Synthesis of Hexafluoropropylene Oxide from Hexafluoropropylene and Hypochlorite Using Hydrofluoroether Solvent

Abstract

Hexafluoropropylene oxide (HFPO) is a versatile fluorochemical widely used in the synthesis of various fluorinated compounds and fluorinated polymers. In this paper, we report on the successful synthesis of HFPO via the epoxidation of hexafluoropropylene (HFP) with NaOCl in a two-phase solvent system. Among the organic phase solvents tested, hydrofluoroethers such as C4F9OCH3, C4F9OC2H5, and C7F15OC2H5 showed high HFPO yields, indicating their potential to replace conventional CFCl2CF2Cl (CFC-113), which is ozone depleting and global warming chemical. When the reaction was carried out for 20 min at room temperature, the C4F9OCH3-water two-phase system produced HFPO with over 40% yield and over 70% selectivity. To optimize the reaction conditions, various reaction parameters were investigated, including the effects of NaOH and phase transition catalysts. Analysis of the by-products using 19F and 13C NMR and X-ray diffraction (XRD) showed that HFP/HFPO decomposes during oxidation to F over bar , CO2, oxalate, trifluoroacetate, etc. Density functional theory (DFT) calculations elucidated the reaction pathway of this epoxidation: with a lower E-barrier of 12.8 kcal/mol, the nucleophilic attack of OCl over bar on the beta-carbon of HFP is preferable to the alpha-carbon pathway.