Temperature and pressure Dependence of the C2H4 Yield from the Reaction C2H5 + O2

Article abstract of DOI:10.1021/j100002a039

The yield of C2H4 from the reaction (1) has been investigated as functions of temperature (260-530 K) and pressure (50-1500 Torr) at nonambient temperature using a relative rate technique.This yield has a non-Arrhenius temperature dependence, increasing slowly at a gas density of 4.9 x E18 molecules cm^-3 with an apparent activation energy of 1.1 +/- 0.25 kcal in the temperature range 250-400 K and then increasing sharply as reaction 1 becomes reversible.These results are consistent with the formation of C2H4 via rearrangement of an excited adduct (C2H5O2*) with an energy barrier less than 1.1 cal.The yield follows a P^-0.75 dependence at temperatures below 400 K.The pressure dependence becomes less pronounced at higher temperature (P^-0.32 at 529 +/- 10 K).Rate constants of the coupled mechanism for C2H4 formation developed by Wagner et al. provide reasonable agreement with these data to within the experimental error.The overall rate constant of reaction 1 was determined as a function of temperature (260-460 K) at 580 Torr relative to that of C2H5 + Cl2 -> C2H5Cl + Cl (3).No temperature dependence is observed in the range 260-380 K 1 = (8.1 +/- 0.3) x E-12 cm³ molecule^-1s^-1>.At 460 K, the rate constant decreases ca. 35percent.