Rate constants for the reactions of the NO3 radical with alkanes at 296 ± 2 K

Rate constants for the gas-phase reactions of the NO3 radical with a series of branched and straight-chain alkanes have been measured at 296 ± 2 K using a relative rate method. Using a rate constant for the reaction of the NO3 radical with 2,3-dimethylbutane of 4.08 × 10−16 cm3 molecule−1 s−1 at 296 K, the rate constants obtained (in units of 10−16 cm3 molecule−1 s−1) were: 2-methylbutane, 1.56 ± 0.16; 2-methylpentane, 1.71 ± 0.18; 3-methylpentane, 2.04 ± 0.21; 2,4-dimethylpentane, 1.44 ± 0.45; 2,2,3-trimethylbutane, 2.23 ± 0.33; 2,2,4-trimethylpentane, 0.75 ± 0.32; 2,2,3,3-tetramethylbutane, < 0.49; n-nonane, 1.92 ± 0.53; and n-decane, 2.59 ± 0.61, where the indicated error limits are two least-squares standard deviations and do not include the estimated overall uncertainties in the rate constant for the reference alkane 2,3-dimethylbutane. While the rate constants for the reactions of the NO3 radical with the n-alkanes n-butane through n-decane increase linearly with the carbon number, the rate constants for several of the branched alkanes show deviations from the expected correlation with the number of tertiary CH- groups.