Kinetics of the reaction between oxygen atoms and propargyl radicals

Abstract

The kinetics of the reaction between C 3 H 3 (propargyl radical) and O( 3 P) has been studied using a heatable tubular reactor coupled to a photoionization mass spectrometer. Rate constants were determined in the temperature range 295–750 K, and information on the reaction mechanism was obtained. The reactants were generated homogeneously in the reactor by the simultaneous in situ photolysis of SO 2 (the O-atom source) and 1–3 butadiene or propargylbromide (the C 3 H 3 source). Initial conditions were chosen to yield [O] in excess, [O]/[C 3 H 3 ] o >20. The decay of C 3 H 3 was monitored in time-resolved experiments. The rate constant was found to be independent of temperature, having the value 2.3×10 −10 cm 3 molecule −1 s −1 , and also independent of density in the range used in this study, 6–12×10 16 molecule cm −3 . The reactivity of C 3 H 3 in this reaction is compared with that of other polyatomic free radicals whose reactions with atomic oxygen have been investigated.