Examples of Catalytic and Selective Routes for Fluorinated Building Blocks

Sylvette Brunet (1)

1 IC2MP [Poitiers] - Institut de chimie des milieux et matériaux de Poitiers [UMR 7285]

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 SbCl5 in liquid phase and chromium oxide in gas phase. In the presence of SbCl5 at 90 degrees 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-trifluoromethy1-3-trichloromethylbenzene from bis-1,3-trichloromethylbenzene at low temperature (50 degrees C) and in the presence of a low amount of HF. Moreover, trichloromethoxybenzene was totally transformed into trifluoromethoxybenzene. At 380 degrees C and at atmospheric pressure, the transformation of CF3CH2Cl into CF3CH2F was favored over chromium oxide-based catalyst modified by zinc (corresponding to a (Zn/Zn + Cr) molar ratio of 0.22).

Domaines: Sciences du Vivant [q-bio]

Sylvette Brunet. Examples of Catalytic and Selective Routes for Fluorinated Building Blocks . Organic Process Research and Development, 2014, 18 (8 ), pp.1067-1071. ⟨10.1021/op5130182w⟩. ⟨hal-01299436⟩