The gas phase reactions of benzyl radicals with O, O3, and NO3: Rate, mechanism, and unimolecular decomposition of the chemically activated benzoxy radical

Abstract

AbstractThe reactions of the benzyl radical with O, O3, and NO3 are investigated in a discharge flow‐reactor with mass spectrometric detection. For the rate coefficients of the latter two reactions, we obtain values of 2.8·1013 and 1.93·1012 cm3 mol−1s−1, respectively (T≈300 K, P ≈ 2 mbar). The main products for all three reactions are C6H6 and C6H5CHO with relative yields of 0.60/0.40 (M. Bartels, J. Edelbüttel‐Einhaus, and K. Hoyermann, 22nd Int. Symp. on Combustion, p. 1041, The Combustion Institute. Pittsburgh 1988), 0.37/0.66, and 0.23/0.77, respectively. These branching fractions are interpreted in terms of the unimolecular decomposition of an intermediarily formed benzoxy radical, using statistical rate theory. The molecular data needed are calculated by quantum chemical methods. The verification of the experimental branching fractions requires the assumption of a direct reaction channel leading from C6H5CH2O to C6H6. The nature of this channel is still uncertain.