To an autoclave (stainless steel, volume:1L) equipped with a mixing tank and a stirrer, C4F9I which compound (1) flow rate 25mL/min, CF2=CF2 (tetrafluoroethylene) which compound (2) flow rate 0.37g/min, (C2F5COO)2 (10 and half hour life temperature: 31°C) which compound (4) flow rate 0.052 mmol/min were supplied, the mixture was prepared by mixing at stirrer. Temperature in the autoclave was 10°C, residence time of the mixture in the autoclave was 10 minutes. The molar ratio (C4F9I/CF2=CF2)of C4F9I and CF2=CF2 in the mixed solution was 41, the amount of (C2F5COO)2 with respect to C4F9I was 0.034 mol%. Only the mixture from the bottom of the autoclave was withdrawn in the absence of gas phase, the mixture was fed to the bottom of tubular reactor (Tankan-shiki, volume: 0.5L). The mixture was not seperated by gas-liquid separation, the mixture was flow towards the outlet from the inlet of the reaction tube in the tube reactor. The temperature of the reaction tube, and a 70°C, the residence time of the mixture in the tubular reactor was set to 20 minutes. The mixture containing a compound Perfluoro-1-iodohexane C6F13I was obtained.
