Formation of Perfluorobutene-2 Epoxide in the Thermal Gas-Phase Reaction of Perfluorobutene-2 with Nitrogen Dioxide. An Experimental and DFT Study

Abstract

The mechanism of the thermal reaction between perfluorobutene-2 and NO2 in the gas phase has been investigated in the temperature range 418.5–470.0K. At temperatures below 432K, equal amounts of perfluorobutene-2 epoxide (PFBE) and NO are formed. At higher temperatures, PFBE decomposes generating CF3C(O)F and CF3CF biradicals. The latter self-recombine reforming the parent perfluorobutene-2 molecule. The addition of O2 does not affect the reaction course. This reaction system provides a new and promising method for PFBE preparation. Based on the perfluorobutene-2 consumption, PFBE yields larger than 90% were obtained. The energetics of the relevant reaction pathways has been calculated using various density functional theory methods. These calculations confirm the reaction mechanism based on experimental results. The computed vibrational spectra predicted for the PFBE at the B3LYP/6-311+G(3df) and B98/6-311+G(3df) levels of theory are in very good agreement with that obtained experimentally.