Rate constants for the reactions of OH with chlorinated propanes

Abstract

Absolute rate constants have been measured for the gas-phase reactions of hydroxyl radicals with a series of chlorinated propanes: 1-chloropropane (k₁), 2-chloropropane (k₂), 1,2-dichloropropane (k₃) and 1,2,3-trichloropropane (k₄). Experiments were carried out using the pulsed laser photolysis–laser induced fluorescence technique over the temperature range 233–372 K. The kinetic data obtained were used to derive the following Arrhenius expressions (in units of cm³ molecule⁻¹ s⁻¹): k₁ = (5.7 ± 1.0) × 10⁻¹² exp[ − (526 ± 53)/T], k₂ = (2.4 ± 0.6) × 10⁻¹² exp[ − (365 ± 66)/T], k₃ = (2.1 ± 0.5) × 10⁻¹² exp[ − (453 ± 76)/T] and k₄ = (1.5 ± 0.5) × 10⁻¹² exp[ − (350 ± 100)/T]. The quoted errors for the pre-exponential factor, A, and E/R are given by ΔA = 2Aσ_lnA and ΔE/R = 2σ_E/R, respectively. At room temperature, the rate constants obtained were as follows (in units of 10⁻¹³ cm³ molecule⁻¹ s⁻¹): k₁ = (9.8 ± 1.0), k₂ = (7.0 ± 0.7), k₃ = (4.6 ± 0.6) and k₄ = (4.6 ± 0.7). The results are compared with previous determinations and discussed in terms of structure–activity relationships.