Temperature dependence of the reaction C2H (C2D) + O2 between 295 and 700 K

The rate coefficients for the reactions of C2H and C2D with O2 have been measured in the temperature range 295 K ⩽ T ⩽ 700 K. Both reactions show a slightly negative temperature dependence in this temperature range, with kC2H+O2 = (3.15 ± 0.04) × 10−11 (T/295 K)−(0.16 ± 0.02) cm3 molecule−1 s−1. The kinetic isotope effect is kC2HkC2D = 1.04 ± 0.03 and is constant with temperature to within experimental error. The temperature dependence and the C2H + O2 kinetic isotope effect are consistent with a capture-limited metathesis reaction, and suggest that formation of the initial HCCOO adduct is rate-limiting.