Steps (b) to (d) are described below. Although steps (b) to (d) are known, the method of the present disclosure preferably includes these steps as appropriate as the preferred purification treatment of the present disclosure.

[0023] (2. Step (b) First Separation Treatment) In step (b), HCl is separated from the reaction liquid (first composition) obtained in step (a) and separated into a stream A (also referred to as the "second composition") containing hydrogen chloride (HCl) and a stream B (also referred to as the "third composition") containing hydrogen fluoride (HF), 1-chloro-2,2-difluoroethane (HCFC-142), and 1,2-dichloroethylene (HCO-1130). Methods for separating HCl from the first composition in step (b) include collecting the first composition and then performing distillation, degassing under reduced pressure (degassing under slightly reduced pressure), nitrogen flow, and the like, among which degassing under reduced pressure (degassing under slightly reduced pressure) is preferred.

[0024] (3. Step (c) Second Separation Treatment) Next, in step (c), HF is separated from stream B (third composition) obtained in step (b) to provide an organic phase (also referred to as the "fourth composition") containing 1-chloro-2,2-difluoroethane (HCFC-142) and 1,2-dichloroethylene (HCO-1130), and a non-organic phase (also referred to as the "fifth composition") containing HF. The fourth composition may further contain unreacted 1,1,2-trichloroethane (HCC-140). Methods for separating HF from stream B in step (c) include distillation, degassing under reduced pressure (degassing at a slight reduced pressure), nitrogen flow, washing (washing with water or a basic aqueous solution), adsorption treatment, and separation by a liquid-liquid separation operation. In step (c), a washing step may be included when separating stream B. In the washing step, water, a basic aqueous solution, or the like is mixed with the organic layer to perform two-layer separation, and acid components (mainly HF) present in the system are removed.

[0025] (4. Step (d) Third Separation Treatment) Next, in step (d), HCFC-142 is separated from the organic phase (fourth composition) obtained in step (c) to provide a sixth composition containing 1-chloro-2,2-difluoroethane (HCFC-142) and 1,2-dichloroethylene (HCO-1130). At this time, methods for separating the organic phase include precision distillation and extractive distillation. Among these, it is preferable to separate HCFC-142 from the fourth composition using precision distillation.

[0026] The main fraction 1-chloro-2,2-difluoroethane (HCFC-142) obtained by precision distillation may contain trans-1,2-dichloroethylene (HCO-1130E), which forms an azeotrope with it. For this reason, 1-chloro-2,2-difluoroethane (HCFC-142) and trans-1,2-dichloroethylene (HCO-1130E) may be subjected to extractive distillation. This allows only 1-chloro-2,2-difluoroethane (HCFC-142) to be obtained. The obtained 1-chloro-2,2-difluoroethane (HCFC-142) may be subjected to a dehydration treatment.

[0027] (5. Step (e) Chlorination Treatment) In step (e), the composition containing HCO-1130 contained in the first composition obtained in step (a) is chlorinated with hydrogen chloride to convert HCO-1130 into HCC-140, which is then recycled to step (a). Note that the composition containing HCO-1130 may contain HCO-1130, and may, for example, be one containing only HCO-1130 (HCO-1130 alone) or one containing a compound other than HCO-1130.

[0028] The chlorination treatment may be carried out in the gas phase or the liquid phase. The chlorination treatment is also carried out in the presence of a catalyst. When the chlorination treatment is carried out, the reaction time is preferably 10 hours or less, more preferably 5 hours or less. In the chlorination treatment, HCl is preferably used in an amount of 20 equivalents or less, more preferably 15 equivalents or less, and even more preferably 0.9 to 10 equivalents, relative to the HCO-1130. The chlorination treatment may be carried out under conditions of 30°C to 220°C. The chlorination treatment may be carried out under pressure conditions of atmospheric pressure (0.1 MPa) to 1.0 MPa.

[0029] Furthermore, the raw material for the chlorination treatment may be subjected to a dehydration treatment. The amount of water in the composition containing HCO-1130 used in the chlorination treatment is preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, and particularly preferably 100 ppm by mass or less. The lower limit is not particularly limited, but is, for example, 0.01 ppm by mass or more. Furthermore, the total amount of 1,2-dichloro-2-fluoroethane (HCFC-141) and 1-chloro-2,2-difluoroethane (HCFC-142) contained in the composition containing HCO-1130 used in the chlorination treatment is preferably 10% by mass or less. 1,2-Dichloro-2-fluoroethane (HCFC-141) is a component that may be produced in step (a). The lower limit is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more.

[0030] When the chlorination treatment is carried out in a liquid phase, it is particularly preferable to use HCl in an amount of 0.95 to 2 equivalents relative to HCO-1130. When the chlorination treatment is carried out in a liquid phase, the reaction temperature is desirably 100°C or lower. More preferably, it is 70°C or lower, and even more preferably, it is 30 to 70°C. For example, when the chlorination treatment is carried out in a liquid phase, the reaction temperature is 50°C. It is desirable to use a Lewis acid as the catalyst. In this case, for example, iron(III) chloride or the like may be used as the Lewis acid. The type of Lewis acid is not particularly limited. Specifically, in addition to iron(III) chloride, any of boron trichloride, boron trifluoride, boron tribromide, aluminum chloride, aluminum fluoride, methyldichloroaluminum, dimethylchloroaluminum, trimethylaluminum, aluminum isopropoxide, antimony pentachloride, antimony fluoride, magnesium chloride, magnesium bromide, titanium tetrachloride, titanium tetraisopropoxide, dichlorotitanium bistriflate, biscyclopentadienyltitanium bistriflate, dichlorotitanium bisfluorosulfonate, tin(II) chloride, and tin(II) bistriflate may be used. When the chlorination treatment is carried out in a liquid phase, the amount of the catalyst is preferably 10 mol% or less, more preferably 5 mol% or less, and particularly preferably 2 mol% or less. Furthermore, the amount of the catalyst is preferably 0.1 mol% or more.

[0031] When the chlorination treatment is carried out in the gas phase, it is particularly preferable to use HCl in an amount of 5 to 20 equivalents relative to HCO-1130. When the chlorination treatment is carried out in the gas phase, it is preferably carried out under temperature conditions higher than those in the liquid phase. Furthermore, it is desirable that the reaction temperature be 220°C or lower. More preferably, it is 50 to 150°C, and even more preferably, it is 100 to 130°C. For example, when the chlorination treatment is carried out in the gas phase, the reaction temperature is 120°C. In this case, it is desirable to use a catalyst that can be used at the above-mentioned temperature. Examples include chromium catalysts such as chromium-supported activated carbon catalysts and chromium-supported fluorinated alumina catalysts, and fluorinated alumina. Furthermore, when the chlorination treatment is carried out in the gas phase, an oxidizing agent may or may not be used. When an oxidizing agent is not used, it is possible to prevent a decrease in the yield of the target product, 1,1,2-trichloroethane (HCC-140), which is caused by the reaction of the oxidizing agent with 1,2-dichloroethylene (HCO-1130), which is the raw material for the chlorination reaction.

[0032] It is preferable that the step (e) is a step (e2) in which the residue (also referred to as the "sixth composition") containing 1,2-dichloroethylene (HCO-1130) obtained in the step (d) is chlorinated with hydrogen chloride to convert HCO-1130 into HCC-140, which is then recycled to the step (a). That is, the method of the present disclosure is a method for producing 1-chloro-2,2-difluoroethane (HCFC-142) from 1,1,2-trichloroethane (HCC-140), comprising the steps of: (a) reacting HCC-140 with hydrogen fluoride (HF) to provide a first composition comprising HCFC-142, hydrogen chloride (HCl), HF, and 1,2-dichloroethylene (HCO-1130); (b) separating HCl from the first composition to provide a second composition comprising HCl, and a third composition comprising HF, HCFC-142, and HCO-1130; and (c) separating HF from the third composition to provide a fourth composition comprising HCFC-142 and HCO-1130, and a fifth composition comprising HF. (d) separating HCFC-142 from the fourth composition to provide a sixth composition containing HCFC-142 and HCO-1130; and (e2) chlorinating the sixth composition to convert HCO-1130 into HCC-140, which is then recycled to step (a).

[0033] Furthermore, before the chlorination treatment, the raw material for the chlorination treatment (residue, i.e., the sixth composition) may be subjected to a dehydration treatment. The amount of water in the raw material for the chlorination treatment (residue) after the dehydration treatment is preferably 1,000 ppm by mass or less, more preferably 500 ppm by mass or less, and particularly preferably 100 ppm by mass or less. The lower limit is not particularly limited, but is, for example, 0.01 ppm by mass or more. Furthermore, the total amount of 1,2-dichloro-2-fluoroethane (HCFC-141) and 1-chloro-2,2-difluoroethane (HCFC-142) contained in the raw material for the chlorination treatment (residue, i.e., the sixth composition) is preferably 10% by mass or less. 1,2-Dichloro-2-fluoroethane (HCFC-141) is a component that may be produced in step (a). The lower limit is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more.

[0034] By using one embodiment of the present disclosure, 1,2-dichloroethylene (HCO-1130), a by-product produced in the fluorination process of 1,1,2-trichloroethane (HCC-140) to 1-chloro-2,2-difluoroethane (HCFC-142), is converted to 1,1,2-trichloroethane (HCC-140) by chlorination and recycled, thereby establishing a process for producing 1-chloro-2,2-difluoroethane (HCFC-142) with minimal waste.

[0035] <Modifications> Within the scope of the concept of the present disclosure, a person skilled in the art may conceive of various modifications and alterations, and it is understood that these modifications and alterations also fall within the scope of the present disclosure. For example, to the above-described embodiments, a person skilled in the art may appropriately add, delete, or modify components, or add, omit, or change conditions of steps, and these modifications are also included within the scope of the present disclosure as long as they include the gist of the present disclosure.

[0036] In one embodiment of the present disclosure, an example in which step (a) is performed in the presence of a catalyst has been described, but the present disclosure is not limited thereto. Step (a) may also be performed in the absence of a catalyst.

[0037] In one embodiment of the present disclosure, the HF-containing non-organic phase (fifth composition) obtained in step (c) may be recycled to step (a). That is, the method of the present disclosure may further include a step of recycling the fifth composition derived from step (c) to step (a). This allows for further reduction of waste generated during the production of 1-chloro-2,2-difluoroethane (HCFC-142).

[0038] Furthermore, in one embodiment of the present disclosure, an example has been shown in which 1,2-dichloroethylene (HCO-1130) is produced as an organic substance together with 1-chloro-2,2-difluoroethane (HCFC-142) in the fluorination of 1,1,2-trichloroethane (HCC-140), but the present disclosure is not limited thereto. In addition to 1,2-dichloroethylene (HCO-1130), 1-chloro-2-fluoroethylene (HCFO-1131) or 1,2-dichloro-2-fluoroethane (HCFC-141) may also be produced.

[0039] Another embodiment of the present disclosure is a method for producing 1-chloro-2,2-difluoroethane (HCFC-142) from 1,1,2-trichloroethane (HCC-140), comprising the step of chlorinating 1,2-dichloroethylene (HCO-1130), a by-product of the production of HCFC-142 from HCC-140, to obtain HCC-140, which is recycled as a raw material. The chlorination treatment is the same as in step (e) above.

[0040] Next, the present disclosure will be described in more detail based on examples. Note that the following explanation is intended to facilitate understanding of the present disclosure and is not intended to limit the scope of the present disclosure. In other words, modifications, embodiments, and other examples based on the technical concept of the present disclosure are all included in the present disclosure.

[0041] 1. Fluorination reaction of 1,1,2-trichloroethane (HCC-140) [Example 1] A gas-phase reactor having a reaction tube filled with a chromium-supported activated carbon catalyst was equipped with a metal electric heater and an external heating device (a mantle heater manufactured by Tokyo Kiki Co., Ltd.), and heated while flowing nitrogen gas through the reactor at a flow rate of approximately 200 mL / min. Next, as a catalyst activation treatment, hydrogen fluoride gas was flowed through the reaction tube at a temperature of 200-350°C at a rate of 0.2 g / min.

[0042] While hydrogen fluoride gas was flowing at a flow rate of 0.3 g / min, HCC-140 as a starting material was supplied to the reaction tube through a vaporizer at a flow rate of 0.5 g / min (contact time: 40 seconds). The temperature inside the reaction tube (reaction temperature) during this period was 200°C. After confirming that the reaction was stable, the gas flowing out of the reactor was blown into water to remove acidic gases, and the composition after the reaction was analyzed by gas chromatography. The analysis results of the gas chromatography are shown in Table 1. The analysis results of the starting material (raw material) are also shown.

[0043]

[0044] 1. Chlorination reaction of 1,2-dichloroethylene (HCO-1130) [Example 2] A gas-phase reactor having a reaction tube filled with a chromium-supported fluorinated alumina catalyst was equipped with a metal electric heater and an external heating device (a mantle heater manufactured by Tokyo Kiki Co., Ltd.), and heated while flowing nitrogen gas through the reactor at a flow rate of approximately 200 mL / min. Next, as a catalyst activation treatment, hydrogen fluoride gas was flowed through the reaction tube at a temperature of 200-350°C at a rate of 0.25 g / min.

[0045] While hydrogen chloride gas was flowing at a flow rate of 0.2 g / min, HCO-1130 as a starting material was supplied to the reaction tube through a vaporizer at a flow rate of 0.2 g / min (contact time: 20 seconds). The temperature inside the reaction tube (reaction temperature) during this period was 120°C. After confirming that the reaction was stable, the gas flowing out of the reactor was blown into water to remove acidic gases, and the product was analyzed by gas chromatography. The results of the gas chromatography analysis are shown in Table 2. The analysis results of the starting material (raw material) are also shown.

[0046]

[0047] In Table 1, "Other" refers to components other than HCO-1130E / Z, HCFC-141, and HCC-140 that can be detected by gas chromatography analysis. "-" indicates a value below the lower detection limit (0.01 GC%) by gas chromatography. The same applies to the following tables.

[0048] [Example 3] A chlorination reaction was carried out in the same manner as in Example 2, except that the reaction temperature and contact time were changed. The reaction temperature and contact time in Example 3, as well as the results of gas chromatography analysis of the reaction product, are shown in Table 3. The results of analysis of the starting material (raw material) are also shown.

[0049]

[0050] Example 4 A 300 mL SUS pressure reactor was charged with 0.3 g of iron(III) chloride and 10 g of HCO-1130 as a starting material, and the reactor was sealed. Hydrogen chloride gas was introduced while cooling in an ice bath, and the bath temperature was raised to 70°C and stirred for 2 hours. The internal pressure at this time was 0.5 to 0.1 MPa. After completion of the reaction, the contents and gas were blown into water to remove acidic gases, followed by separation into two layers and analysis of the product by gas chromatography. The analytical results of gas chromatography for Example 4 are shown in Table 4. The analytical results of the starting materials (raw materials) are also shown.

[0051]

[0052] It was confirmed from Examples 2 and 3 that HCO-1130 can be converted to HCC-140 by gas phase chlorination. Moreover, Example 4 suggested that a similar reaction also occurs in liquid phase chlorination.

[0053] 2. Fluorination reaction of 1,2-dichloroethylene (HCO-1130) [Comparative Example 1] A gas-phase reactor having a reaction tube filled with a chromium-supported activated carbon catalyst was equipped with a metal electric heater and an external heating device (a mantle heater manufactured by Tokyo Kiki Co., Ltd.), and heated while flowing nitrogen gas through the reactor at a flow rate of approximately 300 mL / min. Next, hydrogen fluoride gas was flowed through the reaction tube at a rate of 0.6 g / min at a temperature of 200-300°C.

[0054] Hydrogen fluoride gas was supplied to the reaction tube at a flow rate of 0.2 g / min, and HCO-1130 as the starting material was supplied at a flow rate of 0.1 g / min through a vaporizer (contact time: 28 seconds). During this time, the temperature inside the reaction tube (reaction temperature) was 200°C, and the internal pressure was atmospheric pressure (normal pressure). After confirming that the reaction was stable, the gas flowing out of the reactor was blown into water to remove acidic gases, and the product was analyzed by gas chromatography. The reaction temperature and contact time for Comparative Example 1, and the results of gas chromatography analysis of the reaction product are shown in Table 5. The analysis results of the starting material (raw material) are also shown.

[0055]

[0056] Comparative Example 2 A 200 mL SUS pressure reactor was charged with 13.1 g of tin(II) chloride and 24.2 g of HCO-1130 as a starting material, and the reactor was sealed. The bath temperature was raised to 70°C and stirred for 2 hours, then cooled to -78°C and 12.7 g of hydrofluoric acid was added. The mixture was heated to 70°C and aged for 1 hour at an internal pressure of 0.4 MPa. After completion of the reaction, the contents and gas were blown into water to remove acidic gases, followed by separation into two layers and analysis of the product by gas chromatography. The gas chromatography analysis results for Comparative Example 2 are shown in Table 6. The analysis results for the starting materials (raw materials) are also shown.

[0057]

[0058] Comparative Examples 1 and 2 suggest that it is difficult to derive HCFC-142 from HCO-1130 through fluorination reactions in the gas phase and liquid phase. From these results, it is expected that when the organic phase containing HCO-1130 is recycled to the fluorination step (step (a)), unreacted HCO-1130 will remain.

[0059] According to the present disclosure, a method for producing 1-chloro-2,2-difluoroethane (HCFC-142) with less waste can be provided.

[0060] Although the present disclosure has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present disclosure. This application is based on a Japanese patent application (Patent Application No. 2023-188563) filed on November 2, 2023, the contents of which are incorporated herein by reference.

Claims

1. A process for producing 1-chloro-2,2-difluoroethane (HCFC-142) from 1,1,2-trichloroethane (HCC-140), comprising the steps of: (a) reacting HCC-140 with hydrogen fluoride (HF) to provide a first composition containing HCFC-142, hydrogen chloride (HCl), HF, and 1,2-dichloroethylene (HCO-1130); and (e) chlorinating a composition containing HCO-1130 contained in said first composition to convert HCO-1130 to HCC-140, which is then recycled to step (a).

2. The method of claim 1, wherein said first composition is purified to increase the concentration of said HCO-1130 prior to said chlorination.

3. The method according to claim 2, wherein said purification treatment comprises a step of separating and removing at least HCFC-142 and HF from said first composition.

4. The method of claim 2, wherein said purification process includes the step of separating and removing HCFC-142, HF, and HCl from said first composition.

5. The method of claim 2, wherein said purification process comprises the steps of: (b) separating HCl from said first composition to provide a second composition comprising HCl; and a third composition comprising HF, HCFC-142, and HCO-1130; (c) separating HF from said third composition to provide a fourth composition comprising HCFC-142 and HCO-1130; and a fifth composition comprising HF; and (d) separating HCFC-142 from said fourth composition to provide a composition comprising HCFC-142; and a sixth composition comprising HCO-1130.

6. The method of claim 1, wherein step (a) is carried out in the presence of a catalyst.

7. The method according to claim 1, wherein in the step (e), the chlorination treatment is carried out in the presence of a catalyst.

8. The method according to claim 1, wherein in step (e), the chlorination treatment is carried out in a gas phase or a liquid phase.

9. The method according to claim 1, wherein in the step (e), the reaction temperature of the chlorination treatment is 30°C or higher and 220°C or lower.

10. The method according to claim 1, wherein the pressure during the chlorination treatment in step (e) is normal pressure (0.1 MPa) to 1.0 MPa.

11. The method according to claim 1, wherein in the step (e), the total amount of 1,2-dichloro-2-fluoroethane (HCFC-141) and HCFC-142 contained in the composition containing HCO-1130 used in the chlorination treatment is 10 mass% or less.

12. The method according to claim 1, wherein in the step (e), the water content in the composition containing HCO-1130 used in the chlorination treatment is 1000 mass ppm or less.

13. The method of claim 5, wherein in step (d), HCFC-142 is separated from said fourth composition using rectification.

14. The method of claim 5, further comprising the step of recycling said fifth composition from step (c) to said step (a).

15. A process for producing 1-chloro-2,2-difluoroethane (HCFC-142) from 1,1,2-trichloroethane (HCC-140), comprising the step of chlorinating 1,2-dichloroethylene (HCO-1130), a by-product of the production of HCFC-142 from HCC-140, to produce HCC-140, which is then recycled as a raw material.

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