The recombination of CCl3 radicals with CH2X (X = H, CH3, and CF3) radicals was used to generate CH3CCl3, CH3CH2CCl3, and CF3CH2CCl3 molecules with approximately 90 kcal mol-1 of vibrational energy in a room temperature bath gas. The competition between collisional deactivation and unimolecular reaction was used to obtain the experimental rate constants for 1,2-HCl elimination of 8 x 109 s-1, 1.5 x 108 s-1, and 7 x 106 s-1 for X = H, CH3 and CF3, respectively. These experimental rate constants were matched to calculated statistical unimolecular rate constants to assign threshold energies to the three HCl elimination reactions to determine the effect of electron-donating and electron-withdrawing substituents. The models for the transition states for the calculations were obtained from molecular structure calculations using Density Functional Theory.  Substituent effects to be discussed include the impact of the addition of Cl-atoms to the same carbon and the effect of electron-donating and withdrawing substituents on the carbon losing the hydrogen.

Unimolecular rate constant for 1,2-HCl elimination from CF3CH2CCl3, CH3CH2CCl3, and CH3CCl3: The threshold energy, E0, for 1,1,1-trichloroethane and the effect of electron-withdrawing and electron�donating on E0

247th National Meeting (2014)

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