ELECTRON SCAVENGING IN RADIOLYSIS OF CYCLOHEXANE SOLUTIONS OF ALKYL HALIDES

The formation of alkyl radicals in irradiated solutions of CH3Cl, CH3Br, and C2H5Br in cyclohexane has been investigated at concentrations from 10-4 to 0.5 M. Experiments with added ethylene and cyclopropane show that the radicals do not result from reactions of either hydrogen atoms or positive ions. From this it appears that radical formation results exclusively from electron capture. The observed concentration dependence can be very well described by the expression (Chemical Equation Presented) The low concentration limit (Gfi) is identified with the free-ion yield and is found to be ∼ 0.1. It is believed that the high concentration limit (Gfi + Ggi), which is found to be 3.9 ± 0.1, can be identified with the total yield of electrons available for reaction with solutes. The above expression has been used to treat competitive electron capture by two alkyl halides. Deviations from ideality observed in the CH3Cl-C2H5Br system are interpreted in terms of electron transfer from a CH3Cl anion to the bromide. It is shown that such secondary ionic reactions can be described quantitatively.