Temperature and pressure effects on formation and decomposition of phenylvinylperoxy radicals in the C6H5C2H2Â +Â O2 reaction

The effects of temperature and pressure on the formation and decomposition of C6H5C2H2O2 in the C6H5C2H2 + O2 reaction have been investigated at temperatures from 298 to 378 K by directly monitoring the C6H5C2H2O2 radical in the visible region by cavity ringdown spectrometry (CRDS). The rate constant for the C6H5C2H2 + O2 association and that for fragmentation of C6H5C2H2O2 were found to be k1 (C6H5C2H2 + O2 → C6H5C2H2O2) = (3.20 ± 1.19) × 1011 exp(+760/T) cm3 mol−1 s−1 and k2 (C6H5C2H2 O2 → C6H5CHO + HCO) = (1.68 ± 0.13) × 104 s−1, respectively. Additional kinetic measurements by pulsed laser photolysis/mass spectrometry show that C6H5CHO was produced in the C6H5C2H2 + O2 reaction as predicted and the formation of C6H5CHO from the decomposition of C6H5C2H2O2 is temperature-independent, consistent with the CRDS experimental data.