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Relative rate experiments were used to measure ratios of rate constants as a function of temperature for the reactions of OH with propane, n-butane, n-pentane, n-hexane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, and dimethyl ether. To assure internal consistency, ratios were measured for seventeen reactant pairs among these reactants. All of the derived rate constants are based on an absolute rate constant of the OH + C2H6 reaction using k(ethane) = 1.0 × 10^-11 exp(−1094/T) cm³/molecule s. The rate constants obtained are as follows. propane:  1.29 × 10^-11 exp(−730/T), k(298 K) = 1.11 × 10^-12. n-butane:  1.68 × 10^-11 exp(−584/T), k(298 K) = 2.37 × 10^-12. n-pentane:  1.94 × 10^-11 exp(−494/T), k(298 K) = 3.70 × 10^-12. n-hexane:  2.60 × 10^-11 exp(−480/T), k(298 K) = 5.19 ×10^-12. cyclopropane:  5.15 × 10^-12 exp(−1255/T), k(298 K) = 7.64 × 10^-14. cyclobutane:  1.62 × 10^-11 exp(−611/T), k(298 K) = 2.08 × 10^-12. cyclopentane:  2.57 × 10^-11 exp(−498/T), k(298 K) = 4.83 × 10^-12. cyclohexane:  3.58 × 10^-11 exp(−500/T), k(298 K) = 6.69 × 10^-12. dimethyl ether:  1.51 × 10^-11 exp(−496/T), k(298 K) = 2.86 × 10^-12. These results are compared with previous literature data and are discussed in terms of trends in preexponential factors and activation energies. Also, rate constants and Arrhenius parameters are derived for methylene groups in the alkanes and cycloalkanes. In the low temperature regime, the present data illustrate a persistent discrepancy between absolute and relative rate measurements. The relative data show less curvature at low temperatures, and can be adequately fit with two-parameter Arrhenius expressions.

Relative rate experiments were used to measure the rate constant and temperature dependence of the reaction of OH radicals with 2-fluoropropane (HFC-281ea), using ethane, propane, and ethyl chloride as reference standards. Measurements were made using both infrared spectroscopy and gas chromatography (GC). Results from the two measurement techniques were in good agreement, with the GC data being more precise. The rate at 298 K for HFC-281ea, based on the GC experiments, was found to be 5.7 × 10^-13 cm³/(molecule s), with Arrhenius A factor = 3.06 × 10^-12 cm³/(molecule s) and E/R = 503 K. A previously described estimation technique, along with an improved method to estimate the Arrhenius parameters, is used to predict a rate constant and temperature dependence for 2-fluoropropane, which is in good agreement with the experimental value. A prediction is also made for 1-fluoropropane, for which there are no data.

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The ClO dimer is prepared by photolysis (> 300 nm, 195‐217 K) of Cl2/Cl2O or Cl2/O3mixtures or by photolysis of Cl2O alone.