Fluorotrimethylsilane → 2-Bromo-2-(trifluoromethyl)hexafluoropropane

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Reaction Steps

Bromine, 17.25 g (0.108 mol), was added dropwise at 0° to a solution of tris(dimethylamino)sulfonium 1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)-2-propanide, prepared by dissolving 33.4 g (0.12 mol) of tri(dimethylamino)sulfonium difluorotrimethylsilicate and 24.0 g (0.12 mol) of perfluoroisobutylene in 75 mL of benzonitrile, then pumping out the by-product fluorotrimethylsilane at reduced pressure. The reaction mixture was evacuated to transfer the volatile reaction product into a cold trap (-78°). Sublimation of the contents of the trap at atmospheric pressure gave 26.11 g (81%) of 2-bromo-1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)propane as a very volatile solid: m.p. (sublimation 49°-51°; 19F NMR (CDCl3) δ -67.6 ppm (s).

Provenance & Evidence