8.5 g of 12,12-difluorododec-11-enoic acid chloride are added at room temperature to 3.45 g of 4-propylsulfonylaniline, 2.5 g of triethylamine and 100 mg of 4-dimethylaminopyridine in 50 ml of toluene and the mixture is stirred for 2 days at room temperature. A further 50 ml of toluene is then added, the toluene phase is washed with water, dried over sodium sulfate and concentrated to dryness by evaporation in vacuo. The residue is chromatographed on silica gel with hexane:ethyl acetate (7:3), yielding the title compound having a melting point of 67°-70° C. (compound no. 3-4).
