Kinetics of hexafluoropropylene oxide pyrolysis studied by gas-phase NMR. Kinetic measurements made easy

Gas-phase NMR complemented with a high-temperature probe makes possible qua ntitative kinetic studies of homogeneous vapor-phase reactions with unprece dented ease, as demonstrated with a study of the thermal fragmentation of h exafluoropropylene oxide. The reaction follows strictly first-order kinetic s, is unaffected by surface chemistry, and the resulting Arrhenius activati on parameters compare well with those obtained by more laborious classical methods of gas-phase reaction kinetics. The fragmentation kinetics is also unaffected by the presence of oxygen. The profiles for the evolution of the final products in this case show very graphically that singlet difluorocar bene, one of the initial products of the fragmentation of hexafluoropropyle ne oxide, does not react with oxygen, a ground-state triplet, at chemically significant rates.