The Mercury Photosensitized Reactions of Propylene and Isoprene

Abstract

An investigation has been made of the reactions of propylene and isoprene with mercury (³P₁) atoms, at 30°C, in a static system. The reactions are similar in that the rates of consumption of both propylene and isoprene decrease with increasing pressure in the range of complete quenching. In addition, the quantum yields of both reactions are low. The products of the propylene reaction are liquid polymer and hydrogen, together with smaller amounts of methane, ethylene, and hexene. The principal steps in the mechanism proposed for the propylene reaction are ${\mathrm{C}}_3{\mathrm{H}}_6+\mathrm{Hg}{(}^3{P}_1\mathrm{)\to }{\mathrm{C}}_3{\mathrm{H}}_6^{*}+\mathrm{Hg}{(}^1{S}_0\mathrm{;\hspace{0.17em}}{\mathrm{C}}_3{\mathrm{H}}_6^{*}+{\mathrm{C}}_3{\mathrm{H}}_6\text{→2}{\mathrm{C}}_3{\mathrm{H}}_6\mathrm{;\hspace{0.17em}}{\mathrm{C}}_3{\mathrm{H}}_6^{*}\to {\mathrm{C}}_3{\mathrm{H}}_5+\mathrm{H}\mathrm{;\hspace{0.17em}}\mathrm{H}+{\mathrm{C}}_3{\mathrm{H}}_6\to {\mathrm{C}}_3{\mathrm{H}}_5+{\mathrm{H}}_2\mathrm{;\hspace{0.17em}}\mathrm{H}+{\mathrm{C}}_3{\mathrm{H}}_6\to {\mathrm{CH}}_3+{\mathrm{C}}_2{\mathrm{H}}_4$ ; followed by polymerization reactions of the type ${\mathrm{C}}_3{\mathrm{H}}_5+{\mathrm{C}}_3{\mathrm{H}}_6\to {\mathrm{C}}_6{\mathrm{H}}_{11}$ , etc.