Kinetics and thermochemistry of the reaction of benzyl radical with O2: Investigations by discharge flow/laser induced fluorescence between 393 and 433 K

The kinetics of the reaction of the benzyl radical with molecular oxygen has been studied between 393 and 433 K. The Discharge Flow technique with detection of benzyl radicals by Laser Induced Fluorescence in their visible absorption band has been used. All experiments have been performed at ≈1 torr in helium as the buffer gas. The radical benzyl decay plots are characteristic of the approach to equilibrium between benzyl and benzylperoxy: benzyl + O2 {article}{empty}{document}.3ex {{}{_{ to.5ex{}}}}{document} benzylperoxy (k3, k−3). Thanks to a reasonable assumption concerning the standard entropy of the reaction (3) (ΔS298°=−29 cal mol−1 K−1), based on the additivity rules of Benson, the following reaction enthalpy is derived for reaction (3): ΔH298°=(−20 ± 1 kcal mol−1). This latter value is compared with a few enthalpies of other related reactions available in the literature.