The Cadmium Photosensitized Reactions of Propane

Abstract

An investigation has been made of the cadmium (5³P₁) photosensitized reactions of propane and of propane‐hydrogen mixtures at a temperature of 310°C. The main products are hydrogen and hexanes, together with smaller amounts of methane, butane, pentanes and heptanes. The quantum efficiency of propane decomposition is roughly 0.6. The results indicate that the primary reaction is a C–H bond split, $$\mathrm{Cd}{(}^3{P}_1\mathrm{)+}{\mathrm{C}}_3{\mathrm{H}}_8=\mathrm{CdH}+{\mathrm{C}}_3{\mathrm{H}}_7.$$ The main secondary reactions are $$\begin{array}{c}\mathrm{H}+{\mathrm{C}}_3{\mathrm{H}}_8={\mathrm{C}}_3{\mathrm{H}}_7+{\mathrm{H}}_2\\ 2{\mathrm{C}}_3{\mathrm{H}}_7={\mathrm{C}}_6{\mathrm{H}}_{14}.\end{array}$$ The liquid products of the reaction appear to be mainly 2,3‐di‐Me‐butane and/or 2‐Me‐pentane. This indicates that mainly secondary hydrogens are attacked, yielding the isopropyl radical. More C–C bond splitting occurs than is the case in the mercury photosensitized reaction at the same temperature. A possible explanation of this is that reactions are occurring which involve the CdH molecule.