The addition reaction of chlorine with ethylene (C2H 4) is expected to proceed via a free radical intermediate, the 2-chloroethyl radical, however, this intermediate has not been previously observed spectroscopically. Irradiation at 365 nm of a co-deposited mixture of Cl2, C2H4, and p-H2 at 3.2 K produces a series of new lines in the infrared spectrum. A strong line at 664.0 cm-1 and weaker lines at 562.1, 1069.9, 1228.0, 3041.1 and 3129.3 cm-1 are concluded to be due to a single carrier based on their behavior upon subsequent annealing to 4.5 K and secondary irradiation at 254 and 214 nm. The positions and intensities of these lines agree with the MP2/aug-cc-pVDZ predicted vibrational spectrum of the 2-chloroethyl (CH 2CH2Cl) radical. In order to confirm this assignment, isotopic experiments were performed with C2D4 and t-C 2H2D2 and the corresponding infrared bands due to the deuterium isotopomers of this radical (CD2CD2Cl and C2H2D2Cl) have been observed. A final set of experiments were performed following irradiation of the Cl2/C 2H4/p-H2 mixture at 365 nm, in which the matrix was irradiated with filtered infrared light from a globar source, which has been shown to induce reactions between isolated Cl atoms and matrix H 2 to produce HCl and H atoms. In these experiments, the major products observed were HCl, the ethyl radical (C2H5) and ethyl chloride (C2H5Cl) and the possible mechanisms for the formation of these species are discussed.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry