52695-47-3

Examples are presented for the catalytic fluorination of chlorinated starting materials in order to produce building blocks or HFCs. The fluorination of CF3CH2Cl, of CCl2=CCl2, of trichloromethoxylbenzenes and trichloromethoxybenzene involving nucleophilic substitution are reported. In all cases, HF was the fluorinating agent. Depending on the chlorinated substrate and the degree of fluorination required, liquid- or gas-phase processes were involved. Usually, catalysts were SbCl 5 in liquid phase and chromium oxide in gas phase. In the presence of SbCl5, at 90 °C under an initial pressure of 10 bar, the fluorination of CCl2=CCl2 leads mainly to the formation of CClF2CHCl2, and the active catalyst is an antimony mixed halide (SbCl3F2). In the same way, the presence of SbCl5 favored the formation of 1-trifluoromethyl-3- trichloromethylbenzene from bis-1,3-trichloromethylbenzene at low temperature (50 °C) and in the presence of a low amount of HF. Moreover, trichloromethoxybenzene was totally transformed into trifluoromethoxybenzene. At 380 °C and at atmospheric pressure, the transformation of CF 3CH2Cl into CF3CH2F was favored over chromium oxide-based catalyst modified by zinc (corresponding to a (Zn/Zn + Cr) molar ratio of 0.22).