21.2 g (0.1 mol) of perfluorocyclopentene were added dropwise at 5° C. to 13 g (0.1 mol) of sodium 4-methylphenoxide in 50 ml of dimethylformamide in the course of 15 minutes. After stirring at room temperature for 8 hours, a solution of 13.9 (0.1 mol) of 4-nitrophenol and 10.1 g of triethylamine in 50 ml of dimethylformamide was added dropwise to the reaction mixture, which was stirred for a further 6 hours at 40° C. The reaction mixture was then stirred into 300 ml of water and the organic phase was separated off after addition of 100 ml of methylene chloride. The organic phase was then washed successively with 50 ml of water, 50 ml of 5% strength hydrochloric acid and again with 50 ml of water, dried over sodium sulphate and evaporated to dryness on a rotary evaporator. The crude yield of product was 34 g. It was recrystallized from petroleum ether and 20 g of crystalline material were thus obtained, which corresponds to 47.7% of theory. The crystalline material had a melting point of 72° to 76° C. and showed a value for m/e of 419 for the molecular ion in the mass spectrum.
