Primary steps in the photolysis of cis ‐1,2‐dichloroethylene

The photolysis of cis ‐1,2‐dichloroethylene has been investigated in the presence of I 2 as a function of incident wavelength and as a function of initial cis pressure. The results indicate that at ± > 2200Å the following primary processes occur:\documentclass{article}\pagestyle{empty}\begin{document}$$ cis{\rm - 1,}2{\rm - C}_{\rm 2} {\rm H}_{\rm 2} {\rm Cl}_{\rm 2}^ * \to {\rm C}_{\rm 2} {\rm H}_{\rm 2} + {\rm Cl}_{\rm 2} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ cis{\rm - 1,2 - C}_{\rm 2} {\rm H}_{\rm 2} {\rm Cl}_{\rm 2}^ * \to {\rm C}_{\rm 2} {\rm HCl} + {\rm HCl} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ cis{\rm - 1,}2{\rm - C}_{\rm 2} {\rm H}_{\rm 2} {\rm Cl}_{\rm 2}^ * \to {\rm C}_{\rm 2} {\rm H}_{\rm 2} {\rm Cl} + {\rm Cl} $$\end{document}The lifetime of the excited state yielding the above products is estimated at about 2.4×10 −9 sec. At shorter wavelengths additional C 2 H 2 is produced by decomposition of a vibrationally excited C 2 H 2 Cl radical. Scavenging of the CHClCH radical by I 2 produced trans and cis ‐CHClCHl in a ratio of 4 to 1, respectively.