Kinetics of the reactions of OH radicals with n ‐alkanes at 299 ± 2 K

Relative rate constants for the reaction of OH radicals with a series of n ‐alkanes have been determined at 299 ± 2 K, using methyl nitrite photolysis in air as a source of OH radicals. Using a rate constant for the reaction of OH radicals with n ‐butane of 2.58 × 10 −12 cm 3 molecule −1 s −1 , the rate constants obtained are (X10 12 cm 3 molecule −1 s −1 ): propane 1.22 ± 0.05, n ‐pentane 4.13 ± 0.08, n ‐heptane 7.30 ± 0.17, n ‐octane 9.01 ± 0.19, n ‐nonane 10.7 ± 0.4, and n ‐decane 11.4 ± 0.6. The data for propane, n ‐pentane, and n ‐octane are in good agreement with literature values, while those for n ‐heptane, n ‐nonane, and n ‐decane are reported for the first time. These data show that the rate constant per secondary C—H bond is ∽40% higher for —CH 2 — groups bonded to two other —CH 2 — groups than for those bonded to a —CH 2 — group and a —CH 3 group.