Rate of Recombination of Radicals. III. Rate of Recombination of Ethyl Radicals

Abstract

The rate constants for the recombination (k₂) and the disproportionation (k₃) of ethyl radicals have been determined by applying the theory of the rotating sector to the photolysis of diethyl ketone. The values of k₂ are 1.5±1×10¹³, 2.0±0.5×10¹³, and 4.2±0.8×10¹³ cc mole^—1 sec^—1, at 50°C, 100°C, and 150°C, respectively. The ratio k₃/k₂ is taken to be 0.12 from other work. An Arrhenius plot of these results indicate an energy of activation for k₂ of 2.0±1 kcal/mole. These results are shown to be in agreement with existing theories. A simplified transition state theory calculation of k₂ is offered, based on the change in the number of degrees of freedom from radicals to activated complex.