KINETICS OF THE REACTIONS BETWEEN O(3P) AND 1-BUTENE FROM 335 TO 1110-K

Rate coefficients for consumption of ground-state O atoms by reaction with 1-butene have been measured by using the high-temperature photochemistry (HTP) technique. The oxygen atoms were generated by flash photolysis of either O2 or CO2 and their relative concentrations were monitored by resonance fluorescence. The data in the 335-1110 K range are well fitted by the expression k(T) = 2.7 x 10(-11) exp(-624 K/T) + 2.4 x 10(-9) exp(-5657 K/T) cm3 molecule-1 s-1 with 2-sigma precision limits of +/- 13 to +/- 27%, depending upon temperature, and corresponding 2-sigma accuracy limits of +/- 24 and +/- 34%. Good agreement exists among the rate coefficients measured here and those measured by other isolated elementary reaction techniques; we derive a combined fit expression for the 190-1110 K range of k(T) = 9.0 x 10(-12) exp(-230 K/T) + 2.2 x 10(-10) exp(-2612 K/T) cm3 molecule-1 s-1, with a suggested 2-sigma accuracy of +/- 30%. A transition-state theory calculation for the addition reaction, which had been shown to fit the data well till 490 K, is extended to 1110 K and seen to reproduce the experimental data increasingly poorly. However, a good fit is obtained when the rate coefficients for H-atom abstraction from the alkyl group in 1-butene are added to those for addition. The conclusion that the interaction between O(3P) atoms and 1-butene involves both addition and abstraction is reflected in the desirability for the double-exponential fit expressions given. Standard three-parameter fits, given in the text for the convenience of data compilers, approximate the observations well.