Absolute rate constants and Arrhenius parameters for the reaction of bromine atoms with ethane

The direct thermal bromination of C2H6 has been studied spectrophotometrically in a static system over the temperature range 221–319°C. The kinetics agree with the mechanism, Br2⇌ 2Br· [graphic ommitted]. From measurements of initial rates, log 10(k1/1. mol–1s–1)=(11.6±0.10)–(14.0±0.25)/θ, where θ= 2.303 RT in kcal mol–1. The Arrhenius A-factor is higher than that obtained by competitive experiments, but in complete agreement with both collision theory and transition-state theory predictions. It is suggested that the Arrhenius parameters for the key reference reactions, [graphic ommitted] may need re-investigation.