Determining the Products and Mechanism of the C$_{2}$Cl$_{3}$+O$_{2}$ Reaction by Time-Resolved FTIR Emission Spectroscopy

The reaction products and mechanism of the C$_{2}$Cl$_{3}$ radical with O$_{2}$ have been studied by time-resolved FTIR emission spectroscopy. The chlorinated vinyl radical, C$_{2}$Cl$_{3}$, was generated by 248 nm photolysis of a C$_{2}$Cl$_{4}$ precursor. Vibrationally excited CO, CO$_{2}$ and ClCO products were observed. The time evolution of the emission intensity shows that CO$_{2}$ and ClCO are primary reaction products. In contrast, CO emission does not decay until \textit{ms} time scale indicating that CO products are due to secondary reactions, most likely, the further dissociation of ClCO. Two primary reaction channels are identified: C$_{2}$Cl$_{3}$ + O$_{2} \quad \diamondsuit $ CO$_{2}$ + CCl$_{3}$ $\diamondsuit $ ClCO + COCl$_{2}$ When reacting with O$_{2}$, the observed products and channels of the chlorinated vinyl radical, C$_{2}$Cl$_{3}$, turned out to be very similar to its counterpart, vinyl radical C$_{2}$H$_{3}$. Morokuma's DFT study$^{[1]}$ of the reaction C$_{2}$H$_{3}$+O$_{2}$ shows that the main reaction path proceeds through a three-membered CCO ring adduct. The question is, does C$_{2}$Cl$_{3}$ go through the same reaction path as C$_{2}$H$_{3}$? Does the substitution of H atom by heavier Cl atom make any difference in regard to the reaction mechanism? Further investigation combining \textit{ab initio }calculation is under way. \newline \newline [1] A.M.Mabel, E.W.G.Diau, M.C.Lin, and K.Morokuma, J.Am.Chem.Soc. 118, 9759 (1996)