Rates of OH radical reactions. XII. The reactions of OH with <i>c</i>C₃H₆, <i>c</i>C₅H₁₀, and <i>c</i>C₇H₁₄. Correlation of hydroxyl rate constants with bond dissociation energies

Abstract

Abstract Absolute rate constants for H‐atom abstraction by OH radicals from cyclopropane, cyclopentane, and cycloheptane have been determined in the gas phase at 298 K. Hydroxyl radicals were generated by flash photolysis of H 2 O vapor in the vacuum UV, and monitored by time‐resolved resonance absorption at 308.2 nm [OH( A 2 Σ + → X 2 Π)]. The rate constants in units of cm 3 mol −1 s −1 at the 95% confidence limits were as follows: k ( c C 3 H 6 ) = (3.74 ± 0.83) × 10 10 , k ( c C 5 H 10 ) = (3.12 ± 0.23) × 10 12 , k ( c C 7 H 14 ) = (7.88 ± 1.38) × 10 12 . A linear correlation was found to exist between the logarithm of the rate constant per CH bond and the corresponding bond dissociation energy for several classes of organic compounds with equivalent CH bonds. The correlation favors a value of D( c C 3 H 5 –H) = (101 ± 2) kcal mol −1 .