Mutual reaction of isopropyl radicals

Abstract

The second order mutual reaction between isopropyl radicals has been studied over the temperature range 301–424 K. Kinetic measurements of the overall termination rate, using a molecular modulation spectrometer, have been combined with product analysis studies to determine Arrhenius parameters for the recombination (k_r) and disproportionation reactions. The values obtained: k_r= 1.4 × 10^–11[exp(–1340 J mol^–1//_RT)] cm³ molecule^–1 s^–1, k_d= 5.0 × 10^–12[exp(210 J mol^–1//_RT)] cm³ molecule^–1 s^–1, give good agreement with product analysis studies over a wide range of temperatures. These rate coefficients are correct to ± 20% over the stated temperature range, and the error in the activation energies is ± 2600 J mol^–1(95% confidence limits). The parameters for k_r extrapolate to a value that is about twice the value measured by the very low pressure pyrolysis method at 750 K.