Flash photolysis studies in a time-of-flight mass spectrometer. I. Divinyl ether and reactions of the vinyl and vinoxy radicals

The lower pressure flash photolysis of divinyl ether has been monitored by time‐of‐flight mass spectrometry. The primary photodecomposition process is restricted essentially to the formation of vinyl and vinoxy radials: ${\mathrm{C}}_2{\mathrm{H}}_3{\mathrm{OC}}_2{\mathrm{H}}_3\to {\mathrm{C}}_2{\mathrm{H}}_3+{\mathrm{C}}_2{\mathrm{H}}_3\mathrm{O}$ . The vinyl radical (m/e=27) has been observed directly and its 2nd order decay constant measured. The decay is primarily by disproportionation $2{\mathrm{C}}_2{\mathrm{H}}_3\to {\mathrm{C}}_2{\mathrm{H}}_4+{\mathrm{C}}_2{\mathrm{H}}_2$ and k₁₀ has an average value of ${\text{5.3± 0.5× 10}}^{\text{−12}}{\mathrm{cc\; molecule}}^{\text{−1}}·{\sec }^{\text{−1}}$ over the pressure range studied (65–200 mtorr). The vinoxy radical has not been observed directly in this work. Our results favor a rapid isomerization, followed by decomposition ${\mathrm{C}}_2{\mathrm{H}}_3\mathrm{O}\rightleftarrows {\mathrm{CH}}_3\mathrm{CO}\to {\mathrm{CH}}_3+\mathrm{CO}$ . A mass balance is achieved within 400 μsec of the photolysis flash and a mechanism proposed to account for the major (C₂H₄, C₂H₂, CO) and the minor products (CH₄, C₂H₆, 2‐butenal, acetaldehyde, and ketene).