Arrhenius Parameter Determination for the Reaction of Methyl Radicals with Iodine Species in Aqueous Solution

Abstract

The techniques of electron pulse radiolysis and direct ESR detection have been used to determine Arrhenius parameters for the recombination reaction of methyl radicals and methyl radical reaction with iodine in aqueous solution. At 22.8 °C, rate constants of 2k7 = (1.77 ± 0.16) × 109 dm3 mol-1 s-1 and k1 = (2.75 ± 0.43) × 109 dm3 mol-1 s-1, with corresponding activation energies of 14.89 ± 0.87 and 13.10 ± 0.71 kJ mol-1 (5.7−39.6 °C), were obtained respectively for these two reactions. The analogous reaction of methyl radicals with iodide or iodate was found to be much slower, with the room temperature rate constant for both reactions estimated as k < 106 dm3 mol-1 s-1.