Dynamics of endoergic substitution reactions. II. Br+{C2H2Cl2}→Cl+{C2H2ClBr}
摘要:
We have extended the crossed beams studies described in the preceding paper to the reactions of Br atoms with 1,1- and trans-dichloroethylene. The shapes of the product translational energy distributions and excitation functions for both reactions support our previous conclusion that Cl elimination from Br–R–Cl collision complexes can compete with Br elimination only in the limit that few vibrational modes of the complex are active in energy redistribution. The substitution cross section for the Br+CH2CCl2 reaction is considerably lower than that for the Br+trans-CHClCHCl reaction in the collision energy range 15–25 kcal/mol, suggesting that steric effects play a dominant role in determining the relative magnitudes of the cross sections.