Evidence for strongly temperature‐dependent A factors in alkane decomposition and high heats of formation for alkyl radicals

The experimental data on alkane decomposition from shock‐tube and radical buffer studies and radical combination from very‐low‐pressure pyrolysis and modulation spectroscopy are shown to be consistent. They lead to experimental A factors which decrease by factors of 10–2000 from 300° to 1100°K. Heats of formation for ethyl, isopropyl, and t‐butyl radicals have been found to be 10, 10 and 20 kJ higher than currently accepted numbers from metathesis reactions.