PURPOSE: To reduce the number of processed extremely and to obtain the titled compound useful as a raw material for a polymer in high yield directly, by reacting a difluorohaloacetyl fluoride as a raw material with a halogen trapping agent under specific conditions.
CONSTITUTION: A difluorohaloacetyl fluoride shown by the formula I(X is I, Br, or Cl) is reacted with a metal, e.g., copper, silver, etc. to be used as a trapping agent preferably under substantially anhydrous conditions at -30W100°C under pressure of 0W100kg/cm2G, to give a perfluoro-3-oxa-4-pentenoyl fluoride shown by the formula III, which is useful as a raw material for a polymer having a group shown by the formula II [Z is halogen, OR1, NR2R3(R1-R3 are 1W10C organic group)] in the side chain. In a liquid phase reaction, a solvent is preferably used. The amount of the halogen trapping agent used is 0.1W10 g atom, preferably 0.5W8 g atom based on 1 mole compound shown by the formula I.
MUNAKATA SEIJI
KUMAI SEISAKU
KANEKO ISAMU
