Method for preparing iodine pentafluoride

The invention discloses a method of preparing iodine pentafluoride by chemical reaction in a negative pressure container with iodine and fluorine gas as raw materials, and iodine pentafluoride as the carrier. The method includes the following steps: firstly, the iodine is put in a reactor with iodine pentafluoride liquid; the reactor is sealed and evacuated, with pressure of -0.08 to -0.06MPa; cooling water is fed to cool the product. Then fluorine gas is fed into the reactor to have chemical reaction with the iodine, so as to form the three-phase reaction of gas, liquid and solid; the pressure in the reactor is controlled to be less than -0.02MPa and the temperature is controlled to be lower than 85 DEG C. The invention has the advantages of simple process, low reaction temperature, easiness in being controlled, stable and reliable production quality, and high yield.