Temperature (290-400Â K) and pressure (5-900Â Torr) dependence of the kinetics of the reactions of chlorine atoms with propene and 1-butene

►Kinetics of Cl + propene or butene reactions studied by relative rate method. ►Temperature dependence (298-370 K near 1 bar) is small (Ea ≈ −0.3 kcal mole−1). ►Results contradict earlier experiments which showed an unexpectedly large negative activation energy (Ea = −4.5 kcal mole−1).