Synthesis of 1,2-diiodotetrafluoroethane with pyrolysis gas of waste polytetrafluoroethylene as raw material

Abstract

In the present study, waste polytetrafluoroethylene (PTFE) is recycled to generate the monomer tetrafluoroethylene by pyrolysis in vacuum condition. The reaction parameters are investigated; under 500–550 °C and 2 kPa, the yields of tetrafluoroethylene can reach 95%. Then the pyrolysis gas is applied without separation as reactant together with iodine to synthesize 1,2-diiodotetrafluoroethane, which is the key intermediate for synthesis of many fluorine-containing compounds. Under the optimal conditions, temperature 150–160 °C, pressure 12 atm and ratio of solvent to iodine 0.5–0.6, the conversion of iodine can rise up to 98%. The method of this paper uses waste polytetrafluoroethylene (PTFE) as raw material, which is environmental benign and helpful to prevent white pollution.