Sequential phase transfer catalysis–hydrosilylation as an efficient method for the synthesis of polyfluorinated triethoxysilanes

An efficient approach to obtain of polyfluorinated triethoxysilanes H(CF2)nCH2O(CH2)3Si(OEt)3 with high yields, is presented using a sequential reactions of phase transfer catalysis and hydrosilylation. Tetrabutylammonium bromide and Speier's catalyst (200 ppm) were used as catalysts. The hydrosilylation reaction proceeds rather quickly within 1–3 h under mild conditions at room temperature. 1H NMR monitoring indicates a selective process with the formation of only the main γ-addition product. The individuality of the synthesized triethoxy(polyfluoroalkoxy)propyl silanes have been confirmed by FTIR, 1H, 13C, 19F, and 29Si NMR spectroscopy and elemental analysis. Quantum chemical calculations have shown that with a decrease in the number of electronegative fragments CF2 in the molecule, an increase in the energetic favorability of the hydrosilylation reaction is observed. The prospects for using the obtained fluorosilanes in polymer systems are discussed.