The thermal decomposition of perfluorocyclobutane in a single-pulse shock tube

The thermal decomposition of perfluorocyclobutane was studied between 1100 and 1265°K behind reflected shock waves in a modified single-pulse shock tube using dilute c-C₄F₈-Ar mixtures. Reflected shock temperatures were evaluated from the Rankine-Hugoniot equations using measured incident and reflected shock velocities Analyses were carried out by mass spectrometry and gas chromatography. The observed reaction product was almost exclusively C₂F₄ except at the highest temperatures where small amounts of C₃F₆ were also observed The principal process involves the unimolecular decomposition, c-C₄F₈ → 2C₂F₄. The first-order high-pressure rate constant was found to be k^∞ = 10^16.0±0.6 exp[(-75,500 ± 3000)/RT]sec^-1 in good agreement with previous low temperature data obtained in a static system.