Processes for producing z-1,1,1,4,4,4-hexafluorobut-2-ene and intermediates for producing the same

Abstract

To provide compositions that meet both low ozone depletion standards as well as having low global warming potentials, and to provide manufacturing processes that provide intermediates useful to produce hydrofluoroolefins and non-chlorinated hydrofluoroolefins that have low global warming potential.SOLUTION: There is provided processes for producing Z-1,1,1,4,4,4-hexafluorobut-2-ene and intermediates for producing the same. A process for producing 2-chloro-1,1,1,4,4,4-hexafluorobutane comprises contacting 1,1,2,4,4-pentachlorobuta-1,3-diene with HF in the liquid phase in the presence of a fluorination catalyst. A process for producing 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane comprises contacting 2-chloro-1,1,1,4,4,4-hexafluorobutane with a chlorine source. A process for producing 1,1,1,4,4,4-hexafluoro-2-butyne comprises contacting 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane with a base. A process for producing Z-1,1,1,4,4,4-hexafluorobut-2-ene comprises contacting 1,1,1,4,4,4-hexafluoro-2-butyne with hydrogen.SELECTED DRAWING: None

Description

[Technical field]

[0001] Disclosed herein are liquid and gas phase processes used in the production of Z-1,1,1,4,4,4-hexafluoro-2-butene and intermediates useful in its production. The disclosure further provides processes for producing 2-chloro-1,1,1,4,4,4-hexafluorobutane and 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane. [Background technology]

[0002] Over the past several decades, many industries have been working to find alternatives to ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). CFCs and HCFCs have been used in a wide range of applications, including use as refrigerants, cleaning agents, blowing agents for thermoplastic and thermoset foams, heat transfer media, gaseous dielectrics, aerosol propellants, fire extinguishing and suppression agents, power cycle working fluids, polymerization media, particulate removal fluids, carrier fluids, buffing abrasives, and displacement drying agents. In the search for alternatives to these versatile compounds, many industries have turned to the use of hydrofluorocarbons (HFCs). HFCs have zero ozone depletion potential and therefore are not affected by the phase-out under the current regulation known as the Montreal Protocol.

[0003] In addition to the problem of ozone depletion, another environmental problem for many of these applications is global warming.Therefore, there is a need for compositions that meet low ozone depletion standards and have low global warming potential.It is believed that certain hydrofluoroolefins meet both of these goals.Therefore, there is a need for intermediates that are useful for producing hydrofluoroolefins and manufacturing processes that provide non-chlorinated hydrofluoroolefins with low global warming potential.

[0004] Incorporation by Reference All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. In the case of conflict, the present application, including any definitions herein, will control. Summary of the Invention [Means for solving the problem]

[0005] The present disclosure provides processes for producing the hydrofluoroolefin Z-1,1,1,4,4,4-hexafluorobut-2-ene (Z-HFO-1336mzz or Z-1336mzz) and intermediates useful in its production.

[0006] The present disclosure provides a process for producing 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane (HCFC-336mfa), which is produced starting from 2-chloro-1,1,1,4,4,4-hexafluorobutane (HCFC-346mdf), which in turn is produced from 1,1,2,4,4-pentachlorobuta-1,3-diene (HCC-2320az).

[0007] In some embodiments, HCFC-336mfa is used in a process to produce 1,1,1,4,4,4-hexafluoro-2-butyne, the process including contacting HCFC-336mfa with a base. In some embodiments, the 1,1,1,4,4,4-hexafluoro-2-butyne is recovered and then reacted with hydrogen to form Z-1,1,1,4,4,4-hexafluoro-2-butene.

[0008] The present disclosure provides a process for producing Z-1,1,1,4,4,4-hexafluorobut-2-ene, comprising the steps of: (a) contacting 1,1,2,4,4-pentachlorobuta-1,3-diene with HF in the liquid phase in the presence of a fluorination catalyst in the liquid phase to produce a product mixture comprising 2-chloro-1,1,1,4,4,4-hexafluorobutane; and (b) contacting the 2-chloro-1,1,1,4,4,4-hexafluorobutane with a chlorine source to produce 2,2-dichloro-1,1,1,4 (c) contacting the 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane with a base to produce a product mixture comprising 1,1,1,4,4,4-hexafluoro-2-butyne; and (d) contacting the 1,1,1,4,4,4-hexafluoro-2-butyne with hydrogen to produce a product mixture comprising Z-1,1,1,4,4,4-hexafluoro-2-butene.

[0009] In some embodiments, 1,1,2,4,4-pentachlorobuta-1,3-diene (HCC-2320az, 2320az) is produced according to a process comprising the dimerization of trichloroethylene (TCE). The process for producing 2320az comprises contacting TCE in the presence of a catalyst to produce a product mixture comprising 2320az.

[0010] [ka]

[0011] In some embodiments, the dimerization of TCE is carried out in the presence of pentachloroethane (CCl3CHCl2, HCC-120), which accelerates the dimerization process.

[0012] In certain embodiments, 2320az is produced with at least 80% selectivity, and in some embodiments, the selectivity is greater than 90%, or greater than 95%, or greater than 99%, or greater than 99.5%. In certain embodiments, 2320az is recovered from the product mixture. In some embodiments, unreacted TCE is recovered and recycled.

[0013] In some embodiments, 2-chloro-1,1,1,4,4,4-hexafluorobutane (HFC-346mdf) is produced by contacting 1,1,2,4,4-pentachlorobuta-1,3-diene with hydrogen fluoride (HF) in the liquid phase in the presence of a fluorination catalyst to produce a product mixture comprising HFC-346mdf.

[0014] In the process of the disclosure, 2-chloro-1,1,1,4,4,4-hexafluorobutane is contacted with a chlorine source to produce 2,2-dichloro-1,1,1,4,4,4-hexafluoropropane (HCFC-336mfa).

[0015] [ka]

[0016] The present disclosure further provides compositions produced according to the processes disclosed herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that includes a list of elements is not necessarily limited to those elements but may also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0018] When an amount, concentration, or other value or parameter is given as either a range, a preferred range, or a list of upper and / or lower preferred values, these are to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, whether or not the ranges are separately disclosed. When a numerical range is described herein, unless otherwise indicated, the range is intended to include its endpoints, and to include all integers and fractions within the range.

[0019] By "recover" it is meant isolating the desired product sufficiently so that it is available for its intended use, useful for example as a starting material for a subsequent reaction step or, in the case of recovering Z-1,1,1,4,4,4-hexafluoro-2-butene, as a refrigerant or a foam blowing agent or a solvent or a fire extinguishing agent or an electronic gas.

[0020] The details of the recovery step depend on the compatibility of the product mixture with the reaction conditions of the subsequent reaction step. For example, if the product is produced in a reaction medium that is different or incompatible with the subsequent reaction step, the recovery step may include a step of separating the desired product from the product mixture including the reaction medium. This separation may be performed simultaneously with the contacting step when the desired product is volatile under the reaction conditions. Volatilization of the desired product may constitute separation and thereby recovery of the desired product. If the vapor contains other materials that are intended to be separated from the desired product, the desired product may be separated, for example, by selective distillation.

[0021] Recovering the desired product from the product mixture preferably includes separating the desired product from the catalyst or other components of the product mixture used or produced in the process to produce the desired product.

[0022] The present disclosure provides, inter alia, processes for producing Z-1336mzz, and intermediates for producing Z-1336mzz. Such processes can use starting materials including 1,1,2,4,4-pentachlorobuta-1,3-diene, which can be produced from trichloroethylene, one of the methods described herein.

[0023] Formation of 1,1,2,4,4-pentachlorobuta-1,3-diene (2320az) 1,1,2,4,4-Pentachlorobuta-1,3-diene (HCC-2320az or 2320az) may be produced according to the present disclosure by dimerization of trichloroethylene (TCE). In some embodiments, a process is provided for producing a product mixture comprising 2320az, the process comprising contacting TCE with a dimerization catalyst at elevated temperature.

[0024] In some embodiments, the dimerization catalyst comprises iron. The iron dimerization catalyst may comprise metallic iron from any source (including a combination of sources) and may be or include iron powder, iron wire, iron mesh, or iron shavings. The iron catalyst may also include an iron salt, such as ferric chloride or ferrous chloride (FeCl3 or FeCl2, respectively).

[0025] In some embodiments, the dimerization catalyst comprises copper. The copper dimerization catalyst may comprise metallic copper from any source (including a combination of sources), and may be, for example, copper powder or copper wire. The copper catalyst may also comprise a cuprous or cupric salt, such as cuprous chloride or cupric chloride (CuCl or CuCl2, respectively).

[0026] The process is preferably carried out in an anhydrous environment, for example, if ferric chloride is used, the ferric chloride is preferably anhydrous.

[0027] In some embodiments, the dimerization catalyst has a specific concentration relative to the moles of TCE reactant used. Thus, in some embodiments where the catalyst comprises a metallic iron catalyst, the weight ratio of Fe wire (or Fe powder) catalyst to TCE is from about 0.0001 to about 1. In other embodiments, the weight ratio of iron catalyst to TCE is from about 0.01 to about 1.

[0028] In some embodiments, the dimerization catalyst comprises ferric chloride and the weight ratio of ferric chloride to TCE is from about 0.00001 to about 1. For example, the weight ratio of ferric chloride to TCE is from about 0.00001 to about 0.002, while in other examples the weight ratio is from about 0.00005 to about 0.001. In yet other examples, the weight ratio of ferric chloride to TCE is from about 0.0001 to about 1, while in further examples the weight ratio of ferric chloride to TCE is from about 0.00015 to about 1.

[0029] In some embodiments, trichloroethylene is contacted with a dimerization catalyst and pentachloroethane. The pentachloroethane (HCC-120) accelerates the reaction to produce a product mixture that includes 2320az. In certain embodiments, the weight ratio of HCC-120 to TCE is about 0.001 to about 1. In other embodiments, the weight ratio of HCC-120 to TCE is about 0.005 to about 1.

[0030] The dimerization of TCE is carried out at an elevated temperature, for example, a temperature in the range of about 210 to about 235° C. The temperature may be greater than 200° C. The temperature may be less than 245° C.

[0031] The pressure is typically autogenous.

[0032] The contact (residence) time is typically about 0.5 to 10 hours.

[0033] In some embodiments, the conversion of TCE is at least 15%, or at least 30%, or at least 50%. In some embodiments, the selectivity to 2320az is at least 80%, or at least 85%, or at least 90%.

[0034] By-products in the dimerization reaction may include tetrachloroethane isomers, tetrachlorobutadiene isomers, hexachlorobutene isomers, trichloroethylene oligomers. The product mixture containing 2320az may further include E-1,1,2,3,4-pentachloro-1,3-butadiene or Z-1,1,2,3,4-pentachloro-1,3-butadiene. Thus, in one embodiment, there is a composition that includes 1,1,2,4,4-pentachlorobuta-1,3-diene, E-1,1,2,3,4-pentachlorobuta-1,3-diene, and Z-1,1,2,3,4-pentachlorobuta-1,3-diene.

[0035] The process may further include recovering 2320az from the product mixture prior to using the recovered 2320az as a starting material in processes to produce, for example, HCFC-346mdf, HCFC-336mfa, 1,1,1,4,4,4-hexafluoro-2-butyne, and HFO-Z-1336mzz, as described herein.

[0036] The process for recovering 2320az from the product mixture may include one or any combination of purification techniques known in the art, such as distillation. "Recovering" 2320az from a product mixture produces a product that contains at least 95%, or at least 97%, or at least 99% 2320az.

[0037] In certain embodiments, the process for producing 2320az may further include recovering trichloroethylene from the product mixture and recycling the recovered trichloroethylene to the dimerization process described herein.

[0038] In certain embodiments, the process for producing 2320az may further include recovering hexachlorobutene isomers from the product mixture and recycling the recovered hexachlorobutene isomers to the dimerization process described herein.

[0039] In certain embodiments, the process for producing 2320az may further include recovering pentachloroethane from the product mixture and recycling the recovered pentachloroethane to the dimerization process described herein.

[0040] If present, other products such as E-1,1,2,3,4-pentachloro-1,3-butadiene and Z-1,1,2,3,4-pentachloro-1,3-butadiene may also be recovered.

[0041] Formation of 2-chloro-1,1,1,4,4,4-hexafluorobutane (HCFC-346mdf) According to the process provided herein, there is provided a process that includes contacting 1,1,2,4,4-pentachlorobuta-1,3-diene (2320az) with HF in the presence of a catalyst in the liquid phase to produce a product mixture that includes HCFC-346mdf (346mdf).

[0042] Fluorination catalysts that can be used in the liquid phase process of the present invention include those derived from Lewis acid catalysts such as metal halides. The halides may be selected from fluorides, chlorides, and bromides, or combinations thereof. The metal halides may be transition metal halides or other metal halides. Transition metal chlorides include halides of titanium, zirconium, hafnium, tantalum, niobium, tin, molybdenum, tungsten, and antimony. Other suitable metal halide catalysts include boron trichloride, boron trifluoride, and arsenic trifluoride.

[0043] In some embodiments, the liquid phase fluorination can be carried out in a reaction zone that includes any reaction vessel of suitable size for the scale of the reaction. In some embodiments, the reaction zone is a reaction vessel constructed of corrosion-resistant materials. In some embodiments, these materials include nickel-based alloys such as Hastelloy®, nickel-chromium alloys available from Special Metals Corp. under the trademark Inconel® (hereinafter "Inconel®") or nickel-copper alloys available from Special Metals Corp. (New Hartford, New York) under the trademark Monel®, or vessels lined with fluoropolymers. In other embodiments, the reaction vessel can be made of other materials of construction, including stainless steel, particularly the austenitic types, and copper-clad steel.

[0044] The molar ratio of HF to 2320az, in some embodiments, is from about 1 to about 35. In other embodiments, the molar ratio of HF to 2320az is from about 1 to about 25.

[0045] In some embodiments, the fluorination process is carried out at an elevated temperature, for example, a temperature in the range of 50-160° C. In some embodiments, the temperature may be greater than 100° C. In other embodiments, the temperature may be less than 150° C.

[0046] In some embodiments, the fluorination process is carried out at a pressure ranging from 0 to 600 psi (0 to 4.1 MPa).

[0047] In some embodiments, the residence time for the fluorination reaction may be from about 1 to about 25 hours. In other embodiments, the residence time for the fluorination reaction may be from about 2 to about 10 hours. In other embodiments, the residence time for the fluorination reaction may be from 4 to about 6 hours.

[0048] In some embodiments, the product mixture including 346mdf may further include one or more of 1,2-dichloro-1,1,4,4,4-pentafluorobutane, Z-1,1,1,4,4,4-hexafluoro-2-chloro-2-butene, E-1,1,1,4,4,4-hexafluoro-2-butene, and 1,1-dichloro-2,2,4,4,4-pentafluorobutane. In one embodiment, there is a composition comprising 2-chloro-1,1,1,4,4,4-hexafluorobutane (346mdf), 1,2-dichloro-1,1,4,4,4-pentafluorobutane (345mfd), Z-1,1,1,4,4,4-hexafluoro-2-chloro-2-butene (Z-1326mxz), E-1,1,1,4,4,4-hexafluoro-2-butene (E-1336mzz), and 1,1-dichloro-2,2,4,4,4-pentafluorobutane (345mfc).

[0049] In some embodiments, the product mixture is a composition comprising 346mdf and includes 1,1,1,4,4,4-hexafluorobutane (356mff), 1,1,1-trifluoro-2-trifluoromethylbutane (356mzz), Z-1,1,1,4,4,4-hexafluoro-2-chloro-2-butene (Z-1326mxz), E-1,1,1,4,4,4-hexafluoro-2-chloro-2-butene (E-1326mxz), Z-1,1,1,4,4,4-hexafluoro-2,3-dichlorobutene (Z-1316mxx), and E-1,1,1,4,4,4-hexafluoro-2,3-dichlorobutene (E-1316mxx). In an embodiment, the product mixture containing 346mdf contains greater than 0% and less than 2% by weight of 356mff and 356mmz, respectively, greater than 0% and less than 3% by weight of Z-1326mxz, Z-1316mxx, and E-1316mxx, and greater than 0% and less than 5% by weight of E-1326mxz. This composition is useful for producing 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane (336mfa) as described herein.

[0050] In some embodiments, 346mdf is produced with greater than 90%, 92%, 94%, 95%, 96%, 97%, 98%, or 99% selectivity over other products.

[0051] The process may further include recovering 346mdf from the product mixture comprising 346mdf. Processes for recovering 346mdf include one or any combination of purification techniques known in the art, such as distillation. "Recovering" 346mdf from the product mixture produces a product comprising 346mdf that contains at least 98.5%, or at least 99, or at least 99.5% 346mdf.

[0052] In certain embodiments, the process for producing 346mdf may further include recovering 2320az from the product mixture and recycling the recovered 2320az to the fluorination process described herein.

[0053] In some embodiments, the process for producing 346mdf disclosed herein comprises the steps of: (a') contacting trichloroethylene in the presence of a dimerization catalyst to produce a product mixture comprising 2320az; and (a) contacting the 2320az produced in step (a') with hydrogen fluoride in the liquid phase in the presence of a fluorination catalyst in the liquid phase to produce a product mixture comprising 346mdf. Optionally, after step (a') and prior to step (a), 2320az is recovered.

[0054] In some embodiments, the process for producing 346mdf disclosed herein comprises the steps of: (a') contacting trichloroethylene in the presence of a dimerization catalyst and pentachloroethane to produce a product mixture comprising 2320az; and (a) contacting the 2320az produced in step (a') with hydrogen fluoride in the liquid phase in the presence of a fluorination catalyst in the liquid phase to produce a product mixture comprising 346mdf. Optionally, after step (a') and prior to step (a), 2320az is recovered.

[0055] Variations of the process elements in steps (a') and (a) are disclosed herein above. The purity of 2320az is typically at least 97% prior to proceeding to step (a).

[0056] 2. Formation of 2-dichloro-1,1,1,4,4,4-hexafluorobutane (HCFC-336mfa) The disclosure further provides a process comprising contacting 346mdf (CF3CH2CHClCF3) with a chlorine source to produce a product mixture comprising 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane (CF3CCl2CH2CF3, HCFC-336mfa, 336mfa). The process comprises chlorination, reacting a chlorine source and 346mdf to produce a product mixture comprising the desired HCFC-336mfa product. The process may be carried out in the liquid phase in a liquid medium or in the gas phase. A catalyst is optional but preferred. Alternatively, the process may use photoinitiation. An example of a liquid medium is the 346mdf reactant itself.

[0057] Examples of suitable catalysts include transition metal chlorides or Lewis acids such as aluminum chloride. Chlorination catalysts or photoinitiation may be used in liquid or gas phase processes.

[0058] The catalyst for this chlorination process in the liquid phase may be selected from ferric chloride, chromium chloride, alumina chloride, cupric chloride, and combinations of two or more of these.The catalyst for this chlorination process in the liquid phase may be selected from ferric chloride, chromium chloride, alumina chloride, cupric chloride, and combinations of two or more of these supported on carbon.

[0059] The chlorine source may be selected from chlorine, N-chlorosuccinimide, t-butyl hypochlorite, oxalyl chloride, and sulfuryl chloride.

[0060] In an embodiment, the reaction of 346mdf with a chlorine source is carried out in the presence of a chlorination catalyst and the chlorine source is chlorine. In another embodiment, the reaction of 346mdf with a chlorine source is carried out in the absence of any catalyst and the chlorine source is chlorine.

[0061] In embodiments, the reaction of 346mdf with a chlorine source is carried out in the absence of a chlorination catalyst, and the chlorine source is N-chlorosuccinimide, t-butyl hypochlorite, oxalyl chloride, and sulfuryl chloride.

[0062] The temperature and pressure conditions of the process are preferably selected to be effective to produce 336mfa with high selectivity. In carrying out the process in the liquid phase as fed by the 346mdf reactant, the process is preferably carried out in a closed pressurized reactor whose internal pressure is sufficient to maintain the 346mdf or 336mfa process product in a liquid state. The pressure in the reactor may be or may include autogenous pressure. When carrying out the process in a liquid medium, the desired product HCFC-336mfa can be recovered from the reactor by purging unreacted chlorine, distilling off unreacted HCFC-346mdf, and filtering the catalyst. When carried out in the liquid phase, the catalyst can be filtered if present in a concentration high enough to precipitate it from the product mixture before or during or after the distillation. Alternatively, the catalyst may remain in the distillation heel.

[0063] A tubular reactor may be used to carry out the process in the vapor state (phase). A chlorination catalyst may be disposed within the reactor for effective contact with the HCFC-346mdf and chlorine gas reactants which are simultaneously fed to the reactor at a temperature and residence time effective to produce the desired HCFC-336mfa reaction product at the desired selectivity. The temperature of the process is maintained by applying heat to the reactor. Preferably, the temperature of the process is in the range of 100°C to 200°C. The pressure within the tubular reactor is preferably about 0.1 to 1 MPa. The HCFC-336mfa reaction product may be recovered from the product mixture by distillation.

[0064] The chlorination of HCFC-346mdf preferably provides a selectivity to HCFC-336mfa of at least 85%, more preferably at least 90%, and most preferably at least 95%, regardless of whether the reaction is carried out in the liquid or gas phase.

[0065] Preparation of 1,1,1,4,4,4-hexafluoro-2-butyne The disclosure further provides a process comprising the step of contacting HCFC-336mfa with a base in a dehydrochlorination reaction to produce a product mixture comprising 1,1,1,4,4,4-hexafluoro-2-butyne (CF3C≡CCF3). The base is preferably a basic aqueous medium. This reaction step is preferably carried out in the presence of a catalyst. Preferably, the basic aqueous medium comprises an aqueous solution of an alkali metal hydroxide or alkali metal halide salt or other base. Preferably, the catalyst is a phase transfer catalyst. As used herein, phase transfer catalyst is intended to mean a material that promotes the transfer of ionic compounds between an organic phase and an aqueous phase. In this step, the organic phase comprises the HCFC-336mfa reactants and the aqueous phase comprises the basic aqueous medium. The phase transfer catalyst promotes the reaction of these dissimilar and incompatible components.

[0066] Different phase transfer catalysts may function in different ways, but their mechanism of action does not limit their usefulness in the present invention, so long as the phase transfer catalyst promotes the dehydrochlorination reaction.

[0067] Preferred phase transfer catalysts are quaternary alkyl ammonium salts. In some embodiments, at least one alkyl group of the quaternary alkyl ammonium salt contains at least 8 carbons. Examples of quaternary alkyl ammonium salts in which three alkyl groups contain at least 8 carbon atoms include trioctylmethylammonium chloride. Aliquat® 336 is a commercially available phase transfer catalyst containing trioctylmethylammonium chloride. Examples of quaternary alkyl ammonium salts in which four alkyl groups contain at least 8 carbon atoms include tetraoctylammonium salts. The anion of such salts can be a halide such as chloride or bromide, hydrogen sulfate, or any other commonly used anion. Specific quaternary alkyl ammonium salts include tetraoctylammonium chloride, tetraoctylammonium hydrogen sulfate, tetraoctylammonium bromide, methyltrioctylammonium chloride, methyltrioctylammonium bromide, tetradecylammonium chloride, tetradecylammonium bromide, and tetradodecylammonium chloride. According to such embodiments, the phase transfer catalyst and reaction conditions are preferably effective to achieve at least 50% conversion of HCFC-336mfa per hour.

[0068] In other embodiments, the alkyl group of the quaternary alkyl ammonium salt contains 4-10 carbon atoms, and a non-ionic surfactant is present in the aqueous basic medium. According to such embodiments, the phase transfer catalyst and reaction conditions are preferably effective to achieve at least 20% conversion of HCFC-336mfa per hour. The anion of the quaternary alkyl ammonium salt, whose alkyl group contains 4-10 carbon atoms, may be a halide, such as chloride or bromide, hydrogen sulfate, or any other commonly used anion. The above quaternary alkyl ammonium salts may be used in this embodiment, provided that their alkyl groups contain 4-10 carbon atoms. Specific additional salts include tetrabutylammonium chloride, tetrabutylammonium bromide, and tetrabutylammonium hydrogen sulfate.

[0069] Preferred nonionic surfactants include ethoxylated nonylphenol or ethoxylated C 12 ~C 15 and straight chain fatty alcohols.Nonionic surfactants useful in the present invention include Bio-soft® N25-9 and Makon® 10, available from Stepan Company (Northfield, IL).

[0070] In some embodiments, the quaternary alkyl ammonium salt is added in an amount of 0.5 mole percent to 2 mole percent of the HCFC-336mfa. In other embodiments, the quaternary alkyl ammonium salt is added in an amount of 1 mole percent to 2 mole percent of the HCFC-336mfa. In still other embodiments, the quaternary alkyl ammonium salt is added in an amount of 1 mole percent to 1.5 mole percent of the HCFC-336mfa. In some embodiments, the quaternary alkyl ammonium salt is added in an amount of 1 mole percent to 1.5 mole percent of the HCFC-336mfa, and the weight of the nonionic surfactant added is 1 to 2 times the weight of the quaternary alkyl ammonium salt. These amounts apply to each of the above embodiments of the quaternary alkyl ammonium salt used.

[0071] In some embodiments, the reaction is carried out at a temperature of about 60-90°C, most preferably 70°C.

[0072] A basic aqueous medium is a liquid (whether a solution, dispersion, emulsion, suspension, etc.) that is primarily an aqueous liquid with a pH greater than 7. In some embodiments, the basic aqueous solution has a pH greater than 8. In some embodiments, the basic aqueous solution has a pH greater than 10. In some embodiments, the basic aqueous solution has a pH between 10 and 13. In some embodiments, the basic aqueous solution contains a small amount of an organic liquid that may be miscible or immiscible with water. In some embodiments, the liquid in the basic aqueous solution is at least 90% water. In some embodiments, the water is tap water, and in other embodiments, the water is deionized or distilled water.

[0073] The base is selected from hydroxides, oxides, carbonates, or phosphates of alkali metals, alkaline earth metals, and mixtures thereof, hi some embodiments, the base is selected from lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium oxide, calcium oxide, sodium carbonate, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, and mixtures thereof.

[0074] These embodiments of the basic aqueous medium and base apply to all of the phase transfer catalysts, amounts, and reaction conditions described above. The selectivity for the formation of 1,1,1,4,4,4-hexafluoro-2-butyne is preferably at least 85%.

[0075] In some embodiments, the dehydrochlorination reaction of 336 mfa to 1,1,1,4,4,4-hexafluoro-2-butyne is carried out in the presence of an alkali metal halide salt. The alkali metal may be sodium or potassium. The halide may be chloride or bromide. A preferred alkali metal halide salt is sodium chloride. Without being bound to any particular theory, it is believed that the alkali metal halide salt stabilizes the phase transfer catalyst. Although the dehydrochlorination reaction itself produces an alkali metal chloride, particularly sodium chloride when sodium hydroxide is used as the base, the addition of additional sodium chloride has the added benefit of increasing the yield of 1,1,1,4,4,4-hexafluoro-2-butyne. In some embodiments, the alkali metal halide is added at about 25 to about 100 equivalents per mole of phase transfer catalyst. In other embodiments, the alkali metal halide is added at about 30 to about 75 equivalents per mole of phase transfer catalyst. In yet another embodiment, the alkali metal halide is added at about 40 to about 60 equivalents per mole of phase transfer catalyst. These amounts apply to each of the quaternary alkyl ammonium salts listed above.

[0076] The product 1,1,1,4,4,4-hexafluoro-2-butyne (boiling point -25°C) can be recovered from the product mixture by distillation, where the butyne can be evaporated from the aqueous medium and then condensed. Additionally, the product mixture may also contain 1,1,1,4,4,4-hexafluoro-2-chloro-2-butene (HCFO-1326, Z isomer, E isomer, or mixtures thereof), which can be separated from the product mixture and recycled to process steps including contacting HCFC-336mfa with a base in a dehydrochlorination reaction to produce a product mixture containing CF3C≡CCF3.

[0077] Preparation of Z-1,1,1,4,4,4-hexafluoro-2-butene The present disclosure further provides a hydrogenation process comprising contacting 1,1,1,4,4,4-hexafluoro-2-butyne with hydrogen to produce a product mixture comprising Z-1,1,1,4,4,4-hexafluoro-2-butene (Z-1336mzz), preferably carried out in the presence of an alkyne-alkene catalyst.

[0078] In some embodiments, the hydrogenation of 1,1,1,4,4,4-hexafluoro-2-butyne is carried out as a batch process in the liquid phase.

[0079] In some embodiments, the hydrogenation of 1,1,1,4,4,4-hexafluoro-2-butyne is carried out as a continuous process in the gas phase.

[0080] In some embodiments, the alkyne-alkene catalyst is a palladium catalyst, such as palladium dispersed on aluminum oxide or titanium silicate doped with silver and / or lanthanides. The loading of the palladium dispersed on the aluminum oxide or titanium silicate is relatively low. In some embodiments, the palladium loading is from about 100 ppm to about 5000 ppm. In other embodiments, the palladium loading is from about 200 ppm to about 5000 ppm. In some embodiments, the palladium catalyst is doped with at least one of silver, cerium, or lanthanum. In some embodiments, the molar ratio of cerium or lanthanum to palladium is from about 2:1 to about 3:1. In some embodiments, the molar ratio of silver to palladium is about 0.5:1.0.

[0081] Another embodiment of the alkyne-alkane catalyst is Lindlar's catalyst, which is a heterogeneous palladium catalyst supported on a calcium carbonate support that has been deactivated or conditioned with a lead compound. The lead compound can be lead acetate, lead oxide, or any other suitable lead compound. In some embodiments, the catalyst is produced by reducing a palladium salt in the presence of a slurry of calcium carbonate, followed by the addition of a lead compound. In some embodiments, the palladium salt in palladium chloride.

[0082] In other embodiments, the Lindlar catalyst is further deactivated or conditioned with quinoline. The amount of palladium supported on the support is typically about 5% by weight, but can be any catalytically effective amount. In other embodiments, the amount of palladium supported on the support in the Lindlar catalyst is greater than 5% by weight. In yet other embodiments, the amount of palladium supported on the support can be from about 5% by weight to about 1% by weight.

[0083] In some embodiments, the amount of catalyst used is from about 0.5% to about 4% by weight of the amount of 1,1,1,4,4,4-hexafluoro-2-butyne. In other embodiments, the amount of catalyst used is from about 1% to about 3% by weight of the amount of butyne. In yet other embodiments, the amount of catalyst used is from about 1% to about 2% by weight of the amount of butyne.

[0084] In some embodiments, the reaction step is a batch reaction and is carried out in the presence of a solvent. In one such embodiment, the solvent is an alcohol. Exemplary alcohol solvents include ethanol, i-propanol, and n-propanol. In other embodiments, the solvent is a fluorocarbon or hydrofluorocarbon. Exemplary fluorocarbons or hydrofluorocarbons include 1,1,1,2,2,3,4,5,5,5-decafluoropentane and 1,1,2,2,3,3,4-heptafluorocyclopentane.

[0085] In some embodiments, the reaction of 1,1,1,4,4,4-hexafluoro-2-butyne with hydrogen is preferably carried out by adding hydrogen in small increments, with each addition increasing the pressure in the vessel by no more than about 100 psi (0.69 MPa). In other embodiments, the addition of hydrogen is controlled such that each addition increases the pressure in the vessel by no more than about 50 psi (0.35 MPa). In some embodiments, hydrogen can be added in larger increments to the residue of the reaction after sufficient hydrogen has been consumed in the hydrogenation reaction to convert at least 50% of the butyne to Z-1336mzz. In other embodiments, hydrogen can be added in larger increments to the residue of the reaction after sufficient hydrogen has been consumed in the hydrogenation reaction to convert at least 60% of the butyne to the desired butene. In yet other embodiments, hydrogen can be added in larger increments to the residue of the reaction after sufficient hydrogen has been consumed in the hydrogenation reaction to convert at least 70% of the butyne to the desired butene. In some embodiments, the larger increment of hydrogen loading may be 300 psi (2.07 MPa), while in other embodiments, the larger increment of hydrogen loading may be 400 psi (2.76 MPa).

[0086] In some embodiments, the molar ratio is about 1 mole of hydrogen to about 1 mole of 1,1,1,4,4,4-hexafluoro-2-butyne. In other embodiments, the molar ratio of hydrogen to butyne is about 0.9 moles to about 1.3 moles. In yet other embodiments, the amount of hydrogen added is about 0.95 moles of hydrogen to about 1.1 moles of butyne. In yet other embodiments, the amount of hydrogen added is about 0.95 moles of hydrogen to about 1.03 moles of butyne.

[0087] In some embodiments, the hydrogenation is carried out at ambient temperature (15° C. to 25° C.). In other embodiments, the hydrogenation is carried out at a temperature greater than ambient temperature. In yet other embodiments, the hydrogenation is carried out at a temperature less than ambient temperature. In yet other embodiments, the hydrogenation is carried out at a temperature less than about 0° C.

[0088] In an embodiment of a continuous process, a mixture of 1,1,1,4,4,4-hexafluoro-2-butyne and hydrogen is passed through a reaction zone containing a catalyst. A reaction vessel, such as a metal tube, may be used and packed with catalyst to form the reaction zone. In some embodiments, the molar ratio of hydrogen to butyne is about 1:1. In other embodiments of a continuous process, the molar ratio of hydrogen to butyne is less than 1:1. In yet other embodiments, the molar ratio of hydrogen to butyne is about 0.67:1.0.

[0089] In some embodiments of the continuous process, the reaction zone is maintained at ambient temperature. In another embodiment of the continuous process, the reaction zone is maintained at a temperature of 30° C. In yet another embodiment of the continuous process, the reaction zone is maintained at a temperature of about 40° C.

[0090] In some embodiments of the continuous process, the flow rates of 1,1,1,4,4,4-hexafluoro-2-butyne and hydrogen are maintained such that the residence time in the reaction zone is about 30 seconds. In other embodiments of the continuous process, the flow rates of butyne and hydrogen are maintained such that the residence time in the reaction zone is about 15 seconds. In yet other embodiments of the continuous process, the flow rates of butyne and hydrogen are maintained such that the residence time in the reaction zone is about 7 seconds.

[0091] It is understood that by increasing the flow rate of 1,1,1,4,4,4-hexafluoro-2-butyne and hydrogen entering the reaction zone, the residence time in the reaction zone is reduced. As the flow rate increases, the amount of butyne hydrogenated per unit time increases. Since hydrogenation is exothermic, depending on the length and diameter of the reaction zone and its heat dissipation capacity, at higher flow rates it may be desirable to provide an external cooling source in the reaction zone to maintain the desired temperature.

[0092] The contacting step conditions, including the selection of the catalyst, are preferably selected to produce Z-1336mzz with a selectivity of at least 85%, more preferably at least 90%, and most preferably at least 95%.

[0093] In some embodiments, upon completion of the batch or continuous isomerization process, Z-1336mzz can be recovered through any conventional process, including, for example, fractionation. Unconverted hexafluoro-2-butyne may be recovered and recycled to the hydrogenation process. In other embodiments, upon completion of the batch or continuous hydrogenation process, Z-1336mzz has sufficient purity such that no further purification steps are required. EXAMPLES

[0094] material Trichloroethylene, ferric chloride, pentachloroethane (HCC-120), chlorine, TaCl5, and tetra-n-butylammonium bromide (TBAB), and trioctylmethylammonium chloride (Aliquat® 336) are available from Sigma Aldrich (St. Louis, MO). Hydrogen fluoride was purchased from Synquest Labs, Inc. (Alachua, FL). Makon® 10 non-ionic surfactant is available from Stepan Company (Northfield, IL).

[0095] GC analyses of Examples 1-4 were carried out using an Agilent® 5975 GC, RESTEK Rtx-1 column.

[0096] Example 1: Preparation of 1,1,2,4,4-pentachlorobuta-1,3-diene (HCC-2320az) Trichloroethylene (100 g, 0.76 mol) was added to a shaker tube containing 30 mg of anhydrous FeCl. The reaction mixture was heated at 230° C. for 2 h. The reactor contents were cooled to room temperature and analyzed by GC to determine conversion and selectivity. The results are provided in Table 1.

[0097] Example 2: Preparation of 1,1,2,4,4-pentachlorobuta-1,3-diene (HCC-2320az) Trichloroethylene (100 g, 0.76 mol) was added to a shaker tube containing 1 g of iron wire. The reaction mixture was heated at 230° C. for 2 hours. The reactor contents were cooled to room temperature and analyzed by GC to determine conversion and selectivity. The results are provided in Table 1.

[0098] Example 3: Preparation of 1,1,2,4,4-pentachlorobuta-1,3-diene (HCC-2320az) Trichloroethylene (100 g, 0.76 mol) was added to a shaker tube containing 20 mg of anhydrous FeCl3 and 1 g of HCC-120. The reaction mixture was heated at 230° C. for 2 hours. The reactor contents were cooled to room temperature and analyzed by GC to determine conversion and selectivity. The results are provided in Table 1.

[0099] Example 4: Preparation of 1,1,2,4,4-pentachlorobuta-1,3-diene (HCC-2320az) Trichloroethylene (100 g, 0.76 mol) was added to a shaker tube containing 1 g of iron wire and 1 g of HCC-120. The reaction mixture was heated at 230° C. for 2 hours. The reactor contents were cooled to room temperature and analyzed by GC to determine conversion and selectivity. The results are provided in Table 1.

[0100] [Table 1]

[0101] As can be seen from Table 1, the presence of HCC-120 increases the conversion of trichloroethylene to 2320az when FeCl3 or Fe wire catalyst is used.

[0102] Example 5: Preparation of 2-chloro-1,1,1,4,4,4-hexafluorobutane (HCFC-346mdf) TaCl5 (12.5 g) was added to a 210 mL Hastelloy C reactor followed by HF (49 g). The reaction mixture was heated to 150° C. for 1 h and cooled to 0° C. HCC-2320az (26 g) was added to the reactor and the reaction was reheated to 130° C. The reaction rate was indicated by the pressure increase. Level-off pressure indicates completion of the reaction. After aqueous workup and phase separation, the product mixture was analyzed by GC which showed 100% conversion of starting material and 98% selectivity to product HCFC-346mdf.

[0103] Example 6: Preparation of 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane (HCFC-336mfa) A Hastelloy tube (½ inch OD) with a 12″ heated reaction zone is used in the following reaction. The reaction zone is preheated to 300° C. HCFC-346mdf is fed at 3.1 sccm (5.2×10 -8 m 3 / sec), and chlorine gas was supplied at 11.6 sccm (1.9 × 10 -7 m 3 / sec). No catalyst is present. A portion of the reactor effluent is passed through a series of valves and analyzed by GCMS. After 13 hours of continuous operation, the product contains 90% 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane (HCFC-336mfa).

[0104] Example 7: Preparation of 1,1,1,4,4,4-hexafluoro-2-butyne Example 7 demonstrates the conversion of HCFC-336mfa to 1,1,1,4,4,4-hexafluoro-2-butyne in the presence of Aliquat® 336 quaternary ammonium salt.

[0105] Aqueous NaOH (22 mL, 0.22 mol) is added to HCFC-336mfa (23.5 g, 0.1 mol) and water (5.6 mL) in the presence of Aliquat® 336 ammonium salt (0.53 g, 0.001325 mol) at room temperature. After addition, the reaction temperature is increased to 70° C. and the reaction is monitored using gas chromatography. The reaction is complete after 2 hours and 1,1,1,4,4,4-hexafluorobutyne is collected in a dry ice trap.

[0106] Example 8: Preparation of 1,1,1,4,4,4-hexafluoro-2-butyne Example 8 demonstrates the conversion of HCFC-336mfa to 1,1,1,4,4,4-hexafluoro-2-butyne in the presence of tetrabutylammonium bromide and a non-ionic surfactant.

[0107] Aqueous NaOH (22 mL, 0.22 mol) is added to HCFC-336mfa (23.5 g, 0.1 mol) and water (5.6 mL) in the presence of tetrabutylammonium bromide (0.45 g, 0.001325 mol) and Makon® 10 non-ionic surfactant (0.7 g) at room temperature. After addition, the reaction temperature is increased to 70° C. and the reaction is monitored using gas chromatography. The reaction is complete after 4.5 hours and 1,1,1,4,4,4-hexafluorobutyne is collected in a dry ice trap.

[0108] Example 9: Preparation of Z-1,1,1,4,4,4-hexafluoro-2-butene 1,1,1,4,4,4-Hexafluoro-2-butyne was reacted with hydrogen to produce the desired Z isomer of 1,1,1,4,4,4-hexafluoro-2-butene by the following procedure: 5 g of Lindlar (5% Pd on lead-poisoned CaCO3) catalyst was charged to a 1.3 L rocker bomb. 480 g (2.96 mol) of hexafluoro-2-butyne was charged to the rocker. The reactor was cooled (-78°C) and evacuated. After warming the bomb to room temperature, H2 was added slowly in increments not exceeding Δp = 50 psi (0.35 MPa). A total of 3 moles of H2 was added to the reactor. Gas chromatographic analysis of the crude product showed that the mixture consisted of CF3C≡CCF3 (0.236%), the trans isomer of E-CF3CH=CHCF3 (0.444%), saturated CF3CH2CH2CF3 (1.9%) CF2=CHCl, an impurity derived from the starting butyne (0.628%), and the cis isomer Z-CF3CH=CHCF3 (96.748%).

[0109] Distillation of the crude product gave 287 g (59% yield) of 100% pure cisCF3CH=CHCF3 (bp 33.3 °C). MS: 164 [MI], 145 [M-19], 95 [CF3CH=CH], 69 [CF3]. NMR H 1 : 6.12 ppm (multiplet), F 19 : -60.9 ppm (triplet J = 0.86 Hz). The selectivity of this reaction towards the formation of the Z isomer was 96.98%. The Z isomer was recovered by distillation.

[0110] Other embodiments 1. In some embodiments, the disclosure provides a process for preparing 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane, comprising contacting 2-chloro-1,1,1,4,4,4-hexafluorobutane with a chlorine source. 2. In some embodiments, 2-chloro-1,1,1,4,4,4-hexafluorobutane is produced by contacting 1,1,2,4,4-pentachlorobuta-1,3-diene with HF in the liquid phase in the presence of a fluorination catalyst. 3. In some embodiments, 1,1,2,4,4-pentachlorobuta-1,3-diene is produced by contacting trichloroethylene in the presence of a dimerization catalyst. 4. The process of any one of embodiments 1, 2, or 3, further comprising contacting 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane with a basic aqueous medium to produce a product comprising 1,1,1,4,4,4-hexafluoro-2-butyne. 5. Any one of the embodiments described in embodiment 4, further comprising contacting 1,1,1,4,4,4-hexafluoro-2-butyne with hydrogen to produce a product comprising Z-1,1,1,4,4,4-hexafluoro-2-butene. 6. Any one of the embodiments described in embodiment 1, 2, 3, 4, or 5, further comprising recovering 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane. 7. Any one of the embodiments described in embodiment 2, 3, 4, 5, or 6, further comprising recovering 2-chloro-1,1,1,4,4,4-hexafluorobutane. 8. Any one of the embodiments described in embodiment 3, 4, 5, 6, or 7, further comprising recovering 1,1,2,4,4-pentachlorobuta-1,3-diene. 9. Any one of the embodiments described in embodiment 4, 5, 6, 7, or 8, further comprising recovering the 1,1,1,4,4,4-hexafluoro-2-butyne. 10. Any one of the embodiments described in embodiment 5, 6, 7, 8, or 9, further comprising recovering Z-1,1,1,4,4,4-hexafluoro-2-butene. 11. In some embodiments, the process for producing Z-1,1,1,4,4,4-hexafluoro-2-butene comprises: (a) contacting 1,1,2,4,4-pentachlorobuta-1,3-diene with HF in the liquid phase in the presence of a fluorination catalyst in the liquid phase to produce a product mixture comprising 2-chloro-1,1,1,4,4,4-hexafluorobutane; (b) contacting 2-chloro-1,1,1,4,4,4-hexafluorobutane with chlorine to produce a product mixture comprising 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane; (c) contacting 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane with a base to produce a product mixture comprising 1,1,1,4,4,4-hexafluoro-2-butyne; (d) contacting the 1,1,1,4,4,4-hexafluoro-2-butyne with hydrogen to produce a product mixture comprising Z-1,1,1,4,4,4-hexafluoro-2-butene. 12. In some embodiments, the chlorine source according to embodiment 1 is chlorine. 13. In some embodiments, the catalyst of embodiment 2 comprises a metal halide. 14. Embodiment 2, wherein 1,1,2,4,4-pentachlorobuta-1,3-diene is produced by contacting trichloroethylene in the presence of a dimerization catalyst and pentachloroethane. 15. Any one of the embodiments described in embodiment 1, 2, or 3, further comprising contacting 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane with a basic aqueous medium and a phase transfer catalyst to produce a product comprising 1,1,1,4,4,4-hexafluoro-2-butyne. 16. Embodiment 5, wherein 1,1,1,4,4,4-hexafluoro-2-butyne is contacted with hydrogen in the presence of an alkyne-alkene catalyst to produce a product comprising Z-1,1,1,4,4,4-hexafluoro-2-butene. 17. Embodiment 16, wherein the alkyne-alkene catalyst is a palladium catalyst dispersed on aluminum oxide, silicon carbide, or titanium silicate with Ag or a lanthanide poison at a concentration of 100-5000 ppm. 18. Embodiment 1, wherein the chlorine source is Cl2 and the process is carried out in the absence of a catalyst.

[0111] Although the present invention has been described in conjunction with its detailed description, it should be understood that the foregoing description is intended to illustrate and not to limit the scope of the invention as defined by the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims. It should be understood by those skilled in the art that the present invention can be combined with any of the features described herein with respect to any particular aspect and / or embodiment of the invention, with any one or more of the other features of any other aspect and / or embodiment of the invention described herein, with appropriate modifications to ensure compatibility of the combination. Such combinations are considered to be part of the invention contemplated by this disclosure.

Claims

[Claim 1] A process for producing 2,2-dichloro-1,1,1,4,4,4-hexafluorobutane, comprising the step of contacting 2-chloro-1,1,1,4,4,4-hexafluorobutane with a chlorine source.

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