PURPOSE: To prepare a compound having an ω-hydro-perfluoroalkaneoxymethyl group, useful as an intermediate for production of lubricating oil, hydraulic oil and a surface active agent, etc. in high yield, by reacting an acyl fluoride with tetrafluoroethylene in acetonitrile in the presence of silver fluoride under mild conditions.

CONSTITUTION: An acyl fluoride of formula I (X is atomic group nonreactive with fluoroformyl group; Rf is 1W20C bifunctional perfluorinated group which may contain ether bond) is reacted with tetrafluoroethylene to give the titled compound of formula II (n is integer of 1W20). It is essential to carry out the reaction in acetonitrile in the presence of silver fluoride under anhydrous conditions. The amount of silver fluoride is 0.1W2mol per 1mol of the acyl fluoride, and that of acetonitrile is 1W2pts.wt. per 1pt.wt. of the acyl fluoride. The reaction temperature is 10W100°C and the blowing pressure of tetrafluoroethylene is 0W10kg/cm2G.