RATE CONSTANTS FOR THE REACTION OF HO2 WITH HO2, SO2, CO, N2O, TRANS-2-BUTENE, AND 2,3-DIMETHYL-2-BUTENE AT 300-K

Relative rate constants have been measured at 300 K and 1 atm total pressure for reactions of HO2 with HO2, SO2, CO, N2O, trans-2-butene, and 2,3-dimethyl-2-butene. The thermal decomposition of HO2NO2 was used as a source of HO2 radicals, and rate constants were measured relative to that of the HO2 + NO2 reaction. A rate constant of 3.8 × 10-12 cm3 molecule-1 s-1 (total uncertainty is a factor of 2) was measured for the HO2 disproportionation reaction; the good agreement of this value with the average literature value of ∼3 × 10-12 cm3 molecule-1 s-1 supports the validity of the present experimental techniques. Rate constant upper limits of 1 × 10-18, 2 × 10-20, and 4 × 10-18 cm3 molecule-1 s-1 were obtained for the reactions of HO2 with SO2, N2O, and trons-2-butene, respectively; these values indicate that the reactions will be of negligible atmospheric importance. Significant reaction rates were observed with CO and 2,3-dimethyl-2-butene and may correspond to HO2 rate constants as large as 2 × 10-19 and 4 × 10-17 cm3 molecule-1 s-1, respectively; these values must be regarded as only upper limits because of the possible effects of large amounts of the reactants on HO2NO2 in the gas phase or on the cell surfaces. © 1979 American Chemical Society.