Provided is a method for producing hexafluoro-1,3-butadiene, and the method can produce hexafluoro-1,3-butadiene at an industrially sufficient level of yield. In a reaction liquid containing a halogenated butane represented by chemical formula, CF.sub.2X.sup.1CFX.sup.2CFX.sup.3CF.sub.2X.sup.4 (X.sup.1, X.sup.2, X.sup.3, and X.sup.4 are each independently a halogen atom other than a fluorine atom), zinc, and an organic solvent, a reaction is conducted to eliminate the halogen atoms other than a fluorine atom, X.sup.1, X.sup.2, X.sup.3, and X.sup.4, from the halogenated butane, yielding hexafluoro-1,3-butadiene. During the reaction, the concentration of a zinc halide generated by the reaction, in the reaction liquid is not more than the solubility of the zinc halide in the organic solvent.

An object of the present invention is to provide a simple, low-cost, and industrial method of producing a compound having a polyene skeleton containing hydrogen and fluorine and/or chlorine. A method of producing a. halogenated diene represented by formula (1): A.sup.1A.sup.2C=CA.sup.3-CA.sup.4=CA.sup.5A.sup.6 [A.sup.1, A.sup.2, A.sup.5, and A.sup.6 are each independently hydrogen, fluorine, chlorine, a (perfluoro)alkyl group having 1 to 3 carbon atoms, or a (perfluoro)alkenyl group; A.sup.3 and A.sup.4 are each independently hydrogen, fluorine, or chlorine; at least one of A.sup.1 to A.sup.6 is hydrogen; at least one of A.sup.1 to A.sup.6 is fluorine or chlorine] comprises a step of subjecting the same or different halogenated olefin(s) represented by for (2): A.sup.7A.sup.8C=CA.sup.9X [A.sup.7 and A.sup.8 are each independently hydrogen, fluorine, chlorine, a (perfluoro)alkyl group having 1 to 3 carbon atoms, or a (perfluoro)alkenyl group; A.sup.9 is each independently hydrogen, fluorine, or chlorine; X is bromine or iodine] to a coupling reaction in the presence of a zero-valent metal.

An object of the present invention is to provide a simple, low-cost, and industrial method of producing a compound having a polyene skeleton containing hydrogen and fluorine and/or chlorine. A method of producing a. halogenated diene represented by formula (1): A.sup.1A.sup.2C=CA.sup.3-CA.sup.4=CA.sup.5A.sup.6 [A.sup.1, A.sup.2, A.sup.5, and A.sup.6 are each independently hydrogen, fluorine, chlorine, a (perfluoro)alkyl group having 1 to 3 carbon atoms, or a (perfluoro)alkenyl group; A.sup.3 and A.sup.4 are each independently hydrogen, fluorine, or chlorine; at least one of A.sup.1 to A.sup.6 is hydrogen; at least one of A.sup.1 to A.sup.6 is fluorine or chlorine] comprises a step of subjecting the same or different halogenated olefin(s) represented by for (2): A.sup.7A.sup.8C=CA.sup.9X [A.sup.7 and A.sup.8 are each independently hydrogen, fluorine, chlorine, a (perfluoro)alkyl group having 1 to 3 carbon atoms, or a (perfluoro)alkenyl group; A.sup.9 is each independently hydrogen, fluorine, or chlorine; X is bromine or iodine] to a coupling reaction in the presence of a zero-valent metal.

By subjecting a starting material composition containing hexafluorobutadiene and at least one additional compound selected from the group consisting of octafluoro-1-butene, octafluoro-2-butene, heptafluoro-1-butene, and heptafluoro-2-butene to extractive distillation in the presence of an extraction solvent to reduce the concentration of the additional compound, hexafluorobutadiene with higher purity can be obtained.

By subjecting a starting material composition containing hexafluorobutadiene and at least one additional compound selected from the group consisting of octafluoro-1-butene, octafluoro-2-butene, heptafluoro-1-butene, and heptafluoro-2-butene to extractive distillation in the presence of an extraction solvent to reduce the concentration of the additional compound, hexafluorobutadiene with higher purity can be obtained.

According to a method for producing a perfluoroalkadiene compound represented by general formula (1): CF.sub.2CF(CF.sub.2).sub.n-4CFCF.sub.2 (1), wherein n is an integer of 4 or more, the method comprising a reaction step of adding a nitrogen-containing compound to a solution of a compound represented by general formula (2): X.sup.1CF.sub.2CFX.sup.2(CF.sub.2).sub.n-4CF.sub.2X.sup.1 (2), wherein n is the same as above, X.sup.1 is the same or different and is a halogen atom other than fluorine, and X.sup.2 is a halogen atom, the perfluoroalkadiene compound can be obtained at a high yield.

According to a method for producing a perfluoroalkadiene compound represented by general formula (1): CF.sub.2CF(CF.sub.2).sub.n-4CFCF.sub.2 (1), wherein n is an integer of 4 or more, the method comprising a reaction step of adding a nitrogen-containing compound to a solution of a compound represented by general formula (2): X.sup.1CF.sub.2CFX.sup.2(CF.sub.2).sub.n-4CF.sub.2X.sup.1 (2), wherein n is the same as above, X.sup.1 is the same or different and is a halogen atom other than fluorine, and X.sup.2 is a halogen atom, the perfluoroalkadiene compound can be obtained at a high yield.

Disclosed in the present disclosure are a method and system for producing hexafluoro-1,3-butadiene. It includes: under the action of a catalyst, chlorotrifluoroethylene reacting with hydrogen gas in a first reactor to obtain a mixture, the mixture entering a rectification apparatus, trifluoroethylene obtained by rectification entering a second reactor and reacting with bromine under light to obtain 1,2-dibromo-trifluoroethane; in a third reactor pre-loaded with the 1,2-dibromo-trifluoroethane, adding the 1,2-dibromo-trifluoroethane and solid alkali, and performing reaction to obtain bromotrifluoroethylene; and adding the bromotrifluoroethylene to a fourth reactor holding with zinc powder, an initiator and an organic solvent for reaction, so as to obtain a trifluoroethenyl zinc bromide solution, performing filtration, and then adding a coupling agent for a coupling reaction, so as to obtain hexafluoro-1,3-butadiene. The present disclosure has the advantages of high safety, good in catalytic stability and high in process selectivity, and can achieve continuous production.

Disclosed in the present disclosure are a method and system for producing hexafluoro-1,3-butadiene. It includes: under the action of a catalyst, chlorotrifluoroethylene reacting with hydrogen gas in a first reactor to obtain a mixture, the mixture entering a rectification apparatus, trifluoroethylene obtained by rectification entering a second reactor and reacting with bromine under light to obtain 1,2-dibromo-trifluoroethane; in a third reactor pre-loaded with the 1,2-dibromo-trifluoroethane, adding the 1,2-dibromo-trifluoroethane and solid alkali, and performing reaction to obtain bromotrifluoroethylene; and adding the bromotrifluoroethylene to a fourth reactor holding with zinc powder, an initiator and an organic solvent for reaction, so as to obtain a trifluoroethenyl zinc bromide solution, performing filtration, and then adding a coupling agent for a coupling reaction, so as to obtain hexafluoro-1,3-butadiene. The present disclosure has the advantages of high safety, good in catalytic stability and high in process selectivity, and can achieve continuous production.

Processes for producing Z-1,1,1,4,4,4-hexafluorobut-2-ene and intermediates for producing 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.