ANALYSIS OF THE REACTION PATHS TO DISSOCIATION OF DICHLORO-ETHYLENES INTO CL-2 AND C2H2

The reaction paths to dissociation of dichloro-ethylenes (DCE) into Cl -2 and acetylene (C2H2) in the gas phase were studied, at the CCSD(T)/ 6-311G(d,p)//CASSCF(6,6)/6-31G(d) level of theory, including zero poin t energy correction. The structures and energies of reactants, transit ion states and products were determined through ab initio calculations . There are two principal paths to dissociation. One of them involves a number of transition states and intermediates where internal rotatio ns, H and Cl migrations are involved until the dissociation into Cl an d C2H2Cl radicals. The activation energy to this path is about 97 kcal /mol. On the other hand, C2H2Cl radicals were also predicted to be for med directly from cis- and trans-DCE. In addition, we have determined several paths to isomerization among the trans-, cis- and 1,1-dichloro -ethylene. We have concluded that these isomerization paths have activ ation energies below to the dissociation reaction. Therefore, the diss ociation process can proceed from every dichloro-ethylene. (C) 1998 El sevier Science B.V. All rights reserved.