Radiation Chemistry of Polycrystalline 1‐Chloropropane at 77 °K

The radiation chemistry of polycrystalline 1-chloropropane at 77°K has been studied, with special emphasis on the influence of the irradiation time. The most important dose effect is a very marked decrease of the yield of hexane as a function of the dose. The concentration of this product even passes through a maximum at high doses. A comparison is made with dose effects in glassy 1-chloropentane; the most important differences are additional positive dose effects on certain dichloropentanes and dichlorodecanes in 1-chloropentane. Two distinct processes appear to be responsible for dose effects in irradiated chloroalkanes at 77°K. The first is the reaction of mobile hydrogen atoms with neutral radicals, causing a decrease of the yield of these radicals in function of the dose. The second is charge transfer to radicals and olefins, which were formed in an earlier stage of the radiolysis. Both effects are present in glassy 1-chloropentane but only the first does manifest itself in polycrystalline 1-chloropropane. This may be due to a greater range of the secondary electrons or to better migration possibilities of chloride ions in glassy 1-chloropentane than in polycrystalline 1-chloropropane. In view of other experimental results, the last explanation seems to be the most plausible.