Kinetics of the Reactions of the Formyl Radical with Oxygen, Nitrogen Dioxide, Chlorine, and Bromine

Article abstract of DOI:10.1021/j100314a017

The gas-phase kinetics of the reactions of HCO with four molecules (O2, NO2, Cl2, and Br2) have been studied as a function of temperature in a tubular reactor coupled to a photoionization mass spectrometer.Rate constants for each reaction were determined at a minimum of five temperatures to obtain Arrhenius parameters (k=A exp(-E_a/RT)).The results obtained are as follows (the numbers in the brackets are log A/(cm³ molecule^-1 s^1-), E_a/(kJ mol^-1), and the temperature ranges covered): HCO+O2 <-10.9 (+/-0.3), 1.7(+/-1.5), 295-713 K>; HCO+NO2 <-10.6 (+/-0.3), -1.8(+/-2.0, 294-713 K>; HCO+Cl2 <-11.2 (+/-0.3), 0.3 (+/-2.0), 296-582 K>; HCO+Br2 <-10.8 (+/-0.3), -3.7 (+/-2.0), 296-669 K>.The reactivity of HCO was found to be between that of CH3 and C2H5 in the reactions of these radicals with Cl2 and Br2, which is consistent with proposed correlations of reactivity in exothermic reactions based on free-radical ionization potentials.