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

Abstract

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.