A method for the synthesis of two-dimensional (2D) bismuth (bismuthene) and a use of this material as a photoredox catalyst are provided. The 2D bismuthene is prepared by a liquid-phase exfoliation of the 3D-layered bismuth. The photoredox catalyst is used for the C-H functionalization reactions for the synthesis of complex molecules under versatile conditions.

A synthesis method for hexafluorobutadiene is provided. In the synthesis method, a fluoride having saturated chemical bonds and having a purity 99.5% and a boiling point 120 C. as a stabilizer is uniformly mixed with chlorotrifluoroethylene and then heated for a dimerization reaction. Under the effect of the above stabilizer, the heat during the reaction can be homogenized without causing local temperature to increase easily, the flow rate of raw materials will be more stable, the occurrence of side reactions due to temperature fluctuations will be reduced, and the conversion rate of chlorotrifluoroethylene and the yield of intermediate dimer will be improved. In the method, the stabilizer and the unreacted raw materials can be separated and recycled, such that, comprehensively, the conversion rate of the chlorotrifluoroethylene can be up to 95% or higher, and the yield of the intermediate dimer can be 95% or higher.

A synthesis method for hexafluorobutadiene is provided. In the synthesis method, a fluoride having saturated chemical bonds and having a purity 99.5% and a boiling point 120 C. as a stabilizer is uniformly mixed with chlorotrifluoroethylene and then heated for a dimerization reaction. Under the effect of the above stabilizer, the heat during the reaction can be homogenized without causing local temperature to increase easily, the flow rate of raw materials will be more stable, the occurrence of side reactions due to temperature fluctuations will be reduced, and the conversion rate of chlorotrifluoroethylene and the yield of intermediate dimer will be improved. In the method, the stabilizer and the unreacted raw materials can be separated and recycled, such that, comprehensively, the conversion rate of the chlorotrifluoroethylene can be up to 95% or higher, and the yield of the intermediate dimer can be 95% or higher.

There is provided a method for producing chlorofluorobutane (CFB) by forming chlorinated butadiene by dimerizing trichloroethylene (TCE) and fluorinating hydrogen atoms of the chlorinated butadiene. Trichloroethylene (TCE) is dimerized by using a dimer represented by the following formula (1) as a solvent and in the presence of a free radical generating agent at a temperature of 100 C. or higher. Hexachlorobutadiene (C.sub.4Cl.sub.6) is produced from the above dimer by chlorination and dehydrochlorination reaction, and further, the chlorofluorobutane (CFB) is produced by fluorinating the hexachlorobutadiene.

##STR00001##

There is provided a method for producing chlorofluorobutane (CFB) by forming chlorinated butadiene by dimerizing trichloroethylene (TCE) and fluorinating hydrogen atoms of the chlorinated butadiene. Trichloroethylene (TCE) is dimerized by using a dimer represented by the following formula (1) as a solvent and in the presence of a free radical generating agent at a temperature of 100 C. or higher. Hexachlorobutadiene (C.sub.4Cl.sub.6) is produced from the above dimer by chlorination and dehydrochlorination reaction, and further, the chlorofluorobutane (CFB) is produced by fluorinating the hexachlorobutadiene.

##STR00001##

There is provided a method for producing chlorofluorobutane (CFB) by forming chlorinated butadiene by dimerizing trichloroethylene (TCE) and fluorinating hydrogen atoms of the chlorinated butadiene. Trichloroethylene (TCE) is dimerized by using a dimer represented by the following formula (1) as a solvent and in the presence of a free radical generating agent at a temperature of 100 C. or higher. Hexachlorobutadiene (C.sub.4Cl.sub.6) is produced from the above dimer by chlorination and dehydrochlorination reaction, and further, the chlorofluorobutane (CFB) is produced by fluorinating the hexachlorobutadiene.

##STR00001##

A process for producing E-1,1,1,4,4,4-hexafluorobut-2-ene comprises contacting 1,1,2,4,4-pentachlorobuta-1,3-diene with hydrogen fluoride in the vapor phase in the presence of a fluorination catalyst. A process for producing Z-1,1,1,4,4,4-hexafluorobut-2-ene further comprises contacting E-1,1,1,4,4,4-hexafluoro-2-butene with chlorine in the presence of a catalyst to produce 2,3-dichloro-1,1,1,4,4,4-hexafluorobutane, followed by reaction with base to produce 1,1,1,4,4,4-hexafluoro-2-butyne, and subsequently hydrogenating hexafluoro-2-butyne to produce Z-1,1,1,4,4,4-hexafluoro-2-butene.

A process for producing E-1,1,1,4,4,4-hexafluorobut-2-ene comprises contacting 1,1,2,4,4-pentachlorobuta-1,3-diene with hydrogen fluoride in the vapor phase in the presence of a fluorination catalyst. A process for producing Z-1,1,1,4,4,4-hexafluorobut-2-ene further comprises contacting E-1,1,1,4,4,4-hexafluoro-2-butene with chlorine in the presence of a catalyst to produce 2,3-dichloro-1,1,1,4,4,4-hexafluorobutane, followed by reaction with base to produce 1,1,1,4,4,4-hexafluoro-2-butyne, and subsequently hydrogenating hexafluoro-2-butyne to produce Z-1,1,1,4,4,4-hexafluoro-2-butene.