| Abstract: | A method is described for extrapolating existing experimental data on the reactions of OH radicals with alkanes to higher temperatures using conventional transition-state theory. Expressions are developed for the estimation of the structural properties of the activated complex necessary for calculating ΔS± and ΔH±. The vibrational frequencies and internal rotations of the activated complex are given by those of the reacting alkane or the analogous alcohol and a set of additional internal modes that is the same for all OH + alkane reactions considered. Differences between primary, secondary, and tertiary hydrogen attack are discussed, and the validity of representing the activated complexes of all OH + alkane reactions by a fixed set of vibrational frequencies and other internal modes is evaluated. Calculations are presented for the reaction of OH with CH4, C2H6, C3H8, n-C4H10, i-C4H10, c-C4H8, c-C5H10, c-C6H12, (CH3)2CHCH(CH3)2, (CH3)3CCH(CH3)2, (CH3)4C, and (CH3)3CC(CH3)3, and the results are compared with experiments. |
